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Tsao, Bang-Hung
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Analysis and Control of Energy Storage in Aircraft Power Systems with Pulsed Power Loads

SAE International Journal of Aerospace

University of Dayton Research Institute-Luis C. Herrera, Bang-Hung Tsao
  • Journal Article
  • 2016-01-1981
Published 2016-09-20 by SAE International in United States
One of the main challenges in the power systems of future aircraft is the capability to support pulsed power loads. The high rise and fall times of these loads along with their high power and negative impedance effects will have an undesirable impact on the stability and dc bus voltage quality of the power system. For this reason, studying ways to mitigate these adverse effects are needed for the possible adoption of these type of loads. One of the technologies which can provide benefits to the stability and bus power quality is Energy Storage (ES). This ES is designed with the capability to supply high power at a fast rate.In this paper, the management of the ES to mitigate the effects of pulsed power loads in an aircraft power system is presented. First, the detailed nonlinear model of the power network with pulsed power loads is derived. Due to the large size of this model, a model order reduction is performed using a balanced truncation and a second order approximation. The three types of models…
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Sputtered Barium Titanate, Lead Zirconate Titanate, Barium Strontium Titanate Films for Capacitor Applications

U.S. Air Force, AFRL/PRPE, Wright-Patterson AFB-Sandra Fries Carr, Susan Heidger, Joseph A. Weimer
University of Dayton Research Institute-Bang-Hung Tsao
Published 2000-10-31 by SAE International in United States
Thin barium titanate(BT), lead zirconate titanate(PZT), barium strontium titanate(BST) films are being developed for use in microelectronics, electromechanical and optoelectronic applications. Thin BaTiO3, Pb(ZrTi)O3 and (BaSr)TiO3 film capacitor devices were fabricated using RF sputtering techniques. The typical dielectric constant of these film capacitors was in the range of 300 to 1140. These film capacitors had dissipation factors between 0.2% to 0.6 % before annealing and 4-6% after annealing. The film capacitors have breakdown voltages in the range of 1×105 V/cm to 1.2×106 V/cm. The resistivity was in the range of 1010 to 1012 ohm-cm before annealing and 1013 to 1014 ohm-cm after annealing. The capacitance of films produced to-date had little dependence on frequency. Thermal cycling in the temperature range of 50 to 300°C had very limited impact on the capacitance and dissipation factor. Measurements of dielectric and material properties are reported.
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Rolled Barium Titanate (Bt) Film Capacitor for Pulsed Power Application

K Systems Corporation-Bang-Hung Tsao
U.S. Air Force, AFRL/PRPE, Wright-Patterson AFB-Sandra Fries Carr, Joseph A. Weimer
Published 1999-08-02 by SAE International in United States
Thin barium titanate (BT) film is being developed for use in microelectronics, electromechanical and optoelectronic applications. For this study rolled thin BaTiO3 film capacitors were fabricated using RF sputtering techniques. Capacitor grade aluminum foil was used as the bottom electrode. The top electrode was sputtered aluminum film, which was used for quick measurement purposes. The as-deposited ceramic film on aluminum foil was very flexible at room temperature and could be easily rolled. The foil was masked to preserve side electrodes. The typical dissipation factors (DF) of these BT film capacitors were in the range of 0.002 to 0.005. A low dissipation factor is extremely important for pulsed power or high power filtering applications. These BT film capacitors had a parallel resistance of 15 to 20 mega-ohm. With the thickness of the film being 8,000 Å, the average dielectric constant was calculated to be 25. The insulation resistance was about 138 giga-ohm. The product of insulation resistance and leakage current (IR) is equal to 1014. The resistivity was calculated to be 8.1×1010 ohmcm. These film capacitors…
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Recrystallization Characteristics of Mo-W-Re-HfC Alloys for Thermionic Applications

UES, Inc.-Bang-Hung Tsao, Mysore L. Ramalingam
Wright Patterson AFB-Brian D. Donovan, Thomas R. Lamp
Published 1992-08-03 by SAE International in United States
Microstructural evolution of a Mo-10W-2Re-0.5HfC alloy was studied in the temperature range of 298 K to 2200 K. The typical characteristics of the microstructure were curly deformation bands, with nucleation at boundaries and subgrain coalescence. The recrystallization temperature of the Mo-10W-2Re-0.5HfC alloy was determined to be near 1950 K, which is comparable with 2125 K for W-4Re-0.35 HfC and 2000 K for W-0.35 HfC. Microhardness tests were performed before and after 1 hour of vacuum annealing and the results indicate that the mechanical strength of Mo-10W-2Re-0.5HfC is lower than that of W-4Re-0.35 HfC or W-0.35 HfC. X-ray diffraction and pole figures indicate that this particular alloy exhibits the primary texture (110) and secondary texture (112) which is normally observed in B.C.C. metals such as Molybdenum. The creep strengths of W-4Re-0.35HfC, TZM-Mo, and W-25Re-30Mo were evaluated and compared at the same stress level. The W-4Re-0.35HfC alloy was found to have the superior creep strength. The creep strength of the Mo-10W-2Re-0.5HfC alloy is comparable to that of TZM-Mo or W-25Re-30Mo making it a suitable alternative for thermionic…
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Orientational Effects on the Performance of a Heat Pipe Coupled Thermionic Converter

UES, Inc.-Mysore L. Ramalingam, Bang-Hung Tsao
Wright Lab.-Timothy J. Young
Published 1992-08-03 by SAE International in United States
The effects of collector heat pipe orientation upon the electrical and thermal performance of a planar thermionic converter were investigated. The high heat throughput of the converter must be carried away from the collector following electrical power production.The planar thermionic converter tested employs chemical-vapor-deposited rhenium on molybdenum electrodes, a separately heated two-phase cesium reservoir, and a radiantly coupled, electric emitter heater. The collector also functions as the evaporator end cap for the liquid sodium heat pipe. The converter fixture places the heat pipe in the reflux mode (evaporator below the condenser) and allows orientational changes of 15, 30, 45, and 60 degrees from the vertical.It was determined that the thermionic output performance is a relatively weak function of orientation angle in the range of 0 to 60°. As the emitter temperature increased, the effect of orientation on the converter performance increases. The trend is that maximum power and output voltage decreases as orientation increases.The performance of the heat pipe was also monitored at various emitter temperatures and orientations. The difference in the temperatures of the…
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