Chris Frey

Tulve, N. S., Geller, A. M., Hagerthey, S., Julius, S. H., Lavoie, E. T., Mazur, S. L., … Frey, H. C. (2024). Challenges and opportunities for research supporting cumulative impact assessments at the United States environmental protection agency's office of research and development. Lancet Regional Health - Americas, 30. https://doi.org/10.1016/j.lana.2023.100666

Hu, J., Frey, H. C., & Boroujeni, B. Y. (2023). Contribution of Cold Starts to Real-World Trip Emissions for Light-Duty Gasoline Vehicles. ATMOSPHERE, 14(1). https://doi.org/10.3390/atmos14010035

Rastogi, N., Frey, H. C., & Wei, T. (2023). Identifying emissions hotspots and strategies to reduce real-world fuel use and emissions for passenger rail: A spatially resolved approach. SCIENCE OF THE TOTAL ENVIRONMENT, 896. https://doi.org/10.1016/j.scitotenv.2023.165110

Tulve, N. S., Guiseppi-Elie, A., Geller, A. M., Ward-Caviness, C. K., Paul, S. J., Lavoie, E. T., … Frey, H. C. (2023). Redefining exposure science to advance research supporting cumulative impacts, environmental justice, and decision-making. Journal of Exposure Science and Environmental Epidemiology, 33(6), 843–845. https://doi.org/10.1038/s41370-023-00610-5

Ahn, K., Aredah, A., Rakha, H. A., Wei, T., & Frey, H. C. (2023). Simple Diesel Train Fuel Consumption Model for Real-Time Train Applications. ENERGIES, 16(8). https://doi.org/10.3390/en16083555

Yuan, W., Frey, C., & Wei, T. (2022). Fuel use and emission rates reduction potential for light-duty gasoline vehicle eco-driving. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 109. https://doi.org/10.1016/j.trd.2022.103394

Wei, T., & Frey, H. C. (2022). Intermodal comparison of tailpipe emission rates between transit buses and private vehicles for on-road passenger transport. ATMOSPHERIC ENVIRONMENT, 281. https://doi.org/10.1016/j.atmosenv.2022.119141

Breen, M. S. S., Xu, Y., Frey, H. C., Breen, M., & Isakov, V. (2022, December 16). Microenvironment Tracker (MicroTrac) model to estimate time-location of individuals for air pollution exposure assessments: model evaluation using smartphone data. JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, Vol. 12. https://doi.org/10.1038/s41370-022-00514-w

Eluri, S., & Frey, H. C. (2021). An illustrative case study of the contribution of commuting to PM<sub>2.5</sub>exposures in Hong Kong. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2021-June. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85120584014&partnerID=MN8TOARS

Rastogi, N., & Frey, H. C. (2021). Characterizing Fuel Use and Emission Hotspots for a Diesel-Operated Passenger Rail Service. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 55(15), 10633–10644. https://doi.org/10.1021/acs.est.1c00273

Hossain, M. S., Frey, H. C., Louie, P. K. K., & Lau, A. K. H. (2021). Combined effects of increased O-3 and reduced NO2 concentrations on short-term air pollution health risks in Hong Kong. ENVIRONMENTAL POLLUTION, 270. https://doi.org/10.1016/j.envpol.2020.116280

Che, W., Li, A. T. Y., Frey, H. C., Tang, K. T. J., Sun, L., Wei, P., … Lau, A. K. H. (2021). Factors affecting variability in gaseous and particle microenvironmental air pollutant concentrations in Hong Kong primary and secondary schools. INDOOR AIR, 31(1), 170–187. https://doi.org/10.1111/ina.12725

Hossain, M. S., Che, W., Frey, H. C., & Lau, A. K. H. (2021). Factors affecting variability in infiltration of ambient particle and gaseous pollutants into home at urban environment. BUILDING AND ENVIRONMENT, 206. https://doi.org/10.1016/j.buildenv.2021.108351

Yuan, W., & Frey, H. C. (2021). Multi-scale evaluation of diesel commuter rail fuel use, emissions, and eco-driving. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 99. https://doi.org/10.1016/j.trd.2021.102995

Sandhu, G. S., Frey, H. C., Bartelt-Hunt, S., & Jones, E. (2021). Real-world activity, fuel use, and emissions of heavy-duty compressed natural gas refuse trucks. SCIENCE OF THE TOTAL ENVIRONMENT, 761. https://doi.org/10.1016/j.scitotenv.2020.143323

Wei, T., & Frey, H. C. (2021, June 10). Sensitivity of light duty vehicle tailpipe emission rates from simplified portable emission measurement systems to variation in engine volumetric efficiency. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, Vol. 6. https://doi.org/10.1080/10962247.2021.1923586

Wei, T., Frey, H. C., & Yuan, W. (2020). Application of transit bus emissions model to emission estimation: Case study for a wolfline transit bus line at North Carolina State University. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2020-June. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85104853939&partnerID=MN8TOARS

Frey, H. C. (2020). Effect of changes since 2017 on the quality, credibility, and integrity of scientific review of national ambient air quality standards. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2020-June. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85104833715&partnerID=MN8TOARS

Wei, T., & Frey, H. C. (2020). Evaluation of the Precision and Accuracy of Cycle-Average Light Duty Gasoline Vehicles Tailpipe Emission Rates Predicted by Modal Models. TRANSPORTATION RESEARCH RECORD, 2674(7), 566–584. https://doi.org/10.1177/0361198120924006

Wei, T., & Frey, H. C. (2020). Factors affecting variability in fossil-fueled transit bus emission rates. ATMOSPHERIC ENVIRONMENT, 233. https://doi.org/10.1016/j.atmosenv.2020.117613

Khan, T., Frey, H. C., Rastogi, N., & Wei, T. (2020). Geospatial Variation of Real-World Tailpipe Emission Rates for Light-Duty Gasoline Vehicles. Environmental Science & Technology, 54(14), 8968–8979. https://doi.org/10.1021/acs.est.0c00489

Rastogi, N., & Frey, H. C. (2020). Locomotive fuel use and emission rates: Effects of transients and train consists. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2020-June. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85104863944&partnerID=MN8TOARS

Che, W., Frey, H. C., Fung, J. C. H., Ning, Z., Qu, H., Lo, H. K., … Lau, A. K. H. (2020). PRAISE -HK: A personalized real-time air quality informatics system for citizen participation in exposure and health risk management. SUSTAINABLE CITIES AND SOCIETY, 54. https://doi.org/10.1016/j.scs.2019.101986

Yuan, W., & Frey, H. C. (2020). Potential for metro rail energy savings and emissions reduction via eco-driving. APPLIED ENERGY, 268. https://doi.org/10.1016/j.apenergy.2020.114944

Yuan, W., & Frey, H. C. (2020). Potential for subway energy savings and emissions reductions based on inter-run variability in speed trajectories: A case study of Baltimore subway. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2020-June. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85104829385&partnerID=MN8TOARS

Frey, H. C., Gadre, D., Singh, S., & Kumar, P. (2020). Quantification of Sources of Variability of Air Pollutant Exposure Concentrations Among Selected Transportation Microenvironments. TRANSPORTATION RESEARCH RECORD, 2674(9), 395–411. https://doi.org/10.1177/0361198120929336

Frey, H. C., Adams, P. J., Adgate, J. L., Allen, G. A., Balmes, J., Boyle, K., … Wyzga, R. (2020). The need for a tighter particulate-matter air-quality standard. New England Journal of Medicine, 383(7), 680–683. https://doi.org/10.1056/NEJMsb2011009

Frey, H. C., Zheng, X., & Hu, J. (2020). Variability in Measured Real-World Operational Energy Use and Emission Rates of a Plug-In Hybrid Electric Vehicle. Energies, 13(5). https://doi.org/10.3390/en13051140

Bunds, K. S., Casper, J. M., Frey, H. C., & Barrett, M. (2019). Air Pollution at College Football Games: Developing a Methodology for Measuring Air Pollutant Exposure in a Sport Event Microenvironment. Event Management, 23(3), 399–412. https://doi.org/10.3727/152599518X15403853721484

Yuan, W., Frey, H. C., Wei, T., Rastogi, N., VanderGriend, S., Miller, D., & Mattison, L. (2019). Comparison of real-world vehicle fuel use and tailpipe emissions for gasoline-ethanol fuel blends. FUEL, 249, 352–364. https://doi.org/10.1016/j.fuel.2019.03.115

Khan, T., & Frey, H. C. (2019). Effect of Air-Conditioning on Light Duty Gasoline Vehicles Fuel Economy. TRANSPORTATION RESEARCH RECORD, 2673(5), 131–141. https://doi.org/10.1177/0361198119838507

Che, W., Frey, H. C., Li, Z., Lao, X., & Lau, A. K. H. (2019). Indoor Exposure to Ambient Particles and Its Estimation Using Fixed Site Monitors. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 53(2), 808–819. https://doi.org/10.1021/acs.est.8b04474

Yuan, W., Frey, H. C., & Rastogi, N. (2019). Quantification of Energy Saving Potential for A Passenger Train Based on Inter-Run Variability in Speed Trajectories. TRANSPORTATION RESEARCH RECORD, 2673(5), 153–165. https://doi.org/10.1177/0361198119838516

Kumar, P., Patton, A. P., Durant, J. L., & Frey, H. C. (2018). A review of factors impacting exposure to PM2.5, ultrafine particles and black carbon in Asian transport microenvironments. Atmospheric Environment, 187, 301–316. https://doi.org/10.1016/J.ATMOSENV.2018.05.046

Khan, T., & Frey, H. C. (2018). Comparison of real-world and certification emission rates for light duty gasoline vehicles. SCIENCE OF THE TOTAL ENVIRONMENT, 622, 790–800. https://doi.org/10.1016/j.scitotenv.2017.10.286

Kumar, P., Rivas, I., Singh, A. P., Ganesh, V. J., Ananya, M., & Frey, H. C. (2018). Dynamics of coarse and fine particle exposure in transport microenvironments. NPJ CLIMATE AND ATMOSPHERIC SCIENCE, 1(1). https://doi.org/10.1038/s41612-018-0023-y

Tanvir, S., Frey, H. C., & Rouphail, N. M. (2018). Effect of Light Duty Vehicle Performance on a Driving Style Metric. TRANSPORTATION RESEARCH RECORD, 2672(25), 67–78. https://doi.org/10.1177/0361198118796070

Li, Z., Che, W., Frey, H. C., & Lau, A. K. H. (2018). Factors affecting variability in PM 2.5 exposure concentrations in a metro system. Environmental Research, 160, 20–26. https://doi.org/10.1016/J.ENVRES.2017.09.006

Delavarrafiee, M., & Frey, H. C. (2018). Real-world fuel use and gaseous emission rates for flex fuel vehicles operated on E85 versus gasoline. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 68(3), 235–254. https://doi.org/10.1080/10962247.2017.1405097

Altshuler, S. L., Ayala, A., Collet, S., Chow, J. C., Frey, H. C., Shaikh, R., … Watson, J. G. (2018). Trends in on-road transportation, energy, and emissions. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 68(10), 1015–1024. https://doi.org/10.1080/10962247.2018.1512734

Frey, H. C. (2018). [Review of Trends in onroad transportation energy and emissions]. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 68(6), 514–563. https://doi.org/10.1080/10962247.2018.1454357

Li, Z., Che, W., Frey, H. C., Lau, A. K. H., & Lin, C. (2017). Characterization of PM2.5 exposure concentration in transport microenvironments using portable monitors. ENVIRONMENTAL POLLUTION, 228, 433–442. https://doi.org/10.1016/j.envpol.2017.05.039

Wei, T., Khan, T., & Frey, H. C. (2017). Development of simplified models of CNG, diesel, and hybrid transit bus energy use. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85039153359&partnerID=MN8TOARS

Frey, H. C. (2017). Identifying and transcending ideological barriers in the climate change public policy debate. Air and Waste Management Association, A and WMA - Finding Common Ground on Climate Change Mitigation and Adaptation, 2017-October, 8–17. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85052332630&partnerID=MN8TOARS

Khan, T., & Frey, H. C. (2017). Key factors affecting inter-county variability in moves county-level energy inventory. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85039169682&partnerID=MN8TOARS

Rastogi, N., & Frey, H. C. (2017). Procedure for evaluation of retrofitted scr-based emission control system for a passenger railroad locomotive. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85039160003&partnerID=MN8TOARS

Singh, S., & Frey, H. C. (2017). Procedure for measuring and comparing fuel use and gaseous emissions for gas-direct injection versus port fuel injection vehicles. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85039147517&partnerID=MN8TOARS

Yuan, W., Frey, H. C., & Sun, Y. (2017). Quantification of transit train activity data for energy consumption estimation. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85039168169&partnerID=MN8TOARS

Frey, H. C., Delavarrafiee, M., & Singh, S. (2017). Real-World Freeway and Ramp Activity and Emissions for Light-Duty Gasoline Vehicles. TRANSPORTATION RESEARCH RECORD, 2627(2627), 17–25. https://doi.org/10.3141/2627-03

Rastogi, N., & Frey, H. C. (2016). Assessing the impact of real-world driving cycles, fuel economy and tailpipe exhaust emissions on eco-rating of passenger cars. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 4, 2758–2783. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85014833745&partnerID=MN8TOARS

Hu, J., Frey, H. C., & Washburn, S. S. (2016). Comparison of Vehicle-Specific Fuel Use and Emissions Models Based on Externally and Internally Observable Activity Data. TRANSPORTATION RESEARCH RECORD, 2570(2570), 30–38. https://doi.org/10.3141/2570-04

Frey, H. C. (2016, September). Dose-Response Models are Conditional on Determination of Causality. RISK ANALYSIS, Vol. 36, pp. 1751–1754. https://doi.org/10.1111/risa.12672

Graver, B. M., Frey, H. C., & Hu, J. (2016). Effect of Biodiesel Fuels on Real-World Emissions of Passenger Locomotives. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 50(21), 12030–12039. https://doi.org/10.1021/acs.est.6b03567

Khan, T., & Frey, H. C. (2016). Evaluation of Light-Duty Gasoline Vehicle Rated Fuel Economy Based on In-Use Measurements. TRANSPORTATION RESEARCH RECORD, 2570(2570), 21–29. https://doi.org/10.3141/2570-03

Singh, S., & Frey, H. C. (2016). Gasoline vehicle fuel efficiency and emissions for gas-direct injection versus port-fuel injection. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 4, 2823–2844. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85014864810&partnerID=MN8TOARS

Khan, T., & Frey, H. C. (2016). Geospatial variation of real-world emissions from a passenger car. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 4, 2799–2822. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85014820615&partnerID=MN8TOARS

Graver, B. M., & Frey, H. C. (2016). Highway Vehicle Emissions Avoided by Diesel Passenger Rail Service Based on Real-World Data. Urban Rail Transit, 2(3-4), 153–171. https://doi.org/10.1007/s40864-016-0044-y

Delavarrafiee, M., & Frey, H. C. (2016). Procedure for real-world measurement and data analysis of a flex fuel vehicle operated on E85. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 4, 2689–2714. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-85014816584&partnerID=MN8TOARS

Sandhu, G. S., Frey, H. C., Bartelt-Hunt, S., & Jones, E. (2016). Real-world activity, fuel use, and emissions of diesel side-loader refuse trucks. ATMOSPHERIC ENVIRONMENT, 129, 98–104. https://doi.org/10.1016/j.atmosenv.2016.01.014

Che, W. W., Frey, H. C., & Lau, A. K. H. (2016). Sequential Measurement of Intermodal Variability in Public Transportation PM2.5 and CO Exposure Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 50(16), 8760–8769. https://doi.org/10.1021/acs.est.6b01594

Frey, H. C. (2015). A scientific perspective on the challenges and opportunities for: Multipollutant approaches to air quality management. EM: Air and Waste Management Association's Magazine for Environmental Managers, pp. 24–29. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84920474504&partnerID=MN8TOARS

Frey, H. C. (2015). Clean Air Scientific Advisory Committee advice on the ozone standards. EM: Air and Waste Management Association's Magazine for Environmental Managers, Vol. 65, pp. 9–10. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84946154078&partnerID=MN8TOARS

Graver, B. M., & Frey, H. C. (2015). Comparison of Over-the-Rail and Rail Yard Measurements of Diesel Locomotives. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 49(21), 13031–13039. https://doi.org/10.1021/acs.est.5b02497

Che, W. W., Frey, H. C., & Lau, A. K. H. (2015). Comparison of Sources of Variability in School Age Children Exposure to Ambient PM2.5. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 49(3), 1511–1520. https://doi.org/10.1021/es506275c

Sandhu, G. S., Frey, H. C., Bartelt-Hunt, S., & Jones, E. (2015). Comparison of real-world and MOVES estimated emissions for heavy-duty diesel refuse trucks. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3, 1702–1711. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84983775253&partnerID=MN8TOARS

Sandhu, G. S., Frey, H. C., Bartelt-Hunt, S., & Jones, E. (2015). In-use activity, fuel use, and emissions of heavy-duty diesel roll-off refuse trucks. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 65(3), 306–323. https://doi.org/10.1080/10962247.2014.990587

Zhou, X., Tanvir, S., Lei, H., Taylor, J., Liu, B., Rouphail, N. M., & Frey, H. C. (2015). Integrating a simplified emission estimation model and mesoscopic dynamic traffic simulator to efficiently evaluate emission impacts of traffic management strategies. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 37, 123–136. https://doi.org/10.1016/j.trd.2015.04.013

Liu, B., & Frey, H. C. (2015). Measurement and Evaluation of Real-World Speed and Acceleration Activity Envelopes for Light-Duty Vehicles. TRANSPORTATION RESEARCH RECORD, 2503(2503), 128–136. https://doi.org/10.3141/2503-14

Salamati, K., Rouphail, N. M., Frey, H. C., Liu, B., & Schroeder, B. J. (2015). Simplified method for comparing emissions in roundabouts and at signalized intersections. Transportation Research Record, 2517(2517), 48–60. https://doi.org/10.3141/2517-06

Liu, B., & Frey, H. C. (2015). Variability in Light-Duty Gasoline Vehicle Emission Factors from Trip-Based Real-World Measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 49(20), 12525–12534. https://doi.org/10.1021/acs.est.5b00553

Anya, A., Rouphail, N., Frey, H., & Schroeder, B. (2014). Application of AIMSUN microsimulation model to estimate emissions on signalized arterial corridors. Transportation Research Record, 2428(2428), 75–86. https://doi.org/10.3141/2428-09

Che, W. W., Frey, H. C., & Lau, A. K. H. (2014). Assessment of the Effect of Population and Diary Sampling Methods on Estimation of School-Age Children Exposure to Fine Particles. RISK ANALYSIS, 34(12), 2066–2079. https://doi.org/10.1111/risa.12238

Jiao, W., & Frey, H. C. (2014). Comparison of Fine Particulate Matter and Carbon Monoxide Exposure Concentrations for Selected Transportation Modes. TRANSPORTATION RESEARCH RECORD, (2428), 54–62. https://doi.org/10.3141/2428-07

Graver, B. M., Hu, J., & Frey, H. C. (2014). Comparison of real-world emission rates of a locomotive engine operating on diesel and biodiesel. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 991–999. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84939813222&partnerID=MN8TOARS

Che, W., Frey, H. C., Lau, A. K. H., & Fung, J. C. H. (2014). Geographic and seasonal variations in air exchange rate and their impacts on the estimation of children's exposure to ambient PM<sub>2.5</sub>. Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 836–839. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84924657052&partnerID=MN8TOARS

Sandhu, G. S., Frey, H. C., Bartelt-Hunt, S., & Jones, E. (2014). In-use measurement of the activity, fuel use, and emissions of front-loader refuse trucks. ATMOSPHERIC ENVIRONMENT, 92, 557–565. https://doi.org/10.1016/j.atmosenv.2014.04.036

Hu, J., Frey, H. C., Sandhu, G. S., Graver, B. M., Bishop, G. A., Schuchmann, B. G., & Ray, J. D. (2014). Method for Modeling Driving Cycles, Fuel Use, and Emissions for Over Snow Vehicles. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 48(14), 8258–8265. https://doi.org/10.1021/es501164j

Boroujeni, B. Y., & Frey, H. C. (2014). Road grade quantification based on global positioning system data obtained from real-world vehicle fuel use and emissions measurements. ATMOSPHERIC ENVIRONMENT, 85, 179–186. https://doi.org/10.1016/j.atmosenv.2013.12.025

Mannshardt, E., Sucic, K., Jiao, W., Dominici, F., Frey, H. C., Reich, B., & Fuentes, M. (2013). Comparing exposure metrics for the effects of fine particulate matter on emergency hospital admissions. JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, 23(6), 627–636. https://doi.org/10.1038/jes.2013.39

Graver, B. M., & Frey, H. C. (2013). Comparison of Locomotive Emissions Measured During Dynamometer Versus Rail Yard Engine Load Tests. TRANSPORTATION RESEARCH RECORD, (2341), 23–33. https://doi.org/10.3141/2341-03

Sandhu, G., & Frey, H. (2013). Effects of errors on vehicle emission rates from portable emissions measurement systems. Transportation Research Record, (2340), 10–19. https://doi.org/10.3141/2340-02

Salamati, K., Coelho, M., Fernandes, P., Rouphail, N., Frey, H., & Bandeira, J. (2013). Emissions estimation at multilane roundabouts. Transportation Research Record, (2389), 12–21. https://doi.org/10.3141/2389-02

Salamati, K., Coelho, M. C., Fernandes, P. J., Rouphail, N. M., Frey, H. C., & Bandeira, J. (2013). Emissions estimation at multilane roundabouts effects of movement and approach lane. Transportation Research Record, (2389), 12–21.

Abolhasani, S., & Frey, H. C. (2013). Engine and Duty Cycle Variability in Diesel Construction Equipment Emissions. JOURNAL OF ENVIRONMENTAL ENGINEERING, 139(2), 261–268. https://doi.org/10.1061/(asce)ee.1943-7870.0000548

Jiao, W., & Frey, H. C. (2013). Method for Measuring the Ratio of In-Vehicle to Near-Vehicle Exposure Concentrations of Airborne Fine Particles. TRANSPORTATION RESEARCH RECORD, (2341), 34–42. https://doi.org/10.3141/2341-04

Boroujeni, B. Y., Frey, H. C., & Sandhu, G. S. (2013). Road Grade Measurement Using In-Vehicle, Stand-Alone GPS with Barometric Altimeter. JOURNAL OF TRANSPORTATION ENGINEERING-ASCE, 139(6), 605–611. https://doi.org/10.1061/(asce)te.1943-5436.0000545

Jiao, W., Frey, H. C., & Cao, Y. (2012). Assessment of Inter-Individual, Geographic, and Seasonal Variability in Estimated Human Exposure to Fine Particles. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 46(22), 12519–12526. https://doi.org/10.1021/es302803g

Lewis, P., Rasdorf, W., Frey, H. C., & Leming, M. (2012). Effects of Engine Idling on National Ambient Air Quality Standards Criteria Pollutant Emissions from Nonroad Diesel Construction Equipment. TRANSPORTATION RESEARCH RECORD, (2270), 67–75. https://doi.org/10.3141/2270-09

Sandhu, G. S., & Frey, C. H. (2012). Energy use and emissions from diesel and biodiesel blends for earthmoving equipment. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 609–616. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84907338054&partnerID=MN8TOARS

Graver, B. M., & Christopher Frey, H. (2012). Estimation of light-duty gasoline vehicle emissions avoided by passenger rail service in North Carolina. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 1001–1007. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84876198041&partnerID=MN8TOARS

Rasdorf, W., Lewis, P., Marshall, S. K., Arocho, I., & Frey, H. C. (2012). Evaluation of On-Site Fuel Use and Emissions over the Duration of a Commercial Building Project. JOURNAL OF INFRASTRUCTURE SYSTEMS, 18(2), 119–129. https://doi.org/10.1061/(asce)is.1943-555x.0000071

Lee, T., & Frey, H. C. (2012). Evaluation of representativeness of site-specific fuel-based vehicle emission factors for route average emissions. Environmental Science and Technology, 46(12), 6867–6873. https://doi.org/10.1021/es204451z

Marshall, S. K., Rasdorf, W., Lewis, P., & Frey, H. C. (2012). Methodology for Estimating Emissions Inventories for Commercial Building Projects. Journal of Architectural Engineering, 18(3), 251–260. https://doi.org/10.1061/(ASCE)AE.1943-5568.0000073

Cao, Y., & Frey, H. C. (2012). Modeling of Human Exposure to In-Vehicle PM2.5 from Environmental Tobacco Smoke. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 18(3), 608–626. https://doi.org/10.1080/10807039.2012.672894

Frey, H. C., Choi, H.-W., & Kim, K. (2012). Portable Emission Measurement System for Emissions of Passenger Rail Locomotives. TRANSPORTATION RESEARCH RECORD, (2289), 56–63. https://doi.org/10.3141/2289-08

Sandhu, G., & Frey, H. (2012). Real-world measurement and evaluation of duty cycles, fuels, and emission control technologies of heavy-duty trucks. Transportation Research Record, (2270), 180–187. https://doi.org/10.3141/2270-21

Frey, H. C., & Zhu, Y. (2012). Techno-economic analysis of combined cycle systems. In Combined Cycle Systems for Near-Zero Emission Power Generation (pp. 306–328). https://doi.org/10.1016/B978-0-85709-013-3.50011-0

Chang, H. H., Fuentes, M., & Frey, H. C. (2012). Time series analysis of personal exposure to ambient air pollution and mortality using an exposure simulator. JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, 22(5), 483–488. https://doi.org/10.1038/jes.2012.53

Lewis, P., Leming, M., Frey, H. C., & Rasdorf, W. (2011). Assessing Effects of Operational Efficiency on Pollutant Emissions of Nonroad Diesel Construction Equipment. TRANSPORTATION RESEARCH RECORD, (2233), 11–18. https://doi.org/10.3141/2233-02

Cao, Y., & Frey, H. C. (2011). Assessment of Interindividual and Geographic Variability in Human Exposure to Fine Particulate Matter in Environmental Tobacco Smoke. Risk Analysis, 31(4), 578–591. https://doi.org/10.1111/j.1539-6924.2010.01523.x

Liu, B., & Frey, H. C. (2011). Comparison of driving schedule project level MOVES emission factors to empirical data. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3, 2445–2454. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859175012&partnerID=MN8TOARS

Sun, Y., & Frey, H. C. (2011). Comparison of real-world activity, fuel use, and emissions for selected light duty gasoline vehicles based on driving cycles. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 600–607. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859094415&partnerID=MN8TOARS

Zhai, H., Frey, H. C., & Rouphail, N. M. (2011). Development of a modal emissions model for a hybrid electric vehicle. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 16(6), 444–450. https://doi.org/10.1016/j.trd.2011.05.001

Graver, B. M., & Frey, H. C. (2011). Fuel use and emission rates for F59PH locomotive engines tested on an engine dynamometer. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 614–619. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859054969&partnerID=MN8TOARS

Cao, Y., & Frey, H. C. (2011). Geographic differences in inter-individual variability of human exposure to fine particulate matter. ATMOSPHERIC ENVIRONMENT, 45(32), 5684–5691. https://doi.org/10.1016/j.atmosenv.2011.07.034

Graver, B. M., Frey, H. C., & Choi, H.-W. (2011). In-Use Measurement of Activity, Energy Use, and Emissions of a Plug-in Hybrid Electric Vehicle. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 45(20), 9044–9051. https://doi.org/10.1021/es201165d

Frey, H. C., Sandhu, G. S., Sun, Y., Lee, T., Swidan, H., Liu, B., & Babaee, S. (2011). Incorporating vehicle portable emissions measurement systems into the classroom. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 620–637. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859028524&partnerID=MN8TOARS

Graver, B. M., & Frey, H. C. (2011). Modeling of hybrid and plug-in hybrid electric vehicle energy use and emissions based on in-use measurement. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 608–613. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859038443&partnerID=MN8TOARS

Liu, X., & Frey, H. C. (2011). Modeling of in-vehicle human exposure to ambient fine particulate matter. ATMOSPHERIC ENVIRONMENT, 45(27), 4745–4752. https://doi.org/10.1016/j.atmosenv.2011.04.019

Lee, T., & Frey, H. C. (2011). Variability in gram per gallon vehicle emission factors with engine load and among driving cycles. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3, 2335–2341. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-84859179711&partnerID=MN8TOARS

Frey, H. C., Choi, H.-W., Graver, B. M., & Sandhu, G. S. (2010). Comparative assessment of passenger railroad locomotives using portable emission measurement systems. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 7, 5249–5255. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-79956260289&partnerID=MN8TOARS

Frey, H. C., Rasdorf, W., & Lewis, P. (2010). Comprehensive Field Study of Fuel Use and Emissions of Nonroad Diesel Construction Equipment. TRANSPORTATION RESEARCH RECORD, (2158), 69–76. https://doi.org/10.3141/2158-09

Choi, H.-W., & Frey, H. C. (2010). Estimating Diesel Vehicle Emission Factors at Constant and High Speeds for Short Road Segments. TRANSPORTATION RESEARCH RECORD, (2158), 19–27. https://doi.org/10.3141/2158-03

Liu, X., Frey, H. C., & Cao, Y. (2010). Estimating In-Vehicle Concentration of and Exposure to Fine Particulate Matter Near-Roadway Ambient Air Quality and Variability in Vehicle Operation. TRANSPORTATION RESEARCH RECORD, (2158), 105–112. https://doi.org/10.3141/2158-13

Rasdorf, W., Lewis, P., & Frey, H. C. (2010). Estimating productivity-based fuel eifficiency and emissions factors of diesel construction equipment performing earthmoving activities. In N. M. B. Chimay J. Anumba, John Messner, & M. K. Parfitt (Eds.), Proceedings of the 6th International Conference on Innovation in Architecture, Engineering, and Construction. University Park, Pa. : Department of Architectural Engineering, Pennsylvania State University.

Rasdorf, W., Frey, C., Lewis, P., Kim, K., Pang, S.-H., & Abolhassani, S. (2010). Field Procedures for Real-World Measurements of Emissions from Diesel Construction Vehicles. JOURNAL OF INFRASTRUCTURE SYSTEMS, 16(3), 216–225. https://doi.org/10.1061/(asce)is.1943-555x.0000027

Zhu, Y., & Frey, H. C. (2010). Integrated gasification combined cycle (IGCC) power plant design and technology. In Advanced Power Plant Materials, Design and Technology (pp. 54–88). https://doi.org/10.1533/9781845699468.1.54

Frey, H. C., Choi, H.-W., Graver, B. M., & Sandhu, G. S. (2010). Measurement and comparison of locomotive engine emissions. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 7, 5272–5280. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-79956274785&partnerID=MN8TOARS

Choi, H.-W., & Frey, H. C. (2010). Method for in-use measurement and evaluation of the activity, fuel use, electricity use, and emissions of a plug-in hybrid diesel-electric school bus. Environmental Science and Technology, 44(9), 3601–3607. https://doi.org/10.1021/es903330k

Graver, B. M., & Frey, H. C. (2010). Quantifying the microscale activity, energy use, and emissions of a plug-in hybrid electric vehicle based on in-use data. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 1, 23–45. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-79956211810&partnerID=MN8TOARS

Frey, H. C., Zhang, K., & Rouphail, N. M. (2010). Vehicle-Specific Emissions Modeling Based upon on-Road Measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 44(9), 3594–3600. https://doi.org/10.1021/es902835h

Frey, H. C., & Hubbell, B. (2009). A risk-based assessment and management framework for multipollutant air quality. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 1068–1080. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-77952278636&partnerID=MN8TOARS

Oezkaynak, H., Frey, H. C., Burke, J., & Pinder, R. W. (2009). Analysis of coupled model uncertainties in source-to-dose modeling of human exposures to ambient air pollution: A PM2.5 case study. ATMOSPHERIC ENVIRONMENT, 43(9), 1641–1649. https://doi.org/10.1016/j.atmosenv.2008.12.008

Coelho, M. C., Frey, H. C., Rouphail, N. M., Zhai, H., & Pelkmans, L. (2009). Assessing methods for comparing emissions from gasoline and diesel light-duty vehicles based on microscale measurements. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 14(2), 91–99. https://doi.org/10.1016/j.trd.2008.11.005

Zhai, H., Frey, H. C., Rouphail, N. M., Goncalves, G. A., & Farias, T. L. (2009). Comparison of Flexible Fuel Vehicle and Life-Cycle Fuel Consumption and Emissions of Selected Pollutants and Greenhouse Gases for Ethanol 85 Versus Gasoline. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 59(8), 912–924. https://doi.org/10.3155/1047-3289.59.8.912

Lewis, P., Frey, H. C., & Rasdorf, W. (2009). Development and Use of Emissions Inventories for Construction Vehicles. TRANSPORTATION RESEARCH RECORD, (2123), 46–53. https://doi.org/10.3141/2123-06

Frey, H. C., Kuo, P.-Y., & Villa, C. (2009). Effects of Idle Reduction Technologies on Real World Fuel Use and Exhaust Emissions of Idling Long-Haul Trucks. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 43(17), 6875–6881. https://doi.org/10.1021/es900186e

Graver, B. M., & Frey, H. C. (2009). Estimation of air carrier emissions at Raleigh-Durham international airport. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 4, 2502–2516. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-77952383333&partnerID=MN8TOARS

Frey, H. C., Choi, H.-W., Pritchard, E., & Lawrence, J. (2009). In-use measurement of the activity, energy use, and emissions of a plug-in hybrid electric vehicle. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 1127–1144. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-77952244297&partnerID=MN8TOARS

Frey, H. C., & Kim, K. (2009). In-use measurement of the activity, fuel use, and emissions of eight cement mixer trucks operated on each of petroleum diesel and soy-based B20 biodiesel. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 14(8), 585–592. https://doi.org/10.1016/j.trd.2009.08.004

Pang, S.-H., Frey, H. C., & Rasdorf, W. J. (2009). Life Cycle Inventory Energy Consumption and Emissions for Biodiesel versus Petroleum Diesel Fueled Construction Vehicles. Environmental Science & Technology, 43(16), 6398–6405. https://doi.org/10.1021/es802916u

Pang, S. H., Frey, H. C., & Rasdorf, W. J. (2009). Life cycle inventory energy consumption and emissions for biodiesel versus petroleum diesel fueled construction vehicles. Environmental Science & Technology, 43(16), 6398–6405. https://doi.org/10.1021/os802916u

Choi, H.-W., & Frey, H. C. (2009). Light duty gasoline vehicle emission factors at high transient and constant speeds for short road segments. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 14(8), 610–614. https://doi.org/10.1016/j.trd.2009.09.001

Frey, H. C., Choi, H.-W., & Kim, K. (2009). Measurement of the energy use and emissions of passenger rail locomotives using a portable emission measurement system. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 1145–1157. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-77952268050&partnerID=MN8TOARS

Liu, X., Frey, H. C., Cao, Y., & Deshpande, B. (2009). Modeling of in-vehicle PM2.5 exposure using the stochastic human exposure and dose simulation model. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2, 1087–1100. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-77952286694&partnerID=MN8TOARS

Bogen, K. T., Cullen, A. C., Frey, H. C., & Price, P. S. (2009). [Review of Probabilistic Exposure Analysis for Chemical Risk Characterization]. TOXICOLOGICAL SCIENCES, 109(1), 4–17. https://doi.org/10.1093/toxsci/kfp036

Frey, H. C., & Kuo, P.-Y. (2009). Real-World Energy Use and Emission Rates for Idling Long-Haul Trucks and Selected Idle Reduction Technologies. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 59(7), 857–864. https://doi.org/10.3155/1047-3289.59.7.857

Frey, H. C., Zhai, H., & Rouphail, N. M. (2009). Regional On-Road Vehicle Running Emissions Modeling and Evaluation for Conventional and Alternative Vehicle Technologies. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 43(21), 8449–8455. https://doi.org/10.1021/es900535s

Lewis, P., Rasdorf, W., Frey, H. C., Pang, S.-H., & Kim, K. (2009). Requirements and Incentives for Reducing Construction Vehicle Emissions and Comparison of Nonroad Diesel Engine Emissions Data Sources. JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT-ASCE, 135(5), 341–351. https://doi.org/10.1061/(ASCE)CO.1943-7862.0000008

Zhai, H., Frey, H. C., & Rouphail, N. M. (2008). A Vehicle-Specific Power Approach to Speed- and Facility-Specific Emissions Estimates for Diesel Transit Buses. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 42(21), 7985–7991. https://doi.org/10.1021/es800208d

Frey, H. C., Kim, K., Pang, S.-H., Rasdorf, W. J., & Lewis, P. (2008). Characterization of Real-World Activity, Fuel Use, and Emissions for Selected Motor Graders Fueled with Petroleum Diesel and B20 Biodiesel. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 58(10), 1274–1287. https://doi.org/10.3155/1047-3289.58.10.1274

Özkaynak, H., Frey, H. C., & Hubbell, B. (2008). Characterizing variability and uncertainty in exposure assessments improves links to environmental decision-making. EM: Air and Waste Management Association's Magazine for Environmental Managers, pp. 18–22. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-47749136225&partnerID=MN8TOARS

Frey, H. C., Rasdorf, W., Kim, K., Pang, G.-hao, & Lewis, P. (2008). Comparison of Real-World Emissions of B20 Biodiesel Versus Petroleum Diesel for Selected Nonroad Vehicles and Engine Tiers. TRANSPORTATION RESEARCH RECORD, (2058), 33–42. https://doi.org/10.3141/2058-05

Zhai, H., Frey, H. C., Rouphail, N. M., Gonçalves, G. A., & Farias, T. L. (2008). Comparison of fuel consumption and tailpipe emissions of ethanol 85 and gasoline for flexible fuel vehicles. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3262–3276. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-70449498143&partnerID=MN8TOARS

Frey, H. C., & Choi, H.-W. (2008). Estimating light duty gasoline vehicle emission factors at high transient and constant speeds for short road segments to support near-roadway air quality studies. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3137–3148. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-70449500370&partnerID=MN8TOARS

Zhang, K., & Frey, C. (2008). Evaluation of response time of a portable system for in-use vehicle tailpipe emissions measurement. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 42(1), 221–227. https://doi.org/10.1021/es062999h

Frey, H. C., Zhang, K., & Rouphail, N. M. (2008). Fuel use and emissions comparisons for alternative routes, time of day, road grade, and vehicles based on in-use measurements. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 42(7), 2483–2489. https://doi.org/10.1021/es702493v

Zhai, H., Frey, H. C., Rouphail, N. M., Gonçalves, G. A., & Farias, T. L. (2008). Impact of Alternative Vehicle Technologies on Measured Vehicle Emissions. Transportation Land Use, Planning, and Air Quality, 320. https://doi.org/10.1061/40960(320)38

Zhai, H., Frey, H. C., Rouphail, N. M., Gon?alves, G. A., & Farias, T. L. (2008). Impact of alternative vehicle technologies on measured vehicle emissions. Transportation Land Use, Planning, and Air Quality - Proceedings of the 2007 Transportation Land Use, Planning, and Air Quality Conference, 320, 408–414. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-57549103716&partnerID=MN8TOARS

Frey, H. C., Rouphail, N. M., & Zhai, H. (2008). Link-based emission factors for heavy-duty diesel trucks based on real-world data. Transportation Research Record, (2058), 23–32. https://doi.org/10.3141/2058-04

Frey, H. C., Kuo, P.-Y., & Villa, C. (2008). Measurement and modeling of fuel use and exhaust emissions from idling Long-haul freight truck and auxiliary power unit engines. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3060–3064. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-70449497001&partnerID=MN8TOARS

Frey, H. C., Kuo, P.-Y., & Villa, C. (2008). Methodology for characterization of long-haul truck idling activity under real-world conditions. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 13(8), 516–523. https://doi.org/10.1016/j.trd.2008.09.010

Frey, H. C., Rasdorf, W., Kim, K., Pang, S.-H., Lewis, P., & Abolhassani, S. (2008). Real-world duty cycles and utilization for construction equipment in North Carolina. In Technical Report- Not held in TRLN member libraries. Raleigh, N.C.:  North Carolina Department of Transportation.

Abolhasani, S., Frey, H. C., Kim, K., Rasdorf, W., Lewis, P., & Pang, S.-H. (2008). Real-world in-use activity, fuel use, and emissions for nonroad construction vehicles: A case study for excavators. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 58(8), 1033–1046. https://doi.org/10.3155/1047-3289.58.8.1033

Frey, H. C., Pang, S.-H., & Kim, K. (2008). Vehicle-specific emissions modeling for non-road construction vehicles based upon real-world measurements. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 2743–2749. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-70449336768&partnerID=MN8TOARS

Frey, H. C. (2008). What is uncertainty analysis and how can it be performed? Toxicology Letters, 180, 3. https://doi.org/10.1016/j.toxlet.2008.06.016

Frey, H. C., Rouphail, N. M., Zhai, H., Farias, T. L., & Goncalves, G. A. (2007). Comparing real-world fuel consumption for diesel- and hydrogen-fueled transit buses and implication for emissions. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 12(4), 281–291. https://doi.org/10.1016/j.trd.2007.03.003

Zhai, H., Frey, H. C., Rouphail, N. M., Gonçalves, G. A., & Farias, T. L. (2007). Fuel consumption and emissions comparisons between ethanol 85 and gasoline fuels for flexible fuel vehicles. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3104–3108. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-44649111256&partnerID=MN8TOARS

Frey, H. C., Rasdorf, W., Kim, K., Pang, S.-H., Lewis, P., & Abolhassani, S. (2007). Life cycle inventory and impact analysis framework for nonroad construction vehicles and equipment based upon in-use measurements. In Technical Report- Not held in TRLN member libraries. Raleigh, N.C.:  National Science Foundation.

Frey, H. C., Rasdorf, W., Pang, S. H., Kim, K., Abolhasani, S., & Lewis, P. (2007). Methodology for activity, fuel use, and emissions data collection and analysis for nonroad construction equipment. Proceedings of the Air and Waste Management Association Annual Conference. Pittsburgh, PA: AWMA.

Frey, H. C., Rasdorf, W., Pang, S.-H., Kim, K., Abolhasani, S., & Lewis, P. (2007). Methodology for activity, fuel use, and emissions data collection and analysis for nonroad construction equipment. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3124–3128. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-44649103903&partnerID=MN8TOARS

Frey, H. C., Rasdorf, W., Pang, S., Kim, K., & Lewis, P. (2007). Methods for measurement and analysis of in-use emissions of nonroad construction equipment. Proceedings of the EPA Emissions Inventory Conference. Raleigh, NC: EPA.

Frey, H. C., & Kuo, P.-Y. (2007). Potential best practices for reducing greenhouse gas (GHG) emissions in freight transportation. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 5, 3099–3103. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-44649095696&partnerID=MN8TOARS

Vicari, A. S., Mokhtari, A., Morales, R. A., Jaykus, L.-A., Frey, H. C., Slenning, B. D., & Cowen, P. (2007). Second-order modeling of variability and uncertainty in microbial hazard characterization. JOURNAL OF FOOD PROTECTION, 70(2), 363–372. https://doi.org/10.4315/0362-028X-70.2.363

Zhu, Y., & Frey, H. C. (2007). Simplified performance model of gas turbine combined cycle systems. Journal of Energy Engineering, 133(2), 82–90. https://doi.org/10.1061/(asce)0733-9402(2007)133:2(82)

Frey, H. C., & Zhang, K. (2007). Spatial and temporal analysis of real-world empirical fuel use and emissions. 100th Annual Conference and Exhibition of the Air and Waste Management Association 2007, ACE 2007, 3, 2097–2102. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-44649198655&partnerID=MN8TOARS

Miller, C. A., Hidy, G., Hales, J., Kolb, C. E., Werner, A. S., Haneke, B., … Mobley, J. D. (2006). [Review of Air emission inventories in North America: A critical assessment]. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 56(8), 1115–1129. https://doi.org/10.1080/10473289.2006.10464540

Mokhtari, A., Frey, H. C., & Jaykus, L. A. (2006). Application of classification and regression trees for sensitivity analysis of the Escherichia coli O157 : H7 food safety process risk model. JOURNAL OF FOOD PROTECTION, 69(3), 609–618. https://doi.org/10.4315/0362-028X-69.3.609

Zietsman, J., Perkinson, D. G., Frey, H. C., & Wieters, K. M. (2006). Emissions comparison between dirt roads and paved roads using portable emissions measurement systems. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 6, 3421–3439. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-33847791632&partnerID=MN8TOARS

Mokhtari, A., Frey, H. C., & Zheng, J. (2006). Evaluation and recommendation of sensitivity analysis methods for application to Stochastic Human Exposure and Dose Simulation models. JOURNAL OF EXPOSURE SCIENCE AND ENVIRONMENTAL EPIDEMIOLOGY, 16(6), 491–506. https://doi.org/10.1038/sj.jes.7500472

Silva, C. M., Farias, T. L., Frey, H. C., & Rouphail, N. M. (2006). Evaluation of numerical models for simulation of real-world hot-stabilized fuel consumption and emissions of gasoline light-duty vehicles. TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, 11(5), 377–385. https://doi.org/10.1016/j.trd.2006.07.004

Mokhtari, A., & Frey, H. C. (2006). Evaluation of sampling-based methods for sensitivity analysis: Case study for the E-Coli food safety process risk model. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 12(6), 1128–1152. https://doi.org/10.1080/10807030600977251

Frey, H. C., & Zhu, Y. H. (2006). Improved system integration for integrated gasification combined cycle (IGCC) systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 40(5), 1693–1699. https://doi.org/10.1021/es0515598

Kim, K., Abolhasani, S., Pang, S.-H., & Frey, H. C. (2006). Real-world data collection procedure for non-road construction equipment: Problems, solutions, and data quality assurance. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3, 1935–1939. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-33847776263&partnerID=MN8TOARS

Zhang, K., & Frey, H. C. (2006). Road grade estimation for on-road vehicle emissions modeling using light detection and ranging data. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 56(6), 777–788. https://doi.org/10.1080/10473289.2006.10464500

Christopher Frey, H., Rouphail, N. M., & Zhai, H. (2006). Speed- And facility-specific emission estimates for on-road light-duty vehicles on the basis of real-world speed profiles. Transportation Research Record, (1987), 128–137. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-33947608832&partnerID=MN8TOARS

Zhu, Y., & Frey, H. C. (2006). Uncertainty analysis of integrated gasification combined cycle systems based on frame 7H versus 7F gas turbines. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 56(12), 1649–1661. https://doi.org/10.1080/10473289.2006.10464570

Zhao, Y., & Frey, H. C. (2006). Uncertainty for data with non-detects: Air toxic emissions from combustion. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 12(6), 1171–1191. https://doi.org/10.1080/10807030600977178

Frey, H. C., & Kim, K. (2005). In-use emissions of heavy duty diesel dump trucks on petroleum diesel and B20 biodiesel fuels. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2005. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-33646469610&partnerID=MN8TOARS

Zheng, J. Y., & Frey, H. C. (2005). Quantitative analysis of variability and uncertainty with known measurement error: Methodology and case study. RISK ANALYSIS, 25(3), 663–675. https://doi.org/10.1111/j.1539-6924.2005.00620.x

Mokhtari, A., & Frey, H. C. (2005). Recommended practice regarding selection of sensitivity analysis methods applied to microbial food safety process risk models. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 11(3), 591–605. https://doi.org/10.1080/10807030590949672

Zhang, K., & Frey, C. (2005). Road grade estimation for on-road vehicle emissions modeling using lidar data. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 2005. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-33646469896&partnerID=MN8TOARS

Mokhtari, A., & Frey, H. C. (2005). Sensitivity analysis of a two-dimensional probabilistic risk assessment model using analysis of variance. RISK ANALYSIS, 25(6), 1511–1529. https://doi.org/10.1111/j.1539-6924.2005.00679.x

Hanna, S. R., Heinold, D., Paine, R., Frey, H. C., Baker, D., Karp, R., & Feldman, H. (2004). A Monte Carlo study of the uncertainties in predictions by ISC3ST and AERMOD of annual average benzene and 1,3-butadiene concentrations around the Houston Ship Channel. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3145–3157. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-21944432040&partnerID=MN8TOARS

Hanna, A. F., Vukovich, J. M., Arunachalam, S., Loughlin, D., Frey, H. C., & Isakov, V. (2004). Assessment of uncertainty in benzene concentration estimates in the Houston, TX, area. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA, 3129–3143. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-21944435254&partnerID=MN8TOARS

Patil, SR, & Frey, H. C. (2004). Comparison of sensitivity analysis methods based on applications to a food safety risk assessment model. RISK ANALYSIS, 24(3), 573–585. https://doi.org/10.1111/j.0272-4332.2004.00460.x

Zhao, Y. C., & Frey, H. C. (2004). Development of probabilistic emission inventories of air toxics for Jacksonville, Florida. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 54(11), 1405–1421. https://doi.org/10.1080/10473289.2004.10471002

Zhao, Y., & Frey, H. C. (2004). Development of probabilistic emission inventory of air toxics for Jacksonville, Florida. Proceedings of the Air and Waste Management Association's Annual Conference and Exhibition, AWMA. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-21944442584&partnerID=MN8TOARS

Zhao, Y., & Christopher Frey, H. (2004). Development of probabilistic emission inventory of air toxics for jacksonville, Florida. Proceedings of the Air and Waste Management Association's Annual Meeting and Exhibition, 3101–3114. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-18944389363&partnerID=MN8TOARS

Chen, J. J., & Frey, H. C. (2004). Optimization under variability and uncertainty: A case study for NOx emissions control for a gasification system. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 38(24), 6741–6747. https://doi.org/10.1021/es0351037

Abdel-Aziz, A., & Frey, H. C. (2004). Propagation of uncertainty in hourly utility NOx emissions through a photochemical grid air quality model: A case study for the Charlotte, NC, modeling domain. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 38(7), 2153–2160. https://doi.org/10.1021/es034062b

Unal, A., Frey, H. C., & Rouphail, N. M. (2004). Quantification of highway vehicle emissions hot spots based upon on-board measurements. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 54(2), 130–140. https://doi.org/10.1080/10473289.2004.10470888

Frey, H. C., & Zhao, Y. C. (2004). Quantification of variability and uncertainty for air toxic emission inventories with censored emission factor data. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 38(22), 6094–6100. https://doi.org/10.1021/es035096m

Zhao, Y. C., & Frey, H. C. (2004). Quantification of variability and uncertainty for censored data sets and application to air toxic emission factors. RISK ANALYSIS, 24(4), 1019–1034. https://doi.org/10.1111/j.0272-4332.2004.00504.x

Zheng, J. Y., & Frey, H. C. (2004). Quantification of variability and uncertainty using mixture distributions: Evaluation of sample size, mixing weights, and separation between components. RISK ANALYSIS, 24(3), 553–571. https://doi.org/10.1111/j.0272-4332.2004.00459.x

Abdel-Aziz, A., & Frey, H. C. (2003). Development of hourly probabilistic utility NOx emission inventories using time series techniques: Part I - univariate approach. ATMOSPHERIC ENVIRONMENT, 37(38), 5379–5389. https://doi.org/10.1016/j.atmosenv.2003.09.007

Abdel-Aziz, A., & Frey, H. C. (2003). Development of hourly probabilistic utility NOx emission inventories using time series techniques: Part II - multivariate approach. ATMOSPHERIC ENVIRONMENT, 37(38), 5391–5401. https://doi.org/10.1016/j.atmosenv.2003.09.008

Unal, A., Rouphail, N. M., & Frey, H. C. (2003). Effect of arterial signalization and level of service on measured vehicle emissions. In Energy, air quality, and fuels 2003 (pp. 47–56). Washington, DC: Transportation Research Board.

Unal, A., Rouphail, N. M., & Frey, C. (2003). Effect of arterial signalization and level of service on measured vehicle emissions. Transportation Research Record, (1842), 47–56. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-1542316140&partnerID=MN8TOARS

Christopher Frey, H., & Small, M. J. (2003). Integrated environmental assessment, Part I: Estimating emissions. Journal of Industrial Ecology, 7(1), 9–11. https://doi.org/10.1162/108819803766729159

Frey, H. C., & Li, S. (2003). Methods for quantifying variability and uncertainty in AP-42 emission factors: Case studies for natural gas-fueled engines. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 53(12), 1436–1447. https://doi.org/10.1080/10473289.2003.10466317

Frey, H. C., Unal, A., Rouphail, N. M., & Colyar, J. D. (2003). On-road measurement of vehicle tailpipe emissions using a portable instrument. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 53(8), 992–1002. https://doi.org/10.1080/10473289.2003.10466245

Frey, H. C., & Bammi, S. (2003). Probabilistic nonroad mobile source emission factors. Journal of Environmental Engineering, 129(2), 162–168. https://doi.org/10.1061/(asce)0733-9372(2003)129:2(162)

Abdel-Aziz, A., & Frey, H. C. (2003). Quantification of hourly variability in NOx emissions for baseload coal-fired power plants. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 53(11), 1401–1411. https://doi.org/10.1080/10473289.2003.10466298

Frey, H. C., & Patil, S. R. (2002). Identification and review of sensitivity analysis methods. Risk Analysis, 22(3), 553–578. https://doi.org/10.1111/0272-4332.00039

Frey, H. C. (2002). Introduction to special section on sensitivity analysis and summary of NCSU/USDA workshop on sensitivity analysis. RISK ANALYSIS, 22(3), 539–545. https://doi.org/10.1111/0272-4332.00037

Frey, H. C., & Zheng, J. Y. (2002). Probabilistic analysis of driving cycle-based highway vehicle emission factors. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 36(23), 5184–5191. https://doi.org/10.1021/es0114308

Frey, H. C., & Zheng, J. Y. (2002). Quantification of variability and uncertainty in air pollutant emission inventories: Method and case study for utility NOx emissions. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 52(9), 1083–1095. https://doi.org/10.1080/10473289.2002.10470837

Frey, H. C., & Bammi, S. (2002). Quantification of variability and uncertainty in lawn and garden equipment NOx and total hydrocarbon emission factors. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 52(4), 435–448. https://doi.org/10.1080/10473289.2002.10470792

Hanna, SR, Lu, Z. G., Frey, H. C., Wheeler, N., Vukovich, J., Arunachalam, S., … Hansen, D. A. (2001). Uncertainties in predicted ozone concentrations due to input uncertainties for the UAM-V photochemical grid model applied to the July 1995 OTAG domain. ATMOSPHERIC ENVIRONMENT, 35(5), 891–903. https://doi.org/10.1016/S1352-2310(00)00367-8

Frey, H. C., & Burmaster, D. E. (1999). Methods for characterizing variability and uncertainty: Comparison of bootstrap simulation and likelihood-based approaches. Risk Analysis, 19(1), 109–130. https://doi.org/10.1111/j.1539-6924.1999.tb00393.x

Frey, H. C., & Burmaster, D. E. (1999). Methods for characterizing variability and uncertainty: Comparison of bootstrap simulation and likelihood-based approaches. Risk Analysis, 19(1), 109–130. https://doi.org/10.1023/A:1006962412150

Frey, H. C., & Rhodes, D. S. (1998). Characterization and simulation of uncertain frequency distributions: Effects of distribution choice, variability, uncertainty, and parameter dependence. HUMAN AND ECOLOGICAL RISK ASSESSMENT, 4(2), 423–468. https://doi.org/10.1080/10807039891284406

Frey, H. C., & Bharvirkar, R. (1998). Desktop modeling of the performance, emissions, and cost of gasification systems. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition, 91(1998 June). Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0032274276&partnerID=MN8TOARS

Frey, H. C. (1998). Methods for quantitative analysis of variability and uncertainty in hazardous air pollutant emissions. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition, 91(1998 June). Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-18344405017&partnerID=MN8TOARS

Frey, H. C. (1998). Quantitative analysis of variability and uncertainty in energy and environmental systems. In Uncertainty modeling and analysis in civil engineering (pp. 381–423). Boca Raton: CRC Press.

Frey, H. C. (1997). Bootstrap methods for quantitative analysis of variability and uncertainty in exposure and risk assessment. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0031344095&partnerID=MN8TOARS

Rubin, E. S., Kalagnanam, JR, Frey, H. C., & Berkenpas, M. B. (1997). Integrated environmental control modeling of coal-fired power systems. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, 47(11), 1180–1188. https://doi.org/10.1080/10473289.1997.10464063

Frey, H. C., & Iwanski, Z. (1997). Methods for characterizing and managing technological risks in advanced power generation systems: Application to gasification repowering in Poland. Proceedings of Gasification Technologies Conference, Electric Power Research lnstitute, Palo Alto, CA. October 1997, (1997 Oct.).

Agarwal, P., & Frey, H. C. (1997). Modeling and evaluation of externally fired combined cycle using ASPEN. Journal of Energy Engineering, 123(3), 69–87. https://doi.org/10.1061/(ASCE)0733-9402(1997)123:3(69)

Agrawal, P., & Frey, H. C. (1997). Modeling and evaluation of externally fired combined cycle using ASPEN. Journal of Energy Engineering, 123(3), 69–86. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-6144248166&partnerID=MN8TOARS

Diwekar, U. M., Rubin, E. S., & Frey, H. C. (1997). Optimal design of advanced power systems under uncertainty. ENERGY CONVERSION AND MANAGEMENT, Vol. 38, pp. 1725–1735. https://doi.org/10.1016/S0196-8904(96)00184-7

Diwekar, U. M., Rubin, E. S., & Frey, H. C. (1997). Optimal design of advanced power systems under uncertainty. Energy Conversion and Management, 38(15-17), 1725–1735. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0031259174&partnerID=MN8TOARS

Kini, M. D., & Frey, H. C. (1997). Probabilistic evaluation of mobile source air pollution. Volume I, Probabilistic modeling of exhaust emissions from light duty gasoline vehicles. Raleigh, NC: North Carolina State University for Center for Transportation and the Environment.

Frey, H. C., & Iwanski, Z. (1997). Probabilistic methodology for risk assessment of new energy technologies and application to gasification repowering for an oil refinery in Poland. In G. Manfrida & N. Lior (Eds.), Florence World Energy Research Symposium (1997): FLOWERS ''97: Florence World Energy Symposium (Vol. 39, pp. 267–274). Padova, Italy: SGEditorial.

Frey, H. C. (1997). Quantification of uncertainty in remotesensing-based school bus CO and hydrocarbon emission factors. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0031354445&partnerID=MN8TOARS

Rhodes, D. S., & Frey, H. C. (1997). Quantification of variability and uncertainty in AP-42 emission factors using bootstrap simulation. Emission inventory: Planning for the future, proceedings of a specialty conference, October 28-30, 1997, Research Triangle Park, NC, (1997 Oct.). Pittsburgh, Pa.: Air & Waste Management Association.

Frey, H. C., & Rubin, E. S. (1997). Uncertainty evaluation in capital cost projection. In Encyclopedia of chemical processing and design, Vol. 59 (Vol. 59, pp. 480–494). New York: Marcel Dekker.

Frey, H. C. (1997). Variability and uncertainty in highway vehicle emission factors. Emission inventory: Planning for the future, proceedings of a specialty conference, October 28-30, 1997, Research Triangle Park, NC, (1997 Oct.). Pittsburgh, Pa.: Air & Waste Management Association.

Frey, H. C., & Rhodes, D. S. (1996). Characterizing, simulating, and analyzing variability and uncertainty: An illustration of methods using an air toxics emissions example. Human and Ecological Risk Assessment (HERA), 2(4), 762–797. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-21444446390&partnerID=MN8TOARS

Frey, H. C. (1996). Comparison of classroom and video-based instruction: a case study for a graduate-level air pollution control course. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0030313917&partnerID=MN8TOARS

Tran, L. K., & Frey, H. C. (1996). Methods for evaluating the costs of utility NOx control technologies. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0030315356&partnerID=MN8TOARS

Diwekar, U. M., Rubin, E. S., & Frey, H. C. (1996). Optimization of environmental control system design for an IGCC power plant. Proceedings of the American Power Conference, 1, 58–63. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0029706671&partnerID=MN8TOARS

Frey, H. C., & Agarwal, P. (1996). Probabilistic analysis and optimization of new power generation technologies: a case study for the externally-fired combined cycle. Proceedings of the American Power Conference, 1, 52–57. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0029707721&partnerID=MN8TOARS

Frey, H. C., & Agarwal, P. (1996). Probabilistic modeling and optimization of clean coal technologies: case studies of the externally-fired combined cycle. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0030314477&partnerID=MN8TOARS

Frey, H. C., Kini, M. D., Ranjithan, S. R., & Fu, S.-Y. (1996). Uncertainty, bias, and variability in emission factors for light duty gasoline vehicles. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-17544390686&partnerID=MN8TOARS

Shih, J.-S., & Frey, H. C. (1995). Coal blending optimization under uncertainty. European Journal of Operational Research, 83(3), 452–465. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0029328154&partnerID=MN8TOARS

Frey, H. C. (1995). Engineering-economic evaluation of SCR NO<sub>x</sub> control systems for coal-fired power plants. Proceedings of the American Power Conference, 57-2, 1583–1588. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0029232725&partnerID=MN8TOARS

Frey, H. C., Rubin, E. S., & Diwekar, U. M. (1994). Modeling uncertainties in advanced technologies: Application to a coal gasification system with hot-gas cleanup. Energy, 19(4), 449–463. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0028413599&partnerID=MN8TOARS

Frey, H. C., & Rubin, E. S. (1992). Evaluate uncertainties in advanced process technologies. Chemical Engineering Progress, 88(5), 63–70. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0026855415&partnerID=MN8TOARS

Frey, H. C., & Rubin, E. S. (1992). Evaluation method for advanced acid rain compliance technology. Journal of Energy Engineering, 118(1), 38–55. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0026853964&partnerID=MN8TOARS

Frey, H. C., & Rubin, E. S. (1992). Evaluation of Advanced Coal Gasification Combined-Cycle Systems under Uncertainty. Industrial and Engineering Chemistry Research, 31(5), 1299–1307. https://doi.org/10.1021/ie00005a010

Diwekar, U. M., Frey, H. C., & Rubin, E. S. (1992). Synthesizing Optimal Flowsheets: Applications to IGCC System Environmental Control. Industrial and Engineering Chemistry Research, 31(8), 1927–1936. https://doi.org/10.1021/ie00008a014

Frey, H. C., & Rubin, E. S. (1991). Evaluating advanced technologies for acid rain compliance. Energy in the 90's, 172–178. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0025843790&partnerID=MN8TOARS

Frey, H. C., & Rubin, E. S. (1991). Probabilistic Evaluation of Advanced So<sub>2</sub>/No<sub>X</sub> Control Technology. Journal of the Air and Waste Management Association, 41(12), 1585–1593. https://doi.org/10.1080/10473289.1991.10466954

Rubin, E. S., Frey, H. C., & Diwekar, U. M. (1991). Probabilistic modeling of the performance and economics of IGCC systems. American Society of Mechanical Engineers, Environmental Control Division Publication, EC, 2, 59–66. Retrieved from http://www.scopus.com/inward/record.url?eid=2-s2.0-0026400326&partnerID=MN8TOARS

Rubin, E. S., Salmento, J. S., & Frey, H. C. (1988). Cost-Effective emission controls for coal-fired power plants. Chemical Engineering Communications, 74(1), 155–167. https://doi.org/10.1080/00986448808940456