Guo Y.,Tianjin University of Technology |
Ma W.,Tianjin University of Technology |
Zhang F.,Materials and Aerospace Engineering |
Zhang F.,Wanger Institute for Sustainable Energy Research
Journal of Materials Science: Materials in Electronics | Year: 2016
In this work Pb(Sb1/2Nb1/2)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr, Ti)O3 (PSN–PNN–PZT) ceramics were prepared by a conventional mixed oxide method. The morphotropic phase boundaries (MPBs) of yPSN–0.3PNN–(0.7 − y)PZT (y = 0, 0.005, 0.01, 0.015 and 0.02) ceramics with a variable PSN were investigated. The MPB compositions, possessing high performances, were identified using X-ray diffraction and further confirmed by their piezoelectric/dielectric properties. The MPBs shifted to a PT-rich region as PSN increased. The optimal electric properties of 0.015PSN–0.3PNN–0.685PZT were found to be d33 = 660pC/N, kp = 0.68, ε33 T/ε0 = 4279, tan δ = 1.56 % for the MPB composition. The remanent polarizations and poling strain gradually increased and then decreased as the PSN content increased. The remanent polarizations (Pr) and poling strains of 0.015PSN–0.3PNN–0.685PZT ceramics at MPB were 33.5 μC/cm2 and 0.39 %, respectively. Furthermore, the electrical performances were also related to the cooling speed in the poling process, where the poling field was 3 kV/mm, the poling temperature was 120 °C and the poling time was 15 min. © 2015, Springer Science+Business Media New York.
Wang C.,Materials and Aerospace Engineering |
Wang C.,Wanger Institute for Sustainable Energy Research |
Sawicki M.,Materials and Aerospace Engineering |
Sawicki M.,Wanger Institute for Sustainable Energy Research |
And 3 more authors.
Journal of the Electrochemical Society | Year: 2015
Na3MnCO3PO4 with a potential to deliver two-electron transfer reactions per formula via Mn2+/Mn3+ and Mn3+/Mn4+ redox reactions and a high theoretical capacity (191 mAh/g) can play an important role in Na-ion batteries. This study investigates the dependence of the electrochemical performance of Na3MnCO3PO4-based sodium-ion batteries on processing, structural defects and ionic conductivity. Na3MnCO3PO4 has been synthesized via hydrothermal process under various conditions with and without subsequent high-energy ball milling. Particle sizes, structural defects and ionic conductivity have been studied as a function of processing conditions. It is found that Na3MnCO3PO4 nanoparticles (20 nm in diameter) can be produced from hydrothermal synthesis, but the reaction time is critical in obtaining nanoparticles. Nanoparticles exhibit a higher ionic conductivity than agglomerated particles. Further, structural defects also have a strong influence on ionic conductivity which, in turn, affects the charge/discharge capacities of the Na3MnCO3PO4-based sodium-ion batteries. These results provide guidelines for rational design and synthesis of high capacity Na3MnCO3PO4 for Na-ion batteries in the near future. © The Author(s) 2015.
Woodburn D.A.,University of Central Florida |
Wu T.,University of Central Florida |
Chow L.,Materials and Aerospace Engineering |
Leland Q.,Air Force Research Lab |
And 6 more authors.
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2010
All-electric aircraft is a high priority goal in the avionics community. Both increased reliability and efficiency are the promised implications of this move. But, thermal management has become a significant issue that must be resolved before reaching this goal. Advanced analysis technologies such as finite element method and intelligent control systems such as field oriented control are being used to better understand the source of the heat and to eliminate as much of it as possible. This paper addresses the motivation behind all-electric aircraft and gives an overview of some of the considerations in cooling, simulation and modeling, and control, with an example of one control scheme which is being developed. © 2010 by the American Institute of Aeronautics and Astronautics, Inc.
Osorio A.F.,Materials and Aerospace Engineering |
Kassab A.J.,Materials and Aerospace Engineering |
Divo E.A.,University of Central Florida |
Argueta-Morales R.,Congenital Heart Institute at Arnold Palmer Hospital |
DeCampli W.M.,Congenital Heart Institute at Arnold Palmer Hospital
ASME International Mechanical Engineering Congress and Exposition, Proceedings | Year: 2010
Presently, mechanical support is the most promising alternative to cardiac transplantation. Ventricular Assist Devices (VADs) were originally used to provide mechanical circulatory support in patients waiting planned heart transplantation ("bridge-to-transplantation" therapy). The success of short-term bridge devices led to clinical trials evaluating the clinical suitability of long-term support ("destination" therapy) with left ventricular assist devices (LVADs). The first larger-scale, randomized trial that tested long-term support with a LVAD reported a 44% reduction in the risk of stroke or death in patients with a LVAD. In spite of the success of LVADs as bridge-to-transplantation and long-term support. Patients carrying these devices are still at risk of several adverse events. The most devastating complication is caused by embolization of thrombi formed within the LVAD or inside the heart into the brain. Prevention of thrombi formation is attempted through anticoagulation management and by improving LVADs design; however there is still significant occurrence of thromboembolic events in patients. Investigators have reported that the incidence of thromboembolic cerebral events ranges from 14% to 47% over a period of 6-12 months. An alternative method to reduce the incidence of cerebral embolization has been proposed by one of the co-authors, namely William DeCampli M.D., Ph.D. The hypothesis is that it is possible to minimize the number of thrombi flowing into the carotid arteries by an optimal placement of the LVAD outflow conduit, and/or the addition of aortic bypass connecting the ascending aorta (AO) and the innominate artery (IA), or left carotid artery (LCA). This paper presents the computational fluid dynamics (CFD) analysis of the aortic arch hemodynamics using a representative geometry of the human aortic arch and an alternative aortic bypass. The alternative aortic bypass is intended to reduce thrombi flow incidence into the carotid arteries in patients with LVAD implants with the aim to reduce thromboembolisms. In order to study the trajectory of the thrombi within the aortic arch, a Lagrangian particle-tracking model is coupled to the CFD model. Results are presented in the form of percentage of thrombi flowing to the carotid arteries as a function of LVAD conduit placement and aortic bypass implantation, revealing promising improvement. Copyright © 2010 by ASME.
Ding Z.,Materials and Aerospace Engineering |
Ding Z.,Illinois Institute of Technology |
Zhao X.,Materials and Aerospace Engineering |
Zhao X.,Illinois Institute of Technology |
And 2 more authors.
Journal of Power Sources | Year: 2015
Abstract Previous studies of ab initio density functional theory (DFT) calculations have predicted that reactions between LiBH4 and MgH2 can take place at temperature near 200°C. However, such predictions have been shown to be inconsistent with many experiments. Herein, we have designed a novel process termed as ball milling with aerosol spraying (BMAS) to prove, for the first time, that the reaction between LiBH4 and MgH2 can indeed occur during ball milling at room temperature. Through this BMAS process we have demonstrated unambiguously the formation of MgB2 and LiH during ball milling of MgH2 while aerosol spraying of the LiBH4/THF solution. In this BMAS process, aerosol spraying of the LiBH4/THF solution leads to the formation of LiBH4 nanoparticles which decompose to form Li2B12H12. The Li2B12H12 formed then reacts with MgH2 in situ during ball milling to form MgB2 and LiH. The discovery made in this study has significant implications in making LiBH4 + MgH2 as a viable system for reversible hydrogen storage applications near ambient temperature in the future. © 2015 Elsevier B.V.
Tsoi M.,Materials and Aerospace Engineering |
Chen R.-H.,Materials and Aerospace Engineering |
Tang Y.,Materials and Aerospace Engineering |
Gou J.,Materials and Aerospace Engineering
ASME International Mechanical Engineering Congress and Exposition, Proceedings | Year: 2010
Carbon nanofiber (CNF) papers, when incorporated onto the surface of glass fiber reinforced polyester composites, were known to enhance the fire-retarding capability by decreasing the peak heat release rate (PHRR) and slowing down the mass loss. In this experimental study, attempts were made to understand the thermal degradation mechanisms of the composites and nanocomposites. The temperature distribution within the composite substrate should be determined because the degradation rate is related to the temperature. The composite was prepared through vacuum-assisted resin transfer molding (VARTM) process. Samples of glass-polyester resin composites were investigated. Thermal conductivity data was calculated from embedded thermocouples on the composite for real-time temperature measurement. Mass loss data was collected using thermal gravimetric analysis on resin and CNF paper samples. These results should help to further understand the depth and degree of the degradation and provide an understanding of thermal properties in composites. Copyright © 2010 by ASME.