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A number of emerging military systems operate using short, repetitive, high-power pulses. Rotating electromechanical machines incorporating inertial storage are natural candidates for supplying these high power pulses. The short duty cycle characteristic of these devices introduces an interesting physics trade off in the choice of field excitation. A quantitative comparison of permanent magnet machines to copper coil systems is performed on an equal weigh basis. The results indicate that copper coil based systems using exciters are superior to permanent magnet counterparts in pulsed applications of 20 s and less. The recommended use of copper coils becomes stronger when the issues of magnet life due to vibration, thermal cycling, and slot harmonic heating are considered. ; Center for Electromechanics

Herein we report an easy approach for the preparation of graphene‐based materials suitable as electrodes for lithium‐ion capacitors (LICs). To the best of our knowledge, this is the first time that phosphorus‐functionalized graphene oxide (rGO800‐P) is used as negative (battery‐type) electrode in LICs technology. An activated carbon derived from the pyrolysis of graphene‐carbon composite served as positive (capacitor‐type) electrode. While phosphorus functionalization on the negative electrode enables fast Li + kinetics during insertion/extraction processes, the flat‐shaped morphology, large surface area and proper pore size distribution of the positive electrode enhance the double‐layer formation. Full LICs optimization, through oversizing the negative electrode, allows operating in the extended voltage window of 1.5‐4.5 V delivering high energy and power values (91 W h kg ‐1 AM at 145 W kg ‐1 AM and 33 W h kg ‐1 AM at 26,000 W kg ‐1 AM ) without compromising the cycling performance (76% capacitance retention after 10,000 cycles). ; The authors thank the European Union (Graphene Flagship, Core 3, Grant number 881603)

Technology and size constraints have limited the development of the end game mechanisms of today's modern military weapons. A smaller, more efficient means of powering these devices is needed, and explosive pulsed power devices could be that answer. While most prior research has been in the experimental field, there is a need for more theory-based research and a computer modeling capability. The objective of this research was to use experimental data collected by the US Army at Redstone Arsenal from their ferroelectric generator (FEG) design in combination with the ALEGRA-EMMA code to develop a computer model that can accurately represent an FEG and that can be verified against experimental data and used to predict future experiments. While the ALEGRA code is not capable of simulating the breakdown phenomenon seen in the open circuit cases, the model can accurately reproduce the peak values for the current but has problems reproducing the peak values for the voltage. Overall, the developed model provides a good baseline simulation capability that can be used as a springboard for future development with further research.

International audience ; Dealing with the energy management of a single converter hybrid power pack involving battery and super capacitor, the real condition simulation and the preliminary experimental results have been hereby given. Through of a suitable management of both super capacitors (Scaps) state of charge and the dc bus voltage, smoothed power demand is assigned to the battery pack, whereas high frequency power demand is managed by the Scaps pack. Because military vehicle application is the target of the related application, security-based constraints namely battery pack temperature, current and voltages thresholds, are taken into account. The developed energy management is applied through 16-bits Microchip microcontroller dsPIC33EP512MU810 by means of CAN and CANopen communication. The presented results need to be refined owing to the sampling time issues of the used CAN bus frames.

International audience ; Dealing with the energy management of a single converter hybrid power pack involving battery and super capacitor, the real condition simulation and the preliminary experimental results have been hereby given. Through of a suitable management of both super capacitors (Scaps) state of charge and the dc bus voltage, smoothed power demand is assigned to the battery pack, whereas high frequency power demand is managed by the Scaps pack. Because military vehicle application is the target of the related application, security-based constraints namely battery pack temperature, current and voltages thresholds, are taken into account. The developed energy management is applied through 16-bits Microchip microcontroller dsPIC33EP512MU810 by means of CAN and CANopen communication. The presented results need to be refined owing to the sampling time issues of the used CAN bus frames.

The Department of Defense (DoD) and commercial entities are dependent on chemical plating and coating processes to replace worn or eroded material on damaged parts. Air Force Logistics Centers have been forced to consider replacement methods for repair operations due to the tightening of government regulations on the use of toxic and hazardous materials. The electromagnetic coating process is a viable alternative to existing build-up methods, and is based on proven >railgun> technology. Railguns have been under development for 15 years by the DoD and are high energy capacity electrical systems designed for rapid acceleration of an object. Railguns are effective in accelerating projectiles to very high, armor piercing velocities exceeding 2 km/s. Current thermal spray technology limits coating velocities to the 1 km/s range. In the electromagnetic coating process, equipment similar to a railgun accelerates the coating material. The impressive acceleration capability of electromagnetic systems is expected to produce coatings with superior density and bond strength properties. In addition to potentially improving coating properties, the electromagnetic coating process may serve as a replacement for operations that generate hazardous chemical wastes, such as hard chrome plating. The purpose of the program is to identify, develop, and design a production system for high quality coatings in industrial manufacturing and repair operations. ; Center for Electromechanics

The effects of pulsed light (PL) treatments combined with a quality-stabilizing dip on the quality and antioxidant attributes of fresh-cut 'Golden delicious' apples was studied. Apple wedges were dipped into a solution of 1% w/v N-acetylcysteine and 0.5% w/v CaCl2 and flashed with broad-spectrum light with an overall radiant exposure of 4, 8,12 and 16 J.cm(-2). General microbial counts, colour, firmness, phenolic compounds and vitamin C contents were evaluated over 15 days at 5 degrees C. More pronounced reductions of the naturally-occurring microbiota were observed as the applied PL-dose increased. The quality-stabilizing pre-treatment effectively prevented browning phenomena on the cut-tissue surface. In addition, browning and oxidation were not promoted in PL flashed samples. Indeed, the initial contents in phenolic compounds and vitamin C were even better maintained than in untreated samples. Treatments of 8 and 16 J cm(-2) were most effective for maintaining the quality and antioxidant characteristics. Industrial relevance: Pulsed light technology is an emerging technique with good prospects for the decontamination of foods and food contact surfaces. Application of pulse light treatments for increasing safety and extending microbial shelf life of fresh-cut produce seems feasible. However, their effects on the quality and antioxidant characteristics of fruit need to be evaluated for successfully applying the technology at an industrial level. (C) 2015 Elsevier Ltd. All rights reserved. ; This work was supported by the Generalitat de Catalunya (2014 SGR 1000) and the Ministerio de Economía y Competitividad of the Spanish Government (AGL 2010-21572 and AGL2013-44851-R). O. Martín-Belloso thanks ICREA Academia Award. K. Avalos Llano thanks CONICET and Universidad Nacional del Nordeste (Argentina) for the postdoctoral grant and financial support.

Based on long term experience, collected mainly with military applications like Rail Guns and Active Armour, a range of optimized semiconductor devices for pulsed applications was developed by ABB Switzerland Ltd and described in this presentation. The presented devices are optimized for pulsed discharge and fit very well for switching the short but high electrical power demand used for magnetic forming. Devices are available in different versions with silicon wafer diameters up to 120 mm and blocking voltages of over 6500V. Because of the different application requirements a differentiation is made in device technology. Depending on the discharge circuit, devices for low, medium, or high di/dt can be selected and the difference in advantages and disadvantages between both technologies will be described. To minimize the inductance between switching device and freewheeling diode, ABB can integrate this diode monolithic on the switching wafer. These so called reverse conducting devices are very common for magnetic forming applications. Thyristor structures are commercially available up to 8500V with 120 mm silicon wafers and GTO-like structures are available up to 4500V with 91 mm silicon wafers. For higher voltages or higher currents a combination of devices in series and/or parallel connection is required. The presentation will also describe the evolution of complete discharge switching modules in the range of 10kV / 50 kJ, a large discharge system of 21kV / 200kA, and a newly designed high current switch in the range of 15kV / 3MJ. The solid state switch solutions offered today and those shown in the presentation are based on a standard platform of components existing already for several years. For reliability reasons it is of great importance that the switch assemblies for high current pulsed applications are designed in cooperation with the device manufacturer who has in-depth knowledge of the switching behavior of the semiconductor components under pulsed conditions. The advantage of a complete switch assembly is that the whole unit can be tested under application conditions. ABB has a test capability up to 65 kV and 85 kJ stored energy.

The present work aims to achieve pulsed laser deposition ofTiO2 nanostructures and investigate their nonlinear properties using z-scan technique.The second harmonic Q-switched Nd: YAG laser at repetition rate of 1Hz and wavelength of 532 nm with three different laser fluencies in the range of 0.77-1.1 J/cm2 was utilized to irradiate the TiO2 target. The products of laser-induced plasma were characterized by utilizing UV-Vis absorption spectroscopy, x-ray diffraction (XRD), atomic force Microscope (AFM),and Fourier transform infrared (FTIR). A reasonable agreement was found among the data obtained usingX-Ray diffraction, UV-Vis and Raman spectroscopy. The XRD results showed that the prepared TiO2 thin films were all crystallite structure with no impurity peaks of other elements. Also, their peak intensities were increased with increasing the ablating laser fluency. AFM measurements indicated that,during pulsed laser deposition, as the laser fluency was increased, the average diameter of the prepared TiO2 nanoparticles (TiO2 NPs)was decreased from 86 to 57 nm, althoughthe differences were increased with the increase in the laser fluency. The multiphoton absorption was investigated using ultra-fast femtosecond laser with the z-scan method.The impact of thickness of the prepared films on the non-linear absorption coefficient was studied as well.

373 378 5 4 ; S ; [EN] In this work we show the influence of the edge-effect on the electric field distribution and, hence, on the inner and outer capacitance in an inclined-plate capacitor system surrounded by an insulating medium taking into account the thickness of the conducting plates for a complete set of dimensions and insulating characteristics. Where available, we compare our results with previously published works. Finally, using statistical tools, we obtain approximate expression for computing the relationship between capacitance and insulation material characteristics, insulation gap, plate dimensions and angle. Bueno Barrachina, JM.; Cañas Peñuelas, CS.; Catalán Izquierdo, S. (2011). Capacitance Evaluation on Non-parallel Thick-Plate Capacitors by Means of Finite Element Analysis. Journal of Energy and Power Engineering. 5(4):373-378. doi:10.17265/1934-8975/2011.04.012