Sample records for sido buck converter

  1. Buck Converter Animation

    NSDL National Science Digital Library

    This website from the Thayer School of Engineering at Dartmouth College features an animation of a buck converter. A buck converter is a step-down DC to DC converter. Its design is similar to the step-up boost converter, and like the boost converter it is a switched-mode power supply that uses two switches (a transistor and a diode), an inductor and a capacitor.

  2. Discontinuous Buck Converter

    NSDL National Science Digital Library

    This animation, created by faculty at Dartmouth University, is a discontinuous buck converter. The resource features other animations such as boost and discontinuous converters. They also add simple diode, bridge and half-wave rectifiers. Although simple in design, this can still be a useful resource for those interested in electrical engineering.

  3. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

  4. Design of intrinsically safe buck DC\\/DC converters

    Microsoft Academic Search

    Shulin Liu; Jian Liu; Yinling Yang; Jiuming Zhong

    2005-01-01

    The maximum peak current of inductor of a buck DC-DC converter in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) are analyzed, respectively. It is pointed out that the maximum peak current through the inductor of a CCM buck converter occurs when both the input voltage and the output current reach the highest values. The inner-intrinsic safety of a

  5. Phase Current Unbalance Estimation in Multi-Phase Buck Converters

    E-print Network

    Sanders, Seth

    Phase Current Unbalance Estimation in Multi-Phase Buck Converters Gabriel Eirea and Seth R. Sanders- instantaneous values of the waveform, a frequency analysis ance in a multi-phase buck converter is presented with respect to one other are shown to is equivalent to a low-order matrix-vector multiplication or a be very

  6. Analysis and Applications of a Current-Sourced Buck Converter

    Microsoft Academic Search

    Wayne W. Weaver; Philip T. Krein

    2007-01-01

    In many power converter applications it is required that the topology have a current-sourced input. If a voltage step down is needed, then the choice of converter topologies is limited, or requires several stages. This paper presents a known, but rarely utilized, buck-type converter that has a current-sourced input. Analyses of the large-and small-signal models of the converter are presented

  7. Integrated, Low Voltage, DynamicallyIntegrated, Low Voltage, Dynamically Adaptive BuckAdaptive Buck--Boost ConverterBoost Converter

    E-print Network

    Rincon-Mora, Gabriel A.

    --Boost ConverterBoost Converter ­­ A TopA Top--Down Design ApproachDown Design Approach Analog Integrated Circuits voltage depending on work- load/throughput to extend battery life. Single inductor, non-inverting buck Improvement in battery life Low voltage Single cell operation (Li-ion/NiCd/NiMH/Fuel Cell) Integrated

  8. Optimizing the load transient response of the buck converter

    Microsoft Academic Search

    R. Redl; Brian P. Erisman; Zoltan Zansky

    1998-01-01

    The optimized gain of the voltage-error amplifier and current-mode control provide instantaneous transient response and small DC shift of the output voltage for step changes in the load current. This paper analyzes the system, determines the best compensation, provides design guidelines for buck converters powering Pentium(R) II processors and presents results of simulations and experiments

  9. Highly efficient PWM synchronous buck converter with optimized LDMOS

    NASA Astrophysics Data System (ADS)

    Roy, Swarnil; Mukherjee, Sagar; Sarkar, Chandan Kumar

    2015-07-01

    In this work, a design of high efficiency synchronous buck converter with an optimized LDMOS is presented which works in VHF frequency domain. The circuit performance of the buck converter is then analyzed and optimized to increase the efficiency and to reduce the power losses without modifying the circuit. The analysis and optimization is performed by varying the different device parameters like drift region doping concentration (DDrift) and drift region length (LDrift) along with the circuit level parameters like the dead time and the switching frequency. The effect of the parameters is found to reduce the power losses of the circuit. The circuit with optimized parameters yields 80% efficiency at 100 MHz switching frequency.

  10. Analysis of Discharge Spark Energy in Buck Converter of a Continuous Mode of Inductive Current

    Microsoft Academic Search

    Bao-chun GUI; Hong CHENG; Cong WANG; Huan-yu LU; Yun SHI

    2006-01-01

    The basic idea of intrinsically safe circuit and the discharge spark in the Buck converter in the explosive atmospheres were introduced. The Buck converter is the main topological structure of the switch type of intrinsically safe circuit, which has two working modes: continuous inductive current (CCM — continuous conduction mode) and discrete inductance current (DCM — discontinuous conduction mode). The

  11. Optimal design of inductance and capacitance of output intrinsically safe Buck DC-DC converters

    Microsoft Academic Search

    Shu-lin Liu; Yi-bo Ma; Yun-wu Zhang

    2010-01-01

    To obtain the optimal design method of the Inductance and Capacitance of output intrinsic safety Buck DCDC converter, the Output Short-Circuit Discharged Energy (OSCDE) of a buck DC-DC converter in Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM) are analyzed, respectively. It is pointed out that the energy in DCM is independent of inductance, while that in CCM increases

  12. Speed-sensorless tracking control of a DC-motor via a double Buck-converter

    E-print Network

    Knobloch,Jürgen

    the regulation of the angular velocity of the dc-motor shaft. A simple linear-time-varying state feedbackSpeed-sensorless tracking control of a DC-motor via a double Buck-converter J. Linares-Flores , J voltage of the first buck-converter and the angular velocity of the dc- motor shaft so that it tracks

  13. Two-Parameter Bifurcation Analysis of the Buck Converter

    NASA Astrophysics Data System (ADS)

    Colombo, Alessandro; Lamiani, Paola; Benadero, Luis; di Bernardo, Mario

    2009-01-01

    This paper is concerned with the analysis of two-parameter bifurcation phenomena in the buck power converter. It is shown that the complex dynamics of the converter can be unfolded by considering higher codimension bifurcation points in two-parameter space. Specifically, standard smooth bifurcations are shown to merge with discontinuity-induced bifurcation (DIB) curves, giving rise to intricate bifurcation scenarios. The analytical results are compared with those obtained numerically, showing excellent agreement between the analytical predictions and the numerical observations. The existence of these two-parameter bifurcation phenomena involving DIBs and smooth bifurcations, predicted in [P. Kowalczyk et al., Internat. J. Bifur. Chaos Appl. Sci. Engrg., 16 (2006), pp. 601-629; A. Colombo and F. Dercole, SIAM J. Appl. Dyn. Syst., submitted], is confirmed in this important class of systems.

  14. Single-inductor, multiple-output buck converter with parallel source transient recovery

    E-print Network

    King, Charles Jackson, III

    2009-01-01

    To address the need for multiple regulated voltage supplies in electronic devices, this thesis presents a modeling and design study of a single-inductor, multiple-output (SIMO) DC-DC buck converter with parallel source ...

  15. Magnetic Component based Analysis for Multiphase DC-DC Buck Converter

    Microsoft Academic Search

    H. N. Nagaraja; D. Kastha; A. Patra

    2006-01-01

    While meeting the future demand of microprocessor using multiphase synchronous buck converter, integrated magnetic components are used to reduce the size of the converter and improve efficiency. However, no analysis leading to simple equivalent circuit of the coupled system with arbitrary number of phases has been presented so far. This paper proposes a circuit based analysis method for such converters,

  16. Boost Converter With Coupled Inductors and Buck–Boost Type of Active Clamp

    Microsoft Academic Search

    Tsai-Fu Wu; Yu-Sheng Lai; Jin-Chyuan Hung; Yaow-Ming Chen

    2008-01-01

    This paper proposes a boost converter with coupled inductors and a buck-boost type of active clamp. In the converter, the active-clamp circuit is used to eliminate the voltage spike that is induced by the trapped energy in the leakage inductor of the coupled inductors. The active switch in the converter can still sustain a proper duty ratio even under high

  17. Snubbers in the Three-phase AC to DC Buck Converter

    Microsoft Academic Search

    Franc Mihalic; Dejan Kos; Miran Rodic; Miro Milanovic

    2006-01-01

    In this paper, investigation of effective snubber circuits in the three-phase AC to DC buck converter is presented. Based on the theoretical analysis and from the conventional matrix converters theory approach, the mathematical proof for an AC to DC power converter with unity input displacement factor (IDF) operation without current sensing, is provided. For the DC output current bulky inductance

  18. Analysis of Boundary Control for Buck Converters With Instantaneous Constant-Power Loads

    Microsoft Academic Search

    Chimaobi N. Onwuchekwa; Alexis Kwasinski

    2010-01-01

    This paper examines a boundary control for dc-dc buck converters subject to instantaneous constant-power loads. These loads introduce a destabilizing nonlinear effect on the converter through an inverse voltage term that leads to significant oscillations in the main bus voltage or its collapse. Converter dynamics are analyzed in both switching states and the various operating regions of switch interaction with

  19. A novel dual Boost\\/dual Buck AC\\/AC converter

    Microsoft Academic Search

    Chen Jiawei; Chen Jie; Gong Chunying

    2009-01-01

    A novel dual Boost\\/dual Buck AC-AC converter which is very suitable for the variable-frequency power system of airplane (360 Hz-800 Hz) is proposed in this paper. It is constructed by directly connection of a dual Boost rectifier and a dual Buck inverter which inherit the merits of high reliability and efficiency of them for no hidden danger of shoot-through and

  20. Commercial Buck Converters and Custom Coil Development for the ATLAS Inner Detector Upgrade

    SciTech Connect

    Dhawan, S.; Lanni, F.; Baker, O.; Chen, H.; Khanna, R.; Kierstead, J.; Lynn, D.; Musso, C.; Rescia, S.; Smith, H.; Tipton, P. and Weber, M.

    2010-04-01

    A new generation of higher gain commercial buck converters built using advanced short channel CMOS processes has the potential to operate in the Atlas Inner Detector at the Super Large Hadron Collider (sLHC). This approach would inherently be more efficient than the existing practice of locating the power conversion external to the detector. The converters must operate in a large magnetic field and be able to survive both high doses of ionizing radiation and large neutron fluences. The presence of a large magnetic field necessitates the use of an air core inductor which is developed and discussed here. Noise measurements will be made to investigate the effect of the high frequency switching of the buck converter on the sensitive front end electronics. Radiation hardness of selected buck converters and mosfets will also be reported.

  1. FLATNESS BASED CONTROL OF A BUCK-CONVERTER DRIVEN DC MOTOR

    E-print Network

    Knobloch,Jürgen

    carries a maximum armature current of 4 A. From the respective motor data the converter parameters noisy shape. This causes large forces acting on the motor me- chanics and also large currents whichFLATNESS BASED CONTROL OF A BUCK-CONVERTER DRIVEN DC MOTOR Felix Antritter ,1 Peter Maurer Johann

  2. A low noise high efficiency buck DC-DC converter with sigma---delta modulation

    Microsoft Academic Search

    Cai Shujiang; Pi Changming; Yan Wei; Li Wenhong

    2011-01-01

    Some research efforts to improve the efficiency and noise performance of buck DC---DC converters are explored. A carefully designed power MOSFET driver, including a dead time controller, discontinuous current mode (DCM) controller and gate width controller, is proposed to improve efficiency. Instead of PWM modulation, sigma-delta modulation is introduced into the feedback loop of the converter to move out the

  3. A buck converter operating in PFM mode, mathematical model and simulation analysis

    Microsoft Academic Search

    A. Morra; M. Piselli; M. Flaibani; A. Gola

    2007-01-01

    This paper describes a possible control method for the operation of a variable switching frequency buck converter. Starting from the ideal model for a Pulse Frequency Modulation (PFM) mode dc-dc converter [1], a simple control system, involving only two comparators and a latch is presented here. A mathematical model for this frequency modulated control system is developed and demonstrated. To

  4. Analysis and design of an active-clamp buck converter with coupled inductors

    Microsoft Academic Search

    T. F. Wu; J. C. Hung; Y. S. Lai; H. S. Nien; H. M. Su

    2005-01-01

    This paper presents analysis and design of an active-clamp buck converter with coupled inductors. The active switch in the converter can sustain a long enough duty cycle while it operates with a high step-down voltage ratio, reducing current stress significantly. In the converter, the active-clamp circuit is used to eliminate voltage spike induced from the leakage inductor of the coupled

  5. VSS approach to a full bridge buck converter used for AC sine voltage generation

    Microsoft Academic Search

    F. Boudjema; M. Boscardin; P. Bidan; J. C. Marpinard; M. Valentin; J. L. Abatut

    1989-01-01

    The authors present an application of variable structure systems (VSS) theory, and the associated sliding mode, to a full bridge buck converter used to produce an AC sine voltage. To design a sliding mode controller, the pole assignment method is used. The equivalent control method makes it possible to determine the existence of the sliding regime in the state space.

  6. Fully monolithic cellular buck converter design for 3-D power delivery

    E-print Network

    Sun, Jian

    A fully monolithic interleaved buck dc-dc point-of-load (PoL) converter has been designed and fabricated in a 0.18-mm SiGe BiCMOS process. Target application of the design is 3-D power delivery for future microprocessors, ...

  7. Stability analysis of a non-inverting synchronous buck-boost power converter for a solar power management system

    Microsoft Academic Search

    Jaw-Kuen Shiau; Chun-Jen Cheng; Ching-En Tseng

    2008-01-01

    This paper presents the stability analysis of a non-inverting synchronous buck-boost DC\\/DC power converter for a solar power management system. The system can operate in buck, buck-boost or boost mode according to the condition of the supply voltage. The variation of the supply voltage arises from the rapid changes of the atmospheric condition or sunlight incident angle. The stability margins

  8. Soft switching circuit for IGBTs in high-frequency buck converters using saturable inductors

    Microsoft Academic Search

    E. Dallago; M. Passoni; G. Venchi

    2004-01-01

    A PWM DC\\/DC buck converter with a soft-switching network using saturable inductors is presented. The circuit has soft-switching transition over a wide load range, with low electromagnetic emission and high efficiency. This paper presents its operating principle together with the relations for complete converter design. The design was applied to an IGBT prototype with a 300 V input voltage and

  9. Aggregated modeling and control of a boost-buck cascade converter for maximum power point tracking of a thermoelectric generator

    Microsoft Academic Search

    Rae-Young Kim; Jih-Sheng Lai

    2008-01-01

    For a wide output voltage ranged thermoelectric generator, it is necessary to have a DC-DC converter that allows voltage boost and buck functions. In this paper, a boost-buck cascade DC-DC converter is adopted to allow input voltage range from near 0 V to 25 V and output voltage range from 12.3 V to 16.5 V, needed for vehicle battery charging.

  10. Adaptive Control for Buck Power Converter Using Fixed Point Inducting Control and Zero Average Dynamics Strategies

    NASA Astrophysics Data System (ADS)

    Hoyos Velasco, Fredy Edimer; García, Nicolás Toro; Garcés Gómez, Yeison Alberto

    In this paper, the output voltage of a buck power converter is controlled by means of a quasi-sliding scheme. The Fixed Point Inducting Control (FPIC) technique is used for the control design, based on the Zero Average Dynamics (ZAD) strategy, including load estimation by means of the Least Mean Squares (LMS) method. The control scheme is tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The closed loop system shows adequate performance. The experimental and simulation results match. The main contribution of this paper is to introduce the load estimator by means of LMS, to make ZAD and FPIC control feasible in load variation conditions. In addition, comparison results for controlled buck converter with SMC, PID and ZAD-FPIC control techniques are shown.

  11. Three-level buck converter for envelope tracking in RF power amplifiers

    Microsoft Academic Search

    Vahid Yousefzadeh; Eduard Alarcon; Dragan MaksimoviC

    2005-01-01

    This paper proposes a three-level buck converter for efficient wide-bandwidth envelope tracking in RF power amplifiers (RFPA). The focus is on low-power battery-operated systems, and the goal is to enable practical implementation of the envelope elimination and restoration (EER) technique, which theoretically allows realization of a highly linear, highly efficient RFPA for non-constant envelope modulations. In terms of ripple, switching

  12. AC\\/AC Buck Converter Instantaneous Value Control Modeling, System Analyzing and Designing

    Microsoft Academic Search

    Ma Huasheng; Zhang Bo; Zheng Jianchao; Zhao Liang

    2005-01-01

    Close-loop control to the power electronics transformer (PET) was not well solved still now, we studied the basic topology of PET-AC\\/AC buck converter, built its small-signal model, analyzed its frequency characteristic, and pointed out that: under general inductive load condition, the open-loop model is an approximate second-order undamped oscillation system, it is marginally stable and output voltage oscillation can be

  13. Hysteresis-Current-Controlled Buck Converter Suitable for Li-Ion Battery Charger

    Microsoft Academic Search

    Fong-Cheng Yang; Chih-Chiang Chen; Jiann-Jong Chen; Yuh-Shyan Hwang; Wen-Ta Lee

    2006-01-01

    A new hysteresis-current-controlled (HCC) buck converter suitable for Li-ion battery charger is presented in this paper. The technique adopted in this charger is constant current\\/constant voltage dual mode, which is decided by the value of internal resistance of Li-ion battery. This technique will degrade the damage of Li-ion battery and improve the power efficiency of charger. The Li-ion battery charger

  14. A fixed-frequency pulsewidth modulation based quasi-sliding-mode controller for buck converters

    Microsoft Academic Search

    Siew-Chong Tan; Y. M. Lai; Chi K. Tse; Martin K. H. Cheung

    2005-01-01

    This paper presents the design and analysis of a fixed-frequency pulsewidth modulation (PWM)-based quasi-sliding-mode voltage controller for buck converters from a circuit design perspective. A practical design approach that aims at systematizing the procedure for the selection of the control parameters is presented. In addition, a simple analog form of the controller for practical realization is provided. The resulting controller

  15. Automotive DC-DC bidirectional converter made with many interleaved buck stages

    Microsoft Academic Search

    Oscar García; Pablo Zumel; A. de Castro; A. Cobos

    2006-01-01

    Interleaving technique is used in some applications due to its advantages regarding filter reduction, dynamic response, and power management. In dual battery system vehicles, the bidirectional dc-dc converter takes advantage of this technique using three-to-five paralleled buck stages. In this paper, we propose the use of a much higher number of phases in parallel together with digital control. It will

  16. Digital PWM\\/PFM controller with input voltage feed-forward for synchronous buck converters

    Microsoft Academic Search

    Xu Zhang; Dragan Maksimovic

    2008-01-01

    This paper describes a digital pulse-width modulation\\/pulse-frequency modulation (PWM\\/PFM) controller with input voltage feed-forward for synchronous buck DC-DC converters. The controller includes automatic PWM\\/PFM mode switching and effective synchronous operation with a minimum number of active components and without the need for current sensing in PFM mode of operation. Input-voltage feed-forward improves efficiency and dynamic performance over a wide range

  17. EMI analysis methods for synchronous buck converter EMI root cause analysis

    Microsoft Academic Search

    Keong W. Kam; David Pommerenke; Cheung-Wei Lam; Robert Steinfeld

    2008-01-01

    DC\\/DC synchronous buck converters cause broadband emissions. A variety of methods are applied to analyze the root cause of the EMI. Time-domain voltage measurement and joint-time-frequency analysis allows to determine the location of the noise source. The near field scan reveals the current paths, and impedance measurement and 3D modeling can be used for further analysis of the noise source.

  18. A 3-phase buck-boost converter for lowering the input current distortion of a voltage source inverter drive

    SciTech Connect

    Salmon, J.C.; Olsen, S. [Univ. of Alberta, Edmonton (Canada). Dept. of Electrical Engineering; Nowicki, E. [Univ. of Calgary, Alberta (Canada). Dept. of Electrical and Computing Engineering

    1995-12-31

    This paper presents a 3-phase buck-boost switchmode converter that lowers the input harmonics drawn by a voltage source pwm inverter drive. The buck-boost converter examined, rated with a 0.26 per-unit current and drawing 6% of the total drive input power, is connected in parallel with the drive`s main diode bridge and LC filter, 94% of the drive power is drawn through the diode rectifier. The low electrical stresses associated with the buck-boost converter, in addition to the small number of high frequency switching components, makes the drive topology robust, conducive to soft-switching techniques and lowers the generation of emi-rfi. The rectifier topologies are suitable for regulating the dc voltage rails for 2-level and 3-level inverters. For 3-level inverter drives using a center-tapped capacitor dc-rail, the proposed rectifiers can compensate for load imbalances and maintain equal voltage drops across the two dc-rails. Since the buck-boost switchmode converter is separate from the main drive diode rectifier, the drive can continue to operate satisfactorily even if the buck-boost converter fails. This same feature makes the buck-boost converter unit suitable as a drive option or for retrofitting. The drive configurations examined in the paper are verified with experimental results and Spice simulations.

  19. A novel buck/LDO dual-mode DC—DC converter for efficiency improvement

    NASA Astrophysics Data System (ADS)

    Shiquan, Fan; Zhongming, Xue; Hao, Lu; Hui, Zhao; Li, Geng

    2013-10-01

    A novel buck/LDO dual-mode (BLDM) converter using a multiplexing power MOS transistor is proposed, which adaptively switches between buck mode and LDO mode to improve conversion efficiency. The chip was fabricated in a standard 0.35 ?m CMOS process. Measurement results show that the peak efficiency is 97%. For the light load operation, the efficiency is improved by 14%. The efficiency keeps higher than 82.5% for the load current of 50 mA without any complex control or extra EMI due to the normal method of pulse frequency modulation (PFM) control used for improving the light load efficiency. It does not cost much extra chip area because no additional regulator PMOS is needed. It is more suitable for noise-restricted systems and battery-powered electronic devices for when battery voltage drops because of long hours of work.

  20. Generalized analysis of integrated magnetic component based low voltage interleaved DC-DC buck converter for efficiency improvement

    Microsoft Academic Search

    H. N. Nagaraja; Amit Patra; Debaprasad Kastha

    2005-01-01

    The multi channel interleaving buck converter with small inductance has proved to be suitable for voltage regulator modules requiring low output voltages, high output currents and fast transient response. Integrated magnetic components are used to reduce the size of the converter and improve efficiency. However, no analysis leading to a simple equivalent circuit of the coupled system with arbitrary number

  1. A three-level buck converter to regulate a high-voltage DC-to-AC inverter

    E-print Network

    Schrock, Kenneth C

    2008-01-01

    A three-level buck converter is designed and analyzed, and shown to be suitable as a high-voltage down converter as a pre-regulation stage for a 600 watt DC-to-AC power inverter. Topology selection for the inverter is ...

  2. Sensorless Load Torque Estimation and Passivity Based Control of Buck Converter Fed DC Motor

    PubMed Central

    Kumar, S. Ganesh; Thilagar, S. Hosimin

    2015-01-01

    Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper. PMID:25893208

  3. Equivalent-resistance based on the analysis of inductor-disconnected discharge behavior for intrinsic safety Buck converters

    Microsoft Academic Search

    Shu-lin Liu; Jian Liu; Yan Li; Hong Mao

    2008-01-01

    An Equivalent-Resistance based Analysis Method (ERAM) was proposed, which can convert the Inductor-Disconnected Discharge\\u000a (IDD) behavior of the Intrinsically Safe Buck Converter (ISBC) into that of an Equivalent Simple-Inductive-Circuit (ESIC).\\u000a According to the inductor disconnected equivalent circuit corresponding to the most dangerous operating case of the converter,\\u000a the arc discharge time and the variation of output-voltage during the IDD were

  4. Low-temperature operation of a Buck DC/DC converter

    NASA Technical Reports Server (NTRS)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    Low-temperature (77 K) operation of a 42/28 V, 175 W, 50 kHz PWM Buck DC/DC converter designed with commercially available components is reported. Overall, the converter losses decreased at 77 K compared to room temperature operation. A full-load efficiency of 97 percent was recorded at liquid-nitrogen temperature, compared to 95.8 percent at room temperature. Power MOSFET operation improved significantly where as the output rectifier operation deteriorated at low-temperature. The performance of the output filter inductor and capacitor did not change significantly at 77 K compared to room temperature performance. It is possible to achieve high-density and high efficiency power conversion at low-temperatures due to improved electronic, electrical and thermal properties of materials.

  5. A buck converter with simple maximum power point tracking for power electronics education on solar energy systems

    Microsoft Academic Search

    Dylan D. C. Lu; R. H. Chu; S. Sathiakumar; V. G. Agelidis

    2007-01-01

    This paper introduces a solar photovoltaic (PV) system suitable for undergraduate engineering education and training. The system consists of a buck converter using a simple maximum power point tracking (MPPT) method. Constant voltage control method is used for the approximate tracking and is implemented by analogue circuits. The circuit simplicity helps students to appreciate the benefit of MPPT in a

  6. An Optimal Current Observer for Predictive Current Controlled Buck DC-DC Converters

    PubMed Central

    Min, Run; Chen, Chen; Zhang, Xiaodong; Zou, Xuecheng; Tong, Qiaoling; Zhang, Qiao

    2014-01-01

    In digital current mode controlled DC-DC converters, conventional current sensors might not provide isolation at a minimized price, power loss and size. Therefore, a current observer which can be realized based on the digital circuit itself, is a possible substitute. However, the observed current may diverge due to the parasitic resistors and the forward conduction voltage of the diode. Moreover, the divergence of the observed current will cause steady state errors in the output voltage. In this paper, an optimal current observer is proposed. It achieves the highest observation accuracy by compensating for all the known parasitic parameters. By employing the optimal current observer-based predictive current controller, a buck converter is implemented. The converter has a convergently and accurately observed inductor current, and shows preferable transient response than the conventional voltage mode controlled converter. Besides, costs, power loss and size are minimized since the strategy requires no additional hardware for current sensing. The effectiveness of the proposed optimal current observer is demonstrated experimentally. PMID:24854061

  7. Sampled-Data and Harmonic Balance Analyses of Average Current-Mode Controlled Buck Converter

    E-print Network

    Chung-Chieh Fang

    2012-02-21

    Dynamics and stability of average current-mode control of buck converters are analyzed by sampled-data and harmonic balance analyses. An exact sampled-data model is derived. A new continuous-time model "lifted" from the sampled-data model is also derived, and has frequency response matched with experimental data reported previously. Orbital stability is studied and it is found unrelated to the ripple size of the current-loop compensator output. An unstable window of the current-loop compensator pole is found by simulations, and it can be accurately predicted by sampled-data and harmonic balance analyses. A new S plot accurately predicting the subharmonic oscillation is proposed. The S plot assists pole assignment and shows the required ramp slope to avoid instability.

  8. A High-Power Input-Parallel Output-Series Buck and Half-Bridge Converter and Control Methods

    Microsoft Academic Search

    Qing Du; Bojin Qi; Tao Wang; Tao Zhang; Xiao Li

    2012-01-01

    The two-switch cascade converter is the most appropriate solution for efficient high-power applications among the existing converter topologies. However, the cascade structure and the nonlinear dc gain of boost circuit are more likely to cause severe oscillations if the criterion for the selection of the operation mode is chosen improperly during step-up\\/step-down transition. A novel high-power input-parallel output-series buck-half-bridge (IPOSBHB)

  9. Adaptive terminal sliding-mode control strategy for DC-DC buck converters.

    PubMed

    Komurcugil, Hasan

    2012-11-01

    This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DC buck converters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to assure finite time convergence of the output voltage error to the equilibrium point and integrate an adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In addition, the influence of the controller parameters on the performance of closed-loop system is investigated. It is observed that the start up response of the output voltage becomes faster with increasing value of the fractional power used in the sliding function. On the other hand, the transient response of the output voltage, caused by the step change in the load, becomes faster with decreasing the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a compromise between start up and transient responses of the converter. Performance of the proposed ATSMC strategy has been tested through computer simulations and experiments. The simulation results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies. It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes. PMID:22877744

  10. Challenge on compact size DC-DC buck converters with high-speed current sensor and on-chip inductors

    Microsoft Academic Search

    Shih-Min Chen; Chun-Yu Hsieh; Ke-Horng Chen

    2007-01-01

    This paper proposes a compact size DC-DC buck converter toward on-chip inductors and minimized external components. Multi-phase, high switching frequency and pseudo continuous conduction mode (PCCM) techniques achieve the possibility to implement on-chip inductors. The effective inductance is about 20nH. Due to high switching frequency above 20MHz, it is a challenge to have a highly accurate current sense for high

  11. A novel soft-switched, high-frequency, high-efficiency, high-current 12 V voltage regulator-the phase-shift buck converter

    Microsoft Academic Search

    Jia Wei; Fred C. Lee

    2003-01-01

    This paper presents two novel soft-switched high-frequency high-efficiency, fast transient response 12 V voltage regulator (VR) topologies-the phase-shift buck (PSB) and the matrix-transformer phase-shift buck (MTPSB)-for high current applications. They improve efficiency at high switching frequencies and also feature very simple magnetic structures. For future high-frequency, high-current 12 V VRs, PSB and MTPSB converters are the cost-effective solutions. Experimental results

  12. SEMICONDUCTOR INTEGRATED CIRCUITS: DCM, FSM, dead time and width controllers for a high frequency high efficiency buck DC-DC converter over a wide load range

    Microsoft Academic Search

    Pi Changming; Yan Wei; Zhang Ke; Li Wenhong

    2010-01-01

    This paper presents a width controller, a dead time controller, a discontinuous current mode (DCM) controller and a frequency skipping modulation (FSM) controller for a high frequency high efficiency buck DC-DC converter. To improve the efficiency over a wide load range, especially at high switching frequency, the dead time controller and width controller are applied to enhance the high load

  13. IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 11, NOVEMBER 2013 4885 An Improved Soft-Switching Buck Converter With Coupled Inductor

    E-print Network

    Mi, Chunting "Chris"

    Soft-Switching Buck Converter With Coupled Inductor Lei Jiang, Chunting Chris Mi, Siqi Li, Chengliang with soft-switching capability, which operates under a zero-current-switching condition at turn on and a zero-voltage- switching condition at turn off. In order to realize soft switching, based on a basic

  14. Single-inductor dual-input dual-output buck-boost fuel-cell-li-ion charging DC-DC converter supply

    Microsoft Academic Search

    Suhwan Kim; G. A. Rincon-Mora

    2009-01-01

    Buck or boost single-inductor dual-input dual-output (SIDIDO) converters are popular in power-management and energy-harvesting applications. The fuel cell-Li-ion hybrid, unlike most applications discussed in literature, draws energy and power from a 0.6 V fuel cell and a 2.7-to-4.2 V Li-ion battery to supply a 1 V load and recharge the Li-ion battery, when unloaded, requiring a buck-boost charger-supply circuit. To

  15. Adaptive switching frequency buck DC—DC converter with high-accuracy on-chip current sensor

    NASA Astrophysics Data System (ADS)

    Jinguang, Jiang; Fei, Huang; Zhihui, Xiong

    2015-05-01

    A current-mode PWM buck DC—DC converter is proposed. With the high-accuracy on-chip current sensor, the switching frequency can be selected automatically according to load requirements. This method improves efficiency and obtains an excellent transient response. The high accuracy of the current sensor is achieved by a simple switch technique without an amplifier. This has the direct benefit of reducing power dissipation and die size. Additionally, a novel soft-start circuit is presented to avoid the inrush current at the starting up state. Finally, this DC—DC converter is fabricated with the 0.5 ?m standard CMOS process. The chip occupies 3.38 mm2. The accuracy of the proposed current sensor can achieve 99.5% @ 200 mA. Experimental results show that the peak efficiency is 91.8%. The input voltage ranges from 5 to 18 V, while a 2 A load current can be obtained. Project supported by the National Natural Science Foundation of China (No. 41274047), the Natural Science Foundation of Jiangsu Province (No. BK2012639), the Science and Technology Enterprises in Jiangsu Province Technology Innovation Fund (No. BC2012121), and the Changzhou Science and Technology Support (Industrial) Project (No. CE20120074).

  16. Integrated Magnetic Component based Analysis for Interleaved DC-DC Buck Converter

    Microsoft Academic Search

    H. N. Nagaraja; A. Patra; D. Kastha

    2005-01-01

    Integrated magnetic components are used to reduce the size of the converter and improve efficiency. However, no analysis leading to simple equivalent circuit of the coupled system with arbitrary number of phases has been presented so far. This paper proposes a circuit based analysis method for such converters, which leads to precise performance prediction and design equations. It is shown

  17. Chaos control in DC arc furnaces powered by parallel DC-DC buck converters

    Microsoft Academic Search

    Gherman Lucian; Rusu Anghel Stela; Topor Marcel; Sergiu Mezinescu

    2011-01-01

    We study the effects of chaos based control of the DC arc furnace operation. The chaos models for DC arc furnace have been proposed in several papers(1,2,3), but until now there is no reference to a control strategy concerning chaotic voltage variation in DC arc furnace operation. There is some practical application of chaos suppression for DC-DC converters. However the

  18. Achieving Maximum Power from Thermoelectric Generators with Maximum-Power-Point-Tracking Circuits Composed of a Boost-Cascaded-with-Buck Converter

    NASA Astrophysics Data System (ADS)

    Park, Hyunbin; Sim, Minseob; Kim, Shiho

    2015-06-01

    We propose a way of achieving maximum power and power-transfer efficiency from thermoelectric generators by optimized selection of maximum-power-point-tracking (MPPT) circuits composed of a boost-cascaded-with-buck converter. We investigated the effect of switch resistance on the MPPT performance of thermoelectric generators. The on-resistances of the switches affect the decrease in the conversion gain and reduce the maximum output power obtainable. Although the incremental values of the switch resistances are small, the resulting difference in the maximum duty ratio between the input and output powers is significant. For an MPPT controller composed of a boost converter with a practical nonideal switch, we need to monitor the output power instead of the input power to track the maximum power point of the thermoelectric generator. We provide a design strategy for MPPT controllers by considering the compromise in which a decrease in switch resistance causes an increase in the parasitic capacitance of the switch.

  19. Development of Buck-Type Single-Phase to Three-Phase Power Converter with Active Buffer

    NASA Astrophysics Data System (ADS)

    Ohnuma, Yoshiya; Itoh, Jun-Ichi

    This paper proposes a novel single-phase to three-phase power converter that can reduce the capacitance value of the smoothing capacitor in the DC link part. In the case of the single-phase converter, a large smoothing capacitor is required to absorb a power ripple with a frequency twice that of the power supply. The proposed method involves the use of an indirect matrix converter with an active snubber to absorb the power ripple. Therefore, the proposed system does not require a reactor and large energy buffer, such as a smoothing capacitor. Moreover, a diode bridge can be used on the rectifier stage in the proposed circuit. In this paper, the basic operation and validity of the proposed method are confirmed by simulation and experiment result. Thus, it is confirmed that good waveforms for input and output currents can be obtained by the proposed method.

  20. Design and construction of a four-channel interleaved buck dc\\/dc converter for an electric boat application

    Microsoft Academic Search

    N. Bairachtaris; V. Petroulas; A. Safacas; E. Tatakis; S. Tsotoulidis

    2010-01-01

    This paper focuses on the design and construction of an electric drive system for an electric boat. A number of technical interventions were made to convert a simple boat to an electrically driven boat. In our days the electric boats and the electric propulsion in general constitute a part of the electric transportation. The electric transportation seems to be an

  1. Power converters and amplifiers (review of \\

    Microsoft Academic Search

    Marian Kazmierkowski

    2009-01-01

    This book is a comprehensive textbook in the areas of electrical, electronics, and telecommunications engineering. It consists of 17 chapters and two appendices. Some of the topics covered include: buck PWM DC-DC converters; boost PWM DC-DC converters; buck-boost-PWM DC-DC converters; half-bridge and full-bridge converters; push-pull PWM DC-DC converters; open-loop small-signal characteristics of boost converters for CCM; current-mode control of boost

  2. A new soft-switched resonant buck-type rectifier with constant switching frequency

    Microsoft Academic Search

    Jagjitpati Shukla; B. G. Fernandes

    2003-01-01

    A new three-phase soft-switched AC-to-DC buck converter operating at constant switching frequency and drawing current at unity power-factor from the source is proposed. Unlike other three-phase resonant switch buck-type rectifiers reported in the literature, the switching frequency of this converter is held constant. The proposed converter uses two switches, which are soft-switched. This results in reduced switching losses and electromagnetic

  3. Boost Converter Animation

    NSDL National Science Digital Library

    This animation, created by faculty at Dartmouth University, is a boost converter. The resource features other animations such as buck and discontinuous converters. They also add simple diode, bridge and half-wave rectifiers. Although simple in design, this can still be a useful resource for those interested in electrical engineering.

  4. Single Inductor Dual Output Buck Converter 

    E-print Network

    Eachempatti, Haritha

    2010-07-14

    of value 3V. The main focus areas are low cross regulation between the outputs and supply of completely independent load current levels while maintaining desired values (1.2V,1.5V) within well controlled ripple levels. Dynamic hysteresis control is used...

  5. A New Bidirectional Three-phase Interleaved Isolated Converter with Active Clamp

    Microsoft Academic Search

    Hanju Cha; Jungwan Choi; Woojung Kim; Vladimir Blasko

    2009-01-01

    In this paper, a new bidirectional three-phase dc-dc converter and three-phase PWM strategies have been proposed for battery application. The proposed converter acts as an three-phase isolated buck converter when battery is charged from dc link (buck mode) and an three-phase isolated boost converter when battery discharges energy (boost mode). In the buck mode, three-phase hybridge rectifier is employed to

  6. Wilbur "Buck" Clayton Collection

    NSDL National Science Digital Library

    For over fifty years, Wilbur "Buck" Clayton brought his special brand of trumpet magic to audiences around the world. Born in Parsons, Kansas, Clayton was a prominent member of Count Basie's orchestra and he went on tour for the State Department as well. This digital collection from the Miller Nichols Library at the University of Missouri-Kansas City presents over 1500 photographs from this collection documenting Clayton's life and career. Visitors can browse the collection, and there are some great photos of Clayton as a small child and of course, some excellent photos of him collaborating with other jazz legends like Pee Wee Russell, Joe Turner, and Buddy Tate. Visitors with an interest in specific images can use the search feature to look for items using each photograph's details.

  7. Analysis of Piecewise Constant Models of Current Mode Controlled DC-DC Converters

    Microsoft Academic Search

    Takahiro Kabe; Sukanya Parui; Hiroyuki Torikai; Soumitro Banerjee; Toshimichi Saito

    2007-01-01

    SUMMARY Buck, boost, and buck-boost converters constitute large class of dc-dc converters used in practice and are interesting nonlinear dy- namical systems. It has been shown earlier that various nonlinear phenom- ena including subharmonics and chaos can be observed in these converters. In this paper we show that with the simplifying assumption that voltage regulation is achieved in high frequency

  8. Modelling, analyses and design of switching converters

    NASA Technical Reports Server (NTRS)

    Cuk, S. M.; Middlebrook, R. D.

    1978-01-01

    A state-space averaging method for modelling switching dc-to-dc converters for both continuous and discontinuous conduction mode is developed. In each case the starting point is the unified state-space representation, and the end result is a complete linear circuit model, for each conduction mode, which correctly represents all essential features, namely, the input, output, and transfer properties (static dc as well as dynamic ac small-signal). While the method is generally applicable to any switching converter, it is extensively illustrated for the three common power stages (buck, boost, and buck-boost). The results for these converters are then easily tabulated owing to the fixed equivalent circuit topology of their canonical circuit model. The insights that emerge from the general state-space modelling approach lead to the design of new converter topologies through the study of generic properties of the cascade connection of basic buck and boost converters.

  9. Conference James F.Buckli

    ScienceCinema

    None

    2011-04-25

    L'association du personnel a le plaisir d'accueillir Mons. James F.Buckli, astronaute, né en 1947. Il a participé à la mission Space Lab D1 qui pour la première fois mettait 8 personnes sur orbite.L'ass.du pers. remercie aussi Gordon White(s) de la mission américaine d'avoir permis d'organiser cette conférence

  10. Design of a synchronous-rectified buck bootstrap MOSFET driver for voltage regulator module

    Microsoft Academic Search

    Ming Kong; Wei Yan; Wenhong Li

    2007-01-01

    A high voltage driver optimized for driving two N-channel power MOSFETs, which are the two switches in a non-isolated synchronous buck power converter, is presented. Adaptive overlap protection circuit is incorporated to prevent both upper and lower MOSFETs from conducting simultaneously. The high side driver can be bootstrapped and is designed to handle high voltage slew rate. Simulation results demonstrate

  11. Application of EXCEL for analyzing DC\\/DC converters

    Microsoft Academic Search

    Peter H. WURM; Felix A. HIMMELSTOSS

    1998-01-01

    EXCEL is an often used and easily accessible calculation and drawing tool. The application for analyzing converters is therefore obvious. A special step-down converter is used to explain and to show the efficiency and usefulness of this tool for technical applications. The use of tapped inductors in the classical buck converter leads to high step-down ratios overcoming the extreme duty

  12. A Digital PWM Regulator Based on Serial-Error Correcting Mechanism for DC-DC Buck Conversion

    Microsoft Academic Search

    P. J. W. HuangandS; S. H. L. Tu

    2005-01-01

    This paper describes the design and implementation of a digital pulse-width modulation (PWM) regulator using a serial feedback error voltage to adjust the input voltage of a high frequency switching dc-dc buck converter. The digital controller comprises an error process unit (EPU), a PID compensator and a digital PWM. The employment of a serial comparator and an error process unit

  13. Internet based toolkit for simulation of DC\\/DC converters

    Microsoft Academic Search

    Sevki Demirbas; Gulrkan Mutlu

    2011-01-01

    Ab stract- In this study, a simulation toolkit for buck, boost and buck-boost DC\\/DC converters has been implemented. By using developed software, users can be connected to the system from any computer having internet connection and can be perform the experiments. The simulation toolkit has been realized with Matlab&Simulink and LabVIEW software. Matlab&Simulink has been used for simulation of the

  14. A novel digital PWM controller with dual-regulating mechanism for DC-DC buck conversion

    Microsoft Academic Search

    Steve Hung-Lung Tu; Sheng-Kai Chuang; Sheng-Fa Hsiao

    2008-01-01

    A novel dual-regulating mechanism for dc-dc buck conversion, which employs an inverter array based analog-to-digital (A\\/D) converter and the system feedback error signal to perform a fine regulation of the output voltage is presented. Based on this regulating mechanism, the proposed controller makes the output voltage converge efficiently. The proposed digital controller comprises a dual-regulating mechanism based error process unit

  15. 23. Photocopy of photograph (from the Bucks County Historical Society) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. Photocopy of photograph (from the Bucks County Historical Society) photographer and date unknown VIEW FROM THE SOUTHWEST - Fonthill, East Court Street, State Route 313 vicinity, Doylestown, Bucks County, PA

  16. 20. Photocopy of photograph (from the Bucks County Historical Society) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. Photocopy of photograph (from the Bucks County Historical Society) photographer and date unknown GENERAL VIEW FROM THE SOUTHWEST - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  17. Application handbook for a Standardized Control Module (SCM) for DC-DC converters, volume 1

    NASA Technical Reports Server (NTRS)

    Lee, F. C.; Mahmoud, M. F.; Yu, Y.

    1980-01-01

    The standardized control module (SCM) was developed for application in the buck, boost and buck/boost DC-DC converters. The SCM used multiple feedback loops to provide improved input line and output load regulation, stable feedback control system, good dynamic transient response and adaptive compensation of the control loop for changes in open loop gain and output filter time constraints. The necessary modeling and analysis tools to aid the design engineer in the application of the SCM to DC-DC Converters were developed. The SCM functional block diagram and the different analysis techniques were examined. The average time domain analysis technique was chosen as the basic analytical tool. The power stage transfer functions were developed for the buck, boost and buck/boost converters. The analog signal and digital signal processor transfer functions were developed for the three DC-DC Converter types using the constant on time, constant off time and constant frequency control laws.

  18. DC-DC Converters with a Novel Hysteretic PWM Controller

    Microsoft Academic Search

    Terukazu Sato; Takashi Nabeshima; Kimihiro Nishijima; Tadao Nakano

    2006-01-01

    DC-DC converters with a novel hysteretic PWM controller are presented. A novel feedback network is proposed which behaves as a PID controller. Fast transient response and no steady state error of the output voltage are achieved. Steady state and dynamic analysis are performed and confirmed by experimental results for a 5 V to 1.5 V prototype buck converter. As a

  19. Effects of increasing switching frequency in frequency modulated power converters

    Microsoft Academic Search

    Janis Jankovskis; Deniss Stepins; Dmitrijs Pikulins

    2010-01-01

    The paper considers the effect of increasing switching frequency on a frequency modulated (FM) buck converter parameters: efficiency, output voltage ripples and electromagnetic interference (EMI) attenuations. The converter operating in continuous and discontinuous conduction modes (CCM and DCM respectively) is analyzed analytically, by simulations in Simulink and experimentally. The results obtained show that increasing switching frequency can significantly reduce the

  20. Performance evaluations on soft-switching boost power converter with a single auxiliary passive resonant snubber

    Microsoft Academic Search

    M. Nakamura; M. Shimada; T. Myoui; H. Sadakata; S. Moisseev; M. Nakaoka

    2001-01-01

    This paper presents boost and buck and buck-boost circuit topologies of high-frequency soft switching transition PWM chopper type DC-DC high power converters with a single auxiliary passive resonant snubber. In the proposed boost power converter circuits operating under the principle of ZCS turn-on and ZVS turn-off commutation schemes, the capacitor and inductor in the auxiliary passive resonant circuit works as

  1. Buck CreekWatershed Protection Plan

    E-print Network

    State Soil and Water Conservation Board (Project 06-11) U.S. Environmental Protection Agency Developed the Texas State Soil and Water Conservation Board and U.S. Environmental Protection Agency. Buck Creek include: · Texas State Soil and Water Conservation Board · USDA-APHIS Wildlife Services · USDA Farm

  2. Breeding Soundness Examinations of Rams and Bucks

    E-print Network

    Breeding Soundness Examinations of Rams and Bucks Lynn Pezzanite, Animal Sciences Student, Purdue the ability to settle a large portion of females early in the breeding season and sire offspring of settling females, producers can perform breeding soundness examinations (BSEs). Up to 10 to 15 percent

  3. DC-DC converter design for battery-operated systems

    Microsoft Academic Search

    B. Arbetter; R. Erickson; D. Maksimovic

    1995-01-01

    This paper describes performance, design and optimization of DC-DC converters for energy limited, battery operated systems. Variable-frequency operation is used to achieve voltage regulation and high efficiency for an extremely wide range of load currents. An experimental 15 W, 3.3 V buck converter has been constructed to demonstrate design and optimization techniques. The converter employs synchronous rectification to reduce conduction

  4. A new power converter for ISA 42 V powernet system using matrix converter theory and Z-source inverter concepts

    Microsoft Academic Search

    Keping You; M. F. Rahman

    2005-01-01

    This paper proposes a new converter for the 42 V ISA system. The problem of the low voltage rating of the AC machine developing regulated 42 V with input power factor correction has bee addressed in this paper. The proposed converter uses a matrix converter coupled with a Z-source inverter which achieves boost mode operation DC-AC conversion and buck AC-DC

  5. Artificial Neural Identification and LMI Transformation for Model Reduction-Based Control of the Buck Switch-Mode Regulator

    NASA Astrophysics Data System (ADS)

    Al-Rabadi, Anas N.

    2009-10-01

    This research introduces a new method of intelligent control for the control of the Buck converter using newly developed small signal model of the pulse width modulation (PWM) switch. The new method uses supervised neural network to estimate certain parameters of the transformed system matrix [Ã]. Then, a numerical algorithm used in robust control called linear matrix inequality (LMI) optimization technique is used to determine the permutation matrix [P] so that a complete system transformation {[B˜], [C˜], [?]} is possible. The transformed model is then reduced using the method of singular perturbation, and state feedback control is applied to enhance system performance. The experimental results show that the new control methodology simplifies the model in the Buck converter and thus uses a simpler controller that produces the desired system response for performance enhancement.

  6. Hydrologic data for northern Bucks County, Pennsylvania

    USGS Publications Warehouse

    Schreffler, Curtis L.; McManus, B.C.; Rowland-Lesitsky, C. J.; Sloto, R.A.

    1994-01-01

    Hydrologic and water-quality data were collected in northern Bucks County, Pa., as part of a study conducted by the U.S. Geological Survey, in cooperation with Bridgeton, Buckingham, Nockamixon, Plumstead, Solebury, Springfield, Tinicum, and Wrightstown Townships and New Hope Borough. Hydrologic data on ground water and surface water were collected to provide basic information on the quality and quantity of water resources in northern Bucks County. Ground-water data include descriptions of 1,357 wells and water levels for 28 observation wells measured during 1990-93. Ground-water-quality analyses for 117 wells include physical properties and concentrations of major ions, nutrients, selected metals and other trace constituents, radon, and volatile organic compounds. Surface-water data include chemical analyses of water samples collected at sites on Beaver Creek, Crooks Creek, Geddes Run, Little Tinicum Creek, Paunnacussing Creek, Pidcock Creek, Rapp Creek, Smithtown Creek, and Tinicum Creek.

  7. High-Power Density Design of a Soft-Switching High-Power Bidirectional dc–dc Converter

    Microsoft Academic Search

    Junhong Zhang; Jih-Sheng Lai; Rae-Young Kim; Wensong Yu

    2007-01-01

    A bidirectional dc-dc converter typically consists of a buck and a boost converters. In order to have high-power density, the converter can be designed to operate in discontinuous conducting mode (DCM) such that the passive inductor can be minimized. The DCM operation associated current ripple can be alleviated by interleaving multiphase currents. However, DCM operation tends to increase turnoff loss

  8. PCB integrated inductors for low power DC\\/DC converter

    Microsoft Academic Search

    Matthias Ludwig; Maeve Duffy; T. O'Donnell; P. McCloskey; S. C. O. Mathuna

    2003-01-01

    This paper discusses the use of printed circuit board (PCB) integrated inductors for low power DC\\/DC buck converters. Coreless, magnetic plates and closed core structures are compared in terms of achievable inductance, power handling and efficiency in a footprint of 10 × 10 mm2. The magnetic layers consist of electroplated NiFe, so that the process is fully compatible with standard

  9. State space averaging technique of power converter with digital PID controller

    Microsoft Academic Search

    M. F. N. Tajuddin; N. A. Rahim; I. Daut; B. Ismail; M. F. Mohammed

    2009-01-01

    This paper describes a digital proportional-integral-derivative (PID) controller technique applied to the DC-DC buck converter. The converter is modelled using a state space averaging technique. Due to the non-linear of the power converter, the PID controller is designed to simplify the compensation of the DC-DC converter. The control algorithm is implemented in digital signal processor (DSP) TMS320F2812. The steady state

  10. A power factor corrected PMBLDCM drive for air-conditioner using bridge converter

    Microsoft Academic Search

    Sanjeev Singh; Bhim Singh

    2010-01-01

    This paper aims at a power factor corrected (PFC) buck bridge DC-DC converter for a permanent magnet brushless DC motor (PMBLDCM) for an air conditioner. This PFC converter is fed from a single-phase AC mains through a diode bridge rectifier (DBR) and connected to a voltage source inverter (VSI) feeding the PMBLDCM. The Speed of the proposed PMBLDCM drive is

  11. PID controller implementation in numerical simulation program applied to the power static converter

    Microsoft Academic Search

    Denizar Cruz Martins; R. A. Selinke

    1996-01-01

    This paper presents the analysis and implementation of an algorithm for numerical simulation applied to static power converter, using PWM modulation and PID (proportional integral derivative) controller. A buck power converter prototype is designed and the experimental results are compared to those of the simulation

  12. Modeling of chaotic DC-DC converters by iterated nonlinear mappings

    Microsoft Academic Search

    David C. Hamill; Jonathan H. B. Deane; David J. Jefferies

    1992-01-01

    In parameter ranges where conventional methods break down, DC-DC converters may be described by iterated mappings, a nonlinear discrete modeling technique. The underlying principles are explained and are applied to the example of a PWM-controlled buck converter. Stable behavior and bifurcations to chaos are predicted by numerical evaluation of the governing mapping and are confirmed by experiment

  13. "Le Temps et les temps du Verbe dans Sido" J.P. DUPUY-CIMEOS Dijon Le Temps et les temps du Verbe dans Sido

    E-print Network

    Paris-Sud XI, Université de

    "Le Temps et les temps du Verbe dans Sido" J.P. DUPUY- CIMEOS Dijon page 1/10 Le Temps et les temps plus ouvertement le rôle essentiel du Temps1 . Car l'autobiographie, définie par P. Lejeune comme et par le Temps. C'est lui qui l'autorise -l'autobiographie s'inscrit toujours dans la durée, le

  14. Designing an ultra low quiescent current buck switching regulator

    E-print Network

    Gardner, John Underhill

    2008-01-01

    The new buck regulator proposed in this thesis was designed to operate with only a few micro-amps of supply current during no load output conditions, while maintaining low output voltage ripple. The regulator also has high ...

  15. Analysis of a bi-directional DC-DC converter topology for low power application

    Microsoft Academic Search

    Manu Jain; Praveen K. Jain; Matteo Daniele

    1997-01-01

    This paper describes a bidirectional DC-DC converter for use in low power applications. The converter is based on a half-bridge in the primary side and on a current fed push-pull in the secondary of a high frequency isolation transformer. In the presence of the DC mains (provided by the AC mains), the converter essentially operates in the buck mode charging

  16. Current sharing of paralleled DC-DC converters using GA-based PID controllers

    Microsoft Academic Search

    Chin-hsing Cheng; Po-jen Cheng; Ming-jia Xie

    2010-01-01

    We demonstrate a concept for pulse-width modulation (PWM) control of a parallel DC–DC buck converter, which eliminates the need for multiple physical connections of gating\\/PWM signals among the distributed converter modules. The proposed control concept may lead to easier distributed control implementation of parallel DC–DC converters and distributed power systems.For equipment with significant power requirement, the traditional single power supply

  17. Minimum PCB Footprint Point-of-Load DC-DC Converter Realized with Switched-Capacitor Architecture

    E-print Network

    Sanders, Seth

    Minimum PCB Footprint Point-of-Load DC-DC Converter Realized with Switched-Capacitor Architecture in printed circuit board (PCB) footprint, passive component height and cost when compared to surveyed buck a significant proportion of the overall printed-circuit- board (PCB) area that the converter occupies. As shown

  18. Grouping previously unknown bucks is a stressor with negative effects on reproduction.

    PubMed

    Giriboni, Julia; Lacuesta, Lorena; Damián, Juan Pablo; Ungerfeld, Rodolfo

    2015-02-01

    Grouping previously unknown animals produces social stress, which might have negative effects on reproduction. The aims of the experiment were to determine if grouping unknown bucks (1) triggers a stress response and produces changes in body weight; (2) affects scrotal circumference, testosterone concentration, and semen quality; and (3) has differential effects between resident and introduced bucks. One group of nine Saanen bucks was transported and introduced (introduced bucks, group IG) to a group of eight Saanen bucks (resident bucks, group RG). On day 0, cortisol concentration and rectal temperature were determined, and from day -7 to day 29, body weight, scrotal circumference, and testosterone concentration were recorded and semen quality was determined. The stress response was different between groups: on several moments on day 0, resident bucks had greater cortisol concentration (P?bucks had higher rectal temperature (P?=?0.02). Body weight decreased similarly in both groups from day -7 to day 2 (P?bucks were lighter than RG bucks (P?=?0.05). Also, the reproductive response differed between groups: introduced bucks had lower scrotal circumference (P?bucks was stressful and negatively affected the reproduction, being more serious for the introduced than the resident bucks. PMID:25465221

  19. The victimization of Carrie Buck, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>prologue A girl abandoned by fate Carrie Buck's problems stemmed from her fate as a neglected, poor, uneducated child without defenders.

  20. Request for Change in Meal Plan / Huskie Bucks Fall 20__ / Spring 20__ Spring 20__

    E-print Network

    Karonis, Nicholas T.

    Request for Change in Meal Plan / Huskie Bucks Fall 20__ / Spring 20__ Spring 20__ Please Print one): Fall Semester 20__ / Spring 20__ Spring 20__ Semester Cancel Huskie Bucks Billing Please DO__ / Spring 20__ Spring 20__ Semester Office Use Only

  1. Aquilo que no tem sido dito no debate sobre a "Cincia em crise"

    E-print Network

    Instituto de Sistemas e Robotica

    Aquilo que não tem sido dito no debate sobre a "Ciência em crise" José Manuel Fernandes Extremo últimos dias a experiência de mais uma "zona de J desastre". Desta vez, garante- se, o que está em causa é o futuro da Ciência em Portugal. Como é típico nestas situações, o "consenso" que rapidamente se

  2. John Bell and Carrie Buck, still imageSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck The 17 year-old protagonist of the Buck vs. Bell case, Carrie Buck, was pitted against an array of doctors, lawyers, and eugenicists who were intent on sterilizing her, including John Bell, the superintendent of the Virginia Colony for Epileptics and Feebleminded.

  3. Gertrude Buck on Metaphor: Twentieth-Century Concepts in a Late Nineteenth-Century Dissertation.

    ERIC Educational Resources Information Center

    Vivian, Barbara G.

    Gertrude Buck's doctoral dissertation, published in 1899, represented a radical departure from traditional treatments of metaphor. By approaching metaphor from an entirely new vantage point--psychology--Buck offered fresh insight and provided new explanations for the origin and function of figurative language. Buck made at least four other…

  4. 19. Photocopy of photograph (source uncertain; probably Bucks County Historical ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. Photocopy of photograph (source uncertain; probably Bucks County Historical Society) ca. 1916, photographer unknown SHOWING CONSTRUCTION ESSENTIALLY COMPLETED. MERCER'S CAPTION READS: 'ON SATURDAY EVENING, NOVEMBER 13th AT 5: 15 P.M. THE WORKMEN HAVING AT FIVE O'CLOCK FINISHED THE CONSTRUCTION OF THE NEW BUILDING OF THE MUSEUM OF THE BUCKS COUNTY HISTORICAL SOCIETY AT DOYLESTOWN, A BAND OF TRAVELLING MUSICIANS STOPPED UNASKED AT NO. 196 GREEN STREET OPPOSITE THE SOUTHEAST GABLE OF THE BUILDING AND I HEARD THEM PLAY THE GERMAN SONG SHOWN BELOW, TRANSLATED 'WE HAD BUILT A STATELY HOUSE, AND DEDICATED IT TO GOD, AGAINST RAIN, STORM AND DISASTER' I CALLED THEM BACK TO PLAY IT AGAIN, BUT THEY MISUNDERSTOOD ME AND WENT AWAY. HENRY C. MERCER' - Mercer Museum, Pine & Ashland Streets, Doylestown, Bucks County, PA

  5. Soft switching active snubbers for DC\\/DC converters

    Microsoft Academic Search

    Ahmed Elasser; D. A. Torrey

    1995-01-01

    A soft switching active snubber is proposed to reduce the turn-off losses of the IGBT in a current-mode controlled buck power converter. The soft switching snubber provides zero-voltage switching for the IGBT, thereby reducing the high turn-off losses of the IGBT due to the current tailing. The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary

  6. Autotuning Techniques for Digitally-Controlled Point-of-Load Converters with

    E-print Network

    filter capacitance C and the equivalent series resistance (ESR) can -+PID(z) =K~1z-z)(z -2) - PWM z(z 1) A Programmable PID LCompensator Tuning Algorithm K, z, and z, tuning AID FV Buck Converter L ESR - egout C T i V

  7. Analysis and Modeling of the ZVZCS Full Bridge PWM DC-DC Converter Using a Secondary Auxiliary Circuit

    Microsoft Academic Search

    Yang Xiaobo; Wu Weiyang; Shen Hong

    2005-01-01

    In this paper a novel ZVZCS FB-PWM DC\\/DC converter is analyzed. Comparing with the small signal models of the buck converter and the ZVS-FB PWM converter, the paper indicates that the characters of ZVZCS small signal model are significantly different from the latter. On the basis of small signal modeling, the compensation network is designed and verified by the simulation

  8. SoC Energy Savings = Reduce+Reuse+Recycle: A Case Study Using a 660MHz DC-DC Converter with Integrated Output Filter

    E-print Network

    Lemieux, Guy

    SoC Energy Savings = Reduce+Reuse+Recycle: A Case Study Using a 660MHz DC-DC Converter, mehdia, samad, prp, shahriar } @ ece.ubc.ca Abstract ­ This paper advocates `reduce, reuse, recycle to emphasize reuse and recycling as well. We design a DC-DC buck converter to demonstrate the 3 techniques

  9. Design and analysis of fuzzy logic based robust PID controller for PWM-based switching converter

    Microsoft Academic Search

    Ghulam Abbas; Nacer Abouchi; Awais Sani; Cyril Condemine

    2011-01-01

    This paper presents the design and construction of a fuzzy logic based PID controller for the control of a PWM-based dc-dc buck converter working in Continuous Conduction Mode (CCM). The converter operates at a switching frequency of 500 KHz. Fuzzy Logic Toolbox from MATLAB\\/SIMULINK is used to fuzzify the inputs and their membership functions, express the inference rules linking the

  10. Performance characterization of a high-power dual active bridge DC-to-DC converter

    Microsoft Academic Search

    Mustansir H. Kheraluwala; Randal W. Gascoigne; Deepakraj M. Divan; Eric D. Baumann

    1992-01-01

    The performance of a high-power, high-power-density DC-to-DC converter based on the single-phase dual active bridge (DAB) topology is described. The dual active bridge converter has been shown to have very attractive features in terms of low device and component stresses, small filter components, low switching losses, high power density and high efficiency, bidirectional power flow, buck-boost operation, and low sensitivity

  11. Reduction of power converter EMI emission using soft-switching technique

    Microsoft Academic Search

    H. Chung; S. Y. R. Hui; K. K. Tse

    1998-01-01

    Measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and soft-switched buck, boost, and flyback converters of similar power ratings are presented. Results indicate that EMI emission can be substantially reduced by using a soft-switching technique in power converters. Thus, the soft-switching technique provides a practical and useful solution to reduce EMI emission from switched-mode power circuits. A

  12. buck creek water quality buckcreek.tamu.edu

    E-print Network

    Institute and Texas AgriLife Research worked with the Texas State Soil and Water Conservation Board and cooperating soil and water conservation districts to collect and analyze water samples in Buck Creek. Data AgriLife Extension Service · Donley County Soil and Water Conservation District · Hall-Childress Soil

  13. BUCKS LAKE AND CHIPS CREEK ROADLESS AREAS, CALIFORNIA.

    USGS Publications Warehouse

    Sorensen, Martin L.; Linne, J. Mitchell

    1984-01-01

    The results of a mineral-resource assessment of the Bucks Lake and Chips Creek Roadless Areas, California indicate several areas with mineral-resource potential. The presence or absence of these potentially auriferous deposits can best be determined by drilling through the relatively thin cover of volcanic rocks.

  14. "The Bell Curve" and Carrie Buck: Eugenics Revisited.

    ERIC Educational Resources Information Center

    Smith, J. David

    1995-01-01

    The 1994 publication of "The Bell Curve" by R. Herrnstein and C. Murray is compared to other examples of eugenic principles, including the sterilization of "feebleminded" Carrie Buck, family degeneracy studies focusing on lower class Caucasian families, and other works that view the poorest and least educated members of society as problems for…

  15. Eugenics Past and Present: Remembering Buck v. Bell.

    ERIC Educational Resources Information Center

    Berson, Michael J.; Cruz, Barbara

    2001-01-01

    Provides background information about the eugenics movement. Focuses on eugenics in the United States detailing the case, Buck v. Bell, and eugenics in Germany. Explores the present eugenic movement, focusing on "The Bell Curve," China's one child policy, and the use of eugenic sterilizations in the United States and Canada. Includes strategies…

  16. Matrix converters

    Microsoft Academic Search

    P. W. Wheeler; J. C. Clare; L. Empringham; M. Bland; K. G. Kerris

    2004-01-01

    This paper deals with the vector-controlled MCT matrix converter induction motor drive with minimized commutation time and enchanced waveform quality. It also deals with the design, construction, and testing of a 10-kVA three-phase to three-phase matrix converter induction motor drive. The converter has been built using discrete 65 A metal-oxide-semiconductor (MOS) controlled thyristors (MCTs). The commutation time has been minimized

  17. Research of digital controlled DC/DC converter based on STC12C5410AD

    NASA Astrophysics Data System (ADS)

    Chen, Dan-Jiang; Jin, Xin; Xiao, Zhi-Hong

    2010-02-01

    In order to study application of digital control technology on DC/DC converter, principle of increment mode PID control algorithm was analyzed in the paper. Then, a SCM named STC12C5410AD was introduced with its internal resources and characteristics. The PID control algorithm can be implemented easily based on it. The output of PID control was used to change the value of a variable that is 255 times than duty cycle, and this reduced the error of calculation. The valid of the presented algorithm was verified by an experiment for a BUCK DC/DC converter. The experimental results indicated that output voltage of the BUCK converter is stable with low ripple.

  18. A two-stage converter based controller for a stand alone wind energy system used for remote applications

    Microsoft Academic Search

    Anubhav Sinha; Devesh Kumar; P. Samuel; R. Gupta

    2008-01-01

    This paper proposes a control strategy for tracking and maintaining a constant voltage and frequency across remote loads through stand alone variable speed wind energy conversion system (VSWECS). The system consists of a variable speed wind turbine coupled to a permanent magnet synchronous generator (PMSG). Output of the PMSG is first converted into a fixed DC voltage using a buck

  19. Does a Prosocial-Selfish Distinction Help Explain the Biological Affects? Comment on Buck (1999)

    Microsoft Academic Search

    Jeremy R. Gray

    2002-01-01

    R. Buck (1999) argued that a conceptual distinction between prosocial and selfish motivation is necessary to understand the biological affects (consciously experienced feelings and desires having an innate neurochemical basis). However, at a biological level of analysis, a prosocial-selfish distinction is doubtful empirically and conceptually. For this reason, Buck’s proposed typology of biological affects is unclear. Moreover, a prosocial-selfish distinction

  20. Thermionic converter

    DOEpatents

    Fitzpatrick, G.O.

    1987-05-19

    A thermionic converter is set forth which includes an envelope having an electron collector structure attached adjacent to a wall. An electron emitter structure is positioned adjacent the collector structure and spaced apart from opposite wall. The emitter and collector structures are in a common chamber. The emitter structure is heated substantially only by thermal radiation. Very small interelectrode gaps can be maintained utilizing the thermionic converter whereby increased efficiency results. 10 figs.

  1. Derivation of linearized transfer functions for switching-mode regulations. Phase A: Current step-up and voltage step-up converters

    NASA Technical Reports Server (NTRS)

    Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.

    1981-01-01

    Small-signal models are derived for the power stage of the voltage step-up (boost) and the current step-up (buck) converters. The modeling covers operation in both the continuous-mmf mode and the discontinuous-mmf mode. The power stage in the regulated current step-up converter on board the Dynamics Explorer Satellite is used as an example to illustrate the procedures in obtaining the small-signal functions characterizing a regulated converter.

  2. Photo of Carrie Buck and her mother, Paul Lombardo narratorSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>players The only photograph of Carrie Buck with her mother Emma, taken the day before she would stand trial before the collective onslaught of the American eugenics movement.

  3. The Research of Modeling and Simulation for Phase-shifted Full-bridge ZVS DC \\/ DC Converter

    Microsoft Academic Search

    Hu Xuezhi; Nan Guangqun

    2009-01-01

    On the basis of the analysis of phase-shifted full-bridge ZVS PWM converter, Corresponding small-signal model is build using of state-space averaging method and the traditional Buck circuit model, Thereof, control block diagram of the system and transfer function are derived, Voltage single-loop control system is designed on the basis of small-signal model of phase-shifted full-bridge ZVS converter, Thus, the system

  4. Efficiency modeling and analysis of a switched capacitor converter for a plug-in hybrid electric vehicle energy storage system

    Microsoft Academic Search

    Z. Amjadi; S. S. Williamson

    2009-01-01

    A novel controller for a switched capacitor (SC) bidirectional DC\\/DC converter is proposed for plug-in hybrid electric vehicle energy storage systems, with simultaneous step-up and step-down output voltages. The novel control strategy enables simpler dynamics compared to a standard buck converter with input filter, good regulation capability, lower source current ripple, ease of control, and continuous input current waveform in

  5. PID controller tuning in a DC-DC converter: A geometric approach for minimum transient recovery time

    Microsoft Academic Search

    Santanu Kapat; Philip T. Krein

    2010-01-01

    A high performance proportional-integral-derivative (PID) controller in a dc-dc converter requires a time optimal tuning rule. A suitable auto-tuning rule needs to perform large-signal minimum-time transient recovery, while maintaining a sufficient small-signal stability margin and closed-loop bandwidth. This paper applies a geometric approach to analytically formulate a time optimal PID controller tuning rule for a buck converter. It is shown

  6. Design and implementation of a digital PWM controller for a high-frequency switching DC-DC power converter

    Microsoft Academic Search

    Aleksandar Prodic; Dragan Maksimovic; Robert W. Erickson

    2001-01-01

    This paper describes the complete design and implementation of a digital controller for a high-frequency switching power supply. Guidelines for the minimum required resolution of the analog-to-digital converter, the pulse-width modulator, and the fixed-point computational unit are derived. A design example based on a buck converter operating at the switching frequency of 1 MHz is presented. The controller design is

  7. Master–Slave Current-Sharing Control of a Parallel DC–DC Converter System Over an RF Communication Interface

    Microsoft Academic Search

    Sudip K. Mazumder; Muhammad Tahir; Kaustuva Acharya

    2008-01-01

    Using analog wireless communication, we demonstrate a master-slave load-sharing control of a parallel dc-dc buck converter system, thereby eliminating the need for physical connection to distribute the control signal among the converter modules. The current reference for the slave modules is provided by the master module using radio-frequency (RF) transmission, thereby ensuring even sharing of the load current. The effect

  8. Minimum PCB footprint point-of-load DC-DC converter realized with Switched-Capacitor architecture

    Microsoft Academic Search

    Vincent W Ng; Michael D Seeman; Seth R Sanders

    2009-01-01

    This work reports on the design and test of a CMOS-based switched capacitor (SC) DC-DC conversion integrated circuit (IC) for the point-of-load (POL) application conventionally addressed with the buck converter. A 12V-to-1.5V converter is fabricated in a 0.18 mum technology, with an active die area of 3mm2. There is a significant reduction in printed circuit board (PCB) footprint, passive component

  9. Thermionic converter

    DOEpatents

    Fitzpatrick, Gary O. (Livermore, CA)

    1987-05-19

    A thermionic converter (10) is set forth which includes an envelope (12) having an electron collector structure (22) attached adjacent to a wall (16). An electron emitter structure (24) is positioned adjacent the collector structure (22) and spaced apart from opposite wall (14). The emitter (24) and collector (22) structures are in a common chamber (20). The emitter structure (24) is heated substantially only by thermal radiation. Very small interelectrode gaps (28) can be maintained utilizing the thermionic converter (10) whereby increased efficiency results.

  10. Adaptive control of bucking on harvesters to meet order book constraints

    Microsoft Academic Search

    Glen Murphy; M. Chad Bolding

    2004-01-01

    Modern mechanized harvesters are often fitted with sensors that measure stem dimensions and with computers that optimally buck each stem to maximize the value gained based on stem dimensions, qualities, log prices, and desired specifications. Optimally bucking individual stems, based on market prices, is unlikely to provide yields that meet order book constraints at the harvest unit or forest level.

  11. Biological Determinism and the Concept of Mental Retardation: The Lesson of Carrie Buck.

    ERIC Educational Resources Information Center

    Smith, J. David

    This paper reviews the case of Carrie Buck, who was the first person sterilized (in 1927) under a Virginia law allowing sterilization of persons identified as incompetent and likely to genetically transmit physical, psychological, or social deficiencies to their offspring. This law was later upheld by the Supreme Court in Buck v. Bell, which…

  12. The day before Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>players>Carrie Buck>A cold day in November The day before the Virginia case, Arthur Estabrook photographed Carrie and Emma on a bench located at this spot in the Virginia Colony.

  13. Carrie Buck's last photograph, still image with audioSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck>outcomeThis final picture of Carrie Buck was taken approximately three weeks before she died. She is shown here as Mary in the Christmas pageant at the nursing home where she lived.

  14. Achieving High Efficiency under Micro-Watt Loads with Switching Buck DCDC Converters

    E-print Network

    Rincon-Mora, Gabriel A.

    of system-on-chip (SoC), system-in-package (SiP), and system-on-package (SoP) military, space, medical implants in military, space, medical, and commercial markets fuel the demand for self-sustaining micro

  15. An Ultra-Low-Power Digitally-Controlled Buck Converter IC for Cellular Phone Applications

    E-print Network

    Sanders, Seth

    range of 0.1 to 400 mA. Measured quiescent current in PFM mode is 4 µA. I. INTRODUCTION This paper a cellular phone can sustain with each full charge of the battery, pulse frequency modulation (PFM) mode is preferred for light load operation. The designed IC supports PWM mode for heavy load and PFM mode for light

  16. Fig. 1. A digitally controlled buck converter with ESR zero auto-compensation

    E-print Network

    Prodiæ, Aleksandar

    to insufficient phase margin, noise problems, or even instability. In numerous applications the accurate value. Therefore, in order to meet the regulation requirements, the application engineers usually have to go considering the impact of the capacitor ESR zero. In [10], a sophisticated PID type compensator is designed

  17. Bucking the System in Wyoming: Eliminating Minimum Qualifications and Converting to a "KSA System"

    ERIC Educational Resources Information Center

    Seastedt, Erik

    2003-01-01

    Minimum qualifications, such as possession of an academic degree and a required number of years of work experience, have long been staples of many higher education institutions' hiring practices. However, the University of Wyoming has found that eliminating these minimum qualifications in favor of a hiring system based on knowledge, skills and…

  18. Magnetic emittance suppression using a bucking coil for a dc photocathode electron gun.

    PubMed

    Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki

    2012-12-01

    Magnetic emittance suppression was demonstrated using a bucking coil for a dc photocathode electron gun. The magnetic emittance is derived from a leakage magnetic field on the cathode surface originating from a solenoid lens, and is important for realizing a high brightness dc photocathode electron gun. In order to solve this problem, a bucking coil integrated solenoid lens has been developed. The solenoid lens consists of a main coil, a bucking coil, and a pure iron yoke. The bucking coil and the main coil are integrated in the same yoke in order to prevent distortion of the magnetic field due to misalignment of the two coils. The emittance was measured and calculated as a function of the exciting current of the bucking coil and as a function of the electron beam size on the cathode. PMID:23277978

  19. Magnetic emittance suppression using a bucking coil for a dc photocathode electron gun

    NASA Astrophysics Data System (ADS)

    Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki

    2012-12-01

    Magnetic emittance suppression was demonstrated using a bucking coil for a dc photocathode electron gun. The magnetic emittance is derived from a leakage magnetic field on the cathode surface originating from a solenoid lens, and is important for realizing a high brightness dc photocathode electron gun. In order to solve this problem, a bucking coil integrated solenoid lens has been developed. The solenoid lens consists of a main coil, a bucking coil, and a pure iron yoke. The bucking coil and the main coil are integrated in the same yoke in order to prevent distortion of the magnetic field due to misalignment of the two coils. The emittance was measured and calculated as a function of the exciting current of the bucking coil and as a function of the electron beam size on the cathode.

  20. Discrete time domain modelling and analysis of dc-dc converters with continuous and discontinuous inductor current

    NASA Technical Reports Server (NTRS)

    Iwens, R. P.; Lee, F. C.; Triner, J. E.

    1977-01-01

    Using discrete time state variable representation, a generalized computer-aided modeling and analysis of dc-dc converters is presented. The methodology provides exact modeling and is applicable to all types of power stages and duty-cycle control, including continuous and discontinuous inductor current operation. Converter stability, transient behavior and audio susceptibility can be analytically evaluated and predicted. The generalized theory of the proposed approach to converter modeling and analysis is presented first, followed by a demonstrative example applying the theory to a constant frequency buck converter operating in continuous and discontinuous inductor current mode. Excellent agreement with laboratory test data has been observed.

  1. Modeling and simulation of switched capacitor converters for electric vehicle energy storage systems

    Microsoft Academic Search

    Zahra Amjadi; Sheldon S. Williamson

    2010-01-01

    This paper presents the analysis and novel controller design for a hybrid 4-quadrant (4-Q) switched-capacitor (SC) Luo and a conventional buck-boost bidirectional DC\\/DC converters, for HEV\\/PHEV energy storage system applications, based on power of traction motor and battery current gradient. Features of voltage step-down, voltage step-up, and bi-directional power flow are integrated into a single circuit. The novel hybrid controller

  2. A low-voltage CMOS DC-DC converter for a portable battery-operated system

    Microsoft Academic Search

    Anthony J. Stratakos; Seth R. Sanders; Robert W. Brodersen

    1994-01-01

    Motivated by emerging battery-operated applications that demand compact, lightweight, and highly efficient DC-DC power converters, a buck circuit is presented in which all active devices are integrated on a single chip using a standard 1.2 ? CMOS process. The circuit delivers 750 mW at 1.5 V from a 6 V battery. To effectively eliminate switching loss at high operating frequencies,

  3. How Buck vs. Bell began, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of carrie buck>trial Amherst County Courthouse Amherst County Courthouse was the first step of a legal case that would lead all the way to the Supreme Court.

  4. The rape of Carrie Buck, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>epilogue Carrie was raped After raping Carrie, Clarence Garland left Charlottesville rather than fulfill his promise to marry her.

  5. Harry Laughlin at Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>trial Harry Laughlin's deposition Harry Laughlin, superintendent of the Eugenics Record Office, provided a written deposition based on language given to him by doctors at the Virginia Colony.

  6. Lies at Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>epilogue A case built on falsehoods Although Carrie was not feebleminded or morally degenerate, this was the way she was portrayed by the lawyers.

  7. The death of Emma Buck, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>epilogue Emma never came home Although she tried several times, Carrie was never able to bring her mother Emma home from the Virginia Colony.

  8. Application of digital control techniques for satellite medium power DC-DC converters

    NASA Astrophysics Data System (ADS)

    Skup, Konrad R.; Grudzinski, Pawel; Nowosielski, Witold; Orleanski, Piotr; Wawrzaszek, Roman

    2010-09-01

    The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DC converters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.

  9. Switching Power Converter A/D Converters

    E-print Network

    Controller Health Monitoring Efficiency Monitoring Frequency Response Monitoring Health Monitoring Sensing Points Figure 1. System architecture for health monitoring test-bed. Converter parameters are sensed then displays processed data concerning the converter health status. Online Health Monitoring in Digitally

  10. Bucking Coil Efficiency Correction for 5'' PMT Exposed to an External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Llodra, Anthony; Reinhold, Joerg

    2014-03-01

    This research was conducted in support of the Hall C upgrade activities at Thomas Jefferson National Accelerator Facility (JLab). We propose to employ bucking coils in order to maximize the collection efficiency of the 5'' PMTs installed on the Cherenkov detector, which could potentially be exposed to external magnetic field produced by the Super Conducting Super High Momentum Spectrometer (SHMS) magnet. In this research project a 5'' PMT was placed in a light tight cylinder with a fiber optic cable. The cylinder was centered within a set of Helmholtz coils to produce a constant external magnetic field. Furthermore, the cylinder was wrapped with 20 coils of standard 12 gauge cable to act as the bucking coil. With the intensity of the LED source, and the magnitude of the external magnetic field fixed at a carefully determined value, data was taken to determine if the collection efficiency of the PMT was indeed affected. With a decrease in collection efficiency confirmed, further data were taken. A range of current (0-6 A) was applied to the bucking coils, while ADC spectra were analyzed in intervals of 0.25 A. The data indicated that in an external magnetic field of approximately 3 Gauss, the 5'' PMT collection efficiency is maximized with the bucking coil current set to approximately 3.5 A. Thus, the data conclusively indicates that the bucking coil system will indeed maximize the collection efficiency of the 5'' PMT. Florida International University.

  11. Science and Democracy : Lessons from Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>prologue Fragility of American freedoms Carrie Buck, who was stripped of her right to reproduce, was born only blocks away from Jefferson's rotunda at the University of Virginia, a symbol of American freedom.

  12. Semen characteristics and sperm morphological studies of the West African Dwarf Buck treated with Aloe vera gel extract

    PubMed Central

    Olugbenga, Oyeyemi Matthew; Olukole, Samuel Gbadebo; Adeoye, Ajayi Tolulope; Adejoke, Adeniji Deborah

    2011-01-01

    Background: Aloe vera (Aloe barbadensis miller) is an evergreen perennial plant widely used in modern herbal practice and is often available in proprietary herbal preparations. Objective: This study was designed to investigate the semen picture and spermatozoa morphology of West African Dwarf (WAD) bucks treated with Aloe vera extract. Materials and Methods: Twelve sexually matured WAD bucks, weighing between 11 and 15 kg, were used for the study. The bucks were first used as control (pre-treatment) and later as two groups of six animals each. The first six bucks received 10 mls of the 3% extract while the other six received 10 mls of the 4% of the extract for a 7 day period. Semen was collected from both the 3 and 4% extract treated bucks for the control (pre-treatment), on days eight (first week post-treatment) and fifteen (second week post-treatment) in each case using the electroejaculation method. The spermiogram of the bucks were investigated using standard procedures. Data obtained were analyzed using two way ANOVA and significance reported at p<0.05. Results: The continuous administration of Aloe vera extract significantly (p<0.05) reduced sperm concentration, motility and percentage livability and resulted in increased sperm abnormalities in the WAD buck. Conclusion: Aloe vera adversely affected the spermiogram of bucks. The plant can reduce fertility in male animals and is therefore not recommended for medicinal purpose in male animals especially those used for breeding. PMID:25587252

  13. A Soft-Switched Full-Bridge Single-Stage AC-to-DC Converter With Low-Line-Current Harmonic Distortion

    Microsoft Academic Search

    A. K. S. Bhat; R. Venkatraman

    2005-01-01

    A single-phase high-frequency transformer-isolated soft-switching single-stage ac-to-dc converter with low-line-current distortion is presented. The circuit configuration is obtained by integrating two discontinuous current mode (DCM) boost converters with a DCM full-bridge buck converter. The zero-voltage switching for the top switches is achieved automatically, whereas bottom switches are aided by zero-voltage transition circuits. The output voltage is regulated by duty-cycle control

  14. Carrie Buck roadside marker, still imageSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck>epilogue In May 2, 2002, the 75th anniversary of the Supreme Court decision on Buck v. Bell, Virginia Governor Mark Warner publicly apologized for Virginia's past involvement in eugenics. He said, "The eugenics movement was a shameful effort in which state government never should have been involved." The State of Virginia approved a roadside marker in memory of Carrie in her hometown of Charlottesville. The governors of California, Oregon, North Carolina, and South Carolina also issued apologies.

  15. Barberton drilling project - Buck Reef Chert core BARB3

    NASA Astrophysics Data System (ADS)

    Hofmann, Axel; Karykowski, Bartosz; Mason, Paul; Chunnet, Gordon; Arndt, Nick

    2013-04-01

    As part of the ICDP-sponsored Barberton drilling project a single drill core (BARB3) with a total length of 899 m was obtained from the c. 3.4 Ga old Buck Reef Chert (BRC). The BRC is an unusually thick (up to 350 m) sequence of predominantly black-and-white banded chert and banded ferruginous chert that are steeply dipping. It overlies a shallow intrusive to extrusive sequence of dacitic volcanic rocks of the Hooggenoeg Formation and is separated from ultramafic lapillistone of the Kromberg Formation by a >150 m thick ultramafic sill. Drilling commenced in the ultramafic sill at an angle of c. 45° and c. 200 m of serpentinized peridotite were intersected. The remaining c. 700 m of the core include a great variety of chert lithofacies and minor intrusive mafic to intermediate igneous rocks. The base of the BRC was not intersected. Geophysical logging was done up to a depth of 847 m and included acoustic televiewer, gamma ray, resistivity, magnetic field and caliper logs. Stratigraphic and geophysical logs will be presented that will form the basis of follow-up studies on the BARB3 core. Abundance of organic matter, sulphides and Fe-bearing carbonates in specific intervals or associated with specific facies of the chert succession reflect changes in the oceanic, environmental and/or hydrothermal conditions in a shallow marine early Archaean setting. Evaluating the different processes will require a combined sedimentological, mineralogical, and geochemical approach that will provide insights into the habitat of early life, geochemical cycles and marine/hydrothermal conditions.

  16. Design and test of a novel buck-boost inverter with three switching devices

    Microsoft Academic Search

    Yonggao Zhang; Abraham Tareke Woldegiorgis; Liuchen Chang

    2012-01-01

    A novel buck-boost inverter with three switching devices appropriate for small renewable energy applications was proposed. Operating principles, four different operating modes and pulse energy modulation (PEM) method under discontinuous inductor current conduction mode are discussed in this paper. It also describes the design of hardware, such as the power circuit, flyback transformer and control circuit, and the design of

  17. Protection against Buck Damage in Blackwood (Acacia melanoxylon) \\/ Beskerming Teen Bokke in Jong “Blackwood” (Acacia Melanoxylon)

    Microsoft Academic Search

    J. G. de Zwaan

    1977-01-01

    In order to protect young blackwood transplants from browsing by buck, some psychological, chemical and mechanical protection measures were tested. All these measures, except for the mechanical ones, were completely unsatisfactory. Surrounding each individual plant by a tube of plastic mesh or wire netting, although expensive, practically eliminated any browsing damage.

  18. MAKING A BUCK IN THE CATTLE BUSINESS THE VETERINARIANS ROLE Max Irsik DVM, MAB

    E-print Network

    Watson, Craig A.

    MAKING A BUCK IN THE CATTLE BUSINESS THE VETERINARIANS ROLE Max Irsik DVM, MAB University of Florida College of Veterinary Medicine Gainesville Fl 32610-0136 Veterinarians working with beef cattle a significant impact on price. Veterinarians working with beef cattle producers should provide management

  19. Follow-up Study; Non-academic Attrition at Bucks County Community College, 1965-1972.

    ERIC Educational Resources Information Center

    Bucks County Community Coll., Newtown, PA. Office of Institutional Research.

    In this follow-up study, information was obtained regarding the educational and employment patterns of students who withdrew from Bucks County Community College, their reasons for withdrawing, and their evaluation of the college's programs and services. The questionnaire used (a copy of which is provided in an appendix) was similar to the one used…

  20. Explores Dam Removal Located in Southwest Ohio, Buck Creek and its

    E-print Network

    Bogaerts, Steven

    OHIO Researcher Explores Dam Removal Located in Southwest Ohio, Buck Creek and its tributary, Beaver Creek, run through a series of low-head dams in Springfield, Ohio. Historically, the four dams of the four dams. This will help restore the natural flow of sediments and fish along the entire river

  1. No boundaries. Texas' Christus Health bucks trend by looking to Mexico for expansion.

    PubMed

    Jaklevic, M C

    2001-08-01

    Christus Health has bucked the trend by looking to Mexico for expansion. The Roman Catholic system based in Irving, Texas, bought 51% of Hospital Muquerza in the prosperous northern Mexico state of Nuevo Leon. Christus believes the move makes sense on many levels. PMID:11507863

  2. Operation principles of bi-directional full-bridge DC\\/DC converter with unified soft-switching scheme and soft-starting capability

    Microsoft Academic Search

    Kunrong Wang; Fred C. Lee; Jason Lai

    2000-01-01

    A new bi-directional dual full-bridge DC\\/DC converter with a unified soft-switching scheme and soft-start capability is proposed in this paper. A simple voltage clamp branch is used to limit transient voltage across the current-fed bridge and realize zero-voltage-switching (ZVS) in boost mode operation, while achieving hybrid zero-voltage\\/zero-current switching (ZVZCS) for the voltage-fed bridge in buck mode operation. The theory of

  3. Thermoacoustic Space Power Converter

    Microsoft Academic Search

    Emanuel Tward; Michael Petach; Scott Backhaus

    2003-01-01

    A thermoacoustic power converter for use in space in the conversion of radioisotope-generated heat to electricity is under development. The converter incorporates a thermoacoustic driver that converts heat to acoustic power without any moving parts. The acoustic power is used to drive a pair of flexure bearing supported pistons connected to voice coils in a vibrationally balanced pair of moving

  4. Convertible Bonds as \\

    Microsoft Academic Search

    Jeremy C. Stein

    1992-01-01

    This paper argues that corporations may use convertible bonds as an indirect (albeit possibly risky) method for getting equity into their capital structures in situations where adverse selection problems make a conventional stock issue unattractive. Unlike other theories of convertible bond issuance, the model of this paper highlights: 1) the importance of call provisions on convertibles; and 2) the significance

  5. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Gill, J. C.; Earle, R. V.; Mar, H. M.

    1982-01-01

    The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988.

  6. Two novel soft-switched, high frequency, high-efficiency, non-isolated Voltage Regulators-the phase-shift buck converter and the matrix-transformer phase-buck converter

    Microsoft Academic Search

    Jia Wei; Fred C. Lee

    2005-01-01

    Microprocessors in today's computers continue to get faster and more powerful. From the Intel 80×86 series to today's Pentium IV, CPUs have greatly improved the performance. Accordingly, their power consumption has increased dramatically , . To reduce the power loss, an evolution began when the high-performance Pentium processor was driven by a nonstandard, less-than-5-V power supply, instead of drawing its

  7. Carrie Buck's lawyer working against her interests, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>epilogue Betrayal by her attorney Carrie's lawyer, Irving Whitehead, colluded with lawyers representing the Virginia Colony to help insure that the case went to the Supreme Court.

  8. Effect of zeranol or melengestrol acetate (MGA)on testicular development and aggression in farmed fallow bucks

    E-print Network

    Wilson, Timothy Wayne

    2000-01-01

    . Neither body weight nor condition score were affected (P>.10) by treatment. Scrotal circumference (SC) and paired testis volume (PTV) were affected by day x treatment interaction (Ptestes of zeranol bucks being smaller compared to those...

  9. The impact of the Buck vs. Bell trial, Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>Outcome Sterilization's unknowing victims Although the Virginia statute included safeguards, many people deemed "unfit" were sterilized without their knowledge.

  10. Estimation of Bidirectional Buck\\/boost DC\\/DC Converters with Electric Double-Layer Capacitors for Energy Storage Systems

    Microsoft Academic Search

    Shigeyuki Funabiki; Masayoshi Yamamoto

    2009-01-01

    Renewable energy such as wind force and solar light has collected the attention as alternative energy sources of fossil fuel. An energy storage system with an electric double-layer capacitor (EDLC), which balances the demand and supply power, is required in order to introduce the electric power generating system that utilizes renewable energy. Currently, the research and development of these energy

  11. Interleaved power converter

    DOEpatents

    Zhu, Lizhi (Canton, MI)

    2007-11-13

    A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DC converters with three rather than four high voltage inverter legs.

  12. ITER convertible blanket evaluation

    SciTech Connect

    Wong, C.P.C.; Cheng, E.

    1995-09-01

    Proposed International Thermonuclear Experimental Reactor (ITER) convertible blankets were reviewed. Key design difficulties were identified. A new particle filter concept is introduced and key performance parameters estimated. Results show that this particle filter concept can satisfy all of the convertible blanket design requirements except the generic issue of Be blanket lifetime. If the convertible blanket is an acceptable approach for ITER operation, this particle filter option should be a strong candidate.

  13. GraphicConverter

    NSDL National Science Digital Library

    GraphicConverter goes beyond the ability to convert a large number of graphic file formats. It provides tools for the creation and/or editing of graphics, animations, movies, and slide presentations; it also supports Adobe Photoshop compatible plug-ins. Currently, GraphicConverter can import 96 different graphic file formats and export 38. Conversion of several files (graphic or text) at a time is also possible through the "convert more..." feature. The tools offered for graphic editing are Photoshop-like. Detailed documentation is provided. This Macintosh shareware is provided by Lemke Software.

  14. Buck family pedigree (detail), still imageSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck>trialDetail of Harry Laughlin's pedigree of the Buck famiiy. Although it was a bona fide medical diagnosis in its day, "feeblemindedness" had virtually no clinical meaning and is no longer used in medical terminology. Many people who were classified as feebleminded would now be called mildly retarded, learning disabled, or simply underachievers. Contrary to the evidence presented at her trial, Carrie appears to have had no serious mental problem, and she was not promiscuous. Vivian's conception was the result of Carrie's rape by Clarence Garland, the nephew of her foster parents. Carrie, like many unwed mothers of that time, was institutionalized to prevent shame to the family.

  15. Bucked Coils lattice: a novel ionisation cooling lattice for the Neutrino Factory

    NASA Astrophysics Data System (ADS)

    Alekou, A.; Pasternak, J.

    2012-08-01

    A successful muon ionisation cooling channel for the Neutrino Factory and Muon Collider, requires simultaneously a strong focusing and a large mean RF gradient. To date, all candidate design lattices achieved these requirements with a large magnetic field in the RF cavities, which can potentially limit the achievable gradient leading to RF breakdown. This paper presents the Bucked Coils lattice, designed to reduce the magnetic field at the RF cavities while achieving a satisfactory cooling effect and muon transmission. The Bucked Coils managed to achieve significantly reduced magnetic field components at the RF position, while also achieving a comparable transmission to the FSIIA lattice, the current reference ionisation cooling lattice of the Neutrino Factory. A detailed comparison with respect to the magnetic field reduction, cooling dynamics and transmission is given. A preliminary feasibility study taking into account the hoop stress of the coils and their superconducting operation is also presented.

  16. The microminiature thermionic converter

    Microsoft Academic Search

    Donald Bryan King

    2000-01-01

    The design, fabrication, testing, and analysis of the microminiature thermionic converter (MTC) is discussed. MTCs are two electrode devices that convert heat energy into electrical energy. The electrodes are spaced opposite each other in a vacuum environment with one electrode heated and the second cooled. Electrons are emitted from the hot electrode to the cool electrode creating electrical power. The

  17. Nanoscale energy converters

    NASA Astrophysics Data System (ADS)

    Linke, Heiner

    2013-03-01

    An overview is given of the types of energy converters considered by this symposium: systems that make use of nanoscale phenomena and nanotechnology to achieve higher conversion efficiency, to achieve qualitatively enhanced performance, or to access new energy resources. The focus is on general concepts and principles, and approaches used by several nanoscale energy converters are identified.

  18. Photocapacitive image converter

    NASA Technical Reports Server (NTRS)

    Miller, W. E.; Sher, A.; Tsuo, Y. H. (inventors)

    1982-01-01

    An apparatus for converting a radiant energy image into corresponding electrical signals including an image converter is described. The image converter includes a substrate of semiconductor material, an insulating layer on the front surface of the substrate, and an electrical contact on the back surface of the substrate. A first series of parallel transparent conductive stripes is on the insulating layer with a processing circuit connected to each of the conductive stripes for detecting the modulated voltages generated thereon. In a first embodiment of the invention, a modulated light stripe perpendicular to the conductive stripes scans the image converter. In a second embodiment a second insulating layer is deposited over the conductive stripes and a second series of parallel transparent conductive stripes perpendicular to the first series is on the second insulating layer. A different frequency current signal is applied to each of the second series of conductive stripes and a modulated image is applied to the image converter.

  19. On a new method of tipping buck gauge calibration at HMS

    NASA Astrophysics Data System (ADS)

    Morvai, Krisztián; Nagy, Zoltán

    2013-04-01

    The knowledge of precipitation distribution is of great importance for meteorological applications (numerical weather prediction, agrometeorology, climatology). The variation and distribution of precipitation are on a wide scale that requires high density of measurements. HMS has a precipitation ground measurement system of 100 tipping buck gauges. All tipping buck gauges are of the same manufacturer (Lambrecht) and are maintained and calibrated regularly. Firstly the calibration method of tipping buck gauges applied at HMS and the relevant statistics are introduced such as distribution and sources of measurement errors. New requirements arose against the existing calibration method after it was studied. As the precipitation measurement is based on weight measurement during the calibration it is important to provide tipping the specified weight precisely to the gauges. The best way is the controlled closure of the reference interrupting the tipping procedure. This leads to the purchase of new, precise, more accurate scales as well as to some other developments. The explicitly controlled changeability of tipping intensity - that affects the precision of measurements - also came to a solution with multiple closures introduced. Other changes were also made on the calibration procedure to facilitate the work. Secondly the newly introduced changes and developments by the authors and their effects on calibration are briefly described.

  20. Cascaded resonant bridge converters

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A. (Inventor)

    1989-01-01

    A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.

  1. Homosexual behavior in male goats is more frequent during breeding season and in bucks isolated from females.

    PubMed

    Ungerfeld, Rodolfo; Giriboni, Julia; Freitas-de-Melo, Aline; Lacuesta, Lorena

    2014-05-01

    Male homosexual behavior is observed in many ruminant species; seasonality and isolation from females may affect the display of male-male sexual behavior. Our objectives were to determine whether: 1) homosexual behavior has a seasonal pattern in male goats (Capra hircus); 2) isolation from female goats influences the frequency of the display of homosexual behavior; and 3) the frequency of homosexual behaviors is related to testosterone concentration. Bucks were housed in a pen adjacent to another pen with 3 estrous goats (FC group) or in complete isolation from females (IF group). Homosexual behaviors and testosterone concentrations were recorded in October, December, February and May. Frequencies of penile display and flehmen increased in May and were observed more frequently in the IF than in the FC group. Ano-genital sniffing was more frequent in February and May and was more frequent in IF than in FC bucks. Lateral approaches were more frequent in May, in which period this was more frequently observed in IF bucks. Mount attempts and mounts were only observed in IF bucks. Testosterone concentrations increased from December to February and decreased in May, although they were still greater than in October and December. In May IF bucks had greater testosterone concentrations than FC bucks. Testosterone concentrations were only related to the number of lateral approaches in IF bucks in December. In conclusion, homosexual behavior was more frequent during the late breeding season than during the early and the non-breeding seasons, and in males isolated from females than in males housed near estrous females. Testosterone concentrations appear to be unrelated to homosexual behavior. PMID:24792347

  2. Thermoacoustic Space Power Converter

    NASA Astrophysics Data System (ADS)

    Tward, Emanuel; Petach, Michael; Backhaus, Scott

    2003-01-01

    A thermoacoustic power converter for use in space in the conversion of radioisotope-generated heat to electricity is under development. The converter incorporates a thermoacoustic driver that converts heat to acoustic power without any moving parts. The acoustic power is used to drive a pair of flexure bearing supported pistons connected to voice coils in a vibrationally balanced pair of moving coil alternators. Initial tests of the small ~100W thermoacoustic driver have demonstrated good efficiency. An alternator matched to the driver is now under construction. A description of the system and the results of development tests are presented.

  3. Microminiature thermionic converters

    DOEpatents

    King, Donald B. (Albuquerque, NM); Sadwick, Laurence P. (Salt Lake City, UT); Wernsman, Bernard R. (Clairton, PA)

    2001-09-25

    Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

  4. Fluorescent radiation converter

    NASA Technical Reports Server (NTRS)

    Viehmann, W.

    1980-01-01

    Fluorescent radiation converter used optically transparent substrate. One side of substrate is coated with plastic film containing fluorescent organic dyes that absorb optical radiation at one wavelength and emit it at longer one. Coating is formulated to respond to specific wavelengths. Emitted radiation is reflected internally inside substrate, amplifying intensity that reaches radiation detector. Converter can be made in several shapes and size; round and square bars coated all round their lengths are useful in converting relatively intense radiation and transmitting it through substrate over lengthy distances.

  5. Em 1959 cursava o terceiro colegial no Julinho em Porto Alegre, onde recebi o folheto "Voc tem pensado em fsica?" que mais tarde soube ter sido produzido

    E-print Network

    dos Santos, C.A.

    Em 1959 cursava o terceiro colegial no Julinho em Porto Alegre, onde recebi o folheto "Você tem pensado em física?" que mais tarde soube ter sido produzido pelo Darcy. Estava indeciso entre física e som e a cores a bela tarde em que, dentro de um bonde Petrópolis, passando pela Protásio diante do

  6. Thermionic photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, D. L. (inventor)

    1985-01-01

    A thermionic photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or gallium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

  7. Gallium phosphide energy converters

    Microsoft Academic Search

    P. E. Sims; L. C. Dinetta; M. A. Goetz

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need

  8. Multilevel converters-a new breed of power converters

    Microsoft Academic Search

    Jih-Sheng Lai; Fang Zheng Peng

    1996-01-01

    Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of DC capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels

  9. Physiological Response of Rabbit Bucks to Dietary Fumonisin: Performance, Haematology and Serum Biochemistry

    Microsoft Academic Search

    Emmanuel O. Ewuola; Francis A. Gbore; Jacob T. Ogunlade; Ranajit Bandyopadhyay; John Niezen; Gabriel N. Egbunike

    2008-01-01

    Maize grains contaminated with fumonisin, a metabolite of Fusarium\\u000a verticillioides was incorporated into matured male rabbits’ diet to evaluate its effects on performance, haematology and serum biochemistry\\u000a in rabbits. Thirty individually caged crossbred adult rabbit bucks averaging 1.36 ± 0.01 kg (about 22–24-week-old) were randomly\\u000a allotted to three treatment diets comprising a control diet (containing 0.35 ± 0.02 mg fumonisin\\/kg) and two test diets containing\\u000a 12.30 ± 0.16 and

  10. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

    Goldstein, D. N.; Hirschkron, R.; Smith, C. E.

    1983-01-01

    Convertible propulsion systems for advanced rotorcraft are evaluated in terms of their impact on aircraft operating economics and fuel consumption. A variety of propulsion system concepts, including separate thrust and power producing engines, convertible fan/shaft engines, and auxiliary propeller configurations are presented. The merits of each are evaluated in two different rotorcraft missions: an intercity, commercial transport of the ABC(TM) type, and an offshore oil ring supply ship of the X-wing type. The variable inlet guide vane fan/shaft converting engine and auxiliary propeller configurations are shown to offer significant advantages over all the other systems evaluated, in terms of both direct operating cost and fuel consumption.

  11. Thermionic energy converter investigations

    NASA Technical Reports Server (NTRS)

    Goodale, D. B.; Lee, C.; Lieb, D.; Oettinger, P. E.

    1979-01-01

    This paper presents evaluation of a variety of thermionic converter configurations to obtain improved efficiency. A variable-spacing diode using an iridium emitter gave emission properties comparable to platinum, but the power output from a sintered LaB6 collector diode was not consistent with its work function. Reflectivities above 0.5 were measured at thermal energies on oxygenated-cesiated surfaces using a field emission retarding potential gun. Performance of converters with structured electrodes and the characteristics of a pulsed triode were studied as a function of emitter, collector, cesium reservoir, interelectrode spacing, xenon pressure, and pulsing parameters.

  12. Converting triangulations to quadrangulations

    Microsoft Academic Search

    Suneeta Ramaswamia; Pedro Ramos; Godfried Toussaint

    1995-01-01

    We study the problem of converting triangulated domains to quadrangulations, under a variety of constraints. We obtain a variety of characterizations for when a triangulation (of some structure such as a polygon, set of points, line segments or planar subdivision) admits a quadrangulation without the use of Steiner points, or with a bounded number of Steiner points. We also investigate

  13. Catalytic Converters and Nanocatalysts

    NSDL National Science Digital Library

    This lab, presented by the National Nanotechnology Infrastructure Network, covers the concept of chemical reactions. Students will learn about "the reactions involved in catalytic converters and the importance of nanocatalysts in the reactions." Teacher Preparation Guides, Student Guides, and Next Generation Science Standards applicable to the lesson are included.

  14. Hydro current energy converter

    Microsoft Academic Search

    Rauch

    1985-01-01

    A hydro-dynamic device for capturing the energy of a natural stream of flowing water, and converting such current or flow of water energy into electric power for user consumption. The device has a primary tubular housing, a sealed, conical, secondary housing containing an electrical generator. The secondary housing has a conical end portion, and is disposed within and along the

  15. Performance study of the Bucked Coils cooling lattice for the Neutrino Factory

    NASA Astrophysics Data System (ADS)

    Alekou, A.; Pasternak, J.; Rogers, C.

    2013-02-01

    In a Neutrino Factory (NF), neutrinos are produced from the decays of muons. The muon beam itself is produced with large emittance at the NF front-end and in order to be efficiently transported to downstream accelerator systems, the beam emittance needs to be cooled using ionisation cooling. The reference ionisation cooling channel of the NF reduces the transverse emittance by a factor of ~3. However, this lattice has a large magnetic field at the position of the RF cavities and therefore its feasibility has come under question when recent studies indicated high external magnetic field may lower the maximum achievable gradient of the RF cavities. The present work summarizes the performance of a new lattice named "Bucked Coils", designed to mitigate the magnetic field issue of the reference lattice of the NF while aiming to achieve similar cooling performance and transmission. This new lattice offers solution by reducing the longitudinal component of the magnetic field to almost 0 T while at the same time achieving a transmission comparable to the reference lattice within the transverse acceptance of 30 mm. Detailed comparison between the Bucked Coils lattice and the reference lattice of the NF follows with respect to the magnetic field reduction, cooling performance and transmission.

  16. Contributions to the Lichen Flora of Pennsylvania: The Lichen Flora of the Diabase Region of Northern Bucks and Montgomery Counties

    Microsoft Academic Search

    JAMES C. LENDEMER

    This preliminary checklist of lichens and lichenicolous fungi occurring in the diabase region of northern Bucks and Montgomery Counties, Pennsylvania, USA, includes a total of 72 taxa, of which ten have not previously been reported from the state. The range of Lecanora oreinoides (Körber) Hertel & Rambold, is extended to include Connecticut, Massachusetts, and Pennsylvania.

  17. Influence of dietary zinc on semen traits and seminal plasma antioxidant enzymes and trace minerals of beetal bucks.

    PubMed

    Rahman, H U; Qureshi, M S; Khan, R U

    2014-12-01

    Zinc (Zn) is a potent antioxidant and plays a key role in scavenging free radicals. We hypothesized that supplementation of Zn would reduce the oxidative damage, which is linked with poor sperm quality. Sixteen bucks of similar average age (2 years) and body weight (41 kg) were randomly divided into four groups viz., 1, 2, 3 and 4 supplemented with zinc sulphate into the diet at the rate of 0, 50, 100 and 200 mg/buck/day, respectively, for 3 months. At the end of the experiment, semen samples were collected and assessed. Seminal plasma was separated to find the concentration of superoxide dismutase (SOD), glutathione peroxidase (GPx), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and trace minerals (Zn, Cu, Mn and Fe). The results revealed that semen volume (1.85 ± 0.01 ml) and sperm motility (88.23 ± 5.77%) increased significantly (p < 0.05) in supplemented groups compared with the control specifically in group 3. SOD (10.66 ± 0.23 inhibition rate %) and GPx (23.55 ± 0.49 mU/ml) increased significantly (p < 0.05) in group 3 with no effect on AST and ALT. Among seminal plasma trace elements, no significant change (p > 0.05) was observed. From the present results, we concluded that zinc sulphate at the rate of 100 mg/buck/day improved semen traits and seminal plasma antioxidant capacity in Beetal bucks. PMID:25263460

  18. Nutrient Intake and Digestibility of West African Dwarf Bucks Fed Poultry Waste-Cassava Peels Based Diets

    Microsoft Academic Search

    A. I. Ukanwoko; J. A. Ibeawuchi

    2009-01-01

    The effect of feeding poultry waste-cassava peel based diets on the nutrient intake and digestibility were evaluated using four West African Dwarf (WAD) bucks. The animals were confined individually in metabolism cages and offered the treatment diets (A-D) in a 4 x 4 Latin Square Design. The diets were formulated from poultry waste, cassava peel, palm kernel cake, molasses, bone

  19. The Economic Impact of Bucks County Community College on the Local Economy During Fiscal Year 1978-79.

    ERIC Educational Resources Information Center

    Mahon, Jack

    The effects of Bucks County Community College (BCCC) on the local economy during fiscal year (FY) 1979 were investigated in terms of the monies spent in operating BCCC through purchases of goods and services, salaries to college employees, student financial aid expenditures, veterans' benefits, and property taxes paid by college employees, as well…

  20. Retraction of the mobile descended larynx during groaning enables fallow bucks (Dama dama) to lower their formant

    E-print Network

    Nottingham, University of

    Retraction of the mobile descended larynx during groaning enables fallow bucks (Dama dama) to lower Abstract A permanently descended larynx is found in humans and several other species of mammals. In addition to this, the larynx of species such as fallow deer is mobile and in males it can be retracted

  1. Mate choice in rocky mountain mule deer bucks (Odocoileus hemionus hemionus): is there a preference for does without fawns?

    Microsoft Academic Search

    Susan W. Margulis

    1993-01-01

    The present study investigates the prediction that, given the energy-intensive nature of male courtship and rutting behavior in mule deer, bucks will preferentially mate with those does most likely to breed successfully. Does without fawns in a given breeding season are in better physical condition and are more likely to rear fawns conceived in the current breeding season than are

  2. Multilevel converters -- A new breed of power converters

    SciTech Connect

    Lai, J.S. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.; Peng, F.Z. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)

    1995-09-01

    Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. The techniques to balance the voltage between different levels normally involve voltage clamping or capacitor charge control. There are several ways of implementing voltage balance in multilevel converters. Without considering the traditional magnetic coupled converters, this paper presents three recently developed multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded-inverters with separate dc sources. The operating principle, features, constraints, and potential applications of these converters will be discussed.

  3. Thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (inventor)

    1983-01-01

    The efficiency of thermionic energy converters is improved by internal distribution of tiny sorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. The tiny, sorted diode distribution comprises protrusions of the emitter material from the main emitter face which contact the main collector face thermally but not electrically. The main collector ends of the protrusions are separated from the main collector by a thin layer of insulation, such as aluminum oxide. The shorted tiny diode distribution augments cesium ionization through internal thermal effects only within the main diode. No electrical inputs are required. This ionization enhancement by the distribution of the tiny shorted diodes not only reduces the plasma voltage drop but also increases the power output and efficiency of the overall thermionic energy converter.

  4. Converting Informix 4GLApplications to Informix Genero Why Convert?

    E-print Network

    Converting Informix 4GLApplications to Informix Genero Why Convert? Your Informix 4GL applications. This is normal; your forms layouts respect the structure of IBM® Informix® 4GL. With a few minor modifications will be a state-of-the-art graphical application. Considerations for Converting I-4GL/D-4GL to Informix Genero

  5. Numerical study of a bucked-coil system for muon transport and cooling

    NASA Astrophysics Data System (ADS)

    Stratakis, Diktys; Alekou, Androula; Neuffer, David; Pasternak, Jaroslaw; Rogers, Chris T.

    2012-12-01

    A Neutrino Factory, which can deliver an intense flux of ˜1021 neutrinos per year from a multi-GeV stored muon-beam is seemingly the ideal tool for studying neutrino oscillations and CP-violations for leptons. The front-end of this facility plays a critical role in determining the number of muons that can be accepted by the downstream accelerators. Delivering peak performance requires transporting the muon beams through long sections of a beam channel containing high-gradient rf cavities and strong focusing solenoids. Here, we propose a novel scheme to improve the performance of the cavities, thereby increasing the number of muons within the acceptance of the accelerator chain. The key element of our new scheme is to apply a set of bucked coils along the lattice, thus forcing the external magnetic field to drop substantially within the cavity. We incorporate this idea into a new lattice design for a Neutrino Factory, and detail its performance numerically.

  6. Electrothermodynamic (etd) power converter

    SciTech Connect

    Marks, A.M.

    1983-07-26

    These inventions relate to novel advances in Electrothermodynamics (ETD), also known as charged aerosol, heat/electric power generators: (1) A new more efficient, compact converging/diverging configuration comprising a torus of revolution (TORON) used with a gas flywheel. (2) A ''Method II'' two-fluid mixed flow ejector/converter in a gas flywheel loop employing a primary steam or a high molecular weight driver jet such as a fluorocarbon containing charged aerosol water droplets and a low molecular weight carrier gas such as hydrogen or helium with an electro-negative gas additive, in a Rankine cycle including a vapor/gas and liquid separator with a bypass to the ejector/converter loop. (3) A ''Method III'' two-fluid mixed flow comprising a supersonic jet expanding conically within a subsonic flow, separated by a boundary layer in which the charged aerosol forms downstream of the orifice, at a cross section of at least 100 times the orifice section; and in which the electric charge density of the charged aerosol decreases along the jet axis, whereby substantially all of the kinetic power of the jet is converted to electric power within the jet, there being no ejector. (4) An array of supersonic jets utilizing Method III. (5) An array of supersonic jets utilizing Method III without separating duct walls in which ''convection cells'' provide return flows, forming a plurality of TORON configurations. (6) A supercritical Rankline cycle in a single stage employing Method III. (7) A method IV two-fluid cycle uses charged aerosols in an inert gas and operates on an Ericsson-type cycle. (8) Optimum operating conditions are defined for Methods II, III, and IV. (9) A high potential emitter is employed with a grounded body, and a sapphire tube sealed to metal by a new technique provides an insulating duct for the high temperature, high pressure vapor.

  7. 164 Currencies Converter

    NSDL National Science Digital Library

    Olsen and Associates of Zurich, Switzerland, a "developer of online forecasting technology for business and finance" has made this simple and fun service available. Simply enter the amount of currency for any of 164 currencies, the currency to be converted to, and the date of the exchange rate (back to January 1, 1990, in day/month/year format) into an online form, and presto, an exchange rate (which is then reversible) is obtained. As this is a demonstration product, neither multiple currencies nor multiple dates are allowed. Users should also read the FAQ to understand why the rate they get might be slightly different from the one their bank advertises.

  8. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will exceed this initial performance estimates. In advancing the Technology Readiness Level (TRL) of this type of wave energy converter from 3 to 4, we find the CycWEC to exceed our initial estimates in terms of hydrodynamic performance. Once fully developed and optimized, it has the potential to not just outperform all other WEC technologies, but to also deliver power at a lower LCOE than competing conventional renewables like wind and solar. Given the large wave power resource both domestically and internationally, this technology has the potential to lead to a large improvement in our ability to produce clean electricity at affordable cost.

  9. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-01-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  10. Gallium phosphide energy converters

    NASA Astrophysics Data System (ADS)

    Sims, P. E.; Dinetta, L. C.; Goetz, M. A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp -17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  11. Gallium phosphide energy converters

    SciTech Connect

    Sims, P.E.; Dinetta, L.C.; Goetz, M.A.

    1995-10-01

    Gallium phosphide (GaP) energy converters may be successfully deployed to provide new mission capabilities for spacecraft. Betavoltaic power supplies based on the conversion of tritium beta decay to electricity using GaP energy converters can supply long term low-level power with high reliability. High temperature solar cells, also based on GaP, can be used in inward-bound missions greatly reducing the need for thermal dissipation. Results are presented for GaP direct conversion devices powered by Ni-63 and compared to the conversion of light emitted by tritiarated phosphors. Leakage currents as low as 1.2 x 10(exp {minus}17) A/sq cm have been measured and the temperature dependence of the reverse saturation current is found to have ideal behavior. Temperature dependent IV, QE, R(sub sh), and V(sub oc) results are also presented. These data are used to predict the high-temperature solar cell and betacell performance of GaP devices and suggest appropriate applications for the deployment of this technology.

  12. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  13. Altitude and configuration of the potentiometric surface in Buckingham and Wrightstown townships, Bucks County, Pennsylvania, June 1992 through January 1993

    USGS Publications Warehouse

    McManus, B.C.; Schreffler, C.L.; Rowland, C.J.

    1994-01-01

    A map showing ground-water levels in Buckingham and Wrightstown Townships, Bucks County, Pennsylvania, was constructed from water levels measured in 251 wells and from 3 reported elevations of quarry sumps from June 1992 through January 1993. Observed water-level altitudes range from 459 feet above sea level along Burnt House Hill Road, south- west of Mechanicsville, to 10 feet above sea level along Swamp Road and Route 232, near Neshaminy Creek in Wrightstown Township.

  14. New considerations in the input filter design of a three-phase buck-type PWM rectifier for aircraft applications

    Microsoft Academic Search

    Marcelo Silva; Nico Hensgens; Jesus Oliver; Pedro Alou; Oscar Garcia; Jose A Cobos

    2011-01-01

    An EMI filter for a three-phase buck-type medium power pulse-width modulation rectifier is designed. This filter considers differential mode noise and complies with MIL-STD- 461E for the frequency range of 10kHz to 10MHz. In industrial applications, the frequency range of the standard starts at 150kHz and the designer typically uses a switching frequency of 28kHz because the fifth harmonic is

  15. Frequency response of resonant converters

    Microsoft Academic Search

    K. Siri; C. Q. Lee; S. J. Fang

    1990-01-01

    The general theory of the discrete small-signal analyses of resonant converters has been formulated in a closed form. For simplicity and verification, the state-plane diagram technique is used for the analysis. This theory is applicable to converters in half-bridge or full-bridge configurations when operated in the continuous conduction mode. Using a series resonant converter (SRC) as an example, the analytic

  16. Tunnel-diode converter analysis

    Microsoft Academic Search

    C. S. Kim

    1961-01-01

    An analysis of tunnel-diode converters is presented for two different conditions of operation. In the first, the converter is self-oscillating; in the second, the local oscillator (LO) voltage is provided from an external source. Two classes of self-oscillating converters are presented. The first operates on the fundamental of the oscillation frequency and the other operates on the second harmonic. Assuming

  17. Microfabricated multijunction thermal converters

    NASA Astrophysics Data System (ADS)

    Wunsch, Thomas Franzen

    2001-12-01

    In order to develop improved standards for the measurement of ac voltages and currents, a new thin-film fabrication technique for the multijunction thermal converter has been developed. The ability of a thermal converter to relate an rms ac voltage or current to a dc value is characterized by a quantity called `ac-dc difference' that is ideally zero. The best devices produced using the new techniques have ac-dc differences below 1 × 10-6 in the range of frequencies from 20 Hz to 10 kHz and below 7.5 × 10-6 in the range of frequencies from 20 kHz to 300 kHz. This is a reduction of two orders of magnitude in the lower frequency range and one order of magnitude in the higher frequency range over devices produced at the National Institute of Standards and Technology in 1996. The performance achieved is competitive with the best techniques in the world for ac measurements and additional evaluation is therefore warranted to determine the suitability of the devices for use as national standards that form the legal basis for traceable rms voltage measurements of time varying waveforms in the United States. The construction of the new devices is based on thin-film fabrication of a heated wire supported by a thermally isolated thin-film membrane. The membrane is produced utilizing a reactive ion plasma etch. A photoresist lift- off technique is used to pattern the metal thin-film layers that form the heater and the multijunction thermocouple circuit. The etching and lift-off allow the device to be produced without wet chemical etches that are time consuming and impede the investigation of structures with differing materials. These techniques result in an approach to fabrication that is simple, inexpensive, and free from the manual construction techniques used in the fabrication of conventional single and multijunction thermoelements. Thermal, thermoelectric, and electrical models have been developed to facilitate designs that reduce the low- frequency error. At high frequencies, from 300 kHz to 1 MHz, the performance of the device is degraded by a capacitive coupling effect that produces an ac-dc difference of approximately -90 × 10-6 at 1 MHz. A model is developed that explains this behavior. The model shows that an improvement in performance in the high-frequency range is possible through the use of very high or very low resistivity silicon substrates.

  18. Buck-Boost Inverters with Symmetrical Passive Four-terminal Networks

    Microsoft Academic Search

    Ryszard Strzelecki; M. Adamowicz; D. Wojciechowski

    2007-01-01

    Alternating voltage inverters (converters) supplied by low-voltage sources DC (ex. fuel cell, photovoltaic cell) are most frequently realized on the basis of the three fundamental topologies: a) PWM voltage inverter with non-transformer converter DC\\/DC in the \\

  19. Indian Converts Collection

    NSDL National Science Digital Library

    First published in 1727, the remarkable book "Indian Converts, or Some account of the lives and dying speeches of a considerable number of the Christianized Indians of Martha's Vineyard" is now available in full online. Written by Experience Mayhew, the book provides remarkable insights into the lives and culture of four generations of Native Americans in colonial America. This digitized version was created at Reed College, and visitors can look through all four sections of the work, which include "Indian Ministers" and "Pious Children." Throughout the work, Mayhew details the books that different age groups were reading, provides insights into early New England pedagogy and childrearing practices, and also describes each individual in terms of their own genealogy and personal history. The truly fantastic thing about the site is that it also contains an archive with over 600 images and documents that further contextualize the work. Also, the site contains study guides designed for classroom use that cover artifact analysis, genealogy, and reading gravestones.

  20. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    Device converts wave energy into electric power through array of insulated absorber elements responsive to field of impinging electromagnetic radiation. Device could also serve as solar energy converter that is potentially less expensive and fragile than solar cells, yet substantially more efficient.

  1. PWM Converter Power Density Barriers

    Microsoft Academic Search

    J. W. Kolar; U. Drofenik; J. Biela; M. L. Heldwein; H. Ertl; T. Friedli; S. D. Round

    2007-01-01

    Power density of power electronic converters in different applications has roughly doubled every 10 years since 1970. Behind this trajectory was the continuous advancement of power semiconductor device technology allowing an increase of converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts, and passive components and wire bond interconnection technologies could be major barriers for

  2. Matrix converters: a technology review

    Microsoft Academic Search

    Patrick W. Wheeler; José Rodríguez; Jon C. Clare; Lee Empringham; Alejandro Weinstein

    2002-01-01

    The matrix converter is an array of controlled semiconductor switches that connects directly the three-phase source to the three-phase load. This converter has several attractive features that have been investigated in the last two decades. In the last few years, an increase in research work has been observed, bringing this topology closer to the industrial application. This paper presents the

  3. Function: Cliplus:-`convert/dwedge_to_wedge`, Cliplus:-`convert/dwedge_to_wedge` -converting between wedge and dotted wedge

    E-print Network

    Ablamowicz, Rafal

    Function: Cliplus:-`convert/dwedge_to_wedge`, Cliplus:-`convert/dwedge_to_wedge` - converting between wedge and dotted wedge Calling Sequence: c1 := convert(p1,wedge_to_dwedge,F) c2 := convert(p2 Grassmann wedge monomials) · F, FT - argument of type name, symbol, matrix, array, or `&*`(numeric,{name,symbol,matrix

  4. Numerical study of a bucked-coil system for muon transport and cooling

    SciTech Connect

    Stratakis, Diktys; Alekou, Androula; Neuffer, David; Pasternak, Jaroslaw; Rogers, Chris T. [Brookhaven National Laboratory, Department of Physics, Upton, NY 11973 (United States); Imperial College London, Blackett Laboratory, Prince Consort Rd, London, SW7 2BW (United Kingdom); Fermi National Acceleartor Laboratory, Batavia, IL 60510 (United States); Imperial College London, Blackett Laboratory, Prince Consort Rd, London, SW7 2BW (United Kingdom) and Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom); Rutherford Appleton Laboratory, Chilton, Didcot (United Kingdom)

    2012-12-21

    A Neutrino Factory, which can deliver an intense flux of {approx}10{sup 21} neutrinos per year from a multi-GeV stored muon-beam is seemingly the ideal tool for studying neutrino oscillations and CP-violations for leptons. The front-end of this facility plays a critical role in determining the number of muons that can be accepted by the downstream accelerators. Delivering peak performance requires transporting the muon beams through long sections of a beam channel containing high-gradient rf cavities and strong focusing solenoids. Here, we propose a novel scheme to improve the performance of the cavities, thereby increasing the number of muons within the acceptance of the accelerator chain. The key element of our new scheme is to apply a set of bucked coils along the lattice, thus forcing the external magnetic field to drop substantially within the cavity. We incorporate this idea into a new lattice design for a Neutrino Factory, and detail its performance numerically.

  5. High reliability DC/DC converter module for electronic boards equipped with FPGAs

    NASA Astrophysics Data System (ADS)

    Viganò, W.; Boccardi, A.; Zamantzas, C.

    2015-01-01

    The Beam Instrumentation Group at CERN is designing a new general-purpose VME carrier module utilising several PTH04T230W DC/DC converters. These off-the-shelf converters are built with unshielded inductors and need to be mounted on the printed circuit board as stand-alone components. Thus, reducing the global manageability and increasing the total cost of the carrier module. The new design aims to develop a module with better power dissipation, efficiency and reliability. In the future, it should be also possible to be directly integrated on the mainboard. For this reason, a Buck DC/DC converter has been implemented with the following main characteristics: input range from 3.0 V to 5.5 V; output range from 0.6 V to 3.3 V, settable by means of an external resistor; output current protection at 6 A; maximum output ripple ± 50 mVpp; switching frequency of 300KHz; short circuit protection; On/Off function; EMI reduction with frequency spread spectrum; soft-start function and thermal shutdown, in a 16 × 19 mm compact size. The selected buck controller is the TPS40303 integrated circuit and drives the CSD16321 power MOSFET, both from Texas Instruments. All selected components have been used at a minimum derating of 50% to reduce component stress and increase the reliability of this module. The selected inductors, i.e. Bourns SRP1055, are the main contributor for the high efficiency (95%), due to their very low equivalent series resistance. On the 4-layer PCB comprising all the components of this module, a snubber circuit, for further reduction of the output ripple due to the MOSFET ringing, can be mounted optionally. It is left as an option due to its effect on the total efficiency. The board layout has been optimized for maximum heat transfer and it can be used without active cooling. The board can maintain the maximum temperature on its surface, while at maximum current output, below 55°C at 25°C ambient temperature. An example of the electrical performance simulation, as well as the verification methodology and the test bench realised will be shown.

  6. CRIME BULLETIN INCIDENT: Catalytic Converter Thefts

    E-print Network

    Barrett, Jeffrey A.

    CRIME BULLETIN C R I M E INCIDENT: Catalytic Converter Thefts DATE/TIME: 2/20/2013-2/27/2013, Various Times CONTACT: UCIPD Corporal B. Green (949) 824-5223 Catalytic converter Catalytic converter converters were stolen from various locations on the UC Irvine campus. The catalytic converters came from

  7. High power density dc-to-dc converters for aerospace applications

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.

    1990-01-01

    Three dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. Of the three circuits, the single-phase and three-phase versions of the dual active bridge topology demonstrate minimal stresses, better utilization of the transformer, bidirectional, and buck-boost modes of operation. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. The power transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. Based on the single-phase dual active bridge topology, a 50 kW, 50 kHz converter operating at an input voltage of 200 Vdc and an output voltage of 1600 Vdc was fabricated. Characteristics of current-fed output make the dual active bridge topologies amenable to paralleling and hence extension to megawatt power levels. Projections to a 1 MW system operating from a 500 Vdc input, at an output voltage of 10 kVdc and a switching frequency of 50 kHz, using MOS-controlled thyristors, coaxially wound transformers operating at three times the present current density with cooling, and multilayer ceramic capacitors, suggests an overall power density of 0.075 to 0.08 kg/kW and an overall efficiency of 96 percent.

  8. Coherence convertibility for mixed states

    E-print Network

    Xiaofei Qi; Zhaofang Bai; Shuanping Du

    2015-05-27

    In this paper, by providing a class of coherence measures in finite dimensional systems, a sufficient and necessary condition for the existence of coherence transformations that convert one probability distribution of any pure states into another one is obtained.

  9. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    Device will convert wind, water, tidal or wave energy into electrical or mechanical energy. Is comprised of windmill-like paddles or blades synchronously geared to orient themselves to wind direction for optimum energy extraction.

  10. Radiation tolerant power converter controls

    NASA Astrophysics Data System (ADS)

    Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

    2012-11-01

    The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

  11. HIGH EFFICIENCY AUXILIARY POWER CONVERTERS

    Microsoft Academic Search

    Geoff Walker

    The auxiliary load DC-DC converters of the Sunshark solar car have never been examined. An analysis of the current design reveals it is complicated, and inefficient. Some simple measures to greatly improve the efficiency are present which will achieve an overall worthwhile power saving. Two switch-mode power supply DC-DC converter designs are presented. One is a constant current supply for

  12. AMTEC cells challenge energy converters

    Microsoft Academic Search

    Henry Oman

    1999-01-01

    Sodium-base alkali-metal-thermal-to-electric conversion (AMTEC) cells have been receiving attention. Recently they were selected for the next generation deep-space missions, which need a converter that makes electricity from radioisotope heat. The AMTEC cell, being an electrochemical converter of heat to electricity, has no moving parts and is not limited to Carnot-cycle efficiency. However, its heat source and sink have to be

  13. Altitude and configuration of the potentiometric surface, Casey Village, Warminster and Upper Southampton townships, Bucks County, Pennsylvania, August 3, 1995

    USGS Publications Warehouse

    Sloto, Ronald A.; Grazul, Kevin E.

    1995-01-01

    A map showing the potentiometric surface in Casey Village, Warminster and Upper Southampton Townships, Bucks County, was constructed from water levels measured on August 3, 1995. The potentiometric surface, measured in 17 wells screened between 18 and 64 feet below land surface, ranged from 321.99 to 344.80 feet above sea level. The potentiometric surface, measured in 12 wells screened between 48 and 108 feet below land surface, ranged from 321.95 to 337.50 feet above sea level.

  14. IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 43, NO. 6, NOVEMBER/DECEMBER 2007 1619 Interleaved Zero-Current-Transition Buck Converter

    E-print Network

    and a significant reduction of the losses associated with diode reverse recovery are accomplished through addition remain significant. With the newest generation of IGBTs, which have greatly reduced the turn-off times of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital

  15. Optimal control law design for cyclic switching systems based on the minimum principle and singular arcs. Application to a buck converter

    Microsoft Academic Search

    Diego Patino

    2010-01-01

    In this article, we present a method for computing an optimal state feedback control law for switched affine systems which do not have common equilibrium points. The hybrid solution is obtained from a general convex formulation for which the existence of the optimal solution is guaranteed. We show that the synthesis of the optimal trajectories yields a partition of the

  16. Hexagram converter for static VAR compensation

    Microsoft Academic Search

    Jun Wen; K. M. Smedley

    2008-01-01

    A new multilevel converter - Hexagram converter is proposed for static VAR compensation in high-voltage high- power applications. The new converter is composed of six three- phase two-level standard voltage source converter (VSC) modules interconnected through inductors. It has the advantages of modular structure leading to easy construction and maintenance, no voltage unbalance, low voltage stress, low dc energy storage,

  17. Stirling Converters For Solar Power

    NASA Technical Reports Server (NTRS)

    Shaltens, Richard K.; Schreiber, Jeffrey G.

    1993-01-01

    Two designs expected to meet long-term goals for performance and cost. Proposed for advanced systems to convert solar thermal power to electrical power. Each system, designed to operate with 11-m-diameter paraboloidal reflector, includes solar-energy receiver, liquid-metal heat-transport subsystem, free-piston Stirling engine, cooling subsystem, alternator or generator coupled directly or indirectly to commercial electric-power system, and control and power-conditioning circuitry. System converts approximately 75 kW of input solar thermal power falling on collector to about 25 kW of output electrical power.

  18. Multilevel converters for power system applications

    SciTech Connect

    Lai, J.S.; Stovall, J.P. [Oak Ridge National Lab., TN (United States); Peng, F.Z. [Univ. of Tennessee, Knoxville, TN (United States)]|[Oak Ridge National Lab., TN (United States)

    1995-09-01

    Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component matching. One of the major limitations of the multilevel converters is the voltage unbalance between different levels. To avoid voltage unbalance between different levels, several techniques have been proposed for different applications. Excluding magnetic-coupled converters, this paper introduces three multilevel voltage source converters: (1) diode-clamp, (2) flying-capacitors, and (3) cascaded inverters with separate dc sources. The operation principle, features, constraints, and potential applications of these converters will be discussed.

  19. Soft-switching techniques in PWM converters

    Microsoft Academic Search

    Guichao Hua; Fred C. Lee

    1995-01-01

    A number of soft-switching pulse-width-modulated (PWM) converter techniques have been proposed, aimed at combining the desirable features of both the conventional PWM and resonant converters while avoiding their respective limitations. In this paper, three classes of zero-voltage soft-switching (PWM) converters (namely the zero-voltage-switched (ZVS) quasi-square-wave converters, ZVS-PWM converters, and zero-voltage-transition PWM converters) and two classes of zero-current soft-switching PWM converters

  20. New Tech High Schools: Results of the National Survey of Project Based Learning and High School Reform conducted by the Buck Institute for Education

    ERIC Educational Resources Information Center

    Ravitz, Jason

    2008-01-01

    In the fall of 2007, the Buck Institute for Education (BIE) conducted a national survey of high school reform and project based learning (PBL). The study included teachers from several major high school reform networks that emphasize PBL as an instructional approach: New Tech High, High Tech High, Edvision Schools, and Envision Schools. It also…

  1. WireGL: A Scalable Graphics System for Clusters Greg Humphreys Matthew Eldridge Ian Buck Gordon Stoll Matthew Everett Pat Hanrahan

    E-print Network

    Stanford University

    : I.3.2 [Computer Graphics]: Graphics Systems-- Distributed/network graphics; I.3.4 [Computer GraphicsWireGL: A Scalable Graphics System for Clusters Greg Humphreys£ Matthew Eldridge£ Ian Buck£ GordonGL API to each node in a cluster, virtualizing multiple graphics accel- erators into a sort

  2. Microscopic and flow cytometric semen assessment of Dutch AI-bucks: Effect of semen processing procedures and their correlation to fertility

    Microsoft Academic Search

    K. Peterson; M. A. P. M. Kappen; P. J. F. Ursem; J. O. Nöthling; B. Colenbrander; B. M. Gadella

    2007-01-01

    This study was done to determine the effects of processing techniques on the quality of semen from Dutch AI-bucks with the view on improving pregnancy rates after artificial insemination (AI) with liquid or frozen–thawed semen. Motility of spermatozoa was estimated under a microscope whereas the percentage live spermatozoa and the percentage live spermatozoa with intact acrosomes were determined by means

  3. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

    Walker, G. H.; Heinbockel, J. H.

    1987-01-01

    Photovoltaic converters are of interest for converting laser power to electrical power in a space-based laser power system. This paper describes a model for photovoltaic laser converters and the application of this model to a neodymium laser silicon photovoltaic converter system. A parametric study which defines the sensitivity of the photovoltaic parameters is described. An optimized silicon photovoltaic converter has an efficiency greater than 50 percent for 1000 W/sq cm of neodymium laser radiation.

  4. Mont Albert to Buck Mountain: Provenance of Appalachian Ophiolite Chromites Using Osmium Isotopes

    NASA Astrophysics Data System (ADS)

    Minarik, W. G.; Gale, A.; Booker, C.

    2003-12-01

    Osmium 187Os/188Os isotopic ratios have been determined for chrome-rich spinels from a suite of Appalachian ophiolites thought to represent Iapetus margin mantle formed and emplaced during the Ordovician. Because Re is incompatible during mantle melting while Os is compatible, non-radiogenic initial 187Os/188Os can constrain the average source and the timing of melt extraction, especially as Os is concentrated in chromite. Radiogenic ratios indicate contamination from aged sources with high Re/Os, such as mafic or continental crust. In rocks where spinel is the only remaining primary mineral, these properties can constrain the tectonic environment of formation as well as active-margin Os transport. There is little correction for 187Os in-growth since the Ordovician due to very low sample Re. Each ultramafic unit (from Mont Albert on the Gaspé Peninsula of Québec down to the Blue Ridge of North Carolina) forms a unique cluster of 187Os/188Os ratios, spanning 1 to 3%, but the whole range is about 10%. This corresponds to a range of initial ? Os of -1 to +9, where ? Os is the percent deviation from a chondritic source at the age of formation (roughly 500 Ma). Within ophiolites where detailed mapping and other geochemical information are available, there is a correlation between mantle-like Os and tholeiitic basalts; radiogenic Os and boninites (Thetford Mines). Continental arc-related mantle chromites (Baltimore Mafic Complex; ? Os +4 to +7) are the most radiogenic. The least radiogenic are chromites from the Staten Island serpentinite and Mont Albert (? Os -1 and 0, respectively), either indicating formation from a previously depleted source or that they predate the other Taconic ophiolites. The restricted range of each ophiolite, compared to the whole of the data set, allow provenance links to be made between isolated bodies. For example, the Buck Creek, NC ultramafic complex, which has undergone granulite facies metamorphism, (Tenthorey et al., 1996) has a similar 187Os/188Os to other Ordovician NC Blue Ridge dunites (? Os = +6.5 to +8.5), but distinctly different from a NC Piedmont chromitite (? Os = +2, Falls Lake mélange, Stoddard et al, 1989) that is inferred to be Neoproterozoic in age.

  5. A quick convertible agitating system

    Microsoft Academic Search

    Liu Ying; Song Biao; Ni Xiao-yu; Li Jia; Wang Li-jie; Fei Ye-qi; Wang Chang-qin

    2010-01-01

    Experiments of agitator properties are required a lot in process industry. A more efficient, practical and lower cost experimental system is demanded. In this research, a new type of quick convertible agitating system was designed which had a unique structure combined turning bracket with available impeller to enhance the prosperities and efficiency of the agitator experiment. Consisted of one driven

  6. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  7. Power converters for parabolic dishes

    Microsoft Academic Search

    V. C. Truscello; A. N. Williams

    1981-01-01

    The development status of receivers and power conversion units to be used with parabolic dish concentrators is presented. Applications are identified, and the key role played by the power converter element of the collector module is emphasized. The electrical output of the 11-meter-diameter dish modules which are being developed varies up to a maximum of about 25 kilowatts, depending on

  8. CONVERTING ABANDONED LANDS TO CROPLAND

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because of economic conditions, areas of cropland in Ukraine have been left unused for several years. These abandoned lands are now infested with perennial weeds. Producers are interested in converting these lands back to cropland with no-till systems to preserve soil benefits gained by not tillin...

  9. Efficiency and Reliability Improvement in Wind Turbine Converters by Grid Converter Adaptive Control

    E-print Network

    Munk-Nielsen, Stig

    Efficiency and Reliability Improvement in Wind Turbine Converters by Grid Converter Adaptive test setup. Keywords >, >, >, >>. Abstract This paper presents a control method that reduces the losses in wind turbine converters adaptively

  10. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler,; Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2010-10-26

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  11. Portable convertible blast effects shield

    DOEpatents

    Pastrnak, John W. (Livermore, CA); Hollaway, Rocky (Modesto, CA); Henning, Carl D. (Livermore, CA); Deteresa, Steve (Livermore, CA); Grundler, Walter (Hayward, CA); Hagler, Lisle B. (Berkeley, CA); Kokko, Edwin (Dublin, CA); Switzer, Vernon A (Livermore, CA)

    2007-05-22

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more telescoping cylindrical rings operably connected to each other to convert between a telescopically-collapsed configuration for storage and transport, and a telescopically-extended upright configuration forming an expanded inner volume. In a first embodiment, the upright configuration provides blast effects shielding, such as against blast pressures, shrapnel, and/or fire balls. And in a second embodiment, the upright configuration provides ballistic shielding, such as against incoming weapons fire, shrapnel, etc. Each ring has a high-strength material construction, such as a composite fiber and matrix material, capable of substantially inhibiting blast effects and impinging projectiles from passing through the shield. And the set of rings are releasably securable to each other in the telescopically-extended upright configuration, such as by click locks.

  12. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, D. P.; Oettinger, P. E.

    1976-01-01

    The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

  13. Cell modulated DC/DC converter

    E-print Network

    Warren, James Raymond, III

    2005-01-01

    A very high frequency converter roughly based on a class E topology is investigated for replacing a conventional boost converter circuit. The loss mechanisms in class E inverters are characterized, and metrics are developed ...

  14. Novel zero-voltage-transition PWM converters

    Microsoft Academic Search

    Guichao Hua; Ching-Shan Leu; Fred C. Lee

    1992-01-01

    A class of zero voltage transition (ZVT) power converters is proposed in which both the transistor and the rectifier operate with zero voltage switching and are subjected to minimum voltage and current stresses. The boost ZVT-PWM converter is used as an example to illustrate the operation of these converters. A 300 kHz, 600 W ZVT-PWM boost, DC-DC converter, and a

  15. Integrated converters for switched reluctance motor drives

    Microsoft Academic Search

    Z. Nie; A. Emadi

    2004-01-01

    Switched reluctance motors (SRM) are relatively inexpensive and robust. The proportional cost of the power electronics is large especially for lower power drives. It is therefore important to optimize the power converter for the practical applications. This work presents the concept of integrated converters for SRM drives. Basic converters based on the sub-integrated concept are also discussed for the purpose

  16. Light-off behavior of catalytic converters

    Microsoft Academic Search

    P. S. Hagan; D. W. Schwendeman

    1994-01-01

    This paper studies a system of partial differential equations modeling the behavior of an automotive catalytic converter. The particular phenomenon considered in detail is light-off, when the temperature of the converter changes dramatically from cold to hot somewhere within the converter. The initial position of light-off and the subsequent movement of this steep jump in temperature toward the inlet of

  17. COMMUNITY ALERT INCIDENT: Catalytic Converter Thefts

    E-print Network

    Rose, Michael R.

    COMMUNITY ALERT C R I M E INCIDENT: Catalytic Converter Thefts DETAILS: There has been a recent series of catalytic converter thefts from vehicles in parking lots adjacent to campus housing communities. The suspect(s) typically go underneath the victim's vehicle to steal the catalytic converter. A catalytic

  18. Digital scan converters in diagnostic ultrasound imaging

    Microsoft Academic Search

    JONATHAN OPHIR; N. F. Maklad

    1979-01-01

    The use of digital scan converters in ultrasonic imaging is presented. The basic principles of ultrasound physics and imaging are briefly reviewed. A detailed description of the components and principles of operation of digital scan converters follows. The capabilities of current digital scan converters in terms of resolution, writing speed, pre-processing and postprocessing, and new rapid scanning techniques are discussed.

  19. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z. (Knoxville, TN)

    2000-01-01

    An auxiliary resonant dc tank (ARDCT) converter is provided for achieving soft-switching in a power converter. An ARDCT circuit is coupled directly across a dc bus to the inverter to generate a resonant dc bus voltage, including upper and lower resonant capacitors connected in series as a resonant leg, first and second dc tank capacitors connected in series as a tank leg, and an auxiliary resonant circuit comprising a series combination of a resonant inductor and a pair of auxiliary switching devices. The ARDCT circuit further includes first clamping means for holding the resonant dc bus voltage to the dc tank voltage of the tank leg, and second clamping means for clamping the resonant dc bus voltage to zero during a resonant period. The ARDCT circuit resonantly brings the dc bus voltage to zero in order to provide a zero-voltage switching opportunity for the inverter, then quickly rebounds the dc bus voltage back to the dc tank voltage after the inverter changes state. The auxiliary switching devices are turned on and off under zero-current conditions. The ARDCT circuit only absorbs ripples of the inverter dc bus current, thus having less current stress. In addition, since the ARDCT circuit is coupled in parallel with the dc power supply and the inverter for merely assisting soft-switching of the inverter without participating in real dc power transmission and power conversion, malfunction and failure of the tank circuit will not affect the functional operation of the inverter; thus a highly reliable converter system is expected.

  20. Converting Petroleum Coke to Electricity

    E-print Network

    Pavone, A.

    as compared to soft coal, has also created flame stability problems for both initial ignition, and sustained ignition. Lastly, ash deposition in the form of slagging on heat transfer surface walls has sometimes been a problem in utility scale boilers... (250 psig) slagging gasifier that introduces both oxygen and steam. The reaction is designed to convert coke to a synthesis gas mixture of CO and H2. Sulfur in the form of H2S is removed ESL-IE-92-04-47 Proceedings from the 14th National Industrial...

  1. The myosin converter domain modulates muscle performance.

    PubMed

    Swank, Douglas M; Knowles, Aileen F; Suggs, Jennifer A; Sarsoza, Floyd; Lee, Annie; Maughan, David W; Bernstein, Sanford I

    2002-04-01

    Myosin is the molecular motor that powers muscle contraction as a result of conformational changes during its mechanochemical cycle. We demonstrate that the converter, a compact structural domain that differs in sequence between Drosophila melanogaster myosin isoforms, dramatically influences the kinetic properties of myosin and muscle fibres. Transgenic replacement of the converter in the fast indirect flight muscle with the converter from an embryonic muscle slowed muscle kinetics, forcing a compensatory reduction in wing beat frequency to sustain flight. Conversely, replacing the embryonic converter with the flight muscle converter sped up muscle kinetics and increased maximum power twofold, compared to flight muscles expressing the embryonic myosin isoform. The substitutions also dramatically influenced in vitro actin sliding velocity, suggesting that the converter modulates a rate-limiting step preceding cross-bridge detachment. Our integrative analysis demonstrates that isoform-specific differences in the myosin converter allow different muscle types to meet their specific locomotion demands. PMID:11901423

  2. An Integrated Speed and Accuracy-Enhanced CMOS Current Sensor With Dynamically Biased Shunt Feedback for Current-Mode Buck Regulators

    Microsoft Academic Search

    Mengmeng Du; Hoi Lee

    2010-01-01

    This paper presents a new compact on-chip current-sensing circuit to enable current-mode buck regulators operating at a high switching frequency for reducing the inductor profile. A dynamically biased shunt feedback technique is developed in the proposed current sensor to push nondominant poles to higher frequencies, thereby improving the speed and stability of the current sensor under a wide range of

  3. Fuzzy PID Controller Design for PWM-Buck EBW Stabilized High-Voltage Source Using Saber-Matlab Co-simulation

    Microsoft Academic Search

    Jinhai Mol; Shaojia He; Yunping Zou

    2007-01-01

    A novel PWM-buck type EBW (electron beam welder) stabilized high-voltage source circuit system is introduced, in which an inductance current-limiting circuit is attached to prevent surge and over current thus increasing the system's working reliability and stability. Due to its strong non-linearity and large signal working condition, it is difficult to reach a relatively satisfactory performance with a conventional PID

  4. Differential Mode Input Filter Design for a Three-Phase Buck-Type PWM Rectifier Based on Modeling of the EMC Test Receiver

    Microsoft Academic Search

    Thomas Nussbaumer; Marcelo Lobo Heldwein; Johann W. Kolar

    2006-01-01

    For a three-phase buck-type pulsewidth modulation rectifier input stage of a high-power telecommunications power supply module, a differential-mode (DM) electromagnetic compatibility (EMC) filter is designed for compliance to CISPR 22 Class B in the frequency range of 150 kHz-30 MHz. The design is based on a harmonic analysis of the rectifier input current and a mathematical model of the measurement

  5. Residence time, chemical and isotopic analysis of nitrate in the groundwater and surface water of a small agricultural watershed in the Coastal Plain, Bucks Branch, Sussex County, Delaware

    USGS Publications Warehouse

    Clune, John W.; Denver, Judith M.

    2012-01-01

    Nitrate is a common contaminant in groundwater and surface water throughout the Nation, and water-resource managers need more detailed small-scale watershed research to guide conservation efforts aimed at improving water quality. Concentrations of nitrate in Bucks Branch are among the highest in the state of Delaware and a scientific investigation was performed to provide water-quality information to assist with the management of agriculture and water resources. A combination of major-ion chemistry, nitrogen isotopic composition and age-dating techniques was used to estimate the residence time and provide a chemical and isotopic analysis of nitrate in the groundwater in the surficial aquifer of the Bucks Branch watershed in Sussex County, Delaware. The land use was more than 90 percent agricultural and most nitrogen inputs were from manure and fertilizer. The apparent median age of sampled groundwater is 18 years and the estimated residence time of groundwater contributing to the streamflow for the entire Bucks Branch watershed at the outlet is approximately 19 years. Concentrations of nitrate exceeded the U.S. Environmental Protection Agency drinking-water standard of 10 milligrams per liter (as nitrogen) in 60 percent of groundwater samples and 42 percent of surface-water samples. The overall geochemistry in the Bucks Branch watershed indicates that agriculture is the predominant source of nitrate contamination and the observed patterns in major-ion chemistry are similar to those observed in other studies on the Mid-Atlantic Coastal Plain. The pattern of enrichment in nitrogen and oxygen isotopes (?15N and ?18O) of nitrate in groundwater and surface water indicates there is some loss of nitrate through denitrification, but this process is not sufficient to remove all of the nitrate from groundwater discharging to streams, and concentrations of nitrate in streams remain elevated.

  6. A dc to dc converter

    NASA Technical Reports Server (NTRS)

    Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H. (inventors)

    1984-01-01

    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

  7. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    A support is provided for use in a therminonic converter to support an end of an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially as its temperature changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housing, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  8. Thermionic converter emitter support arrangement

    DOEpatents

    Allen, Daniel T. (La Jolla, CA)

    1990-01-01

    A support is provided for use in a thermionic converter to support an end an emitter to keep it out of contact with a surrounding collector while allowing the emitter end to move axially at its temperatures changes. The emitter end (34) is supported by a spring structure (44) that includes a pair of Belleville springs, and the spring structure is supported by a support structure (42) fixed to the housing that includes the collector. The support structure is in the form of a sandwich with a small metal spring-engaging element (74) at the front end, a larger metal main support (76) at the rear end that is attached to the housng, and with a ceramic layer (80) between them that is bonded by hot isostatic pressing to the metal element and metal main support. The spring structure can include a loose wafer (120) captured between the Belleville springs.

  9. Combining Long-Term Watershed Monitoring at Buck Creek with Spatially Extensive Ecosystem Data to Understand the Processes of Acid Rain Effects and Recovery

    NASA Astrophysics Data System (ADS)

    Lawrence, G. B.; Ross, D. S.; Sullivan, T. J.; McDonnell, T. C.; Bailey, S. W.; Dukett, J. E.

    2014-12-01

    The Buck Creek Monitoring Watershed, in the western Adirondack Region of New York, has provided long-term data back to 1982 for tracking acid rain effects and recovery, and for supporting fundamental research on environmental change. At Buck Creek, monitoring acidic deposition effects as they worsened, then diminished, has advanced our understanding of key biogeochemical processes such as Al mobilization. Although Al mobilization has been one of the primary adverse effects of acidic deposition, in the recovery phase it is now affecting terrestrial and aquatic ecosystems in new ways that could be both positive and negative, as soils and surface waters respond to further declines in acidic deposition. Using stream Al measurements from Buck Creek over varying seasons and flows, a new index, the base cation surplus (BCS), was developed to account for dissolved organic carbon (DOC) effects on the relationship between ANC and inorganic Al. Mobilization of inorganic Al, the form toxic to biota, occurs below a BCS of zero, regardless of DOC concentrations. Soil and stream data from Adirondack surveys showed that a BCS value of zero corresponds to a soil base saturation value in the B horizon of approximately 12%. Additional Adirondack survey work indicated that, where sugar maple stands grew in soils with base saturation values below 12%, seedling regeneration was nearly zero, suggesting a link between Al mobilization and impairment of tree regeneration. In recovering Adirondack lakes, the BCS was also used to show that increasing trends in DOC were accelerating decreases of inorganic Al beyond what would be expected from the increasing trends of ANC. Similar decreases of inorganic Al in Buck Creek, were coupled with increases in organic Al concentrations, which resulted in no trend in total Al concentrations despite a strong increase in pH. Sampling of Buck Creek soils in 1997, and again in 2009-2010, indicated a substantial decrease in forest floor exchangeable Al, of which approximately 85% was accounted for by stream export through leaching of exchangeable Al from soil to stream. Changes in the chemistry of the upper B horizon also suggest the possibility that recovery from acidification is accelerating podzolization in these soils.

  10. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Elbuluk, Malik E.; Gerber, Scott; Hammoud, Ahmad; Patterson, Richard L.

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  11. Converted-wave seismology for coal exploration

    Microsoft Academic Search

    Natasha Hendrick

    Despite the success of multi-component seismology and asso- ciated converted-wave (PS-wave) imaging methods in the petroleum industry, there has been relatively little effort devoted to shallow, high-resolution converted-wave imaging in the coal sector. By analogy to petroleum-scale applications, converted-wave seismic imaging in the coal environment offers interesting possibilities for independent validation of mapped stru c t u res, clearer imaging

  12. Novel zero-current-transition PWM converters

    Microsoft Academic Search

    Guichao Hua; Eric X. Yang; Yimin Jiang; Fred C. Lee

    1993-01-01

    A new family of zero-current-transition (ZCT) pulse-width-modulated (PWM) converters are proposed. The new family of converters implements zero-current turn-off for power transistor(s) without increasing voltage\\/current stresses and operates at a fixed frequency. The proposed converters are deemed most suitable for high-power applications where the minority-carrier semiconductor devices (such as IGBTs, BJTs, and MCTs) are predominantly used as the power switches.

  13. Novel zero-current-transition PWM converters

    Microsoft Academic Search

    Guichao Hua; Eric X. Yang; Yimin Jiang; Fred C. Lee

    1994-01-01

    A new family of zero-current-transition (ZCT) pulsewidth-modulated (PWM) converters is proposed. The new family of converters implements zero-current turn-off for power transistor(s) without increasing voltage\\/current stresses and operates at a fixed frequency. The proposed converters are deemed most suitable for high-power applications where the minority-carrier semiconductor devices (such as IGBTs, BJTs, and MCTs) are predominantly used as the power switches.

  14. Inverting ZCS Switched-Capacitor Bidirectional Converter

    Microsoft Academic Search

    Yaung-Shung Lee; Yin-Yuan Chiu; Ming-Wang Cheng

    2006-01-01

    The proposed inverting type zero-current switching switched-capacitor (ZCS SC) DC\\/DC converters are a new type of bi-directional power flow control conversion schemes. They possess high efficiency, low EMI emission and current stress features for the proposed quasi-resonant switched-capacitor inverting converters. A family of inverting type zero-current switching switched-capacitor bi-directional converters is presented, which can improve the current stress problem during

  15. A Novel Lossless Snubber for Boost Converters

    Microsoft Academic Search

    J. Marshall; M. Kazerani

    2006-01-01

    Advanced transportation technologies, such as hybrid-electric vehicles, battery-electric vehicles, and fuel cell vehicles, rely on high-power DC\\/DC converters to interconnect and manage their power systems. Boost converters are especially useful in stepping-up the voltage from a battery or fuel cell to match the electric motor voltage range. However, conventional high-power boost converters are very large and heavy, partly due to

  16. A theoretical study of photovoltaic converters

    NASA Technical Reports Server (NTRS)

    Heinbockel, John H.

    1987-01-01

    Mathematical models for the photovoltaic conversion of laser power were developed. These models simulate the operation of planar and vertical junction photovoltaic converters and are described in detail.

  17. A variable parameter thermionic energy converter 

    E-print Network

    Bragg, Bobby Joe

    1967-01-01

    . In describing the electron energy gain and loss pro- cesses in the interelectrode region, he notes that, at a particular point in the interelectrode plasma, the rates of energy gain and loss for the electron gas balance, and the electron kinetic energy flux... LIST OF FIGURES FIGURE 1. SIMPLE SCHEMATIC OF A THERMIONIC CONVERTER PAGE 2. POWER VS SPACING WITH A MINIMUM POWER POINT 3. POWER VS SPACING WITH NO MINIMUM POWER POINT 4. CONVERTER MOTIVE DIAGRAM~ O'E = 5. CONVERTER MOTIVE DIAGRAM~ 6. CONVERTER...

  18. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

    This report presents study results on hybrid DC/DC converter stability testing methods. An input impedance measurement method and a gain/phase margin measurement method were evaluated to be effective to determine front-end oscillation and feedback loop oscillation. In particular, certain channel power levels of converter input noises have been found to have high degree correlation with the gain/phase margins. It becomes a potential new method to evaluate stability levels of all type of DC/DC converters by utilizing the spectral analysis on converter input noises.

  19. Distributed interleaving of paralleled power converters

    E-print Network

    Kassakian, J.G.

    This paper introduces a distributed approach to interleaving paralleled power converter cells. Unlike conventional methods, the distributed approach requires no centralized control, automatically accommodates varying numbers ...

  20. Interpretation of Borehole Geophysical Logs at Area C, Former Naval Air Warfare Center, Warminster Township, Bucks County, Pennsylvania, 2007

    USGS Publications Warehouse

    Sloto, Ronald A.

    2008-01-01

    This study was done by the U.S. Geological Survey in cooperation with the U.S. Navy at Area C of the former Naval Air Warfare Center in Warminster Township, Bucks County, Pa., in support of hydrogeological investigations conducted by the Navy to address ground-water contamination in the Stockton Formation. Borehole geophysical logs were collected, heatpulse-flowmeter measurements were made, and borehole television surveys were run in seven boreholes ranging from 31 to 75 feet deep. Caliper logs and borehole television surveys were used to identify fractures and the location of possible water-bearing zones. Heatpulse-flowmeter measurements were used to identify fractures that were water-bearing zones. Natural-gamma and single-point-resistance logs were used to correlate lithology across the area. Elevated concentrations of tetrachloroethylene (PCE) were measured in water samples from wells with water-bearing zones in the interval of the aquifer where monitor well HN-23A is screened. Water samples from wells with water-bearing zones above or below this interval had substantially lower concentrations of PCE. Wells screened in this interval yielded less than 0.5 gallon per minute, indicating that the interval has low permeability; this may account for the small areal extent and slow migration of PCE.

  1. Synthesis of Multilevel Converters Based on Single-and\\/or Three-phase Converter Building Blocks

    Microsoft Academic Search

    Jun Wen; K. Smedley

    2007-01-01

    This paper synthesizes a family of multilevel converters that is constructed by using multiple well-developed single-phase converters and\\/or three-phase converters as the building blocks. The resulting advantages include modular structure that leads to convenient construction, maintenance and control as well as extension to higher voltage levels. One successful example from this family is the cascaded H-bridge converter, which is now

  2. A closely regulated TWT converter.

    NASA Technical Reports Server (NTRS)

    Hopper, D. J.; Andryczyk, R. W.

    1971-01-01

    The design concept for the TWT amplifier converter for possible use in the Thermoelectric Outer Planet Spacecraft (TOPS) is presented. An unusual combination of semiconductors and magnetics was utilized to achieve very stable voltage regulation on a number of separate outputs to satisfy the requirements of a high-power TWT, and at the same time operate at an efficiency of better than 90% from a 30-V source. The circuitry consists of an output filter, an auxiliary Jensen oscillator driving a high-reactance transformer to provide current limiting to the heater, a variable time delay, a main Jensen oscillator driving the power transformer with a maximum step-up ratio of 120 to 1, and series transistorized post regulators to provide precise voltage adjustment and low output impedance. This paper discusses the design of the high-reactance transformer and the high step-up ratio transformer, as well as the high-voltage series regulators that are limited in range and operate at the top of the unregulated output voltage. Test data are presented, and details of current transients caused by charging the filter circuits, input current ripple, and output voltage ripples are considered.

  3. RF digital-to-analog converter

    DOEpatents

    Conway, Patrick H. (Rancho Palos Verdes, CA); Yu, David U. L. (Rancho Palos Verdes, CA)

    1995-01-01

    A digital-to analogue converter for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration.

  4. Resonant converter transformer design and optimization

    Microsoft Academic Search

    Garet E. Gamache; Charles R. Sullivan

    2011-01-01

    A new, low-profile, low-loss resonant converter transformer is proposed. Its design allows the absorption of the series inductor of the resonant converter through its leakage inductance. The windings are concentric with ferrite between them to control the leakage inductance. This arrangement offers electromagnetic interference (EMI) reduction compared to sim- ilar designs. Design software which optimizes the transformer inclusive of all

  5. DC current sensor for PWM converters

    Microsoft Academic Search

    Arthur W. Kelley; John E. Titus

    1991-01-01

    A sensor for inductor current in PWM converters which offers improved performance over presently available sensors is presented. The sensor is based on a saturable transformer, derives power from existing converter waveforms, provides DC isolation, and has inherently wide bandwidth. The sensor is compared to available current sensors. A theory of operation for the sensor is presented, the results of

  6. Time interleaved counter analog to digital converters 

    E-print Network

    Danesh, Seyed Amir Ali

    2011-11-22

    The work explores extending time interleaving in A/D converters, by applying a high-level of parallelism to one of the slowest and simplest types of data-converters, the counter ADC. The motivation for the work is to ...

  7. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.

  8. Converter Design for a Model Solar Car

    Microsoft Academic Search

    Richard Duke; Simon Round

    To provide our students with practical experience in power electronic design they undertake an assignment that involves a model solar car race. The students are required to design, build and demonstrate a dc-dc converter that matches the output from a 10W solar panel to a permanent magnet DC motor. The converter must step down the output voltage from the panel

  9. GaN betavoltaic energy converters

    Microsoft Academic Search

    C. Honsberg; W. A. Doolittle; M. Allen; C. Wang

    2005-01-01

    Semiconductor betavoltaic converters use energy from radioisotope sources to generate electricity for remote applications requiring power for 5-50 years. To be competitive with thermoelectric devices, they must achieve an efficiency above 20%. This paper presents the design rules and efficiency calculations for such high efficiency GaN betavoltaic converters, and experimentally demonstrates the radiation tolerance of GaN.

  10. Laser energy converted into electric power

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1973-01-01

    Apparatus verifies concepts of converting laser energy directly into electric energy. Mirror, placed in beam and inclined at angle to it, directs small amount of incident radiation to monitor which establishes precise power levels and other beam characteristics. Second mirror and condensing lens direct bulk of laser energy into laser plasmadynamic converter.

  11. Quasi Linear DC\\/DC Converters

    Microsoft Academic Search

    Deepak M. Divan; Satish Rajagopalan

    2006-01-01

    Demanding high power applications, such as medical imaging, fast processors, and pulsed loads are requiring new levels of performance from dc\\/dc converters. Extremely low ripple voltages, blazing speed and response, all with high efficiency and small size are placing conflicting requirements on the dc\\/dc converter designer. Conventional design approaches are not able to meet the needs easily, and it is

  12. Equity financing and corporate convertible bond policy

    Microsoft Academic Search

    P. Jalan; G. Barone-Adesi

    1995-01-01

    A co-operative game playing model is used to examine ex ante the decision parameters which are involved in the selection of callable convertible bonds as a means of delayed equity financing. The differential tax treatment of coupon interest and dividend payments, coupled with market friction and incompleteness, provides sufficient reason for convertible debt issuance. Though there is a myopic incentive

  13. Fuel to Burn: Economics of Converting Forest

    E-print Network

    Fried, Jeremy S.

    Fuel to Burn: Economics of Converting Forest Thinnings to Energy Using BioMax in Southern Oregon E a small-scale (100-kW) BioMax without a subsidy or tax credit, even if fuel were delivered to the plant; Christensen, Glenn. 2005. Fuel to burn: Economics of converting forest thinnings to energy using Bio

  14. An auxiliary resonant soft switching matrix converter

    Microsoft Academic Search

    M. J. Bland; J. C. Clare; P. W. Wheeler; L. Empringham; M. Apap

    2004-01-01

    This paper is concerned with the design, construction and testing of a 3-phase to 3-phase soft switching matrix converter. Two auxiliary soft switching circuits are added to each output phase in order to achieve soft switching without significantly increasing the conduction losses. The converter operation is discussed with reference to theoretical waveforms. The distribution of the switching losses with respect

  15. Characteristics of CVD silicon carbide thermionic converters

    Microsoft Academic Search

    D. B. Goodale; P. Reagan; G. Miskolczy; D. Lieb; F. N. Huffman

    1981-01-01

    Development work has recently been undertaken on a thermionic converter for terrestrial applications which employs chemically vapor deposited (CVD) silicon carbide as a protective coating over the CVD tungsten emitter. A 1-in.-diam hemispherical converter with an active emitting area of 6 sq cm has been constructed and has undergone over 7200 hours of life testing at an emitter temperature of

  16. Converter concepts to increase the integration level

    Microsoft Academic Search

    Jelena Popovic; J. A. Ferreira

    2005-01-01

    In the previous work, a way to improve packaging of power electronic converters by increasing integration level and using multifunctional construction parts is presented. The quantities intended to evaluate integration level and volumetric utilization in power converters are introduced. Based on these values, a number of methods to increase the integration level are presented. A design process in the form

  17. A direct control method for matrix converters

    Microsoft Academic Search

    Peter Mutschler; Matthias Marcks

    2002-01-01

    Until now, direct control methods have been mainly investigated and used in conjunction with voltage source converters. In this paper, the authors develop a direct current control method for matrix converters. There are two objectives for the direct current control: the desired current has to be impressed into the load, and the current, drawn from the mains, should be in

  18. A zero switching loss matrix converter

    Microsoft Academic Search

    Ching-Tsai Pan; Tsung-Cheng Chen; Jenn-Jong Shieh

    1993-01-01

    A low loss bidirectional switch set is proposed for a matrix power converter. The proposed switch is able to turn on at zero current and turn off at zero voltage to achieve almost zero loss and soft switching. Hence, a simple hysteretic current control can now be applied directly to a matrix power converter without adding any additional snubber circuit

  19. New control strategy for matrix converter

    Microsoft Academic Search

    Jun Oyama; Tsuyoshi Higuchi; Eiji Yamada; Takashi Koga; Thomas Lipo

    1989-01-01

    The authors propose a control strategy for the matrix converter which allows output voltage of 0.866 times the supply voltage to be generated. They discuss how to eliminate voltage and current spikes in the commutation. The system operation is examined and confirmed by experiments using a matrix converter with anti-parallel-connected SITs (static induction thyristors)

  20. A novel power converter for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Yuvarajan, S.; Yu, Dachuan; Xu, Shanguang

    A simple and economical power conditioner to convert the power available from solar panels into 60 Hz ac voltage is described. The raw dc voltage from the solar panels is converted to a regulated dc voltage using a boost converter and a large capacitor and the dc output is then converted to 60 Hz ac using a bridge inverter. The ratio between the load current and the short-circuit current of a PV panel at maximum power point is nearly constant for different insolation (light) levels and this property is utilized in designing a simple maximum power point tracking (MPPT) controller. The controller includes a novel arrangement for sensing the short-circuit current without disturbing the operation of the PV panel and implementing MPPT. The switching losses in the inverter are reduced by using snubbers. The results obtained on an experimental converter are presented.

  1. Generation, Classification and Analysis of Switched-Mode DC-to-DC Converters by the Use of Converter Cells

    Microsoft Academic Search

    Richard Tymerski; Vatche Vorperian

    1986-01-01

    A method is presented which combines generation, classification and analysis of DC-to-DC PWM converters. Fundamental blocks known as converter cells can be used to generate a plethora of converters leading to a number of useful new converter topologies. A classification of basic converters is proposed in terms of converter-cell generated families. The converter cells considered may be seen as three-terminal

  2. Characteristics of CVD silicon carbide thermionic converters

    NASA Astrophysics Data System (ADS)

    Goodale, D. B.; Reagan, P.; Miskolczy, G.; Lieb, D.; Huffman, F. N.

    Development work has recently been undertaken on a thermionic converter for terrestrial applications which employs chemically vapor deposited (CVD) silicon carbide as a protective coating over the CVD tungsten emitter. A 1-in.-diam hemispherical converter with an active emitting area of 6 sq cm has been constructed and has undergone over 7200 hours of life testing at an emitter temperature of 1730 K, collector temperature between 800 and 900 K and power output of 2 W/sq cm at 0.25 V. A module using four 1-in. hemispherical converters was built to investigate the problems of operating converter arrays, revealing the importance of minimizing interconnecting lead loss. A 2-in.-diam prototype converter was constructed which has so far accumulated over 1700 hours of life tests at emitter temperatures of 1600 to 1700 K in a natural gas fired furnace. As a result of problems with emitter-collector spacing and temperature nonuniformities discovered during testing, a new converter is being designed with a torispherical hot shell-emitter configuration. Composite hot shell-emitter structures have successfully undergone a series of severe thermal and mechanical tests under conditions exceeding any the shell would experience in application. Results indicate that combustion-heated thermionic converters can operate stably at high temperatures for long periods at interesting efficiencies and power densities.

  3. A review of "Women, Property, and the Letters of the Law in Early Modern England." by Nancy E. Wright Margaret Ferguson A. R. Buck eds. 

    E-print Network

    Nancy M. Bunker

    2005-01-01

    overlooked?ways. Nancy E. Wright, Margaret Ferguson, A. R. Buck, eds. Women, Property, and the Letters of the Law in Early Modern England. Toronto: University of Toronto Press, 2004. ix +304 pp. $65.00. Review by NANCY M. BUNKER, MACON STATE COLLEGE.... Women, Property, and the Letters of the Law in Early Modern England, an inter- disciplinary examination of women?s legal status and property relationships, directs attention away from the ?well-known narrative about women?s legal disabilities...

  4. Matrix laser IR-visible image converter

    SciTech Connect

    Lipatov, N I; Biryukov, A S [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2006-04-30

    A new type of a focal matrix IR-visible image converter is proposed. The pixel IR detectors of the matrix are tunable microcavities of VCSEL (vertical-cavity surface emitting laser) semiconductor microstructures. The image conversion is performed due to the displacements of highly reflecting cavity mirrors caused by thermoelastic stresses in their microsuspensions appearing upon absorption of IR radiation. Analysis of the possibilities of the converter shows that its sensitivity is 10{sup -3}-10{sup -2} K and the time response is 10{sup -4}-10{sup -3} s. These characteristics determine the practical application of the converter. (laser applications and other topics in quantum electronics)

  5. 31 CFR 363.164 - Is a converted savings bond eligible to be converted back into a definitive bond?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...converted savings bond eligible to be converted back into a definitive bond? 363.164 ...converted savings bond eligible to be converted back into a definitive bond? Once a definitive...book-entry bond, it may not be converted back into a definitive...

  6. Rotorcraft convertible engines for the 1980s

    NASA Technical Reports Server (NTRS)

    Eisenberg, J. D.

    1982-01-01

    Two rotorcraft studies were executed. The goal was to identify attractive techniques for implementing convertible powerplants for the ABC, Folded Tilt Rotor, and X-wing type high speed, high-L/D rotorcraft; to determine the DOC and fuel savings benefits achieved thereby; and to define research required to bring these powerplants into existence by the 1990's. These studies are reviewed herein and the different methods of approach are pointed out as well as the key findings. Fan shaft engines using variable inlet guide vanes or torque converters, and turboprop powerplants appear attractive. Savings in DOC and fuel consumption of over 15 percent are predicted in some cases as a result of convertible engine use rather than using separate engines for the thrust and the shaft functions. Areas of required research are fan performance (including noise), integrated engine/rotorcraft control, torque converters, turbine design, airflow for rotorcraft torque control, bleed for lift flow, and transmissions and clutches.

  7. Converted Phase Elastic Migration Velocity Analysis

    E-print Network

    Shabelansky, Andrey Hanan

    2013-01-01

    Multi-component elastic seismic data collected at large offsets have the potential to be used in seismic imaging and velocity analysis. In this study, we present an approach for converted-phase elastic-transmission migration ...

  8. Integrated optical analog-to-digital converter

    E-print Network

    Khilo, Anatol

    2008-01-01

    An optically-sampled frequency-demultiplexed wideband analog-to-digital converter (ADC) which has potential to exceed the performance of electronic ADCs by orders of magnitude is studied analytically and numerically. The ...

  9. Integrated photonic analog-to-digital converters

    E-print Network

    Khilo, Anatol (Anatol M.)

    2011-01-01

    Accurate conversion of wideband multi-GHz analog signals into the digital domain has long been a target of analog-to-digital converter (ADC) developers, driven by applications in radar systems, software radio, medical ...

  10. Damping assembly for a torque converter clutch

    SciTech Connect

    Dull, D.C.

    1989-12-26

    This patent describes a turbine damped torque converter and clutch. It comprises: a pressure plate; a torque converter turbine; a torque converter impeller; means including a control chamber for the pressure plate means for controlling the apply and release of the clutch for engaging the clutch with the impeller; a torque converter output shaft; a planetary gear arrangement including an input gear drivingly connected with the pressure plate, a reaction gear drivingly connected with the turbine, an output member drivingly connected with the output shaft and pinion gear means meshing with the input gear and the reaction gear for drivingly interconnecting the turbine and the pressure plate at a drive ratio of the turbine to the pressure plate of less than 1:1; and one-way drive means disposed between the turbine and the output shaft for preventing the turbine from overrunning the output shaft.

  11. Application of microcontrollers to control HVDC converters

    Microsoft Academic Search

    Edmundo Barrera-Cardiel

    1993-01-01

    The author presents the design of the hardware and software of the AC\\/DC converter controllers for an HVDC transmission system. The structure of the converter controllers is based on a 16-b microcontroller. The microcontroller includes the facilities needed to support fast real-time control in a single chip. The main functions included in the terminal controllers are the control of the

  12. Multilevel converters for large electric drives

    Microsoft Academic Search

    Leon M. Tolbert; Fang Zheng Peng; Thomas G. Habetler

    1999-01-01

    This paper presents transformerless multilevel power converters as an application for high-power and\\/or high-voltage electric motor drives. Multilevel converters: (1) can generate near-sinusoidal voltages with only fundamental frequency switching; (2) have almost no electromagnetic interference or common-mode voltage; and (3) are suitable for large voltampere-rated motor drives and high voltages. The cascade inverter is a natural fit for large automotive

  13. Intermediate-Frequency-to-Video-Band Converter

    NASA Technical Reports Server (NTRS)

    Ham, N. C.; Chavez, V. M.; Chen, V. S.; Sato, T.

    1986-01-01

    Analog and digital circuits combined to frequency-convert from intermediate frequencies directly to video-band frequencies to meet stringent requirements. IF-to-video-band converter operates on principle of signal-band cancellation in phase-quadrature circuits. Downconverts intermediate frequencies directly to video-band frequencies to near-zero frequency with good image-band rejection and low phase variation within passband.

  14. A wavelength-convertible optical network

    Microsoft Academic Search

    Kuo-Chun Lee; V. O. K. Li

    1993-01-01

    Wavelength-division multiplexing (WDM) is emerging as the dominant technology in future all-optical networks. To efficiently use the wavelengths, wavelength converters are employed for a circuit-switched optical network in which a circuit can change its wavelength to resolve wavelength conflicts and to reuse the wavelengths. To improve the efficiency, a few converters are provided and shared by the incoming circuits in

  15. Novel zero-voltage-transition PWM converters

    Microsoft Academic Search

    Guichao Hua; Ching-Shan Leu; Yimin Jiang; Fred C. Y. Lee

    1994-01-01

    To date, soft-switching techniques applied to the PWM converters, with the exception of a few isolated cases, are subjected to either high switch voltage stresses or high switch current stresses, or both. A new class of zero-voltage-transition PWM converters is proposed, where both the transistor and the rectifier operate with zero-voltage switching and are subjected to minimum voltage and current

  16. Active-clamping quad-flyback converter

    Microsoft Academic Search

    B.-R. Lin; H.-K. Chiang; F.-P. Tsao

    2009-01-01

    An active-clamping quad-flyback converter is proposed to achieve zero voltage switching (ZVS) for all power switches. The secondary sides of quad-flyback converter are connected in parallel to share the load current. Thus, the transformer copper losses and the conduction losses on the output diodes are reduced. Active-clamping part including one auxiliary switch and one clamp capacitor can release the energy

  17. Soft Switching Circuit for Interleaved Boost Converters

    Microsoft Academic Search

    Gang Yao; Alian Chen; Xiangning He

    2007-01-01

    A zero-voltage switching-zero-current switching interleaved boost converter is proposed in this paper. An active circuit branch in parallel with the main switches is added and it is composed of an auxiliary switch and a snubber capacitor. By using this interleaved converter topology, zero current turn-on and zero voltage turn-off of the main switches can be achieved and the reverse-recovery loss

  18. Synthesis of Multilevel Converters Based on Single and\\/or Three-Phase Converter Building Blocks

    Microsoft Academic Search

    Jun Wen; Keyue Ma Smedley

    2008-01-01

    This paper synthesized a family of multilevel converters that is constructed by using multiple well-developed single- and\\/or three-phase converter building blocks. The resulting advantages include a modular structure that leads to convenient construction and maintenance as well as easy extension to higher voltage levels. One successful example from this family is the cascaded H-bridge converter, which is now widely used

  19. Design and loss comparison of matrix converters, and voltage-source converters for modern AC drives

    Microsoft Academic Search

    Steffen Bernet; Srinivas Ponnaluri; Ralph Teichmann

    2002-01-01

    This paper compares a matrix converter (MC) and a DC-voltage link converter with an active front end for a 7.5 kW, 460 V induction motor drive. Part count, semiconductor losses, input filter design, and protection aspects are discussed. It is shown that the matrix converter's semiconductor losses are smaller only at full load operation for the same silicon area in

  20. Direct AC-AC matrix converter based on three-phase voltage-source converter modules

    Microsoft Academic Search

    Mehrdad Kazerani; B. T. Ooi

    1993-01-01

    The original direct AC-AC matrix power converter employs bi-lateral switches. In this paper, a new topology, based on three-phase voltage-source power converter modules, is proposed. The total number of valves and diodes used is the same as in the original topology of nine bilateral switches. However, thanks to better knowledge of the voltage-source converter, it is possible to ensure safe

  1. Geologic map of the Alligator Ridge area, including the Buck Mountain East and Mooney Basin Summit quadrangles and parts of the Sunshine Well NE and Long Valley Slough quadrangles, White Pine County, Nevada

    USGS Publications Warehouse

    Nutt, Constance J.

    2000-01-01

    Data set describes the geology of Paleozoic through Quaternary units in the Alligator Ridge area, which hosts disseminated gold deposits. These digital files were used to create the 1:24,000-scale geologic map of the Buck Mountain East and Mooney Basin Summit Quadrangles and parts of the Sunshine Well NE and Long Valley Slough Quadrangles, White Pine County, east-central Nevada.

  2. Isolated and soft-switched power converter

    DOEpatents

    Peng, Fang Zheng (Knoxville, TN); Adams, Donald Joe (Knoxville, TN)

    2002-01-01

    An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.

  3. Fabrication and life testing of thermionic converters

    NASA Technical Reports Server (NTRS)

    Yang, L.; Bruce, R.

    1973-01-01

    An unfueled converter containing a chloride-fluoride duplex tungsten emitter of 4.78 eV vacuum work function was tested for 46,647 hours at an emitter temperature of 1973 K and an electrode power output of about 8 watts/sq cm. The test demonstrated the superior and stable performance of the (110) oriented tungsten emitter at high temperatures. Three 90 UC-10 ZrC(C/U = 1.04, tungsten additive = 4 wt %) fueled converters were fabricated and tested at an emitter temperature of 1873 K. Converter containing chloride-arc-cast duplex tungsten cladding showed temperature thermionic performance and slower rate of performance drop than converter containing chloride-fluoride duplex tungsten cladding. This is believed to be due to the superior fuel component diffusion resistance of the arc-cast tungsten substrate used in the fuel cladding. It was shown that a converter containing a carbide fueled chloride-arc-cast duplex tungsten emitter with an initial electrode power output of 6.80 watts/sq cm could still deliver an electrode power output of 6.16 watts/sq cm after 18,632 hours of operation at an emitter temperature of 1873 K.

  4. Materials technology for Stirling space power converters

    NASA Technical Reports Server (NTRS)

    Baggenstoss, William; Mittendorf, Donald

    1992-01-01

    This program was conducted in support of the NASA LeRC development of the Stirling power converter (SPC) for space power applications. The objectives of this contract were: (1) to perform a technology review and analyses to support the evaluation of materials issues for the SPC; (2) to evaluate liquid metal compatibility issues of the SPC; (3) to evaluate and define a transient liquid phase diffusion bonding (TLPDB) process for the SPC joints to the Udimet 720 heater head; and (4) to evaluate alternative (to the TLPDB) joining techniques. In the technology review, several aspects of the current Stirling design were examined including the power converter assembly process, materials joining, gas bearings, and heat exchangers. The supporting analyses included GLIMPS power converter simulation in support of the materials studies, and system level analysis in support of the technology review. The liquid metal compatibility study evaluated process parameters for use in the Stirling power converter. The alternative joining techniques study looked at the applicability of various joining techniques to the Stirling power converter requirements.

  5. IR filters for TPV converter modules

    NASA Astrophysics Data System (ADS)

    Horne, W. E.; Morgan, M. D.; Sundaram, V. S.

    1996-03-01

    This paper presents a TPV converter module for use with radioisotope heat sources such as the Department of Energy's General Purpose Heat Source (GPHS). The converter module utilizes an IR bandpass filter which transmits a band of energy at the optimum frequency for GaSb photovoltaic conversion and rejects long wavelength out of band energy with a broadband reflectance of greater than 98%. Recent progress in optimizing IR bandpass filters and photovoltaic cells for use in the TPV module is summarized. Measured data on the transmittance and reflectance of the filters, quantum efficiency of the PV cells both with and without the filters are presented. The results of using these measured results in an experimentally confirmed analytical model of the TPV converter module to calculate the performance of the optimized components are discussed. An economical pilot process for filter production is also described.

  6. Solar energy recorder. [for converter site selection

    NASA Technical Reports Server (NTRS)

    Lollar, R. B.; Mandt, R. R.

    1974-01-01

    A serious obstacle to the large-scale terrestrial application of solar energy lies in the scarcity of reliable data on the amount of solar energy at candidate converter sites. This paper describes a system designed to monitor and record, automatically, the values of the direct and total (sun and sky) solar radiation which would be seen by either tracking or fixed-type solar converters. A further pressing need addressed by the system is the means for efficiency testing and evaluation of solar cells, solar collectors and solar concentrator systems, under outdoor exposure to natural sunlight and weather conditions for extended periods. The design was accomplished in support of the Marshall Space Flight Center, NASA, where design concepts and materials for large-scale terrestrial solar energy converters are currently being evaluated.

  7. Kinetics : CatalyticConverters (4 Variations)

    NSDL National Science Digital Library

    The following table illustrates the changes in emissions requirements for automobiles: Pollutant 1970 Emissions 1990 Emissions CA ultra-low emissions C x H y 1.5 g/mile 0.25 g/mile 0.04 g/mile CO 15 g/mile 3.4 g/mile 1.7 g/mile NO x 3.1 g/mile 0.4 g/mile 0.2 g/mile Catalytic converters are used in automobiles to convert pollutants in engine emissions to benign products. Catalytic converters in today's automobiles are made of a porous ceramic brick that has been coated with catalysts, additives, stabilizers, and support materials. Corning has developed bricks that have very thin-walled channels with 600 channels per square inch. Which of the following research goals did they target?

  8. 40 CFR 91.319 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...of this section, test the efficiency of converters by means of...concentration. (3) Calculate the efficiency of the NOX converter as described...through the converter into the detector. Record the indicated concentration...this section. (b) The efficiency of the converter must be...

  9. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...of this section, test the efficiency of converters by means of...concentration. (3) Calculate the efficiency of the NOX converter as described...through the converter into the detector. Record the indicated concentration...this section. (b) The efficiency of the converter must be...

  10. ZCS PWM bidirectional converter with one auxiliary switch

    Microsoft Academic Search

    Ahmad Mousavi; Majid Pahlevaninezhad; Pritam Das; Praveen Jain

    2011-01-01

    Dc-dc bidirectional converters transfer energy between two different dc sources. Soft switching in both directions of operation has been difficult in non-isolated bidirectional converters. To achieve soft switching in the main switches in such converters, usually two independent auxiliary circuits with multiple auxiliary switches are used. A ZCS PWM bidirectional converter is proposed in this paper. In the proposed bidirectional

  11. Soft-switched DC\\/DC converter with PWM control

    Microsoft Academic Search

    R. Oruganti; Phua Chee Heng; K. G. Jeffrey Tan; A. C. Liew

    1993-01-01

    In this paper, a soft-switched power converter with two variations is discussed. An asymmetrical PWM control scheme is used to control the power converter under constant switching frequency operation. The modes of operation for both variations are discussed. The DC characteristics which can be used in design of the converters are also presented. Two 50 W converters were built to

  12. Time domain simulation of Sigma Delta A/D converters

    E-print Network

    Schilder, Frank

    : These stars are datatype conversion stars (float to matrix, matrix to float) that convert a single floatingTime domain simulation of Sigma Delta A/D converters using Ptolemy Frank Schilder TU Ilmenau no other A/D modulators or converters are considered here. For installing the A/D converter simulation

  13. Modeling and simulation of matrix converter\\/induction motor drive

    Microsoft Academic Search

    Takayoshi Matsuo; Steffen Bernet; R. Stephen Colby; Thomas A. Lipo

    1998-01-01

    Modeling and simulation of a matrix converter\\/induction motor drive are presented in this paper, which includes a three phase ac to ac matrix converter, an induction motor, a field oriented controller, filters and a power source. In addition, a developed precise loss calculation model for power converters is described with calculation results when it was applied to the matrix converter.

  14. Combination solar photovoltaic heat engine energy converter

    NASA Astrophysics Data System (ADS)

    Chubb, Donald L.

    1987-08-01

    A combination solar photovoltaic heat engine converter is proposed. Such a system is suitable for either terrestrial or space power applications. The combination system has a higher efficiency than either the photovoltaic array or the heat engine alone can attain. Advantages in concentrator and radiator area and receiver mass of the photovoltaic heat engine system over a heat-engine-only system are estimated. A mass and area comparison between the proposed space station organic Rankine power system and a combination PV-heat engine system is made. The critical problem for the proposed converter is the necessity for high temperature photovoltaic array operation. Estimates of the required photovoltaic temperature are presented.

  15. Ocean tide energy converter having improved efficiency

    Microsoft Academic Search

    Rainey

    1980-01-01

    A tide motor useful for converting periodic rising and falling water levels to useful work such as electric power generation includes a primary piston having a large enclosed chamber that can selectively be filled with air for generation of upward thrust when submerged in rising tidal water or filled with water for generating downward gravitational thrust when the piston is

  16. Efficient polarization converter for projection displays

    E-print Network

    to achieve a high level of conversion of unpolarized to polarized light, including the use of cholesteric LCEfficient polarization converter for projection displays W. C. Yip, H. C. Huang, and H. S. Kwok In the waveguiding limit, a twisted nematic liquid crystal cell behaves as an achromatic polarization rotator. We

  17. Converting Test Data to Counseling Information.

    ERIC Educational Resources Information Center

    Prediger, Dale J.

    Information from tests, when considered in the context of decision theory, can play an important role in vocational development. This role is primarily one of stimulating and facilitating exploratory behavior. Objective procedures for converting test data into counseling information are discussed and illustrated with special attention being given…

  18. Asymmetric Information and Financing with Convertibles

    Microsoft Academic Search

    Archishman Chakrabortyy; Bilge Y

    Asymmetric information regarding project prospects causes dilution, leading to adverse selection and ine-ciencies in the market for new investments. However, if the market obtains information about the flrm over time, issuing callable convertible securities with restrictive call provisions is optimal. Even when the market's information is noisy, such securities can be designed to make the payofi to new claimholders independent

  19. Asymmetric Information and Financing with Convertibles

    Microsoft Academic Search

    Archishman Chakraborty; Bilge Yilmaz

    2005-01-01

    Asymmetric information regarding project prospects causes dilution, leading to adverse selection and inefficiencies in the market for new investments. However, if the market obtains information about the firm over time, issuing callable convertible securities with restrictive call provisions is optimal. Even when the market's information is noisy, such securities can be designed to make the payoff to new claimholders independent

  20. Hybrid switch for resonant power converters

    SciTech Connect

    Lai, Jih-Sheng; Yu, Wensong

    2014-09-09

    A hybrid switch comprising two semiconductor switches connected in parallel but having different voltage drop characteristics as a function of current facilitates attainment of zero voltage switching and reduces conduction losses to complement reduction of switching losses achieved through zero voltage switching in power converters such as high-current inverters.

  1. STIFF: Converting Scientific FITS Images to TIFF

    NASA Astrophysics Data System (ADS)

    Bertin, Emmanuel

    2011-10-01

    STIFF is a program that converts scientific FITS1 images to the more popular TIFF2 format for illustration purposes. Most FITS readers and converters do not do a proper job at converting FITS image data to 8 bits. 8-bit images stored in JPEG, PNG or TIFF files have the intensities implicitely stored in a non-linear way. Most current FITS image viewers and converters provide the user an incorrect translation of the FITS image content by simply rescaling linearly input pixel values. A first consequence is that the people working on astronomical images usually have to apply narrow intensity cuts or square-root or logarithmic intensity transformations to actually see something on their deep-sky images. A less obvious consequence is that colors obtained by combining images processed this way are not consistent across such a large range of surface brightnesses. Though with other software the user is generally afforded a choice of nonlinear transformations to apply in order to make the faint stuff stand out more clearly in the images, with the limited selection of choices provides, colors will not be accurately rendered, and some manual tweaking will be necessary. The purpose of STIFF is to produce beautiful pictures in an automatic and consistent way.

  2. General Impedance Synthesis Using Simple Switching Converters

    E-print Network

    Tse, Chi K. "Michael"

    General Impedance Synthesis Using Simple Switching Converters Joe C. P. Liu, Chi K. Tse, Franki N Kong, Hong Kong Abstract-- A general impedance synthesizer using a minimum number of switching a lot of applications in power electronics. For instance, a resistance synthesizer can be used for power

  3. LLC resonant converter with two resonant tanks

    Microsoft Academic Search

    Eun-Soo Kim; Joo-Hoon Kim; Kwang-Ho Lee; Yong-Seog Jeon; Jae-Sam Lee; Dong-Young Huh

    2010-01-01

    To cope with the high power density and low cost in switching power supply, LLC resonant converters with the two resonant tank circuits composed of resonance capacitors and two transformers are proposed in this paper. Each transformers used for the proposed resonant circuits are parallel connected in the primary and series connected in the secondary to reduce the current unbalance.

  4. Catalytic Converters Maintain Air Quality in Mines

    NASA Technical Reports Server (NTRS)

    2014-01-01

    At Langley Research Center, engineers developed a tin-oxide based washcoat to prevent oxygen buildup in carbon dioxide lasers used to detect wind shears. Airflow Catalyst Systems Inc. of Rochester, New York, licensed the technology and then adapted the washcoat for use as a catalytic converter to treat the exhaust from diesel mining equipment.

  5. Resonantly two-photon pumped frequency converter

    NASA Technical Reports Server (NTRS)

    Harris, S. E.; Bloom, D. M.

    1974-01-01

    This letter describes a resonantly two-photon pumped frequency converter with application to the generation of tunable ultraviolet and vacuum ultraviolet radiation and also to infrared-to-visible up-conversion and imaging. Calculations show that up-conversion power efficiencies in excess of 100% should be obtained with tunable dye lasers having peak powers in the hundred watt to kilowatt range.

  6. Lathe converted for grinding aspheric surfaces

    NASA Technical Reports Server (NTRS)

    Larmer, J. W.; Levinsohn, M.; Mc Craw, D.; Pessagno, E. H.; Taub, F. J.

    1964-01-01

    A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

  7. Converting Waste Plastic to Hydrocarbon Fuel Materials

    Microsoft Academic Search

    Moinuddin Sarker

    2011-01-01

    The increased demand and high price for energy sources are driving efforts to convert organic compounds into useful hydrocarbon fuels. Although much of this work has focused on biomass, there are strong benefits to deriving fuels from waste plastic material. Waste plastic is abundant and its disposal creates large problems for the environment. Plastic does not break down in landfills,

  8. Converting Halpha Luminosities into Star Formation Rates

    Microsoft Academic Search

    Jan Pflamm-Altenburg; Carsten Weidner; Pavel Kroupa

    2007-01-01

    Star formation rates (SFRs) of galaxies are commonly calculated by converting the measured Halpha luminosities (LHalpha) into current SFRs. This conversion is based on a constant initial mass function (IMF) independent of the total SFR. As was recently recognized, the maximum stellar mass in a star cluster is limited by the embedded total cluster mass and, in addition, the maximum

  9. Multilevel converters for large electric drives

    SciTech Connect

    Tolbert, L.M.; Peng, F.Z.

    1997-11-01

    Traditional two-level high frequency pulse width modulation (PWM) inverters for motor drives have several problems associated with their high frequency switching which produces common-mode voltage and high voltage change (dV/dt) rates to the motor windings. Multilevel inverters solve these problems because their devices can switch at a much lower frequency. Two different multilevel topologies are identified for use as a converter for electric drives, a cascade inverter with separate dc sources and a back-to-back diode clamped converter. The cascade inverter is a natural fit for large automotive all electric drives because of the high VA ratings possible and because it uses several levels of dc voltage sources which would be available from batteries or fuel cells. The back to back diode damped converter is ideal where a source of ac voltage is available such as a hybrid electric vehicle. Simulation and experimental results show the superiority of these two converters over PWM based drives.

  10. Converting Waste into Clean Renewable Fuel

    E-print Network

    Converting Waste into Clean Renewable Fuel Presented at TechRealization August 27th, 2008 #12 and development located in Richland, WA Executive team headquartered in Bend, OR Exclusive license for Plasma ­ Waste and biomass gasification ­ Standard cleaning of synthesis gas ­ Ultra-deep cleaning of synthesis

  11. Convert natural gas into clean transportation fuels

    SciTech Connect

    Agee, M.A. [Syntroleum Corp., Tulsa, OK (United States)

    1997-03-01

    A new process economically converts natural gas into synthetic transportation fuels that are free of sulfur, metals, aromatics and are clear in appearance. The process, developed by Syntroleum Corp., is energy self-sufficient and can be implemented in sizes small enough to fit a large number of the world`s gas fields. The process is described.

  12. Converter production of clean and microalloyed steels

    Microsoft Academic Search

    P. I. Yugov; B. V. Molotilov

    2007-01-01

    Existing technologies for making steel in converters make it possible to obtain steels with very low contents of the “traditional” harmful impurities ? ?(H 2 ,N 2 ,O 2 ,P , S) ? 0.005 mass %. It was shown in [1] that the technical prerequisites exist for the commercial production of steels with impurity contents in the following ranges: C

  13. New modulation method for matrix converters

    Microsoft Academic Search

    Christian Klumpner; Frede Blaabjerg; Ion Boldea; Peter Nielsen

    2006-01-01

    This paper presents a new modulation method for matrix converters based on the indirect modulation model. During the switching period, the proposed modulation method uses a combination of only one active vector and a zero vector in the inversion stage to achieve minimum flux error, whereas in the rectification stage, a single current vector is selected according to the angle

  14. A new generalized direct matrix converter

    Microsoft Academic Search

    S. H. Hosseini; E. Babaei

    2001-01-01

    In this paper, the authors attempt to introduce a new modulation algorithm for matrix power converters, with an alternative PWM strategy, regardless of type of input and output (AC or DC), and also the number of input and output phases, by using suitable toggling matrix switches, such that favorable output patterns are achieved (with variable amplitudes and frequency). The switch

  15. Displacement angle control of matrix converter

    Microsoft Academic Search

    Jun Oyama; Xiarong Xia; Tsuyoshi Higuchi; Eiji Yamada

    1997-01-01

    The authors previously proposed and discussed a control method for matrix power converters in which instantaneous input voltages are used. The method can generate output voltages of 0.866 times the supply voltage. Control input current and output voltage of sinusoidal waveform can be obtained and can compensate the effect of fluctuation, asymmetry or harmonics in both the output voltage and

  16. Distribution and abundance of elkhorn coral, Acropora palmata, and prevalence of white-band disease at Buck Island Reef National Monument, St. Croix, US Virgin Islands

    NASA Astrophysics Data System (ADS)

    Mayor, Philippe A.; Rogers, Caroline S.; Hillis-Starr, Zandy M.

    2006-05-01

    In the 1970s and 1980s elkhorn coral, Acropora palmata, declined dramatically throughout the Caribbean primarily due to white-band disease (WBD). In 2005, elkhorn coral was proposed for listing as threatened under the US Endangered Species Act. WBD was first documented at Buck Island Reef National Monument (BIRNM). Together with hurricanes WBD reduced live elkhorn coral coverage by probably over 90%. In the past decade some recovery has been observed at BIRNM. This study assessed the distribution and abundance of elkhorn coral and estimated the prevalence of WBD at the monument. Within an area of 795 ha, we estimated 97,232 134,371 (95% confidence limits) elkhorn coral colonies with any dimension of connected live tissue greater than one meter, about 3% of which were infected by WBD. Despite some recovery, the elkhorn coral density remains low and WBD may continue to present a threat to the elkhorn coral population.

  17. Bucking Conventional Wisdom

    ERIC Educational Resources Information Center

    Brady, Marion

    2006-01-01

    In this article, the author discusses his contention that even the best of the best of American schools are not quality schools. He also observes that the curriculum that has been in place since 1892 was the main reason why schools cannot offer the best in quality education. He cites the ten problems that have plagued the American educational…

  18. Combustion converter development for topping and cogeneration applications

    NASA Astrophysics Data System (ADS)

    Goodale, D.; Lieb, D.; Miskolczy, G.; Moffat, A.

    This paper discusses the development of combustion-heated thermionic converters. Combustion applications pose a materials problem that does not exist for thermionic converters used in the vacuum of outer space. The high-temperature components of a thermionic converter must be protected from the oxidizing terrestrial environment. A layer of silicon carbide provides the most satisfactory protective coating, or 'hot shell', for the emitter and lead of a combustion-heated thermionic converter. Four areas of work aimed at developing combustion heated thermionic converters will be discussed: (1) improving the performance of the two-inch torispherical converter, (2) modifications to the converter so that it may be used in multi-converter modules, (3) the construction of a thermionic cogeneration test furnace, and (4) a converter life test in an oil-fired furnace.

  19. A square root analog to digital converter to optimally convert photonic signals for computed tomography

    E-print Network

    Bieniosek, Matthew (Matthew F.)

    2010-01-01

    The arrival of photons at a given location is a Poisson process with an associated shot noise which rises with the square root of the number of photons received. An analog-to-digital converter (ADC) with a square root ...

  20. Parametric study of minimum converter loss in an energy-storage dc-to-dc converter

    NASA Technical Reports Server (NTRS)

    Wong, R. C.; Owen, H. A., Jr.; Wilson, T. G.

    1982-01-01

    Through a combination of analytical and numerical minimization procedures, a converter design that results in the minimum total converter loss (including core loss, winding loss, capacitor and energy-storage-reactor loss, and various losses in the semiconductor switches) is obtained. Because the initial phase involves analytical minimization, the computation time required by the subsequent phase of numerical minimization is considerably reduced in this combination approach. The effects of various loss parameters on the optimum values of the design variables are also examined.

  1. Soft-switched PWM high-frequency with PFC converter using boost-flyback converter interleaved

    Microsoft Academic Search

    Carlos A. Gallo; J. A. Correa Pinto; L. C. de Freitas; V. J. Farias; E. A. A. Coelho

    2002-01-01

    This paper proposes as a power factor correction pre regulator converter an AC-DC interleaved boost-flyback using a nondissipative snubber and operating at 100 kHz per cell. That is composed by switches working in ZCS and ZVS way, controlled by PWM. By using interleaved converters, an overall reduction of the boost inductor can be obtained, reducing switching losses without increasing current

  2. Singular Perturbation Theory for DC–DC Converters and Application to PFC Converters

    Microsoft Academic Search

    Jonathan W. Kimball; Philip T. Krein

    2008-01-01

    Many control schemes for DC-DC converters begin with the assertion that inductor currents are ldquofastrdquo states and capacitor voltages are ldquoslowrdquo states. This assertion must be true for power factor correction (PFC) converters to allow independent control of current and voltage, and is important for many other applications. In the present study, singular perturbation theory is applied to two-state switching-power

  3. A high speed CMOS A/D converter

    NASA Technical Reports Server (NTRS)

    Wiseman, Don R.; Whitaker, Sterling R.

    1992-01-01

    This paper presents a high speed analog-to-digital (A/D) converter. The converter is a 7 bit flash converter with one half LSB accuracy. Typical parts will function at approximately 200 MHz. The converter uses a novel comparator circuit that is shown to out perform more traditional comparators, and thus increases the speed of the converter. The comparator is a clocked, precharged circuit that offers very fast operation with a minimal offset voltage (2 mv). The converter was designed using a standard 1 micron digital CMOS process and is 2,244 microns by 3,972 microns.

  4. Optical analog-to-digital converter

    DOEpatents

    Vawter, G. Allen (Corrales, NM); Raring, James (Goleta, CA); Skogen, Erik J. (Albuquerque, NM)

    2009-07-21

    An optical analog-to-digital converter (ADC) is disclosed which converts an input optical analog signal to an output optical digital signal at a sampling rate defined by a sampling optical signal. Each bit of the digital representation is separately determined using an optical waveguide interferometer and an optical thresholding element. The interferometer uses the optical analog signal and the sampling optical signal to generate a sinusoidally-varying output signal using cross-phase-modulation (XPM) or a photocurrent generated from the optical analog signal. The sinusoidally-varying output signal is then digitized by the thresholding element, which includes a saturable absorber or at least one semiconductor optical amplifier, to form the optical digital signal which can be output either in parallel or serially.

  5. Strained quantum well photovoltaic energy converter

    NASA Technical Reports Server (NTRS)

    Freundlich, Alexandre (Inventor); Renaud, Philippe (Inventor); Vilela, Mauro Francisco (Inventor); Bensaoula, Abdelhak (Inventor)

    1998-01-01

    An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output.

  6. Analog current mode analog/digital converter

    NASA Technical Reports Server (NTRS)

    Hadidi, Khayrollah (Inventor)

    1996-01-01

    An improved subranging or comparator circuit is provided for an analog-to-digital converter. As a subranging circuit, the circuit produces a residual signal representing the difference between an analog input signal and an analog of a digital representation. This is achieved by subdividing the digital representation into two or more parts and subtracting from the analog input signal analogs of each of the individual digital portions. In another aspect of the present invention, the subranging circuit comprises two sets of differential input pairs in which the transconductance of one differential input pair is scaled relative to the transconductance of the other differential input pair. As a consequence, the same resistor string may be used for two different digital-to-analog converters of the subranging circuit.

  7. Component technology for Stirling power converters

    SciTech Connect

    Thieme, L.G.

    1994-09-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling space power program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for a DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their program goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. This paper will present an overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings.

  8. Component technology for stirling power converters

    NASA Technical Reports Server (NTRS)

    Thieme, Lanny G.

    1991-01-01

    NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE/Sandia program to develop Stirling converters for solar terrestrial power producing electricity for the utility grid. The primary contractors for the space power and solar terrestrial programs develop component technologies directly related to their goals. This Lewis component technology effort, while coordinated with the main programs, aims at longer term issues, advanced technologies, and independent assessments. An overview of work on linear alternators, engine/alternator/load interactions and controls, heat exchangers, materials, life and reliability, and bearings is presented.

  9. An overview of sigma-delta converters

    Microsoft Academic Search

    PERVEZ M. AZIZ; HENRIK V. SORENSEN; JAN VAN DER SPIEGEL

    1996-01-01

    Using sigma-delta A\\/D methods, high resolution can be obtained for only low to medium signal bandwidths. This article describes conventional A\\/D conversion, as well as its performance modeling. We then look at the technique of oversampling, which can be used to improve the resolution of classical A\\/D methods. We discuss how sigma-delta converters use the technique of noise shaping in

  10. Converting Centrifugal Chillers to HCFC-123 

    E-print Network

    Siebert, B.

    1994-01-01

    designed for CFC II by five to 20 percent. In addition, HCFC-123 is a more active solvent that CFC-II. It can erode seals, gaskets and components not designed to resist it and it may degrade the insulation surrounding compressor motor windings. While... new equipment designed for HCFC-123 has overcome the capacity and efficiency losses through improved heat transfer surfaces and compressor enhancement, these differences must be considered in any plans to convert existing chillers from CFC...

  11. Fracture imaging with converted elastic waves

    SciTech Connect

    Nihei, K.T.; Nakagawa, S.; Myer, L.R.

    2001-05-29

    This paper examines the seismic signatures of discrete, finite-length fractures, and outlines an approach for elastic, prestack reverse-time imaging of discrete fractures. The results of this study highlight the importance of incorporating fracture-generated P-S converted waves into the imaging method, and presents an alternate imaging condition that can be used in elastic reverse-time imaging when a direct wave is recorded (e.g., for crosswell and VSP acquisition geometries).

  12. Torque converter slipping clutch and control

    SciTech Connect

    Wonn, Q.E.

    1987-02-17

    This patent describes a controlled slip torque converter and clutch comprising; an input shell; a torque converter means having an impeller drivingly connected with the input shell, a turbine and a stator disposed for toroidal flow, the torque converter means transmitting drive torque from the impeller to the turbine in a slipping relation; clutch means engageable in response to fluid pressure to limit the slip relation between the impeller and turbine and being disposed in drive relation between the input shell and the turbine and cooperating therewith to form clutch apply chamber means and clutch release chamber means; variable flow restriction means including spring means disposed between the clutch apply chamber means and the release chamber means for providing a controlled flow from the apply chamber means to the release chamber means; and viscous damper means disposed in parallel relation with the spring means on the variable flow restriction means and being responsive to torque disturbances at the clutch means and the turbine to restrict the rate at which the flow restriction means varies.

  13. 7 CFR 12.32 - Converted wetland identification criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Converted wetland identification criteria. 12.32 Section 12...Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland...

  14. 7 CFR 12.32 - Converted wetland identification criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Converted wetland identification criteria. 12.32 Section 12...Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland...

  15. A low-power reconfigurable analog-to-digital converter

    E-print Network

    Gulati, Kush

    2001-01-01

    This thesis presents the concept, theory and design of a low power CMOS analog-to-digital converter that can digitize signals over a wide range of bandwidth and resolution with adaptive power consumption. The converter ...

  16. An economical single to three phase converter for induction motors 

    E-print Network

    Di Zerega, Philp Van Uytandaele

    1994-01-01

    There are several different types of single to three phase converters for induction motors available today. However, many of the presently available phase converters suffer from disadvantages such as high cost or low performance. An economical...

  17. Highly linear, sensitive analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Cox, J.; Finley, W. R.

    1969-01-01

    Analog-to-digital converter converts 10 volt full scale input signal into 13 bit digital output. Advantages include high sensitivity, linearity, low quantitizing error, high resistance to mechanical shock and vibration loads, and temporary data storage capabilities.

  18. 3. Rear (north) and east elevations of converted chicken house, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. Rear (north) and east elevations of converted chicken house, with smokehouse, cooling (well) house, and residence in background - Henry E. Williams Farmstead, Converted Chicken House, East of Residence & Smokehouse, Cedar Point, Chase County, KS

  19. New transformerless, scalable Modular Multilevel Converters for HVDC-transmission

    Microsoft Academic Search

    Silke Allebrod; Roman Hamerski; Rainer Marquardt

    2008-01-01

    In this paper a novel concept of high voltage direct current converter (HVDC) is presented employing the modular multilevel converter (M2C). Converters using IGBT-power devices, are getting increased importance in order to meet the global needs for reliable and environment friendly power supply and distribution. The new topology is compared to HVDC-transmission based on two level (2level) converters with direct

  20. Energy efficient C-dump converters for switched reluctance motors

    Microsoft Academic Search

    Sayeed Mir; Iqbal Husain; Malik E. Elbuluk

    1996-01-01

    Two energy-efficient converter topologies, derived from the conventional C-dump converter, are proposed for switched reluctance motor (SRM) drives. The proposed topologies overcome the limitations of the conventional C-dump converter, and could reduce the overall cost of the SRM drive. The voltage ratings of the dump capacitor and the switching devices in the proposed converters are reduced to the supply voltage

  1. A Composite PWM Control Strategy for Boost Converter

    NASA Astrophysics Data System (ADS)

    Qingfeng, Liu; Zhaoxia, Leng; Jinkun, Sun; Huamin, Wang

    In order to improve the control performance of boost converter with large signal disturbance, a composite PWM control strategy for boost converter operating in continuous condition mode (CCM) was proposed in this paper. The parasitical loss of Boost converter was analyzed and a loss compensation strategy was adopted to design feed-forward tracker for converter. The composite PWM controller consisted of the tracker and PID controller. Simulation and experiment results validated the validity of the control strategy presented in this paper.

  2. Improved soft-switching ZVT converters with active snubber

    Microsoft Academic Search

    Ray L. Lin; Yiqing Zhao; Fred C. Lee

    1998-01-01

    A new family of improved soft-switching ZVT power converters with an active snubber is developed in order to improve the efficiency of conventional ZVT power converters using a feedback inductor. Besides the ZVT turn-on performance of the main switch, the improved ZVT soft-switching power converters have less turn-off switching loss of the main switch than do conventional ZVT converters using

  3. Multiport Converter Topologies for Distributed Energy System Applications 

    E-print Network

    Hawke, Joshua

    2014-07-28

    technologies into singular systems, there is a growing appetite for multiport converter (MPC) design. In response, three unique DER MPC topologies are presented: the power sharing converter (PSC), the multi-level nine switch converter (ML9SC), and the modular...

  4. Development of a Unipolar Converter for Variable Reluctance Motor Drives

    Microsoft Academic Search

    Mehrdad Ehsani; James T. Bass; Timothy J. E. Miller; Robert L. Steigerwald

    1987-01-01

    A new converter concept for driving the switched reluctance motor has been developed. This converter has only one switching device per phase, uses a unipolar dc supply, returns all the trapped energy to the source, and does not require bifilar windings; it is called a C-dump converter because the trapped energy is dumped in a capacitor and then returned to

  5. Efficient Wavelength Routing in Trees with Low--Degree Converters

    E-print Network

    Caragiannis, Ioannis

    converters of constant degree. 1. Introduction Optical fiber is rapidly becoming the standard transmission consists in first converting the optical signal to electronic and then back to optical on the desired announced [12, 25]. A wavelength converter is a device that allows the conversion of optical signals from o

  6. Life cycle assessment of a catalytic converter for passenger cars

    Microsoft Academic Search

    Wathanyu Amatayakul; Olle Ramnäs

    2001-01-01

    A life cycle assessment of a typical ceramic three-way catalytic converter manufactured for a Swedish passenger car is performed. The environmental impacts occurring in the life cycle of a catalytic converter, encompassing the extraction of raw materials, production of a catalytic converter, use phase, etc. are assessed. They are compared with the environmental benefits assessed throughout an average service lifetime

  7. LLC resonant converter for front end DC\\/DC conversion

    Microsoft Academic Search

    Bo Yang; Fred C. Lee; Alpha J. Zhang; Guisong Huang

    2002-01-01

    A new LLC resonant converter is proposed for front end DC\\/DC conversion in a distributed power system. Three advantages are achieved with this resonant converter. First, ZVS turn on and low turn off current of MOSFETs are achieved. The switching loss is reduced so we can operate the converter at higher switching frequency. The second advantage is that with this

  8. 78 FR 40132 - Wave Energy Converter Prize Administration Webinar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ...Converter (WEC) devices in a wave tank test. The WWTPO anticipates...implementation of a prize challenge for wave energy converters. The information...this notice will be used for internal DOE planning including the potential...involved in the development of wave energy converters, (2)...

  9. Soft-switched DC\\/DC converter with PWM control

    Microsoft Academic Search

    Ramesh Oruganti; Phua Chee Heng; Jeffrey Tan Kian Guan; Liew Ah Choy

    1998-01-01

    In this paper, a new power converter with two variations is proposed. A novel asymmetrical pulse-width-modulation (PWM) control scheme is used to control the power converter under constant switching frequency operation. The modes of operation for both variations are discussed. The DC characteristics, which can be used in the design of the power converters, are also presented. Two 50 W

  10. Combustion converter development for topping and cogeneration applications

    Microsoft Academic Search

    D. Goodale; D. Lieb; G. Miskolczy; A. Moffat

    1983-01-01

    This paper discusses the development of combustion-heated thermionic converters. Combustion applications pose a materials problem that does not exist for thermionic converters used in the vacuum of outer space. The high-temperature components of a thermionic converter must be protected from the oxidizing terrestrial environment. A layer of silicon carbide provides the most satisfactory protective coating, or 'hot shell', for the

  11. A novel matrix converter topology with simple commutation

    Microsoft Academic Search

    Lixiang Wei; T.A. Lipo

    2001-01-01

    The matrix converter is very simple in structure and has powerful controllability. However, the commutation problem and complicated PWM method keep it from being utilized in industry. This paper discloses a novel matrix topology with advantages over the usual matrix converter topology. Firstly, it has the same performance as a conventional matrix converter in terms of voltage transfer ratio capacity,

  12. Application of the matrix converter to induction motor drives

    Microsoft Academic Search

    Takayoshi Matsuo; Steffen Bernet; R. S. Colby; T.A. Lipo

    1996-01-01

    This paper presents the technical issues of applying the matrix power converter to field-oriented induction motor drives. A newly developed matrix power converter switching sequence combination is described in detail, the purpose of which is to minimize harmonic components of the matrix power converter input currents. It is demonstrated that small size capacitors work efficiently as input filters. Matrix power

  13. A new matrix converter-motor (MCM) for industry applications

    Microsoft Academic Search

    Christian Klumpner; Peter Nielsen; Ion Boldea; Frede Blaabjerg

    2000-01-01

    The trend in electrical drives is to integrate the frequency converter, the electrical motor and even the gear or the pump into a single unit, in order to reduce the costs and to increase the overall efficiency and the equipment reliability. This paper presents the first integrated regenerative frequency converter-motor for industry applications, based on a matrix converter topology. The

  14. The Matrix Converter Drive Performance Under Abnormal Input Voltage Conditions

    E-print Network

    Hava, Ahmet

    The Matrix Converter Drive Performance Under Abnormal Input Voltage Conditions Jun-Koo Kang-8530, Japan e-mail:kang@yaskawa.co.jp Abstract- The matrix converter is a direct frequency conversion device disturbances can degrade its performance and reliability. In this paper, the behavior of the matrix converter

  15. A new matrix converter motor (MCM) for industry applications

    Microsoft Academic Search

    Christian Klumpner; Peter Nielsen; Ion Boldea; Frede Blaabjerg

    2002-01-01

    The trend in electrical drives is to integrate the frequency converter, the electrical motor, and even the gear or the pump into a single unit, in order to reduce the costs, to increase the overall efficiency and the equipment reliability. This paper presents the first integrated regenerative frequency converter motor for industry applications, based on a matrix converter topology. The

  16. High power density dc/dc converter: Selection of converter topology

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.

    1990-01-01

    The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

  17. Optical analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Evanchuk, Vincent L. (Inventor)

    1984-01-01

    A method and apparatus for converting the intensity of an unknown optical signal (B) into an electrical signal in digital form utilizes two elongated optical attenuators (11, 13), one for the unknown optical signal from a source (10) and one for a known optical signal (A) from a variable source (12), a plurality of photodetectors (e.g., 17, 18) along each attenuator for detecting the intensity of the optical signals, and a plurality of comparators (e.g., 21) connected to the photodetectors in pairs to determine at what points being compared the attenuated known signal equals the attenuated unknown signal. The intensity of the unknown relative to the known is thus determined by the output of a particular comparator. That output is automatically encoded to a relative intensity value in digital form through a balancing feedback control (24) and encoder (23). The digital value may be converted to analog form in a D-to-A converter (27) and used to vary the source of the known signal so that the attenuated intensity of the known signal at a predetermined point (comparator 16) equals the attenuated intensity of the unknown signal at the predetermined point of comparison. If the known signal is then equal to the unknown, there is verification of the analog-to-digital conversion being complete. Otherwise the output of the comparator indicating equality at some other point along the attenuators will provide an output which is encoded and added, through an accumulator comprised of a register (25) and an adder (26), to a previous relative intensity value thereby to further vary the intensity of the known signal source. The steps are repeated until full conversion is verified.

  18. Bolometric THz-to-IR converter for terahertz imaging

    NASA Astrophysics Data System (ADS)

    Kuznetsov, Sergey A.; Paulish, Andrey G.; Gelfand, Alexander V.; Lazorskiy, Pavel A.; Fedorinin, Victor N.

    2011-07-01

    The quasi-optical bolometric converter of terahertz (THz) waves into infrared (IR) radiation is proposed and experimentally investigated. The converter includes an ultra-thin THz absorber (with a thickness 1/50 of the operating free-space wavelength) based on an artificial impedance surface with close to perfect resonant absorptivity at 0.3 THz and a high-performance IR emissive layer. Absorption of THz waves induces converter heating that yields enhancement of IR emission from the emissive layer. The experimental testing of the THz-to-IR converter demonstrates the applicability of a converter to THz imaging with spectral and polarization discrimination in real-time operation.

  19. Dead time optimization method for power converter

    NASA Astrophysics Data System (ADS)

    Deselaers, C.; Bergmann, U.; Gronwald, F.

    2013-07-01

    This paper introduces a method for dead time optimization in variable speed motor drive systems. The aim of this method is to reduce the conduction time of the freewheeling diode to a minimum without generation of cross conduction. This results in lower losses, improved EMC, and less overshooting of the phase voltage. The principle of the method is to detect beginning cross currents without adding additional components in the half bridge like resistors or inductances. Only the wave shape of the phase voltage needs to be monitored during switching. This is illustrated by an application of the method to a real power converter.

  20. Converting VSAM in COBOL to embedded SQL

    SciTech Connect

    Huang, Hai; Wang, Yamin; Tsai, Wei-Tek [Univ. of Minnesota, Minneapolis, MN (United States)

    1996-12-31

    VSAM databases we widely used on IBM mainframe systems. As new technology, such as relational database and client-server computing, becomes popular, there is a need to reengineer the VSAM databases to relational databases. This paper addresses the issues on converting COBOL programs that access VSAM database to COBOL programs that access relational databases with embedded SQL. It proposed a semi-automatic approach to the conversion of VSAM data sets to SQL tables and VSAM operations in COBOL program to embedded SQL queries. The proposed approach has been experimented on several industrial COBOL programs and a tool implementing the approach is under development.

  1. A wideband 12 GHz down converter

    NASA Technical Reports Server (NTRS)

    Newman, B. A.; Rosenbaum, F. J.

    1972-01-01

    The design, fabrication, and evaluation of a single ended 12 GHz down-converter suitable for use in a low cost satellite ground terminal is described. The mixer uses waveguide, coaxial and MIC (microwave integrated circuit) transmission line components. Theoretical and experimental analyses of several microstrip circuit elements are presented including the traveling wave-directional filter, quarter wave-length proximity directional coupler, low pass filter and the quarterwave band stop filter. The optimum performance achieved for the mixer using a packaged diode was 9.4 db conversion loss and a bandwidth of 275 MHz.

  2. Bifurcation behaviours of peak current controlled PFC boost converter

    NASA Astrophysics Data System (ADS)

    Ren, Hai-Peng; Liu, Ding

    2005-07-01

    Bifurcation behaviours of the peak current controlled power-factor-correction (PFC) boost converter, including fast-scale instability and low-frequency bifurcation, are investigated in this paper. Conventionally, the PFC converter is analysed in continuous conduction mode (CCM). This prevents us from recognizing the overall dynamics of the converter. It has been pointed out that the discontinuous conduction mode (DCM) can occur in the PFC boost converter, especially in the light load condition. Therefore, the DCM model is employed to analyse the PFC converter to cover the possible DCM operation. By this way, the low-frequency bifurcation diagram is derived, which makes the route from period-double bifurcation to chaos clear. The bifurcation diagrams versus the load resistance and the output capacitance also indicate the stable operation boundary of the converter, which is useful for converter design.

  3. Float pump offshore wave energy converters

    SciTech Connect

    Nielsen, K. [Danish Wave Power Aps, Virum (Denmark)

    1996-12-31

    This paper will describe the numerical design models developed by DWP and ES-Consult as part of the Off-shore Wave Energy Converter project OWEC-1 supported by the European Union under the JOULE initiative. Offshore Wave Power Plants composed of float pump systems, has been investigated. Modeling techniques required to provide reliable methods for the predicted hydrodynamic behavior of the floats, their performance has been assessed and standardized criteria and techniques for the design has been provided. The systems investigated and the numerical time domain models developed will be described. The DWP/ES-Consult design models include both heave and surge motion of the device motion. The hydrodynamics are based on the long wave approximation of wave exiting forces as well as nonlinear drag and lift-forces, limits for the buoyancy force and variation of added mass with submergence are included in the calculations. The numerical models developed by DWP/ES-Consult are intended as tools for the structural design. The results in medium waves are compared to more exact hydrodynamic models (heave only) developed at Chalmars University and at NTH norwegian Technical University. Results are compared to model tests and real sea measurements. The design of the float geometry`s and power takeoff has not been optimized. The scope has been to compare and provide tools and guidelines for time domain modeling of offshore wave energy converters as a basis for further optimization.

  4. Resonant Tunneling Analog-To-Digital Converter

    NASA Technical Reports Server (NTRS)

    Broekaert, T. P. E.; Seabaugh, A. C.; Hellums, J.; Taddiken, A.; Tang, H.; Teng, J.; vanderWagt, J. P. A.

    1995-01-01

    As sampling rates continue to increase, current analog-to-digital converter (ADC) device technologies will soon reach a practical resolution limit. This limit will most profoundly effect satellite and military systems used, for example, for electronic countermeasures, electronic and signal intelligence, and phased array radar. New device and circuit concepts will be essential for continued progress. We describe a novel, folded architecture ADC which could enable a technological discontinuity in ADC performance. The converter technology is based on the integration of multiple resonant tunneling diodes (RTD) and hetero-junction transistors on an indium phosphide substrate. The RTD consists of a layered semiconductor hetero-structure AlAs/InGaAs/AlAs(2/4/2 nm) clad on either side by heavily doped InGaAs contact layers. Compact quantizers based around the RTD offer a reduction in the number of components and a reduction in the input capacitance Because the component count and capacitance scale with the number of bits N, rather than by 2 (exp n) as in the flash ADC, speed can be significantly increased, A 4-bit 2-GSps quantizer circuit is under development to evaluate the performance potential. Circuit designs for ADC conversion with a resolution of 6-bits at 25GSps may be enabled by the resonant tunneling approach.

  5. Serial Pixel Analog-to-Digital Converter

    SciTech Connect

    Larson, E D

    2010-02-01

    This method reduces the data path from the counter to the pixel register of the analog-to-digital converter (ADC) from as many as 10 bits to a single bit. The reduction in data path width is accomplished by using a coded serial data stream similar to a pseudo random number (PRN) generator. The resulting encoded pixel data is then decoded into a standard hexadecimal format before storage. The high-speed serial pixel ADC concept is based on the single-slope integrating pixel ADC architecture. Previous work has described a massively parallel pixel readout of a similar architecture. The serial ADC connection is similar to the state-of-the art method with the exception that the pixel ADC register is a shift register and the data path is a single bit. A state-of-the-art individual-pixel ADC uses a single-slope charge integration converter architecture with integral registers and “one-hot” counters. This implies that parallel data bits are routed among the counter and the individual on-chip pixel ADC registers. The data path bit-width to the pixel is therefore equivalent to the pixel ADC bit resolution.

  6. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (inventor)

    1993-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  7. Forback DC-to-DC converter

    NASA Technical Reports Server (NTRS)

    Lukemire, Alan T. (inventor)

    1995-01-01

    A pulse-width modulated DC-to-DC power converter including a first inductor, i.e. a transformer or an equivalent fixed inductor equal to the inductance of the secondary winding of the transformer, coupled across a source of DC input voltage via a transistor switch which is rendered alternately conductive (ON) and nonconductive (OFF) in accordance with a signal from a feedback control circuit is described. A first capacitor capacitively couples one side of the first inductor to a second inductor which is connected to a second capacitor which is coupled to the other side of the first inductor. A circuit load shunts the second capacitor. A semiconductor diode is additionally coupled from a common circuit connection between the first capacitor and the second inductor to the other side of the first inductor. A current sense transformer generating a current feedback signal for the switch control circuit is directly coupled in series with the other side of the first inductor so that the first capacitor, the second inductor and the current sense transformer are connected in series through the first inductor. The inductance values of the first and second inductors, moreover, are made identical. Such a converter topology results in a simultaneous voltsecond balance in the first inductance and ampere-second balance in the current sense transformer.

  8. Converting non-classicality into entanglement

    E-print Network

    Nathan Killoran; Frank E. S. Steinhoff; Martin B. Plenio

    2015-05-27

    Quantum mechanics exhibits a wide range of non-classical features, of which entanglement in multipartite systems takes a central place. Other notions of non-classicality are also important, especially for non-composite systems. Yet the relationship between entanglement and other types of non-classicality remains to be clarified. In this work we show that, in fact, several general forms of single-system non-classicality are faithfully convertible into entanglement. Specifically, we prove that there is a physical operation which transforms all given non-classical states into entangled states, while the corresponding classical states become separable. Our results apply to two broad scenarios, one which is discrete and one which is continuous. In the discrete setting, the classical states can be any finite linearly independent set. For the continuous setting, the pertinent classical states are `symmetric coherent states,' connected with symmetric representations of the group SU(K). These results generalize and link convertibility properties from the resource theory of coherence, spin coherent states, and optical coherent states, while also revealing important connections between local and non-local quantum correlations.

  9. Korean R&D on the converter controller for ITER AC\\/DC converters

    Microsoft Academic Search

    J. H. Suh; J. S. Oh; J. Choi; E. H. Song; G. S. Lee; K. S. Eom; J. Goff; J. Tao; P. Fu

    2011-01-01

    The ITER coil power supplies provide controlled DC current to charge and stabilize the current in a toroidal field (TF) coil, and to establish and control the currents in a central solenoid (CS) module, polo ida I field (PF) coils, and correction coils (CC) for the position and shape control of plasma. They consist of different types of AC\\/DC converters

  10. Average Modeling Technique for Switched Capacitor Converters Including Large Signal Dynamics and Small Signal Responses

    E-print Network

    Average Modeling Technique for Switched Capacitor Converters Including Large Signal Dynamics and small signal response of Switched Capacitor Converters (SCC) was developed and tested. The proposed Terms -- Switched Capacitor Converter, SCC, modeling, dynamic behavior, power converter, small signal

  11. Centrifuges help convert factory sludge into profit

    SciTech Connect

    Gressel, A.

    1994-09-01

    Most industrial facilities must determine what to do with used oil and oily wastewater or sludge. Constructing on-site treatment facilities requires a sizable capital investment. An alternative is to pay someone to haul away the sludge for treatment and disposal. In either case, generators still are responsible for disposing the material in compliance with regulations. The Cleveland facility of Research Oil Co., a waste oil and industrial wastewater processing company, processes more than 50 million gallons of industrial waste annually. Of this volume, no more than 20% is oil; the remaining portion is water. The company reclaims fuel oil and lubricants, and converts the remainder into clean, treated, dry solids and high-Btu organic fuel for cement kilns. High-phosphate solids are used in fertilizers; other solids are disposed in secure landfills.

  12. Numerical study of porous media thermoelectric converter

    SciTech Connect

    Kosaka, Kenichirou; Yamada, Akira

    1996-12-31

    Thermoelectric conversion is direct conversion technology that has characteristics of being maintenance free. However, the efficiency of the conventional bulk semiconductor thermoelectric device is about 20% for ideal theoretical calculation, and less than 5% for an actual application. The efficiency is very low because the heat conduction in the device and the Joule loss are too large compared with the Peltier heat which is changed into the electric power. The thermoelectric device made by porous media is heated by the radiation and maintains a large temperature difference by the gas which passes in the porous device. Therefore, the influence of the heat conduction in the thermoelectric device is small and the improvement of the conversion efficiency can be attempted. In this paper, the authors report the calculated results and the performance of thermoelectric converter made with porous media.

  13. Transdermal delivery of Angiotensin Converting Enzyme inhibitors.

    PubMed

    Helal, Fouad; Lane, Majella E

    2014-09-01

    The Angiotensin Converting Enzyme (ACE) inhibitor class of drugs has been in clinical use since the 1970s for the management of all grades of heart failure, hypertension, diabetic nephropathy and prophylaxis of cardiovascular events. Because of the advantages associated with transdermal delivery compared with oral delivery many researchers have investigated the skin as a portal for administration of ACE inhibitors. This review summarises the various studies reported in the literature describing the development and evaluation of transdermal formulations of ACE inhibitors. Captopril, enalapril maleate, lisinopril dihydrate, perindopril erbumine and trandolapril are the most studied in connection with transdermal preparations. The methodologies reported are considered critically and the limitations of the various skin models used are also highlighted. Finally, opportunities for novel transdermal preparations of ACE inhibitor drugs are discussed with an emphasis on rational formulation design. PMID:24657822

  14. Polarization converters in highly birefringent microfibers.

    PubMed

    Xuan, HaiFeng; Ma, Jun; Jin, Wa; Jin, Wei

    2014-02-10

    A novel type of polarization converters (PCs) based on highly birefringent (Hi-Bi) microfibers is presented. Analytical formulation based on the Jones Matrix method and a numerical code based on the Full Vectorial Finite Difference Beam Propagation Method are developed to analyze the polarization evolutions in such PCs. Two different design configurations, namely the "one-side" and "two-side" perturbation configurations, are studied by use of the two methods, and the results obtained agree well with each others. The PCs can be flexibly designed to have different operating wavelengths, spectral bandwidths, and devices lengths. A particular PC based on an elliptical microfiber demonstrates a bandwidth of ? 600 nm around 1550 nm with a device length of ? 150 ?m. PMID:24663656

  15. Synchronously Driven Power Converter Controller Solution for MedAustron

    E-print Network

    Šepetavc, Luka; Tav?ar, Rok; Moser, Roland; Gutleber, Johannes

    2011-01-01

    MedAustron is an ion beam cancer therapy and research centre currently under construction in Wiener Neustadt, Austria. This facility features a synchrotron particle accelerator for light ions. Cosylab is closely working together with MedAustron on the development of a power converter controller (PCC) for the 260 deployed power converters – power supplies. Power converters deliver power to magnets used for focusing and steering particle beams. We have designed and developed software and hardware which allows integration of different types of power converters into MedAustron's control system (MACS). PCC's role is to synchronously control and monitor connected power converters. Custom real-time fibre optics link and modular front end devices have been designed for this purpose. Modular front end devices make it possible to interface with almost any type of power converter – with or without built in regulation logic. We implemented realtime mechanisms and a dedicated real-time fibre link to ...

  16. An integrated flyback converter for DC uninterruptible power supply

    SciTech Connect

    Ma, K.W. [Ericsson Ltd., Quarry Bay (Hong Kong). Energy System Div.; Lee, Y.S. [Hong Kong Polytechnic Univ., Kowloon (Hong Kong). Dept. of Electronic Engineering

    1996-03-01

    An integrated flyback converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SMPS) is presented. This converter has a high voltage main power input and a low voltage backup battery input. DC output is obtained form the main input via a flyback converter during normal operation and from the backup battery via another flyback converter when input power fails. High conversion efficiency is achieved in normal, backup, and charging modes as there is only a single dc-dc conversion in each mode. The converter circuit is very simple, with two switching transistors, a relay for mode switching, and a single magnetic structure only. This new design offers substantial improvement in efficiency, size, and cost over the conventional cascade of UPS and SMPS due to single voltage conversion, high frequency switching, and removal of design redundancy. The operation, design, analysis, and experimental results of the converter are presented.

  17. Experimental evaluation of losses in magnetic components for power converters

    Microsoft Academic Search

    J. A. Ferreira; J. D. van Wyk

    1988-01-01

    Optimization of copper and core losses is an important aspect of converter technology in the trend towards high frequency and high power density, ranging from high-frequency high-Q inductors in resonant converters, to high-power thyristor converters that impress complex current waveforms with significant harmonic content on line frequency transformers and electric machines. Core materials are obtained from manufacturers, so that a

  18. Application of RF Circuit Design Principles to Distributed Power Converters

    Microsoft Academic Search

    Ronald J. Gutmann

    1980-01-01

    The application of RF circuit design principles to high-frequency power converters is described. Compared to conventional converter design, emphasis is placed on obtaining sinusoidal-type waveforms (instead of rectangular-type waveforms) to minimize device switching time requirements and alleviate transforming requirements. A 25-W 48-V to 5-V dc-to-dc converter design using a 5-MHz switching frequency is presented illustrating these principles, using a Class

  19. Applications and benefits of catalytic converter thermal management

    Microsoft Academic Search

    Steven D. Burch; Matthew A. Keyser; Chris P. Colucci; Thomas F. Potter; David K. Benson; J. P. Biel

    1996-01-01

    A catalytic converter thermal management system (TMS) using variable-conductance vacuum insulation and phase-change thermal storage can maintain the converter temperature above its operating temperature for many hours, allowing most trips to begin with minimal ``cold-start`` emissions. The latest converter TMS prototype was tested on a Ford Taurus (3.0 liter flex-fuel engine) at Southwest Research Institute. Following a 24-hour soak, the

  20. Large-signal stability analysis of PWM converters

    SciTech Connect

    Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering

    1995-12-31

    Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.

  1. A Novel Converter System for Fuel Cell Distributed Energy Generation

    Microsoft Academic Search

    R. Attanasio; M. Cacciato; A. Consoli; G. Scarcella; A. Testa; F. Gennaro

    2005-01-01

    To interface the fuel cells (FCs) to grid\\/loads a DC\\/AC energy conversion system is required with the capability to act as an energy buffer for matching generator-load dynamics. A new power converter design is proposed based on cascade connection of a DC\\/DC and a DC\\/AC converter. The DC\\/DC converter has to control the FC current ripple and regulate the power

  2. A multiphase PWM converter chip for the advanced microprocessors

    Microsoft Academic Search

    Guoyong Guo; Bingxue Shi

    2005-01-01

    The DC–DC converter is a fundamental component of the personal computer motherboard and occupies a number of communication areas. To solve the problem of meeting the power supply requirements of the new microprocessor that requires 40–100A current, lower voltage and higher regulation performance during current transients, a multiphase pulse-width modulator (PWM) converter is designed. Multiphase converters, by distributing the power

  3. Zero-voltage switching technique in DC\\/DC converters

    Microsoft Academic Search

    Kwang-Hwa Liu; F. C. Y. Lee

    1990-01-01

    A novel resonant switch operating under the principle of zero-voltage switching is presented. The basic configurations of the voltage-mode resonant switches are presented. The circuit's operating principles are described using a voltage-mode quasi-resonant boost converter. DC analysis of the converter is carried out. A new family of voltage-mode quasi-resonant converters are derived, and several members of this family are presented.

  4. Noninterlaced-To-Interlaced Television-Scan Converter

    NASA Technical Reports Server (NTRS)

    Morales, Sergio

    1988-01-01

    Computer text and ordinary images displayed together without text jitter. Scan converter enables superposition of alphanumerical text generated by computer-driven video generator on National Television System Committee (NTSC) standard interlaced-scan image. Made of commercially available integrated circuits and operates in conjunction with NTSC synchronizing-signal generator. Standard television picture transmitted in two interlaced fields. Without scan converter, text image moves up and down by one line as fields change. With scan converter, text image stands still.

  5. Determinants of Angiotensin II Generation During Converting Enzyme Inhibition

    Microsoft Academic Search

    Lucienne Juillerat; Jurg Nussberger; Vincent Mooser; Yves Christen; Bernard Waeber; Peter Graf; Hans R. Brunner

    2010-01-01

    The reaction of the renin-angiotensin system to acute angiotensin converting enzyme inhibition was investigated in a single-blind, crossover study in nine normal volunteers receiving two out of three regimens in random order the new converting enzyme inhibitor benazepril (20 mg once or 5 mg four times at 6-hour intervals) or enalapril (20 mg). Plasma converting enzyme activity, drug levels, angiotensin

  6. Systematic Design of High-Performance Data Converters

    Microsoft Academic Search

    Georges Gielen; Jan Vandenbussche; Geert Van der Plas; Walter Daems; Anne Van den Bosch; Michiel Steyaert; Willy Sansen

    A systematic design methodology for high-speed high-accuracy D\\/A converters has been demonstrated. The methodology covers\\u000a the complete design flow starting from the specification phase of the converter as macrocell in a larger system down to a\\u000a fully synthesized and laid out implementation followed by a verification of the entire system with a behavioral model extracted\\u000a from the actual designed converter.

  7. 10MW GTO converter for battery peaking service

    Microsoft Academic Search

    L. H. Walker

    1990-01-01

    A bidirectional 18-pulse voltage-source converter utilizing gate-turnoff thyristors (GTOs) is described. The converter, which is rated 10 MVA, was placed in service in early 1988 to connect an energy storage battery to a utility grid. The converter is rated and controlled to operate in all four quadrants (discharge, charge, leading VAr, or lagging VAr) at the full 10 MVA rating.

  8. Reliability comparison of matrix and other converter topologies

    Microsoft Academic Search

    M. Aten; G. Towers; C. Whitley; P. Wheeler; J. Clare; K. Bradley

    2006-01-01

    Several rectifier-inverter and matrix converter topologies suitable for aerospace applications are compared, and their reliability is predicted. The military handbook MIL-HDBK-217F guidelines have been used to predictreliability. The matrix converter has several attractive features for aerospace applications such as potential size and weight savings. Although the matrix converter has a higher number of semiconductor switches, they are subjected to a

  9. Novel Three-Phase AC–AC Sparse Matrix Converters

    Microsoft Academic Search

    Johann W. Kolar; Frank Schafmeister; Simon D. Round; Hans Ertl

    2007-01-01

    A novel three-phase ac-ac sparse matrix converter having no energy storage elements and employing only 15 IGBTs, as opposed to 18 IGBTs of a functionally equivalent conventional ac-ac matrix converter, is proposed. It is shown that the realization effort could be further reduced to only nine IGBTs in an ultra sparse matrix converter (USMC) in the case where only unidirectional

  10. Matrix converter topologies with reduced number of switches

    Microsoft Academic Search

    Lixiang Wei; T.A. Lipo; Ho Chan

    2002-01-01

    A direct AC-to-AC converter commonly termed a matrix converter has a simple structure and many attractive features. However, the complexity of its conventional PWM strategy is prone to commutation failure, which is a factor that keeps it from being utilized in industry. This paper focuses on several alternative dual-bridge matrix topologies which do not possess this problem. First, these converters

  11. A matrix converter based micro-turbine distributed generation system

    Microsoft Academic Search

    Hassan Nikkhajoei; M. Reza Iravani

    2005-01-01

    This paper investigates the use of an AC-AC matrix converter, as an alternative to AC-DC-AC converter system, to interface a high-speed micro-turbine generator (MTG) to a utility grid as a distributed generation unit. A new switching strategy and a control mechanism for the converter are presented. Based on time-domain simulations in the PSCAD\\/EMTDC environment, the dynamic behavior of a micro-turbine

  12. Power Converters Maximize Outputs Of Solar Cell Strings

    NASA Technical Reports Server (NTRS)

    Frederick, Martin E.; Jermakian, Joel B.

    1993-01-01

    Microprocessor-controlled dc-to-dc power converters devised to maximize power transferred from solar photovoltaic strings to storage batteries and other electrical loads. Converters help in utilizing large solar photovoltaic arrays most effectively with respect to cost, size, and weight. Main points of invention are: single controller used to control and optimize any number of "dumb" tracker units and strings independently; power maximized out of converters; and controller in system is microprocessor.

  13. Novel vortex generator and mode converter for electron beams.

    PubMed

    Schattschneider, P; Stöger-Pollach, M; Verbeeck, J

    2012-08-24

    A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG(10) and HG(01) modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge m=±1. This combination serves as a generator of electron vortex beams of high brilliance. PMID:23002749

  14. A novel vortex generator and mode converter for electrons

    E-print Network

    Peter Schattschneider; Michael Stoeger-Pollach; Johan Verbeeck

    2012-05-10

    A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with topological charge $m=\\pm 1$ into beams closely resembling Hermite-Gaussian HG$_{10}$ and HG$_{01}$ modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge $m=\\pm 1$. This combination serves as a generator of electron vortex beams of high brilliance.

  15. DC overvoltage control during loss of converter in multiterminal voltage-source converter-based HVDC (M-VSC-HVDC)

    Microsoft Academic Search

    Weixing Lu; Boon-Teck Ooi

    2003-01-01

    Security requires that a system continues to function even when any one subsystem fails. A multiterminal HVDC system consists of N voltage-source converters (VSCs) exchanging power through a DC network. When any one converter is lost, before the surviving (N-1) converters have time to re-establish a new power balance, the excess DC power can produce voltage spikes which are destructive

  16. High-power converters for space applications

    NASA Technical Reports Server (NTRS)

    Park, J. N.; Cooper, Randy

    1991-01-01

    Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

  17. Durability of ceramic catalytic converters for motorcycles

    SciTech Connect

    Reddy, K.P.; Scott, P.L. [Corning, Inc., NY (United States); Hwang, H.S.; Mooney, J.J. [Engelhard Corp., Edison, NJ (United States)

    1995-12-31

    Motorcycle exhaust emission standards throughout the world are becoming more stringent. Emission control systems utilizing the catalytic converter are already in production in Taiwan for 2-stroke engine motorcycles. Catalysts designed for 2-stroke engines encounter a more severe exhaust environment than do those designed for 4-stroke engines. The two aspects of increased severity are the higher temperatures and higher stresses due to engine vibrations. Precious metal catalysts have been designed to operate in the thermal environment of 2-stroke engines and such catalysts have been successfully applied to both metal and ceramic substrates. However, until now, only the metal substrate catalysts have been utilized in motorcycle application. Ceramic based catalysts have not been considered because the mounting material that holds the catalyst substrate in place did not have enough durability to withstand the thermal/vibrational forces encountered in 2-stroke engine exhaust. Ceramic substrates have many advantages such as superior high temperature strength, which is especially important for the 2-stroke engine application, flexibility in cell shape and density, and lower cost. To realize these benefits, efforts were made in this study to develop better mounting systems. The results of this effort indicate that the durability requirements of 2-stroke engine can be met with the ceramic catalyst substrates if the improved mounting designs reported in the present study are employed.

  18. Optimization of Aperiodic Waveguide Mode Converters

    SciTech Connect

    Burke, G J; White, D A; Thompson, C A

    2004-12-09

    Previous studies by Haq, Webb and others have demonstrated the design of aperiodic waveguide structures to act as filters and mode converters. These aperiodic structures have been shown to yield high efficiency mode conversion or filtering in lengths considerably shorter than structures using gradual transitions and periodic perturbations. The design method developed by Haq and others has used mode-matching models for the irregular, stepped waveguides coupled with computer optimization to achieve the design goal using a Matlab optimization routine. Similar designs are described here, using a mode matching code written in Fortran and with optimization accomplished with the downhill simplex method with simulated annealing using an algorithm from the book Numerical Recipes in Fortran. Where Haq et al. looked mainly for waveguide shapes with relatively wide cavities, we have sought lower profile designs. It is found that lower profiles can meet the design goals and result in a structure with lower Q. In any case, there appear to be very many possible configurations for a given mode conversion goal, to the point that it is unlikely to find the same design twice. Tolerance analysis was carried out for the designs to show edge sensitivity and Monte Carlo degradation rate. The mode matching code and mode conversion designs were validated by comparison with FDTD solutions for the discontinuous waveguides.

  19. Converting sensitive waste into cleaner energy

    SciTech Connect

    Schriner, D.; Skinner, R.

    1997-10-01

    The destruction of sensitive unclassified information (SUI) has always been expensive due to the need for special controls to ensure its protection from disclosure to unauthorized persons. The sensitive documents were shredded, buried at the landfill, or sent to a recycling company. The Department of Energy (DOE) Idaho National Engineering and Environmental Laboratory (INEEL), operated by Lockheed Martin Idaho Technologies Company (LMITCO), has created an innovative method to dispose of its sensitive unclassified paper waste which has security, economic, and environmental benefits. A new cubing facility at the INEEL converts office and industrial waste into compact cubes which are then combined with coal and burned as a source of heat and process steam to run the Idaho Chemical Processing Plant (ICPP) facility. The process-engineered fuel, consisting of 25% cubes and 75% coal, bums cleaner than coal with lower emissions of sulfur dioxide and nitrogen oxides. The alternative fuel also reduces fuel costs, eliminates paying a recycling company, reduces the expense of landfill disposal, increases the life of the landfill, and provides energy to operate a large facility. The Operations Security (OPSEC) team capitalized on this waste to energy technology by recommending that the large quantities of sensitive information (documents) generated at the INEEL be disposed of in this manner. In addition to the economic and environmental benefits, this disposal method minimizes the vulnerabilities of SUI from disclosure to unauthorized personnel. The {open_quotes}cuber{close_quotes} technology has potential application in government and industry for protection of SUI.

  20. Novel modulation method for multidirectional matrix converter.

    PubMed

    Toosi, Saman; Misron, Norhisam; Hanamoto, Tsuyoshi; Bin Aris, Ishak; Radzi, Mohd Amran Mohd; Yamada, Hiroaki

    2014-01-01

    This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation. PMID:25298969

  1. Phosphorus Removal Characteristics in Hydroxyapatite Crystallization Using Converter Slag

    Microsoft Academic Search

    EUNG-HO KIM; HWAN-KOOK HWANG; SOO-BIN YIM

    2006-01-01

    This study was performed to investigate the phosphorus removal characteristics in hydroxyapatite (HAP) crystallization using converter slag as a seed crystal and the usefulness of a slag column reactor system. The effects of alkalinity, and the isomorphic-substitutable presence of ionic magnesium, fluoride, and iron on HAP crystallization seeded with converter slag, were examined using a batch reactor system. The phosphorus

  2. Emissions reductions using hydrogen from plasmatron fuel converters

    Microsoft Academic Search

    L Bromberg; D. R Cohn; A Rabinovich; J Heywood

    2001-01-01

    Improvements in internal combustion engine and aftertreatment technologies are needed to meet future environmental quality goals. Systems using recently developed compact plasmatron fuel converters in conjunction with state-of-the-art engines and aftertreatment catalysts could provide new opportunities for obtaining substantial emissions reductions. Plasmatron fuel converters provide a rapid response, compact means to transform a wide range of hydrocarbon fuels (including gasoline,

  3. Digitally Controlled DC-DC Converter for RF Power Amplifier

    Microsoft Academic Search

    Vahid Yousefzadeh; Narisi Wang

    2006-01-01

    This paper describes design and implementation of a digitally controlled DC-DC converter that provides a dynamically adjustable supply voltage for an RF power amplifier (RFPA). The techniques employed in the design include a combination of constant-frequency continuous conduction mode and a variable- frequency discontinuous conduction mode to achieve very high converter efficiency over a wide range of output power levels.

  4. Tracking power converter for supply modulation of RF power amplifiers

    Microsoft Academic Search

    P. Midya; K. Haddad; L. Connell; S. Bergstedt; B. Roeckner

    2001-01-01

    This paper describes a tracking power converter and the controller IC for its implementation. The tracking power converter is used for supply modulation of a linear RF power amplifier. Supply modulation improves RF power amplifier efficiency for variable envelope RF signals. This system maximizes tracking bandwidth (~160 kHz), ripple suppression (~70 dB) and power conversion efficiency (~92%) with a relatively

  5. Converting enzyme inhibition and progressive glomerulosclerosis in the rat

    Microsoft Academic Search

    Joke J B Beukers; Annemieke van der Wal; Philip J Hoedemaeker; Jan J Weening

    1987-01-01

    Converting enzyme inhibition and progressive glomerulosclerosis in the rat. The effect of converting enzyme inhibition (CEI) by captopril (CAP, 500 mg\\/liter drinking water) on the development and progression of glomerulosclerosis (GS) was studied in six groups of male unine-phrectomized (UN) Wistar rats. In group A, treated with CAP for four to five weeks after UN, a reduction in systolic blood

  6. Program Converts VAX Floating-Point Data To UNIX

    NASA Technical Reports Server (NTRS)

    Alves, Marcos; Chapman, Bruce; Chu, Eugene

    1996-01-01

    VAX Floating Point to Host Floating Point Conversion (VAXFC) software converts non-ASCII files to unformatted floating-point representation of UNIX machine. This is done by reading bytes bit by bit, converting them to floating-point numbers, then writing results to another file. Useful when data files created by VAX computer must be used on other machines. Written in C language.

  7. Interleaved Bidirectional DC-DC Converter for Automotive Electric Systems

    Microsoft Academic Search

    Dong-Hyun Ha; Nam-Ju Park; Kui-Jun Lee; Dong-Gyu Lee; Dong-Seok Hyun

    2008-01-01

    In this paper, interleaved bidirectional DC-DC converter with ZVT cell using a single resonant inductor in continuous conduction mode is proposed. The proposed interleaved bidirectional DC-DC converter has advantages such as a simple circuit, ZVS during wide load range and minimization of current injection effect by using dual current injection time. Also, it is possible to reduce diode drop voltage

  8. Wave energy converters and their impact on power systems

    Microsoft Academic Search

    Henk Polinder; Mattia Scuotto

    2005-01-01

    The objective of this paper is to give an introduction into ocean wave energy converters and their impact on power systems. The potential of wave energy is very large. There are a lot of different methods and systems for converting this power into electrical power, such as oscillating water columns, hinged contour devices as the Pelamis, overtopping devices as the

  9. Prototype testing of the wave energy converter wave dragon

    Microsoft Academic Search

    Jens Peter Kofoed; Peter Frigaard; Erik Friis-Madsen; Hans Chr. Sørensen

    2006-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power.In the period from 1998 to 2001 extensive wave tank testing on a scale model

  10. High power DC-to-DC converter for supercapacitors

    Microsoft Academic Search

    B. J. Arnet; L. P. Haines

    2001-01-01

    The purpose of this paper is to present Solectria's approach to the design and realization of a high power, nonisolated DC-to-DC power converter for supercapacitors. The study focuses on supercapacitor specific design rules and on how to integrate the unit into a system with other energy storage devices and converters. Two applications are presented to illustrate the validity of the

  11. Busbar design considerations for high power IGBT converters

    Microsoft Academic Search

    H. J. Beukes; J. H. R. Enslin; R. Spee

    1997-01-01

    This paper addresses an important issue in the design and synthesis of high power IGBT converters, i.e. the layout and design of connection busbars. Parasitic inductance, caused by the physical distance current has to flow from the storage capacitors to the static switches and back, is the major constraint in developing a bus structure. This leads to nonideal converter operation,

  12. Digital parallel-to-series pulse-train converter

    NASA Technical Reports Server (NTRS)

    Hussey, J.

    1971-01-01

    Circuit converts number represented as two level signal on n-bit lines to series of pulses on one of two lines, depending on sign of number. Converter accepts parallel binary input data and produces number of output pulses equal to number represented by input data.

  13. Imaging of converted-wave ocean-bottom seismic data

    Microsoft Academic Search

    Daniel Alejandro Rosales Roche

    2007-01-01

    Converted-wave data can be imaged with several methodologies. The transformation of data into the image space, is defined by an imaging operator, the simplest of which is normal moveout correction plus stack. Most of the converted-wave processing is carried out in the data domain, that is in time, data midpoint location, and data offset, this processing is not ideal for

  14. Advanced catalytic converter system for natural gas powered diesel engines

    Microsoft Academic Search

    Vadim O. Strots; Grigorii A. Bunimovich; Yurii Sh. Matros; Ming Zheng; Edward A. Mirosh

    1998-01-01

    The paper discusses the development of catalytic converter for aftertreatment of exhaust gas from diesel engines powered with natural gas. The converter, operated with periodical reversals of the flow, ensures destruction of CO and hydrocarbons, including methane. Both computer simulation and engine testing results are presented.

  15. The potential and prob-lems of converting forest and

    E-print Network

    Exxon-Mobil recently has decided to invest heavily in making fuel from algae because it can be grown potential for being converted into fuel, said Dr. Richard Vlosky, director of the Louisiana Forest Products potential for making fuels from wood biomass. Chevron and Weyerhaeuser have formed a partnership to convert

  16. Paralleled LCsCp resonant converters for spark erosion applications

    Microsoft Academic Search

    Rosario Casanueva; Francisco J. Azcondo; Christian Brañas; Salvador Bracho

    2004-01-01

    In this paper, the analysis, design, and experimental results of the parallel connection of LCsCp resonant converters for a spark erosion power supply are presented. To increase the power of the spark erosion power supply, synchronous (same frequency and phase) and interleaved (same frequency and phase shift) parallel connection of N LCSCP resonant converters are proposed. In this way, the

  17. Noise Source Lumped Circuit Modeling and Identification for Power Converters

    Microsoft Academic Search

    Jin Meng; Weiming Ma; Qijun Pan; Zhihua Zhao; Lei Zhang

    2006-01-01

    In this paper, a general lumped circuit modeling method is proposed to describe the conducted electromagnetic interference (EMI) coupling mechanism for the switching power converters. The EMI characteristics of the converters can be analytically deduced from a circuit theoretical viewpoint. The shunt and series impedance insertion method is introduced to identify the differential-mode (DM) and common-mode (CM) noise impedances and

  18. Aircraft power system harmonics involving single-phase PFC converters

    Microsoft Academic Search

    Jian Sun; Min Chen; KAMIAR J. KARIMI

    2008-01-01

    AC-DC converters with active power factor correction (PFC) are replacing uncontrolled diode rectification circuits on commercial jet airplanes in order to meet harmonic distortion limits imposed by new airborne electrical system power quality standards. The high line frequency of airborne AC power systems presents a major challenge for the design of PFC converters capable of meeting these standards. This paper

  19. Multiterminal DC transmission system based on modular multilevel converter

    Microsoft Academic Search

    Grain P Adam; Olimpo Anaya-Lara; Graeme Burt

    2009-01-01

    A multi-terminal DC (MTDC) transmission system based on an innovative modular multilevel converter (MMC) is presented as a feasible approach to address the concerns regarding reliability and fault ride through capability of multi-terminal dc systems. Furthermore, MTDC using MMC may reduce construction costs and power losses in the converter stations. To demonstrate control flexibility, improved reliability and DC fault ride

  20. Wavelength Converters in Dynamically-Reconfigurable WDM Networks

    Microsoft Academic Search

    Jennifer M. Yates; Michael P. Rumsewicz; Jonathan P. R. Lacey

    1999-01-01

    In simple wavelength-division multiplexed (WDM) networks, a connection must be established along a route using a common wavelength on all of the links along the route. This constraint may be removed by the introduction of wavelength converters, which are devices which take the data modulated on an input wavelength and transfer it to a different output wavelength. Wavelength converters thus

  1. Thermal-To-Electric Converter With Greater Power Density

    NASA Technical Reports Server (NTRS)

    Williams, Roger M.; Suitor, Jerry W.; Jeffries-Nakamura, Barbara; Underwood, Mark L.; Ryan, Margaret A.; O'Connor, Dennis

    1992-01-01

    Proposed design for alkali-metal thermal-to-electric converter (AMTEC) incorporates refinements to increase power density and reduce input temperature below typical prior design. Converter has compact, planar configuration. Cells stacked densely with remote condenser for thermal efficiency and high power density. Either liquid- or vapor-fed cells utilized. Heat fed-in at lower temperature.

  2. Effect of catalytic converter on rotary combustion engine exhaust

    Microsoft Academic Search

    K. C. Tsao; O. K. Foo; Y. Y. Tom

    1974-01-01

    The effect of a monolithic catalytic converter on rotary combustion engine exhaust was investigated at various engine operating conditions. The concentrations of hydrocarbons and carbon monoxide were determined by flame ionization detection and non-dispersive infrared methods. The percentages of reduction of hydrocarbons and CO concentrations were affected by the inlet gas temperature of the monolithic converter, the loading, the air-fuel

  3. Skip cycle modulation in switching DC-DC converter

    Microsoft Academic Search

    Ping Luo; Luyang Luo; Zhaoji Li; Jian Yang; Guangiv Chen

    2002-01-01

    A novel control mode named SCM (skip cycle modulation) in switching DC-DC converter is developed and analyzed in this paper. The principles and the characteristics of SCM are described. Compared with PWM and PFM control modes, the response speed of DC-DC converter under SCM control mode is faster, the efficiency of the system with low loads is higher, and the

  4. Soft switched high frequency ac-link converter

    E-print Network

    Balakrishnan, Anand Kumar

    2009-05-15

    , in contrast with the diode rectifler based PWM-VSI separated by the dc-link capacitor. This aspect makes the modulation control of the matrix converter quite difierent and com- plicated, compared to other indirect ac-ac power converters. As a result...

  5. Reduction of proteinuria by angiotensin converting enzyme inhibition

    Microsoft Academic Search

    Jan E Heeg; Paul E de Jong; Gjalt K van der Hem; Dick de Zeeuw

    1987-01-01

    Reduction of proteinuria by angiotensin converting enzyme inhibition. The effects of the angiotensin converting enzyme (ACE) inhibitor lisinopril on blood pressure, proteinuria and renal hemodynamics were evaluated in 13 patients with renal disease of different origin. A comparison was made with the effects of conventional antihypertensive therapy. Both drug regimens significantly lowered blood pressure, while only after 12 weeks of

  6. Top2maya A Tool for Converting 2D Topographical

    E-print Network

    Illinois at Urbana-Champaign, University of

    Top2maya ­ A Tool for Converting 2D Topographical Maps to 3D Models Rob Gillespie Student techreports@itg.uiuc.edu http://www.itg.uiuc.edu #12;Top2maya ­ A Tool for Converting 2D Topographical Maps@itg.uiuc.edu Top2maya is a program written in MEL script which changes 2D topographical maps into three

  7. Top2maya A Tool for Converting 2D Topographical

    E-print Network

    Illinois at Urbana-Champaign, University of

    Top2maya ­ A Tool for Converting 2D Topographical Maps to 3D Models Rob Gillespie, Consultant 61801 techreports@itg.uiuc.edu http://www.itg.uiuc.edu #12;Top2maya ­ A Tool for Converting 2D top2maya Top2maya is a program written in MEL script which changes 2D topographical maps into three

  8. MATHEMATICAL ANALYSIS OF A WAVE ENERGY CONVERTER ARNAUD ROUGIREL

    E-print Network

    Paris-Sud XI, Université de

    MATHEMATICAL ANALYSIS OF A WAVE ENERGY CONVERTER MODEL ARNAUD ROUGIREL Abstract. In a context where energy converter without mass modulation. 1. Introduction In the recent years, sustainable development sustainable development should be a priority, Orazov et al. have proposed in 2010, an excitation scheme

  9. A boost converter associated with a new nondissipative snubber

    Microsoft Academic Search

    Luiz H. S. C. Barreto; Adriano A. Pereira; Valdeir J. Farias; Luiz C. de Freitas; Jolo B. Vieira Jr

    1998-01-01

    This paper presents a boost converter with a nondissipative snubber which provides a soft switching converter operation. This approach allows the main switch to work in a ZVS way and the auxiliary switch to work in a ZCS way. The nondissipative snubber is composed by two capacitors (resonant capacitors), one inductor (resonant inductor), one switch (auxiliary switch) and two diodes,

  10. A voltage resonant single ended converter with auxiliary switch

    Microsoft Academic Search

    Toshihiro Onodera; Toshiba Komukai

    1998-01-01

    This paper describes a new single-ended voltage resonance power converter without changing the period of a main switch S1 and with changing the conduction period. The power converter is composed of a parallel LC-resonance circuit and an auxiliary switch S2. New topologies for the auxiliary switch S2 is derived from a half-cycle delay concept

  11. A converter-type magnetometer using amorphous ribbon or wire

    Microsoft Academic Search

    Marek Z. Kozak; Eugeniusz Misiuk; Waldemar Kwiatkowski

    1991-01-01

    The accurate and quick-response magnetometer presented here is composed of a resonant circuit with an amorphous core, an operational amplifier, and a voltage-current converter. Nonmagnetostrictive amorphous ribbons or wires are used in the straight form for sensing strength and direction of the dc magnetic field. The range having good linearity strongly depends on the converter current and the demagnetizing field

  12. An Advanced Turbo-Brayton Converter for Radioisotope Power Systems

    Microsoft Academic Search

    Mark V. Zagarola; Michael G. Izenson; Jeffrey J. Breedlove; George M. O'Connor; Andrew C. Ketchum; Richard L. Jetley; James K. Simons

    2005-01-01

    Past work has shown that Brayton power converters are an attractive option for high power, long-duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo-Brayton converter under NASA's Prometheus Program.

  13. Analysis of a Flying Capacitor Converter: A Switched Systems Approach

    E-print Network

    Margaliot, Michael

    Analysis of a Flying Capacitor Converter: A Switched Systems Approach Alex Ruderman, Boris Reznikov, and Michael Margaliot Abstract Flying capacitor converters (FCCs) attract considerable interest because of a certain matrix. We also show that it is possible to rigorously analyze properties such as the capacitor

  14. Stability analysis of electrical drives fed by matrix converters

    Microsoft Academic Search

    D. Casadei; G. Serra; A. Tani; L. Zarri

    2002-01-01

    Input filters are usually adopted in electrical drives in order to improve the input current quality and to reduce the input voltage distortion. These filters; can determine instabilities, depending on the converter topology and drive control strategy. In this paper the stability of an electrical drive fed by a three-phase to three-phase matrix converter is analyzed considering two different input

  15. Sequential color video to parallel color video converter

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The engineering design, development, breadboard fabrication, test, and delivery of a breadboard field sequential color video to parallel color video converter is described. The converter was designed for use onboard a manned space vehicle to eliminate a flickering TV display picture and to reduce the weight and bulk of previous ground conversion systems.

  16. Direct-current converter for gas-discharge lamps

    NASA Technical Reports Server (NTRS)

    Lutus, P.

    1980-01-01

    Metal/halide and similar gas-discharge lamps are powered from low-voltage dc source using small efficient converter. Converter is useful whenever 60-cycle ac power is not available or where space and weight allocations are limited. Possible applications are offshore platforms, mobile homes, and emergency lighting. Design innovations give supply high reliability and efficiency up to 75 percent.

  17. Microscopic and flow cytometric semen assessment of Dutch AI-bucks: effect of semen processing procedures and their correlation to fertility.

    PubMed

    Peterson, K; Kappen, M A P M; Ursem, P J F; Nöthling, J O; Colenbrander, B; Gadella, B M

    2007-03-01

    This study was done to determine the effects of processing techniques on the quality of semen from Dutch AI-bucks with the view on improving pregnancy rates after artificial insemination (AI) with liquid or frozen-thawed semen. Motility of spermatozoa was estimated under a microscope whereas the percentage live spermatozoa and the percentage live spermatozoa with intact acrosomes were determined by means of flow cytometry. Aspects of semen processing that were investigated are storage temperature of liquid semen (i), the effect of glycerol on liquid-stored semen (ii), removal of seminal plasma (iii) and type of extender (iv). The correlation between semen quality and fertility rates in inseminated does was also investigated. The percentage motile spermatozoa in semen stored in liquid form for 72 h progressively declined over time, irrespective of whether storage occurred at 4 or 18 degrees C. The percentage motile spermatozoa in semen stored at 18 degrees C was similar to that in semen stored at 4 degrees C if stored for 24 h but lower if stored for 48 h. Goats differ in the sensitivity of their spermatozoa to the deleterious effects of glycerol. Neither the removal of seminal plasma nor the type of extender had any effect on semen quality before freezing but semen frozen in a Tris-citric acid-glucose (TCG) buffer with egg yolk without removal of the seminal plasma had better quality after thawing than semen frozen in another diluent or after removal of seminal plasma. Remarkably no significant correlation between fertility and membrane integrity of spermatozoa could be found. Thus, although integrity assays for spermatozoa are useful to asses resistance to semen handling, the validity of these assays for predicting fertility is questioned. PMID:17126897

  18. Tertiary side resonant DC/DC converter with integrated magnetics

    SciTech Connect

    Jain, P. [Concordia Univ., Montreal, Quebec (Canada)] [Concordia Univ., Montreal, Quebec (Canada); Jain, P.; Quaicoe, J. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada)] [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada)

    1996-09-01

    This paper presents a constant frequency tertiary side resonant dc/dc converter topology. The proposed converter topology gives the opportunity to integrate all the resonant inductors with the output transformer and provides greater flexibility in selecting the resonant capacitors. The harmonic equivalent circuit model and frequency domain analysis, which incorporates the effect of the leakage inductance of the high frequency transformer are presented. Steady state characteristics curves are presented to describe the effect of the leakage inductance and resonant circuit parameters on the performance of the converter. It is shown that with a tuned parallel resonant circuit on the tertiary winding the converter can be operated at higher frequencies. Finally, the experimental results show a higher than 80% efficiency for a 500 W, 48V to 5V dc/dc converter operating at 128 kHz.

  19. Low cost cylindrical converter for measuring lead efficiency

    NASA Technical Reports Server (NTRS)

    Hatch, G. L.; Nakata, L.; Britt, E. J.

    1979-01-01

    A low cost cylindrical thermionic converter has been designed, fabricated, and tested for use in a NASA-JPL program to directly measure converter lead efficiencies using various electrode materials and surfaces. Efficiency measurements are made using input emitter heater power, output power at the leads, and calculated values of the parasitic losses that would not be present in the application configuration. This information can be used to predict the performance characteristics of the advanced converters currently under development. A series of five converters has been tested. Both structured and smooth molybdenum collectors have been used. Emitters included smooth molybdenum, smooth rhenium, and microstructured rhenium. Cesium pressure families of current-voltage curves are presented for emitter temperatures of 1600, 1700, and 1800 K, along with measured efficiencies as a function of converter current densities for each temperature.

  20. Magnet Technology for Power Converters: Nanocomposite Magnet Technology for High Frequency MW-Scale Power Converters

    SciTech Connect

    None

    2012-02-27

    Solar ADEPT Project: CMU is developing a new nanoscale magnetic material that will reduce the size, weight, and cost of utility-scale PV solar power conversion systems that connect directly to the grid. Power converters are required to turn the energy that solar power systems create into useable energy for the grid. The power conversion systems made with CMU’s nanoscale magnetic material have the potential to be 150 times lighter and significantly smaller than conventional power conversion systems that produce similar amounts of power.

  1. A novel soft-switching grid-connected PV inverter and its implementation

    Microsoft Academic Search

    Minjie Chen; Xutao Lee; Yoshihara Tsutomu

    2011-01-01

    This paper proposes a novel soft-switching PV inverter formed by a ZVT-PWM boost converter, a ZVS-ZCS-PWM buck converter and a low frequency full-bridge inverter. The ZVT-PWM boost converter maintains the dc-bus voltage and provides an auxiliary current source for the soft-switching cell of the buck converter. The buck converter consists of a main switch and an auxiliary switch, with ZVS

  2. Proportional step size tracking analog-to-digital converter.

    PubMed

    Last, T A

    1980-03-01

    A new type of tracking analog-to-digital converter, which is capable of responding quickly to step changes in the input voltage, has been developed. The device produces an error signal which indicates the difference between the converter's state and the input signal level. This error signal is used to modify the converter's slew rate in such a way as to optimize convergence back to the tracking condition (i.e., the condition at which the converter's state accurately tracks the input signal). This error signal is also used to generate an accuracy code which indicates if the converter is accurately tracking the input signal, or if the converter is out of track, how many bits of the encoded data are actually significant. An eight-bit transient recorder was developed using the converter described above. The instrument was found to be capable of recording data at rates up to 10(6) points/s, and was observed to respond to step voltage changes within eight datum points. PMID:18647070

  3. Torgue converter lockup clutch control for an automatic transmission

    SciTech Connect

    Crandall, S.R.; Droste, T.A.; Rosen, S.D.

    1989-10-31

    This patent describes a converter lockup clutch system controlling an automatic transmission torque converter having an impeller adapted for driveable connection to an engine and a turbine hydrokinetically driveable to the impeller. It comprises: a torque converter clutch for alternately locking and releasing the impeller and turbine, having a first passage carrying converter release pressure to unlock the clutch and a second passage carrying apply pressure to lock the clutch; a source of line pressure, manual valve means for connecting the source of line pressure to an outlet when a low gear ratio is selected manually by a vehicle operator; first control means for producing first control pressure states representing commands to release and to apply the torque converter; and a converter clutch control valve means communicating with the outlet; the first control means and the source of line pressure when the first control means produce the converter apply pressure state, and for connecting the first passage to the source of line pressure when the low gear ratio is selected regardless of the pressure state produced by the first control means.

  4. Study of switching transients in high frequency converters

    NASA Technical Reports Server (NTRS)

    Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

    1993-01-01

    As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is evaluated.

  5. Architecture for a High-to-Medium-Voltage Power Converter

    NASA Technical Reports Server (NTRS)

    Vorpenian, Vatche

    2008-01-01

    A power converter now undergoing development is required to operate at a DC input potential ranging between 5.5 and 10 kV and a DC output potential of 400 V at a current up to 25 A. This power converter is also required to be sufficiently compact and reliable to fit and operate within the confines of a high-pressure case to be lowered to several miles (approx.5 km) below the surface of the ocean. The architecture chosen to satisfy these requirements calls for a series/ parallel arrangement of 48 high-frequency, pulse-width-modulation (PWM), transformer-isolation DC-to-DC power converter blocks. The input sides of the converter blocks would be connected in series so that the input potential would be divided among them, each of them being exposed to an input potential of no more than 10 kV/48 . 210 V. The series connection of inputs would also enforce a requirement that all the converter blocks operate at the same input current. The outputs of the converter blocks would be connected in a matrix comprising 6 parallel legs, each leg being a cascade of eight outputs wired in series (see figure). All the converter blocks would be identical within the tolerances of the values of their components. A single voltage feedback loop would regulate the output potential. All the converter blocks would be driven by the same PWM waveform generated by this feedback loop. The power transformer of each converter block would have a unity turns ratio and would be capable of withstanding as much as 10 kVDC between its primary and secondary windings. (Although, in general, the turns ratio could be different from unity, the simplest construction for minimizing leakage and maximizing breakdown voltage is attained at a turns ratio of unity.)

  6. DC-DC Converter for Avalanche Photodetector DC-DC converter to generate above 10 V from 2.5 V supply voltage.

    E-print Network

    Choi, Woo-Young

    Amplifier CDR Reverse Bias Voltage Boosting Circuit PWM Circuit Schematic Avalanche Photodetector SupplyDC-DC Converter for Avalanche Photodetector DC-DC converter to generate above 10 V from 2.5 V supply voltage. DC-DC Converter High-Speed Circuits and Systems Lab 1 DC-DC Converter TIA Limiting

  7. Large bandwidth mode order converter by differential waveguides.

    PubMed

    Oner, B B; Üstün, K; Kurt, H; Okyay, A K; Turhan-Sayan, G

    2015-02-01

    In this article, we propose a large bandwidth mode-order converter design by dielectric waveguides with equal lengths but different cross-sectional areas. The efficient conversion between even and odd modes is verified by inducing required phase difference between the equal length waveguides of different widths. Y-junctions are composed of both tapered mode splitter and combiner to connect mono-mode waveguide to multi-mode waveguide. The converted mode profiles at the output port show that the device operates successfully at designed wavelengths with wide bandwidth. This study provides a novel technique to implement compact mode order converters and direction selective/sensitive photonic structures. PMID:25836177

  8. Study of volume versus frequency for soft switching IGBT converters

    NASA Astrophysics Data System (ADS)

    Masserant, Brian J.; Beans, E. William; Stuart, Thomas A.

    1995-01-01

    Earlier references have described a new soft switched ZVS/ZCS (zero voltage switching, zero current switching) converter for IGBTs that allows operation above 20 kHz. Although frequencies above 20 kHz are now possible for IGBT converters, the optimum frequency for minimum volume may be below 20 kHz because of heat sink requirements. A comparative study considers the reactive component versus heat sink volume tradeoff for two 6kW converters, one using ZVS/ZCS and the other using a more conventional circuit with hard switching.

  9. Weather satellite picture receiving stations, APT digital scan converter

    NASA Technical Reports Server (NTRS)

    Vermillion, C. H.; Kamowski, J. C.

    1975-01-01

    The automatic picture transmission digital scan converter is used at ground stations to convert signals received from scanning radiometers to data compatible with ground equipment designed to receive signals from vidicons aboard operational meteorological satellites. Information necessary to understand the circuit theory, functional operation, general construction and calibration of the converter is provided. Brief and detailed descriptions of each of the individual circuits are included, accompanied by a schematic diagram contained at the end of each circuit description. Listings of integral parts and testing equipment required as well as an overall wiring diagram are included. This unit will enable the user to readily accept and process weather photographs from the operational meteorological satellites.

  10. The APA Style Converter: a Web-based interface for converting articles to APA style for publication.

    PubMed

    Li, Ping; Cunningham, Krystal

    2005-05-01

    The APA Style Converter is a Web-based tool with which authors may prepare their articles in APA style according to the APA Publication Manual (5th ed.). The Converter provides a user-friendly interface that allows authors to copy and paste text and upload figures through the Web, and it automatically converts all texts, references, and figures to a structured article in APA style. The output is saved in PDF or RTF format, ready for either electronic submission or hardcopy printing. PMID:16171194

  11. Development, evaluation, and design applications of an AMTEC converter model 

    E-print Network

    Spence, Cliff Alan

    2002-01-01

    An AMTEC converter model was developed and its effectiveness as a design tool was evaluated. To develop the model, requirements of the model were defined, modeling equations were selected, and a methodology for model development was established...

  12. A fast radiation-to-coherent light converter

    SciTech Connect

    Wang, C.L.; Flatley, J.E.; Stewart, P.H.; Bar-Chaim, N.; Lau, K.Y.; Ury, I.; Baltrusaitis, R.M.; Davies, T.J.; Davis, B.A.; Iversen, S.G.

    1988-09-09

    We have developed a radiation-to-coherent light converter (RCLC) with a monolithically integrated semiconductor chip that consists of a chromium-doped GaAs photoconductor detector modulates the laser diode, which has been biased above the lasing threshold, thus converting a radiation pulse to an electric pulse and then to a light pulse. The laser pulse is then transmitted to a fast recorder through a high-bandwidth optical fiber. In the absence of a single-step x-ray pumped laser, our converter appears to be the first integrated device that can efficiently convert x-ray flux into coherent light. This device has been tested successfully with the 50-ps electron beams of a 17-MeV linear accelerator and with 50-ns x-ray pulses from a Z-pinch plasma source. 2 refs., 9 figs.

  13. Protocols for the Equitable Assessment of Marine Energy Converters 

    E-print Network

    Ingram, David; Smith, George; Bittencourt-Ferreira, Claudio; Smith, Helen

    This book contains the suite of protocols for the equitable evaluation of marine energy converters (based on either tidal or wave energy) produced by the EquiMar consortium led by the University of Edinburgh. These protocols ...

  14. Development of AC and DC Power Supply Direct Interface Converter

    NASA Astrophysics Data System (ADS)

    Kato, Koji; Itoh, Jun-Ichi

    This paper proposes a novel control method for a direct interface converter for management of the energy flow in either an AC or DC supply. The proposed converter is constructed based on an indirect matrix converter. Therefore a proposed control strategy is based on an indirect control method with a triangular carrier wave. The basic operation of the proposed control method is confirmed by experimental results. In addition, this paper also proposes a commutation error compensation method of an output voltage error and an input current error for an indirect matrix converter. In the proposed method, the output voltage and input current error by the commutation can be compensated at the same time, because the PWM pulse of each switch is directly compensated. The validity of the proposed method is confirmed by experimental results. Those results prove that the proposed compensation method can decrease total harmonic distortion (THD) of the input and output current.

  15. Randomized modulation of power converters via Markov chains

    E-print Network

    Stankovic, Aleksandar M.

    Randomized modulation of switching in power converters holds promise for reducing filtering requirements and reducing acoustic noise in motor drive applications. This paper is devoted to issues in analysis and synthesis ...

  16. Monolithic series-connected gallium arsenide converter development

    SciTech Connect

    Spitzer, M.B.; McClelland, R.W.; Dingle, B.D.; Dingle, J.E.; Hill, D.S. (Kopin Corp., Taunton, MA (United States)); Rose, B.H. (Sandia National Labs., Albuquerque, NM (United States))

    1991-01-01

    We report the development of monolithic GaAs photovoltaic devices intended to convert light generated by a laser or other bright source to electricity. The converters described here can provide higher operating voltage than is possible using a single-junction converter, owing to use of a monolithic circuit that forms a planar series-connected string of single-junction sub-cells. This planar monolithic circuit is arranged to deliver the desired voltage and current during operation at the maximum power point. The paper describes two-, six-, and twelve-junction converters intended for illumination by a laser diode with a wavelength of 0.8 {mu}m. Design and characterization data are presented for optical power in the range of 100 mW to 1 W. The best conversion efficiency exceeds 50%. 9 refs., 4 figs., 2 tabs.

  17. 31 CFR 800.206 - Convertible voting instrument.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Finance (Continued) OFFICE OF INVESTMENT SECURITY, DEPARTMENT OF THE TREASURY REGULATIONS PERTAINING TO MERGERS, ACQUISITIONS, AND TAKEOVERS BY FOREIGN PERSONS Definitions § 800.206 Convertible voting instrument. The term...

  18. Burnout sensitivity of power MOSFETs operating in a switching converter

    SciTech Connect

    Tastet, P.; Garnier, J. (Centre National d'Etudes Spatiales, Toulouse (France)); Constans, H.; Tizon, A.H. (EREMS, Flourens (France))

    1994-06-01

    Heavy ion tests of a switching converter using power MOSFETs have allowed the authors to identify the main parameters which affect the burnout sensitivity of these components. The differences between static and dynamic conditions are clarified in this paper.

  19. Converting Kohn-Sham eigenenergies into electron binding energies.

    SciTech Connect

    Jellinek, J.; Acioli, P. H.; Chemistry

    2003-05-01

    A new accurate scheme for converting the Kohn-Sham eigenenergies into electron binding energies is formulated. The accuracy of the scheme is illustrated in applications to ten atoms and three molecules.

  20. Silicon RF-Photonic Filter and Down-Converter

    E-print Network

    Tu, Kun-Yii

    An RF-photonic filter and down-converter system based on a compact and fully tunable silicon optical filter has been demonstrated and analyzed. Its frequency down-conversion was implemented using optical heterodyne detection ...