TY - JOUR TI - Air pollution at college football games: Developing a methodology for measuring air pollutant exposure in a sport event microenvironment AU - Bunds, K.S. AU - Casper, J.M. AU - Frey, H.C. AU - Barrett, M. T2 - Event Management AB - International organizations such as the United Nations have begun to recognize the connection between sport events and air pollution. However, to date, there has been a dearth of research attempting to measure air pollution at sporting events. To address the lack of research on air pollution at sporting events, in this article we developed a methodology for measuring the air pollution at a college football game utilizing both stationary and mobile monitoring systems. Stationary monitors allowed for the creation of a microenvironment wherein we could examine the overall particulate matter exposure within the stadium and tailgate lot areas. Mobile monitors allowed for the examination of specific causes of spikes in air pollution. We found grills, generators, and cars caused pollutant spikes, which were, at times, over 20 times worse than the recognized levels for moderate air quality. Additionally, while the overall pollution in the microenvironment was elevated, pollutant levels during postgame (i. e., where there is a rush of individuals leaving at the same time) were consistently and considerably higher. Implications for practice and future research include event policy considerations and the application of the methodology across alternative sporting venues/contexts. DA - 2019/// PY - 2019/// DO - 10.3727/152599518X15403853721484 VL - 23 IS - 3 SP - 399-412 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073696760&partnerID=MN8TOARS ER - TY - RPRT TI - Evaluating Policy and Market Barriers for Forest Biomass Energy Development. Report prepared for the Office of the Chief Economist, United States Department of Agriculture AU - Benedum, M.E. AU - Galik, C.S. AU - Kauffman, M. AU - Becker, D.R. A3 - United States Department of Agriculture DA - 2019/// PY - 2019/// PB - United States Department of Agriculture ER - TY - JOUR TI - Reduction Kinetics of Perovskite Oxides for Selective Hydrogen Combustion in the Context of Olefin Production AU - Dudek, Ryan B. AU - Tian, Yuan AU - Jin, Gaochen AU - Blivin, Millicent AU - Li, Fanxing T2 - ENERGY TECHNOLOGY AB - Chemical looping represents a novel approach for generating light olefins in which thermal cracking or catalytic dehydrogenation is coupled with selective hydrogen combustion (SHC) by a metal oxide redox catalyst, which enables autothermal operation, increased per‐pass conversion, and greater‐than‐equilibrium yields. Recent studies indicate that Na 2 WO 4 ‐promoted perovskite oxides are effective redox catalysts with high olefin selectivity. Herein, kinetic parameters, rates, and reaction models for the reduction of unpromoted and Na 2 WO 4 ‐promoted CaMnO 3 redox catalysts by H 2 , C 2 H 4 , and C 2 H 6 , is reported. Reduction rates of CaMnO 3 under ethylene and ethane are significantly lower than under H 2 . Model fitting of reduction kinetics show good agreement with reaction order–controlled models for CaMnO 3 reduction and predict greater oxygen site dependence and higher activation energy for CaMnO 3 reduction by C 2 H 4 as compared with H 2 . Avrami–Erofe'ev nucleation and growth models provide the best fit to the reduction of Na 2 WO 4 /CaMnO 3 in H 2 and in C 2 H 4 . After Na 2 WO 4 promotion, the reduction rate of CaMnO 3 is three orders of magnitude lower in ethylene in comparison to hydrogen, consistent with its superior selectivity to hydrogen combustion. The models developed can be applied toward reactor design and optimization in the context of enhanced olefin production via SHC under a cyclic redox scheme. DA - 2019/// PY - 2019/// DO - 10.1002/ente.201900738 VL - 8 IS - 8 SP - 1900738 KW - combustion KW - cracking KW - dehydrogenation KW - kinetics KW - olefin KW - perovskites KW - reduction ER - TY - JOUR TI - A- and B-site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation AU - Dou, Jian AU - Krzystowczyk, Emily AU - Wang, Xijun AU - Robbins, Thomas AU - Ma, Liang AU - Liu, Xingbo AU - Li, Fanxing T2 - CHEMSUSCHEM AB - Chemical-looping air separation has numerous potential benefits in terms of energy saving and emission reductions. The current study details a combination of density functional theory calculation and experimental efforts to design A- and B-site codoped SrFeO3 perovskites as "low-temperature" oxygen sorbents for chemical-looping air separation. Substitution of the SrFeO3 host structure with Ca and Co lowers oxygen vacancy formation energy by 0.24-0.46 eV and decreases the oxygen release temperature. As a result, Sr1-x Cax Fe1-y Coy O3 (SCFC; x=0.2, 0.040 min) without signs of coke formation. When used as supports for NiO, the resulting oxygen carriers showed no sign of carbon deposition under typical methane CLC environments. In comparison, NiO supported on inert MgAl2O4 exhibited significant coke formation after only 2.5 min. Moreover, NiO supported on NiFe2O4 and BaFe2O4 exhibited faster redox activity and higher oxygen carrying capacity when compared to the inert MgAl2O4-supported NiO. Detailed investigation of the reduction behavior of NiFe2O4-supported NiO revealed extensive solid-state reactions and Ni/Fe exchanges among the support, NiO, and newly formed phases. Specifically, initial weight loss in NiFe2O4-supported NiO was associated with reduction of the oxygen carrier to metallic Ni and Fe3O4 phases. Subsequent coke inhibition was attributed to the slow reduction of Fe3O4 and FeO phases. Multi-cyclic redox studies indicated that NiFe2O4-supported NiO gradually lost its redox activity. In comparison, both MgFe2O4- and BaFe2O4-supported NiO exhibited satisfactory redox stability, activity, and coke resistance. DA - 2019/// PY - 2019/// DO - 10.1016/j.cattod.2019.09.010 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85072723300&partnerID=MN8TOARS ER - TY - JOUR TI - Variational Assimilation of Streamflow Observations in Improving Monthly Streamflow Forecasting AU - Mazrooei, A. AU - Sankarasubramanian, A. AU - Wood, A.W. T2 - Hydrology and Earth System Sciences AB - Abstract. Uncertainties associated with the initial conditions (e.g. soil moisture content) of a hydrologic model have been recognized as one of the main sources of errors in hydrologic predictions, specifically over a rainfall-runoff regime. Apart from the recent advances in Data Assimilation (DA) for improving hydrologic predictions, this study explores variational assimilation (VAR) of gauge-measured daily streamflow data for updating initial state of soil moisture content of Variable Infiltration Capacity (VIC) Land Surface Model (LSM) in order to improve streamflow simulations as well as monthly streamflow forecasting. The study is conducted for the Tar River basin in North Carolina over 20-year period (1991–2010). The role of two critical parameters of VAR DA – the frequency of DA application and the length of assimilation window – in determining the skill of DA-improved streamflow predictions is also assessed. We found that correcting VIC model's initial conditions using a 7-day assimilation window results in the highest improvement in the skill of streamflow predictions quantified by Kling-Gupta Efficiency (KGE) and Nash-Sutcliffe Efficiency (NSE) metrics. In addition, the potential gain from VAR DA framework is quantified and compared under two 1-month ahead streamflow forecasting schemes: 1) deterministic forecasts developed by using ECHAM4.5 GCM 1-month ahead precipitation forecasts and 2) Probabilistic forecasts from Ensemble Streamflow Prediction (ESP) approach. This study also examines the persistence of the DA impact in the monthly predictions by quantifying the enhanced accuracy in daily flows over extending forecast lead time blocks. Analyses show that the the corrected initial state conditions continually enhance the 7–8 days ahead predictions, but after that the errors in forcings dominate the DA effects. Still, the overall impact of VAR DA in monthly streamflow forecasting is positive. DA - 2019/// PY - 2019/// DO - 10.5194/hess-2019-288 M3 - preprint ER - TY - CONF TI - Bi–Directional Solid-State Circuit Breaker for MV Applications Based on SuperCascode Switching AU - Ballard, Bahji AU - Mehrotra, Utkarsh AU - Hopkins, Douglas C. T2 - Power America Annual Meeting C2 - 2019/2/12/ CY - Raleigh, NC DA - 2019/2/12/ PY - 2019/2/12/ ER - TY - CONF TI - Trends in Power Electronics Packaging AU - Hopkins, Douglas C. T2 - FREEDM Systems Center Annual Research Symposium C2 - 2019/4/10/ CY - Raleigh, NC DA - 2019/4/10/ PY - 2019/4/10/ ER - TY - CONF TI - New Dynamic Power MOSFET Model to Determine Maximum Device Operating Frequency AU - Morgan, Adam AU - Kanale, Ajit AU - Han, Kijeong AU - Baliga, Jayant AU - Hopkins, Douglas C. T2 - FREEDM Systems Center Annual Research Symposium C2 - 2019/4/10/ CY - Raleigh, NC DA - 2019/4/10/ PY - 2019/4/10/ ER - TY - CONF TI - High Frequency Self-Oscillating WBG-based Power Conversion AU - Morgan, Adam AU - Gao, Bo AU - Hopkins, Douglas C. T2 - FREEDM Systems Center Annual Research Symposium C2 - 2019/4/10/ CY - Raleigh, NC DA - 2019/4/10/ PY - 2019/4/10/ ER - TY - CONF TI - ERCD Power Stage Characterization for MV SSCB Application AU - Sinha, Sourish S. AU - Ballard, Bahji AU - Hopkins, Douglas C. T2 - Power America Summer Workshop C2 - 2019/8/6/ CY - Raleigh, NC DA - 2019/8/6/ PY - 2019/8/6/ ER - TY - CONF TI - Development of a High Frequency LLC Resonant Converter for Investigation of MLCCs for EV applications AU - Guven, Musab AU - Gao, Bo AU - Hopkins, Douglas C. T2 - Power America Summer Workshop C2 - 2019/8/6/ CY - Raleigh, NC DA - 2019/8/6/ PY - 2019/8/6/ ER - TY - CONF TI - WBG Solid State Circuit Protection using 10kV/200 A Super Cascode power module AU - Mehrotra, Utkarsh AU - Hopkins, Douglas T2 - Power America Summer Workshop 2019 C2 - 2019/8/6/ CY - Raleigh, NC DA - 2019/8/6/ PY - 2019/8/6/ ER - TY - CONF TI - Opportunities in Power Applications using Epoxy Resin Composite Dielectrics AU - Hopkins, Douglas AU - Ballard, Bahji T2 - Power America Summer Workshop 2019 C2 - 2019/8/6/ CY - Raleigh, NC DA - 2019/8/6/ PY - 2019/8/6/ ER - TY - CONF TI - Advances in Organic Substrate Approaches for High Voltage Power Electronics Packaging AU - Cheng, Tzu-Hsuan AU - Gao, Bo AU - Boteler, Lauren AU - Hopkins, Douglas T2 - PCB Carolina C2 - 2019/11/13/ CY - Raleigh, NC DA - 2019/11/13/ PY - 2019/11/13/ ER - TY - CONF TI - Power Packaging Assembly Challenges AU - Hopkins, Douglas C. T2 - A.R.E.A. Consortium Meeting Universal Instruments C2 - 2019/3/27/ CY - Binghamton, NY DA - 2019/3/27/ PY - 2019/3/27/ ER - TY - CONF TI - 1.2 kV, 10 A, 4H-SiC Bi-Directional Field Effect Transistor (BiDFET) with Low On-State Voltage Drop AU - Kanale, Ajit AU - Cheng, Tzu-Hsuan AU - Hanl, Kijeong AU - Baliga, B. Jayant AU - Bhattacharya, Subhashish AU - Hopkins, Douglas T2 - International Conference on Silicon Carbide and Related Materials C2 - 2019/9/29/ CY - Kyoto, Japan DA - 2019/9/29/ PY - 2019/9/29/ ER - TY - CONF TI - Characterization of a Topside Cooled Epoxy-Resin Composite Dielectric (ERCD) Package for Bi-Directional Power Switch AU - Cheng, Tzu-Hsuan AU - Gao, Bo AU - Nishiguchi, Kenji AU - Hopkins, Douglas T2 - ASME International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems (InterPACK) C2 - 2019/10/7/ CY - Anaheim, CA DA - 2019/10/7/ PY - 2019/10/7/ ER - TY - CONF TI - Advances in Organic Substrate Approaches for High Voltage Power Electronics Packaging AU - Hopkins, Douglas C. AU - Cheng, Tzu-Hsuan AU - Gao, Bo AU - Boteler, Lauren T2 - ASME International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems (InterPACK) C2 - 2019/10/7/ CY - Anaheim, CA DA - 2019/10/7/ PY - 2019/10/7/ ER - TY - CONF TI - Designing for Switching Stresses in a Circuit Breaker Application using SiC Semiconductors AU - Ballard, Bahji AU - Mehrotra, Utkarsh AU - Hopkins, Douglas C. T2 - 7th IEEE Workshop on Wide Bandgap Power Devices and Applications (WiPDA C2 - 2019/10/29/ CY - Raleigh, NC DA - 2019/10/29/ PY - 2019/10/29/ ER - TY - CONF TI - Design and Integration of WBG Solid State Circuit Protection AU - Hopkins, Douglas C. AU - Ballard, Bahji AU - Mehrotra, Utkarsh T2 - IEEE Applied Power Electronics Conference C2 - 2019/3/17/ CY - Anaheim, CA DA - 2019/3/17/ PY - 2019/3/17/ ER - TY - RPRT TI - Edge Interconnect Packaging of Integrated Circuits for Power Systems AU - Kulick, Jason M. AU - Hopkins, Douglas DA - 2019/6/18/ PY - 2019/6/18/ M1 - 10,325,875B2 M3 - US Patent SN - 10,325,875B2 ER - TY - CONF TI - Thermal Characteristics and Simulation of an Integrated GaN eHEMT Power Module AU - Jorgensen, Asger Bjorn AU - Cheng, Tzu-Hsuan AU - Hopkins, Douglas AU - Beczkowski, Szymon AU - Uhrenfeldt, Christian AU - Munk-Nielsen, Stig T2 - 2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe) AB - Compact power modules are emerging which combine both direct bonded copper (DBC) and printed circuit boards (PCB) in integrated structures to achieve fast switching of wide bandgap semiconductors. The literature presenting the new integrated structures only include the DBC in their thermal analysis, and thus the influence of the PCB is often disregarded. In this paper the thermal characteristics of a new integrated GaN eHEMT power module are obtained experimentally. A simulation workflow to extract the thermal characteristics of the integrated module structure using finite element method software is presented and verified. The results predict an error of up to 13% in thermal impedance if the PCB board is not included in the simulation model. C2 - 2019/9// C3 - 2019 21st European Conference on Power Electronics and Applications (EPE '19 ECCE Europe) DA - 2019/9// DO - 10.23919/epe.2019.8915012 PB - IEEE SN - 9789075815313 UR - http://dx.doi.org/10.23919/epe.2019.8915012 DB - Crossref ER - TY - CONF TI - A High-Bandwidth Resistive Current Sensing Technology for Breakers and Desaturation Protection AU - Gao, Bo AU - Mehrotra, Utkarsh AU - Hopkins, Douglas C. T2 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) AB - High switching frequencies, steeper voltage and current slopes make for challenging requirements for real time current sensing, especially due to overshoot from sensing element inductance. High-bandwidth current sensing is required to ensure safe, reliable and efficient operations and to engage protection during critical failures. This paper describes and demonstrates a high bandwidth resistive current sensing technology for solid state circuit protection and diode-less power device desaturation protection. The sensor uses mutual inductance cancellation as well as residual inductive voltage subtraction for ultra-low-overshoot transient response. Full design steps and equations are presented for scaling the design. The demonstration design is fabricated using rigid and flexible PCB technologies. Test results show a 70.5% reduction of insertion inductance for the same power dissipation and sensitivity. VNA and spectrum analyzer measurements are used to characterize the prototypes of the proposed design. The paper also discusses two applications of desaturation protection and overcurrent protection for SiC FETs. C2 - 2019/10// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) DA - 2019/10// DO - 10.1109/wipda46397.2019.8998767 PB - IEEE SN - 9781728137612 UR - http://dx.doi.org/10.1109/wipda46397.2019.8998767 DB - Crossref ER - TY - RPRT TI - Flexible Large Power Solid State Transformer (FLP-SST) AU - Bhattacharya, Subhasish A3 - Office of Scientific and Technical Information (OSTI) AB - A large power transformer (LPT) is a major component in the electric power system grid. With the passage of time their reliability in terms of failure and service maintenance has been a big concern. According to a report by EPRI, various agencies have emphasized, and recent events have demonstrated, the critical nature of power transformers in the face of possible high-impact, low-frequency (HILF) events. The HILF events include intentional malicious events (e.g., physical attacks, cyber-attacks, coordinated attacks, electromagnetic pulse weapons, and others), natural disasters (e.g., hurricanes, earthquakes, severe geomagnetic disturbances, etc.), and non-intentional or accidental events such as nuclear power plant accidents. With aging, the line frequency transformers (LFTs) are also prone to failure due to insulation degradation, coolant leakage, mechanical failure, inadequate maintenance, etc. and thus poses a bigger threat to the electrical grid. Moreover, these transformers are custom made to fit the needs at the substation and weighs approximately between 100-400 tons, hence are neither interchangeable nor stored as a spare one. Hence reasonable efforts need to be made regarding the replacement of the LPT with a more feasible technology that does not pose similar issues. The concept of Flexible Large Power Solid-State Transformer (FLPSST) has addressed the aforementioned issues to provide an economical solutions for the failure of LPTs. DA - 2019/2/25/ PY - 2019/2/25/ DO - 10.2172/1647580 PB - Office of Scientific and Technical Information (OSTI) UR - https://doi.org/10.2172/1647580 ER - TY - CONF TI - New Dynamic Power MOSFET Model to Determine Maximum Device Operating Frequency AU - Morgan, Adam J. AU - Kanale, Ajit AU - Han, Kijeong AU - Baliga, Jayant AU - Hopkins, Douglas C. T2 - 2019 IEEE Applied Power Electronics Conference and Exposition (APEC) AB - Improved SiC-MOSFETs with high HF-FOMs are enabling unprecedented high frequency MHz-switching. However, other SiC-MOSFET parameters, such as capacitance and total gate resistance dictate the theoretical limit on the maximum switching frequency, and are often not considered. These latter parameters directly influence the real-time dynamic on-resistance when the propagation-time of gate voltage approaches that of the switching time period. To properly characterize MHz-switching performance, minimum switching times are calculated using a modified input RC time constant analysis that incorporates a time-dependent active area. An empirical comparison is conducted for several SiC-MOSFETs. A novel, equivalent RC ladder and resistor switch network model is proposed to describe the propagation of gate voltage and dynamic activation of unit-cells composing the SiC-MOSFET channel. A time-dependent effective on-resistance, accounting for transition and steady state conduction on-times, is determined and verified in both simulation and experiment. New high-frequency performance metrics for SiC-MOSFETs are proposed to provide greater insight for design engineers, and provide maximum expected operating limits. This will also help guide semiconductor designers to better match device to application. C2 - 2019/3// C3 - 2019 IEEE Applied Power Electronics Conference and Exposition (APEC) DA - 2019/3// DO - 10.1109/APEC.2019.8722197 PB - IEEE SN - 9781538683309 UR - http://dx.doi.org/10.1109/APEC.2019.8722197 DB - Crossref ER - TY - CONF TI - A Geo-processing Tool for co-locating the dependency of critical infrastructure with hydrologic information network AU - Mukhopadhyay, S. AU - Mazrooei, A. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - The Roles of Climate Variability on Runoff at Daily, Monthly, Inter-annual, and Mean Annual Scales AU - Yao, L. AU - Libera, D. AU - Kheimi, M. AU - Arumugam, S. AU - Wang, D. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - What defines a flood? Building shared understanding across differing attributes and definitions of flooding AU - Archfield, S.A. AU - Ryberg, K.R. AU - Blum, A.G. AU - Barth, N.A. AU - Awasthi, C. AU - Li, H. AU - Abeshu, G.W. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Climate-Water-Energy Nexus: An Integrated Modeling Framework to Analyze Water and Power Systems Under a Changing Climate AU - Ford, L. AU - Queiroz, A. AU - DeCarolis, J. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - The role of climate on crop yield per unit area across the contiguous United States AU - Kumar, H. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Using an Integrated Groundwater and Surface Water Model for Understanding the Effects of Climate Change Scenarios on the Food-Energy-Water Nexus AU - Libera, D. AU - Wang, D. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - How Regional Evapotranspiration Fluxes are altered due to Urbanization? AU - Mazrooei, A. AU - Arumugam, S. AU - Wang, D. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - How does flow alteration propagate across a large, highly-regulated basin? Dam attributes, network context, and implications for biodiversity AU - Ruhi, A. AU - Hwang, J. AU - Devineni, N. AU - Mukhopadhyay, S. AU - Kumar, H. AU - Comte, L. AU - Worland, S. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Sustainable Water Management in the Lower Colorado Basin: Influence of Climate and Regulatory Context on the Ability to Meet Human and Environmental Water Needs AU - Tu, T. AU - Arumugam, S. AU - Dong, X. AU - Dyckman, C. AU - Grantham, T. AU - Olson, L.J. AU - Ruddell, B. L. AU - Ulibarri, N. AU - Ruhi, A. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Human and climate variables explain spatio-temporal patterns of streamflow variation across the United States AU - Chalise, D. AU - Arumugam, S. AU - Ruhi, A. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Sustainable Urban Systems: Managing the Urban Multiplex and its Hydrologic Challenges AU - Yeghiazarian, L. AU - Merwede, V. AU - Golden, H.E. AU - Arumugam, S. AU - Welty, C. AU - Bales, J. AU - Cai, X. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Revising Flood-Frequency Curves under Climate Change in the United States AU - Awasthi, C. AU - Archfield, S.A. AU - Kiang, J.E. AU - Ryberg, K.R. AU - Arumugam, S. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - The Utility of Gauge-measured Streamflow Records in Improving Month-ahead Streamflow Forecasts through Variational Data Assimilation AU - Mazrooei, A. AU - Arumugam, S. AU - Wood, A. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - CONF TI - Understanding Drivers of Subseasonal to Seasonal Streamflow Variability over Contiguous United States AU - Mukhopadhyay, S. AU - Wood, A. AU - Arumugam, S. AU - Rajagopalan, B. T2 - American Geophysical Union Fall Meeting C2 - 2019/// CY - San Francisco, CA DA - 2019/// PY - 2019/12/9/ ER - TY - SOUND TI - Challenges in Understanding Continental Scale Groundwater Variability, Change and Appropriation AU - Arumugam, S. DA - 2019/// PY - 2019/// ER - TY - JOUR TI - Improving monthly streamflow forecasts through assimilation of observed streamflow for rainfall-dominated basins across the CONUS AU - Mazrooei, Amirhossein AU - Sankarasubramanian, A. T2 - Journal of Hydrology AB - Among different sources of uncertainty in hydrologic modeling (i.e., model structure, parameter estimation, input data, etc.), consecutive error reduction of model initial conditions can prevent a model from drifting away from reality and consequently improving model estimates. Most approaches that evaluated the correction of initial conditions through data assimilation (DA) have focused on improving hydrologic model simulations (i.e., under observed forcings) rather than evaluating the model performance in a forecasting context. This paper investigates the utility of Ensemble Kalman Filter (EnKF) data assimilation in which available observed streamflow is exploited to update state variables of a conceptual water balance model for forecasting monthly streamflow over 340 rainfall-dominated river basins across the contiguous United States (CONUS). Our results demonstrate that after EnKF application, streamflow simulation skill improves in terms of both Relative Root Mean Square Error (R-RMSE) and correlation coefficient (CC) for almost 90% of the selected river basins. Evaluating the model performance under different flow conditions shows that EnKF has stronger positive effect on monthly low flow predictions comparing to monthly high flows particularly during the summer season. The utility of EnKF is also assessed in the context of 1-month ahead streamflow forecasting. Due to the updated model initial conditions, streamflow forecasts are improved throughout the year even though the skill in hydrologic forecasts is predominantly dependent on the accuracy of precipitation forecasts. DA - 2019/8// PY - 2019/8// DO - 10.1016/j.jhydrol.2019.05.071 VL - 575 SP - 704-715 J2 - Journal of Hydrology LA - en OP - SN - 0022-1694 UR - http://dx.doi.org/10.1016/j.jhydrol.2019.05.071 DB - Crossref KW - Streamflow forecasting KW - Hydrologic data assimilation KW - Conceptual water balance model ER - TY - JOUR TI - Modular‐scale ethane to liquids via chemical looping oxidative dehydrogenation: Redox catalyst performance and process analysis AU - Neal, Luke AU - Haribal, Vasudev AU - McCaig, Joseph AU - Lamb, H. Henry AU - Li, Fanxing T2 - Journal of Advanced Manufacturing and Processing AB - Abstract The difficulties in the liquefaction and transportation of ethane in shale gas has led to significant rejection, via reinjection or flaring, of this valuable hydrocarbon resource. Upgrading this low‐value, isolated ethane into easily transportable liquid fuels is a promising solution to this supply glut. In this study, we present a modular system that can potentially be operated economically at geographically isolated gas‐processing facilities. The modular ethane‐to‐liquids (M‐ETL) system uses a chemical looping‐oxidative dehydrogenation (CL‐ODH) technology to efficiently convert ethane and natural gas liquids into olefins (primarily ethylene) via cyclic redox reactions of highly effective redox catalyst particles. The resulting olefins are then converted to gasoline and mid‐distillate products via oligomerization. CL‐ODH eliminates air separation and equilibrium limitations for olefin generation. It also simplifies the process scheme and reduces energy consumption. Here, we present experimental proof‐of‐concept data on CL‐ODH conversion of ethane to ethylene. Using the CL‐ODH performance data at 750°C, we show that a simple, single‐pass configuration can be economically viable at distributed sites. We identify that economic factors such as the capital cost, price of ethane feed, and value of electricity byproduct have strong effects on the required selling price of the liquids. It is also noted that the economic viability of the M‐ETL system is relatively insensitive to the liquid yield under a low ethane price scenario. The demand and value of electricity at distributed locations, on the other hand, can play an important role in the optimal process configuration and economics. DA - 2019/4// PY - 2019/4// DO - 10.1002/AMP2.10015 VL - 1 IS - 1-2 SP - e10015 J2 - J Adv Manuf Process LA - en OP - SN - 2637-403X 2637-403X UR - http://dx.doi.org/10.1002/AMP2.10015 DB - Crossref ER - TY - CHAP TI - Payments for Ecosystem Services AU - James, N. AU - Sills, E. T2 - Oxford Research Encyclopedia of Environmental Science A2 - Sherman, Herman H. AB - Payments for ecosystem or environmental services (PES) are broadly defined as payments (in kind or in cash) to participants (often landowners) who volunteer to provide the services either to a specific user or to society at large. Payments are typically conditional on agreed rules of natural resource management rather than on delivery of the services. The rules range from protection of native ecosystems to installation of conservation practices. The earliest proponents of PES were economists who argued that they are a cost-effective way to conserve forests, manage watersheds, and protect biodiversity. Political support for PES rests on the claim that these programs can alleviate poverty among participants as well as protect the environment. More recent literature and experience with PES reveals barriers to achieving cost-effectiveness and poverty alleviation, including many related to the distribution of participation. The Costa Rican experience illustrates the choices that must be made and the potential for innovation in the design of PES programs. PY - 2019/// DO - 10.1093/acrefore/9780199389414.013.580 PB - Oxford University Press ER - TY - CHAP TI - SDG 1: No Poverty – Impacts of Social Protection, Tenure Security and Building Resilience on Forests AU - Lawlor, K. AU - Sills, E. AU - Atmadja, S. AU - Lin, L. AU - Songawathan, K. T2 - Sustainable Development Goals: Their Impacts on Forests and People A2 - Katila, Pia A2 - Colfer, Carol J. Pierce A2 - De Jong, Wil A2 - Galloway, Glenn A2 - Pacheco, Pablo A2 - Winkel, Georg PY - 2019/// SP - 17-47 PB - Cambridge University Press ER - TY - JOUR TI - Prediction of hourly solar radiation using temperature and humidity for real-time building energy simulation AU - Gaballa, Hany AU - Cho, Soolyeon T2 - CLIMATE RESILIENT CITIES - ENERGY EFFICIENCY & RENEWABLES IN THE DIGITAL ERA (CISBAT 2019) AB - Abstract Solar radiation is considered one of the most substantial energy sources in our life. This paper discusses how to develop an algorithm to predict real-time hourly solar radiation based on readily available weather data such as temperature and humidity. Artificial Neural Network is one of the most effective technologies for developing algorithms to predict solar radiations. Hidden nodes, learning rates, and epochs are the main three variables. An optimization method is proposed to provide the optimum value of the variables depending on the Coefficient of Variance of the Root Mean Square Error, Normalized Mean Bias Error, and Coefficient of determination. DA - 2019/// PY - 2019/// DO - 10.1088/1742-6596/1343/1/012049 VL - 1343 SP - SN - 1742-6596 ER - TY - CONF TI - Voltage Balancing of Series Connected Clamping Diodes in Medium Voltage NPC Converter enabled by Gen-3 10 kV SiC MOSFETs for Asynchronous Micro-Grid Power Conditioning System (AMPCS) AU - Jakka, V.N. AU - Kumar, A. AU - Parashar, S. AU - Rastogi, S.K. AU - Kolli, N. AU - Jaiswal, R. AU - Bhattacharya, S. AB - Asynchronous micro-grid power conditioning system (AMPCS) had been proposed for integrating two medium voltage nonsynchronous grids. Neutral point clamped (NPC) converter based active front-end converters (AFECs) and three-phase dual active bridge (DAB) are used as basic building blocks for the AMPCS. Switching and voltage clamping operations of these NPCs are achieved using series connected 10 kV SiC MOSFETs and 10 kV SiC JBS diodes, respectively. In the earlier reported work on AMPCS, voltage balancing across the series connected MOSFETs is reported. It is observed that in a few cases voltage unbalance also appears across the series connected clamping diodes due to dissimilar nature of their characteristics. This voltage imbalance across the clamping diodes can affect the operation of AMPCS. In this digest, a balancing scheme for series connected clamping diodes of the AMPCS system using passive snubber circuit is presented. A systematic set of experiments have been reported which can be conducted to ensure the voltage balancing across the series connected clamping diodes before applying them in actual medium voltage AMPCS. The balancing scheme is validated using the experimental results. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8911830 SP - 5798-5804 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076718597&partnerID=MN8TOARS ER - TY - CONF TI - Supplying medium voltage to data-center racks directly using SiC-based converter AU - Samanta, S. AU - Wong, I. AU - Beddingfield, R. AU - Bhattacharya, S. AU - Zhu, G. AU - Pahl, B. AB - With the increase in size of data centers and cloud computing, its power demand is also rising sharply. Traditionally, this power distribution is achieved at about 400VDC which is inconvenient because it requires very bulky conductor to prevent high copper loss. In this paper, a new power distribution architecture for data centers is reported where direct medium voltage distribution to data-center racks are achieved with SiC based inverter. The safety issues raised due to bringing medium voltage to the racks are addressed with contactless power transfer technology. The rectifier circuit handles a high current at 48V, and synchronous rectification would be suitable to boost the efficiency. In this paper, a GaN based synchronous rectification is studied. This proposed converter circuit is analyzed and simulated in PowerSim 11. A 3kW experimental setup is developed in the lab to verify the analysis and simulation performances of the converter, where the input is 1000V and the output is 48V. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998837 SP - 85-92 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081182419&partnerID=MN8TOARS ER - TY - BOOK TI - Superior short circuit performance of 1.2KV SIC JBSFETs compared to 1.2KV SIC mosfets AU - Kanale, A. AU - Han, K. AU - Baliga, B.J. AU - Bhattacharya, S. AB - The high-temperature switching performance of a 1.2kV SiC JBSFET is compared with a 1.2kV SiC MOSFET using a clamped inductive load switching circuit representing typical H-bridge inverters. The switching losses of the SiC MOSFET are also evaluated with a SiC JBS Diode connected antiparallel to it. Measurements are made with different high-side and low-side device options across a range of case temperatures. The JBSFET is observed to display a reduction in peak turn-on current – up to 18.9% at 150°C and a significantly lesser turn-on switching loss – up to 46.6% at 150°C, compared to the SiC MOSFET. DA - 2019/// PY - 2019/// DO - 10.4028/www.scientific.net/MSF.963.797 VL - 963 MSF SE - 797-800 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071847000&partnerID=MN8TOARS ER - TY - CONF TI - The Influence of the LC with Clamping Diodes dv/dt Filter on Current Control of PMSM Drives in Case of Inverter Output Current Sensing and Its Compensation AU - Kim, H. AU - Kim, B.-H. AU - Bhattacharya, S. C2 - 2019/// C3 - ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia DA - 2019/// SP - 1280-1285 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071614124&partnerID=MN8TOARS ER - TY - CONF TI - State-space modeling and reachability analysis for a DC microgrid AU - Ghanbari, N. AU - Shabestari, P.M. AU - Mehrizi-Sani, A. AU - Bhattacharya, S. AB - In a DC microgrid containing parallel voltage sources, distributed control algorithms such as droop control methods are mainly employed. These controllers depend on the nominal bus voltage and the droop coefficients to operate properly. In the DC microgrid with PV arrays there are uncertainties in the PV current. To analyze the transient behavior of this uncertain system simulation-based techniques cannot be used, since they cannot consider the uncertainties. To analyze the uncertain DC microgrid, reachability analysis is used to find the limits of the system variables from a given state-space model of the system. In this paper, using the state-space model of the DC microgrid, reachability analysis is performed to analyze effectiveness of the droop control method in the existence of uncertainties. Simulation and experimental case studies are performed to verify the reachability analysis results. C2 - 2019/// C3 - Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC DA - 2019/// DO - 10.1109/APEC.2019.8721914 VL - 2019-March SP - 2882-2886 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85066759672&partnerID=MN8TOARS ER - TY - CONF TI - Single shot avalanche characterization of series and parallel connection of SiC power MOSFETs AU - Kumar, A. AU - Kokkonda, R.K. AU - Bhattacharya, S. AU - Veliadis, V. AB - Power modules are connected in series and parallel combinations to meet the voltage and current requirements of various applications, especially in medium voltage high power applications. Avalanche ruggedness of the SiC power MOSFETs need to be established in these connections to assess the reliability of the converters in extreme transient conditions. 1700 V SiC MOSFET has potential to replace the conventional 1700 V silicon IGBT in medium voltage power converters such as 800 V and 1500 V railway traction applications. In this paper, single shot avalanche ruggedness of the series-connected and parallel-connected 1700 V SiC MOSFETs are characterized using the unclamped inductive test circuit. Single shot avalanche ruggedness of series connected SiC MOSFETs is reported for the first time. In both the connections, the failed MOSFET was observed to be the one which dissipated lower share of the total avalanche energy of the connection. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998886 SP - 438-443 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081179636&partnerID=MN8TOARS ER - TY - CONF TI - Static, dynamic, and short-circuit performance of 1.2 kV 4H-SiC MOSFETs with various channel lengths AU - Han, K. AU - Kanale, A. AU - Baliga, B.J. AU - Bhattacharya, S. AB - The impact of channel length on the static, dynamic, and short-circuit performance of 1.2 kV-rated 4H-SiC inversion-channel (Inv) power MOSFETs is reported for the first time. Devices were successfully fabricated with the various channel lengths (L CH =0.3 to 1.1 μ m) in a 6 inch commercial foundry and they were packaged in TO-247 cases for all the testing. The devices with 0.3 μ m channel length were found to have the lowest on-resistance, best High Frequency Figures-of-Merit (HF-FOMs), and fastest switching performance, but worst short-circuit (SC) capability. The SC capability improved with increasing channel length at the penalty of an increase in the on-resistance. The fabricated 1.2 kV SiC MOSFETs were compared with commercially available 1.2 kV Si IGBTs in terms of the power losses and short-circuit capability: the 1.2 kV SiC power MOSFETs with long channel length can outperform the Si IGBT with lower power losses and superior short-circuit capability. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998803 SP - 47-52 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173165&partnerID=MN8TOARS ER - TY - CONF TI - Stability of 4H-SiC JBS Diodes under Repetitive Avalanche Stress AU - Kanale, A. AU - Han, K. AU - Jayant Baliga, B. AU - Bhattacharya, S. AB - Silicon carbide (SiC) Junction Barrier Schottky (JBS) rectifiers, used as antiparallel diodes for silicon IGBTs, can be subjected to high current reverse avalanche stress (RAS) during operation in inductive load circuits. The stability of commercially available and NCSU SiC JBS rectifiers was investigated after repetitive RAS. No degradation was observed after 10,000 RAS pulses at the rated on-state current level. Numerical Simulations reveal that the degradation of JBS diodes is suppressed because: (a) the electric field at the Schottky contact is reduced by P+ shielding region, (b) the avalanche current primarily flows via the P+ shielding region and not the Schottky contact, and (c) the temperature rise is limited to less than 100°C during the stress. The avalanche energy for failure of the diodes was also obtained for three values of load inductance by increasing the avalanche current. The critical failure energy was found to be independent of the load inductance values leading to a reduction of the failure current with increasing load inductance. C2 - 2019/// C3 - IEEE International Reliability Physics Symposium Proceedings DA - 2019/// DO - 10.1109/IRPS.2019.8720431 VL - 2019-March UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85066751469&partnerID=MN8TOARS ER - TY - CONF TI - Stability analysis of a medium voltage cascaded converter system with reduced DC-link capacitance AU - Acharya, S. AU - Anurag, A. AU - Bhattacharya, S. AB - Recent development of Silicon Carbide (SiC) based Medium Voltage (MV) power semiconductor devices have paved ways to build high power MV power converters with simple two level structures. One of the critical applications of these converters are solid state transformers (SSTs) which interconnects MV grid to a low voltage (LV) grid with high frequency isolation. SSTs are usually built with multi-stage cascaded conversion structures which includes ac-dc, dc-dc, and dc-ac stages, respectively. These converter structures need an intermediate MV DC bus to function. For MV applications, the DC bus structure is designed with low inductance bus bar and MV capacitors. At medium voltage levels, it is difficult to manufacture capacitors with high capacitance values with low footprint. Therefore, MV polypropylene film capacitors with low equivalent series inductance (ESL) are often utilized to build the MV DC Bus to meet the power density requirements. The small values of the effective DC bus capacitance create stability issues for cascaded converter structures for SSTs as it becomes difficult to completely decouple different power conversion stages. This paper delves into the interaction between different power conversion stages of a MV SST while transferring power. The study shows that low capacitance value of the MV DC bus can cause instability which needs to be mitigated. C2 - 2019/// C3 - Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC DA - 2019/// DO - 10.1109/APEC.2019.8722010 VL - 2019-March SP - 1157-1164 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85067128395&partnerID=MN8TOARS ER - TY - CONF TI - Shielding of Leakage Flux Induced Losses in High Power, Medium Frequency Transformers AU - Beddingfield, R.B. AU - Bhattacharya, S. AU - Ohodnicki, P. AB - Metal Amorphous Nanocrystalline core materials have shown great promise as the magnetic material for the isolation transformer used in high power, high frequency power converters. However, many current designs require special winding configurations that result in high parasitic capacitance. Similarly, when these designs are used in active bridge circuits where a certain minimum series inductance is required, auxiliary inductors are required. These dramatically reduce the power density and can have impacts on the efficiency. Designs that integrate the series inductance through inherently geometric approaches have resulted in catastrophic increases in losses that are not predicted by typical core magnetizing loss models and have not been viable as a result. This paper demonstrates a method of using a mix of materials to manage and direct the leakage flux through paths that are more efficient. Similarly, this approach enables deliberate tuning and design of the series inductance. This introduces a method to independently design the series inductance with the magnetizing inductance of the transformer. This will prove to enable high efficiency transformer designs with very high power density, empowering wide bandgap semiconductor-based converters to reach their full potential. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8911859 SP - 4154-4161 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076790212&partnerID=MN8TOARS ER - TY - JOUR TI - Small-signal stability assessment and active stabilization of a bidirectional battery charger AU - Iyer, Vishnu Mahadeva AU - Gulur, Srinivas AU - Bhattacharya, Subhashish T2 - IEEE Transactions on Industry Applications AB - A two-stage electric vehicle (EV) battery charger typically consists of an ac-dc converter cascaded with a dc-dc converter. In such a cascaded system, maintaining stability at the intermediate dc link is imperative for reliable operation of the battery charger under different operating modes. This paper addresses the intermediate dc-link stability challenges that exist in a bidirectional two-stage grid connected single-phase battery charger. It is delineated that the small-signal load-dependent resistance of the ac-dc converter plays a crucial role in determining the stability of the bidirectional battery charger. A virtual-resistor-based active damping control strategy that does not require any additional sensors is explored for the ac-dc converter to stabilize the cascaded system under all operating modes irrespective of the power flow direction. Experimental results on a grid-connected single-phase battery charger hardware prototype are presented to validate the proposed models and showcase the improvement in the dc-link stability due to the virtual-resistance-based active damping approach. DA - 2019/// PY - 2019/// DO - 10.1109/TIA.2018.2871101 VL - 55 IS - 1 SP - 563-574 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85053610599&partnerID=MN8TOARS KW - AC-DC power converters KW - active damping KW - active stabilization KW - battery charger KW - dual active bridge (DAB) KW - impedance modeling KW - small-signal modeling KW - stability KW - virtual resistance KW - voltage source converter (VSC) ER - TY - CONF TI - Modeling and Stability Assessment of Single-Phase Droop Controlled Solid State Transformer AU - Prabowo, Y. AU - Iyer, V.M. AU - Kim, B. AU - Bhattacharya, S. C2 - 2019/// C3 - ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia DA - 2019/// SP - 3285-3291 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071608538&partnerID=MN8TOARS ER - TY - CONF TI - Implementation of Flexible Large Power Transformers Using Modular Solid State Transformer Topologies Enabled by SiC Devices AU - Jakka, V.N. AU - Nath, H. AU - Acharya, S. AU - Kadavelugu, A. AU - Madhusoodhanan, S. AU - Tripathi, A. AU - Patel, D. AU - Mainali, K. AU - Bhattacharya, S. AB - Large power transformers (LPTs) have been a major concern of the electric power sector as a failure of a single unit can lead to temporary service interruption and utility damages. Replacement of such large and heavy transformer units is a challenging job as LPTs are custom-designed and hence entail long lead times due to its intricate manufacturing process and transportation. On the other hand, solid-state-transformer (SST) technology has evolved as an alternate option for the conventional line-frequency transformers, which offers comparatively reduced size and weight with the enhanced power quality features. With the advancement in wide-bandgap devices such as silicon carbide (SiC) and advanced power electronic converters, SSTs are able to deploy in medium voltage applications. Consequently, the utilization of SiC-SSTs for large power applications can mitigate some of the existing concerns of LPTs. In this paper, challenges and concerns associated with the existing LPTs are discussed. Possible SST modules/cells enabled by SiC devices, which can be connected in a modular structure to achieve multi-cell flexible large power SSTs (FLP-SST) are presented. The effectiveness of the discussed SST cells is validated using appropriate simulations and experimental results of the scaled SST prototypes. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912564 SP - 4619-4626 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076753041&partnerID=MN8TOARS ER - TY - BOOK TI - Experimental study of high-temperature switching performance of 1.2kv sic JBSFET in comparison with 1.2kv sic MOSFET AU - Kanale, A. AU - Jayant Baliga, B. AU - Han, K. AU - Bhattacharya, S. AB - The high-temperature switching performance of a 1.2kV SiC JBSFET is compared with a 1.2kV SiC MOSFET using a clamped inductive load switching circuit representing typical H-bridge inverters. The switching losses of the SiC MOSFET are also evaluated with a SiC JBS Diode connected antiparallel to it. Measurements are made with different high-side and low-side device options across a range of case temperatures. The JBSFET is observed to display a reduction in peak turn-on current – up to 18.9% at 150°C and a significantly lesser turn-on switching loss – up to 46.6% at 150°C, compared to the SiC MOSFET. DA - 2019/// PY - 2019/// DO - 10.4028/www.scientific.net/MSF.963.625 VL - 963 MSF SE - 625-628 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071889458&partnerID=MN8TOARS ER - TY - CONF TI - Mission profile based reliability analysis of a three-phase PV inverter considering the influence of high dv/dt on parasitic filter elements AU - Anurag, A. AU - Acharya, S. AU - Pal, S. AU - Bhattacharya, S. AB - Silicon Carbide (SiC) power semiconductor devices in medium voltage (MV) applications have facilitated the use of power converters at distribution voltage level. In these applications, the semiconductor devices are exposed to a high peak stress (of up to 15 kV) and a very high dv/dt (of up to 100 kV/μs). The increasing use of these power devices has made the effects of the parasitic elements in the filter more prominent, due to the high dv/dt experienced by the passive filter elements during device switching transients. The parasitic elements in the filter inductors causes an increased switching loss in the devices. This paper analyses the effect of these additional losses on the lifetime of the device. A thermal analysis based on a mission profile (solar irradiance and temperature) is provided to account for the additional junction temperature rise due to the high dv/dt and the parasitic filter elements. Rainflow counting method has been used to identify the mean and amplitude of each thermal cycle. An analytical device model and Palgrem Miner rule is used to quantify the damage in the device. Comparisons have been carried out on basis of lifetime, for cases with and without the influence of parasitic capacitances. This analysis can be helpful in validating the importance of the design of filter inductors in these MV applications. C2 - 2019/// C3 - Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC DA - 2019/// DO - 10.1109/APEC.2019.8721983 VL - 2019-March SP - 3490-3496 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85067114144&partnerID=MN8TOARS ER - TY - JOUR TI - MV Power Conversion Systems Enabled by High-Voltage SiC Devices [Happenings] AU - Bhattacharya, Subhashish T2 - IEEE Power Electronics Magazine AB - Reports on medium voltage (MV0 power conversion systems that are enabled by high-voltage silicon carbide (SiC) devices. Thanks to recent strides in power electronics research and the availability of high-voltage SiC power semiconductor devices, we can contemplate building a smart “solid-state transformer” to handle the demands of the smart grid. In electrical distribution systems, the transformers convert thousands of volts MV into lower voltages that can be safely used in homes and businesses. With emerging technologies in building and fabricating MV SiC-based power semiconductor devices, MV power conversion on a large-scale scenario seems feasible. While companies, such as Wolfspeed (CREE), General Electric, Infineon Technologies, Mitsubishi, and ROHM, continue to develop and improve these MV semiconductor devices, we at the FREEDM Systems Center are aiming at the application side of things to ensure a market for these power devices. DA - 2019/// PY - 2019/// DO - 10.1109/MPEL.2019.2947369 VL - 6 IS - 4 SP - 18-21 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85078522992&partnerID=MN8TOARS ER - TY - CONF TI - Impact of gate oxide thickness on switching and short circuit performance of 1200 v 4H-SiC inversion-channel MOSFETs AU - Agarwal, A. AU - Kanale, A. AU - Han, K. AU - Baliga, B.J. AU - Bhattacharya, S. AB - In this paper, we report successful fabrication of 1200 V 4H-SiC planar-gate inversion-channel power MOSFETs with 27 nm gate oxide thickness in a 6 inch commercial foundry. The static electrical characteristics, switching performance and short-circuit failure times for the 27 nm devices are compared with those of conventional 55 nm gate oxide devices. The specific on-state resistance of the 27 nm gate oxide devices at a gate voltage of 15 V was found to be 1.5x lower than the conventional 55 nm gate oxide devices at a gate bias of 20 V. The total switching energy loss (E tot ) for the 27 nm device with V gs of 15 V and V gs of 10 is approximately equal and 1.4x larger than the 55 nm case with V gs of 20 V. The short-circuit failure time (t sc ) for the 27 nm device is 1.4× better than 55 nm device at V gs of 10 V but 1.4× worse for V gs of 15 V. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998839 SP - 59-62 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081169610&partnerID=MN8TOARS ER - TY - CONF TI - Hybrid operation of a GaN-based three-level T-type inverter for pulse load applications AU - Pulakhandam, H. AU - Bhattacharya, S. AU - Byrd, T. AB - Pulsed-power loads are present in many industries such as defense, automotive, milling, etc. Performance benefits like reduced switching stress, lower losses, dV/dT, harmonic distortion, and smaller output filters have proven the viability of multi-level converters at medium voltages. Now, with the rise of Wide Bandgap (WBG) semiconductors, studies have shown their relevance at low voltages (<1000V). This study highlights a potential control issue with three-level converters for Pulsed-Load applications and demonstrates a novel modulation scheme as a solution. The converter actively switches between two-level (2L) and three-level (3L) operation to minimize neutral point (NP) deviation, output current distortion and may now increase overall system power density. This hybrid operation reduces the ripple current requirements for the DC bus capacitors. The NP deviation and current distortion of the Gallium Nitride (GaN) based T-type converter is compared with the conventional three-level (3L) control scheme for a continuous pulsed-load. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998812 SP - 378-383 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173145&partnerID=MN8TOARS ER - TY - CONF TI - Medium Voltage DC Bus Enabled by Series Connection of SiC Mosfet Based Three Port DC-DC Converters AU - Chattopadhyay, R. AU - Gulur, S. AU - Nair, V. AU - Bhattacharya, S. AU - Ohodnicki, P.R. AB - This paper presents development of Medium Voltage(MV) DC bus using series connection of Modular DC-DC Converter blocks. The MVDC bus is developed using Three Port Triple Active Bridge(TAB) DC-DC converter, which integrate Renewable Energy Sources(RES) and Energy Storages(ES). The TAB DC-DC converter units are three port high frequency transformer isolated phase shifted converters which integrate RES and ES with an output dc bus. Multiple of this DC-DC converter output dc buses can be connected in series to obtain a Medium Voltage DC Bus. The three port TAB converters for this series connection of converters, use 1200V & 1700V SiC Mosfets as switching devices with a three port high frequency transformer providing galvanic isolation among the three ports. In this paper, two laboratory prototypes of the three port TAB converters are connected in series to demonstrate MVDC bus(>2kV). Three port TAB converter, Gate Drivers for TAB converters, Three Port High Frequency transformer, along with independent power & voltage control for three port TAB Converter is discussed here in this paper with experimental verification. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8911893 SP - 6231-6238 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076790742&partnerID=MN8TOARS ER - TY - CONF TI - Medium Voltage Asynchronous Micro-grid Power Conditioning System Enabled by HV SiC Devices AU - Parashar, S. AU - Bhattacharya, S. C2 - 2019/// C3 - ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia DA - 2019/// SP - 1676-1681 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071638598&partnerID=MN8TOARS ER - TY - CONF TI - Hardware-In-The-Loop Implementation of a Grid Connected PV System AU - Ghanbari, N. AU - Bhattacharya, S. AB - This paper presents a methodology and algorithm for validating the performance of a grid connected Photovoltaic (PV) system. The paper also aims at observing irradiance change of PV arrays and its effect on the load side of the converter using real time simulation. With this real time platform, it is possible to evaluate the system behavior with the uncertainties exist in PV production and the controller performance in maintaining DC bus voltage fixed. The methodology uses OPAL-RT as the Hardware-In-The-Loop (HIL) platform to model the system by means of its MATLAB based library. The power electronic elements are directly implemented in FPGA part of OPAL-RT, while the controller and mathematical model of PV arrays are implemented in its CPU part. The HIL results are presented to show the effect of irradiance change on the system variables. The presented HIL simulation platform also offers a verification for the system control algorithm design. C2 - 2019/// C3 - 2019 IEEE Industry Applications Society Annual Meeting, IAS 2019 DA - 2019/// DO - 10.1109/IAS.2019.8912363 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076723972&partnerID=MN8TOARS ER - TY - JOUR TI - Exact Solution of ZVS Boundaries and AC-Port Currents in Dual Active Bridge Type DC-DC Converters AU - Shah, Suyash Sushilkumar AU - Iyer, Vishnu Mahadeva AU - Bhattacharya, Subhashish T2 - IEEE Transactions on Power Electronics AB - This letter presents an approach to develop an exact, unified model of zero voltage switching (ZVS) regions and ac-port currents (peak and RMS) in dual active bridge type dc-dc converters for all its operating modes and modulation strategies. It is executed for a single-phase system, where the method is used to compute closed-form expressions of ac current at switching instants. Then, exact formulae of ZVS regions for all devices, system peak, and RMS currents are derived. Simulation and hardware results for forward and reverse power transfer are reported to validate the proposed approach. DA - 2019/// PY - 2019/// DO - 10.1109/TPEL.2018.2884294 VL - 34 IS - 6 SP - 5043-5047 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85057892110&partnerID=MN8TOARS KW - AC current KW - bidirectional dc-dc converter KW - dual active bridge (DAB) KW - modeling KW - peak current KW - RMS current KW - soft switching KW - zero voltage switching (ZVS) KW - ZVS boundaries ER - TY - CONF TI - Effect of Inverter Output dv/dt with Respect to Gate Resistance and Loss Comparison with dv/dt Filters for SiC MOSFET based High Speed Machine Drive Applications AU - Kim, H. AU - Acharya, S. AU - Anurag, A. AU - Kim, B.-H. AU - Bhattacharya, S. AB - Fast switching characteristic of wide band gap (WBG) devices enables high frequency switching of power devices and thereby, facilitates high fundamental frequency operation of a machine. However, with the switching transition times being in orders of tens of nanoseconds, a high dv/dt is observed across the switching device. The high dv/dt experienced by the switches, and consequently by the machine, can degrade winding insulations or bearings over a period of time. It is therefore imperative to maintain dv/dt below recommended values depending on the machine insulation. The dv/dt across the devices can be adjusted by using higher values of gate resistance. However, this introduces additional switching losses on the device. Using different dv/dt filtering techniques can also help to control the dv/dt on the machine terminals. These techniques do not increase the switching losses on the device. However, the filter circuits introduce losses in the circuit and additional costs. In this paper, an analysis based on the impact of gate resistance on the dv/dt across the machine, and the corresponding losses is carried out. In addition, a comparision is performed on the basis of efficiency between these two techniques. A SiC MOSFET based 3-phase inverter (CREE-CCS020M12CM2) is used for the analysis. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912249 SP - 2301-2306 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076751560&partnerID=MN8TOARS ER - TY - JOUR TI - Design Considerations and Development of an Innovative Gate Driver for Medium-Voltage Power Devices With High dv/dt AU - Anurag, Anup AU - Acharya, Sayan AU - Prabowo, Yos AU - Gohil, Ghanshyamsinh AU - Bhattacharya, Subhashish T2 - IEEE Transactions on Power Electronics AB - Medium-voltage (MV) silicon carbide (SiC) devices have opened up new areas of applications which were previously dominated by silicon-based IGBTs. From the perspective of a power converter design, the development of MV SiC devices eliminates the need for series connected architectures, control of multilevel converter topologies which are necessary for MV applications, and the inherent reliability issues associated with it. However, when SiC devices are used in these applications, they are exposed to a high peak stress (5-10 kV) and a very high dv/dt (10-100 kV/μs). Using these devices calls for a gate driver with a dc-dc isolation stage that has ultralow coupling capacitance in addition to be able to withstand the high isolation voltage. This paper presents a new MV gate driver design to address these issues while maintaining a minimal footprint for the gate driver. An MV isolation transformer is designed with a low interwinding capacitance, while maintaining the clearance, creepage, as well as insulation standards. A dc isolation test has been performed to validate the integrity of the insulating material. The key features include low input common mode current, and a short-circuit protection scheme specifically designed for 10 kV SiC MOSFETs. The performance of the gate driver is evaluated using double pulse tests and continuous tests. Experimental results validate the advantages of the gate driver and its application for MV SiC devices exhibiting very high dv/dt. The proposed gate driver concept is aimed at providing an efficient and reliable method to drive MV SiC devices. DA - 2019/// PY - 2019/// DO - 10.1109/TPEL.2018.2870084 VL - 34 IS - 6 SP - 5256-5267 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85053299348&partnerID=MN8TOARS KW - Boost converter KW - buck converter KW - continuous tests KW - coupling capacitance KW - double pulse test KW - dv/dt immunity KW - gate driver KW - medium voltage (MV) KW - silicon carbide (SiC) devices ER - TY - CONF TI - Control of circulating current to minimize the rating of the energy storage device in modular multilevel converters AU - Alharbi, M. AU - Isik, S. AU - Bhattacharya, S. AB - The circulating current is a negative sequence current at double the fundamental frequency in a Modular Multilevel Converter (MMC). Conventionally, many types of research are conducted to suppress the circulating current in an MMC to reduce the converter loading. However, this paper studies rather than suppressing the circulating current, decoupling control algorithm between circulating current and AC, DC sides of the converter improves the average and RMS current such that performance of the converter increases while rating of the devices minimize. The Sub-Module (SM) capacitor voltage ripple significantly reduces so that the cost of a large scale MMC application decrease. The proposed control algorithm uses AC power as a circulating current reference, so the amplitude and phase of the output currents need not to be calculated. The studies are performed in Real Time Digital Simulator (RTDS) with FPGA based MMC support unit. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912773 SP - 6041-6045 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076773793&partnerID=MN8TOARS ER - TY - CONF TI - Efficient Power Transfer to Data Center Racks using Medium Voltage Inductive Coupling AU - Samanta, S. AU - Beddingfield, R. AU - Wong, I. AU - Bhattacharya, S. AB - Usually, the data center racks are supplied power at or below 400V, primarily due to safety. However, because of rapid increase in size of data centers, the power demand is also rising sharply, which results in bulky power cables and inefficient power distribution. In this paper, the idea of inductive coupling is used to increase the distribution voltage level to kVs, while maintaining the required safety aspects of the system. Based on the defined problem, a suitable converter topology is selected, where safety issue are addressed with a gapped-core (or split-core) transformer isolation. The performance of this converter circuit is analyzed, and component ratings are derived. Soft-switching performance of inverter devices are also reported. Due to low voltage and high current at the output, synchronous rectification technique promises significant improvement in efficiency. To verify the performances of the converter circuit, numerical simulation is performed in PowerSIM 11. A 2.5kW lab-prototype is developed, where the input/ output voltage is 1.1kV / 48V, and experimental results are included to justify the suitability of the selected converter. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8911899 SP - 1125-1130 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076792078&partnerID=MN8TOARS ER - TY - CONF TI - Design of modular auxiliary gate driver power supply for medium voltage converter system AU - Parashar, S. AU - Kokkonda, R. AU - Bhattacharya, S. AB - Auxiliary Power supplies are necessary for powering the gate drivers and controller circuits used in converter operation. Designing auxiliary power supplies for generating very low voltage output (up to 20V) from medium voltage DC input (6kV to 10kV) is technically challenging. Currently, lot of research is being carried out in implementing grid level medium voltage converters using 6.5kV to 10kV SiC MOSFETs. Fast switching speed of SiC devices induces common mode noise into the gate driver system. Apart from generating a DC output for gate drivers, the power supplies also need to provide the necessary isolation and common mode current protection resulting from fast switching. This paper discusses a novel power supply topology to generate an isolated low Voltage output from a high voltage input up to 2kV. A scheme has been proposed to achieve low DC output from Medium Voltage input (6kV to 10kV) by series input and parallel output connection of auxiliary power supply modules. Theoretical analysis of proposed topology has been formulated and hardware implementation has been done to verify operation of the topology. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912853 SP - 5712-5719 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076732434&partnerID=MN8TOARS ER - TY - CONF TI - Demonstration of new generation 10kV SiC MOSFET modules in medium voltage power converters AU - Parashar, S. AU - Kumar, A. AU - Jakka, V. AU - Bhattacharya, S. AU - Veliadis, V. AB - This paper reports a comprehensive analysis of three phase converter enabled by 10kV SiC based XHV-6 modules. A thorough explanation of converter based upon 10kV XHV-6 module has been carried out. The gate driver and converter structure used for carrying out the test have been explained in details. The assessment of MOSFET modules have been carried out in several steps till final implementation of three phase VSI (voltage source inverter). Step 1 involves double pulse test, which identifies the nominal Rg and switching losses for 10kV SiC MOSFET at specified current. Double pulse test is followed by continuous operation of single 10kV switch in buck-boost converter topology (Step 2). Operation of Single MOSFET switch in buck-boost topology 1) evaluates the capacity of modules for sustaining specified dv/dt without failure 2) provide the loss data for single MOSFET switch in continuous operation. After that, MOSFET modules are operated in Single pole configuration (building block for MV converters) as half bridge topology (Step 3) for evaluating their performance in terms of losses and dv/dt current (through base plates) for complementary switching. The single pole operation is demonstrated on 5:6kV voltage stress. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998836 SP - 208-213 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081173124&partnerID=MN8TOARS ER - TY - CONF TI - Evaluation of Extra High Voltage (XHV) Power Module for Gen3 10 kV SiC MOSFETs in a Mobile Utility Support Equipment based Solid State Transformer (MUSE-SST) AU - Anurag, A. AU - Acharya, S. AU - Bhattacharya, S. C2 - 2019/// C3 - ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia DA - 2019/// UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071614810&partnerID=MN8TOARS ER - TY - CONF TI - Design and Performance Evaluation of 1.2 kV, 325 a SiC-MOSFET High Performance Module Based 100 kVA Three-Phase Two-Level Power Block AU - Acharya, S. AU - Anurag, A. AU - Kolli, N. AU - Bhattacharya, S. C2 - 2019/// C3 - ICPE 2019 - ECCE Asia - 10th International Conference on Power Electronics - ECCE Asia DA - 2019/// SP - 821-828 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071642137&partnerID=MN8TOARS ER - TY - BOOK TI - Avalanche ruggedness characterization of 10 KV 4H-SIC MOSFETS AU - Kumar, A. AU - Parashar, S. AU - Brunt, E.V. AU - Sabri, S. AU - Ganguly, S. AU - Bhattacharya, S. AU - Veliadis, V. AB - In this paper, single pulse unclamped inductive switching (UIS) test of Wolfspeed Gen-3 10 kV, 15 A 4H-SiC MOSFETs is performed for four operating conditions at room temperature. The avalanche energy is observed to be around 7.0 J. The measured values are in good agreement with expected behavior, which may be extrapolated beyond the experimentally measured range. Failure analysis was conducted after each device failure to observe the failure locations. Avalanche parameters of SiC MOSFETs with various voltage ratings are compared. The avalanche energy of the Gen-3 10 kV, 15 A 4H-SiC MOSFETs is obtained to be superior to earlier generations of 10 kV SiC MOSFETs. DA - 2019/// PY - 2019/// DO - 10.4028/www.scientific.net/MSF.963.773 VL - 963 MSF SE - 773-776 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071879222&partnerID=MN8TOARS ER - TY - CONF TI - Accurate characterization and emulation of active bridge magnetic efficiencies with novel excitation circuit AU - Beddingfield, R.B. AU - Bhattacharya, S. AU - Ohodnicki, P. AB - Significant research has sought to understand, predict and map passive device performance for high power converters. Magnetic component performance is paramount for proper operation, efficiency and power density requirements. This paper introduces a method to apply the complex, multilevel operational waveforms needed for exact magnetic component performance mapping while using traditional open secondary testing techniques and a simple configuration of WBG devices. This converter easily achieves the high voltages and currents at high bandwidth that are applicable to advanced power converters. The presented testing approach reduces mischaracterization errors by up to 400%. An example characterization case of magnetics for the three port active bridge is shown whereby the transformer design efficiency is measured over the entire converter operational space. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8913154 SP - 4117-4124 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076794646&partnerID=MN8TOARS ER - TY - CONF TI - Benchmarking and qualification of gate drivers for medium voltage (MV) operation using 10 kV silicon carbide (SiC) MOSFETs AU - Anurag, A. AU - Acharya, S. AU - Gohil, G. AU - Bhattacharya, S. AB - Emergence of reliable medium voltage (MV) silicon carbide (SiC) devices, has made it possible to use these for MV applications, including grid interconnections, and medium voltage drives system. In a converter structure, the isolated power supplies of the gate drivers for these MV devices experience a peak stress up to 15 kV and a very high dv/dt (up to 100 kV/μs). Exposing the gate driver to such harsh conditions leads to various challenges in providing the required insulation, and maintaining the signal fidelity (due to common mode (CM) currents across the parasitic capacitance of the transformer). The failure of gate drivers at a converter level can lead to destructive damage to the converter. This calls for a methodology to design, test and qualify the gate drivers before implementing them in the field for long-term operation. This paper provides a detailed design methodology and analysis to qualify the gate drivers for a long-term operation. The analysis and design-phase ensures reliable operation of the gate driver, and the testing and qualifying phase ensures long-term operation of the gate driver. The experimental test setup has been built and test results have been provided based on a gate driver designed for 10 kV SiC MOSFETs. C2 - 2019/// C3 - Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC DA - 2019/// DO - 10.1109/APEC.2019.8721799 VL - 2019-March SP - 441-447 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85067126960&partnerID=MN8TOARS ER - TY - CONF TI - Battery State of Charge Management by Voltage Feedback Modification AU - Ghanbari, N. AU - Bhattacharya, S. AB - Due to increase in utilization of DC loads and renewable resources which mostly produce DC powers, there has been an increasing popularity in DC microgrids. In the previous research studies, the focus is more on power balancing among parallel voltage sources of the system while balancing the State of Charge (SoC) of batteries has been overlooked. In this paper, by modifying droop control method as the basis of power sharing in the DC microgrid, the objective of SoC equalization can be achieved. DC bus voltage scheduling is the core of modification to keep the batteries SoCs balanced. First, the paper discusses about an existing droop control based SoC balancing method with voltage scheduling. Then, it proposes a new DC bus voltage scheduling to overcome the drawback of the mentioned method. The methods have been simulated in MATLAB/Simulink and a comparison study has been performed. C2 - 2019/// C3 - ITEC 2019 - 2019 IEEE Transportation Electrification Conference and Expo DA - 2019/// DO - 10.1109/ITEC.2019.8790549 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071297175&partnerID=MN8TOARS ER - TY - CONF TI - Adaptive control of a hybrid energy storage system for wave energy conversion application AU - Agarwal, A. AU - Iyer, V.M. AU - Anurag, A. AU - Bhattacharya, S. AB - A hybrid energy storage system (HESS), that comprises of a battery and a supercapacitor, is utilized to absorb the power and energy oscillations for a wave energy conversion system so as to inject a smooth power to the grid. Continuous variation in the wave profile presents a formidable challenge in terms of the power and energy allocation among the battery and supercapacitor. In this paper, an adaptive control strategy is proposed, wherein the power and energy sharing between the battery and super-capacitor are dynamically decided based on an optimization algorithm. The proposed algorithm is aimed at optimizing the total losses in the hybrid energy storage system while simultaneously maximizing the battery lifetime. Circuit simulation and experimental results from a hardware prototype are provided to validate the effectiveness of the proposed control scheme. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912897 SP - 4994-5001 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076752081&partnerID=MN8TOARS ER - TY - CONF TI - Active voltage balancing methodology for series connection of 1700V SiC MOSFETs AU - Parashar, S. AU - Bhattacharya, S. AB - Series connection of 1.7kV Silicon Carbide (SiC) MOSFETs have potential to become a building block of compact and lightweight Megawatt power converters. These devices with high current carrying capability (56.5A/die) can be connected in series to develop high voltage and current rating power converters. Series connection of power devices generally involves passive voltage balancing methods, such as R-C snubbers, which increases the switching loss in power converters. Therefore, this paper describes the series connection of 1.7kV SiC MOSFETs using Active Voltage Balancing method. Active Voltage Balancing avoids R-C snubbers for minimizing voltage mismatch, thus reducing the switching loss in power converters. An alternative method of Active Voltage Balancing has been discussed in the paper for series connection of two 1.7kV SiC MOSFETs. The proposed method has been verified by simulation and experimental results. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998794 SP - 430-437 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081169018&partnerID=MN8TOARS ER - TY - CONF TI - An experimental study of short circuit behavior and protection of 15 kV SiC IGBTs AU - Kumar, A. AU - Bhattacharya, S. AU - Baliga, J. AU - Veliadis, V. AB - 15 kV SiC n-channel IGBTs have been successfully demonstrated earlier up to 10 kHz switching frequency in medium voltage (MV) power converters such as solid state transformer and transformerless intelligent power substation. Short circuit safe operating area (SC-SOA) of a power device is an essential requirement to assess the reliability of the converters. In this paper, for the first time, the short circuit (SC) behavior of the 15 kV SiC IGBT was investigated by a non-destructive experimental method under hard-switch fault (HSF) up to 8 kV dc bus. The high voltage output curve of the 15 kV SiC IGBT was obtained experimentally up to 8 kV in steps of 500 V. A TCAD model of the 15 kV IGBT was developed to understand the behavior of the IGBT in the current saturation region. The HV output characteristics was used in the estimation of the short circuit withstand time of the IGBT under HSF SC condition up to 12 kV dc bus. A desat diode based short circuit protection circuit was demonstrated successfully for the 15 kV IGBT. Performance of the desat protection circuit is compared with the 10 kV SiC MOSFETs. Behavior of the SiC IGBT in the saturation region was explained with the help of the TCAD model and the analytical equations. C2 - 2019/// C3 - 2019 IEEE 7th Workshop on Wide Bandgap Power Devices and Applications, WiPDA 2019 DA - 2019/// DO - 10.1109/WiPDA46397.2019.8998821 SP - 63-70 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85081171320&partnerID=MN8TOARS ER - TY - CONF TI - An active voltage stabilizer for a generic DC microgrid AU - Iyer, V.M. AU - Gulur, S. AU - Bhattacharya, S. AU - Kikuchi, J. AU - Sridharan, S. AU - Zou, K. AU - Chen, C. AB - This paper analyzes the low frequency stability chal-lenges that exist in a generic DC microgrid system. The conditions for system stability are derived from fundamental principles. A capacitive energy storage system based active voltage stabilizer, that handles the power fluctuations within the system during transient conditions, is proposed to stabilize the DC microgrid. The functionality of the active stabilizer, based on a bidirectional DC-DC converter, is elucidated and a suitable control strategy is proposed. The proposed active stabilizer and its associated control system involves only local voltage sensing and does not alter the generic DC microgrid structure. The proposed approach is validated through analytical models and circuit simulations. A dual active bridge (DAB) converter based active stabilizer is implemented and hardware based experimental results from a laboratory test-bench are provided to validate functionality and effectiveness of the proposed approach. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912949 SP - 462-468 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076730268&partnerID=MN8TOARS ER - TY - CONF TI - An Optimized SM Fault-Tolerant Control Method for MMC-based HVDC Applications AU - Alharbi, M. AU - Isik, S. AU - Bhattacharya, S. AB - Modular Multilevel Converters (MMCs) are becoming a realistic alternative to the conventional voltage source converters (VSCs) for medium voltage (MV) and high voltage direct current (HVDC) applications. The MMC topologies utilize a large number of submodules (SMs) cascaded in series per phase arm to achieve desired high voltage levels. These SMs can be as high as 512 to synthesize a very low total harmonic distortion (THD) (e.g. <; 0.1%) of the MMC AC side interface voltage. However, malfunction of any SM results in undesirable waveforms, and it may result in unstable operation of the entire MMC system. This paper proposes an optimized SM fault ride-through method and a capacitor voltage balancing (CVB) control for MMC-based HVDC applications. The proposed method can effectively improve the MMC performance and reliability under SM faults. The proposed approach is implemented in the Real-Time Digital Simulator (RTDS) and MMC support units based on FPGA boards. The results show that the proposed method can efficiently keep the MMC operation as normal and provide satisfactory performance under SM faults. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912483 SP - 1592-1597 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076736311&partnerID=MN8TOARS ER - TY - CONF TI - A Partial Power Converter Interface for Battery Energy Storage Integration with a DC Microgrid AU - Iyer, V.M. AU - Gulur, S. AU - Bhattacharya, S. AU - Ramabhadran, R. AB - A battery energy storage system (BESS) interface for a DC microgrid, featuring a partial rated power electronic converter, is proposed in this work. Universal schemes for implementing a partial rated BESS interface are discussed and a soft-switched, dual active bridge (DAB) converter-based solution is presented. The proposed scheme is analyzed and compared with a conventional full rated BESS interface converter to showcase its benefits. A control strategy that can enable multiple operating modes for the the partial rated power electronic BESS interface is discussed. Hardware prototypes of partial rated and full rated BESS interface converter solutions that are rated to transfer 3.3 kW to the BESS are developed and tested in the laboratory. Experimental evidence suggests that the partial rated BESS interface can improve the system efficiency by up to 3% while simultaneously reducing the converter rating by about 70% as compared to that of a full rated converter. Elimination of redundant power processing by the partial rated BESS interface offers tremendous potential to improve the efficiency and power density while drastically reducing the cooling overhead. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912590 SP - 5783-5790 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076744535&partnerID=MN8TOARS ER - TY - CONF TI - 50kW Nano-Crystalline Core Based Three Port Transformer for Triple Active Bridge Converter AU - Chattopadhyay, R. AU - Gulur, S. AU - Nair, V. AU - Bhattacharya, S. AU - Ohodnicki, P.R. AB - This paper discusses a 50kW high frequency three port transformer made of Nano-Crystalline core, for three port phase shifted DC-DC converter integrating Renewable Energy Sources(RES) & Energy Storages(ES). Phase shifted DC-DC converters need an isolating transformer with series inductances or leakage inductances for power transfer among different ports. However, using leakage inductances for a tape wound or Nano-Crystalline transformer as energy transferring element, causes high leakage fluxes to induce significant eddy currents & related losses in transformer cores. At high switching frequency, this eddy current losses can go too high, reducing efficiency. In order to avoid the eddy current losses in cores, an external inductor based approach along with the concentric winding transformer is presented in this paper for Three Port Phase Shifted Triple Active Bridge(TAB) converter. The three port converter can use either a three inductor or two inductor approach, which is discussed in this paper. The TAB converter uses 1.2kV & 1.7kV SiC Mosfets as switching devices along with Nano-Crystalline core based transformer & ferrite based series inductors. In this paper, analysis & design for concentric winding transformer and experimental results are presented. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912172 SP - 4167-4173 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076784147&partnerID=MN8TOARS ER - TY - CONF TI - A Novel Current Control Strategy Based on Harmonic Voltage Injection for Power Losses Reduction of PMSMs with Non-Sinusoidal Back-EMF AU - Kim, H. AU - Bhattacharya, S. AB - In terms of permanent magnet synchronous machine (PMSM) design, high power density and a low manufacturing cost can be achieved by sacrificing sinusoidal back-EMF. Those machines suffer from higher torque ripple due to the flux harmonics. Additionally, the non-sinusoidal back-EMF introduces current harmonics in the case where the conventional d-q axis current controller is adopted. This introduces additional copper losses in machine stator windings and conduction losses in inverter switches. A novel current control strategy based on harmonic voltage injection is presented for PMSMs with non-sinusoidal back-EMF to reduce the copper losses due to harmonic current components in a high speed region. Based on the harmonic back-EMF information of the machine, the harmonic voltages are injected to cancel out the harmonic components in the back-EMF waveforms so that machine current can be controlled with lower THD and copper losses. This method can be easily applied to the conventional PI current controller without non-sinusoidal coordinate transformation. C2 - 2019/// C3 - 2019 IEEE Industry Applications Society Annual Meeting, IAS 2019 DA - 2019/// DO - 10.1109/IAS.2019.8912372 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076759180&partnerID=MN8TOARS ER - TY - JOUR TI - A Dual-Loop Current Control Structure with Improved Disturbance Rejection for Grid-Connected Converters AU - Gulur, Srinivas AU - Iyer, Vishnu Mahadeva AU - Bhattacharya, Subhashish T2 - IEEE Transactions on Power Electronics AB - Increase in renewable energy penetration, in the recent past, has been one of the primary causes for serious issues in power quality of the utility grid. This has ushered in the need for a robust and stable control system for reference tracking and disturbance rejection of grid-connected converters. Conventionally, due to its simplicity and ability to achieve zero steady-state error, a simple proportional integral (PI) controller is used in the synchronous reference frame (dq) for current control of voltage-source based grid-connected systems. However, the PI controller by itself, may not suffice for adequate disturbance rejection, especially when the utility grid voltages contain other harmonics in addition to the fundamental component. This paper introduces and analyzes a dual-loop current control structure, which utilizes two independent controllers, one for reference tracking and the other for disturbance rejection in the dq frame. A small signal model of the dual-loop current control has been presented and its robustness under grid impedance variation, examined. Extensive experimental results are presented to validate the dual-loop control strategy for improved disturbance rejection capability and filtering action during the presence of grid voltage disturbances and grid impedance variations, without compromising the reference tracking performance. DA - 2019/// PY - 2019/// DO - 10.1109/TPEL.2019.2891686 VL - 34 IS - 10 SP - 10233-10244 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85068727943&partnerID=MN8TOARS KW - Current control KW - dq frame KW - grid-connected converters KW - grid impedance variations KW - grid voltage harmonics KW - inverter control KW - voltage-source inverters KW - voltage unbalances ER - TY - CONF TI - A DC circuit breaker with artificial zero current interruption AU - Singh, S. AU - Bhattacharya, S. AU - White, L.W. AB - A method for inducing a forced DC crossing applied to a Direct Current Circuit Breaker (DCCB) for High Voltage Direct Current (HVDC) applications is described. A low voltage prototype was developed, and theoretical analysis was done on the circuit to derive an expression for the fault clearance time. The circuit was modelled on PLECS for verification of the working principle. Hardware was fabricated for a 40 VDC, 2 A continuous current rating; the ideal analytical expression for fault clearance time was verified from the experimental value, which was observed to be 62.76 µs. Work described is covered by US Patent Publication No. 2017/0345587. C2 - 2019/// C3 - 2019 IEEE Energy Conversion Congress and Exposition, ECCE 2019 DA - 2019/// DO - 10.1109/ECCE.2019.8912956 SP - 1047-1051 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85076794399&partnerID=MN8TOARS ER - TY - CONF TI - A Robust and Reliable IEEE1547 Compliant Communication System for High Penetrated Renewable Energy Sources AU - Agashe, R. AU - Madadi, M. AU - Bhattacharya, S. AB - A novel and robust communication platform, compliant with IEEE 1547.3 has been developed for a distribution system with high penetrated renewable energy resources. The proposed communication system not only provides the realtime data monitoring through a designed web interface but also makes possible to remotely regulate the output voltage of all interconnected renewable energy resources. The effect of the communication latency on the performance of the designed hierarchical controllers of the interconnected renewable energy resources has been thoroughly investigated and the contributing parameters on improving the performance of the system has been determined. The result of this analysis could be used to optimize the system controller to minimize the voltage sag of the dc link capacitor and also improving the power system operational planning. The feasibility and reliability of the proposed communication platform has been validated by simulation and experimental results. C2 - 2019/// C3 - IEEE Power and Energy Society General Meeting DA - 2019/// DO - 10.1109/PESGM40551.2019.8973940 VL - 2019-August UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85079046983&partnerID=MN8TOARS ER - TY - CONF TI - A novel gate driver for active voltage balancing in 1.7kV series connected SiC MOSFETs AU - Parashar, S. AU - Bhattacharya, S. AB - This paper addresses active voltage balancing method for series connected 1.7 kV SiC MOSFETs. The series connection of 1.7 kV SiC MOSFETs have potential to replace medium voltage IGBTs (4.5 kV) due to their high switching speed and improved reliability. Series connection of SiC MOSFET is challenging due to possibility of voltage mismatch, voltage spike and device current spike in leg configuration. A novel gating technique has been introduced to reduce the voltage mismatch and voltage spike due to di/dt. Experimental results have been performed with series connection of two SiC MOSFETs and validated with theoretical calculations. C2 - 2019/// C3 - Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC DA - 2019/// DO - 10.1109/APEC.2019.8722176 VL - 2019-March SP - 2773-2779 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85067121601&partnerID=MN8TOARS ER - TY - JOUR TI - The role of cross-correlation between precipitation and temperature in basin-scale simulations of hydrologic variables AU - Seo, S.B. AU - Das Bhowmik, R. AU - Sankarasubramanian, A. AU - Mahinthakumar, G. AU - Kumar, M. T2 - Journal of Hydrology AB - Uncertainty in climate forcings causes significant uncertainty in estimating streamflow and other land-surface fluxes in hydrologic model simulations. Earlier studies primarily analyzed the importance of reproducing cross-correlation between precipitation and temperature (P-T cross-correlation) using various downscaling and weather generator schemes, leaving out how such biased estimates of P-T cross-correlation impact streamflow simulation and other hydrologic variables. The current study investigates the impacts of biased P-T cross-correlation on hydrologic variables using a fully coupled hydrologic model (Penn-state Integrated Hydrologic Model, PIHM). For this purpose, a synthetic weather generator was developed to generate multiple realizations of daily climate forcings for a specified P-T cross-correlation. Then, we analyzed how reproducing/neglecting P-T cross-correlation in climate forcings affect the accuracy of a hydrologic simulation. A total of 50 synthetic data sets of daily climate forcings with different P-T cross-correlation were forced into to estimate streamflow, soil moisture, and groundwater level under humid (Haw River basin in NC, USA) and arid (Lower Verde River basin in AZ, USA) hydroclimate settings. Results show that climate forcings reproducing the P-T cross-correlation yield lesser root mean square errors in simulated hydrologic variables (primarily on the sub-surface variables) as compared to climate forcings that neglect the P-T cross-correlation. Impacts of P-T cross-correlation on hydrologic simulations were remarkable to low flow and sub-surface variables whereas less significant to flow variables that exhibit higher variability. We found that hydrologic variables with lower internal variability (for example: groundwater and soil-moisture depth) are susceptible to the bias in P-T cross-correlation. These findings have potential implications in using univariate linear downscaling techniques to bias-correct GCM forcings, since univariate linear bias-correction techniques reproduce the GCM estimated P-T cross-correlation without correcting the bias in P-T cross-correlation. DA - 2019/3// PY - 2019/3// DO - 10.1016/J.JHYDROL.2018.12.076 VL - 570 SP - 304-314 J2 - Journal of Hydrology LA - en OP - SN - 0022-1694 UR - http://dx.doi.org/10.1016/J.JHYDROL.2018.12.076 DB - Crossref KW - Cross-correlation KW - GCM KW - Univariate KW - Bias-correction KW - PIHM KW - Hydrologic simulation ER - TY - CHAP TI - Key issue, challenges, and status quo of models for biofuel supply chain design AU - Lan, K. AU - Park, S. AU - Yao, Y. T2 - Biofuels for a More Sustainable Future: Life Cycle Sustainability Assessment and Multi-Criteria Decision Making AB - Biofuel supply chain (BSC) design is crucial for the sustainable production and distribution of biofuel. Many modeling techniques such as optimization and simulation have been employed to BSC at different regional and temporal scales. This chapter reviews the research efforts made in BSC since 2005 to highlight status quo, challenges, and issues related to BSC modeling and design. The basic concept and components of BSC are first introduced and followed by the review of different modeling techniques at various decision levels of BSC design. Challenges and issues identified throughout this review work are highlighted at the end and future research directions are discussed. PY - 2019/// DO - 10.1016/B978-0-12-815581-3.00010-5 SP - 273-315 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85083223493&partnerID=MN8TOARS ER - TY - JOUR TI - Integrating Life Cycle Assessment and Agent-Based Modeling: A Dynamic Modeling Framework for Sustainable Agricultural Systems AU - Lan, K. AU - Yao, Y. T2 - Journal of Cleaner Production AB - As food demand increases, it is critical to develop effective strategies and evaluate their potential in reducing Greenhouse Gas (GHG) emissions and other environmental footprints of large-scale agricultural systems. This study addresses the challenge by developing a dynamic system modeling framework integrating Life Cycle Assessment (LCA), Agent-Based Modeling (ABM), and Techno-Economic Analysis (TEA). LCA and TEA were coupled with dynamic simulation models of crop yields, costs, and prices, allowing for the estimation of life-cycle environmental impacts and profitability of crop planting activities under changing climate and economic conditions. The framework was demonstrated by a case study for an agricultural system, including 1,000 farms in the United States over a 30-year time frame. The results indicated that information exchange among farmers, farmers' environmental awareness, access to environmental information, and farm size are key factors driving the system's environmental impacts. The results can provide a broad range of stakeholders (e.g., policymakers, nonprofits, agriculture companies) with insightful information to tailor their strategies for effectively managing the environmental footprints of large-scale agricultural systems. The integrated modeling framework has the potential to address sustainability challenges in other systems that are dynamic, involve human behaviors, and have complex interactions among human and nature systems. DA - 2019/// PY - 2019/// DO - 10.1016/j.jclepro.2019.117853 VL - 238 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85073700439&partnerID=MN8TOARS KW - Life Cycle Assessment KW - Agent-based modeling KW - Dynamic modeling KW - Crop cultivation KW - Stochastic process ER - TY - JOUR TI - Life Cycle Analysis of Decentralized Preprocessing Systems for Fast Pyrolysis Biorefineries with Blended Feedstocks in the Southeastern United States AU - Lan, K. AU - Ou, L. AU - Park, S. AU - Kelley, S.S. AU - Yao, Y. T2 - Energy Technology AB - Blending biomass feedstock is a promising approach to mitigate supply chain risks that are common challenges for large‐scale biomass utilization. Understanding the potential environmental benefits of biofuels produced from blended biomass and identifying driving parameters are critical for the supply chain design. Herein, a cradle‐to‐gate life cycle analysis model for fast pyrolysis biorefineries converting blended feedstocks (pine residues and switchgrass) with traditional centralized and alternative decentralized preprocessing sites, so‐called depots, is explained. Different scenarios are developed to investigate the impacts of parameters such as feedstock blending ratios, biorefinery and depot capacities, preprocessing technologies, and allocation methods. The life‐cycle energy consumption and global warming potential (GWP) of biofuel production with depots vary between 0.7–1.1 MJ MJ −1 and 43.2–76.6 g CO 2 eq. MJ −1 , respectively. The results are driven by biorefinery processes and depot preprocesses. A decentralized design reduces the energy consumption of the biorefinery but increases the overall life‐cycle energy and GWP. Such increases can be significantly mitigated by increasing switchgrass content as the energy consumption at the depot is driven largely by the higher moisture content of pine feedstocks. Allocation methods also have a large impact on the results but do not change the major trends and overall conclusions. DA - 2019/// PY - 2019/// DO - 10.1002/ente.201900850 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071757907&partnerID=MN8TOARS KW - biorefineries KW - blended feedstocks KW - depots KW - fast pyrolysis KW - life cycle assessments KW - preprocessing sites ER - TY - JOUR TI - Using a Data-Driven Approach to Unveil Greenhouse Gas Emission Intensities of Different Pulp and Paper Products AU - Nabinger, A. AU - Tomberlin, K. AU - Venditti, R. AU - Yao, Y. T2 - Procedia CIRP AB - Life Cycle Assessment (LCA) has been used to evaluate the life-cycle Greenhouse Gas (GHG) emissions of pulp and paper production, and most previous studies rely on process-based models for specific product types (e.g., printing paper), industry-average data, or information from a few mills. In this work, a data-driven approach is used to quantify GHG emissions intensities of different paper products manufactured by the U.S. mills. Facility-level emission data collected from publically available governmental databases and mill-level production data collected from the private sector were integrated to track the GHG emissions for different product lines and paper products in mills (in total, 165 mills were matched and analyzed). The results highlight the ranges of GHG emissions intensities by different product groups and categories, and can be used as a transparent data source for LCA practitioners, policymakers, and the pulp and paper industry to perform further analysis on carbon accounting and strategic planning for GHG mitigation. DA - 2019/1// PY - 2019/1// DO - 10.1016/j.procir.2018.12.001 VL - 80 SP - 689-692 UR - http://dx.doi.org/10.1016/j.procir.2018.12.001 KW - pulp and paper industry KW - GHG emissions KW - carbon accounting KW - data-driven approach ER - TY - JOUR TI - A Parametric Life Cycle Modeling Framework for Identifying Research Development Priorities of Emerging Technologies: A Case Study of Additive Manufacturing AU - Yao, Y. AU - Huang, R. T2 - Procedia CIRP AB - Life Cycle Assessment (LCA) has been used to assess the environmental implications of emerging technologies in different manufacturing sectors. However, it is challenging to use the traditional LCA method to model the relationships between Life Cycle Inventory (LCI) data and key technical parameters, preventing further analysis for understanding key driving factors and determining priorities for research and technology development. Furthermore, the sensitivity analysis of traditional LCA could be misleading for decision making or strategic planning given that the potential/possibility of improving specific parameters are commonly not taken into consideration. In this work, a novel parametric analysis framework was developed to address the methodological challenge. The modeling framework integrates process-based engineering models with LCA, Life Cycle Cost analysis (LCC), and optimization. The framework is demonstrated through a case study of additive manufacturing (AM). DA - 2019/5// PY - 2019/5// DO - 10.1016/j.procir.2019.01.037 VL - 80 SP - 370-375 UR - http://dx.doi.org/10.1016/j.procir.2019.01.037 KW - parametric life cycle assessment KW - emerging technology KW - optimization KW - life cycle cost analysis KW - additive manufacturing ER - TY - JOUR TI - A new solution to mitigate hydropeaking? Batteries versus re-regulation reservoirs AU - Anindito, Yoga AU - Haas, Jannik AU - Olivares, Marcelo AU - Nowak, Wolfgang AU - Kern, Jordan T2 - JOURNAL OF CLEANER PRODUCTION AB - Hydropower plants frequently operate at high output during peak hours and at low output (or even shutoff) during off-peak hours. This scheme, called “hydropeaking”, is harmful to downstream ecosystems. Operational constraints (minimum flows, maximum ramps) are frequently used to mitigate the impacts of hydropeaking. However, they reduce the operational flexibility of hydroelectric dams and increase the operational cost of power systems. Another approach to mitigating ecological impacts from hydropeaking is using structural measures, such as re-regulation reservoirs or afterbays. The first contribution of our work is to study the cost-effectiveness of these re-regulation reservoirs in mitigating ecological impacts from subdaily hydropeaking. Our second contribution is assessing energy storage (specifically, batteries) to mitigate the financial impacts of implementing peaking restrictions on dams, which represents the first attempt in the literature. Understanding these mitigation options is relevant for new hydropower dams, as well as for existing ones undergoing relicensing processes. For this, we formulate an hourly mixed-integer linear optimization model to simulate the annual operation of a power system. We then compare the business-as-usual (unconstrained) hydropower operations with ecologically constrained operations. The constrained operation, by limiting hydropower ramping rates, showed to obtain flows close to the natural streamflow regime. As next step, we show how re-regulation reservoirs and batteries can help to achieve these ecological constraints at lower costs. While the former are cost-effective for a very broad range of investment costs, the latter will be cost-effective for hydropeaking mitigation from 2025 onwards, when their capital costs have fallen. If more stringent environmental constraints are imposed, both solutions become significantly more attractive. The same holds for scenarios of more renewable generation (in which the operational flexibility from both alternatives becomes more valuable). After 2030, batteries can match the cost-effectiveness of expensive re-regulation reservoirs. Our findings are valuable for policy and decision makers in energy and ecosystem conservation. DA - 2019/2/10/ PY - 2019/2/10/ DO - 10.1016/j.jclepro.2018.11.040 VL - 210 SP - 477-489 SN - 1879-1786 KW - Hydrological alteration KW - Richard baker flashiness index KW - Battery energy storage KW - Ecosystems KW - Rivers and streams ER - TY - JOUR TI - Numerical Study of Balancing between Indoor Building Energy and Outdoor Thermal Comfort with a Flexible Building Element AU - Kwon, Choul Woong AU - Lee, Kang Jun AU - Cho, Soolyeon T2 - SUSTAINABILITY AB - This study analyzed the environmental role of a flexible canopy as a microclimate modifier in balancing indoor energy demands and outdoor thermal comfort. Flexible building elements are often installed in traditional buildings, depending on the local climate in southern Europe. The architectural performance of a canopy was analyzed using several environmental software packages (Ecotect, Rayman, WinAir, DaySim, and EDSL TAS). Coupling methods were applied to determine the environmental influence of the attached building element, a canopy with fixed and operable panes in different orientations and locations. The results showed that the flexible canopy played a crucial role in reducing indoor energy demands (heating and electricity for lighting) and increasing outdoor thermal comfort under the canopy area. Outdoor thermally comfortable conditions ranging between 13 and 29 °C in the canopy space could be enhanced by 56.3% over the entire year by manipulating a flexible canopy, compared with a fixed canopy with 90% transparency in London. The flexible canopy with higher transparency helped increase outdoor thermal comfort in Glasgow, while one with lower transparency showed better performance during summer in London. The findings of this research will help broaden the range of architectural elements used in buildings. DA - 2019/12// PY - 2019/12// DO - 10.3390/su11236654 VL - 11 IS - 23 SP - SN - 2071-1050 KW - flexible canopy KW - outdoor thermal comfort KW - daylighting KW - heating energy demand KW - balancing energy KW - coupling method ER - TY - JOUR TI - Application of Artificial Neural Network for the Optimum Control of HVAC Systems in Double-Skinned Office Buildings AU - Seo, Byeongmo AU - Yoon, Yeo Beom AU - Mun, Jung Hyun AU - Cho, Soolyeon T2 - ENERGIES AB - Double Skin Façade (DSF) systems have become an alternative to the environmental and energy savings issues. DSF offers thermal buffer areas that can provide benefits to the conditioned spaces in the form of improved comforts and energy savings. There are many studies conducted to resolve issues about the heat captured inside DSF. Various window control strategies and algorithms were introduced to minimize the heat gain of DSF in summer. However, the thermal condition of the DSF causes a time lag between the response time of the Heating, Ventilation, and Air-Conditioning (HVAC) system and cooling loads of zones. This results in more cooling energy supply or sometimes less than required, making the conditioned zones either too cold or warm. It is necessary to operate the HVAC system in consideration of all conditions, i.e., DSF internal conditions and indoor environment, as well as proper DSF window controls. This paper proposes an optimal air supply control for a DSF office building located in a hot and humid climate. An Artificial Neural Network (ANN)-based control was developed and tested for its effectiveness. Results show a 10.5% cooling energy reduction from the DSF building compared to the non-DSF building with the same HVAC control. Additionally, 4.5% more savings were observed when using the ANN-based control. DA - 2019/12/2/ PY - 2019/12/2/ DO - 10.3390/en12244754 VL - 12 IS - 24 SP - SN - 1996-1073 KW - Double Skin Facade KW - HVAC optimal control KW - EnergyPlus KW - load prediction KW - artificial neural network ER - TY - JOUR TI - Do commercial buildings become less efficient when they provide grid ancillary services? AU - Keskar, Aditya AU - Anderson, David AU - Johnson, Jeremiah X. AU - Hiskens, Ian A. AU - Mathieu, Johanna L. T2 - Energy Efficiency DA - 2019/4/2/ PY - 2019/4/2/ DO - 10.1007/S12053-019-09787-X J2 - Energy Efficiency LA - en OP - SN - 1570-646X 1570-6478 UR - http://dx.doi.org/10.1007/S12053-019-09787-X DB - Crossref KW - Ancillary services KW - Energy efficiency KW - Commercial buildings KW - HVAC KW - Building controls KW - Demand response ER - TY - JOUR TI - A Study on Utility of Retrofit that Minimizes the Replacement of Heat-Source System in Large Offices AU - Kim, Hyemi AU - Park, Kyung-soon AU - Cho, Soolyeon AU - Song, Young-hak T2 - ENERGIES AB - In a general building retrofit process, the reinforcement of insulation performance or air-tightness in walls and windows are conducted to reduce the maximum cooling and heating load of buildings. A heat source consists of heat-source equipment and water-pipe systems, which are replaced with high-efficient specification materials. Most of them are simply replaced with the same capacity as the previous heating equipment. This study aims to investigate matters required for decision making in a retrofit plan, such as conducting an investigation of the maximum load reduction in buildings obtained by the retrofit and the capacity of heat-source equipment that reflects the reduction, and the re-use or replacement of the water-pipe system, etc. in advance. This study verified that when the capacity of heat-source equipment was reduced, the pipe diameter of the water-pipe system was also decreased, but if existing pipes were re-used, the transportation power of the pump was reduced due to the reduction in flow velocity. The changes in maximum cooling and heating load through retrofit were quantitatively verified compared to that of the initial design of the building based on previous study results, and flow rates of cool and hot water were determined by re-calculating the capacity of the heat-source equipment. Using the results, the water-pipe system was re-designed, and the annual transportation power of the pump was calculated through simulations. The calculation results verified that the transportation power decreased by up to approximately 10% when oversized pipes were re-used from the existing water-pipe system. Additionally, when the capacity of the heat-source equipment was decreased, reasonable measures considering remodeling, construction duration, and cost were derived. DA - 2019/11/2/ PY - 2019/11/2/ DO - 10.3390/en12224309 VL - 12 IS - 22 SP - SN - 1996-1073 KW - retrofit KW - replacing KW - downsizing KW - heat source system KW - office building ER - TY - JOUR TI - Positive water linkages of producing short rotation poplars and willows for bioenergy and phytotechnologies AU - Zalesny, Ronald S., Jr AU - Berndes, Göran AU - Dimitriou, Ioannis AU - Fritsche, Uwe AU - Miller, Constance AU - Eisenbies, Mark AU - Ghezehei, Solomon AU - Hazel, Dennis AU - Headlee, William L. AU - Mola‐Yudego, Blas AU - Negri, M. Cristina AU - Nichols, Elizabeth Guthrie AU - Quinn, John AU - Shifflett, Shawn Dayson AU - Therasme, Obste AU - Volk, Timothy A. AU - Zumpf, Colleen R. T2 - Wiley Interdisciplinary Reviews: Energy and Environment AB - The production of short rotation woody crops (SRWCs) such as poplars and willows is a promising component of global bioenergy and phytotechnology portfolios. In addition to the provision of biomass feedstocks and pollution remediation, these trees and shrubs have been sustainably grown to conserve or utilize water in a variety of applications. Growing these woody plants for multiple uses supports many of the United Nation's Sustainable Development Goals (SDGs), especially Clean Water and Sanitation (SDG6) and Affordable and Clean Energy (SDG7). As a result, focusing on ecosystem services such as freshwater and biomass has become an important aspect of deploying these production systems across variable landscapes. The current review consists of an introduction of ecosystem services and the SDGs, as well as SRWCs and their applications. The middle section of the review contains case studies highlighting the positive water linkages of producing short rotation poplars and willows for bioenergy and phytotechnologies. The review concludes with a section that combines the common themes that are consistent among the case studies to address options for integrating new bioenergy feedstock production systems into rural and urban landscapes to promote environmental, social and economic sustainability. This article is categorized under: Bioenergy > Economics and Policy Bioenergy > Climate and Environment DA - 2019/4/11/ PY - 2019/4/11/ DO - 10.1002/WENE.345 VL - 8 IS - 5 J2 - WIREs Energy Environ. LA - en OP - SN - 2041-8396 2041-840X UR - http://dx.doi.org/10.1002/WENE.345 DB - Crossref KW - biomass production KW - ecosystem services KW - phytoremediation KW - sustainable development goals KW - water management ER - TY - JOUR TI - Expanding phytoremediation to the realms of known and unknown organic chemicals of concern AU - Hedgespeth, Melanie L. AU - Nichols, Elizabeth Guthrie T2 - International Journal of Phytoremediation AB - Recent advancements in analytical chemistry and data analyses via high-resolution mass spectrometry (HRMS) are evolving scientific understanding of the potential totality of organic chemical exposure and pollutant risk. This review addresses the importance of HRMS approaches, namely suspect screening and nontarget chemical analyses, to the realm of phytoremediation. These analytical approaches are not without caveats and constraints, but they provide an opportunity to understand in greater totality how plant-based technologies contribute, mitigate, and reduce organic chemical exposure across scales of experimental and system-level studies. These analytical tools can enlighten the complexity and efficacy of plant-contaminant system design and expand our understanding of biogenic and anthropogenic chemicals at work in phytoremediation systems. Advances in data analytics from biological sciences, such as metabolomics, are crucial to HRMS analysis. This review provides an overview of targeted, suspect screening, and nontarget HRMS approaches, summarizes the expanding knowledge of regulated and unregulated organic chemicals in the environment, addresses requisite HRMS instrumentation, analysis cost, uncertainty, and data processing techniques, and offers potential bridges of HRMS analyses to phytoremediation research and application. DA - 2019/7/1/ PY - 2019/7/1/ DO - 10.1080/15226514.2019.1633265 VL - 21 IS - 14 SP - 1385-1396 J2 - International Journal of Phytoremediation LA - en OP - SN - 1522-6514 1549-7879 UR - http://dx.doi.org/10.1080/15226514.2019.1633265 DB - Crossref KW - HRMS KW - organic contaminant KW - nontarget KW - phytoremediation KW - exposome KW - pollutome ER - TY - JOUR TI - Suspect screening and prioritization of chemicals of concern (COCs) in a forest-water reuse system watershed AU - Hedgespeth, Melanie L. AU - Gibson, Nancy AU - McCord, James AU - Strynar, Mark AU - Shea, Damian AU - Nichols, Elizabeth Guthrie T2 - Science of The Total Environment AB - Much research has assessed organic chemicals of concern (COCs) in municipal wastewater and receiving waters, but few studies have examined COCs in land treatment systems. Many prior studies have implemented targeted methods that quantify a relatively small fraction of COCs present in wastewater and receiving waters. This study used suspect screening to assess chemical features in ground- and surface waters from a watershed where secondary-treated wastewater is irrigated onto 900 ha of temperate forest, offering a more holistic view of chemicals that contribute to the exposome. Chemical features were prioritized by abundance and ToxPi scoring across seasonal sampling events to determine if the forest-water reuse system contributed to the chemical exposome of ground- and surface waters. The number of chemical features detected in wastewater was usually higher than on- and off-site ground- and surface waters; in wastewater, chemical features trended with precipitation in which greater numbers of features were detected in months with low precipitation. The number of chemical features detected in off- and on-site waters was similar. The lower overlap between chemical features found in wastewater and downstream surface waters, along with the similar numbers of features being detected in upstream and downstream surface waters, suggests that though wastewater may be a source of chemicals to ground and surface waters on-site, dissipation of wastewater-derived features (in number and peak area abundance) likely occurs with limited off-site surface water export by the forested land treatment system. Further, the numbers of features detected on site and the overlap between wastewater and surface waters did not increase during periods of low rainfall, counter to our initial expectations. The chemical features tentatively identified in this watershed appear common to features identified in other studies, warranting further examination on the potential for resulting impacts of these on humans and the environment. DA - 2019/12// PY - 2019/12// DO - 10.1016/j.scitotenv.2019.07.184 VL - 694 SP - 133378 J2 - Science of The Total Environment LA - en OP - SN - 0048-9697 UR - http://dx.doi.org/10.1016/j.scitotenv.2019.07.184 DB - Crossref KW - HRMS KW - Suspect screening KW - Wastewater KW - Forest KW - Exposome ER - TY - JOUR TI - Productivity and cost-effectiveness of short-rotation hardwoods on various land types in the southeastern USA AU - Ghezehei, Solomon B. AU - Nichols, Elizabeth G. AU - Hazel, Dennis W. T2 - International Journal of Phytoremediation AB - Despite the growing need to produce energy crops, information on comprehensive feasibility of growing short-rotation woody crops (SRWCs) on non-contentious and less-utilized lands and lands transitioning from previous uses in the southeastern USA is limited. An assessment model (SRWC-PEAM) was developed and tested for assessing the feasibility of SRWCs on lands targeted for ecosystem-service enhancements based on land conditions, species, and stand and economic variables in the southeastern USA. Productivity and economic returns of sweetgum (Liquidambar styraciflua L.), sycamore (Platanus occidentalis L.), and poplar (Populus) stand differed due to land types, species' adaptability and biomass potential, and optimal land-type-based management schemes. Poplar stands had the greatest biomass and the highest returns on all land types although returns from the three species on most land types were poor using current reported regional delivered prices. Irrigating stands increased yields but returns were poorer than from non-irrigated stands due to high costs of irrigation. Longer rotations resulted in greater biomass and returns and were more crucial for irrigated stands. Significantly higher feedstock prices and productivities are requisite for SRWC viability in the southeastern USA. SRWC-PEAM is a web-based tool and can accommodate other SRWC species and assessment of environmental services associated with SRWCs. DA - 2019/8/9/ PY - 2019/8/9/ DO - 10.1080/15226514.2019.1647404 VL - 22 IS - 1 SP - 98-110 J2 - International Journal of Phytoremediation LA - en OP - SN - 1522-6514 1549-7879 UR - http://dx.doi.org/10.1080/15226514.2019.1647404 DB - Crossref KW - Ecosystem services KW - enterprise budget KW - investment analysis KW - optimum stand management KW - site quality rating KW - SRWC-PEAM ER - TY - JOUR TI - Performance analysis of a double-skin facade system installed at different floor levels of high-rise apartment building AU - Yoon, Yeo Beom AU - Seo, Byeongmo AU - Koh, Brian Baewon AU - Cho, Soolyeon T2 - JOURNAL OF BUILDING ENGINEERING AB - This paper introduces a Double Skin Façade (DSF) system that can be installed in existing apartments in South Korea as a replacement of poorly performing old balcony windows. The DSF system can bring thermal benefits, especially in heating dominant climate areas. The DSF system works as a thermal buffer area and passive heating system. The goal of this research is to evaluate the thermal performance of a DSF system installed in apartments at different floor levels. A typical 25-story apartment building is used as a case study to test the thermal performance of a DSF system in different floors. Heating energy savings are the focus since the location, Seoul, is a heating dominant climate area. The main parameters are temperature, wind speed, and pressure differences at different floor levels. A thermal simulation model for a Base-Case is developed and calibrated to measured data gathered from a real-scale DSF system physical model. Two other simulation models are developed on top of the Base-Case model to compare performances of the DSF system installed in apartments at different floor levels. Results show that the first floor apartment unit consumes the least heating energy and the 25th floor the most, as expected. The outside air temperature difference between the first floor and the 25th floor was about 0.4 °C. The results also show the largest heating energy savings of 30% in the 21st floor with the installation of the DSF system. DA - 2019/11// PY - 2019/11// DO - 10.1016/j.jobe.2019.100900 VL - 26 SP - SN - 2352-7102 KW - Double skin facade KW - Retrofitting KW - High-rise apartment KW - Floor levels KW - Building simulation ER - TY - JOUR TI - Tree Water Use, Water Use Efficiency, and Carbon Isotope Discrimination in Relation to Growth Potential in Populus deltoides and Hybrids under Field Conditions AU - Maier, Christopher A. AU - Burley, Joel AU - Cook, Rachel AU - Ghezehei, Solomon B. AU - Hazel, Dennis W. AU - Nichols, Elizabeth G. T2 - FORESTS AB - We explored the relationship between tree growth, water use, and related hydraulic traits in Populus deltoides Bartr. ex Marsh.and hybrid clones, to examine potential trade-offs between growth and water use efficiency. Nine genotypes, six P. deltoides and three hybrid clones, that represented genotypes with high (Group H), intermediate (Group I), and low (Group L) growth performance were selected for study, based on year-two standing stem biomass in a replicated field trial. In year four, tree growth, transpiration (Et), canopy stomatal conductance (Gs), whole-tree hydraulic conductance (Gp), and carbon isotope discrimination (Δ13C) were measured. Tree sap flux was measured continuously using thermal dissipation probes. We hypothesized that Group H genotypes would have increased growth efficiency (GE), increased water use efficiency of production (WUEp, woody biomass growth/Et), lower Δ13C, and greater Gp than slower growing genotypes. Tree GE increased with relative growth rate (RGR), and mean GE in Group H was significantly greater than L, but not I. Tree WUEp ranged between 1.7 and 3.9 kg biomass m3 H2O−1, which increased with RGR. At similar levels of Et, WUEp was significantly greater in Group H (2.45 ± 0.20 kg m−3), compared to I (2.03 ± 0.18 kg m−3) or L (1.72 ± 0.23 kg m−3). Leaf and wood Δ13C scaled positively with stem biomass growth but was not correlated with WUEp. However, at a similar biomass increment, clones in Group H and I had significantly lower leaf Δ13C than Group L. Similarly, Group H clones had a significantly lower wood Δ13C than Group L, supporting our hypothesis of increased WUE in larger trees. Tree physiological and hydraulic traits partially explain differences in WUEp and Δ13C, and suggest that clone selection and management activities that increase tree biomass production will likely increase tree and stand WUE. However, more research is needed to discern the underlying hydraulic mechanisms responsible for the higher WUE exhibited by large trees and distinct clones. DA - 2019/11// PY - 2019/11// DO - 10.3390/f10110993 VL - 10 IS - 11 SP - SN - 1999-4907 KW - poplar (Populus) KW - hybrid KW - water-use efficiency KW - sap flow KW - productivity KW - carbon isotope discrimination KW - stomatal conductance ER - TY - BOOK TI - Solid State Fermentation: Research and Industrial Applications AU - Werner, Anett AU - Steudler, Susanne AU - Cheng, Jay AB - This book offers an authoritative review of the main challenges, processes, products and applications of solid state fermentation. They range from enzyme production to the production of antibiotics and pigments to the use in environmental technology and energy production. DA - 2019/// PY - 2019/// DO - 10.1007/978-3-030-23675-5 VL - 169 SE - 1-172 SN - 978-3-030-23674-8 ER - TY - JOUR TI - Terminal voltage analysis for the transformerless PV inverter topologies in a single-phase system AU - Sonti, Venu AU - Jain, Sachin AU - Agarwal, Vivek AU - Bhattacharya, Subhashish T2 - IET RENEWABLE POWER GENERATION AB - This study presents an analysis of the terminal voltage of the basic photovoltaic (PV) inverter topologies available in the literature. The presented analysis utilises the switching function concept. Use of switching function in the analysis enables the inclusion of the effect of the pulse-width modulation technique or the switching strategy on the terminal voltage of the reviewed configuration. It gives insight into the switching action effects on the terminal voltage and provides every detail of the high-frequency transitions in the terminal voltage for the given switching strategy. Using the terminal voltage expression derived in terms of switching function, the analytical waveforms are obtained for various configurations. These waveforms are compared with the simulation and experimental results waveforms to justify the analysis given. This study also presents a bar chart view of the switching and conduction losses of the switches in the reviewed PV inverter topologies. The magnitude of high-frequency components in the terminal voltage and the leakage current is also presented in this study. The PV inverter topologies are also compared in terms of other aspects such as a number of devices used, asymmetry in operation, filter requirement etc. DA - 2019/11/18/ PY - 2019/11/18/ DO - 10.1049/iet-rpg.2019.0106 VL - 13 IS - 15 SP - 2723-2739 SN - 1752-1424 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85075801817&partnerID=MN8TOARS KW - photovoltaic power systems KW - PWM invertors KW - leakage currents KW - conduction losses KW - terminal voltage analysis KW - transformerless PV inverter topologies KW - switching function concept KW - PV inverter topologies KW - single-phase system KW - photovoltaic inverter topologies KW - pulse-width modulation technique KW - high-frequency transitions KW - leakage current ER - TY - JOUR TI - Confined Interlayer Water Promotes Structural Stability for High-Rate Electrochemical Proton Intercalation in Tungsten Oxide Hydrates AU - Mitchell, James B. AU - Geise, Natalie R. AU - Paterson, Alisa R. AU - Osti, Naresh C. AU - Sun, Yangyunli AU - Fleischmann, Simon AU - Zhang, Rui AU - Madsen, Louis A. AU - Toney, Michael F. AU - Jiang, De-en AU - Kolesnikov, Alexander I. AU - Mamontov, Eugene AU - Augustyn, Veronica T2 - ACS Energy Letters AB - There is widespread interest in determining the structural features of redox-active electrochemical energy storage materials that enable simultaneous high power and high energy density. Here, we present the discovery that confined interlayer water in crystalline tungsten oxide hydrates, WO3·nH2O, enables highly reversible proton intercalation at subsecond time scales. By comparing the structural transformation kinetics and confined water dynamics of the hydrates with anhydrous WO3, we determine that the rapid electrochemical proton intercalation is due to the ability of the confined water layers to isolate structural transformations to two dimensions while stabilizing the structure along the third dimension. As a result, these water layers provide both structural flexibility and stability to accommodate intercalation-driven bonding changes. This provides an alternative explanation for the fast energy storage kinetics of materials that incorporate structural water and provides a new strategy for enabling high power and high energy density with redox-active layered materials containing confined fluids. DA - 2019/11// PY - 2019/11// DO - 10.1021/acsenergylett.9b02040 SP - 2805-2812 J2 - ACS Energy Lett. LA - en OP - SN - 2380-8195 2380-8195 UR - http://dx.doi.org/10.1021/acsenergylett.9b02040 DB - Crossref ER - TY - JOUR TI - Complete spatial model calibration AU - Huang, Yen-Ning AU - Reich, Brian J. AU - Fuentes, Montserrat AU - Sankarasubramanian, A. T2 - The Annals of Applied Statistics AB - Computer simulation models are central to environmental science. These mathematical models are used to understand complex weather and climate patterns and to predict the climate’s response to different forcings. Climate models are of course not perfect reflections of reality, and so comparison with observed data is needed to quantify and to correct for biases and other deficiencies. We propose a new method to calibrate model output using observed data. Our approach not only matches the marginal distributions of the model output and gridded observed data, but it simultaneously postprocesses the model output to have the same spatial correlation as the observed data. This comprehensive calibration method permits realistic spatial simulations for regional impact studies. We apply the proposed method to global climate model output in North America and show that it successfully calibrates the model output for temperature and precipitation. DA - 2019/6// PY - 2019/6// DO - 10.1214/18-aoas1219 VL - 13 IS - 2 SP - 746-766 J2 - Ann. Appl. Stat. LA - en OP - SN - 1932-6157 UR - http://dx.doi.org/10.1214/18-aoas1219 DB - Crossref KW - Bayesian methods KW - calibration KW - spatial statistics ER - TY - JOUR TI - Limitations of univariate linear bias correction in yielding cross‐correlation between monthly precipitation and temperature AU - Bhowmik, R. Das AU - Sankarasubramanian, A. T2 - International Journal of Climatology AB - Abstract Statistical bias correction techniques are commonly used in climate model projections to reduce systematic biases. Among the several bias correction techniques, univariate linear bias correction (e.g., quantile mapping) is the most popular, given its simplicity. Univariate linear bias correction can accurately reproduce the observed mean of a given climate variable. However, when performed separately on multiple variables, it does not yield the observed multivariate cross‐correlation structure. In the current study, we consider the intrinsic properties of two candidate univariate linear bias‐correction approaches (simple linear regression and asynchronous regression) in estimating the observed cross‐correlation between precipitation and temperature. Two linear regression models are applied separately on both the observed and the projected variables. The analytical solution suggests that two candidate approaches simply reproduce the cross‐correlation from the general circulation models (GCMs) in the bias‐corrected data set because of their linearity. Our study adopts two frameworks, based on the Fisher z ‐transformation and bootstrapping, to provide 95% lower and upper confidence limits (referred as the permissible bound) for the GCM cross‐correlation. Beyond the permissible bound, raw/bias‐corrected GCM cross‐correlation significantly differs from those observed. Two frameworks are applied on three GCMs from the CMIP5 multimodel ensemble over the coterminous United States. We found that (a) the univariate linear techniques fail to reproduce the observed cross‐correlation in the bias‐corrected data set over 90% (30–50%) of the grid points where the multivariate skewness coefficient values are substantial (small) and statistically significant (statistically insignificant) from zero; (b) the performance of the univariate linear techniques under bootstrapping (Fisher z ‐transformation) remains uniform (non‐uniform) across climate regions, months, and GCMs; (c) grid points, where the observed cross‐correlation is statistically significant, witness a failure fraction of around 0.2 (0.8) under the Fisher z ‐transformation (bootstrapping). The importance of reproducing cross‐correlations is also discussed along with an enquiry into the multivariate approaches that can potentially address the bias in yielding cross‐correlations. DA - 2019/4/16/ PY - 2019/4/16/ DO - 10.1002/joc.6086 VL - 39 IS - 11 SP - 4479-4496 J2 - Int J Climatol LA - en OP - SN - 0899-8418 1097-0088 UR - http://dx.doi.org/10.1002/joc.6086 DB - Crossref KW - bias correction KW - bootstrapping KW - cross-correlation KW - Fisher z-transformation KW - precipitation KW - temperature KW - univariate ER - TY - JOUR TI - Nitrogen Gas Fixation and Conversion to Ammonium Using Microbial Electrolysis Cells AU - Ortiz-Medina, Juan F. AU - Grunden, Amy M. AU - Hyman, Michael R. AU - Call, Douglas F. T2 - ACS Sustainable Chemistry & Engineering AB - Ammonia (NH3) is an important industrial chemical that is produced using the energy- and carbon-intensive Haber-Bosch process. Recovering NH3 from microorganisms that fix nitrogen gas (N2) may provide a sustainable alternative because their specialized nitrogenase enzymes can reduce N2 to ammonium (NH4+) without the need for high temperature and pressure. This study explored the possibility of converting N2 into NH4+ using anaerobic, single-chamber microbial electrolysis cells (MECs). N2 fixation rates [based on an acetylene gas (C2H2) to ethylene gas (C2H4) conversion assay] of a microbial consortium increased significantly when the applied voltage between the anode and cathode increased from 0.7 to 1.0 V and reached a maximum of ∼40 nmol of C2H4 min–1 mg protein–1, which is comparable to model aerobic N2-fixing bacteria. The presence of NH4+, which can inhibit the activity of the nitrogenase enzyme, did not significantly reduce N2 fixation rates. Upon addition of methionine sulfoximine, an NH4+ uptake inhibitor, NH4+ was recovered at rates approaching 5.2 × 10–12 mol of NH4+ s–1 cm–2 (normalized to the anode surface area). Relative to the electrical energy consumed, the normalized energy demand [MJ mol–1 (NH4+)] was negative because of the energy-rich methane gas recovered in the MEC. Including the substrate energy resulted in total energy demands as low as 24 MJ mol–1. Community analysis results of the anode biofilms revealed that Geobacter species predominated in both the presence and absence of NH4+, suggesting that they played a key role in current generation and N2 fixation. This study shows that MECs may provide a new route for generating NH4+. DA - 2019/1// PY - 2019/1// DO - 10.1021/acssuschemeng.8b05763 VL - 7 IS - 3 SP - 3511-3519 J2 - ACS Sustainable Chem. Eng. LA - en OP - SN - 2168-0485 2168-0485 UR - http://dx.doi.org/10.1021/acssuschemeng.8b05763 DB - Crossref KW - Nitrogen fixation KW - Ammonium production KW - Haber-Bosch KW - Microbial electrochemical technology KW - Geobacter ER - TY - JOUR TI - Metamodels to assess the thermal performance of naturally ventilated, low-cost houses in Brazil AU - Rossi, Michele Marta AU - Oliveira Favretto, Ana Paula AU - Grassi, Camila AU - DeCarolis, Joseph AU - Cho, Soolyeon AU - Hill, David AU - Soares Chvatal, Karin Maria AU - Ranjithan, Ranji T2 - ENERGY AND BUILDINGS AB - Building performance simulation [BPS] tools are important in all design stages. However, barriers such as time, resources, and expertise inhibit their use in the early design stages. This study aims to develop, as part of decision-support framework, metamodels to assess the thermal discomfort in a naturally ventilated Brazilian low-cost house during early design. The metamodels predict the degree-hours of discomfort by heat and/or by cold as a function of design parameters for three Brazilian cities: Curitiba, São Paulo, and Manaus. The key design parameters, related with passive design strategies, are building orientation, shading devices position and dimensions, thermal properties of the walls and roof, window-to-wall ratio, and effective window ventilation area. The method consists of three main stages: (i) baseline model development; (ii) Monte Carlo simulation; (iii) multivariate regression. Overall, the metamodels showed R2 values higher than 0.95 for all climates, except the ones predicting discomfort by heat for Curitiba (R2 =0.61) and São Paulo (R2 =0.75). The proposed metamodels can quickly and accurately assess the thermal performance of naturally ventilated low-cost houses. They can be used to guide professionals during the early design stages, and for educational purposes in building design pedagogy. DA - 2019/12/1/ PY - 2019/12/1/ DO - 10.1016/j.enbuild.2019.109457 VL - 204 SP - SN - 1872-6178 KW - Passive design KW - Natural ventilation KW - Metamodel KW - Multivariate regression KW - Early design ER - TY - JOUR TI - Assessing Residents’ Place Attachment to the Guatemalan Maya Landscape Through Mixed Methods Photo Elicitation AU - Peroff, Deidre M. AU - Morais, Duarte B. AU - Seekamp, Erin AU - Sills, Erin AU - Wallace, Tim T2 - Journal of Mixed Methods Research AB - We developed mixed methods photo elicitation to mitigate cultural and language barriers and to acquire deeper understandings of indigenous participants’ place attachment. We define mixed methods photo elicitation to integrate quantitative rankings of photos with qualitative induction of the meanings ascribed to the photos. Multidimensional scaling is used to thematically analyze the resulting photo clusters in relation to qualitative investigation of photo meanings. We also introduce a novel approach to a mixed methods joint display, which was used to visualize emerging themes and reveal how quantitative and qualitative findings are integrated. Reacting to a collection of landscape photographs endemic to rural Guatemala, indigenous farmers expressed place dependence to landscapes for economic and noneconomic reasons, and place identity for sociocultural reasons. DA - 2019/5/15/ PY - 2019/5/15/ DO - 10.1177/1558689819845800 VL - 5 SP - 155868981984580 J2 - Journal of Mixed Methods Research LA - en OP - SN - 1558-6898 1558-6901 UR - http://dx.doi.org/10.1177/1558689819845800 DB - Crossref KW - place identity KW - place dependency KW - Central America KW - tourism microentrepreneurship KW - land stewardship ER - TY - JOUR TI - The Brazilian Forest Code and riparian preservation areas: spatiotemporal analysis and implications for hydrological ecosystem services AU - Biggs, Trent W. AU - Santiago, Thais Muniz Ottoni AU - Sills, Erin AU - Caviglia-Harris, Jill T2 - Regional Environmental Change DA - 2019/8/30/ PY - 2019/8/30/ DO - 10.1007/s10113-019-01549-w VL - 8 J2 - Reg Environ Change LA - en OP - SN - 1436-3798 1436-378X UR - http://dx.doi.org/10.1007/s10113-019-01549-w DB - Crossref KW - Tropical forest KW - Deforestation KW - Riparian zones KW - Hydrological ecosystem services KW - Forest policy KW - Amazon ER - TY - JOUR TI - Intensified Ethylene Production via Chemical Looping through an Exergetically Efficient Redox Scheme AU - Neal, Luke M. AU - Haribal, Vasudev Pralhad AU - Li, Fanxing T2 - ISCIENCE AB - Ethylene production via steam cracking of ethane and naphtha is one of the most energy and emission-intensive processes in the chemical industry. High operating temperatures, significant reaction endothermicity, and complex separations create hefty energy demands and result in substantial CO2 and NOx emissions. Meanwhile, decades of optimization have led to a thermally efficient, near-"perfect" process with ∼95% first law energy efficiency, leaving little room for further reduction in energy consumption and CO2 emissions. In this study, we demonstrate a transformational chemical looping-oxidative dehydrogenation (CL-ODH) process that offers 60%-87% emission reduction through exergy optimization. Through detailed exergy analyses, we show that CL-ODH leads to exergy savings of up to 58% in the upstream reactors and 26% in downstream separations. The feasibility of CL-ODH is supported by a robust redox catalyst that demonstrates stable activity and selectivity for over 1,400 redox cycles in a laboratory-scale fluidized bed reactor. DA - 2019/9/27/ PY - 2019/9/27/ DO - 10.1016/j.isci.2019.08.039 VL - 19 SP - 894-+ SN - 2589-0042 UR - https://doi.org/10.1016/j.isci.2019.08.039 ER - TY - JOUR TI - Design optimization of building geometry and fenestration for daylighting and energy performance AU - Fang, Yuan AU - Cho, Soolyeon T2 - SOLAR ENERGY AB - With the increasing demand for sustainable design and green buildings, building performance is having a greater influence on design decisions. Design decisions on building envelop, especially on building geometry, window and skylight size and placement are essential in the early design stage. This research proposes a building performance optimization process that can help designers simultaneously evaluate the daylighting and energy performance of numerous design options and generate optimized design. The proposed method utilizes parametric design, building simulation modeling, and genetic algorithms. A case study of a small office building is conducted to test and verify the effectiveness of the optimization process. The geometry of the case study building is optimized in three different climates, Miami, Atlanta, and Chicago. After the optimization, the daylighting performance metric UDI is increased by 38.7%, 31.6%, and 28.8%, and the energy performance metric EUI is decreased by 20.2%, 18.5%, and 17.9% compared to average performance values. Sensitivity analysis is performed to analyze the relationship between design variables and performance metrics. The skylight width and length are the most important variables for all locations, while the influence of the other variables varies greatly. DA - 2019/10// PY - 2019/10// DO - 10.1016/j.solener.2019.08.039 VL - 191 SP - 7-18 ER - TY - JOUR TI - Integrating wind, photovoltaic, and large hydropower during the reservoir refilling period AU - Wang, Xianxun AU - Virguez, Edgar AU - Kern, Jordan AU - Chen, Lihua AU - Mei, Yadong AU - Patino-Echeverri, Dalia AU - Wang, Hao T2 - ENERGY CONVERSION AND MANAGEMENT AB - Hydropower facilities are an ideal solution to complement the intermittent production of energy from wind and solar photovoltaic facilities in electric power systems. However, adding this task to the multiple diverse duties of a reservoir (e.g., flood mitigation, water supply, and power generation) poses a challenge related to pursuing multiple and sometimes conflicting objectives. This study proposes an approach for integrating hydro, wind, and photovoltaic power during a reservoir’s refill period. Specifically, this approach simultaneously minimizes the fluctuation in the combined power output of these three resources and maximizes their combined power generation while adhering to the target reservoir’s water levels. The proposed approach uses a multiobjective optimization model that prescribes a day-ahead optimal hourly operation for a hydropower facility in terms of spilled water, water stored in the reservoir, and water used for power generation, while meeting a daily target to refill the reservoir. The prescribed scheduling is then used as the input into a model that simulates the actual operations of the power system. This study focuses on a hydro-wind-photovoltaic system located in southwestern China, where the peak power generating capacity of the hydropower facility is ten percent larger than the combined installed capacity of the wind and solar power. The results show that by using the proposed model, the hydropower facility effectively smooths the fluctuations in the combined power output caused by variable wind and photovoltaic power and concurrently meets the reservoir replenishing targets under dry, moderate, or wet hydrologic scenarios. Furthermore, the trade-offs between power generation maximization and power fluctuation reduction were found to depend on two conditions: whether the reservoir is full, and whether the turbine is generating electricity at its maximum capacity. The hydro-wind-photovoltaic integration is more cost-effective when the reservoir is not full and the turbines are not generating electricity at their maximum capacity. When the reservoir is full, hydropower still has the ability to balance the wind and photovoltaic power without curtailment but tends to result in water spillage (22–402 m3/s) and reductions in electricity generation (0.1–11.4 GWh per day). The proposed method for scheduling operations allows hydropower facilities to complement wind and photovoltaic power output, while meeting the target water levels during the refill period. DA - 2019/10/15/ PY - 2019/10/15/ DO - 10.1016/j.enconman.2019.111778 VL - 198 SP - SN - 1879-2227 KW - Renewable energy KW - Integration KW - Refill operation KW - Multiobjective optimization KW - Pareto frontier KW - Complementary mechanism ER - TY - JOUR TI - Ecosystem services of poplar at long‐term phytoremediation sites in the Midwest and Southeast, United States AU - Zalesny, Ronald S. AU - Headlee, William L. AU - Gopalakrishnan, Gayathri AU - Bauer, Edmund O. AU - Hall, Richard B. AU - Hazel, Dennis W. AU - Isebrands, Jud G. AU - Licht, Louis A. AU - Negri, M. Cristina AU - Nichols, Elizabeth Guthrie AU - Rockwood, Donald L. AU - Wiese, Adam H. T2 - Wiley Interdisciplinary Reviews: Energy and Environment AB - Abstract Short rotation woody crops (SRWCs) including Populus species and their hybrids (i.e., poplars) are ideal for incorporating biomass production with phytotechnologies such as phytoremediation. To integrate these applications, 15 poplar plantings from nine long‐term phytoremediation installations were sampled from 2012 to 2013 in the Midwest (Illinois, Iowa, Wisconsin) and Southeast (Alabama, Florida, North Carolina) United States. In this review, we report summary results of this sampling and how performance at each site compared with comparable phytoremediation systems in the literature. We review significant genotypic differences from each planting within the context of provisioning (i.e., biomass production) and regulating (i.e., carbon sequestration) ecosystem services and how they relate to the need for a cleaner environment during times of accelerated ecological degradation. Overall, the contaminated poplar sites provided these ecosystem services comparable to noncontaminated poplar sites used for bioenergy and biofuels feedstock production. For example, phytoremediation trees at the Midwestern sites had biomass values ranging from 4.4 to 15.5 Mg ha −1 y −1 , which was ~20% less relative to bioenergy trees ( p = .0938). Results were similar for diameter and carbon, with some genotype × environment interactions resulting in phytoremediation trees exhibiting substantially greater growth and productivity (i.e., +131% at one site). As illustrated in the current review, phytoremediation success can be increased with the identification and deployment of genotypes tailored to grow well and tolerate a broad diversity of contaminants (generalists) (i.e., ‘DN34’, ‘NM6’, ‘7300501’) versus those that significantly outperform their counterparts under unique site conditions (specialists) (i.e., ‘220‐5’, ‘51‐5’, ‘S13C20’). This article is categorized under: Concentrating Solar Power > Climate and Environment Bioenergy > Economics and Policy Bioenergy > Science and Materials DA - 2019/6/18/ PY - 2019/6/18/ DO - 10.1002/wene.349 VL - 8 IS - 6 SP - J2 - WIREs Energy Environ. LA - en OP - SN - 2041-8396 2041-840X UR - http://dx.doi.org/10.1002/wene.349 DB - Crossref KW - biomass production KW - carbon sequestration KW - phytotechnologies KW - Populus KW - short rotation woody crops ER - TY - JOUR TI - Aerodynamic Sails for Passive Guidance of High-Altitude Balloons: Static-Stability and Equilibrium Performance AU - Waghela, R. AU - Yoder, C. D. AU - Gopalarathnam, A. AU - Mazzoleni, A. P. T2 - JOURNAL OF AIRCRAFT AB - Balloon trajectory control remains a sought-after goal for the current scientific ballooning community. In this work, a trajectory control system capable of passively guiding a high-altitude balloo... DA - 2019/// PY - 2019/// DO - 10.2514/1.C035353 VL - 56 IS - 5 SP - 1849-1857 SN - 1533-3868 ER - TY - JOUR TI - Dual-Actuator Disc Theory for Turbines in Yaw AU - Khatri, Dheepak N. AU - Chatterjee, Punnag AU - Metoyer, Rodney AU - Mazzoleni, Andre P. AU - Bryant, Matthew AU - Granlund, Kenneth O. T2 - AIAA JOURNAL AB - No AccessTechnical NotesDual-Actuator Disc Theory for Turbines in YawDheepak N. Khatri, Punnag Chatterjee, Rodney Metoyer, Andre P. Mazzoleni, Matthew Bryant and Kenneth O. GranlundDheepak N. KhatriNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Punnag ChatterjeeNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Rodney MetoyerNorth Carolina State University, Raleigh, North Carolina 27695*Graduate Research Assistant, Department of Mechanical and Aerospace Engineering.Search for more papers by this author, Andre P. MazzoleniNorth Carolina State University, Raleigh, North Carolina 27695†Associate Professor, Department of Mechanical and Aerospace Engineering. Associate Fellow AIAA.Search for more papers by this author, Matthew BryantNorth Carolina State University, Raleigh, North Carolina 27695‡Assistant Professor, Department of Mechanical and Aerospace Engineering.Search for more papers by this author and Kenneth O. GranlundNorth Carolina State University, Raleigh, North Carolina 27695§Assistant Professor, Department of Mechanical and Aerospace Engineering. Senior Member AIAA.Search for more papers by this authorPublished Online:23 Jan 2019https://doi.org/10.2514/1.J057740SectionsRead Now ToolsAdd to favoritesDownload citationTrack citations ShareShare onFacebookTwitterLinked InRedditEmail About References [1] Betz A., “Das Maximum der theoretisch möglichen Ausnützung des Windes durch Windmotoren,” Zeitschrift für das gesamte Turbinenwesen, 1920, pp. 26, 307–309. Google Scholar[2] Newman B. G., “Actuator Disc Theory for Vertical Wind Turbines,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 15, Nos. 1–3, 1983, pp. 347–355. doi:https://doi.org/10.1016/0167-6105(83)90204-0 JWEAD6 0167-6105 CrossrefGoogle Scholar[3] Rosenberg A., Selvaraj S. and Sharma A., “A Novel Dual-Rotor Turbine for Increased Wind Energy Capture,” Journal of Physics: Conference Series, Vol. 524, 2014, Paper 012078. doi:https://doi.org/10.1088/1742-6596/524/1/012078 JPCSDZ 1742-6588 CrossrefGoogle Scholar[4] Adams Z. and Chen J., “Flux-Line Theory: A Novel Analytical Model for Cycloturbines,” AIAA Journal, Vol. 55, No. 11, 2017, pp. 3851–3867. doi:https://doi.org/10.2514/1.J055804 AIAJAH 0001-1452 LinkGoogle Scholar[5] Anderson M., “Horizontal Axis Wind Turbines in Yaw,” Proceedings of the First British Wind Energy Association (BWEA) Wind Energy Workshop, 1979, pp. 57–67, http://adsabs.harvard.edu/abs/1979wien.work...57A. Google Scholar[6] Grant I., Parkin P. and Wang X., “Optical Vortex Tracking Studies of a Horizontal Axis Wind Turbine in Yaw Using Laser-Sheet, Flow Visualization,” Experiments in Fluids, Vol. 23, No. 6, 1997, pp. 513–519. doi:https://doi.org/10.1007/s003480050142 EXFLDU 0723-4864 CrossrefGoogle Scholar[7] Newman B. G., “Multiple Actuator Disc Theory for Wind Turbines,” Journal of Wind Engineering and Industrial Aerodynamics, Vol. 24, No. 3, 1986, pp. 215–225. doi:https://doi.org/10.1016/0167-6105(86)90023-1 JWEAD6 0167-6105 CrossrefGoogle Scholar[8] Howland M., Bossuyt J., Martinez-Tossas L., Meyers J. and Meneveau C., “Wake Structure in Actuator Disk Models of Wind Turbines in Yaw Under Uniform Inflow Conditions,” Journal of Renewable and Sustainable Energy, Vol. 8, No. 4, 2016, Paper 043301. doi:https://doi.org/10.1063/1.4955091 CrossrefGoogle Scholar Previous article Next article FiguresReferencesRelatedDetailsCited byPool-Based Tow System for Testing Tethered Hydrokinetic Devices Being Developed to Harvest Energy From Ocean CurrentsMarine Technology Society Journal, Vol. 57, No. 1Blade element momentum theory for a skewed coaxial turbineOcean Engineering, Vol. 269Closed-Loop-Flight-Based Combined Geometric and Structural Wing Design optimization Framework for a Marine Hydrokinetic Energy KiteDemonstration of a Towed Coaxial Turbine Subscale Prototype for Hydrokinetic Energy Harvesting in SkewCharacterization of the Steady-State Operating Conditions of Tethered Coaxial TurbinesIncreased Energy Conversion with a Horizontal Axis Turbine in TranslationModeling, simulation, and equilibrium analysis of tethered coaxial dual-rotor ocean current turbinesEnergy Conversion and Management, Vol. 243Experimental analysis of dual coaxial turbines in skewOcean Engineering, Vol. 215 What's Popular Volume 57, Number 5May 2019 CrossmarkInformationCopyright © 2018 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the eISSN 1533-385X to initiate your request. See also AIAA Rights and Permissions www.aiaa.org/randp. TopicsAerodynamicsAeronautical EngineeringAeronauticsConservation of Momentum EquationsEnergyEnergy FormsEnergy Forms, Production and ConversionEquations of Fluid DynamicsFlow RegimesFluid DynamicsFluid Flow PropertiesTurbinesTurbomachineryWind EngineeringWind Turbine KeywordsTurbinesYawConservation of MassHorizontal Axis TurbineFree Stream VelocityConservation EquationsTwo Dimensional FlowNavier Stokes EquationsKinetic EnergyFluid DensityAcknowledgmentsThis work was funded by a grant from the North Carolina Coastal Studies Institute. The authors would like to thank undergraduate research assistants Tyler Farr and Kyle Weiner for their contributions to these results.PDF Received27 August 2018Accepted2 December 2018Published online23 January 2019 DA - 2019/5// PY - 2019/5// DO - 10.2514/1.J057740 VL - 57 IS - 5 SP - 2204-2208 SN - 1533-385X ER - TY - JOUR TI - Modeling and dynamic analysis of a mobile underwater turbine system for harvesting Marine Hydrokinetic Energy AU - Tandon, Shubham AU - Divi, Sathvik AU - Muglia, Michael AU - Vermillion, Christopher AU - Mazzoleni, Andre T2 - OCEAN ENGINEERING AB - We present the modeling and dynamic analysis of a Mobile Underwater Turbine System, a novel integration of Autonomous Underwater Vehicles and Hydrokinetic Turbines, for harvesting Marine Hydrokinetic Energy from the Gulf Stream. The Gulf Stream, an ocean current that flows off the coast of North Carolina, is a source of hydrokinetic energy. However, the meandering nature of the Gulf Stream makes it challenging to harvest the full energy potential of the stream using fixed turbine systems. One possible solution for increasing the amount of energy that can be extracted from the Gulf Stream involves using a mobile underwater energy harvester system that can follow the meandering stream so as to remain in regions of maximum energy potential. The framework for the conceptual design, and studies focusing on the feasibility of such a system, have been presented previously in (Divi, 2017). The focus of this paper is a mathematical model of the system which has been developed to analyze the dynamics of such a system, along with parametric studies utilizing this model to come up with a system with an optimized set of design parameters. A 6-DOF analytical model of the system is developed to gain an understanding of the system's dynamic behavior and stability. A bead-based tether model is further developed to analyze the behavior of the system when it is anchored and harvesting energy. A study regarding the effects of tether parameters such as the number of tether elements, the spring constant, and the damping coefficient of the tether on the tether behavior and computation time required for analysis, is put forth to help determine an optimal set of tether parameters. In addition, a set of system parameters such as turbine diameter, hull diameter, L/D ratio of the hull and ballast tank size, are analyzed to see how they affect the net energy produced and the maximum distance travelled by the system. Finally, three modes of power transfer to the shore are considered, and an optimization algorithm is presented and used to find the best set of parameters suited for maximum energy transfer for each mode. DA - 2019/9/1/ PY - 2019/9/1/ DO - 10.1016/j.oceaneng.2019.05.051 VL - 187 SP - SN - 0029-8018 KW - Relocatable energy harvester KW - Autonomous underwater vehicle KW - Renewable energy KW - Hydrokinetic energy KW - Ocean current energy KW - Tether modeling ER - TY - JOUR TI - Modified Ceria for "Low-Temperature" CO2 Utilization: A Chemical Looping Route to Exploit Industrial Waste Heat AU - Haribal, Vasudev Pralhad AU - Wang, Xijun AU - Dudek, Ryan AU - Paulus, Courtney AU - Turk, Brian AU - Gupta, Raghubir AU - Li, Fanxing T2 - ADVANCED ENERGY MATERIALS AB - Abstract Efficient CO 2 utilization is key to limit global climate change. Carbon monoxide, which is a crucial feedstock for chemical synthesis, can be produced by splitting CO 2 . However, existing thermochemical routes are energy intensive requiring high operating temperatures. A hybrid redox process (HRP) involving CO 2 ‐to‐CO conversion using a lattice oxygen‐deprived redox catalyst at relatively low temperatures (<700 °C) is reported. The lattice oxygen of the redox catalyst, restored during CO 2 ‐splitting, is subsequently used to convert methane to syngas. Operated at temperatures significantly lower than a number of industrial waste heat sources, this cyclic redox process allows for efficient waste heat‐utilization to convert CO 2 . To enable the low temperature operation, lanthanum modified ceria (1:1 Ce:La) promoted by rhodium (0.5 wt%) is reported as an effective redox catalyst. Near‐complete CO 2 conversion with a syngas yield of up to 83% at low temperatures is achieved using Rh‐promoted LaCeO 4− x . While La improves low‐temperature bulk redox properties of ceria, Rh considerably enhances the surface catalytic properties for methane activation. Density functional theory calculations further illustrate the underlying functions of La‐substitution. The highly effective redox catalyst and HRP scheme provide a potentially attractive route for chemical production using CO 2 , industrial waste heat, and methane, with appreciably lowered CO 2 emissions. DA - 2019/11// PY - 2019/11// DO - 10.1002/aenm.201901963 VL - 9 IS - 41 SP - SN - 1614-6840 UR - https://doi.org/10.1002/aenm.201901963 KW - chemical looping KW - CO2 utilization KW - redox catalyst KW - reforming KW - syngas ER - TY - JOUR TI - Piecemeal or combined? Assessing greenhouse gas mitigation spillovers in US forest and agriculture policy portfolios AU - Galik, Christopher S. AU - Latta, Gregory S. AU - Gambino, Christopher T2 - CLIMATE POLICY AB - Forest and agricultural sector response to comprehensive climate policy is well represented in the literature. Less analysis has been devoted to piecemeal solutions. We use the Forest and Agriculture Sector Optimization Model with Greenhouse Gases (FASOMGHG) to project the individual and combined effect of three existing U.S. Department of Agriculture programmes with potential to increase greenhouse gas (GHG) mitigation. We find that a combined policy scenario may achieve greater mitigation than individual constituent programmes, suggesting the possibility of complementary spillover effects in some periods. Mitigation varies over time, however, and some periods experience net emissions as markets and management practices respond to initial policy shocks. The regional distribution of GHG mitigation also varies between policy scenario. Differences in the magnitude and imputed cost of mitigation under each scenario, generating negative values for some programmes and time periods, reinforces the need to evaluate portfolio design to cost-effectively achieve near-term GHG mitigation.Key policy insights Increased near-term GHG mitigation in the forest and agriculture sectors in the US may be possible by expanding or refocusing the emphasis of existing programmes.Implementing several such forest and agricultural programmes simultaneously may lead to greater GHG mitigation than when implemented separately, indicating the possibility of positive spillover effects.Programmes targeted to agricultural management may hold outsized potential to achieve near-term GHG mitigation; Policies aimed at influencing land use conversion appear to be more vulnerable to reversion and subject to larger inter-annual swings.The staged implementation of programmes could also be useful, helping to encourage increased mitigation (or the retention of already achieved mitigation) over time as markets re-equilibrate to initial shocks.Though the particular scenarios assessed here are unique to the US, our findings may be applicable to other locations outside the US where land management is influenced by individual market actors and there is competition between forest and agricultural land uses. DA - 2019/11/26/ PY - 2019/11/26/ DO - 10.1080/14693062.2019.1663719 VL - 19 IS - 10 SP - 1270-1283 SN - 1752-7457 UR - https://doi.org/10.1080/14693062.2019.1663719 KW - FASOMGHG KW - Conservation Reserve Program KW - policy portfolio KW - land use change and forestry (LULUCF) KW - agriculture KW - climate change mitigation ER - TY - JOUR TI - Electrochemical and Microbiological Characterization of Bioanode Communities Exhibiting Variable Levels of Startup Activity AU - Ortiz-Medina, Juan F. AU - Call, Douglas F. T2 - FRONTIERS IN ENERGY RESEARCH AB - Microbial electrochemical technologies require the establishment of anode biofilms to generate electrical current. The factors driving bioanode formation and their variability during startup remain unclear, leading to a lack of effective strategies to initiate larger-scale systems. Accordingly, our objective was to characterize the electrochemical properties and microbial community structure of a large set of replicate bioanodes during their first cycle of current generation. To do this, we operated eight bioanode replicates at each of two fixed electrode potentials (−0.15 V and +0.15 V vs. standard hydrogen electrode) for one fed-batch cycle. We found that startup time decreased and maximum current generation increased at +0.15 V compared to −0.15 V, but at both potentials the bioanode replicates clustered into three distinct activity levels based on when they initiated current. Despite a large variation in current generation across the eight +0.15 V bioanodes, bioanode resistance and abundance of Geobacter species remained quite similar, differing by only 10% and 12%, respectively. At −0.15 V, current production strongly followed Geobacter species abundance and bioanode resistance, wherein the largest abundance of Geobacter was associated with the lowest charge transfer resistance. Our findings show that startup variability occurs at both applied potentials, but the underlying electrochemical and microbial factors driving variability are dependent on the applied potential. DA - 2019/9/19/ PY - 2019/9/19/ DO - 10.3389/fenrg.2019.00103 VL - 7 SP - SN - 2296-598X KW - microbial electrochemical technologies KW - bioanode KW - Geobacter KW - bioreactor start-up KW - bioenergy ER - TY - JOUR TI - Gate Drivers for High-Frequency Application of Silicon-Carbide MOSFETs AU - Anurag, Anup AU - Acharya, Sayan AU - Bhattacharya, Subhashish T2 - IEEE POWER ELECTRONICS MAGAZINE AB - Design considerations for faster growth of LV and MV applications. This article presented a design overview for SiC gate dtivers as well and their fundamental differences compared to Si gate drivers. Gate drivers for SiC MOSFETs must endure the high dv/dt of switching devices and hence require special considerations. The electrical power path can be separated from the signal path to ensure minimum CM current through the signal path, which guarantees signal fidelity. The design and testing of two LV gate drivers were provided. Certain applications using SiC devices (and correspondingly, SiC gate drivers) were shown. Active gating-based intelligent gate drivers were also widely used, and a concise description for the same was provided. A brief description of designing MV gate drivers (for greater than 3.3 -kV devices) was given. These design considerations can help provide guidelines for building reliable gate drivers for SiC MOSFETs, which in turn can enable faster growth of SiC MOSFETs in both LV and MV applications. DA - 2019/9// PY - 2019/9// DO - 10.1109/MPEL.2019.2925238 VL - 6 IS - 3 SP - 18-31 SN - 2329-9215 UR - https://doi.org/10.1109/MPEL.2019.2925238 ER - TY - JOUR TI - Recent Advances in Intensified Ethylene Production-A Review AU - Gao, Yunfei AU - Neal, Luke AU - Ding, Dong AU - Wu, Wei AU - Baroi, Chinmoy AU - Gaffney, Anne M. AU - Li, Fanxing T2 - ACS CATALYSIS AB - Steam cracking is a well-established commercial technology for ethylene production. Despite decades of optimization efforts, the process is, nevertheless, highly energy and carbon intensive. This review covers the recent advances in alternative approaches that hold promise in the intensification of ethylene production from hydrocarbon feedstocks ranging from methane to naphtha. Oxidative as well as nonoxidative approaches using conventional, chemical looping, membrane, electrochemical, and plasma-assisted systems are discussed. We note that catalysts, electrocatalysts, and/or redox catalysts play critical roles in the performance of these alternative ethylene production technologies. Meanwhile, the complexity in producing polymer-grade ethylene also requires comprehensive considerations of not only (catalytic) reactions for ethylene formation but also feedstock preparation (e.g., air separation for oxidative conversion) and product separations. Although these alternative technologies have yet to be commercially implemented, a number of oxidative approaches have shown promise for close to order-of-magnitude reduction in energy consumption and CO2 emissions in comparison to steam cracking. Given the substantial progress in these research areas and the significant increase in C1 and C2 supplies resulting from the US shale gas revolution, we are excited by the enormous opportunities and potential impacts in the advancement and eventual implementation of significantly intensified ethylene production technologies. DA - 2019/9// PY - 2019/9// DO - 10.1021/acscatal.9b02922 VL - 9 IS - 9 SP - 8592-8621 SN - 2155-5435 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071911366&partnerID=MN8TOARS KW - ethylene KW - process intensification KW - oxidative coupling of methane KW - oxidative dehydrogenation KW - chemical looping KW - electrochemical ethylene production ER - TY - JOUR TI - The role of energy storage in deep decarbonization of electricity production (vol 10, 3413, 2019) AU - Arbabzadeh, Maryam AU - Sioshansi, Ramteen AU - Johnson, Jeremiah X. AU - Keoleian, Gregory A. T2 - NATURE COMMUNICATIONS AB - An amendment to this paper has been published and can be accessed via a link at the top of the paper. DA - 2019/8/26/ PY - 2019/8/26/ DO - 10.1038/s41467-019-11778-6 VL - 10 SP - SN - 2041-1723 ER - TY - JOUR TI - Approaches to fill data gaps and evaluate process completeness in LCA—perspectives from solid waste management systems AU - Henriksen, Trine AU - Levis, James W. AU - Barlaz, Morton A. AU - Damgaard, Anders T2 - The International Journal of Life Cycle Assessment AB - Large data amounts are required in an LCA, but often, site-specific data are missing and less representative surrogate data must be used to fill data gaps. No standardized rules exist on how to address data gaps and process completeness. We suggest a systematic evaluation of process completeness, identification of data gaps, and application of surrogate values to fill the gaps. The study focus on foreground process data. A solid waste management (SWM) scenario was used to illustrate the suggested method. The expected input and output flows in a waste incineration model were identified based on legislation and expert judgment, after which process completeness scores were calculated and missing flows identified. To illustrate the use of different types of surrogate data to fill data gaps, data gaps were selected for 16 different parameters in five SWM processes. We compared the global warming potential (GWP) from using surrogate data, and from leaving the gap, to identify the data gaps where representative surrogate data should be used. The completeness score for the material inputs to waste incineration was 78%, and the missing flows were auxiliary fuels and precipitation chemicals. The completeness score for air emissions were between 38 and 50% with and without expert judgment. If only greenhouse gases were considered (CO2, CH4, and N2O), the completeness score would be 67%. Applying weighting factors according to the greenhouse gas contribution in the USA gave a completeness score of 94%. The system-wide data gaps, where representative surrogate data should be applied, were the CH4 release from composting; electricity generation efficiency of incineration; recovery efficiencies at a material recovery facility; and composition of the plastic, metal, and paper fractions in the household waste; in these cases, leaving the gap changed the GWP results by > 5%. Completeness evaluation should take into account the relevance and importance of flows; relevance depends on the considered life cycle impact methods and importance depends on the weighting of the different flows. The set of expected flows and evaluation of relevance and importance must be documented in a transparent manner. The choice of surrogate values to fill data gaps depends on the availability of secondary data and on whether the data gap matters, i.e., significantly affects the LCA results. The suggested method can be used to properly document the identification of missing flows and to select and apply surrogate values to fill the data gaps. DA - 2019/2/26/ PY - 2019/2/26/ DO - 10.1007/s11367-019-01592-z VL - 24 IS - 9 SP - 1587-1601 J2 - Int J Life Cycle Assess LA - en OP - SN - 0948-3349 1614-7502 UR - http://dx.doi.org/10.1007/s11367-019-01592-z DB - Crossref KW - Completeness KW - Data gaps KW - Surrogate values KW - Representativeness KW - Waste management KW - LCA ER - TY - JOUR TI - Scale-Up Methodology of a Modular Multilevel Converter for HVdc Applications AU - Alharbi, Mohammed AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - Modular multilevel converters (MMCs) are a realistic alternative to the conventional voltage source converters for medium-voltage (MV) and high-voltage direct current (HVdc) applications. The number of submodules (SMs) per arm of the MMC can be as high as 512 to achieve desired high dc voltage levels required for HVdc with a very low total harmonic distortion (THD) (e.g., <;0.1%) of the MMC ac-side interface voltage. Although the low THD of the MMC output voltage with a high number of SMs is desirable, the MMC control implementation and complexity is also important to be considered for the high number of SMs. The MMC control complexity significantly increases as the number of SMs increases. Redesigning the number of SMs in MMCs also becomes quite difficult and may require significant control upgrade, which in turn also needs additional tests and validations. This paper presents an MMC scale-up control methodology applicable for MV and HVdc applications. The number of SMs can be conveniently increased or reduced without any significant control modifications. The proposed control method and capacitor voltage balancing algorithm are implemented in the real-time digital simulator and MMC support units based on field-programmable gate array boards. The performance of the proposed MMC control method is investigated for a point-to-point MMC-based HVdc system under various operating conditions. DA - 2019/// PY - 2019/// DO - 10.1109/TIA.2019.2925055 VL - 55 IS - 5 SP - 4974-4983 SN - 1939-9367 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85071334447&partnerID=MN8TOARS KW - Capacitor voltage balancing (CVB) KW - control design KW - high-voltage direct current (HVdc) KW - modular multilevel converter (MMC) KW - real-time digital simulator (RTDS) ER - TY - JOUR TI - Mixed iron-manganese oxides as redox catalysts for chemical looping-oxidative dehydrogenation of ethane with tailorable heat of reactions AU - Yusuf, Seif AU - Haribal, Vasudev AU - Jackson, Daniel AU - Neal, Luke AU - Li, Fanxing T2 - APPLIED CATALYSIS B-ENVIRONMENTAL AB - The chemical looping-oxidative dehydrogenation (CL-ODH) of ethane is investigated in this study. In CL-ODH, a redox catalyst donates its lattice oxygen to combust hydrogen formed from ethane dehydrogenation (ODH reactor). The reduced redox catalyst is then transferred to a separate reactor (regenerator), where it is re-oxidized with air. Typically, the ODH step is endothermic, due to the high endothermicity to reduce the redox catalyst. This energy demand is met through sensible heat carried by the redox catalyst from the regenerator, which operates at a higher temperature. This temperature difference between the two reactors leads to exergy losses. We report an Fe-Mn redox catalyst showing tunable exothermic heat of reduction. Promotion with Na2WO4 resulted in high ethylene yields due to the suppression of surface Fe/Mn. ASPEN Plus® simulations indicated that Fe-Mn redox catalysts can lower the temperature difference between the two reactors. This can lead to efficiency improvements for CL-ODH. DA - 2019/11/15/ PY - 2019/11/15/ DO - 10.1016/j.apcatb.2019.117885 VL - 257 SP - SN - 1873-3883 UR - https://doi.org/10.1016/j.apcatb.2019.117885 KW - Oxidative dehydrogenation KW - Chemical looping KW - Ethane KW - Ethylene ER - TY - JOUR TI - Are e-scooters polluters? The environmental impacts of shared dockless electric scooters AU - Hollingsworth, Joseph AU - Copeland, Brenna AU - Johnson, Jeremiah X. T2 - ENVIRONMENTAL RESEARCH LETTERS AB - Abstract Shared stand-up electric scooters are now offered in many cities as an option for short-term rental, and marketed for short-distance travel. Using life cycle assessment, we quantify the total environmental impacts of this mobility option associated with global warming, acidification, eutrophication, and respiratory impacts. We find that environmental burdens associated with charging the e-scooter are small relative to materials and manufacturing burdens of the e-scooters and the impacts associated with transporting the scooters to overnight charging stations. The results of a Monte Carlo analysis show an average value of life cycle global warming impacts of 202 g CO 2 -eq/passenger-mile, driven by materials and manufacturing (50%), followed by daily collection for charging (43% of impact). We illustrate the potential to reduce life cycle global warming impacts through improved scooter collection and charging approaches, including the use of fuel-efficient vehicles for collection (yielding 177 g CO 2 -eq/passenger-mile), limiting scooter collection to those with a low battery state of charge (164 g CO 2 -eq/passenger-mile), and reducing the driving distance per scooter for e-scooter collection and distribution (147 g CO 2 -eq/passenger-mile). The results prove to be highly sensitive to e-scooter lifetime; ensuring that the shared e-scooters are used for two years decreases the average life cycle emissions to 141 g CO 2 -eq/passenger-mile. Under our Base Case assumptions, we find that the life cycle greenhouse gas emissions associated with e-scooter use is higher in 65% of our Monte Carlo simulations than the suite of modes of transportation that are displaced. This likelihood drops to 35%–50% under our improved and efficient e-scooter collection processes and only 4% when we assume two-year e-scooter lifetimes. When e-scooter usage replaces average personal automobile travel, we nearly universally realize a net reduction in environmental impacts. DA - 2019/8// PY - 2019/8// DO - 10.1088/1748-9326/ab2da8 VL - 14 IS - 8 SP - SN - 1748-9326 KW - electric scooter KW - life cycle assessment KW - transportation KW - environmental impacts ER - TY - JOUR TI - Free-standing transition metal oxide electrode architectures for electrochemical energy storage AU - Spencer, Michael A. AU - Augustyn, Veronica T2 - JOURNAL OF MATERIALS SCIENCE DA - 2019/10// PY - 2019/10// DO - 10.1007/s10853-019-03823-y VL - 54 IS - 20 SP - 13045-13069 SN - 1573-4803 ER - TY - JOUR TI - The role of energy storage in deep decarbonization of electricity production AU - Arbabzadeh, Maryam AU - Sioshansi, Ramteen AU - Johnson, Jeremiah X. AU - Keoleian, Gregory A. T2 - NATURE COMMUNICATIONS AB - Abstract Deep decarbonization of electricity production is a societal challenge that can be achieved with high penetrations of variable renewable energy. We investigate the potential of energy storage technologies to reduce renewable curtailment and CO 2 emissions in California and Texas under varying emissions taxes. We show that without energy storage, adding 60 GW of renewables to California achieves 72% CO 2 reductions (relative to a zero-renewables case) with close to one third of renewables being curtailed. Some energy storage technologies, on the other hand, allow 90% CO 2 reductions from the same renewable penetrations with as little as 9% renewable curtailment. In Texas, the same renewable-deployment level leads to 54% emissions reductions with close to 3% renewable curtailment. Energy storage can allow 57% emissions reductions with as little as 0.3% renewable curtailment. We also find that generator flexibility can reduce curtailment and the amount of energy storage that is needed for renewable integration. DA - 2019/7/30/ PY - 2019/7/30/ DO - 10.1038/s41467-019-11161-5 VL - 10 SP - SN - 2041-1723 ER - TY - JOUR TI - Repurposing an energy system optimization model for seasonal power generation planning AU - de Queiroz, A.R. AU - Mulcahy, D. AU - Sankarasubramanian, A. AU - Deane, J.P. AU - Mahinthakumar, G. AU - Lu, N. AU - DeCarolis, J.F. T2 - Energy AB - Seasonal climate variations affect electricity demand, which in turn affects month-to-month electricity planning and operations. Electricity system planning at the monthly timescale can be improved by adapting climate forecasts to estimate electricity demand and utilizing energy models to estimate monthly electricity generation and associated operational costs. The objective of this paper is to develop and test a computationally efficient model that can support seasonal planning while preserving key aspects of system operation over hourly and daily timeframes. To do so, an energy system optimization model is repurposed for seasonal planning using features drawn from a unit commitment model. Different scenarios utilizing a well-known test system are used to evaluate the errors associated with both the repurposed energy system model and an imperfect load forecast. The results show that the energy system optimization model using an imperfect load forecast produces differences in monthly cost and generation levels that are less than 2% compared with a unit commitment model using a perfect load forecast. The enhanced energy system optimization model can be solved approximately 100 times faster than the unit commitment model, making it a suitable tool for future work aimed at evaluating seasonal electricity generation and demand under uncertainty. DA - 2019/8// PY - 2019/8// DO - 10.1016/j.energy.2019.05.126 VL - 181 SP - 1321-1330 J2 - Energy LA - en OP - SN - 0360-5442 UR - http://dx.doi.org/10.1016/j.energy.2019.05.126 DB - Crossref KW - Power generation planning KW - Unit commitment KW - Energy system optimization KW - Seasonal demand forecasts KW - Mathematical programming ER - TY - JOUR TI - A Hybrid 7-Level Inverter Using Low-Voltage Devices and Operation With Single DC-Link AU - Yadav, Apurv Kumar AU - Gopakumar, K. AU - Raj, Krishna R. AU - Umanand, Loganathan AU - Bhattacharya, Subhashish AU - Jarzyna, Wojciech T2 - IEEE TRANSACTIONS ON POWER ELECTRONICS AB - This paper proposes a new 7-level inverter topology for induction motor drives. It is a hybrid topology formed by cascading a 5-level active neutral-point-clamped inverter with a 3-level T-type converter. It is obtained using low-voltage semiconductor devices with voltage blocking capability of Vdc/3 and Vdc/6. The topology uses three floating capacitors per phase, which are balanced within a pulsewidth modulation (PWM) switching duration using switching-state redundancies for each pole-voltage level. Topology forms two stacks at the front-end, which requires individual symmetrical dc source. The analysis of switching loss and conduction loss is performed and compared with some of the existing 7-level multi-level inverters reported in various literatures to show the advantages of the proposed topology. Furthermore, the single dc source operation with two stacked capacitors and closed-loop control of neutral-point voltage using symmetrical six-phase induction motor is proposed. The voltage-control algorithms for floating capacitors and dc-link stacked capacitors are proposed, which are independent of load power factor and modulation index. Open-loop V/f and closed-loop rotor field oriented control are performed, and various results at steady and transient states are presented to validate the aforementioned claims. DA - 2019/10// PY - 2019/10// DO - 10.1109/TPEL.2018.2890371 VL - 34 IS - 10 SP - 9844-9853 SN - 1941-0107 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85068675417&partnerID=MN8TOARS KW - 7-level inverter KW - hybrid multi-level inverter (MLI) KW - induction motor (IM) drive KW - multi-level converter KW - neutral-point voltage (NPV) ER - TY - JOUR TI - A systems and control perspective of CPS security AU - Dibaji, Seyed Mehran AU - Pirani, Mohammad AU - Flamholz, David Bezalel AU - Annaswamy, Anuradha M. AU - Johansson, Karl Henrik AU - Chakrabortty, Aranya T2 - ANNUAL REVIEWS IN CONTROL AB - The comprehensive integration of instrumentation, communication, and control into physical systems has led to the study of Cyber-Physical Systems (CPSs), a field that has recently garnered increased attention. A key concern that is ubiquitous in CPS is a need to ensure security in the face of cyber attacks. In this paper, we carry out a survey of systems and control methods that have been proposed for the security of CPS. We classify these methods into three categories based on the type of defense proposed against the cyberattacks: prevention, resilience, and detection & isolation. A unified threat assessment metric is proposed in order to evaluate how CPS security is achieved in each of these three cases. Also surveyed are the risk assessment tools and the effect of network topology on CPS security. Furthermore, an emphasis has been placed on power and transportation applications in the overall survey. DA - 2019/// PY - 2019/// DO - 10.1016/j.arcontrol.2019.04.011 VL - 47 SP - 394-411 SN - 1367-5788 KW - Cyber-physical systems KW - Cyber-security KW - Cyber-physical security KW - Secure control KW - Resilient control ER - TY - JOUR TI - Microfibers generated from the laundering of cotton, rayon and polyester based fabrics and their aquatic biodegradation AU - Zambrano, Marielis C. AU - Pawlak, Joel J. AU - Daystar, Jesse AU - Ankeny, Mary AU - Cheng, Jay J. AU - Venditti, Richard A. T2 - MARINE POLLUTION BULLETIN AB - The effect of fiber type (cotton, polyester, and rayon), temperature, and use of detergent on the number of microfibers released during laundering of knitted fabrics were studied during accelerated laboratory washing (Launder-Ometer) and home laundering experiments. Polyester and cellulose-based fabrics all shed significant amounts of microfibers and shedding levels were increased with higher water temperature and detergent use. Cellulose-based fabrics released more microfibers (0.2–4 mg/g fabric) during accelerated laundering than polyester (0.1–1 mg/g fabric). Using well-controlled aquatic biodegradation experiments it was shown that cotton and rayon microfibers are expected to degrade in natural aquatic aerobic environments whereas polyester microfibers are expected to persist in the environment for long periods of time. DA - 2019/5// PY - 2019/5// DO - 10.1016/j.marpolbul.2019.02.062 VL - 142 SP - 394-407 SN - 1879-3363 KW - Microplastics KW - Microfibers KW - Laundering KW - Biodegradation KW - Textiles KW - Aquatic environments ER - TY - JOUR TI - Control and Real-Time Validation for Convertible Static Transmission Controller Enabled Dual Active Power Filters and PV Integration AU - Alfaris, Faris E. AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - This paper proposes a versatile convertible static transmission controller, in shunt-shunt mode, with dual active filters and photovoltaic (PV) power integration. The combined system aims to back up and control the power of a transmission transformer, as well as, improve the transmitted power quality to meet the grid standards and codes, especially the recently revised IEEE 1547 standards. The filters are also designed to eliminate the current and voltage harmonics due to the fluctuation in the injected PV power and the use of the switching power converters. A new reference generation technique is proposed to inject the solar power into the grid and compensate the system reactive power and harmonics. Moreover, the varying nature of PV power, due to the intermittent solar radiation and temperature, is accounted with the online computation of the dc voltage and power references with the help of the system rectifier. A simulation study adopted by real-time digital simulator is used to validate the proposed system for the integration of an actual solar PV under normal and faulted conditions. DA - 2019/// PY - 2019/// DO - 10.1109/TIA.2019.2910782 VL - 55 IS - 4 SP - 4309-4320 SN - 1939-9367 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85068899634&partnerID=MN8TOARS KW - Active power filter KW - back-to-back (BTB) HVdc systems KW - dc-link voltage stability KW - flexible ac transmission system KW - photovoltaic (PV) power integration KW - power factor correction ER - TY - JOUR TI - Polycentric Systems and Multiscale Climate Change Mitigation and Adaptation in the Built Environment Palabras clave AU - Ba, Yuhao AU - Galik, Christopher T2 - REVIEW OF POLICY RESEARCH AB - Abstract Addressing climate change requires consideration of mitigation and adaptation opportunities at multiple spatial scales. This is particularly true in the built environment, defined here to include individual buildings, neighborhoods, and the spaces between. The current U.S. political environment portends fewer resources and coordinating services for mitigation and adaptation at the federal level, however, reinforcing the relevance and necessity of actions at subnational levels. In this study, we evaluate the applicability of a polycentric model of governance to the implementation of mitigation and adaptation practices, as well as the presence of polycentric systems in the built environment. We assemble a database of practices with the potential to achieve both mitigation and adaptation objectives, as well as those that may be cross‐purposed or that may achieve one but not the other. We review practices to gauge the applicability of a polycentric model of governance to mitigation and adaptation practices in the built environment, and examine the attributes of three existing adaptation and/or mitigation programs to assess the extent to which they exhibit polycentric attributes. We conclude with recommendations for a broader research agenda, including efforts to develop more in‐depth examinations into individual programs and comparative analysis of performances of different governance attributes. DA - 2019/7// PY - 2019/7// DO - 10.1111/ropr.12342 VL - 36 IS - 4 SP - 473-496 SN - 1541-1338 KW - climate change KW - environment KW - governance KW - regional governance ER - TY - JOUR TI - Evaluation of optimal model parameters for prediction of methane generation from selected US landfills AU - Sun, Wenjie AU - Wang, Xiaoming AU - DeCarolis, Joseph F. AU - Barlaz, Morton A. T2 - WASTE MANAGEMENT AB - In practice, methane generation at U.S. landfills is typically predicted by using the EPA's Landfill Gas Emissions Model (LandGEM), which includes two parameters, the methane production potential (L0, m3 CH4 Mg-1 wet waste) and the first-order decay rate constant (k, yr-1). Default parameters in LandGEM (L0 = 100 and k = 0.04) were determined using data that reflect landfill management practices in the 1990s. In this study, methane collection data from 21 U.S. landfills were used to estimate the best fit k by inverse modeling of measured methane collection data in consideration of a time-varying gas collection efficiency. Optimal values of k were identified at a range of L0s between 55 and 160. The best fit k was greater than the U.S. EPA's default parameter of 0.04 yr-1 at 14 of the 21 landfills studied. Surprisingly, the best fit k was often observed at L0 values greater than 100 m3 CH4 Mg-1 wet waste which again is the U.S. EPA default. The results show that there is wide variation in the best estimate of k. While there was a tendency for landfills, or sections of landfills that received more moisture to exhibit higher decay rates, the results were not consistent. Some landfills exhibited high decay rates even though the data suggested that they were relatively dry while some wet landfills exhibited low decay rates. The results suggest that L0 captures many factors and that the data may be most useful for site specific analysis as opposed to general landfill predictions. DA - 2019/5/15/ PY - 2019/5/15/ DO - 10.1016/j.wasman.2019.05.004 VL - 91 SP - 120-127 SN - 0956-053X KW - Landfills KW - Landfill gas KW - Methane KW - Gas collection efficiency KW - LandGEM ER - TY - JOUR TI - Incentive mechanism for sharing distributed energy resources AU - Wang, Jianxiao AU - Zhong, Haiwang AU - Qin, Junjie AU - Tang, Wenyuan AU - Rajagopal, Ram AU - Xia, Qing AU - Kang, Chongqing T2 - Journal of Modern Power Systems and Clean Energy AB - To improve the controllability and utilization of distributed energy resources (DERs), distribution-level electricity markets based on consumers’ bids and offers have been proposed. However, the transaction costs will dramatically increase with the rapid development of DERs. Therefore, in this paper, we develop an energy sharing scheme that allows users to share DERs with neighbors, and design a novel incentive mechanism for benefit allocation without users’ bidding on electricity prices. In the energy sharing scheme, an aggregator organizes a number of electricity users, and trades with the connected power grid. The aggregator is aimed at minimizing the total costs by matching the surplus energy from DERs and electrical loads. A novel index, termed as sharing contribution rate (SCR), is presented to evaluate different users’ contributions to the energy sharing. Then, based on users’ SCRs, an efficient benefit allocation mechanism is implemented to determine the aggregator’s payments to users that incentivize their participation in energy sharing. To avoid users’ bidding, we propose a decentralized framework for the energy sharing and incentive mechanism. Case studies based on real-world datasets demonstrate that the aggregator and users can benefit from the energy sharing scheme, and the incentive mechanism allocates the benefits according to users’ contributions. DA - 2019/4/5/ PY - 2019/4/5/ DO - 10.1007/s40565-019-0518-5 J2 - J. Mod. Power Syst. Clean Energy LA - en OP - SN - 2196-5625 2196-5420 UR - http://dx.doi.org/10.1007/s40565-019-0518-5 DB - Crossref KW - Distributed energy resource KW - Energy sharing KW - Incentive mechanism KW - Nash bargaining ER - TY - JOUR TI - Finite-Element Analysis Modeling of High-Frequency Single-Phase Transformers Enabled by Metal Amorphous Nanocomposites and Calculation of Leakage Inductance for Different Winding Topologies AU - Nazmunnahar, M. AU - Simizu, S. AU - Ohodnicki, P. R. AU - Bhattacharya, S. AU - McHenry, M. E. T2 - IEEE TRANSACTIONS ON MAGNETICS AB - The solid-state transformer (SST) is an emerging technology which is gaining increasing importance for future power distribution systems. Here, we present 2-D finite-element analysis (FEA) of single-phase SSTs for operating frequencies of 50 kHz. We consider designs to benchmark materials aimed at controlling high-frequency losses to achieve higher power densities. The FEA model is solved in the time domain for frequencies of 50 kHz, at a fixed 800 V input voltage and 10 kW output power for the first four cycles. This paper analyzes the influence of leakage inductance on the waveform with an increasing number of turns and discusses how to calculate the leakage inductance of the different winding topologies by FEA. In addition, transformer topologies are coupled to a power analysis using a Steinmetz parameterization of magnetic losses capturing induction and field scaling for transformer losses for FeNi-based metal amorphous nanocomposites (MANCs) for SST applications and their benchmarking with amorphous and other MANCs and ferrites. Recently, discovered FeNi-based MANCs allow smaller transformers at equivalent power as compared to Si steels, Metglas, and Co-based MANCs. These Fe-rich and non-Co containing MANCs also offer economies based on lower raw materials costs as compared with Co-based MANCs and significantly improved mechanical properties with respect to commercially available Fe-based MANCs. DA - 2019/7// PY - 2019/7// DO - 10.1109/TMAG.2019.2904007 VL - 55 IS - 7 SP - SN - 1941-0069 UR - https://doi.org/10.1109/TMAG.2019.2904007 KW - Finite element analysis (FEA) KW - metal amorphous nanocomposite materials (MANC) KW - solid-state transformer (SST) KW - transformer leakage inductance ER - TY - JOUR TI - Effects of Co-occurring Species Present in Swine Lagoons on Adsorption of Copper on Eggshell AU - Hess, Brianna J. AU - Kolar, Praveen AU - Classen, John J. AU - Knappe, Detlef AU - Cheng, Jay J. T2 - INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH DA - 2019/8// PY - 2019/8// DO - 10.1007/s41742-019-00203-x VL - 13 IS - 4 SP - 613-622 SN - 2008-2304 KW - Adsorption KW - Eggshell KW - Copper KW - Swine lagoons KW - Acetate KW - Ammonia ER - TY - JOUR TI - Modelling and performance analysis of a tether and sail-based trajectory control system for extra-terrestrial scientific balloon missions AU - Yoder, Christopher D. AU - Gemmer, Thomas R. AU - Mazzoleni, Andre P. T2 - ACTA ASTRONAUTICA AB - Balloon systems show great promise for exploring the atmospheres of extra-terrestrial bodies in the solar system. The balloon system concept was demonstrated by the aerostats aboard the Vega 1 and 2 missions sent to Venus. Such systems glean propulsion from atmospheric winds, and at present are unable to travel in a direction perpendicular to the direction of the wind, limiting their exploration potential. A control system capable of modifying the system trajectory by traveling in a direction perpendicular to the direction of the wind is desired to increase exploration potential as well as to perform tasks such as maintaining latitude. A balloon and sail system which can use wind velocity and density gradients to produce a guiding force perpendicular to the velocity of the wind is discussed here. Such a guidance system is passive in nature and requires little power for actuation and control. It was previously demonstrated that such a control system is capable of generating guiding velocities of several meters per second within the Venusian atmosphere. Furthermore, this control system was shown to be capable of achieving sufficient control for the majority of the latitudes on Venus. This work builds on previous results and demonstrates the benefits of being able to generate guiding velocities via a sail system by viewing the trajectories taken by planetary balloon systems employing such a system. First, a description of the system model is given. Next, for the atmospheres of Venus and Titan, trajectory control is demonstrated for various sail parameters, such as sail size and mass. The benefit of such control is shown by the ability to achieve various latitudes of interest for a given flight duration. These latitudes are chosen based on geographic features, such as lakes on Titan. Finally, a PI controller is added to the model to demonstrate rudimentary control of the balloon system for maintaining and changing latitudes. A brief discussion regarding the control law of the system is also provided. DA - 2019/7// PY - 2019/7// DO - 10.1016/j.actaastro.2018.12.030 VL - 160 SP - 527-537 SN - 1879-2030 KW - Balloon KW - Sail KW - Venus KW - Titan KW - Latitude KW - Control ER - TY - JOUR TI - Effect of Air-Conditioning on Light Duty Gasoline Vehicles Fuel Economy AU - Khan, Tanzila AU - Frey, H. Christopher T2 - TRANSPORTATION RESEARCH RECORD AB - With more stringent U.S. fuel economy (FE) standards, the effect of auxiliary devices such as air-conditioning (AC) have received increased attention. AC is the largest auxiliary engine load for light duty gasoline vehicles (LDGVs). However, there are few data regarding the effect of AC operation on FE for LDGVs based on real-world measurements, especially for recent model year vehicles. The Motor Vehicle Emission Simulator (MOVES) is a regulatory model for estimating on-road vehicle energy-use and emissions. MOVES adjusts vehicle energy-use rates for AC effects. However, MOVES-predicted FE with AC has not been evaluated based on empirical measurements. The research objectives are to quantify the LDGVs FE penalty from AC and assess the accuracy of MOVES2014a-predicted FE with AC. The AC effect on real-world fleet-average FE was quantified based on 78 AC-off vehicles versus 55 AC-on vehicles, measured with onboard instruments on defined study routes. MOVES2014a-based FE penalty from AC was evaluated based on real-world estimates and chassis dynamometer-based FE test results used for FE ratings. The real-world FE penalty ranges between 1.3% and 7.5% among a wide range of driving cycles. Fuel consumption at idle is 13% higher with AC on. MOVES underestimates the real-world FE with AC by 6%, on average. MOVES overestimates the AC effect on cycle-average FE ranging between 13.5% and 18.5% for real-world and MOVES default cycles, and between 11.1% and 14.5% for standard cycles. DA - 2019/5// PY - 2019/5// DO - 10.1177/0361198119838507 VL - 2673 IS - 5 SP - 131-141 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85063930471&partnerID=MN8TOARS ER - TY - JOUR TI - Quantification of Energy Saving Potential for A Passenger Train Based on Inter-Run Variability in Speed Trajectories AU - Yuan, Weichang AU - Frey, H. Christopher AU - Rastogi, Nikhil T2 - TRANSPORTATION RESEARCH RECORD AB - Passenger train energy consumption is dependent on speed trajectories. The variability of passenger train energy consumption owing to the variability in speed trajectories can help identify ways to reduce train energy use via improved operations. Empirical fuel use data from a portable measurement emission measurement system (PEMS) and empirical speed trajectories measured using a global positioning system (GPS) receiver were used to verify and quantify real-world energy consumption variability and the variability in empirical speed trajectories, respectively. To identify potential realistic speed trajectories that can lead to energy saving (i.e., eco-driving), a Markov chain based speed trajectory simulator was used to simulate inter-run variability in speed trajectories. An energy index model (EIM) was used to compare energy consumption among different speed trajectories. The results show inter-run variability in fuel use associated with inter-run variability in the empirical speed trajectories. There is also inter-segment variability in fuel use related to the segment length and grade. The Markov chain based speed trajectory simulator can simulate realistic inter-run variability in speed trajectories based on calibration using empirical speed trajectories. The number of empirical speed trajectories used for simulator calibration affects the range of simulated inter-run variability. The EIM provides an accurate estimation of the empirical fuel use. Eco-driving, such as reducing the peak speed, can reduce energy consumption without compromising travel time. The methodology shown in this study is not system-specific and can be applied to other passenger train systems. DA - 2019/5// PY - 2019/5// DO - 10.1177/0361198119838516 VL - 2673 IS - 5 SP - 153-165 SN - 2169-4052 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85063956284&partnerID=MN8TOARS ER - TY - JOUR TI - Deconstructing the policyscape for reducing deforestation in the Eastern Amazon: Practical insights for a landscape approach AU - Gebara, Maria Fernanda AU - Sills, Erin AU - May, Peter AU - Forsyth, Tim T2 - Environmental Policy and Governance AB - Abstract In international debates on climate change mitigation and forests, there is increased recognition of the importance of a landscape approach to effectively address tropical deforestation. Such an approach, although increasingly promoted, remains only loosely defined and requires further development in order to effectively integrate different interventions at landscape level. In particular, it is important to understand the possible interactions between different landscape interventions at local level—where they are intended to have effect—and the challenges associated with them. Inspired by the complexity of policy mix analysis, this article seeks to shed light on these interactions by analysing how different policies and measures for reducing deforestation and degradation have played out in a jurisdiction with wide‐ranging actors and interventions aimed at shaping their behaviour. Focusing on smallholders, we examine the Sustainable Landscapes Pilot Programme in São Félix do Xingu, looking at how different policies interact—categorising interactions as “complementary,” “mutually reinforcing” (synergistic), “in conflict,” “interdependent,” and/or “redundant”—and explain how proponents of this pilot programme seek to integrate them. Most analysis is based on primary data collected through quantitative (i.e., random stratified sampling and surveys) and qualitative (i.e., observation and focus groups) methods. The São Félix do Xingu case shows that understanding effects of different policies and measures on people's behaviour requires a deeper look at local perceptions and reactions to such policies and measures, something most studies on the topic have overlooked. Ultimately, the heterogeneity and complexity of social practices that permeate landscapes must be recognised in order to integrate diverse measures to reduce deforestation. DA - 2019/2/28/ PY - 2019/2/28/ DO - 10.1002/eet.1846 VL - 29 IS - 3 SP - 185-197 J2 - Env Pol Gov LA - en OP - SN - 1756-932X 1756-9338 UR - http://dx.doi.org/10.1002/eet.1846 DB - Crossref KW - behaviour change KW - Brazilian Amazon KW - landscape approach KW - policyscape ER - TY - JOUR TI - Economics of Enhancing Nutrient Circularity in an Organic Waste Valorization System AU - Cobo, Selene AU - Levis, James W. AU - Dominguez-Ramos, Antonio AU - Irabien, Angel T2 - Environmental Science & Technology AB - Waste managers struggle to comply with the European legislation that regulates the handling of organic waste. A waste management system that aims at recovering nutrients from the municipal organic waste generated in the Spanish region of Cantabria was modeled by combining material flow analysis, life cycle assessment, and life cycle costing. The model was optimized to find system configurations that minimize the total annual cost (TAC) and the global warming impacts (GW) and maximize the circularity indicators of nitrogen and phosphorus (CIN and CIP). The developed superstructure is composed of waste management unit processes and unit processes related to the land application of the recovered products (compost, digestate, (NH4)2SO4, and NH4MgPO4·6H2O) and industrial fertilizers to grow corn. The results of the optimization indicate that increasing CIN and minimizing GW raises the TAC, because of the investment in new technologies, although high CIP values can be achieved at low TACs. The economic margin that enables the organic fertilizers to compete in the market with industrial fertilizers was estimated. Cooperation between waste managers, the farmers that purchase the recovered products, and the policy-makers that set the waste management taxes can minimize the costs that hinder the transition toward a circular economy. DA - 2019/5/10/ PY - 2019/5/10/ DO - 10.1021/acs.est.8b06035 VL - 53 IS - 11 SP - 6123-6132 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/acs.est.8b06035 DB - Crossref ER - TY - JOUR TI - Application priority of GSHP systems in the climate conditions of the United States AU - Cho, Soolyeon AU - Ray, Saurabh AU - Im, Piljae AU - Honari, Hamed AU - Ahn, Jonghoon T2 - ADVANCES IN BUILDING ENERGY RESEARCH AB - Building energy-performance simulation programs are powerful tools for many aspects of feasibility studies regarding ground source heat pump (GSHP). However, the understanding of the limitations of the energy modelling programs, their capability of predicting energy performance early in the design process, and the complicated functionality of these programs makes the software programs harder to use and less practical. The interactive tool developed in this study seeks to provide analysis information in a straightforward manner that is inexpensive, convenient, and sophisticated. This tool uses an inclusive approach to assess the feasibility of GSHPs by prescreening critical factors such as climate conditions, ground temperatures, energy use, and cost savings. It is interactive and enables the user to do a feasibility analysis with a weighting factor for each feasibility criterion based on the user’s preference and interests. The application of the tool explains feasibility scores of 15 representative cities in various climatic conditions across the US. Results for commercial buildings show that the GSHP systems are more feasible in cold and dry, cool and humid, and very cold areas than warm and dry, very hot and humid, and mixed marine areas, and that most feasibility levels are located on good and moderate. DA - 2019/// PY - 2019/// DO - 10.1080/17512549.2017.1325403 VL - 13 IS - 1 SP - 1-17 SN - 1756-2201 KW - Feasibility strategy KW - energy use KW - ground source heat pump KW - multi-dimensional analysis KW - residential and commercial buildings KW - integrated feasibility score ER - TY - JOUR TI - Redox oxidative cracking of n-hexane with Fe-substituted barium hexaaluminates as redox catalysts AU - Tian, Xin AU - Dudek, Ryan B. AU - Gao, Yunfei AU - Zhao, Haibo AU - Li, Fanxing T2 - CATALYSIS SCIENCE & TECHNOLOGY AB - Promoted hexaaluminate redox catalysts achieved excellent olefin yield while allowing autothermal redox oxidative cracking of naphtha with low COx formation. DA - 2019/5/7/ PY - 2019/5/7/ DO - 10.1039/c8cy02530d VL - 9 IS - 9 SP - 2211-2220 SN - 2044-4761 UR - https://doi.org/10.1039/C8CY02530D ER - TY - JOUR TI - Online contingency analysis method for multi-terminal DC distribution networks with renewable resources AU - Chen, Pengwei AU - Xiao, Xiangning AU - Baran, Mesut AU - Wang, Xiaochu T2 - IET GENERATION TRANSMISSION & DISTRIBUTION AB - In this study, an interval arithmetic-based method has been proposed for contingency analysis of line outage in DC distribution networks. This method incorporates the uncertainties in source/load which become considerable in the system with increasing renewable generations and time-varying loads. Two-stage contingency analysis approach is adopted in this method. For the first stage of contingency screening, a contingency filter has been developed based on interval matrix norm to quickly estimate the bounds of operating state in the post-outage period. For the second stage of detailed analysis to the selected contingencies, the interval analytical model is first transformed into a non-linear programming-based equivalent model. To solve this model accurately and efficiently, successive linear programming and reformulation-linearisation techniques are employed. The proposed method is benchmarked against Monte Carlo simulations and line outage distribution factor-based method. DA - 2019/4/23/ PY - 2019/4/23/ DO - 10.1049/iet-gtd.2018.5318 VL - 13 IS - 8 SP - 1305-1314 SN - 1751-8695 ER - TY - JOUR TI - Artificial neural network based modeling for the prediction of yield and surface area of activated carbon from biomass AU - Liao, Mochen AU - Kelley, Stephen S AU - Yao, Yuan T2 - Biofuels, Bioproducts and Biorefining AB - Abstract Activated carbon (AC) is an adsorbent material with broad industrial applications. Understanding and predicting the yield and quality of AC produced from different feedstock is critical for biomass screening and process design. In this study, multi‐layer feedforward artificial neural network (ANN) models were developed to predict the total yield and surface area of AC produced from various biomass feedstock using pyrolysis and steam activation. In total, 168 data samples identified from experiments in literature were used to train, validate, and test the ANN models. The trained ANN models showed high accuracy ( R 2 > 0.9) and demonstrated good alignment with the independent experimental data. The impacts of using datasets based on different biomass characterization methods (i.e., ultimate analysis and proximate analysis) were evaluated and compared. Finally, a contribution analysis was conducted to understand the impact of different process factors on AC yield and surface area. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd DA - 2019/7// PY - 2019/7// DO - 10.1002/bbb.1991 VL - 13 IS - 4 SP - 1015-1027 UR - https://doi.org/10.1002/bbb.1991 KW - artificial neural network KW - steam activation KW - activated carbon KW - lignocellulosic biomass ER - TY - JOUR TI - Comparison of real-world vehicle fuel use and tailpipe emissions for gasoline-ethanol fuel blends AU - Yuan, Weichang AU - Frey, H. Christopher AU - Wei, Tongchuan AU - Rastogi, Nikhil AU - VanderGriend, Steven AU - Miller, David AU - Mattison, Lawrence T2 - FUEL AB - Differences in fuel use and emission rates of carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), nitrogen oxide (NOx), and particulate matter (PM) were quantified for three gasoline-ethanol blends and neat gasoline measured for one flexible-fuel vehicle (FFV) and four non-FFVs using a portable emission measurement system (PEMS). The purpose was to determine if non-FFVs can adapt to a mid-level blend and to compare the fuel use and emission rates among the fuels. Each vehicle was measured on neat gasoline (E0), 10% ethanol by volume (E10) “regular” (E10R) and “premium” (E10P), and 27% ethanol by volume (E27). Four real-world cycles were repeated for each vehicle with each fuel. Second-by-second fuel use and emission rates were binned into Vehicle Specific Power (VSP) modes. The modes were weighted according to real-world standard driving cycles. All vehicles, including the non-FFVs, were able to adapt to E27. Octane-induced efficiency gain was observed for higher octane fuels (E10P and E27) versus lower octane fuels (E0 and E10R). E27 tends to lower PM emission rates compared to E10R and E10P and CO emission rates compared to the other three fuels. HC emission rates for E27 were comparable to those of E10R and E10P. No significant difference was found in NOx emission rates for E27 versus the other fuels. Intervehicle variability in fuel use and emission rates was observed. Lessons learned regarding study design, vehicle selection, and sample size, and their implications are discussed. DA - 2019/8/1/ PY - 2019/8/1/ DO - 10.1016/j.fuel.2019.03.115 VL - 249 SP - 352-364 SN - 1873-7153 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85063525708&partnerID=MN8TOARS KW - Ethanol KW - Octane KW - Real-world driving KW - Portable emission measurement system KW - Exhaust emissions ER - TY - JOUR TI - Effects of Sodium and Tungsten Promoters on Mg6MnO8-Based Core-Shell Redox Catalysts for Chemical Looping-Oxidative Dehydrogenation of Ethane AU - Yusuf, Seif AU - Neal, Luke AU - Bao, Zhenghong AU - Wu, Zili AU - Li, Fanxing T2 - ACS CATALYSIS AB - The present study investigates the effect of sodium and tungsten promoters on Mg6MnO8-based redox catalysts in a chemical looping oxidative dehydrogenation (CL-ODH) scheme. CL-ODH has the potential to significantly lower energy consumption and CO2/NOx emissions for ethylene production compared with conventional steam cracking. Sodium tungstate (Na2WO4) was previously shown to be an effective promoter for Mg6MnO8-based redox catalysts. Overall, the CL-ODH reaction proceeds via parallel gas-phase cracking of ethane and selective combustion of H2 on the surface of the Na2WO4-promoted redox catalyst. Reaction testing indicates that both Na and W are necessary to form Na2WO4 and to achieve high ethylene selectivity. A Na:W ratio lower than 2:1 lead to significant formation of additional mixed tungsten oxide phases and decreases ethylene selectivity. Further characterizations based on low-energy ion scattering (LEIS) and differential scanning calorimetry (DSC) indicate that the NaW promoter forms a molten shell around the Mg6MnO8 redox catalyst. Methanol TPSR and in situ DRIFTS experiments indicate that the promoter significantly suppresses the number of basic sites on Mg6MnO8. 18O–16O exchange experiments reveal that the promoter decreases the rate of oxygen exchange. O2 cofeed studies indicate that below the melting temperature of Na2WO4, H2 and CO conversions are both inhibited, but above the melting temperature, H2 combustion significantly increased while CO combustion is still inhibited. On the basis of extensive characterizations, it was determined that H2 is primarily combusted at the gas–Na2WO4 molten shell interface via redox reactions of the tungsten salt, likely between the WO42– (tungstate) and WO3– (tungsten bronze). DA - 2019/4// PY - 2019/4// DO - 10.1021/acscatal.9b00164 VL - 9 IS - 4 SP - 3174-3186 SN - 2155-5435 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85064004480&partnerID=MN8TOARS KW - oxidative dehydrogenation KW - chemical looping KW - redox catalyst KW - oxygen carrier ER - TY - JOUR TI - Dynamic Modeling, Stability, and Control of Power Systems With Distributed Energy Resources AU - Sadamoto, Tomonori AU - Chakrabortty, Aranya AU - Ishizaki, Takayuki AU - Imura, Jun-ichi T2 - IEEE CONTROL SYSTEMS MAGAZINE AB - This article presents an end-to-end differential algebraic model of a power system in its entirety, including synchronous generators, wind farms, solar farms, energy storage, power electronics converters, and controllers for each device. Distributed energy resources (DERs) and power electronics devices are shown to affect small signal stability and the dynamic performance of the grid. The article then presents a two-layer control architecture for future grids, where one layer consists of decentralized plug-and-play controllers for power electronics converter control of DERs, and another layer is composed of system-wide distributed controllers actuated through the generators. DA - 2019/4// PY - 2019/4// DO - 10.1109/MCS.2018.2888680 VL - 39 IS - 2 SP - 34-65 SN - 1941-000X ER - TY - JOUR TI - Building conflict uncertainty into electricity planning: A South Sudan case study AU - Patankar, Neha AU - Queiroz, Anderson Rodrigo AU - DeCarolis, Joseph F. AU - Bazilian, Morgan D. AU - Chattopadhyay, Debabrata T2 - ENERGY FOR SUSTAINABLE DEVELOPMENT AB - This paper explores electricity planning strategies in South Sudan under future conflict uncertainty. A stochastic energy system optimization model that explicitly considers the possibility of armed conflict leading to electric power generator damage is presented. Strategies that hedge against future conflict have the greatest economic value in moderate conflict-related damage scenarios by avoiding expensive near-term investments in infrastructure that may be subsequently damaged. Model results show that solar photovoltaics can play a critical role in South Sudan's future electric power system. In addition to mitigating greenhouse gas emissions and increasing access to electricity, this analysis suggests that solar can be used to hedge against economic losses incurred by conflict. While this analysis focuses on South Sudan, the analytical framework can be applied to other conflict-prone countries. DA - 2019/4// PY - 2019/4// DO - 10.1016/j.esd.2019.01.003 VL - 49 SP - 53-64 SN - 0973-0826 KW - Stochastic programming KW - Conflict uncertainty KW - South Sudan ER - TY - JOUR TI - Adaptability of Populus to Physiography and Growing Conditions in the Southeastern USA AU - Ghezehei, Solomon AU - Nichols, Elizabeth AU - Maier, Christopher AU - Hazel, Dennis T2 - Forests AB - Populus species have a high productivity potential as short-rotation woody crops, provided that site-suitable varieties are planted. The Coastal Plain, the Piedmont, and the Blue Ridge Mountains make up a significant part of the eastern and southeastern USA, and an insight into poplar productivity and adaptability will be valuable for the successful implementation of large-scale poplar stands in these regions. The objectives of this study were to examine the green wood biomass (hereafter biomass), biomass allocation, and wood properties of poplars in relation to growing conditions, physiography, and topography. The biomass of 4-year-old poplars was estimated using an equation derived through destructive sampling. Biomass-based clonal rankings were compared across the various site conditions (fertility, irrigation, land marginality, soil preparation, and topography) and the three physiographic provinces. Although not all clonal differences in biomass were significant, growing conditions, physiography, and soil preparation affected the clonal rankings and the significance of the clonal differences. Biomass changes due to physiography and land conditions were more structured at the genomic-group level. A higher-altitude physiography led to greater biomass increases in Populus trichocarpa × Populus deltoids (TD) clones than in P. deltoids × P. deltoids (DD) clones and vice versa. Favorable soil quality or management generally led to greater biomass of DD clones than of TD and P. deltoids × Populus maximowiczii (DM) clones. Weather-related variables were not clearly correlated with biomass, while land aspect was a significant influence on the biomass of genomic groups and clones. The site significantly affected wood density, moisture content, and carbon and nitrogen concentrations, while the clonal effects on wood composition and the clonal and site effects on biomass allocation were insignificant. Although clones showing greater biomass responses to growing conditions generally belonged to the same genomic group, clone-level selection could produce greater biomass gains than selection at the genomic-group level. DA - 2019/2/2/ PY - 2019/2/2/ DO - 10.3390/f10020118 VL - 10 IS - 2 SP - 118 J2 - Forests LA - en OP - SN - 1999-4907 UR - http://dx.doi.org/10.3390/f10020118 DB - Crossref KW - biomass allocation KW - land marginality KW - Populus KW - physiographic provinces KW - soil preparation KW - topography KW - wood biomass productivity KW - wood composition and properties ER - TY - JOUR TI - Perovskite oxides for redox oxidative cracking of n-hexane under a cyclic redox scheme AU - Dudek, Ryan B. AU - Tian, Xin AU - Blivin, Millicent AU - Neal, Luke M. AU - Zhao, Haibo AU - Li, Fanxing T2 - APPLIED CATALYSIS B-ENVIRONMENTAL AB - Steam cracking of naphtha is a commercially proven technology for light olefin production and the primary source of ethylene in the Europe and Asia-Pacific markets. However, its significant energy consumption and high CO2 intensity (up to 2 tons CO2/ton C2H4), stemming from endothermic cracking reactions and complex product separations, make this state-of-the-art process increasingly undesirable from an environmental standpoint. We propose a redox oxidative cracking (ROC) approach as an alternative pathway for naphtha conversion. Enabled by perovskite oxide-based redox catalysts, the ROC process converts naphtha (represented by n-hexane) in an auto-thermal, cyclic redox mode. The addition of 20 wt.% Na2WO4 to SrMnO3 and CaMnO3 created highly selective redox catalysts capable of achieving enhanced olefin yields from n-hexane oxy-cracking. This was largely attributed to the redox catalysts’ high activity, selectivity, and stability towards selective hydrogen combustion (SHC) under a redox mode. Na2WO4/CaMnO3 demonstrated significantly higher olefin yield (55–58%) when compared to that from thermal cracking (34%) at 725 °C and 4500 h−1. COx yield as low as 1.7% was achieved along with complete combustion of H2 over 25 cycles. Similarly, Na2WO4/SrMnO3 achieved 41% olefin yield, 0.4% COx yield, and 73% H2 combustion at this condition. Oxygen-temperature-programmed desorption (O2-TPD) indicated that Na2WO4 hindered gaseous oxygen release from CaMnO3. Low-energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS) revealed an outermost perovskite surface layer covered by Na2WO4, which suppressed near-surface Mn and alkaline earth metal cations. The formation of non-selective surface oxygen species was also inhibited. XPS analysis further confirmed that promotion of SrMnO3 with Na2WO4 suppressed surface Sr species by 90%, with a similar effect also observed on CaMnO3. These findings point to the promoting effect of Na2WO4 and the potential of promoted SrMnO3 and CaMnO3 as selective redox catalysts for efficient production of light olefins from naphtha via the ROC process. DA - 2019/6/5/ PY - 2019/6/5/ DO - 10.1016/j.apcatb.2019.01.048 VL - 246 SP - 30-40 SN - 1873-3883 UR - https://doi.org/10.1016/j.apcatb.2019.01.048 KW - Oxidative cracking KW - Naphtha KW - Chemical looping KW - Redox catalyst KW - Perovskite ER - TY - JOUR TI - Smart Inverter Volt-Watt Control Design in High PV-Penetrated Distribution Systems AU - Kashani, Mahsa Ghapandar AU - Mobarrez, Maziar AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS AB - Advanced control techniques such as volt-watt and volt-VAR control have been developed for high integration of distributed renewable energy, such as photovoltaic (PV) resources, on an electric distribution system. However, designing these control parameters, which yields the best results in the system, is complicated and depends on feeder conditions. This paper proposes a method to properly design the volt-watt control parameters in smart PV inverters to increase the benefit of their control action. The intention of this control design is to mitigate the voltage violations in a high PV-penetrated distribution feeder, while evenly distributing the weight of energy curtailment among all PV systems. Test results are provided from simulation-only scenarios and a hardware-in-the-loop test platform. DA - 2019/// PY - 2019/// DO - 10.1109/TIA.2018.2878844 VL - 55 IS - 2 SP - 1147-1156 SN - 1939-9367 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85055894035&partnerID=MN8TOARS KW - Photovoltaic (PV) KW - volt-VAR control KW - volt-watt ER - TY - CONF TI - Sparse Wide-Area Control of Power Systems using Data-driven Reinforcement Learning AU - Dizche, A. Fallah AU - Chakrabortty, A. AU - Duel-Hallen, A. C2 - 2019/// DA - 2019/// PB - American Control Conference ER - TY - CONF TI - Coordinated Control of Energy Storage in Networked Microgrids under Unpredicted Load Demands AU - Khan, M.T. AU - Cisneros, R. AU - Chakrabortty, A. AU - Husain, I. C2 - 2019/// DA - 2019/// PB - American Control Conference ER - TY - CONF TI - A passivity-based globally stabilizing PI controller for primary control of radial power distribution systems AU - Milani, A. AU - Cisneros, R. AU - Chakrabortty, A. AU - Husain, I. C2 - 2019/// DA - 2019/// PB - American Control Conference ER - TY - CONF TI - Block-Decentralized Model-Free Reinforcement Learning Control of Two Time-Scale Networks AU - Mukherjee, S. AU - Chakrabortty, A. AU - Bai, H. C2 - 2019/// DA - 2019/// PB - American Control Conference ER - TY - CONF TI - A Cyber-Security Investment Game for Networked Control Systems AU - Shukla, P. AU - Chakrabortty, A. AU - Duel-Hallen, A. C2 - 2019/// DA - 2019/// PB - American Control Conference ER - TY - CONF TI - Online Tuning of Cloud-based Wide-Area Controllers with Variations in Network Traffic AU - Ni, H. AU - Chakrabortty, A. AU - Xin, Y. C2 - 2019/// C3 - IEEE PES General Meeting DA - 2019/// ER - TY - CONF TI - Learning Power System Dynamic Signatures using LSTM-Based Deep Neural Network : A Prototype Study on the New York State Grid AU - Mukherjee, S. AU - Darvishi, A. AU - Chakrabortty, A. AU - Fardanesh, B. C2 - 2019/// C3 - IEEE PES General Meeting DA - 2019/// ER - TY - CONF TI - A Measurement-based Adaptive Power System Damping Control Design using ERA-driven Neural Observer and Reinforcement Learning AU - Mukherjee, S. AU - Chakrabortty, A. AU - Bai, H. C2 - 2019/// C3 - IEEE PES General Meeting DA - 2019/// ER - TY - JOUR TI - Isolation Transformer for 3-Port 3-Phase Dual-Active Bridge Converters in Medium Voltage Level AU - Baek, Seunghun AU - Bhattacharya, Subhashish T2 - IEEE ACCESS AB - In this paper, an isolation transformer with integrated filter inductances for three-phase three-port dual-active bridge (DAB) converters in the wye-wye-delta (Yyd) configuration is introduced and designed. A large number of ports and phases in the application necessarily requires a proportionally increased number of components, accessories, and connections. These additional parts induce significant losses and electromagnetic interference during high-frequency operations. Hence, fully manipulating the parasitic components, especially the leakage inductances of the transformer as the circuit element in the interconnected multi-port configuration, is a key to reduce the system's overall size and to improve its reliability. The proposed geometry and design method enables the full integration of a large number of otherwise bulky inductors to be included in the isolation transformers so that the latter function not only a step-up/down transformers but also as filter networks required for three-port DAB operations. The transformer is suitable for high-power and high step-up/down ratio dc-dc converters, which prefers a parallel combination of converters that share current, on the low-voltage side. The operating principles and steady-state analysis are presented with respect to power flow, and a three-winding shell-type isolation/filter transformer has been designed for a three-port three-phase Yyd DAB converter for solid state transformer applications. The finite element method simulations are used to validate the feasibility of the proposed approach. A prototype was fabricated and tested in an experimental setting. DA - 2019/// PY - 2019/// DO - 10.1109/ACCESS.2019.2895818 VL - 7 SP - 19678-19687 SN - 2169-3536 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85062211518&partnerID=MN8TOARS KW - Dual active bridge converter KW - three-winding transformer KW - solid state transformer ER - TY - JOUR TI - The co-existence of anammox genera in an expanded granular sludge bed reactor with biomass carriers for nitrogen removal AU - Wu, Yang AU - Wang, Yuexing AU - De Costa, Yashika G. AU - Tong, Zhida AU - Cheng, Jay J. AU - Zhou, Lijie AU - Zhuang, Wei-Qin AU - Yu, Ke T2 - APPLIED MICROBIOLOGY AND BIOTECHNOLOGY DA - 2019/2// PY - 2019/2// DO - 10.1007/s00253-018-9494-3 VL - 103 IS - 3 SP - 1231-1242 SN - 1432-0614 KW - Anammox KW - EGSB KW - Nitrogen removal KW - Biomass carriers KW - Microbial communities ER - TY - BOOK TI - Smart Grid Control: Overview and Research Opportunities AU - Stoustrup, Jakob AU - Annaswamy, Anuradha AU - Chakrabortty, Aranya AU - Qu, Zhihua AB - This book focuses on the role of systems and control, provides an overview of the smart grid control landscape, and helps to promote smart grids by demonstrating how it can deal with customer demand and other practical market-related issues such as pricing DA - 2019/// PY - 2019/// DO - 10.1007/978-3-319-98310-3 SE - 1-288 SN - 978-3-319-98309-7 ER - TY - JOUR TI - Research Challenges for Design and Implementation of Wide-Area Control AU - Chakrabortty, Aranya T2 - SMART GRID CONTROL: OVERVIEW AND RESEARCH OPPORTUNITIES AB - The 2003 Northeast blackout uncovered the vulnerability of the US power system, and manifested the urgent need for real-time state monitoring and control of the grid leading to the development of the wide-area measurement systems (WAMS) technology. DA - 2019/// PY - 2019/// DO - 10.1007/978-3-319-98310-3_10 SP - 165-172 ER - TY - JOUR TI - Solid Waste Management Policy Implications on Waste Process Choices and Systemwide Cost and Greenhouse Gas Performance AU - Jaunich, Megan K. AU - Levis, James W. AU - DeCarolis, Joseph F. AU - Barlaz, Morton A. AU - Ranjithan, S. Ranji T2 - Environmental Science & Technology AB - Solid waste management (SWM) is a key function of local government and is critical to protecting human health and the environment. Development of effective SWM strategies should consider comprehensive SWM process choices and policy implications on system-level cost and environmental performance. This analysis evaluated cost and select environmental implications of SWM policies for Wake County, North Carolina using a life-cycle approach. A county-specific data set and scenarios were developed to evaluate alternatives for residential municipal SWM, which included combinations of a mixed waste material recovery facility (MRF), anaerobic digestion, and waste-to-energy combustion in addition to existing SWM infrastructure (composting, landfilling, single stream recycling). Multiple landfill diversion and budget levels were considered for each scenario. At maximum diversion, the greenhouse gas (GHG) mitigation costs ranged from 30 to 900 $/MTCO2e; the lower values were when a mixed waste MRF was used, and the higher values when anaerobic digestion was used. Utilization of the mixed waste MRF was sensitive to the efficiency of material separation and operating cost. Maintaining the current separate collection scheme limited the potential for cost and GHG reductions. Municipalities seeking to cost-effectively increase landfill diversion while reducing GHGs should consider waste-to-energy, mixed waste separation, and changes to collection. DA - 2019/1/11/ PY - 2019/1/11/ DO - 10.1021/acs.est.8b04589 VL - 53 IS - 4 SP - 1766-1775 J2 - Environ. Sci. Technol. LA - en OP - SN - 0013-936X 1520-5851 UR - http://dx.doi.org/10.1021/acs.est.8b04589 DB - Crossref ER - TY - JOUR TI - Wide-Area Communication and Control: A Cyber-Physical Perspective AU - Chakrabortty, Aranya T2 - SMART GRID CONTROL: OVERVIEW AND RESEARCH OPPORTUNITIES AB - For several decades, the traditional mindset for controlling large-scale power systems has been limited to local output feedback control, which means that controllers installed within the operating region of any utility company typically use measurements available only from inside that region for feedback, and, in fact, more commonly only from the vicinity of the controller location. Examples of such controllers include Automatic Voltage Regulators (AVR), Power System Stabilizers (PSS), Automatic Generation Control (AGC), FACTS control, HVDC, and so on. DA - 2019/// PY - 2019/// DO - 10.1007/978-3-319-98310-3_9 SP - 139-164 ER - TY - JOUR TI - Oxygen Vacancy Creation Energy in Mn-Containing Perovskites: An Effective Indicator for Chemical Looping with Oxygen Uncoupling AU - Mishra, Amit AU - Li, Tianyang AU - Li, Fanxing AU - Santiso, Erik E. T2 - CHEMISTRY OF MATERIALS AB - Chemical looping with oxygen uncoupling (CLOU) is a novel process for carbon dioxide capture from coal combustion. Designing a metal oxide oxygen carrier with suitable oxygen release and uptake (redox) properties represents one of the most critical aspects for CLOU. The current work aims to correlate oxygen vacancy creation energy of metal oxide oxygen carriers with their redox properties. Oxygen vacancy creation energies of CaMnO3−δ, Ca0.75Sr0.25MnO3−δ, CaMn0.75Fe0.25O3−δ, and BaMnO3−δ were determined through density functional theory (DFT) calculations. The effect of the Hubbard U correction on the ground state magnetic configurations and vacancy creation energies was investigated, along with the effect of lattice oxygen coordination environment. It was determined that Hubbard U only slightly changes the relative differences in vacancy creation energies between the Mn-containing perovskites investigated. Therefore, ranking of oxygen vacancy creation energies among the various oxides can be determined using a simplified method without using Hubbard U. Comparisons with experimental data confirmed that vacancy creation energy is an effective indicator for oxygen release properties of the perovskites investigated: oxygen carrier materials with lower vacancy creation energies can release their lattice oxygen more readily. Thermogravimetric analysis indicated increased oxygen release with decreasing oxygen vacancy creation energy at temperatures below 700 °C. Higher activities for coal char combustion were also observed. The simplified DFT strategy also satisfactorily predicted the effects of iron and strontium doping on lattice distortions as well as the crystal volume changes upon oxygen vacancy creation. These findings indicate that oxygen vacancy creation energies in Mn-containing perovskites can potentially be used as an effective design parameter for oxygen carrier development and optimizations. DA - 2019/2/12/ PY - 2019/2/12/ DO - 10.1021/acs.chemmater.8b03187 VL - 31 IS - 3 SP - 689-698 SN - 1520-5002 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85061650487&partnerID=MN8TOARS ER - TY - JOUR TI - Indoor Exposure to Ambient Particles and Its Estimation Using Fixed Site Monitors AU - Che, Wenwei AU - Frey, H. Christopher AU - Li, Zhiyuan AU - Lao, Xiangqian AU - Lau, Alexis K. H. T2 - ENVIRONMENTAL SCIENCE & TECHNOLOGY AB - Ambient PM2.5 concentrations measured at fixed site monitors (FSM) are often biased with respect to exposure concentrations because of spatial variability and infiltration. Based on comparison of ambient concentrations from 14 FSMs and of exposure concentrations measured indoors and outdoors at two schools in Hong Kong for winter and summer seasons, the magnitude and sources of exposure error based on using FSMs as a surrogate for exposure are quantified. An approach for bias correcting surrogate exposure estimates from FSMs is demonstrated. The approach is based on a proximity factor (PF) that accounts for differences in spatial locations, proximity to emissions and deviation from dominant wind direction, and an infiltration factor (IF) that varies by season. The combination of the PF and IF reduce bias in mean school exposure estimates from ±90% to ±20%. Bias in exposure estimates from using FSMs as surrogates tend to be smaller for which the exposure site and FSM are aligned with wind direction, have similar sampling height, and are in close proximity. The methodology demonstrated to assess concordance between FSMs and exposure measurement sites can be applied more broadly to help reduce exposure error, which may help to interpret seasonal variations in health estimates. DA - 2019/1/15/ PY - 2019/1/15/ DO - 10.1021/acs.est.8b04474 VL - 53 IS - 2 SP - 808-819 SN - 1520-5851 UR - https://doi.org/10.1021/acs.est.8b04474 ER - TY - JOUR TI - Quantifying the Urban Food-Energy-Water Nexus: The Case of the Detroit Metropolitan Area AU - Liang, Sai AU - Qu, Shen AU - Zhao, Qiaoting AU - Zhang, Xilin AU - Daigger, Glen T. AU - Newell, Joshua P. AU - Miller, Shelie A. AU - Johnson, Jeremiah X. AU - Love, Nancy G. AU - Zhang, Lixiao AU - Yang, Zhifeng AU - Xu, Ming T2 - ENVIRONMENTAL SCIENCE & TECHNOLOGY AB - The efficient provision of food, energy, and water (FEW) resources to cities is challenging around the world. Because of the complex interdependence of urban FEW systems, changing components of one system may lead to ripple effects on other systems. However, the inputs, intersectoral flows, stocks, and outputs of these FEW resources from the perspective of an integrated urban FEW system have not been synthetically characterized. Therefore, a standardized and specific accounting method to describe this system is needed to sustainably manage these FEW resources. Using the Detroit Metropolitan Area (DMA) as a case, this study developed such an accounting method by using material and energy flow analysis to quantify this urban FEW nexus. Our results help identify key processes for improving FEW resource efficiencies of the DMA. These include (1) optimizing the dietary habits of households to improve phosphorus use efficiency, (2) improving effluent-disposal standards for nitrogen removal to reduce nitrogen emission levels, (3) promoting adequate fertilization, and (4) enhancing the maintenance of wastewater collection pipelines. With respect to water use, better efficiency of thermoelectric power plants can help reduce water withdrawals. The method used in this study lays the ground for future urban FEW analyses and modeling. DA - 2019/1/15/ PY - 2019/1/15/ DO - 10.1021/acs.est.8b06240 VL - 53 IS - 2 SP - 779-788 SN - 1520-5851 ER - TY - JOUR TI - A Simple Unified Model for Generic Operation of Dual Active Bridge Converter AU - Shah, Suyash Sushilkumar AU - Bhattacharya, Subhashish T2 - IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS AB - This paper presents a simple and generic model of a dual active bridge converter valid throughout its range of operation. It is suitable for all operating modes and modulation strategies such as phase-shift, extended phaseshift, dual phase-shift, or triple phase-shift modulation. It hypothesizes that any mode of its operation characterized by the duty ratios (d 1 , d 2 ) of the two full-bridge converter ac voltages and the phase shift (φ) between them can be decomposed into four parallel dual active bridge circuits operating in simple phase-shift modulation. The hypothesis is proven mathematically; the average and small-signal models are derived and validated through simulations and experiments on a hardware prototype. DA - 2019/5// PY - 2019/5// DO - 10.1109/TIE.2018.2850012 VL - 66 IS - 5 SP - 3486-3495 SN - 1557-9948 UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85049465467&partnerID=MN8TOARS KW - Bidirectional dc-dc converter KW - double phase shift KW - dual active bridge (DAB) KW - duty ratio modulation KW - extended phase shift KW - large and small signal KW - modeling KW - triangular and trapezoidal modulation KW - triple phase shift ER - TY - JOUR TI - Multiobjective Optimal Siting of Algal Biofuel Production with Municipal Wastewater Treatment in Watersheds with Nutrient Trading Markets AU - Kern, Jordan D. AU - Gorelick, David E. AU - Characklis, Gregory W. AU - Macklin, Caroline M. T2 - JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT AB - Using municipal wastewater effluent as a feedstock in algae cultivation is a promising approach for increasing the commercial viability of algal biofuel production. However, differences in site-specific characteristics at municipal wastewater treatment plants (WWTPs) could drive tradeoffs between maximizing the profitability of algae production and minimizing the cost of meeting water quality standards. A complicating factor is how water quality regulations are enforced, namely the potential presence of nutrient trading markets that would monetize removal of nutrients from wastewater effluent. This study develops an analytical framework for optimizing the siting of an algal biofuel production facility within a network of WWTPs. A combined life cycle assessment (LCA) and techno-economic analysis (TEA) model of an algal biofuel production facility is integrated with a simplified watershed model. An evolutionary algorithm is used to identify optimal sites for algal biofuel production and explore financial tradeoffs for algae biofuel producers and wastewater treatment plants. This analytical framework is then applied to a high-priority, impaired watershed in North Carolina, the Neuse River Basin. DA - 2019/2// PY - 2019/2// DO - 10.1061/(ASCE)WR.1943-5452.0001018 VL - 145 IS - 2 SP - SN - 1943-5452 ER -