@article{jia_yang_xu_snyder_patrick_kumar_zhang_xu_2023, title={Polymer-derived SiOC reinforced with core-shell nanophase structure of ZrB2/ZrO2 for excellent and stable high-temperature microwave absorption (up to 900 degrees C)}, volume={13}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-023-27541-3}, abstractNote={Abstract Microwave absorbing materials for high-temperature harsh environments are highly desirable for aerodynamically heated parts and engine combustion induced hot spots of aircrafts. This study reports ceramic composites with excellent and stable high-temperature microwave absorption in air, which are made of polymer-derived SiOC reinforced with core–shell nanophase structure of ZrB 2 /ZrO 2 . The fabricated ceramic composites have a crystallized t-ZrO 2 interface between ZrB 2 and SiOC domains. The ceramic composites exhibit stable dielectric properties, which are relatively insensitive to temperature change from room temperature to 900 °C. The return loss exceeds − 10 dB, especially between 28 and 40 GHz, at the elevated temperatures. The stable high-temperature electromagnetic (EM) absorption properties are attributed to the stable dielectric and electrical properties induced by the core–shell nanophase structure of ZrB 2 /ZrO 2 . Crystallized t-ZrO 2 serve as nanoscale dielectric interfaces between ZrB 2 and SiOC, which are favorable for EM wave introduction for enhancing polarization loss and absorption. Existence of t-ZrO 2 interface also changes the temperature-dependent DC conductivity of ZrB 2 /SiOC ceramic composites when compared to that of ZrB 2 and SiOC alone. Experimental results from thermomechanical, jet flow, thermal shock, and water vapor tests demonstrate that the developed ceramic composites have high stability in harsh environments, and can be used as high-temperature wide-band microwave absorbing structural materials.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Jia, Yujun and Yang, Ni and Xu, Shaofan and Snyder, Alexander D. D. and Patrick, Jason F. F. and Kumar, Rajan and Zhang, Dajie and Xu, Chengying}, year={2023}, month={Jan} }
 @article{liu_liu_wu_zhou_liang_liu_duan_gu_xu_travitzky_et al._2023, title={Structural Electromagnetic Absorber Based on MoS2/PyC-Al2O3 Ceramic Metamaterials}, ISSN={["1613-6829"]}, DOI={10.1002/smll.202300664}, abstractNote={Limited by the types of suitable absorbents as well as the challenges in engineering the nanostructures (e.g., defects, dipoles, and hetero-interface) using state-of-the-art additive manufacturing (AM) techniques, the electromagnetic (EM) wave absorption performance of the current ceramic-based materials is still not satisfying. Moreover, because of the high residual porosity and the possible formation of cracks during sintering or pyrolysis, AM-formed ceramic components may in many cases exhibit low mechanical strength. In this work, semiconductive MoS2 and conductive PyC modified Al2 O3 (MoS2 /PyC-Al2 O3 ) ceramic-based structural EM metamaterials are developed by innovatively harnessing AM, precursor infiltration and pyrolysis (PIP), and hydrothermal methods. Three different meta-structures are successfully created, and the ceramic-based nanocomposite benefit from its optimization of EM parameters. Ultra-broad effective absorption bandwidth (EAB) of 35 GHz is achieved by establishment of multi-loss mechanism via nanostructure engineering and fabrication of meta-structures via AM. Due to the strengthening by the PyC phase, the bending strength of the resulting ceramics can reach ≈327 MPa, which is the highest value measured on 3D-printed ceramics of this type that has been reported so far. For the first time, the positive effect deriving from the engineering of the microscopic nano/microstructure and of the macroscopic meta-structure of the absorber on the permittivity and EM absorption performance is proposed. Integration of outstanding mechanical strength and ultra-broad EAB is innovatively realized through a multi-scale design route. This work provides new insights for the design of advanced ceramic-based metamaterials with outstanding performance under extreme environment.}, journal={SMALL}, author={Liu, Xingmin and Liu, Heqiang and Wu, Hongjing and Zhou, Qian and Liang, Hongsheng and Liu, Guoqiang and Duan, Wenyan and Gu, Yue and Xu, Chengying and Travitzky, Nahum and et al.}, year={2023}, month={Apr} }
 @article{yang_zhang_reynolds_kumah_xu_2023, title={The Role of Carbon Content: A Comparison of the Nickel Particle Size and Magnetic Property of Nickel/Polysiloxane-Derived Silicon Oxycarbide}, volume={1}, ISSN={["1527-2648"]}, url={https://doi.org/10.1002/adem.202201453}, DOI={10.1002/adem.202201453}, journal={ADVANCED ENGINEERING MATERIALS}, author={Yang, Ni and Zhang, Xuanyi and Reynolds, Lewis and Kumah, Divine and Xu, Chengying}, year={2023}, month={Jan} }
 @misc{kenion_yang_xu_2022, title={Dielectric and mechanical properties of hypersonic radome materials and metamaterial design: A review}, volume={42}, ISSN={["1873-619X"]}, DOI={10.1016/j.jeurceramsoc.2021.10.006}, abstractNote={This review paper examines ten current ceramic radome materials under research and development and provides a comprehensive overview of available high temperature and high frequency data from literature. An examination of metamaterials for radio-frequency transparent radomes is given and our preliminary experimental results of a high-temperature metamaterial design are presented. The next-generation hypersonic vehicles’ radome temperatures will exceed 1000℃ and speeds will exceed Mach 5. An ideal radome material will have a high flexural strength, low dielectric constant and loss tangent, and high resistance to thermal shock and corrosion. The microstructural effect on the dielectric and mechanical properties and the effects of environmental factors such as rain are discussed. The impact of metamaterial structure on key radome factors such as boresight error, gain, and polarization is examined. After examining the associated benefits with the use of metamaterials, our preliminary results for a potential high-temperature metamaterial design are presented.}, number={1}, journal={JOURNAL OF THE EUROPEAN CERAMIC SOCIETY}, author={Kenion, Taylor and Yang, Ni and Xu, Chengying}, year={2022}, month={Jan}, pages={1–17} }
 @article{pasagada_yang_xu_2022, title={Electron beam sintering (EBS) process for Ultra-High Temperature Ceramics (UHTCs) and the comparison with traditional UHTC sintering and metal Electron Beam Melting (EBM) processes}, volume={48}, ISSN={["1873-3956"]}, DOI={10.1016/j.ceramint.2021.12.229}, abstractNote={Ultra-high temperature ceramics (UHTCs) are refractory materials with unusual properties making them strong contenders for applications involving adverse and chemically aggressive environments. This paper presents an effort to process UHTCs using an additive manufacturing method, specifically Electron Beam Sintering (EBS) - adoption of the Electron Beam powder-bed fusion (PBF) process. Such a process shows that the processing and consolidation phenomenon of UHTCs are different from what is observed in the traditional sintering process of UHTCs and Electron Beam Melting (EBM) of typical metals or alloys. In this article, the EBS process of UHTCs is studied. The differences between EBS and the two aforementioned traditional processing methods are analyzed. The scientific hypotheses have been backed by experimental results on a ZrB2 – 30 vol% ZrSi2 UHTC mixture using an electron beam via Liquid Phase Sintering (LPS) theory. Efforts to develop processing conditions to fabricate dense and defect-free UHTC components are explored with the help of finite element (FE) simulations. Characterization of the EBS processed samples using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD) revealed unique needle-like patterned grains of ZrB2 in a ZrSi2 matrix. Our findings demonstrate the feasibility of the EBS process to produce dense layers of UHTCs for coatings, potential three-dimensional, as well as complex-shaped applications.}, number={7}, journal={CERAMICS INTERNATIONAL}, author={Pasagada, Venkata Keerti Vardhan and Yang, Ni and Xu, Chengying}, year={2022}, month={Apr}, pages={10174–10186} }
 @article{yang_xu_xu_2022, title={Highly electromagnetic transparent ceramic composite made of boron nitride nanotubes and silicon oxynitride via perhydropolysilazane infiltration method}, volume={12}, ISSN={["2045-2322"]}, DOI={10.1038/s41598-022-18563-4}, abstractNote={With the rapid development of electromagnetic (EM) wave circuit devices, high-performance wave-transparent materials with various functions have attracted great attention. Ceramic material is a promising candidate to be applied in harsh environments because of its chemical and corrosion resistance. In this work, a polymer-derived route was adopted to synthesize ceramic composite at room temperature. The composite is made of perhydropolysilazane-derived SiON ceramic and reinforced with boron nitride nanotubes (BNNTs) sheets. With the addition of SiON ceramic materials, the resultant sample showed an excellent hydrophobicity with a contact angle of 135-146.9°. More importantly, superior thermal stability at 1600 °C in the oxygen-containing atmosphere was observed for the fabricated SiON/BNNTs sample, without any shape change. The electromagnetic transparency of the SiON/BNNTs was studied through the waveguide method. The prepared SiON/BNNTs sample has an average real permittivity between 1.52 and 1.55 and an average loss tangent value in the range of 0.0074-0.0266, at the frequency range of 26.5-40 GHz. The effect of thickness on the wave transparency of SiON/BNNTs samples is also discussed. To summarize the aforementioned superior characterization and measurement results, the presented SiON/BNNTs material system has a great potential to be used as EM transparent materials in harsh conditions.}, number={1}, journal={SCIENTIFIC REPORTS}, author={Yang, Ni and Xu, Shaofan and Xu, Chengying}, year={2022}, month={Aug} }
 @article{yang_xu_zhang_xu_2022, title={Super-Wideband Electromagnetic Absorbing TiC/SiOC Ceramic/Glass Composites Derived from Polysiloxane and Titanium Isopropoxide with Low Thickness (<1 mm)}, ISSN={["1527-2648"]}, DOI={10.1002/adem.202201508}, journal={ADVANCED ENGINEERING MATERIALS}, author={Yang, Ni and Xu, Shaofan and Zhang, Dajie and Xu, Chengying}, year={2022}, month={Dec} }
 @article{kulkarni_xu_2021, title={A Deep Learning Approach in Optical Inspection to Detect Hidden Hardware Trojans and Secure Cybersecurity in Electronics Manufacturing Supply Chains}, volume={7}, ISSN={["2297-3079"]}, DOI={10.3389/fmech.2021.709924}, abstractNote={Deep learning methods have been extensively studied and have been proven to be very useful in multiple fields of technology. This paper presents a deep learning approach to optically detect hidden hardware trojans in the manufacturing and assembly phase of printed circuit boards to secure electronic supply chains. Trojans can serve as backdoors of accessing on chip data, can potentially alter functioning and in some cases may even deny intended service of the chip. Apart from consumer electronics, printed circuit boards are used in mission critical applications like military and space equipment. Security compromise or data theft can have severe impact and thus demand research attention. The advantage of the proposed method is that it can be implemented in a manufacturing environment with limited training data. It can also provide better coverage in detection of hardware trojans over traditional methods. Image recognition algorithms need to have deeper penetration inside the training layers for recognizing physical variations of image patches. However, traditional network architectures often face vanishing gradient problem when the network layers are added. This hampers the overall accuracy of the network. To solve this a Residual network with multiple layers is used in this article. The ResNet34 algorithm can identify manufacturing tolerances and can differentiate between a manufacturing defect and a hardware trojan. The ResNet operates on the fundamental principle of learning from the residual of the output of preceding layer. In the degradation issue, it is observed that, a shallower network performs better than deeper network. However, this is with the downside of lower accuracy. Thus, a skip connection is made to provide an alternative path for the gradient to skip forward the training of few layers and add in multiple repeating blocks to achieve higher accuracy and lower training times. Implementation of this method can bolster automated optical inspection setup used to detect manufacturing variances on a printed circuit board. The results show a 98.5% accuracy in optically detecting trojans by this method and can help cut down redundancy of physically testing each board. The research results also provide a new consideration of hardware trojan benchmarking and its effect on optical detection.}, journal={FRONTIERS IN MECHANICAL ENGINEERING-SWITZERLAND}, author={Kulkarni, Ameya and Xu, Chengying}, year={2021}, month={Jul} }
 @article{jia_mehta_li_chowdhury_horn_xu_2021, title={Additive manufacturing of ZrB2-ZrSi2 ultra-high temperature ceramic composites using an electron beam melting process}, volume={47}, ISSN={["1873-3956"]}, DOI={10.1016/j.ceramint.2020.09.082}, abstractNote={Owing to their high melting points and ability to resist extreme thermal stresses, ultra-high temperature ceramics (UHTCs) are important materials for critical applications such as hypersonic flights, space re-entry vehicles, and rocket engines. Traditional manufacturing processes restrict the freedom to manufacture UHTCs with complex geometries due to the limitations of die and mold designs. Electron beam melting (EBM) is an established powder-bed layer-by-layer additive manufacturing (AM) process for metal parts. In this research, an effort was made to evaluate the feasibility of EBM for the AM fabrication of UHTC-based materials, and to investigate the microstructures of the fabricated materials under different processing conditions. A mathematical model was developed to simulate and optimize the processing parameters for the fabrication of ZrB2-30 vol% ZrSi2 UHTC using EBM. The simulation results were compared with experimental observations. For EBM fabrication of ZrB2-30 vol% ZrSi2 composites, the optimal processing parameters are beam power of 500 W with scanning speeds of 500, 750, and 1000 mm/s, and beam power of 1000 W with scanning speed of 1000 mm/s. This study demonstrates the potential for additive manufacturing of UHTCs with complex geometries by the EBM technique.}, number={2}, journal={CERAMICS INTERNATIONAL}, author={Jia, Yujun and Mehta, Shashvat Tejaskumar and Li, Ryan and Chowdhury, Md Atiqur Rahman and Horn, Timothy and Xu, Chengying}, year={2021}, month={Jan}, pages={2397–2405} }
 @inbook{schrand_kolel-veetil_elston_neff_ajayi_xu_2021, title={Printable Materials for Additive Manufacturing in Harsh Earth and Space Environments}, ISBN={9781003131915}, booktitle={Nanotechnology in Space}, publisher={CRC Press - Taylor & Francis Group}, author={Schrand, A.M. and Kolel-Veetil, M. and Elston, E. and Neff, C. and Ajayi, T. and Xu, C.}, editor={Terranova, Maria Letizia and Tamburri, EmanuelaEditors}, year={2021} }
 @article{daniel_nguyen_chowdhury_xu_xu_2021, title={Temperature and Pressure Wireless Ceramic Sensor (Distance=0.5 Meter) for Extreme Environment Applications}, volume={21}, ISSN={["1424-8220"]}, DOI={10.3390/s21196648}, abstractNote={This paper presents a design for temperature and pressure wireless sensors made of polymer-derived ceramics for extreme environment applications. The wireless sensors were designed and fabricated with conductive carbon paste on an 18.24 mm diameter with 2.4 mm thickness polymer-derived ceramic silicon carbon nitride (PDC-SiCN) disk substrate for the temperature sensor and an 18 × 18 × 2.6 mm silicon carbide ceramic substrate for the pressure sensor. In the experiment, a horn antenna interrogated the patch antenna sensor on a standard muffle furnace and a Shimadzu AGS-J universal test machine (UTM) at a wireless sensing distance of 0.5 m. The monotonic relationship between the dielectric constant of the ceramic substrate and ambient temperature is the fundamental principle for wireless temperature sensing. The temperature measurement has been demonstrated from 600 °C to 900 °C. The result closely matches the thermocouple measurement with a mean absolute difference of 2.63 °C. For the pressure sensor, the patch antenna was designed to resonate at 4.7 GHz at the no-loading case. The sensing mechanism is based on the piezo-dielectric property of the silicon carbon nitride. The developed temperature/pressure sensing system provides a feasible solution for wireless measurement for extreme environment applications.}, number={19}, journal={SENSORS}, author={Daniel, Justin and Nguyen, Spencer and Chowdhury, Md Atiqur Rahman and Xu, Shaofan and Xu, Chengying}, year={2021}, month={Oct} }
 @article{jia_chowdhury_xu_2020, title={Complex impedance spectra of polymer-derived SiC annealed at ultrahigh temperature}, volume={103}, ISSN={["1551-2916"]}, DOI={10.1111/jace.17395}, abstractNote={This study reports the complex impedance and alternative current conductivity of polymer-derived ceramic SiC (PDC-SiC) annealed at ultrahigh temperatures. The PDC-SiC shows an inductive response when annealed at temperatures of 1700°C-1900°C due to the percolation of turbostratic carbon. The material returns to a capacitive response at an annealing temperature of 2000°C due to the dissolution of carbon into the SiC lattice. The electrical resistance of the carbon phase decreases with the increase in annealing temperature. These results provide new insights into the effects of processing temperature on microstructure evolution and electrical and dielectric property development of the PDC-SiC ceramic system.}, number={12}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Jia, Yujun and Chowdhury, Md Atiqur Rahman and Xu, Chengying}, year={2020}, month={Dec}, pages={6860–6868} }
 @article{jia_ajayi_xu_2020, title={Dielectric properties of polymer-derived ceramic reinforced with boron nitride nanotubes}, volume={103}, ISSN={["1551-2916"]}, DOI={10.1111/jace.17301}, abstractNote={The electrical and dielectric properties of boron nitride nanotubes (BNNTs) reinforced ceramic composites using the polymer-derived ceramic (PDC) processing route were investigated in this work. The electrical resistivity of the pristine PDC increases from 106 to 108 Ω m after the addition of BNNTs. When the BNNT loading was increased to 5 wt%, the average real relative permittivity of the PDC decreased from 2.94 to 2.80, while the quality factor (Q) of the PDC increased from 134.40 to 176.77. The BNNTs can increase the Q factor of the PDC due to the reduction in the porosity cause by the introduction of the BNNTs. Further increasing the BNNT content decreases the real relative permittivity of the nanocomposites and increases the Q factor at high frequency. The average real relative permittivity decreases to 2.29, while the average Q factor increases to 208.60 when the BNNT content is increased to 30 wt%. The dielectric loss after the addition of high fraction of BNNTs can be explained by the Lorentz resonance relaxation process. Results of this work showed that PDC-BNNT nanocomposites are satisfactory electromagnetic transparent materials when the BNNT fraction is less than 10 wt%.}, number={10}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={Jia, Yujun and Ajayi, Tosin D. and Xu, Chengying}, year={2020}, month={Sep}, pages={5731–5742} }
 @article{chowdhury_wang_jia_xu_2020, title={Electrical Conductivity and Structural Evolution of Polymer Derived SiC Ceramics Pyrolyzed From 1200°C to 1800°C}, volume={8}, ISSN={2166-0468 2166-0476}, url={http://dx.doi.org/10.1115/1.4046191}, DOI={10.1115/1.4046191}, abstractNote={Abstract Room temperature (RT) electrical conductivity and microstructure of polymer-derived SiC pyrolyzed at temperatures ranging from 1200 °C to 1800 °C were studied. We have shown that both free carbon content and pyrolysis temperature have significant effects on the DC conductivity of polymer derived ceramic (PDC) SiC. The RT DC conductivity of the PDC SiC increased gradually with increasing pyrolysis temperature, and it drastically increases 3 orders of magnitude after 1500 °C. This high electrical conductivity occurs due to the formation of a network of turbostratic carbon (percolative network). Below the percolation regime, hopping enables the electron movement from one carbon cluster site to another. Microstructural investigation with X-ray diffraction (XRD), Raman, and transmission electron microscopy (TEM) analysis showed that the crystal size of SiC increases with increasing pyrolysis temperature, and carbon clusters act as an inhibitor for grain growth at lower pyrolysis temperature. Upon dissociation of clusters, accelerated grain growth occurs and graphitization of carbon occurs along the grains.}, number={2}, journal={Journal of Micro and Nano-Manufacturing}, publisher={ASME International}, author={Chowdhury, Md Atiqur and Wang, Kewei and Jia, Yujun and Xu, Chengying}, year={2020}, month={Feb} }
 @article{jia_ajayi_wahls_ramakrishnan_ekkad_xu_2020, title={Multifunctional Ceramic Composite System for Simultaneous Thermal Protection and Electromagnetic Interference Shielding for Carbon Fiber-Reinforced Polymer Composites}, volume={12}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.0c17361}, abstractNote={Achieving a high electrical conductivity while maintaining a good thermal insulation is often contradictory in the material design for the goal of simultaneous thermal protection and electromagnetic interference shielding. The reason is that materials with a high electrical conductivity often pertain a high thermal conductivity. To address this challenge, this study reports a multifunctional ceramic composite system for carbon fiber-reinforced polymer composites. The fabricated multifunctional ceramic composite system has a multilayer structure. The polymer-derived SiCN ceramic reinforced with yttria-stabilized zirconia fibers serves as the thermal protection and impedance-matching layer, while the yttria-stabilized zirconia fiber-reinforced SiCN ceramic with carbon nanotubes provides the electromagnetic interference shielding. The thermal conductance of the multilayered ceramic composite is about 22.5% lower compared to that of the carbon fiber-reinforced polymer composites. The thermal insulation test during the steady-state condition shows that the hybrid composite can be used up to 300 °C while keeping the temperature reaching the surface of carbon fiber-reinforced polymer composites at around 167.8 °C. The flame test was used to characterize the thermal protection capability under transient conditions. The hybrid composite showed temperature differences of 72.9 and 280.7 °C during the low- and high-temperature settings, respectively. The average total shielding efficiency per thickness of the fabricated four-layered ceramic composite system was 21.45 dB/mm, which showed a high reflection-dominant electromagnetic interference shielding. The average total shielding efficiency per thickness of the eight-layered composite system was 16.57 dB/mm, revealing a high absorption-dominant electromagnetic interference shielding. Typical carbon fiber-reinforced polymer composites reveal a reflection-dominant electromagnetic interference shielding. The electrons can freely move in the percolated carbon nanotubes within the inner layers of the composite material, which provide the improved electromagnetic interference shielding ability. The movement of electrons was impeded by the top and bottom layers whose thermal conduction relies on the lattice vibrations, resulting in a satisfactory thermal insulation of the composite materials and impedance matching with the free space. Results of this study showed that materials with a good thermal insulation and electromagnetic interference shielding can be obtained simultaneously by confining the electron movement inside the materials and refraining their movement at the skin surface.}, number={52}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Jia, Yujun and Ajayi, Tosin D. and Wahls, Benjamin H. and Ramakrishnan, Kishore Ranganath and Ekkad, Srinath and Xu, Chengying}, year={2020}, month={Dec}, pages={58005–58017} }
 @article{jia_yang_wang_chowdhury_chen_su_nickerson_xu_2019, title={Aligned carbon nanotube/carbon (CNT/C) composites with exceptionally high electrical conductivity at elevated temperature to 400 degrees C}, volume={6}, ISSN={["2053-1591"]}, DOI={10.1088/2053-1591/ab4385}, number={11}, journal={MATERIALS RESEARCH EXPRESS}, author={Jia, Yujun and Yang, Jinshan and Wang, Kewei and Chowdhury, Md Atiqur Rahman and Chen, Banghao and Su, Yifeng and Nickerson, Bill C. and Xu, Chengying}, year={2019}, month={Sep} }
 @inproceedings{ajayi_kim_liu_nickerson_xu_2019, title={Multifunctional Hybrid Composite for Thermal Protection of Carbon Fiber Reinforced Polymers (CFRPS) in Aerospace Applications}, url={http://dx.doi.org/10.33599/nasampe/s.19.1367}, DOI={10.33599/nasampe/s.19.1367}, booktitle={SAMPE 2019 - Charlotte, NC}, publisher={SAMPE}, author={Ajayi, Tosin and Kim, Kyunghoon and Liu, Jun and Nickerson, Bill and Xu, Cheryl}, year={2019}, month={Apr} }
 @inproceedings{mousavinezhad_xu_2019, title={Science and Engineering Courses, Theory and Practice: An Example}, DOI={10.18260/1-2--33254}, booktitle={2019 ASEE Annual Conference & Exposition Proceedings}, author={Mousavinezhad, S. and Xu, C.}, year={2019} }
 @inproceedings{mousavinezhad_xu_tatar_2019, title={Teaching and Learning of Electrical and Computer Engineering Courses with High Mathematical Contents}, DOI={10.18260/1-2--33343}, booktitle={2019 ASEE Annual Conference & Exposition Proceedings}, author={Mousavinezhad, S. and Xu, C. and Tatar, E.}, year={2019} }
 @article{jia_chowdhury_zhang_xu_2019, title={Wide-Band Tunable Microwave-Absorbing Ceramic Composites Made of Polymer-Derived SiOC Ceramic and in Situ Partially Surface-Oxidized Ultra-High-Temperature Ceramics}, volume={11}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.9b16475}, abstractNote={Microwave-absorbing materials in a high-temperature harsh environment are highly desired for electronics and aerospace applications. This study reports a novel high-temperature microwave-absorbing ceramic composites made of polymer-derived SiOC ceramic and in situ partially surface-oxidized ultra-high-temperature ceramic (UHTC) ZrB2 nanoparticles. The fabricated composites with a normalized weight fraction of ZrB2 nanoparticles at 40% has a significantly wide microwave absorption bandwidth of 13.5 GHz (26.5-40 GHz) covering the entire Ka-band. This is attributed to the extensive nanointerfaces introduced in the composites, attenuation induced by the interference of electromagnetic wave, attenuation from the formed current loops, and the electronic conduction loss provided by the partially surface-oxidized ZrB2 nanoparticles. The minimum reflection coefficient (RC) was -29.30 dB at 29.47 GHz for a thickness of 1.26 mm for the composites with a normalized weight fraction of ZrB2 nanoparticles at 32.5%. The direct current (dc) conductivity of the nanocomposites showed a clear percolation phenomenon as the normalized weight fraction of ZrB2 nanoparticles increases to 30.49%. The results provide new insights in designing microwave-absorbing materials with a wide absorption frequency range and strong absorption loss for high-temperature harsh environment applications.}, number={49}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Jia, Yujun and Chowdhury, Md Atiqur Rahman and Zhang, Dajie and Xu, Chengying}, year={2019}, month={Dec}, pages={45862–45874} }
 @article{ju_yang_hao_daniel_morales_nguyen_andrei_liang_hellstrom_xu_2018, title={A hybrid ceramic-polymer composite fabricated by co-curing lay-up process for a strong bonding and enhanced transient thermal protection}, volume={44}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85045663642&partnerID=MN8TOARS}, DOI={10.1016/j.ceramint.2018.03.211}, abstractNote={Abstract A hybrid ceramic-polymer composite is fabricated by a co-curing lay-up process by combining a carbon nanotube (CNT) reinforced ceramic composite thin film with a carbon fiber reinforced polymer (CFRP) composite substrate. The ceramic nanocomposite thin film has good flexibility, thermal conductivity and high temperature tolerance. The polymer composite substrate is a carbon fiber reinforced bismaleimide composite that is widely used in aerospace and automotive industries. Finite element analysis (FEA) is used to investigate the maximum survival temperature with different thicknesses of the ceramic nanocomposite. The resultant hybrid composite shows good structural integrity and displays a pull-off bonding strength up to 8.3 MPa. In addition, thermal study illustrates that such a flexible CNT reinforced ceramic composite can effectively protect CFRP in an elevated temperature environment by delaying transient thermal conduction.}, number={10}, journal={Ceramics International}, author={Ju, L. and Yang, J. and Hao, A. and Daniel, J. and Morales, J. and Nguyen, S. and Andrei, P. and Liang, R. and Hellstrom, E. and Xu, C.}, year={2018}, pages={11497–11504} }
 @misc{xu_daniel_2018, title={Wireless Temperature Sensor for High Temperature Environments (up to 1000C) using RF Techniques with 0.5 meter Sensing Distance}, author={Xu, C. and Daniel, J.}, year={2018} }
 @book{xu_wang_2017, place={Pittsburgh, PA}, title={Effect of Processing Conditions on Electric and Dielectric Properties of Polymer-Derived SiC Ceramics}, publisher={Materials Science & Technology}, author={Xu, C. and Wang, K.}, year={2017} }
 @article{fan_wang_dong_wang_duan_mei_wang_zhang_xu_2017, title={Enhanced cyclic oxidation resistance through the self-healing of segmented cracks using nano-Al<inf>2</inf>O<inf>3</inf>/Ni-20 wt%Al particles in laser re-melted thermal barrier coatings}, volume={201}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85018757034&partnerID=MN8TOARS}, DOI={10.1016/j.matlet.2017.04.116}, abstractNote={Abstract This paper introduces a novel and effective self-healing method of segmented cracks in laser re-melted ZrO2-7 wt% Y2O3 thermal barrier coatings (TBCs). The method uses pressure sintering of nano-Al2O3/Ni-20 wt%Al particles at 1150 °C for 12 h. After treatment to facilitate self-healing, a very dense and metallurgically bonded nano-Al2O3 reinforced Ni-matrix sealed film formed in the segmented gaps. Cyclic oxidation results indicate that dense sealed films can effectively suppress the growth of thermally grown oxides (TGO) and prevent the formation of other brittle and fragile oxides (i.e., spinels) at the top coat/bond coat (TC/BC) interface. Using the pressure-sintering effect, any aluminums contained in the sealed particles or films becomes prone to diffusion into the TC/BC interface to facilitate the formation of a thin-continuous TGO during the initial oxidation. This results in a significantly enhanced anti-oxidation effect of laser re-melted TBCs.}, journal={Materials Letters}, author={Fan, Z. and Wang, K. and Dong, X. and Wang, R. and Duan, W. and Mei, X. and Wang, W. and Zhang, S. and Xu, C.}, year={2017}, pages={156–160} }
 @misc{macdonald_xu_2017, title={Metamaterial Enabling RF Transparency – Ceramic Composite Design for High Temperature Application}, author={Macdonald, J. and Xu, C.}, year={2017} }
 @misc{xu_peebles_2017, title={Non-Destructive Testing of Composite Materials at High Temperature (2000oC)}, author={Xu, C. and Peebles, J.}, year={2017} }
 @article{daniel_ju_yang_sun_gupta_schrand_xu_2017, title={Pearl-Chain Formation of Discontinuous Carbon Fiber Under Electrical Field}, volume={1}, DOI={10.3390/jmmp1020022}, abstractNote={The purpose of this paper is to develop a theoretical derivation on aligning discontinuous carbon fiber with an applied electric field, and prove the theory with experiment. A principle with regard to the occurrence of carbon fiber alignment is presented after an introduction of the electromechanical quantities of dielectrics. Based on this principle, an estimation of the polarizability tensor is employed to calculate the required electric field to achieve fiber alignment in liquid solution (e.g., water, resin, etc.). Individual carbon fiber is modeled as a polarizable dielectric cylinder in liquid resin and its motion under direct current (DC) electrical field is decomposed into a polarization effect and rotation effect. A value of 20.12 V/mm is required to align short carbon fibers (0.15 mm) long in liquid resin and is experimentally validated. Finally, an expression to include weight percentage as a means of controlling pearl-chain formation is derived to change the composite’s electrical conductivity.}, number={2}, journal={Journal of Manufacturing and Materials Processing}, publisher={MDPI AG}, author={Daniel, J. and Ju, L. and Yang, J. and Sun, X. and Gupta, N. and Schrand, A. and Xu, C.}, year={2017}, pages={22} }
 @article{davis_dabrow_ju_li_xu_huang_2017, title={Study of Chip Morphology and Chip Formation Mechanism during Machining of Magnesium-Based Metal Matrix Composites}, volume={139}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85025092741&partnerID=MN8TOARS}, DOI={10.1115/1.4037182}, abstractNote={Magnesium (Mg) and its alloys are among the lightest metallic structural materials, making them very attractive for use in the aerospace and automotive industries. Recently, Mg has been used in metal matrix composites (MMCs), demonstrating significant improvements in mechanical performance. However, the machinability of Mg-based MMCs is still largely elusive. In this study, Mg-based MMCs are machined using a wide range of cutting speeds in order to elucidate both the chip morphology and chip formation mechanism. Cutting speed is found to have the most significant influence on both the chip morphology and chip formation mechanism, with the propensity of discontinuous, particle-type chip formation increasing as the cutting speed increases. Saw-tooth chips are found to be the primary chip morphology at low cutting speeds (lower than 0.5 m/s), while discontinuous, particle-type chips prevail at high cutting speeds (higher than 1.0 m/s). Using in situ high-speed imaging, the formation of the saw-tooth chip morphology is found to be due to crack initiation at the free surface. However, as the cutting speed (and strain rate) increases, the formation of the discontinuous, particle-type chip morphology is found to be due to crack initiation at the tool tip. In addition, the influences of tool rake angle, particle size, and particle volume fracture are investigated and found to have little effect on the chip morphology and chip formation mechanism.}, number={9}, journal={Journal of Manufacturing Science and Engineering, Transactions of the ASME}, author={Davis, B. and Dabrow, D. and Ju, L. and Li, A. and Xu, C. and Huang, Y.}, year={2017} }
 @inproceedings{davis_dabrow_ju_li_xu_huang_2017, title={Study of chip morphology and chip formation mechanism during machining of magnesium-based metal matrix composites}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85027731034&partnerID=MN8TOARS}, DOI={10.1115/MSEC2017-3052}, abstractNote={Magnesium (Mg) and its alloys are among the lightest metallic structural materials, making them very attractive for use in the aerospace and automotive industries. Recently, Mg has been used in metal matrix composites (MMCs), demonstrating significant improvements in mechanical performance. However, the machinability of Mg-based MMCs is still largely elusive. In this study, Mg-based MMCs are machined using a wide range of cutting speeds in order to elucidate both the chip morphology and chip formation mechanism. Cutting speed is found to have the most significant influence on both the chip morphology and chip formation mechanism, with the propensity of discontinuous, particle-type chip formation increasing as the cutting speed increases. Saw-tooth chips are found to be the primary chip morphology at low cutting speeds (lower than 0.5 m/s), while discontinuous, particle-type chips prevail at high cutting speeds (higher than 1.0 m/s). Using in situ high speed imaging, the formation of the saw-tooth chip morphology is found to be due to crack initiation at the free surface. However, as the cutting speed (and strain rate) increases, the formation of the discontinuous, particle-type chip morphology is found to be due to crack initiation at the tool tip. In addition, the influences of tool rake angle, particle size, and particle volume fracture are investigated and found to have little effect on the chip morphology and chip formation mechanism.}, booktitle={ASME 2017 12th International Manufacturing Science and Engineering Conference, MSEC 2017 collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing}, author={Davis, B. and Dabrow, D. and Ju, L. and Li, A. and Xu, C. and Huang, Y.}, year={2017} }
 @article{qiao_liu_jia_xu_an_bai_2017, title={Study on coexistence of brittle and ductile fractures in nano reinforcement composites under different loading conditions}, volume={204}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85007238098&partnerID=MN8TOARS}, DOI={10.1007/s10704-016-0174-y}, number={2}, journal={International Journal of Fracture}, author={Qiao, Y. and Liu, J. and Jia, Y. and Xu, C. and An, L. and Bai, Y.}, year={2017}, pages={205–224} }
 @article{fan_wang_dong_wang_duan_mei_wang_cui_zhang_xu_2017, title={The role of the surface morphology and segmented cracks on the damage forms of laser re-melted thermal barrier coatings in presence of a molten salt (Na<inf>2</inf>SO<inf>4</inf> + V<inf>2</inf>O<inf>5</inf>)}, volume={115}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85006810370&partnerID=MN8TOARS}, DOI={10.1016/j.corsci.2016.11.011}, abstractNote={Hot corrosion behaviour of yttria-stabilized zirconia thermal barrier coatings (TBCs) with various segmented cracks and surface morphologies, obtained using ultrasonic-assisted laser re-melting, was investigated during exposure to Na2SO4 + V2O5 salt at 1100 °C. It is demonstrated, that the damage types of TBCs were significantly affected by segmented cracks and surface morphology. Four main damage mechanisms: (i) chemical reaction, (ii) Coefficient thermal mismatch stress, (iii) oxidation of bond coating and (iv) intergranular corrosion, based on the observed transport behaviour of oxygen and molten salt, stress-tolerance and self-healing of various segmented cracks, were discussed to account for the failure behaviour.}, journal={Corrosion Science}, author={Fan, Z. and Wang, K. and Dong, X. and Wang, R. and Duan, W. and Mei, X. and Wang, W. and Cui, J. and Zhang, S. and Xu, C.}, year={2017}, pages={56–67} }
 @misc{xu_ajayi_morales_2017, title={Thermal and Oxidation Stability of BNNT and BNNT Composites}, note={Invited}, author={Xu, C. and Ajayi, T. and Morales, J.}, year={2017} }
 @misc{xu_daniel_2017, title={Wireless Temperature Measurement Based on Radio Frequency (RF) Technology}, author={Xu, C. and Daniel, J.}, year={2017} }
 @article{yang_dong_webster_gilmore_xu_2016, title={Characterization and Alignment of Carbon Nanofibers under Shear Force in Microchannel}, volume={2016}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84962675850&partnerID=MN8TOARS}, DOI={10.1155/2016/1052478}, abstractNote={This work presents a novel method to align CNFs by using shear forces in microchannels. Effect of two different microchannel sizes (1 mm × 0.1 mm and 1 mm × 0.2 mm) on CNFs alignment is investigated. SEM images of CNFs preform display significant alignment by both microchannels, which can be interpreted using a second-order alignment tensor and a manual angle meter. In the second-order alignment tensor description, an elongated ellipse can signify high degree of alignment in the direction of the major axis. When the microchannel size is 1 mm × 0.2 mm, the lengths of major and minor axes of the ellipse are 0.982 to 0.018. An angle meter manually shows that 85% of the CNFs are aligned in the direction between 60° and 90° when the microchannel is 1 mm × 0.2 mm. Both methods can demonstrate that better alignment of CNFs can be obtained using the 1 mm × 0.2 mm microchannel.}, journal={Journal of Nanomaterials}, author={Yang, J. and Dong, S. and Webster, D. and Gilmore, J. and Xu, C.}, year={2016} }
 @inproceedings{xu_mousavinezhad_2016, title={Computer and Information Technology Tools in Signals & Systems}, url={http://dx.doi.org/10.18260/p.26552}, DOI={10.18260/p.26552}, booktitle={2016 ASEE Annual Conference & Exposition Proceedings}, publisher={ASEE Conferences}, author={Xu, Cheryl and Mousavinezhad, S.}, year={2016}, month={Jul} }
 @article{zhao_shao_li_xu_an_2016, title={Development of a Wireless Temperature Sensor Using Polymer-Derived Ceramics}, volume={2016}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84971280268&partnerID=MN8TOARS}, DOI={10.1155/2016/8624817}, abstractNote={A temperature sensor has been developed using an embedded system and a sensor head made of polymer-derived SiAlCN ceramics (PDCs). PDC is a promising material for measuring high temperature and the embedded system features low-power consumption, compact size, and wireless transmission. The developed temperature sensor has been experimentally tested to demonstrate the possibility of using such sensors for real world applications.}, journal={Journal of Sensors}, author={Zhao, R. and Shao, G. and Li, N. and Xu, C. and An, L.}, year={2016} }
 @article{fan_dong_wang_duan_wang_mei_wang_cui_yuan_xu_2016, title={Effect of drilling allowance on TBC delamination, spatter and re-melted cracks characteristics in laser drilling of TBC coated superalloys}, volume={106}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84962911187&partnerID=MN8TOARS}, DOI={10.1016/j.ijmachtools.2016.03.008}, abstractNote={Abstract Laser drilling of inclined holes on Ni-based superalloys coated with thermal barrier coatings (TBC) was studied using numerical simulation and experiments. Two types of drilling, three steps-laser drilling (TSLD) method and the one step laser drilling (OSLD), were employed for making comparison. The simulation results demonstrate that relatively strong vortex effect of assist gas at hole entrance and the drilling allowance of the substrate hole can deflect the trajectories of melt flow from leading edge TBC wall. This phenomenon may isolate leading edge of the hole from the ejecting molten material. Thus, shearing stress effect was prevented. The characteristics of TBC delamination, spatter at the TBC leading edge and re-melted cracks along the TBC trailing edge are investigated by comparing the characteristics of the melt flow obtained via simulation and experiment. The combined results suggest that the TBC/substrate multilayer can avoid these defects applying the TSLD technology.}, journal={International Journal of Machine Tools and Manufacture}, author={Fan, Z. and Dong, X. and Wang, K. and Duan, W. and Wang, R. and Mei, X. and Wang, W. and Cui, J. and Yuan, X. and Xu, C.}, year={2016}, pages={1–10} }
 @article{bade_li_shan_ling_tian_dilbeck_besara_geske_gao_ma_et al._2016, title={Fully Printed Halide Perovskite Light-Emitting Diodes with Silver Nanowire Electrodes}, volume={10}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84961221465&partnerID=MN8TOARS}, DOI={10.1021/acsnano.5b07506}, abstractNote={Printed organometal halide perovskite light-emitting diodes (LEDs) are reported that have indium tin oxide (ITO) or carbon nanotubes (CNTs) as the transparent anode, a printed composite film consisting of methylammonium lead tribromide (Br-Pero) and poly(ethylene oxide) (PEO) as the emissive layer, and printed silver nanowires as the cathode. The fabrication can be carried out in ambient air without humidity control. The devices on ITO/glass have a low turn-on voltage of 2.6 V, a maximum luminance intensity of 21014 cd m(-2), and a maximum external quantum efficiency (EQE) of 1.1%, surpassing previous reported perovskite LEDs. The devices on CNTs/polymer were able to be strained to 5 mm radius of curvature without affecting device properties.}, number={2}, journal={ACS Nano}, author={Bade, S.G.R. and Li, J. and Shan, X. and Ling, Y. and Tian, Y. and Dilbeck, T. and Besara, T. and Geske, T. and Gao, H. and Ma, B. and et al.}, year={2016}, pages={1795–1801} }
 @misc{xu_2016, title={High Conductive Ceramic Thin Film with Unique Mechanical Property}, note={Invited}, author={Xu, C.}, year={2016} }
 @article{yang_downes_schrand_park_liang_xu_2016, title={High electrical conductivity and anisotropy of aligned carbon nanotube nanocomposites reinforced by silicon carbonitride}, volume={124}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84978035561&partnerID=MN8TOARS}, DOI={10.1016/j.scriptamat.2016.06.023}, abstractNote={Aligned carbon nanotube (CNT) sheets reinforced with silicon carbonitride were prepared by the infiltration and pyrolysis of liquid polysilazane into mechanically stretched CNTs. The resultant nanocomposites contained a high volume fraction of CNTs (60 vol%), and due to alignment, reached an electrical conductivity of up to 2.2 × 105 S m− 1. The electrical conductivity was anisotropic based upon the CNT alignment and changed from 3.3 to 9.2 after the pyrolysis process. The high electrical conductivity of the nanocomposites contributes to their potential application in electromagnetic interference shielding.}, journal={Scripta Materialia}, author={Yang, J. and Downes, R. and Schrand, A. and Park, J.G. and Liang, R. and Xu, C.}, year={2016}, pages={21–25} }
 @article{yang_dong_xu_2016, title={Mechanical response and microstructure of 2D carbon fiber reinforced ceramic matrix composites with SiC and Ti<inf>3</inf>SiC<inf>2</inf>fillers}, volume={42}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84949965271&partnerID=MN8TOARS}, DOI={10.1016/j.ceramint.2015.10.088}, abstractNote={2D carbon fiber reinforced ceramic matrix composites are prepared by PIP process using SiC and Ti3SiC2 as separate fillers. The effect of SiC and Ti3SiC2 fillers on mechanical property, fracture behavior and microstructure of the final composites is studied. The force–displacement curve shows no apparent delamination in Cf/Ti3SiC2–SiC composites during three-point flexural test, compared to Cf/SiC composites in which the through-thickness crack is much more devious. The ultimate force of Cf/Ti3SiC2–SiC composites is much lower than Cf/SiC composites. The thermal expansion mismatch and chemical reactions between carbon fiber and the matrix make the fiber–matrix interface bonding stronger in Cf/Ti3SiC2–SiC composites. It can infer that the carbon fibers׳ strength can be damaged by the chemical reactions. The thermal expansion mismatch and chemical reactions are two important factors that influence the mechanical properties and microstructure of the final composites.}, number={2}, journal={Ceramics International}, author={Yang, J. and Dong, S. and Xu, C.}, year={2016}, pages={3019–3027} }
 @article{zhu_dong_ni_xu_wang_2016, title={Microstructure, mechanical properties and oxidation resistance of SiC<inf>f</inf>/SiC composites incorporated with boron nitride nanotubes}, volume={6}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84986302081&partnerID=MN8TOARS}, DOI={10.1039/c6ra16496j}, abstractNote={SiC<sub>f</sub>/BNNTs–SiC hierarchical composites were fabricated <italic>via</italic> firstly <italic>in situ</italic> growth of BNNTs on SiC fibers using boron powder as a raw material and then matrix densification by chemical vapor infiltration and polymer impregnation/pyrolysis methods.}, number={86}, journal={RSC Advances}, author={Zhu, G. and Dong, S. and Ni, D. and Xu, C. and Wang, D.}, year={2016}, pages={83482–83492} }
 @misc{xu_2016, title={Strong and Flexible Ceramic Composites with High In-Plane Thermal Conductivity for Hypersonic Applications}, note={Invited}, author={Xu, C.}, year={2016} }
 @article{yang_downes_yu_park_liang_xu_2016, title={Strong and ultra-flexible polymer-derived silicon carbonitride nanocomposites by aligned carbon nanotubes}, volume={42}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84970023718&partnerID=MN8TOARS}, DOI={10.1016/j.ceramint.2016.05.078}, abstractNote={We report the synthesis of flexible ceramic composites with a high tensile strength (536.33±7.23 MPa) using carbon nanotube sheet aligned by mechanically stretching process. The process is based on the infiltration and pyrolysis of liquid ceramic precursor into aligned carbon nanotube sheet. Mechanical properties and microstructure of the resultant composites are investigated. The resultant nanocomposites maintain well-aligned carbon nanotube morphology with high volume fraction (60%) and long pullout (15 µm), contributing to a high degree of load-transfer efficiency and toughening. Flexibility test reveals that such ceramic nanocomposites retain the original mechanical properties and microstructures after one thousand repetitions of 75% bending deformation, showing excellent compliance and durability. Applications requiring materials with high flexibility and mechanical properties can benefit from this research.}, number={12}, journal={Ceramics International}, author={Yang, J. and Downes, R. and Yu, Z. and Park, J.G. and Liang, R. and Xu, C.}, year={2016}, pages={13359–13367} }
 @inproceedings{xu_wentworth_mousavinezhad_2016, title={Teaching and Learning of Engineering Topics with Software Tools}, author={Xu, C. and Wentworth, S. and Mousavinezhad, H.}, year={2016} }
 @misc{xu_yang_2016, title={Three-Dimensional Multi-Reinforced Ceramic Composites with Enhanced Through-Thickness Thermal Conductivity}, note={Invited}, author={Xu, C. and Yang, J.}, year={2016} }
 @article{yang_sprengard_ju_hao_saei_liang_cheng_xu_2016, title={Three-dimensional-linked carbon fiber-carbon nanotube hybrid structure for enhancing thermal conductivity of silicon carbonitride matrix composites}, volume={108}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84978811183&partnerID=MN8TOARS}, DOI={10.1016/j.carbon.2016.07.002}, abstractNote={Abstract In this paper, a novel three-dimensional-linked (3D-linked) carbon fiber-carbon nanotube (C f -CNT) hybrid structure is presented to improve the through-thickness thermal properties of polymer derived silicon carbonitride matrix composites. Comparing with pristine plain woven carbon fiber, the pores in the criss-cross position are fully filled with carbon nanotubes (CNT) in the presented C f -CNT hybrid structure. CNT can be integrated in between the plain woven carbon fibers and generate a 3D-linked C f -CNT hybrid network structure. Thanks to the percolating network of CNT and the densification effect, the through-thickness thermal conductivity of the resultant ceramic matrix composites is improved significantly, which is enhanced by 10% with short CNT and by 31% with long CNT, respectively. The thermal conductivity is found to increase with temperature from 100 to 900 °C for these composites. Multiphysics simulation is conducted to reveal the effects of the 3D-linked C f -CNT hybrid structure on the thermal conductivity at various temperatures, which are consistent with experimental results.}, journal={Carbon}, author={Yang, J. and Sprengard, J. and Ju, L. and Hao, A. and Saei, M. and Liang, R. and Cheng, G.J. and Xu, C.}, year={2016}, pages={38–46} }
 @article{pan_liu_choi_xu_bai_atkins_2016, title={Zones of material separation in simulations of cutting}, volume={115-116}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84979503610&partnerID=MN8TOARS}, DOI={10.1016/j.ijmecsci.2016.06.019}, abstractNote={FEM simulations of orthogonal cutting are reported in which both the Johnson–Cook (JC) constitutive relation and the Johnson–Cook separation (fracture or damage) criterion are used. Results demonstrate that the damaged regions, in which separation of material occurs at the tool tip, form thin boundary layers on the top of the machined surface and on the underside of the chip. Damage was calculated in terms of the parameters of the Johnson–Cook fracture criterion appropriate for A2024-T351 aluminium alloy. The size of the damaged layers is some 35 μm and appears to be independent of the uncut chip thickness t0 over the range investigated (50<t0<500 μm). In most cases, the highly-damaged boundary layers make up only a very small proportion of the uncut chip thickness, so the deformation fields by which chips are formed are essentially the same as if the damage zone were absent. The result explains the success of variables-separable algebraic models of cutting with continuous chips in which the component works of chip plasticity, friction and separation are uncoupled.

The FEM simulations predict quasi-linear relations between cutting force and uncut chip thickness, with an intercept on the force axis. This is exactly what is found experimentally and is predicted by algebraic models of continuous chip cutting under the assumption of sharp tool tip, where the slope of the plot relates to the yield stress of the workpiece and the intercept to its fracture toughness. The fracture toughness and the parameters of the JC damage relation, along with the size of the boundary layers of damage, are shown to be related.}, journal={International Journal of Mechanical Sciences}, author={Pan, H. and Liu, J. and Choi, Y. and Xu, C. and Bai, Y. and Atkins, T.}, year={2016}, pages={262–279} }
 @misc{xu_2015, title={Ceramic Matrix Composites (CMCs) with High Volume Fractions of Reinforcements (up to 60 Vol.%) and Ensuring 3-Dimensional Bonding Strength}, author={Xu, C.}, year={2015} }
 @inproceedings{xu_mousavinezhad_2015, title={Computer-aided design (CAD) of recursive/non-recursive filters}, volume={122nd ASEE Annual Conference and Exposition: Making Value for Society}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84941994086&partnerID=MN8TOARS}, number={122nd ASEE Annual Conference and Exposition: Making Value for Society}, booktitle={ASEE Annual Conference and Exposition, Conference Proceedings}, author={Xu, C. and Mousavinezhad, S.H.}, year={2015} }
 @misc{xu_yang_l._jiang_wang_2015, title={Effective Nano-Infiltration to Make Fully-Densed Ceramic Composites with A High Volume Fraction of Reinforcements}, author={Xu, C. and Yang, J. and L., Ju and Jiang, Z. and Wang, H.}, year={2015} }
 @misc{xu_2015, title={Flexible Ceramic Composites with High In-Plane Thermal Conductivity}, note={Invited}, author={Xu, C.}, year={2015} }
 @misc{yang_xu_ju_downes_hao_liang_2015, title={Flexible Ceramic Matrix Composite with High Strength and Conductive by Aligned CNTs}, author={Yang, J. and Xu, C. and Ju, L. and Downes, R. and Hao, A. and Liang, R.}, year={2015} }
 @misc{xu_2015, title={Flexible Ceramic Thin Film with High Conductivity}, author={Xu, C.}, year={2015} }
 @article{xu_2015, title={Multifunctional Flexible Ceramic Membranes}, volume={2}, journal={Naval Science and Technology – Future Force}, author={Xu, C.}, year={2015}, pages={26} }
 @article{liu_bai_xu_2014, title={Evaluation of ductile fracture models in finite element simulation of metal cutting processes}, volume={136}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894082831&partnerID=MN8TOARS}, DOI={10.1115/1.4025625}, abstractNote={In this paper, a systematic evaluation of six ductile fracture models is conducted to identify the most suitable fracture criterion for metal cutting processes. Six fracture models are evaluated in this study, including constant fracture strain, Johnson-Cook, Johnson-Cook coupling criterion, Wilkins, modified Cockcroft-Latham, and Bao-Wierzbicki fracture criterion. By means of abaqus built-in commands and a user material subroutine (VUMAT), these fracture models are implemented into a finite element (FE) model of orthogonal cutting processes in abaqus/Explicit platform. The local parameters (stress, strain, fracture factor, and velocity fields) and global variables (chip morphology, cutting forces, temperature, shear angle, and machined surface integrity) are evaluated. The numerical simulation results are examined by comparing to experimental results of 2024-T3 aluminum alloy published in the open literature. Based on the results, it is found that damage evolution should be considered in cutting process FE simulation. Moreover, the B-W fracture model with consideration of rate dependency, temperature effect and damage evolution gives the best prediction of chip removal behavior of ductile metals.}, number={1}, journal={Journal of Manufacturing Science and Engineering, Transactions of the ASME}, author={Liu, J. and Bai, Y. and Xu, C.}, year={2014} }
 @article{cheng_shao_ebadi_ren_harris_liu_xu_an_gong_2014, title={Evanescent-mode-resonator-based and antenna-integrated wireless passive pressure sensors for harsh-environment applications}, volume={220}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84957042668&partnerID=MN8TOARS}, DOI={10.1016/j.sna.2014.09.010}, abstractNote={Abstract A wireless pressure sensor for high-temperature applications is demonstrated based on a microwave evanescent-mode cavity resonator. Cavity deformation resulting from applied external pressure can be detected by measuring the resonant frequency change of the sensor. Compact sensor size is achieved by loading a cylindrical post inside the cavity resonator. In addition, a patch antenna is seamlessly integrated with the pressure sensor, without additional volume. This pressure sensor is able to survive high temperatures by adopting passive structures and robust ceramic/metallic materials. Fully-dense silicoaluminum carbonitride (SiAlCN) ceramic is used herein owing to its excellent thermal–mechanical properties and manufacturability as a Polymer-Derived Ceramic (PDC). A PDC soft-lithography technique is developed to fabricate the ceramic pressure sensor. In order to wirelessly interrogate the pressure sensor at high temperatures, a robust interrogation antenna is designed and fabricated with a wide fractional bandwidth. Finally, the cavity deformation of pressure sensor versus external pressure is measured at high temperatures up to 800 °C. The resonant frequency decreases from 11.75 to 11.56 GHz, when the applied external force on the sensor increases from 0 to 5 N at 800 °C.}, journal={Sensors and Actuators, A: Physical}, author={Cheng, H. and Shao, G. and Ebadi, S. and Ren, X. and Harris, K. and Liu, J. and Xu, C. and An, L. and Gong, X.}, year={2014}, pages={22–33} }
 @article{liu_li_xu_2014, title={Interaction of the cutting tools and the ceramic-reinforced metal matrix composites during micro-machining: A review}, volume={7}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894105664&partnerID=MN8TOARS}, DOI={10.1016/j.cirpj.2014.01.003}, abstractNote={High performance ceramic-reinforced metal matrix composites (MMCs) are becoming widely popular in industry and the mechanical machining method is one of the most suitable manufacturing techniques for near net shape MMC components. This paper provides a comprehensive literature review to enhance the fundamental understanding of the tool–workpiece interactions in micro-scale during cutting process on engineered-heterogeneous materials. The paper focuses on mechanical properties, fracture mechanism and machinability of ceramic-reinforced MMCs, with significant emphasis on the chip formation mechanism considering different dominant effects, such as materials strengthening mechanisms, micro-structural effect, size effect and minimum chip thickness effect. It also includes some work that, while not directly focused on micro-scale cutting ceramic-reinforced MMCs, but provided important insight to the field of cutting engineered-heterogeneous materials (non-eutectic). Furthermore, process modeling studies for micro-scale cutting are also surveyed, including the cutting force modeling, dynamics modeling and surface generation modeling. The comments on future needs and directions are provided at the end.}, number={2}, journal={CIRP Journal of Manufacturing Science and Technology}, author={Liu, J. and Li, J. and Xu, C.}, year={2014}, pages={55–70} }
 @misc{yang_xu_2014, title={Optimization of Carbon Nanofibers Alignment Induced by Shear Force}, author={Yang, J. and Xu, C.}, year={2014} }
 @article{ji_xu_2014, title={Sliding Mode Control of Feed Drive System for a Three-axis Micro-Machining Platform with Nano-Resolution}, volume={4}, number={1}, journal={Journal of Control Engineering and Technology}, author={Ji, Y. and Xu, C.}, year={2014}, pages={29–36} }
 @article{zhao_shao_cao_an_xu_2014, title={Temperature sensor made of polymer-derived ceramics for high-temperature applications}, volume={219}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84907528396&partnerID=MN8TOARS}, DOI={10.1016/j.sna.2014.08.012}, abstractNote={Abstract This paper describes the use of polymer-derived SiAlCN (silicoaluminum carbonitride) ceramics (PDC) to fabricate a temperature sensor for high-temperature applications. A unique sensor head was designed and fabricated with Pt wires seamlessly embedded in as electrodes. Material characterization test demonstrates that the resistance of the senor head decreases monotonically with surrounding temperature, suggesting its readiness to be used for temperature measurement. In actual experiment (temperature up to 830 °C), the measurement of the PDC sensor demonstrates good repeatability to both unidirectional and bidirectional temperature variations for the total span of 10 h, and its measurement follows closely with the thermal couple measurement. These results demonstrated that the temperature sensors made of polymer-derived ceramics (PDC) have excellent accuracy and repeatability, and can be used in high temperature environment.}, journal={Sensors and Actuators, A: Physical}, author={Zhao, R. and Shao, G. and Cao, Y. and An, L. and Xu, C.}, year={2014}, pages={58–64} }
 @inproceedings{zhao_xu_2013, title={Analytical modeling and experimental validation of force ripple and friction force for general direct drive systems}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890282920&partnerID=MN8TOARS}, DOI={10.1115/MSEC2013-1058}, abstractNote={In this paper, we present a systematic modeling method of direct drive systems. Experiments are designed to decouple and model friction and force ripple separately, which are two major sources of tracking error. Three different optimization methods, least square method, nonlinear least square method and particle swarm optimization are used for parameter optimization. The analytical form of the model makes it easy to use in engineering practices. All results are obtained and verified experimentally. The method presented in this paper can also be used to model other mechanical systems.}, booktitle={ASME 2013 International Manufacturing Science and Engineering Conference Collocated with the 41st North American Manufacturing Research Conference, MSEC 2013}, author={Zhao, R. and Xu, C.}, year={2013} }
 @article{liu_li_xu_2013, title={Cutting force prediction on micromilling magnesium metal matrix composites with nanoreinforcements}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84894092314&partnerID=MN8TOARS}, DOI={10.1115/1.4023286}, abstractNote={Due to its light weight, high creep, and wear resistance, magnesium metal matrix composites (Mg-MMCs) with nanosized reinforcements are promising for various industrial applications, especially those with high volume fractions of reinforcements. The machinability of Mg-MMCs and related cutting process modeling are important to study. In this paper, an analytical cutting force model is developed to predict cutting forces of Mg-MMC reinforced with SiC nanoparticles in micromilling process. This model is different from previous ones by encompassing the behaviors of nanoparticle reinforcements in three cutting scenarios, i.e., shearing, ploughing, and elastic recovery. By using the enhanced yield strength in the cutting force model, three major strengthening factors are incorporated, including load-bearing effect, enhanced dislocation density strengthening effect, and Orowan strengthening effect. In this way, material properties, such as the particle size and volume fraction as significant factors affecting the cutting forces, are explicitly considered. To validate the model, experiments based on various cutting conditions using two types of end mills (diameters as 100 μm and 1 mm) were conducted on pure Mg, Mg-MMCs with volume fractions of 5 vol. %, 10 vol. %, and 15 vol. %. The experimental results show a good agreement with the predicted cutting force value.}, number={1}, journal={Journal of Micro and Nano-Manufacturing}, author={Liu, J. and Li, J. and Xu, C.}, year={2013} }
 @article{lojewski_yang_duan_xu_deng_2013, title={Design, fabrication, and characterization of linear multiplexed electrospray atomizers micro-machined from metal and polymers}, volume={47}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84876791780&partnerID=MN8TOARS}, DOI={10.1080/02786826.2012.734936}, abstractNote={Multiplexed electrospray is a promising aerosol generation technique to produce high throughput quasi-monodisperse droplets in the nanometer and micron size range. Here we report the design, fabrication, analysis, and performance of a linear electrospray (LINES) system. The fabrication of the nozzle array is based on a precision computer numerical control (CNC) micromachining platform with 1-micron resolution. This rapid prototyping approach offers the flexibility of creating devices from a wide range of materials including metals and polymers with packing densities on par with silicon microfabrication at 20 sources/cm for LINES devices and 460 sources/cm2 for the two-dimensional array. The LINES device uses a slot extractor design to simplify alignment and enhance operation robustness. We also used dummy nozzles (posts without fluidic channels) to offset edge effect on electric field and improved droplet size uniformity. We derived the approximate spray expansion model from charge conservation and Gauss’...}, number={2}, journal={Aerosol Science and Technology}, author={Lojewski, B. and Yang, W. and Duan, H. and Xu, C. and Deng, W.}, year={2013}, pages={146–152} }
 @article{li_liu_liu_ji_xu_2013, title={Experimental investigation on the machinability of SiC nano-particles reinforced magnesium nanocomposites during micro-milling processes}, volume={8}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84873342204&partnerID=MN8TOARS}, DOI={10.1504/IJMR.2013.051840}, abstractNote={This paper experimentally investigates the machinability of magnesium metal matrix composites (Mg-MMCs) with high volume fractions of SiC nano-particles using micro-milling process. The nanocomposites containing 5 vol.%, 10 vol.% and 15 vol.% reinforcements of SiC nano-particles were studied and compared with pure magnesium. The milling was carried out at different feedrates and spindle speeds chosen according to design of experiment (DOE) method. Cutting forces, surface morphology and surface roughness were measured to understand the machinability of the four different materials. Based on response surface methodology (RSM) design, experimental models and related contour plots were developed to build a connection between material properties and cutting parameters. Those models can be used to predict the cutting force, the surface roughness, and then optimise the machining conditions with the required cutting forces and surface roughness.}, number={1}, journal={International Journal of Manufacturing Research}, author={Li, J. and Liu, J. and Liu, J. and Ji, Y. and Xu, C.}, year={2013}, pages={64–84} }
 @misc{shao_freese_xu_an_2013, title={Polymer Derived Ceramic Sensors for Ultra-High Temperature Application}, author={Shao, G. and Freese, D. and Xu, C. and An, L.}, year={2013} }
 @inproceedings{freese_shao_xu_2013, title={Polymer-derived ceramic sensors for temperature measurement in harsh environment}, volume={4}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84890205551&partnerID=MN8TOARS}, DOI={10.1115/GT2013-96031}, abstractNote={Development of an ultra-high temperature sensor advocates numerous applications in a variety of diverse fields. Combustion turbine engine advancements are predominately the benefactors of high temperature measurement capabilities; founded upon the principle of higher combustion reaction efficiency. The interior combustion chamber of a gas turbine is an extremely hostile environment for any typical material, especially a measurement component. Implementing the conductive properties and high temperature stability of a polymer derived ceramic (PDC) offers a solution to this predicament. Complementing the virtuous mechanical properties of the unique ceramic is micro-machinability and tunable electric characteristics established from the precursor compounds. The thermo-electric qualities of the PDC prepare formulation of a relationship between the changing temperatures of the research environment with respect to the internal resistance of the ceramic. An elected measurement system will actively monitor a PDC sensory circuit as well as reference thermocouple temperature. Series of response experiments were performed to characterize the functionality of the sensor within the high temperature environment.}, booktitle={Proceedings of the ASME Turbo Expo}, author={Freese, D. and Shao, G. and Xu, C.}, year={2013} }
 @article{xu_shin_2012, title={A multilevel fuzzy control design for a class of multiinput single-output systems}, volume={59}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84859704762&partnerID=MN8TOARS}, DOI={10.1109/TIE.2011.2158033}, abstractNote={In this paper, an adaptive fuzzy controller is developed for a class of multiinput single-output nonlinear systems, where the system differential output has a monotonically increasing or decreasing relationship with each system differential input. The system dynamics is modeled in fuzzy domain, and the fuzzy inverse model is automatically constructed, which uniquely determines the inverse relationship for each differential input-output pair. Based on this inverse model, a multilevel fuzzy controller is designed with an embedded adaptive structure for each control variable to compensate for system uncertainties and time-varying parameters. Two sets of simulation examples are presented to illustrate the effectiveness of the proposed controller for this class of multivariable systems under different operating conditions.}, number={8}, journal={IEEE Transactions on Industrial Electronics}, author={Xu, C. and Shin, Y.C.}, year={2012}, pages={3113–3123} }
 @article{shao_zhao_yang_xu_an_2012, title={Ceramic nanocomposites reinforced with a high volume fraction of carbon nanofibers}, volume={68}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80855156612&partnerID=MN8TOARS}, DOI={10.1016/j.matlet.2011.10.031}, abstractNote={A ceramic nanocomposite reinforced with about 20 vol.% of carbon nanofibers (CNFs) is fabricated by infiltrating CNF-preform with liquid-phased polymeric precursor following by pyrolysis. The nanocomposite has a dense structure without micro-cracks. The results from the microindentation tests reveal that the nanocomposite has lower indentation hardness but higher fracture energy than the non-reinforced ceramic. The effect of the CFTs on the mechanical properties of the nanocomposite has been discussed.}, journal={Materials Letters}, author={Shao, G. and Zhao, G. and Yang, F. and Xu, C. and An, L.}, year={2012}, pages={108–111} }
 @article{ji_hernandez_giesecke_bartles_xu_2012, title={Tool Wear Analysis Using Wavelet Transform Based Cutting Force and Acoustic Emission}, volume={2}, number={2}, journal={Journal of Aviation and Aerospace Perspective}, author={Ji, Y. and Hernandez, M. and Giesecke, D. and Bartles, D. and Xu, C.}, year={2012}, pages={35–54} }
 @inproceedings{gong_an_xu_2012, title={Wireless passive sensor development for harsh environment applications}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84860655150&partnerID=MN8TOARS}, DOI={10.1109/IWAT.2012.6178418}, abstractNote={Three researchers at University of Central Florida from electrical engineering, materials science, and mechanical engineering teamed together to develop high-temperature (> 1000°C) sensors for various harsh environment applications such as combustion turbines. In this paper, we will provide an overview of the recent progress in the development of sensing materials, sensor fabrication methods, and wireless sensing techniques.}, booktitle={2012 IEEE International Workshop on Antenna Technology, iWAT 2012}, author={Gong, X. and An, L. and Xu, C.}, year={2012}, pages={140–143} }
 @article{xu_shin_2011, title={A self-tuning fuzzy controller for a class of multi-input multi-output nonlinear systems}, volume={24}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79151477967&partnerID=MN8TOARS}, DOI={10.1016/j.engappai.2010.10.021}, abstractNote={This paper presents a systematic design procedure of a multivariable fuzzy controller for a general Multi-Input Multi-Output (MIMO) nonlinear system with an input-output monotonic relationship or a piecewise monotonic relationship for each input-output pair. Firstly, the system is modeled as a Fuzzy Basis Function Network (FBFN) and its Relative Gain Array (RGA) is calculated based on the obtained fuzzy model. The proposed multivariable fuzzy controller is constructed with two orthogonal fuzzy control engines. The horizontal fuzzy control engine for each system input-output pair has a hierarchical structure to update the control parameters online and compensate for unknown system variations. The perpendicular fuzzy control engine is designed based on the system RGA to eliminate the multivariable interaction effect. The resultant closed-loop fuzzy control system is proved to be passive stable as long as the augmented open-loop system is input-output passive. Two sets of simulation examples demonstrate that the proposed fuzzy control strategy can be a promising way in controlling multivariable nonlinear systems with unknown system uncertainties and time-varying parameters.}, number={2}, journal={Engineering Applications of Artificial Intelligence}, author={Xu, C. and Shin, Y.C.}, year={2011}, pages={238–250} }
 @article{an_qu_luo_fan_zhang_liu_xu_blau_2011, title={Aluminum nanocomposites having wear resistance better than stainless steel}, volume={26}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84873392830&partnerID=MN8TOARS}, DOI={10.1557/jmr.2011.263}, number={19}, journal={Journal of Materials Research}, author={An, L. and Qu, J. and Luo, J. and Fan, Y. and Zhang, L. and Liu, J. and Xu, C. and Blau, P.J.}, year={2011}, pages={2479–2483} }
 @inproceedings{deane_hernandez_giesecke_meanor_collins_ji_xu_2011, title={Analysis of a simultaneous CNC turning and boring operation via multisensor monitoring}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82455166830&partnerID=MN8TOARS}, DOI={10.1115/MSEC2011-50168}, abstractNote={The introduction of multi-axis CNC machining has reduced machining time and increased production rates. However, optimizing simultaneous operations to produce quality parts and prolong tool life still possesses a challenge to engineers due to the mutual interactions of two tools removing material and the amount of factors and noise in a production environment. Since there are multiple factors and the sources of error are unknown, we use a statistical approach to obtain and organize information. A design of experiment study was implemented across twelve sensor responses to optimize the spindle speed, feed rate, inner diameter (ID) depth of cut and outer diameter (OD) depth of cut for simultaneous turning and boring roughing operations. The optimal machining conditions were obtained by a response optimizer from Minitab 16 statistical software. The optimized settings result in 13% reduced cutting and 10% reduced total power consumption for a 3% increase of average power. Future studies will cross correlate different responses to reduce the number of sensors in developing a robust adaptive controller for chatter detection and tool condition monitoring.}, booktitle={ASME 2011 International Manufacturing Science and Engineering Conference, MSEC 2011}, author={Deane, E. and Hernandez, M. and Giesecke, D. and Meanor, M. and Collins, S. and Ji, Y. and Xu, C.}, year={2011}, pages={273–280} }
 @misc{liu_li_shao_ji_xu_an_2011, title={Investigation of Micro-End-Milling of Polymer-Derived Ceramics for High Temperature Micro-Sensor Fabrication}, author={Liu, J. and Li, J. and Shao, G. and Ji, Y. and Xu, C. and An, L.}, year={2011} }
 @inproceedings{liu_li_ji_xu_2011, title={Investigation on the effect of SiC nanoparticles on cutting forces for micro-milling Magnesium Matrix Composites}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82455175639&partnerID=MN8TOARS}, DOI={10.1115/MSEC2011-50170}, abstractNote={Magnesium Metal Matrix Composites (Mg-MMCs) with nano-sized reinforcements exhibit better mechanical properties comparing to pure Magnesium (Mg) and its alloys. However, it is challenging to improve the machinability of this kind of composites. An analytical cutting force model for the micro-milling process was developed and validated to analyze the micro-machinability of the SiC nanoparticles reinforced Mg-MMCs. This model is different from the previous ones because it encompasses the behaviors of the reinforcement nanoparticles in the three cutting regimes, i.e., shearing, ploughing and elastic recovery. The volume fraction of particles and particle size are considered as two significant factors affecting the cutting forces in this model. The effects of the reinforcement nanoparticles on cutting forces were studied through modeling and experimental validation. The simulated cutting forces show a good agreement with the experimental data. Moreover, it is indicated that the amplitude and profile of cutting forces vary with the reinforcement particle’s volume fraction. This mainly arises from the strengthening effect of SiC nanoparticles.}, booktitle={ASME 2011 International Manufacturing Science and Engineering Conference, MSEC 2011}, author={Liu, J. and Li, J. and Ji, Y. and Xu, C.}, year={2011}, pages={525–536} }
 @inproceedings{ji_zhao_xu_2011, title={Modeling and control of feed drive system for a micro-machining platform with nano-resolution}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84881465535&partnerID=MN8TOARS}, DOI={10.1115/DSCC2011-6026}, abstractNote={The feed drive system plays a key role of increasing processing efficiency and improving machining quality of parts. The external disturbances, such as cutting forces and frictional nonlinearities seriously affect the machining quality. The feed drive system should be capable of rejecting such disturbances. In this paper, the feed drive system of a micro-machining platform with nano-resolution was modeled and controlled. A decoupled algorithm was implemented to linearly regulate flux-producing and force-producing currents of motor. The current controller was designed based on the electrical model of motor employing pole-zero cancellation method. The speed controllers, i.e., proportional-integral (PI) and sliding mode control (SMC) were designed and compared. The SMC exhibits the better property of rejecting the external disturbance compared to PI controller. The electromagnetic force produced by Linear Permanent Magnet Synchronous Machine (LPMSM) under SMC expresses the quicker response to external variations. The models will be further applied for the design of cross-coupling servo control for this five-axis reconfigurable micro-machining platform.}, booktitle={ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, DSCC 2011}, author={Ji, Y. and Zhao, R. and Xu, C.}, year={2011}, pages={263–270} }
 @misc{gong_an_xu_2011, title={Recent Advances on Wireless Passive High-Temperature Sensors for Harsh Environments}, note={Invited}, author={Gong, X. and An, L. and Xu, C.}, year={2011} }
 @article{chen_li_wang_zhang_xu_wei_an_2011, title={Self-assembled carbon-silicon carbonitride nanocomposites: High-performance anode materials for lithium-ion batteries}, volume={21}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80755125485&partnerID=MN8TOARS}, DOI={10.1039/c1jm13733f}, abstractNote={A new class of nanocomposites comprising an amorphous silicon carbonitride matrix and carbon nanoclusters was synthesized by decomposing polymeric precursors with thermally induced phase separation. Electrochemical measurements show that the nanocomposite with 30% of carbon nanoclusters exhibits a specific capacity of 480 mA h g−1 and excellent cycling performance. The high capacity of the nanocomposites is attributed to the formation of a novel structure around the SiCN–C interface. The excellent electrochemical properties, together with the simple, low-cost processing, make the nanocomposites very promising for Li-ion battery applications.}, number={45}, journal={Journal of Materials Chemistry}, author={Chen, Y. and Li, C. and Wang, Y. and Zhang, Q. and Xu, C. and Wei, B. and An, L.}, year={2011}, pages={18186–18190} }
 @article{yu_yang_xu_fang_an_2011, title={Synthesis of nanostructured silicon carbide at ultralow temperature using self-assembled polymer micelles as a precursor}, volume={21}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80455137269&partnerID=MN8TOARS}, DOI={10.1039/c1jm13973h}, abstractNote={Nanostructured SiC ceramics exhibit unusual and superior properties compared to their microstructured counterparts, thus hold promise for widespread applications. We report a novel technique for synthesizing dense nanostructured SiC at an ultralow-temperature without pressure. In this technique, polyvinylsilazane-block-polystyrene (PVSZ-b-PS) block copolymers were synthesized and then self-assembled into nano-scaled micelles with the precursor PVSZ as the core and the sacrificial PS as the shell. The subsequent pyrolysis converted the aggregation of the micelles into dense nanostructured SiC with a grain size of ∼20–30 nm at 800 °C.}, number={44}, journal={Journal of Materials Chemistry}, author={Yu, Y. and Yang, X. and Xu, C. and Fang, J. and An, L.}, year={2011}, pages={17619–17622} }
 @article{yu_chen_xu_fang_an_2011, title={Synthesis of spherical non-oxide silicon carbonitride ceramic particles}, volume={94}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-80052973104&partnerID=MN8TOARS}, DOI={10.1111/j.1551-2916.2011.04713.x}, abstractNote={In this article, we report a simple technique for synthesizing spherical non-oxide silicon carbonitride ceramic particles from a polysilazane precursor. In this technique, the spherical particles of the polysilazane precursor were synthesized first via a precipitation polymerization process and then converted to ceramic particles by pyrolysis. The resultant ceramic particles exhibited a close-to-perfect spherical shape and a narrow size distribution around 430 nm. The precipitation and pyrolysis processes were characterized using SEM, TEM, FTIR, and XRD to illustrate the formation mechanisms of the ceramic particles.}, number={9}, journal={Journal of the American Ceramic Society}, author={Yu, Y. and Chen, Y. and Xu, C. and Fang, J. and An, L.}, year={2011}, pages={2779–2782} }
 @book{liu_xu_jackson_2011, title={Traditional and non-traditional control techniques for grinding processes}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84889788116&partnerID=MN8TOARS}, DOI={10.1007/978-1-4419-7302-3_6}, journal={Machining with Abrasives}, author={Liu, J. and Xu, C. and Jackson, M.}, year={2011}, pages={269–302} }
 @inproceedings{liu_li_grummel_xu_shen_2010, title={A Contactless Polymer Derived Ceramic Temperature Sensing System for Turbine Applications}, author={Liu, J. and Li, J. and Grummel, B. and Xu, C. and Shen, J.}, year={2010} }
 @inproceedings{idahosa_saha_khatami_xu_basu_2010, title={Acoustic perturbation effects on the fluid dynamics and swirling flame response in a non-premixed co-flow burner}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82055207375&partnerID=MN8TOARS}, DOI={10.1115/GT2010-23735}, abstractNote={An investigation into the response of non-premixed swirling flames to acoustic perturbations at various frequencies (fp = 0–315 Hz) and swirl intensities (S = 0.09 and 0.34) is carried out. Perturbations are generated using a loudspeaker at the base of an atmospheric co-flow burner with resulting velocity oscillation amplitudes |u′/Uavg| in the 0.03–0.30 range. The dependence of flame dynamics on the relative richness of the flame is investigated by studying various constant fuel flow rate flame configurations. Flame heat release is quantitatively measured and simultaneously imaged using a photomultiplier (PMT) and a phase-locked CCD camera. Both of which are fitted with 430nm bandpass filters for observing CH*chemiluminescence. The flame response is observed to exhibit a low-pass filter characteristic with minimal flame response beyond pulsing frequencies of 200Hz. Flames at lower fuel flow rates are observed to remain attached to the central fuel pipe at all acoustic pulsing frequencies. PIV imaging of the associated isothermal fields show the amplification in flame aspect ratio is caused by the narrowing of the inner recirculation zone (IRZ). The Rayleigh criterion (R) is used to assess the potential for instability of specific perturbation configurations and is found to be a good predictor of unstable modes. Phase conditioned analysis of the flame dynamics yield additional criteria in highly responsive modes to include the effective amplitude of velocity oscillations induced by the acoustic pulsing. Highly amplified responses were observed in pulsed flame configurations with Strouhal numbers (St = fpUavg/dm) in the 1–3.5 range. Heat release to velocity perturbation time delays on the order of the acoustic pulsing period also characterized the highly responsive flames. Finally, wavelet analyses of heat release perturbations indicate sustained low frequency oscillations that become more prominent for low acoustic pulsing frequencies in lean flame configurations.}, number={PARTS A AND B}, booktitle={Proceedings of the ASME Turbo Expo}, author={Idahosa, U. and Saha, A. and Khatami, N. and Xu, C. and Basu, S.}, year={2010}, pages={1309–1321} }
 @misc{shao_xu_an_2010, title={Carbon Nanofiber Reinforced Polymer Derived Ceramic Nanocomposites}, author={Shao, G. and Xu, C. and An, L.}, year={2010} }
 @misc{joslin_hernandez_collins_giesecke_ji_xu_2010, title={Experimental Setup for Multi-sensor Fusion and Data Correlation Analysis during CNC Steel Turning Process}, author={Joslin, A. and Hernandez, M. and Collins, S. and Giesecke, D. and Ji, Y. and Xu, C.}, year={2010} }
 @inproceedings{joslin_hernandez_deane_collins_xu_wilson_2010, title={Experimental setup for multi-sensor fusion and data correlation analysis during CNC steel turning process}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82455174828&partnerID=MN8TOARS}, DOI={10.1115/MSEC2010-34308}, abstractNote={This paper discusses a preliminary setup for an ongoing research project with goals of off-line modeling and optimization for a CNC turning process of AISI 4137 steel alloy; followed by online monitoring, optimization, and control of the machining process. A full factorial Design Of Experiment (DOE) of three machining parameter factors was created in Minitab™ and Analysis of Variance was performed, in order to determine which parameters influenced the machining process the most. Accelerometers, acoustic emission sensors and force sensors have given researchers insights into the relationships between mechanical vibration and tool condition during the turning process. Similarly, correlations have been recognized between electrical power consumption, machining forces, tool temperature, and tool condition. While monitoring the machining process with sophisticated force and acceleration sensors is effective, implementation in a large scale factory environment may not be an economical solution to online monitoring and control. Finding an ideal combination of sensors capable of monitoring significant factors that affect the CNC steel turning process will allow process optimization and reduce the cost of machining.}, booktitle={ASME 2010 International Manufacturing Science and Engineering Conference, MSEC 2010}, author={Joslin, A. and Hernandez, M. and Deane, E. and Collins, S. and Xu, C. and Wilson, D.F.}, year={2010}, pages={461–467} }
 @article{yang_xu_wu_lin_chao_an_2010, title={Fabrication of AA6061/Al<inf>2</inf>O<inf>3</inf>nano ceramic particle reinforced composite coating by using friction stir processing}, volume={45}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77955471177&partnerID=MN8TOARS}, DOI={10.1007/s10853-010-4525-1}, number={16}, journal={Journal of Materials Science}, author={Yang, M. and Xu, C. and Wu, C. and Lin, K.-C. and Chao, Y.J. and An, L.}, year={2010}, pages={4431–4438} }
 @article{yang_gao_xu_wei_an_2010, title={Fabrication of Si3N4/SiC nanocomposites toughened by in-situ formed low-dimensional nanostructures}, volume={12}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77956056271&partnerID=MN8TOARS}, DOI={10.1016/j.solidstatesciences.2010.07.013}, abstractNote={We report the fabrication of Si3N4/SiC nano/nano-composite reinforced by single-crystal low-dimensional nanostructures via spark plasma sintering of nanocomposite powders containing in-situ formed Si3N4 nanowires/nanobelts. The fabricated nanocomposite is analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy and selective area electron diffraction. The results show that the in-situ formed Si3N4 nanowires/nanobelts are uniformly distributed within the matrix. Such a nanocomposite could exhibit improved mechanical properties, due to the superior mechanical properties and uniform distribution of the nano-reinforcements.}, number={9}, journal={Solid State Sciences}, author={Yang, W. and Gao, F. and Xu, C. and Wei, G. and An, L.}, year={2010}, pages={1692–1695} }
 @inproceedings{li_liu_xu_2010, title={Machinability study of SiC nano-particles reinforced Magnesium nanocomposites during micro-milling processes}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-82455186163&partnerID=MN8TOARS}, DOI={10.1115/MSEC2010-34294}, abstractNote={This paper experimentally investigates the machinability of Magnesium Metal Matrix Composites (Mg-MMCs) with high volume fractions of SiC nano-particles. Samples of Mg-MMCs with 5 Vol.%, 10 Vol.% and 15 Vol.% reinforcements of SiC nano-particles were studied and compared with pure Magnesium. Different feedrates and spindle speeds were chosen as varied cutting parameters. Cutting forces, surface morphology and roughness were measured to understand the machinability of the four different materials during the micro-milling process. Based on the experimental results, it is observed that the cutting force increases with the increase of the spindle speed, the feedrate and/or the volume fraction. A drastic increasing rate is observed when the nano-particles’ volume fraction is increased from 5 to 10 Vol.%. The effect of the volume fraction is also studied in frequency domain, combined with the effect of the spindle speed and feedrate. More detailed theoretical analysis will be further studied to better understand the effect of the volume fraction on the machined surface quality and machining productivity.}, booktitle={ASME 2010 International Manufacturing Science and Engineering Conference, MSEC 2010}, author={Li, J. and Liu, J. and Xu, C.}, year={2010}, pages={391–398} }
 @article{jiang_hill_fei_wei_tellam_xu_an_2010, title={Making bulk ceramics from polymeric precursors}, volume={93}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649544025&partnerID=MN8TOARS}, DOI={10.1111/j.1551-2916.2010.04069.x}, abstractNote={In this paper, we report a simple technique for making bulk Si-based ceramics from polymeric precursor. In this technique, a porous polymer preform with high porosity is used as a template. The preform is thermally decomposed before the precursor during pyrolysis to form interconnected pores for releasing gaseous species resulting from pyrolysis of precursors to avoid the formation of cracks within resultant ceramics. The thermal decomposition behavior of both template and precursor is studied for determining the proper pyrolysis procedure. The microstructure, porosity, and mechanical strength of the ceramics obtained are characterized.}, number={10}, journal={Journal of the American Ceramic Society}, author={Jiang, T. and Hill, A. and Fei, W. and Wei, Y. and Tellam, M. and Xu, C. and An, L.}, year={2010}, pages={3017–3019} }
 @inproceedings{liu_xu_an_2010, title={Micro-machinable polymer-derived ceramic sensors for high-temperature applications}, volume={7647}, url={http://dx.doi.org/10.1117/12.848529}, DOI={10.1117/12.848529}, abstractNote={Micro-sensors are highly desired for on-line temperature/pressure monitoring in turbine engines to improve their efficiency and reduce pollution. The biggest challenge for developing this type of sensors is that the sensors have to sustain at extreme environments in turbine engine environments, such as high-temperatures (>800 &deg;C), fluctuated pressure and oxidation/corrosion surroundings. In this paper, we describe a class of sensors made of polymer-derived ceramics (PDCs) for such applications. PDCs have the following advantages over conventional ceramics, making them particularly suitable for these applications: (i) micromachining capability, (ii) tunable electric properties, and (iii) hightemperature capability. Here, we will discuss the materials and their properties in terms of their applications for hightemperature micro-sensors, and microfabrication technologies. In addition, we will also discuss the design of a heat-flux sensor based on polymer-derived ceramics.}, booktitle={Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2010}, publisher={SPIE}, author={Liu, Jian and Xu, Chengying and An, Linan}, editor={Tomizuka, MasayoshiEditor}, year={2010}, month={Mar} }
 @article{idahosa_saha_xu_basu_2010, title={Non-premixed acoustically perturbed swirling flame dynamics}, volume={157}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77954386686&partnerID=MN8TOARS}, DOI={10.1016/j.combustflame.2010.05.008}, abstractNote={An investigation into the response of non-premixed swirling flames to acoustic perturbations at various frequencies (fp = 0–315 Hz) and swirl intensities (S = 0.09 and 0.34) is carried out. Perturbations are generated using a loudspeaker at the base of an atmospheric co-flow burner with resulting velocity oscillation amplitudes |u′/Uavg| in the 0.03–0.30 range. The dependence of flame dynamics on the relative richness of the flame is investigated by studying various constant fuel flow rate flame configurations. Flame heat release rate is quantitatively measured using a photomultiplier with a 430 nm bandpass filter for observing CH∗ chemiluminescence which is simultaneously imaged with a phase-locked CCD camera. The flame response is observed to exhibit a low-pass filter characteristic with minimal flame response beyond pulsing frequencies of 200 Hz. Flames at lower fuel flow rates are observed to remain attached to the central fuel pipe at all acoustic pulsing frequencies. PIV imaging of the associated isothermal fields show the amplification in flame aspect ratio is caused by the narrowing of the inner recirculation zone (IRZ). Good correlation is observed between the estimated flame surface area and the heat release rate signature at higher swirl intensity flame configurations. A flame response index analogous to the Rayleigh criterion in non-forced flames is used to assess the potential for a strong flame response at specific perturbation configurations and is found to be a good predictor of highly responsive modes. Phase conditioned analysis of the flame dynamics yield additional criteria in highly responsive modes to include the effective amplitude of velocity oscillations induced by the acoustic pulsing. In addition, highly responsive modes were characterized by velocity to heat release rate phase differences in the ±π/2 range. A final observed characteristic in highly responsive flames is a Strouhal number between 1 and 3.5 based on the burner co-flow annulus diameter (St = fpUavg/dm). Finally, wavelet analyses of heat release rate perturbations indicate highly responsive modes are characterized by sustained low frequency oscillations which accompany the high amplitude velocity perturbations at these modes. Higher intensity low frequency heat release rate oscillations are observed for lean flame/low pulsing frequency conditions.}, number={9}, journal={Combustion and Flame}, author={Idahosa, U. and Saha, A. and Xu, C. and Basu, S.}, year={2010}, pages={1800–1814} }
 @article{tang_xu_2010, title={Online Tool Deflection Compensation in End Milling of Curved Workpiece}, volume={1}, number={1}, journal={International Journal of Electronics, Computing and Engineering Education}, author={Tang, Y. and Xu, C.}, year={2010}, pages={23–28} }
 @article{sarkar_zou_liu_xu_an_zhai_2010, title={Polymer-derived ceramic composite fibers with aligned pristine multiwalled carbon nanotubes}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77953716483&partnerID=MN8TOARS}, DOI={10.1021/am1000085}, abstractNote={Polymer-derived ceramic fibers with aligned multiwalled carbon nanotubes (MWCNTs) are fabricated through the electrospinning of polyaluminasilazane solutions with well-dispersed MWCNTs followed by pyrolysis. Poly(3-hexylthiophene)-b-poly (poly (ethylene glycol) methyl ether acrylate) (P3HT-b-PPEGA), a conjugated block copolymer compatible with polyaluminasilazane, is used to functionalize MWCNT surfaces with PPEGA, providing a noninvasive approach to disperse carbon nanotubes in polyaluminasilazane chloroform solutions. The electrospinning of the MWCNT/polyaluminasilazane solutions generates polymer fibers with aligned MWCNTs where MWCNTs are oriented along the electrospun jet by a sink flow. The subsequent pyrolysis of the obtained composite fibers produces ceramic fibers with aligned MWCNTs. The study of the effect of polymer and CNT concentration on the fiber structures shows that the fiber size increases with the increment of polymer concentration, whereas higher CNT content in the polymer solutions leads to thinner fibers attributable to the increased conductivity. Both the SEM and TEM characterization of the polymer and ceramic fibers demonstrates the uniform orientation of CNTs along the fibers, suggesting excellent dispersion of CNTs and efficient CNT alignment via the electrospinning. The electrical conductivity of a ceramic fibers with 1.2% aligned MWCNTs is measured to be 1.58 x 10(-6) S/cm, which is more than 500 times higher than that of bulk ceramic (3.43 x 10(-9) S/cm). Such an approach provides a versatile method to disperse CNTs in preceramic polymer solutions and offers a new approach to integrate aligned CNTs in ceramics.}, number={4}, journal={ACS Applied Materials and Interfaces}, author={Sarkar, S. and Zou, J. and Liu, J. and Xu, C. and An, L. and Zhai, L.}, year={2010}, pages={1150–1156} }
 @inproceedings{allen_lin_xu_2010, title={Robust estimation of a maneuvering target from multiple unmanned air vehicles' measurements}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77954470508&partnerID=MN8TOARS}, DOI={10.1109/CTS.2010.5478465}, abstractNote={When multiple UAVs collaborate to track a maneuvering target, their position measurement sensors are sometimes corrupted by noise biases (e.g. sensor drifting). In this case, the zero-mean noise assumption of the Kalman filter is therefore violated and the desired optimal estimate will not be guaranteed. In this paper, an H-infinity filter is utilized to estimate the position of the maneuvering target to compensate for non-zero-mean noise. Furthermore, the constrained H-infinity filter is shown to be superior to the Kalman filter.}, booktitle={2010 International Symposium on Collaborative Technologies and Systems, CTS 2010}, author={Allen, R. and Lin, K.-C. and Xu, C.}, year={2010}, pages={537–545} }
 @inproceedings{sarkar_zou_xu_an_zhai_2010, title={SiCN ceramic fibers with aligned carbon nanotubes}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-78649483096&partnerID=MN8TOARS}, booktitle={International SAMPE Symposium and Exhibition (Proceedings)}, author={Sarkar, S. and Zou, J. and Xu, C. and An, L. and Zhai, L.}, year={2010} }
 @inproceedings{joslin_xu_2009, title={A hybrid modeling technique for partially-known systems using linear regression and neural network}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77953224712&partnerID=MN8TOARS}, DOI={10.1115/MSEC2009-84217}, abstractNote={In this paper a hybrid modeling and system identification method, combining linear least squares regression and artificial neural network techniques, is presented to model a type of dynamic systems which have an incomplete analytical model description. This approach in modeling nonlinear, partially-understood systems is particularly useful to the study of manufacturing processes, where the linear regression portion of the hybrid model is established using a known mathematical model for the process and the neural network is constructed using the residuals from the least squares regression, therefore ensuring a more precise process model for the specific machining setup, tooling selection, workpiece properties, etc. In this paper the method is mathematically proven to give regression coefficients close to those which would be found if only a regression had been performed. The modeling method is then simulated for a macro-scale hard turning process, and the result proves the effectiveness of the proposed hybrid modeling method.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference 2009, MSEC2009}, author={Joslin, A.J. and Xu, C.}, year={2009}, pages={365–375} }
 @article{jackson_xu_ahmed_2009, title={A multifunctional high-speed spindle for micromachining medical materials}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-73549119972&partnerID=MN8TOARS}, DOI={10.1504/IJNBM.2009.028341}, abstractNote={The efficiency of micro cutting tools that are used in high-speed air turbine spindles depends on the rotational speed of the rotor, especially when machining medical materials such as titanium alloys. A high-pressure variation on the surface of the rotor causes the rotor to retard and this severely limits the reliability and durability of high-speed spindles to support new developments in the developing area of micromachining. A variety of spindle designs are proposed and numerical simulations carried out for each design using FLUENT software. The results revealed that changes in the rotor, inlet and outlet geometries affect the pressure distribution on the rotor significantly. The optimum design was identified based on the lowest pressure variation on the rotor surface obtained from the FLUENT results. Spinning the rotor at very high speeds provides a new direction in the development of mechanical micromachining.}, number={6}, journal={International Journal of Nano and Biomaterials}, author={Jackson, M.J. and Xu, C. and Ahmed, W.}, year={2009}, pages={520–539} }
 @article{xu_shin_2009, title={A stable hierarchical fuzzy control design for certain non-linear systems based on input-output passivity theory}, volume={37}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-69949109741&partnerID=MN8TOARS}, number={2}, journal={Control and Intelligent Systems}, author={Xu, C. and Shin, Y.C.}, year={2009}, pages={103–113} }
 @article{tang_xu_jackson_2009, title={Adaptive compensation of tool deflection in micromilling processes}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-68149149709&partnerID=MN8TOARS}, DOI={10.1504/IJNM.2009.027056}, abstractNote={This paper proposed a novel adaptive control method to compensate the cutting force induced tool deflection during micromilling processes. Owing to the slenderness of the micromilling cutter, the tool deflects at a certain degree depending on the magnitude of the instantaneous cutting force. The proposed intelligent adaptive control algorithm will adjust the cutting conditions online to compensate the tool deflection and therefore improving the machining accuracy. The numerical simulation results demonstrate the effectiveness of the proposed compensation strategy.}, number={1-2}, journal={International Journal of Nanomanufacturing}, author={Tang, Y. and Xu, C. and Jackson, M.J.}, year={2009}, pages={159–168} }
 @inproceedings{idahosa_saha_xu_basu_2009, title={Characterization of combustion dynamics in swirl stabilized flames}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77952897544&partnerID=MN8TOARS}, DOI={10.1115/POWER2009-81168}, abstractNote={This paper investigates flame frequency response relative to changes in swirl intensity and equivalence ratio in a non-premixed swirl stabilized burner. The degree of swirl in the burner is characterized by the swirl number (S) provided by circumferentially distributed air supply ports directed tangentially to the main axial air flow. Equivalence ratio variations are induced using varying constant, linear ramp and exponentially decaying fuel (propane) flow rates towards blowoff. The variations in the air speed at the exit of the burner (U) are measured with an anemometer located at the base of the flame. The emission of CH* radicals (I) is used as a marker of flame heat release and is measured using a photomultiplier (PMT). The frequency response of the PMT heat release and burner velocity signals are analyzed in the frequency domain using the Fast Fourier Transform (FFT) and Continuous Wavelet Transform (CWT) methods. Amplification in the power of heat release fluctuation is observed in low swirl flames close to blowoff. This effect is found to be reversed in higher swirl number flames even close to blowoff. In dynamic approaches to blowoff (using ramp and decaying fuel flow rates), the dominant heat release fluctuation frequencies are observed to be similar to perturbation frequencies in lean flames hovering at constant fuel flow rates close to blowoff.}, booktitle={American Society of Mechanical Engineers, Power Division (Publication) PWR}, author={Idahosa, U. and Saha, A. and Xu, C. and Basu, S.}, year={2009}, pages={517–531} }
 @article{jackson_whitfield_xu_ahmed_2009, title={Diamond coated microtools for machining compact bone}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-73549097118&partnerID=MN8TOARS}, DOI={10.1504/IJNBM.2009.028340}, abstractNote={The structure of compact bone is heterogeneous and as such, is difficult to shape by cutting tools during clinical surgical practices. The structure of bone can have a devastating effect on the performance of the cutting tool unless it is coated with a thin solid film that is wear resistant. The paper investigates the use of diamond coated cutting tools to prepare bone for prosthetic implants and the implications of their use on the machining characteristics of biological materials.}, number={6}, journal={International Journal of Nano and Biomaterials}, author={Jackson, M.J. and Whitfield, M.D. and Xu, C. and Ahmed, W.}, year={2009}, pages={505–519} }
 @inproceedings{nicholson_liu_qiu_mak_trinh_xu_vaidyanathan_2009, title={Fabrication and Thermo-Mechanical Testing of a High Temperature Shape Memory Alloy Helical Actuator}, author={Nicholson, D. and Liu, J. and Qiu, S. and Mak, A. and Trinh, J. and Xu, C. and Vaidyanathan, R.}, year={2009} }
 @inproceedings{idahosa_abhishek_joslin_basu_xu_2009, place={Orlando, FL}, title={Flame Response to Equivalence Ratio Oscillations in Perturbed Swirl Stabilized Flames}, booktitle={ASME Turbo Expo 2009 - Combustion Dynamics}, author={Idahosa, U. and Abhishek, S. and Joslin, A. and Basu, S. and Xu, C.}, year={2009} }
 @inbook{jackson_evans_xu_ahmed_2009, title={Formation of Nanostructured Metals}, booktitle={Machining with Nanomaterials}, publisher={Springer}, author={Jackson, M.J. and Evans, J. and Xu, C. and Ahmed, W.}, year={2009} }
 @inproceedings{idahosa_saha_xu_basu_2009, place={Ann Arbor, MI}, title={Frequency Response Characterization of Swirl Stabilized Flames Dynamics}, booktitle={Proceedings of the 6th US National Combustion Meeting of the Combustion Institute}, author={Idahosa, U. and Saha, A. and Xu, C. and Basu, S.}, year={2009} }
 @inbook{jackson_ahmed_xu_2009, title={Fundamentals of Machining}, booktitle={Machining with Nanomaterials}, publisher={Springer}, author={Jackson, M.J. and Ahmed, W. and Xu, C.}, year={2009} }
 @inproceedings{shamieh_xu_2009, title={Generation of optimal functions using particle swarm method over discrete intervals}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-70350402296&partnerID=MN8TOARS}, DOI={10.1109/NAFIPS.2009.5156484}, abstractNote={Particle swarm optimization is a computational learning technique designed to find a global and optimal solution upon or within a function. The output, usually singular, is characteristically accurate as the nature of the system is to maintain a balance of convergence and sample diversity. This paper aims to introduce the process of using a multi-level evaluation approach of particle swarm optimization to generate a solution function. Multiple variable assessment is replaced with sequential interval assessment of repeated variables and pieced together to form the framework of an optimized function.}, booktitle={Annual Conference of the North American Fuzzy Information Processing Society - NAFIPS}, author={Shamieh, F. and Xu, C.}, year={2009} }
 @inproceedings{tang_xu_jackson_2009, title={Geometrical adaptive controller for tool deflection compensation in helical end milling processes}, volume={2}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77953211980&partnerID=MN8TOARS}, DOI={10.1115/MSEC2009-84218}, abstractNote={Geometrical Adaptive Control (GAC) aims to maintain the stability of the geometrical quality of mechanical parts during production. GAC systems can effectively compensate for the machining error induced by cutter deflection during helical end milling processes. The existing GAC systems only deal with deflection compensation in machining of straight surfaces. Deflection in curved surface machining is more complicated, and the effect of surface curvature on deflection should be considered when designing the GAC compensation system. This paper intends to develop a GAC system for cutter deflection in end milling of curved geometries to account for deflection variation induced by workpiece curvature. In this paper, the influence of curved geometry on cutting forces is firstly analyzed; then, the deflection is calculated based on the cantilever beam model. The error space motion control methodology is utilized in GAC design for deflection compensation. Simulation studies are conducted on a two-axis milling system for circular surface, and the results validate the compensation strategy.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference 2009, MSEC2009}, author={Tang, Y. and Xu, C. and Jackson, M.}, year={2009}, pages={377–383} }
 @inproceedings{idahosa_khatami_saha_xu_basu_2009, title={On the fluid dynamics of acoustically perturbed non-premixed swirling flames}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84946594823&partnerID=MN8TOARS}, booktitle={Fall Meeting of the Eastern States Section of the Combustion Institute 2009}, author={Idahosa, U. and Khatami, N. and Saha, A. and Xu, C. and Basu, S.}, year={2009}, pages={720–725} }
 @inbook{xu_2009, title={Persistence, Consistence and Patience}, booktitle={Tips on Getting an Academic Position}, publisher={Lulu Web}, author={Xu, C.}, year={2009} }
 @article{xu_tang_jackson_2009, title={Survey on various control techniques in micro grinding processes}, volume={3}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-68649101216&partnerID=MN8TOARS}, DOI={10.1504/IJNM.2009.027503}, abstractNote={Due to the highly demanding geometric accuracy and surface finish for many modern products, grinding processes have been extensively used in manufacturing industry. However, it is also well accepted that grinding is one of the most complicated machining processes due to the high non-linearities, intrinsic uncertainties and time-varying characteristics. Multiple challenging problems exist in the process that limits its overall quality and production in practice. With the increasing demands for higher part geometry accuracy, better surface integrity, more productivity and other desired product parameters (e.g., minimisation of subsurface micro-damage) with less operator intervention, various control methods have been studied and implemented to control position, velocity, force, power, temperature and the material removal rate (MRR) during the grinding process, in order to achieve the desired system performance within certain cost/time. This paper reviews different control strategies in order to provide a guideline for academic researchers and industrial practitioners in improving the final product quality with increased possible process flexibility.}, number={4}, journal={International Journal of Nanomanufacturing}, author={Xu, C. and Tang, Y. and Jackson, M.J.}, year={2009}, pages={398–408} }
 @article{xu_shin_2008, title={A fuzzy inverse model construction method for general monotonic multi-input-single-output (MISO) systems}, volume={16}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-54349120075&partnerID=MN8TOARS}, DOI={10.1109/TFUZZ.2008.924336}, abstractNote={This paper presents a novel method of systematically constructing a fuzzy inverse model for general multi-input-single-output (MISO) systems represented with triangular input membership functions, singleton output membership function, and fuzzy-mean defuzzification. The fuzzy inverse model construction method has the ability of uniquely determining the inverse relationship for each input-output pair. It is derived in a straightforward way and the required input variables can be simultaneously obtained by the fuzzy inferencing calculation to realize the desired output value. Simulation examples are provided to demonstrate the effectiveness of the proposed method to find the inverse kinematics solutions for complex multiple degree-of-freedom industrial robot manipulators.}, number={5}, journal={IEEE Transactions on Fuzzy Systems}, author={Xu, C. and Shin, Y.C.}, year={2008}, pages={1216–1231} }
 @inproceedings{xu_shin_2008, title={A multi-level fuzzy control design for general nonlinear multi-input single-output systems}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-51149121226&partnerID=MN8TOARS}, DOI={10.1109/NAFIPS.2008.4531229}, abstractNote={In this paper, an adaptive fuzzy controller is developed for general multi-input single-output (MISO) nonlinear systems with time-varying characteristics and unknown system uncertainties. The system dynamics is modeled in fuzzy domain and the fuzzy inverse model is automatically constructed, which has the ability of uniquely determining the inverse relationship for each input-output pair. Based on this inverse model, a multi-level fuzzy controller (MLFC) is designed with embedded hierarchical structure for each control variable to compensate for system uncertainties and time-varying parameters. A set of simulation examples are presented to illustrate the effectiveness of the proposed controller for the multivariable systems under various operating conditions.}, booktitle={Annual Conference of the North American Fuzzy Information Processing Society - NAFIPS}, author={Xu, C. and Shin, Y.C.}, year={2008} }
 @misc{xu_tang_jackson_2008, title={Adaptive Control of Cutting Force to Compensate Tool Deflection during Micro-Milling Processes}, author={Xu, C. and Tang, Y. and Jackson, M.}, year={2008} }
 @article{xu_shin_2008, title={An adaptive fuzzy controller for constant cutting force in end-milling processes}, volume={130}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-49749152386&partnerID=MN8TOARS}, DOI={10.1115/1.2823070}, abstractNote={A novel multilevel fuzzy control system is introduced and implemented for online force control of end-milling processes to increase machining productivity and improve workpiece quality, where the cutting force is maintained at its maximum allowable level in the presence of different variations inherent in milling processes, such as tool wear, workpiece geometry, and material properties. In the controller design, the fuzzy rules are generated heuristically without any mathematical model of the milling processes. An adaptation mechanism is embedded to tune the control parameters online, and the resultant closed-loop system is guaranteed to be stable based on the input-output passivity analysis. In the experiment, the control algorithm is implemented using a National Instrument real-time control computer in an open architecture control environment, where high metal removal rates are achieved and the cycle time is reduced by up to 34% over the case without any force controller and by 22% compared with the regular fuzzy logic controller, thereby indicating its effectiveness in improving productivity for actual machining processes.}, number={3}, journal={Journal of Manufacturing Science and Engineering, Transactions of the ASME}, author={Xu, C. and Shin, Y.C.}, year={2008}, pages={0310011–03100110} }
 @article{r._xu_2008, title={Cooperative Navigation and Adaptive Guidance}, volume={41}, number={4}, journal={The Bulletin of Military Operations Research: Phalanx}, author={R., Allen and Xu, C.}, year={2008}, pages={12–17} }
 @misc{xu_knipe_jackson_2008, title={Finite Element Modeling and Vibration Control of a Tetraform Space Frame for Micro-Machining Processes}, author={Xu, C. and Knipe, K. and Jackson, M.}, year={2008} }
 @article{knipe_xu_jackson_2008, title={Finite element modelling and vibration control of a tetrahedral space frame applied to micromachining}, volume={1}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77953518026&partnerID=MN8TOARS}, DOI={10.1504/IJNBM.2008.022872}, abstractNote={This paper presents the modelling and vibration control of the tetrahedral space frame. The tetrahedral frame is a structure that is used in precision machining applications. When machining at a high precision requirement, structural vibration is of the utmost concern. This research develops finite element models using ANSYS and Matlab that can be used to implement a positive position feedback controller. In order to control and reduce the vibration magnitude, collocated piezoelectric actuators and sensors are placed at the optimal positions on the tetrahedral space frame. ANSYS is used to conduct a modal analysis on the structure to obtain the mode shapes, which determines the weakest positions and critical vibration modes under certain machining conditions. In Matlab, a finite element model is created which uses Timoshenko's beam elements and it is further converted to state-space allowing the model to be controlled using programme simulations. A positive position feedback controller is chosen due to its non-sensitivity to spillover effects.}, number={4}, journal={International Journal of Nano and Biomaterials}, author={Knipe, K. and Xu, C. and Jackson, M.J.}, year={2008}, pages={448–458} }
 @book{shin_xu_2008, title={Intelligent Systems: Modeling, Optimization and Control}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85052533159&partnerID=MN8TOARS}, DOI={10.1201/9781420051773}, abstractNote={Providing a thorough introduction to the field of soft computing techniques, Intelligent Systems: Modeling, Optimization, and Control covers every major technique in artificial intelligence in a clear and practical style. This book highlights current research and applications, addresses issues encountered in the development of applied systems, and describes a wide range of intelligent systems techniques, including neural networks, fuzzy logic, evolutionary strategy, and genetic algorithms. The book demonstrates concepts through simulation examples and practical experimental results. Case studies are also presented from each field to facilitate understanding.}, journal={Intelligent Systems: Modeling, Optimization, and Control}, publisher={CRC Press, Taylor & Francis}, author={Shin, Y.C. and Xu, C.}, year={2008}, pages={1–433} }
 @inproceedings{xu_shin_2007, title={A fuzzy inverse model construction method for a general MISO system with a monotonie input-output relationship}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-35148860671&partnerID=MN8TOARS}, DOI={10.1109/NAFIPS.2007.383801}, abstractNote={This paper presents a novel method of systematically constructing the fuzzy inverse model for a general multi-input single-output (MISO) system represented with triangular input membership functions, singleton output membership function and fuzzy-mean defuzzification. The fuzzy inverse model construction method has the ability of uniquely determining the inverse relationship for each input-output pair. It is derived in a straightforward way and the required input variables can be simultaneously obtained by the fuzzy inferencing calculation to realize the desired output value. Simulation examples are provided to demonstrate the effectiveness of the proposed method to find the inverse kinematics solutions for complex industrial robot manipulators.}, booktitle={Annual Conference of the North American Fuzzy Information Processing Society - NAFIPS}, author={Xu, C. and Shin, Y.C.}, year={2007}, pages={1–6} }
 @article{xu_shin_2007, title={Control of cutting force for creep-feed grinding processes using a multi-level fuzzy controller}, volume={129}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34547755769&partnerID=MN8TOARS}, DOI={10.1115/1.2718238}, abstractNote={In this paper, a multi-level fuzzy control (MLFC) technique is developed and implemented for a creep-feed grinding process. The grinding force is maintained at the maximum allowable level under varying depth of cut, so that the highest metal removal rate is achieved with a good workpiece surface quality. The control rules are generated heuristically without any analytical model of the grinding process. Based on the real-time force measurement, the control parameters are adapted automatically within a stable range. A National Instrument real-time control computer is implemented in an open architecture control system for the grinding machine. Experimental results show that the cycle time has been reduced by up to 25% over those without force control and by 10–20% compared with the conventional fuzzy logic controller, which indicates its effectiveness in improving the productivity of actual manufacturing processes. The effect of grinding wheel wear is also considered in the creep-feed grinding process, where the grinding force/power can be maintained around the specified value by the proposed MLFC controller as the wheel dulls gradually.}, number={4}, journal={Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME}, author={Xu, C. and Shin, Y.C.}, year={2007}, pages={480–492} }
 @misc{xu_2007, title={Intelligent Control System for Manufacturing Processes}, author={Xu, C.}, year={2007} }
 @article{xu_shin_2007, title={Interaction analysis for MIMO nonlinear systems based on a fuzzy basis function network model}, volume={158}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34447291370&partnerID=MN8TOARS}, DOI={10.1016/j.fss.2007.02.012}, abstractNote={This paper describes an interaction analysis method for a general multi-input multi-output (MIMO) nonlinear system based on its fuzzy rule-based model. Most real-world multivariable systems are nonlinear, complex and time varying. The multiple system input-output variables interact and sometime even fight against each other, causing significant challenges for system control and optimization. Especially in many practical applications, the accurate quantitative system model is not available or difficult to obtain, which subsequently makes it impossible to analyze the system multivariable interaction characteristics. In this paper, the nonlinear MIMO system is first modeled by fuzzy basis function networks (FBFN) based on a set of linguistic IF-THEN rules or data. The multivariable interaction property is analyzed locally around the operating point based on the relative gain Array (RGA), which is systematically formulated using the system steady-state gain values. Two simulation examples of chemical distillation columns illustrate the system interaction degree obtained by the proposed method is in a sufficient accuracy compared with the result calculated from the system explicit mathematical model, which indicates the applicability of the proposed method as an alternative way to derive the system multivariable interaction when the system mathematical model is not available.}, number={18}, journal={Fuzzy Sets and Systems}, author={Xu, C. and Shin, Y.C.}, year={2007}, pages={2013–2025} }
 @inproceedings{xu_shin_2006, title={A Hierarchical Self-tuning Fuzzy Controller for General Nonlinear Systems with Stability Analysis}, author={Xu, C. and Shin, Y.C.}, year={2006} }
 @inproceedings{xu_shin_2006, title={Adaptive Control of Cutting Force for End Milling Processes with System Variation using Self-tuning Fuzzy Technique}, author={Xu, C. and Shin, Y.C.}, year={2006} }
 @inproceedings{xu_shin_2006, title={An adaptive fuzzy controller for constant cutting force in end-milling processes}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84920631460&partnerID=MN8TOARS}, DOI={10.1115/IMECE2006-13758}, abstractNote={A novel multi-level fuzzy control (MLFC) system is introduced and implemented for online force control of end-milling processes to increase machining productivity and improve workpiece quality, where the cutting force is maintained at its maximum allowable level in the presence of different variations inherent in milling processes, such as tool wear, workpiece geometry and material properties. In the controller design, the fuzzy rules are generated heuristically without any mathematical model of the milling processes. An adaptation mechanism is embedded in to tune the control parameters on-line and the resultant closed-loop system is guaranteed to be stable based on the input-output passivity analysis. In the experiment, the control algorithm is implemented using a National Instrument real-time control computer in an open architecture control environment, where high metal removal rates (MRR) are achieved and the cycle time is reduced by up to 34% over the case without any force controller, and by 22% compared with the regular fuzzy logic controller (FLC), thereby indicating its effectiveness in improving the productivity for actual machining processes.}, booktitle={American Society of Mechanical Engineers, Dynamic Systems and Control Division (Publication) DSC}, author={Xu, C. and Shin, Y.C.}, year={2006} }
 @article{xu_shin_2005, title={Design of a multilevel fuzzy controller for nonlinear systems and stability analysis}, volume={13}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-30344443968&partnerID=MN8TOARS}, DOI={10.1109/TFUZZ.2005.859308}, abstractNote={In this paper, a multilevel fuzzy control (MLFC) system is developed and implemented to deal with the real-world nonlinear plants with intrinsic uncertainties and time-varying parameters. The proposed fuzzy control strategy has a hierarchical structure with an adaptation mechanism embedded in the lower level to tune the output membership functions (MFs) of the first layer fuzzy controller and can be used to control a system with an input-output monotonic relationship or a piecewise monotonic relationship. The stability of the closed-loop system under the proposed MLFC is theoretically proven. Simulations are carried out by applying the proposed multilevel fuzzy control (MLFC) to a uncertain nonlinear plants, and it is shown that much better system performances are achieved compared with conventional fuzzy logic controllers (FLC), even in presence of disturbance and noise.}, number={6}, journal={IEEE Transactions on Fuzzy Systems}, author={Xu, C. and Shin, Y.C.}, year={2005}, pages={761–778} }
 @article{xu_huan_2001, title={An Automatic Monitoring System on the Fault Diagnosis of NC machine Based on Internet Explorer}, volume={4}, journal={Mechanical Engineer}, author={Xu, C. and Huan, J.}, year={2001}, pages={21–23} }