Sample records for sido buck converter

  1. Monolithic quasi-sliding-mode controller for SIDO buck converter with a self-adaptive free-wheeling current level

    NASA Astrophysics Data System (ADS)

    Xiaobo, Wu; Qing, Liu; Menglian, Zhao; Mingyang, Chen

    2013-01-01

    An analog implementation of a novel fixed-frequency quasi-sliding-mode controller for single-inductor dual-output (SIDO) buck converter in pseudo-continuous conduction mode (PCCM) with a self-adaptive freewheeling current level (SFCL) is presented. Both small and large signal variations around the operation point are considered to achieve better transient response so as to reduce the cross-regulation of this SIDO buck converter. Moreover, an internal integral loop is added to suppress the steady-state regulation error introduced by conventional PWM-based sliding mode controllers. Instead of keeping it as a constant value, the free-wheeling current level varies according to the load condition to maintain high power efficiency and less cross-regulation at the same time. To verify the feasibility of the proposed controller, an SIDO buck converter with two regulated output voltages, 1.8 V and 3.3 V, is designed and fabricated in HEJIAN 0.35 ?m CMOS process. Simulation and experiment results show that the transient time of this SIDO buck converter drops to 10 ?s while the cross-regulation is reduced to 0.057 mV/mA, when its first load changes from 50 to 100 mA.

  2. 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.

  3. 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.

  4. 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.

  5. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria (Niskayuna, NY)

    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.

  6. Single Inductor Dual Output Buck Converter

    E-print Network

    Eachempatti, Haritha

    2010-07-14

    -Light load condition????????????? ????????. 32 16 Opamp differentiator??? ??????????????????? ? .. 34 17 Differentiator for )(,1 tV uplow ????????????????????. . 36 18 Differentiator for )(,2 tV... through auxS and nS ??????? ???????????. 44 24 SIDO buck topology ?? ??????.???????????????. . 44 25A. Control of )(1tV using dynamic thresholds??????????????..... 48 25B. Control of )(1tV using static...

  7. A single-inductor dual-output buck converter with pulse-train control

    Microsoft Academic Search

    Xueshan Liu; Jianping Xu; Jinping Wang; Qingbo Mu

    2010-01-01

    Voltage-mode pulse-train (PT) control for single-inductor dual-output (SIDO) buck converter operating in discontinuous-conduction mode (DCM) is investigated in this paper. By using time-multiplexing (TM) scheme, each output of converter is regulated in its corresponding time slot to avoid cross-regulation of two outputs. “Blank pulse” is adopted to improve the performances of the converter in light load. No error amplifier and

  8. Mix-Voltage Conversion for Single-Inductor Dual-Output Buck Converters

    Microsoft Academic Search

    Chun-Shih Huang; Dan Chen; Ching-Jan Chen; Kwang H. Liu

    2010-01-01

    A single-inductor dual-output (SIDO) buck converter has recently found applications in hand-held battery-powered electronic devices. The circuit operation and the functional interdependencies among basic converter parameters such as dc voltage gains, transistor duty cycles, and load current levels are much more complicated than those of the single-output counterpart. In this paper, a rigorous analysis was conducted to develop dc equations

  9. Mix-voltage conversion for single-inductor dual-output buck converters

    Microsoft Academic Search

    Chun-Shih Huang; Dan Chen; Kwang H. Liu

    2009-01-01

    A single-inductor dual-output (SIDO) buck converter has recently found applications in hand-held battery-powered electronic devices. The circuit operation and the functional interdependencies among basic converter parameters such as DC voltage gains, transistor duty cycles, and load current levels are much more complicated than those of the single-output counterpart. In this paper, a rigorous analysis was conducted to develop DC equations

  10. Modeling and design of feedback loops for a voltage-mode single-inductor dual-output buck converter

    Microsoft Academic Search

    Kun-Yu Lin; Chun-Shih Huang; Dan Chen; Kwang H. Liu

    2008-01-01

    In recent years, single-inductor dual-output (SIDO) converters have found applications in hand-held electronic devices. The focus of the paper is about the modeling and the design of the feedback control loop for a voltage-mode SIDO buck converter working in continuous conduction mode. A small-signal model was developed and verified by simulations and experimental results. This model is practically useful in

  11. A single-inductor dual-output buck converter with self-adapted PCCM method

    Microsoft Academic Search

    Yang Yang; Sun Liang; Wu Xiaobo

    2009-01-01

    A single-inductor dual-output (SIDO) buck converter controller is presented, which operates in self-adapted pseudo-continuous-conduction-mode (PCCM) with adjustable dc current levels. Freewheel switching control has been introduced to realize large load current with smaller current ripple, while cross regulation can be minimized. Furthermore, the dc current level of subconverters can be adjusted according to each load. The controller was designed and

  12. A Dual Supply Buck Converter with Improved Light Load Efficiency

    E-print Network

    Chen, Hui

    2013-05-02

    . Typical switched-capacitor converter (single phase) .......................................... 8 Fig. 2. 4. Buck converter with ideal switch model ........................................................... 10 Fig. 2. 5. Waveform at the switching node... hysteresis comparator ..................................... 43 Fig. 4. 5. Schematic of hysteresis comparator .................................................................. 44 Fig. 4. 6. Clock signals for power switches...

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

    E-print Network

    Sanders, Seth

    presents an ultra-low-quiescent-power dual- mode digitally-controlled buck converter IC for cellular phone converter IC system clock Fig. 1. Block diagram of dual-mode buck converter IC and external LC filter applications. While the cellular phone is in talk mode, the load on the buck converter is high and pulse width

  14. Peak inductor current and differential-mode voltage control of single-inductor dual-output buck converters in continuous conduction mode

    Microsoft Academic Search

    Wei Wang; Jianping Xu; Xiaojuan Wei; Guohua Zhou

    2009-01-01

    This paper investigates a new control technique for non-isolated single-inductor dual-output (SIDO) buck converters using peak inductor current and differential-mode voltage. The proposed control method applied for SIDO converters operating in continuous conduction mode (CCM) realizes independent control of each output of the SIDO converter to reduce the cross-regulation problem. Simulation results are presented in this paper to verify the

  15. Buck converter controlled by using variable switching frequency technique

    Microsoft Academic Search

    A. Julsereewong; S. Pongswatd; P. Julsereewong; K. Tirasesth; H. Sasaki; Y. Shi

    2008-01-01

    In this paper, a linearly tunable voltage controlled oscillator with negatively proportional characteristic, termed VCOTheta, is described. Using the VCOTheta and analog PI controller in feedback path of a buck converter operating in continuous condition mode, a control technique with variable switching frequency is presented. No filtering capacitor is required in the proposed technique that provides the advantage of a

  16. Buck-boost DC\\/DC converter for aeronautical applications

    Microsoft Academic Search

    Luigi Rubino; Beniamino Guida; Felice Liccardo; Pompeo Marino; Alberto Cavallo

    2010-01-01

    In this document a DC\\/DC converter for power conversion between +28V\\/+270V voltage levels is presented, and the main characteristics of the converter are discussed. The topological structure is first introduced, outlining the hardware components used and the modular approach. The step-down (or Buck) and step-up (or Boost) modulations are then discussed, focusing on the switching signals to drive the low-voltage

  17. Cross-Regulation-Suppression control scheme for CCM Single-Inductor-Dual-Output buck converter with ordered-power-distributive control

    Microsoft Academic Search

    Cheng Huang; Philip K. T. Mok

    2011-01-01

    A Single-Inductor-Dual-Output (SIDO) buck converter with Cross-Regulation-Suppression (CRS) control scheme is presented. The converter operates in continuous- conduction-mode (CCM) and employs ordered-power- distributive control (OPDC) to distribute the inductor current to the two outputs. The novel CRS control method is used to suppress the cross-regulation (CR) of the SIDO which is an important issue in OPDC CCM converter design. On-chip

  18. A dual mode high efficiency buck DC-DC converter

    Microsoft Academic Search

    Xu Gong; Jinguang Jiang; Xifeng Zhou; Zhongzhi Yuan

    2011-01-01

    This paper proposes a pulse width modulation-pulse skipping modulation (PWM-PSM) dual mode control and high efficiency buck dc-dc converter with 91.7% peak efficiency. A simple but steady PWM-PSM automatic switching module is proposed to improve the conversion efficiency when the load is light and synchronous rectifier is used to boost the conversion efficiency when the load is heavy. At the

  19. Dual-edge modulated four-switch Buck-Boost converter

    Microsoft Academic Search

    Xiaoyong Ren; Xinbo Ruan; Hai Qian; Mingqiu Li; Qianhong Chen

    2008-01-01

    Four-switch Buck-Boost (FSBB) converter is a simplified cascaded Buck and Boost, it has two active power switches and two synchronous rectifiers (SRs). Compared to the traditional Buck-Boost converter, FSBB converter has some advantages such as positive output and lower voltage stress across the power devices. The two active power switches can be controlled independently, thus two freedoms, i.e. the duty

  20. A single-inductor dual-output pseudo-DCM\\/CCM buck and boost converter with adaptive DC current compensation

    Microsoft Academic Search

    Jingbin Jia; Ka Nang Leung

    2009-01-01

    The proposed single-inductor dual-output (SIDO) buck-boost DC-DC converter operating in pseudo-DCM\\/CCM mode can adaptively increase the pseudo DC inductor current to improve the transient load response and the load driving capability in terms of the load change. A maximum duty cycle limiter is used to remove cross regulation and determine the compensation current on the set pseudo DC current. A

  1. Non-inverting buck-boost converter for fuel cell applications

    Microsoft Academic Search

    Erik Schaltz; Peter Omand Rasmussen; Alireza Khaligh

    2008-01-01

    Fuel cell DC\\/DC converters often have to be able to both step-up and step-down the input voltage, and provide a high efficiency in the whole range of output power. Conventional negative output buck-boost and non-inverting buck-boost converters provide both step-up and step-down characteristics. In this paper the non-inverting buck-boost with either diodes or synchronous rectifiers is investigated for fuel cell

  2. Dual charge mode control of a current fed boost-buck push pull converter

    Microsoft Academic Search

    William A. Peterson; Steven L. Plaskon

    1998-01-01

    A control scheme is presented which allows control of a push-pull converter operating in boost and buck modes with seamless transformation between modes. Independent charge mode control on each leg of the push-pull converter allows one control scheme to be used for control in regions where the sensed current is both monotonically increasing (buck mode) and also where the current

  3. An Ultra-Low-Quiescent-Current Dual-Mode Digitally-Controlled Buck Converter IC for Cellular Phone Applications

    E-print Network

    Sanders, Seth

    An Ultra-Low-Quiescent-Current Dual-Mode Digitally-Controlled Buck Converter IC for Cellular Phone-Low-Quiescent-Current Dual-Mode Digitally-Controlled Buck Converter IC for Cellular Phone Applications Copyright Fall 2003 by Jinwen Xiao #12;1 Abstract An Ultra-Low-Quiescent-Current Dual-Mode Digitally-Controlled Buck Converter

  4. ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters

    NASA Technical Reports Server (NTRS)

    Schoenfeld, A. D.; Yu, Y.

    1973-01-01

    Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency.

  5. A novel interleaved and isolated buck converter with high voltage ratio

    Microsoft Academic Search

    Huang-Hua Chiu; Ming-Fa Tsai; Chung-Shi Tseng; Shu-Yi Yen

    2010-01-01

    This paper presents a novel interleaved and isolated DC to DC buck converter with high voltage ratio. The converter consists of a half-bridge converter and a forward converter which are connected in parallel with a common load. As being one of interleaved DC to DC converters, it has smaller output current ripples within wide duty ratio, and it also has

  6. 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 ...

  7. Improving the control strategy for a four-switch buck-boost converter

    E-print Network

    Whitaker, Michael Peter

    2007-01-01

    The four-switch buck-boost converter, such as implemented with the Linear Technology LTC3440 integrated circuit, is useful in many applications. While this topology can be highly efficient, new strategies for controlling ...

  8. Highly Efficient Tri-Mode Control of Buck Converters with Load Sensing Technique

    Microsoft Academic Search

    Hong-Wei Huang; Chieh-Ching Chien; Ke-Horng Chen; Sy-Yen Kuo

    2006-01-01

    A highly efficient tri-mode buck converter with a novel load sensor circuit is proposed in this paper. The combination of pulse-width modulation (PWM), pulse-frequency modulation (PFM) and pulse-skipping circuit makes it efficient to operate in wide loading region. By using the novel load sensor, the buck converter can achieve high efficiency for the load range from 3 mA to 400

  9. On-chip compensated error amplifier for voltage-mode buck converters

    Microsoft Academic Search

    Shaowei Zhen; Bo Zhang; Ping Luo; Jun Chen; Huiming Wu

    2010-01-01

    An on-chip compensated error amplifier in a voltage-mode buck converter is proposed in the paper. The compensated error amplifier is composed of two blocks, unit gain zero generation block and gain block, realizing phase shift and gain of the feedback loop, respectively. Compared to conventional type III compensated error amplifier in voltage-mode buck converter, the proposed circuit has much smaller

  10. Elimination of sub-harmonic oscillation of digital average current control buck converter

    Microsoft Academic Search

    Guohua Zhou; Jianping Xu; Jinping Wang; Qingbo Mu

    2008-01-01

    The sub-harmonic oscillation of digital average current (DAC) control buck converter with single-edge modulation (trailing-edge modulation and leading-edge modulation) is investigated in this paper. It has been shown that both digital slope compensation (DSC) and digital reposition compensation (DRC) of duty ratio ac component can not be used to eliminate the sub-harmonic oscillation of DAC control buck converter with single-edge

  11. 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

  12. 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.

  13. Modeling and Simulation of Dual-Mode DC\\/DC Buck Converter

    Microsoft Academic Search

    Zhuo Bi; Wenbin Xia

    2010-01-01

    A dual-mode DC\\/DC buck converter is presented in this paper. The converter operation includes the soft start, sawtooth oscillator, zero-current detector and PWM\\/PFM detector. According to the judgment of zero-current detector and PWM\\/PFM detector, the converter can switch automatically between pulse width modulation (PWM) mode and pulse frequency modulation (PFM) mode. Because of this, the proposed converter model has the

  14. Design of the dual mode DC-DC buck converter using low power control method

    Microsoft Academic Search

    Dong-kyun Lim; Seung-chan Park; Won Kim; Jung-jin Hwang; Hak-jin Jung; Li-min Park; Kwang-sub Yoon

    2009-01-01

    This paper describes a dual-mode DC-DC buck converter using a low power control method for mobile devices. Under a light load condition, the proposed converter within a PFM mode utilizes multiple steps of the state machine to control the load sensing circuit and enhances the efficiency of the PFM mode. The measurement results demonstrate the peak efficiency of 93% and

  15. Design of high efficiency dual-mode buck DC-DC converter

    Microsoft Academic Search

    Lai Xinquan; Zeng Huali; Ye Qiang; He Huisen; Zhang Shasha; Sun Yuqing

    2010-01-01

    A buck DC---DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current, and it can operate with an input range of 4.5 to 30 V. At light load current, the converter operates in skip mode. The converter enters PWM mode operation with increasing load current. It reduces the switching loss at light

  16. Design and analysis of buck converter with pulse-skipping modulation

    Microsoft Academic Search

    S. Angkititrakul; H. Hu

    2008-01-01

    In this paper, operation and analysis of synchronous buck converter with pulse-skipping mode are discussed. The pulse-skipping mode is generally employed in switch mode power supplies to improve efficiency at light load condition. The improvement in efficiency is determined by the periods of skipping and active operations, which depend on output filters of the converter. The impact of the output

  17. Digital PWM/PFM Controller with Input Voltage Feed-Forward for Synchronous Buck Converters

    E-print Network

    buck DC-DC converters. The controller includes automatic PWM/PFM mode switching and effective for DC-DC converters in low-power battery-operated systems. Motivated by light-load energy savings-DC applications. In analog DC-DC controllers, well known approaches to improving light-load efficiency include

  18. A Family of Isolated Interleaved Boost and Buck Converters With Winding-Cross-Coupled Inductors

    Microsoft Academic Search

    Wuhua Li; Xiangning He

    2008-01-01

    A boost-type converter is derived by inserting a third winding of the winding-cross-coupled inductors (WCCIs) between the secondary winding and the output diode of the interleaved flyback converter in this paper. A family of isolated interleaved boost or buck DC\\/DC converters with WCCIs is summarized by employing the four main types of interleaved structures, which is suitable for step-up or

  19. A comprehensive analysis of current-mode control for DCM buck-boost converters

    Microsoft Academic Search

    Keng C. Wu

    2004-01-01

    Comprehensive analyses for the buck-boost, pulse width modulation DC\\/DC converters applying peak current current-mode control are given. The analysis provides closed-form solutions for steady-state output, small-signal loop gain, and conducted susceptibility. It also proves that the state-space averaged model developed for converter using a single-loop voltage-mode control is valid for a current-mode-controlled converter.

  20. A High Efficiency Dual-Mode Buck Converter IC For Portable Applications

    Microsoft Academic Search

    Wan-Rone Liou; Mei-Ling Yeh; Yueh Lung Kuo

    2008-01-01

    This paper presents the design of a novel wide output current range dual-mode dc to dc step-down (Buck) switching regulator\\/converter. The converter can adaptively switch between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Under light load condition the converter enters PFM mode. The function of closing internal idle circuits is implemented to save unnecessary

  1. A New BLDC Motor Drives Method Based on BUCK Converter for Torque Ripple Reduction

    Microsoft Academic Search

    Zhang Xiaofeng; Lu Zhengyu

    2006-01-01

    This paper presents a comprehensive analysis on torque ripples of brushless dc motor drives in conduction region and commutation region. A novel method for reducing the torque ripple in brushless dc motors with a single current sensor has been proposed by adding BUCK converter in the front of 3-phase inverter. In such drives, torque ripple suppression technique is theoretically effective

  2. 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, ...

  3. Non-linear Cascade Control of DC\\/DC Buck Converter

    Microsoft Academic Search

    K. M. Tsang; W. L. Chan

    2008-01-01

    A model-based cascade controller design is presented for the control of DC\\/DC Buck converters. Detailed discussions in the setting of bandwidth for the current loop and voltage loop have been given. Robustness analysis of the cascade controller against load changes and supply changes are also presented. Finally, a deadband relay is introduced in the voltage loop to improve the disturbance

  4. Power quality based performance analysis of a dual buck converter fed four-quadrant dc drive

    Microsoft Academic Search

    A. N. Arvindan

    2011-01-01

    The phase-controlled dc drive operation is well established, however, this paper investigates the operation of the separately excited dc machine in each of the four quadrants when fed by the symmetrical multipulse modulated, improved power quality, single-phase, dual buck converter. The armature control of the dc machine with constant load torque is undertaken in both clockwise and anticlockwise directions in

  5. An integrated dual-output buck converter based on sliding mode control

    Microsoft Academic Search

    Miguel Angel Rojas-Gonzalez; Joselyn Torres; Edgar Sanchez-Sinencio; Pavan Kumar

    2012-01-01

    The design, implementation, and testing of an integrated dual-output buck converter is presented in this paper. The proposed architecture consists of a simple, versatile, and robust hysteretic controller based on sliding mode theory. The proposed topology implements only three switches (instead of four switches in conventional solutions), and can save additional silicon area with proper design of the power switches

  6. A 4?A-quiescent-current dual-mode buck converter IC for cellular phone applications

    Microsoft Academic Search

    Jinwen Xiao; Angel Peterchev; Jianhui Zhang; Seth Sanders

    2004-01-01

    This digitally-controlled buck converter IC occupies 2 mm2 active area in 0.25mum CMOS, and the quiescent current is 4VA, representing more than a 3-fold improvement over the leading state-of-the-art analog approach. As a result, cellular phone standby time can be extended by up to 3 times

  7. Large signal design of a buck converter for high power dc\\/ac conversion

    Microsoft Academic Search

    J. C. Marpinard; J. Jalade; M. Valentin

    1981-01-01

    Parameters defining the stable operation of the closed loop system in buck converter design considerations are discussed. Such parameters as poles and transmittance gains are examined, the study is aimed at determining suitable corrective networks giving the smallest modulus of the characteristic equation roots, and at determining parameter tolerances which allow acceptable performances compatible with stability criteria. It is found

  8. Efficiency estimation in digitally-controlled dc-dc buck converters based on single current sensing

    Microsoft Academic Search

    S. Saggini; W. Stefanutti; P. Mattavelli; A. Carrera

    2008-01-01

    This paper proposes an efficiency estimator for dc-dc buck converters suitable for on-chip integration in the digital IC controller. The proposed solution is tailored for distributed power architectures, where the on-line efficiency measurement or estimation of each dc-dc converter is useful in order to perform a system power management and to monitor the status of each point of load (POL)

  9. Closed-Form Critical Conditions of Saddle-Node Bifurcations for Buck Converters

    E-print Network

    Chung-Chieh Fang

    2012-04-18

    A general and exact critical condition of saddle-node bifurcation is derived in closed form for the buck converter. The critical condition is helpful for the converter designers to predict or prevent some jump instabilities or coexistence of multiple solutions associated with the saddle-node bifurcation. Some previously known critical conditions become special cases in this generalized framework. Given an arbitrary control scheme, a systematic procedure is proposed to derive the critical condition for that control scheme.

  10. A High Efficiency Dual-Mode Buck Converter IC For Portable Applications

    Microsoft Academic Search

    Wan-Rone Liou; Tsung-Hsing Chen; Yuen-Lung Kuo; Tang-Yu Huang; Mei-Ling Yen

    2007-01-01

    This paper presents the design of a novel wide output current range dual-mode DC to DC step-down (buck) switching regulator\\/converter. The converter can adaptively switch between pulse-width modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Soft start operation is designed to eliminate the excess large current at the start up of the regulator. The chip has

  11. A study of modeling and simulation for interleaved buck converter

    Microsoft Academic Search

    Mohamed. A. Shrud; Ahmad Kharaz; Ahmed. S. Ashur; Mustafa Shater; Ismail Benyoussef

    2010-01-01

    This paper focuses on modeling, analysis and simulation of a 42V\\/14V dc\\/dc converter based architecture. This architecture is considered to be a technically viable solution for automotive dual-voltage power system in passenger cars of the near future. An interleaved dc\\/dc converter system is chosen for the automotive converter topology due to its advantages regarding filter reduction, dynamic response, and power

  12. Modeling and simulation of automotive interleaved buck converter

    Microsoft Academic Search

    M. A. Shrud; Amar Bonsbaine; A. S. Ashur; Richard Thorn; Tammam Benmusa

    2009-01-01

    This paper focuses on modeling, analysis and simulation of a 42V\\/14V dc\\/dc converter based architecture. This architecture is considered to be technically a viable solution for automotive dual-voltage power system for passenger car in the near further. An interleaved dc\\/dc converter system is chosen for the automotive converter topology due to its advantages regarding filter reduction, dynamic response, and power

  13. Advanced buck converter power supply ABCPS for APT

    SciTech Connect

    Street, R.; Overett, T.; Bowles, E. [General Atomics, San Diego, CA (United States)

    1998-12-31

    The United States Department of Energy (DOE) is planning to fabricate an Accelerator for the Production of Tritium (APT) at their Savannah River Site, to provide Tritium for national defense. The 1700 million electron volt (MeV) proton beam accelerator will be powered by radio frequency (RF) klystrons. A direct current (DC) power supply is required for each of the approximately two hundred and fifty 1-megawatt (MW) continuous wave klystrons in the RF power system. The requirements are that the power supply meet output performance specifications, provide fault protection for the klystron, have high efficiency, high reliability, good maintainability, and be readily manufacturable. As the power supplies are one of the largest cost elements in the accelerator, a technology review was made to determine the most economical approach to satisfy the requirements. A switch-mode power supply employing a buck-regulator was identified as being potentially the lowest cost approach. As the switch represents a certain development risk, a small-scale prototype has been constructed for evaluation, and has resulted in the decision to fabricate a full-scale prototype power supply. A description of the hardware will be presented.

  14. A 1.2V buck converter with a novel on-chip low-voltage current-sensing scheme

    Microsoft Academic Search

    Chi Yat Leung; Philip K. T. Mok; Ka Nang Leung

    2004-01-01

    A low-voltage on-chip current-sensing circuit for buck power converter is proposed. The minimum supply voltage of the proposed current-sensing circuit is 1.2V (where Vth = 0.85V at room temperature), and the sensing accuracy is higher than 94%. The proposed buck converter is able to operate at a 1.2-V supply with higher than 98% power-conversion efficiency and with a maximum output

  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. A high efficiency 4-output single inductor DC–DC buck converter with self boosted snubber

    Microsoft Academic Search

    Edoardo Bonizzoni; Piero Malcovati; Franco Maloberti

    2011-01-01

    This paper presents a single-inductor 4-outputs DC–DC buck converter. In order to independently regulate the four output voltages,\\u000a a multiple control loop operates on linear combinations of the output voltage errors. An original self-boosted snubber circuit\\u000a enables load power switches control signals boosting without area and power efficiency penalties. The circuit, fabricated\\u000a using a 0.5-?m CMOS process, provides four output

  17. PWM\\/PSM Dual-Mode Controller for High Efficiency DC-DC Buck Converter

    Microsoft Academic Search

    Yidie Ye; Jianping Qiu; Lingling Dong; Lenian He

    2010-01-01

    This paper introduces a novel method of realizing PWM\\/PSM dual-mode controller for high efficiency DC-DC buck converters. A minimum duty cycle control module is added to the PWM control loop, and with a simple logic control, the system can work in PSM mode when the load is light to improve the efficiency of the system over wide load range. A

  18. 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

  19. An ultra-low-power digitally-controlled buck converter IC for cellular phone applications

    Microsoft Academic Search

    Jinwen Xiao; Angel Peterchev; Jianhui Zhang; Seth Sanders

    2004-01-01

    This paper describes a dual-mode digitally-controlled buck converter IC for cellular phone applications. An architecture employing internal power management is introduced to ensure voltage compatibility between a single-cell lithium-ion battery voltage and a low voltage integrated circuit technology. Special purpose analog and digital interface elements are developed. These include a ring-oscillator based ADC (ring-ADC), which is nearly entirely synthesizable, robust

  20. Fixed-Frequency Quasi-Sliding Mode Controller for Single-Inductor-Dual-Output Buck Converter in Pseudo-Continuous Conduction Mode

    Microsoft Academic Search

    Qing Liu; Xiaobo Wu; Liang Yin

    \\u000a Based on the quasi-sliding mode theory, a novel fixed-frequency nonlinear controller for single-inductor dual-output (SIDO)\\u000a buck converter in pseudo-continuous conduction mode (PCCM) is presented in this paper. The main advantage of this nonlinear\\u000a controller is that both small and large signal variations around the operating point are taken into account, which results\\u000a in better transient response. To validate the feasibility

  1. A single-inductor dual-output pseudo-DCM\\/CCM buck and boost converter in 90nm CMOS technology

    Microsoft Academic Search

    Jingbin Jia; Ka Nang Leung

    2008-01-01

    A single-inductor dual-output DC-DC converter designed in a 90 nm CMOS technology is presented in this paper. One of the sub-converters is a buck converter, and the other one is a boost converter. There are totally five power switches in the power stage. The values of the off-chip inductor and capacitors at the output of each sub-converter are 1 ¿H

  2. 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.

  3. 26.2 Single-Inductor Dual-Input Dual-Output Buck-Boost Fuel Cell-Li Ion Charging DC-DC Converter Supply

    E-print Network

    Rincon-Mora, Gabriel A.

    1 26.2 Single-Inductor Dual-Input Dual-Output Buck-Boost Fuel Cell-Li Ion Charging DC-DC Converter [2]. As a result, buck or boost single-inductor, dual-input, dual-output (SIDIDO) converters enjoy. From a system perspective, the converter has two modes of operation: light (LT) and heavy (HV). In LT

  4. Minimized Transient and Steady-State Cross Regulation in 55-nm CMOS Single-Inductor Dual-Output (SIDO) Step-Down DC-DC Converter

    Microsoft Academic Search

    Yu-Huei Lee; Tzu-Chi Huang; Yao-Yi Yang; Wen-Shen Chou; Ke-Horng Chen; Chen-Chih Huang; Ying-Hsi Lin

    2011-01-01

    A single-inductor dual-output (SIDO) step-down DC-DC converter with continuous conduction mode (CCM) oper- ation is proposed to achieve an area-efficient power management module. The low-voltage energy distribution controller (LV-EDC) can simultaneously guarantee good voltage regulation and low output voltage ripple. With the proposed dual-mode energy de- livery methodology, cross regulation in steady-state output voltage ripple, which is rarely discussed, and

  5. A 65nm 10MHz single-inductor dual-output switching buck converter with time-multiplexing control

    Microsoft Academic Search

    Miao Yang; Weifeng Sun; Shen Xu; Shengli Lu; Longxing Shi

    2011-01-01

    A 10MHz switching frequency integrated single-inductor dual-output buck converter with time-multiplexing (TM) control in discontinuous conduction mode (DCM) is proposed. This converter only uses one 0.5uH off-chip inductor and one error amplifier to provide two independent supply voltages (1.2V and 1.8V). Simulation results prove the converter is high efficient and stable. The converter was fabricated using SMIC 65nm digital CMOS

  6. Single-inductor dual-output DC\\/DC buck converter with high full-load efficiency

    Microsoft Academic Search

    Junjie Qian; Zhibiao Shao

    2009-01-01

    This paper presents a novel topology of DC\\/DC buck converter which is high power efficiency, low cost and small size. This converter adopts PWM and PFM dual modes control to achieve high efficiency over full load and it works at PWM mode at heavy load, PFM mode at light load. Also time-multiplexing control is accepted to realize two independent outputs

  7. 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 ...

  8. 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

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

    PubMed

    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

  10. Fast-response single-inductor dual-output hysteresis-current-controlled DC–DC buck converter

    Microsoft Academic Search

    Jiann-Jong Chen; Bo-Han Hwang; Jui-Hsuan Hsu; Yuh-Shyan Hwang; Cheng-Chieh Yu

    A fast-response single-inductor dual-output hysteresis-current-controlled DC–DC buck is proposed for enhancing the transient\\u000a characteristics of switching DC–DC converters and fabricated with TSMC 0.35 ?m DPQM CMOS processes. By adopting a hysteresis-current-controlled\\u000a DC–DC buck converter, it is demonstrated that the hysteresis-current-controlled technique have improved dynamic response of\\u000a load variations whether the load current is light or heavy. Fast-response structure achieves 5 ?s response

  11. Design of high efficiency dual-mode buck DC-DC converter

    NASA Astrophysics Data System (ADS)

    Xinquan, Lai; Huali, Zeng; Qiang, Ye; Huisen, He; Shasha, Zhang; Yuqing, Sun

    2010-11-01

    A buck DC—DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current, and it can operate with an input range of 4.5 to 30 V. At light load current, the converter operates in skip mode. The converter enters PWM mode operation with increasing load current. It reduces the switching loss at light load and standby state, which results in prolonging battery lifetime and stand-by time. Meanwhile, externally adjustable soft-start minimizes the inrush supply current and avoids the overshoot of output voltage at initial startup. The regulator is fabricated by a 0.6 ?m CDMOS process. The test results show that, under the condition of 3.3 V output, the efficiency is up to 64% at 5 mA and the maximum efficiency is 95.5%.

  12. 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.

  13. Peak inductor current and differential-mode voltage control of single-inductor multiple-output buck converters in CCM

    Microsoft Academic Search

    Songrong Wu; Wei Wang; Jianping Xu; Guohua Zhou; Xiaojuan Wei

    2009-01-01

    A new control technique, peak inductor current and differential-mode voltage control technique, for non-isolated single-inductor multiple-output (SIMO) buck converters is investigated in this paper. The proposed control method can realize independent control of different output of the SIMO converters operating in continuous conduction mode (CCM) to reduce cross-regulation effect. By taking a three outputs converter as an example, simulation is

  14. A single-inductor dual-output buck converter with voltage mode pulse-train control

    Microsoft Academic Search

    Xueshan Liu; Jianping Xu; Zhifei Lu; Jinping Wang

    2010-01-01

    Voltage mode pulse-train (PT) control technique for single-inductor dual-output (SIDO) dc-dc converters operating in discontinuous-conduction mode (DCM) is investigated in this paper. By using time-multiplexing(TM) scheme, each output of converter is regulated in its corresponding time slot to avoid cross-regulation. The control time of each output is set according to the maximum power of corresponding output, thus the utilization rate

  15. Efficiency Analysis of a High Frequency Buck Converter for On-Chip Integration with a Dual-VDD Microprocessor

    E-print Network

    Friedman, Eby G.

    -VDD Microprocessor Volkan Kursun, Siva G. Narendra* , Vivek K. De* , and Eby G. Friedman Department of Electrical. Full integration of a high efficiency buck converter on the same die with a dual-VDD microprocessor of high performance microprocessors are the two primary reasons for implementing a dual-VDD microprocessor

  16. 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

  17. Analysis of the novel soft-switching buck-boost type AC-DC converter using magnetic coupling

    Microsoft Academic Search

    H. Matsuo; H. Watanabe; F. Kurokawa; Lishan Tu

    2000-01-01

    This paper presents the design-oriented analysis of the novel soft-switching buck-boost type AC-DC converter with high power efficiency and high power factor. In this AC-DC converter, the power factor and input current harmonic distortion are improved by using the third winding of the energy-storage reactor, and the high power efficiency is achieved by the soft-switching operation of the main power

  18. Design of Digital Tri-mode Adaptive-Output Buck–Boost Power Converter for Power-Efficient Integrated Systems

    Microsoft Academic Search

    Feng Luo; Dongsheng Ma

    2010-01-01

    An integrated buck-boost converter with a tri-mode digital control is presented. It employs an adaptive step-up\\/down voltage conversion to enable a wide range of output voltage. This is beneficial to the ever-increasing electronic systems that employ dynamic voltage scaling (DVS) techniques for power-efficient operations. Three control modes are employed in the converter to operate jointly and seamlessly for performance optimization

  19. Discrete-Time Poles and Dynamics of Discontinuous Mode Boost and Buck Converters Under Various Control Schemes

    E-print Network

    Chung-Chieh Fang

    2012-11-19

    Nonlinear systems, such as switching DC-DC boost or buck converters, have rich dynamics. A simple one-dimensional discrete-time model is used to analyze the boost or buck converter in discontinuous conduction mode. Seven different control schemes (open-loop power stage, voltage mode control, current mode control, constant power load, constant current load, constant-on-time control, and boundary conduction mode) are analyzed systematically. The linearized dynamics is obtained simply by taking partial derivatives with respect to dynamic variables. In the discrete-time model, there is only a single pole and no zero. The single closed-loop pole is a linear combination of three terms: the open-loop pole, a term due to the control scheme, and a term due to the non-resistive load. Even with a single pole, the phase response of the discrete-time model can go beyond -90 degrees as in the two-pole average models. In the boost converter with a resistive load under current mode control, adding the compensating ramp has no effect on the pole location. Increasing the ramp slope decreases the DC gain of control-to-output transfer function and increases the audio-susceptibility. Similar analysis is applied to the buck converter with a non-resistive load or variable switching frequency. The derived dynamics agrees closely with the exact switching model and the past research results.

  20. Current-mode DC-DC buck converter with reliable hysteretic-mode control and dual modulator for fast dynamic voltage scaling

    Microsoft Academic Search

    Jungmoon Kim; Hyunho Chu; Chulwoo Kim

    2009-01-01

    This paper describes an integrated current-mode buck converter with reliable hysteretic mode controller and modulators for fast dynamic voltage scaling (DVS). The proposed mode controller and modulators enable the DC-DC buck converter to perform its smooth mode transitions at optimal points. The continuous current-limiting and DCM controls drive the DVS to track the reference at the maximum speed in both

  1. A Comparative Study of Boundary Control With First and Second-Order Switching Surfaces for Buck Converters Operating in DCM

    Microsoft Academic Search

    Kelvin Ka-Sing Leung; Henry Shu-hung Chung

    2007-01-01

    A performance comparison of boundary control with the first-(sigma1) and second-order(sigma2) switching surfaces for buck converters operating in discontinuous conduction mode (DCM) is presented in this paper. Performance attributes under investigation include the average output voltage, output ripple voltage, switching frequency, parametric sensitivities to the component values, and large signal characteristics. Due to the presence of the output hysteresis band,

  2. Asynchronous dual-mode buck converter design with protection circuits in 0.13µm CMOS process for battery applications

    Microsoft Academic Search

    Jefferson A. Hora; Jiun-Chang Zeng; Wan-Rone Liou

    2009-01-01

    An asynchronous architecture dual-mode DC-DC buck converter utilizing an external Schottky diode was evaluated and implemented in SMIC 0.13 ?m 1P6M 3.3\\/2.5 V logic signal CMOS technology. This paper aimed to employ a simple, low cost, and small solution size with on-chip compensation implementation while not compromising high efficiency requirement. Maintaining high efficiency is achieved by adopting a switch-mode pulse-width

  3. 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

  4. Three-Mode Dual-Frequency Two-Edge Modulation Scheme for Four-Switch Buck–Boost Converter

    Microsoft Academic Search

    Xiaoyong Ren; Xinbo Ruan; Hai Qian; Mingqiu Li; Qianhong Chen

    2009-01-01

    Four-switch buck-boost (FSBB) converter features low-voltage stress across the power switches and positive output voltage. They have two active power switches and two synchronous rectifiers, so two freedoms, i.e., the duty cycles of the two active switches, are available to regulate the output voltage. This paper proposes a two-edge modulation (TEM), in which the two active switches are trailing-edge and

  5. A Noise-Shaped Buck DC–DC Converter With Improved Light-Load Efficiency and Fast Transient Response

    Microsoft Academic Search

    Wei Yan; Wenhong Li; Ran Liu

    2011-01-01

    A noise-shaped synchronous buck dc–dc converter based on a third-order active–passive continuous-time sigma–delta modulator is presented. Detailed system modeling and loop design methodology are discussed. A dual-mode compensator is proposed to achieve the loop stability over a wide load range. The light-load efficiency is improved by the proposed dynamic width control and sigma–delta pulse-skip mode techniques. In order to get

  6. A dual-mode fast-transient average-current-mode buck converter without slope-compensation

    Microsoft Academic Search

    Bo-Han Hwang; Yan-Chong Jhang; Jiann-Jong Chen; Yuh-Shyan Hwang

    2011-01-01

    A dual-mode fast-transient average-current-mode buck converter without slope-compensation is proposed in this paper. The benefits of the average-current-mode are fast-transient response, simple compensation design, and no requirement for slope-compensation, furthermore, that minimizes some power management problems, such as EMI, size, design complexity, and cost. Average-current-mode control employs two loop control methods, an inner loop for current and an outer one

  7. Comparison study on digital peak current, digital peak voltage, and digital peak voltage\\/peak current Controlled Buck Converter

    Microsoft Academic Search

    Guohua Zhou; Jianping Xu; Jinping Wang; Yanyan Jin

    2009-01-01

    Digital peak current (DPC) control, digital peak voltage (DPV) control, and digital peak voltage\\/peak current (DPV\\/DPC) control of buck converter with leading-edge modulation are studied and compared in this paper. The AC small signal transfer functions of control-to-output, input-to-output and output impedance are derived and the corresponding comparison studies are performed. Transient simulation is also performed to verify the analysis

  8. Buck-boost converter for simultaneous semi-active vibration control and energy harvesting for electromagnetic regenerative shock absorber

    NASA Astrophysics Data System (ADS)

    Li, Peng; Zhang, Chongxiao; Kim, Junyoung; Yu, Liangyao; Zuo, Lei

    2014-04-01

    Regenerative semi-active suspensions can capture the previously dissipated vibration energy and convert it to usable electrical energy for powering on-board electronic devices, while achieve both the better ride comfort and improved road handling performance at the same time when certain control is applied. To achieve this objective, the power electronics interface circuit connecting the energy harvester and the electrical loads, which can perform simultaneous vibration control and energy harvesting function is in need. This paper utilized a buck-boost converter for simultaneous semi-active vibration control and energy harvesting with electromagnetic regenerative shock absorber, which utilizes a rotational generator to converter the vibration energy to electricity. It has been found that when the circuit works in discontinuous current mode (DCM), the ratio between the input voltage and current is only related to the duty cycle of the switch pulse width modulation signal. Using this property, the buck-boost converter can be used to perform semi-active vibration control by controlling the load connected between the terminals of the generator in the electromagnetic shock absorber. While performing the vibration control, the circuit always draw current from the shock absorber and the suspension remain dissipative, and the shock absorber takes no additional energy to perform the vibration control. The working principle and dynamics of the circuit has been analyzed and simulations were performed to validate the concept.

  9. An investigation of steady-state averaging for the single-inductor dual-output buck converter using Fourier analysis

    Microsoft Academic Search

    Ben Tsai; Olivier Trescases; Bruce Francis

    2010-01-01

    The SIDO converter is appealing in low-power applications requiring two independent supply voltages. The use of a single inductor significantly reduces the cost and size of the converter, however the complexity of the controller is greatly increased due to the inherent coupling of the two output voltages in continuous conduction mode. The accuracy of the traditional averaging technique is examined

  10. Active Load for Burn-in Test of Buck-Type DC-DC Converter with Ultra-Low Output Voltage

    Microsoft Academic Search

    K. I. Hwu

    2009-01-01

    In this paper, a nonisolated single-stage active load for burn-in test of the buck-type DC-DC converter with ultra-low output voltage is presented herein so as to realize energy recycling. The detailed illustration of this converter, together with some simulation experimental results, is provided to demonstrate the effectiveness of the proposed scheme. I. INTRODUCTION DC-DC converters have many advantages, such as

  11. A tapped-inductor buck-boost converter for a multi-DEAP generator energy harvesting system

    NASA Astrophysics Data System (ADS)

    Dimopoulos, Emmanouil; Munk-Nielsen, Stig

    2014-03-01

    Interest on Dielectric ElectroActive Polymer (DEAP) generators has aroused among scientists in recent years, due to the former ones' documented advantages against competing electromagnetic and field-activated technologies. Yet, the need for bidirectional energy flow under high step-up and high step-down voltage conversion ratios, accompanied by low-average but relatively high-peak currents, imposes great challenges on the design of the employed power electronic converter. On top of that, the shortage of commercially-available, high-efficient, high-voltage, low-power semiconductor devices limits the effective operational range of the power electronic converter. In this paper, a bidirectional tapped-inductor buck-boost converter is proposed, addressing high- efficient high step-up and high step-down voltage conversion ratios, for energy harvesting applications based on DEAP generators. The effective operational range of the converter is extended, by replacing its high-side switch with a string of three serialized MOSFETs, to accommodate the need for high-efficient high-voltage operation. Experiments conducted on a single DEAP generator - part of a quadruple DEAP generator energy harvesting system with all elements installed sequentially in the same circular disk with a 90° phase shift - validate the applicability of the proposed converter, demonstrating energy harvesting of 0.26 J, at 0.5 Hz and 60% delta- strain; characterized by an energy density of 1.25 J per kg of active material.

  12. A Bidirectional High-Power-Quality Grid Interface With a Novel Bidirectional Noninverted Buck Boost Converter for PHEVs

    SciTech Connect

    Onar, Omer C [ORNL

    2012-01-01

    Plug-in hybrid electric vehicles (PHEVs) will play a vital role in future sustainable transportation systems due to their potential in terms of energy security, decreased environmental impact, improved fuel economy, and better performance. Moreover, new regulations have been established to improve the collective gas mileage, cut greenhouse gas emissions, and reduce dependence on foreign oil. This paper primarily focuses on two major thrust areas of PHEVs. First, it introduces a grid-friendly bidirectional alternating current/direct current ac/dc dc/ac rectifier/inverter for facilitating vehicle-to-grid (V2G) integration of PHEVs. Second, it presents an integrated bidirectional noninverted buck boost converter that interfaces the energy storage device of the PHEV to the dc link in both grid-connected and driving modes. The proposed bidirectional converter has minimal grid-level disruptions in terms of power factor and total harmonic distortion, with less switching noise. The integrated bidirectional dc/dc converter assists the grid interface converter to track the charge/discharge power of the PHEV battery. In addition, while driving, the dc/dc converter provides a regulated dc link voltage to the motor drive and captures the braking energy during regenerative braking.

  13. Two phase interleaved buck converter for driving high power LEDs Szymon Bczkowski, Stig Munk-Nielsen

    E-print Network

    Munk-Nielsen, Stig

    for supplying high current, low voltage devices like microprocessors and they are now becoming a reasonable on the country. Two boost converters are paralleled to handle high input currents at low AC grid voltage topology converts this voltage to 30V DC providing galvanic isolation. DC link voltage on a Cdc capacitor

  14. Buck-boost converter with dual-mode control for battery charging

    SciTech Connect

    Ray, R. C.

    1985-08-20

    A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode. These instabilities are avoided in a flyback converter used for battery charging by using current control techniques to control current on the primary side of the converter during high-rate battery charging. During low-rate charging, normal voltage feedback from an output current sensing resistor is used as long as the converter operates in a discontinuous mode.

  15. Soft-Switching Zeta–Flyback Converter With a Buck–Boost Type of Active Clamp

    Microsoft Academic Search

    Bor-Ren Lin; Fang-Yu Hsieh

    2007-01-01

    This paper presents the system analysis, design consideration, and implementation of a soft-switching zeta-flyback converter to achieve zero-voltage switching (ZVS). In the proposed converter, the zeta and flyback topologies are adopted in the output side to achieve the following features: to share the power components in the transformer primary side, to achieve the partial magnetizing flux reset, and to share

  16. Unified Control Strategy Covering CCM and DCM for a Synchronous Buck Converter

    Microsoft Academic Search

    Dirk Hirschmann; Sebastian Richter; Christian Dick; Rik W. De Doncker

    2007-01-01

    In general, transfer functions of switch-mode converters are treated differently when operating in continuous-conduction mode (CCM) or discontinuous-conduction mode (DCM). This complicates the development of a control algorithm for a converter operating in both operating modes. To solve this problem, a control algorithm is developed, which is applicable for CCM and DCM. Since the developed control algorithm is based on

  17. A Novel High-Efficiency Battery Charger With a Buck Zero-Voltage-Switching Resonant Converter

    Microsoft Academic Search

    Ying-Chun Chuang; Yu-Lung Ke

    2007-01-01

    The high-frequency resonant converter has numerous well-known advantages over the traditional hard-switching converters. The most important advantage is that it offers a lower switching loss and a higher power density. Additionally, the soft-switching current waveform characterizes a lower electromagnetic interference (EMI). This study presents the circuit configuration with the least components to realize a highly efficient solar energy battery charger

  18. Duomode non-linear state space averaged SPICE model of a current mode buck converter

    Microsoft Academic Search

    J. E. Chen; F. D. Rodriguez

    1988-01-01

    Although most current-programmed converters are designed for steady-state continuous mode operation, transient and fault analysis require dual-mode (continuous\\/discontinuous) models. The popularity of SPICE (Simulation Program with Integrated Circuits Emphasis) has created a demand for nonlinear state space averaged SPICE converter models because execution times of brute-force SPICE models are impractical. The theory, evolution, and use of a fast, nonlinear, duo-mode

  19. A low-ripple fast-response CMOS integrated switching buck converter with dual-mode pulse-train\\/PWM control

    Microsoft Academic Search

    Feng Luo; Dongsheng Ma

    2008-01-01

    This paper presents a CMOS integrated switching buck converter with a dual-mode control scheme. A pulse-train (PT) control is employed for fast and smooth transient response, where four different pulse patterns are proposed to achieve optimal regulations at different transient operation scenarios. In addition, a high-frequency pulse-width modulation (PWM) control is adopted to ensure low output ripples in the steady

  20. Buck-boost converter with dual-mode control for battery charging

    Microsoft Academic Search

    1985-01-01

    A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode. These instabilities are avoided in

  1. A novel Dual-Mode synchronous high efficiency buck converter with Adaptive deadtime control

    Microsoft Academic Search

    Ya-Wu Chung; S. Rai Mahendra; Wan-Rone Liou; Chih-Yung Cheng

    2010-01-01

    A novel Dual-Mode Modulation Zero Current Detection (ZCD) & Adaptive deadtime architecture has been proposed in this paper that can be used in a DC to DC step-down switching regulator. The converter operates in the pulse width modulation (PWM) mode for heavy load conditions and in the pulse frequency modulation (PFM) mode for light load conditions. In both these operating

  2. Battery-utility interface using soft switched AC link buck boost converter

    Microsoft Academic Search

    Mahshid Amirabadi; Hamid A. Toliyat; William C. Alexander

    2009-01-01

    In this paper a novel soft switched high frequency AC link converter is proposed for use as a battery-utility interface. The proposed configuration uses 10 bi-directional switches interfacing with an AC link consisting of an inductor and a parallel capacitance. The capacitance produces soft turn off in all operating conditions, and turn on always occurs with zero voltage. Utility scale

  3. Closed-Form Critical Conditions of Subharmonic Oscillations for Buck Converters

    E-print Network

    Chung-Chieh Fang

    2012-03-26

    A general critical condition of subharmonic oscillation in terms of the loop gain is derived. Many closed-form critical conditions for various control schemes in terms of converter parameters are also derived. Some previously known critical conditions become special cases in the generalized framework. Given an arbitrary control scheme, a systematic procedure is proposed to derive the critical condition for that control scheme. Different control schemes share similar forms of critical conditions. For example, both V2 control and voltage mode control have the same form of critical condition. A peculiar phenomenon in average current mode control where subharmonic oscillation occurs in a window value of pole can be explained by the derived critical condition. A ripple amplitude index to predict subharmonic oscillation proposed in the past research has limited application and is shown invalid for a converter with a large pole.

  4. Control of power flow in a resonant DC-DC buck and boost converter

    Microsoft Academic Search

    I. Nagy; J. Hamar

    2000-01-01

    The paper contains a detailed analysis of the steady-state operation of the dual channel resonant DC-DC step up\\/down converter. The limits of the real operation have been marked out and the regions of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) have also been separated. Three kinds of power flow control methods are observed, but the application of a

  5. Feasibility of time-delay based frequency-control of a sliding-mode buck converter

    Microsoft Academic Search

    Benoit Labbe; David Chesneau; Bruno Allard; Xuefang Lin-Shi

    2011-01-01

    The step-down switch-mode DC\\/DC power supply is commonly used in power management of integrated circuits such as high performances processors and high speed memories. Sliding-mode-control appears to be one of the best way to control step-down switch-mode converter due to stringent transient performances required by next generation processor cores used in Smart-phones or Tablets. However sliding-mode’s free-running frequency has to

  6. 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

    2015-01-01

    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.

  7. A voltage-mode DC—DC buck converter with fast output voltage-tracking speed and wide output voltage range

    NASA Astrophysics Data System (ADS)

    Miao, Yang; Baixue, Zhang; Yun, Cao; Fengfeng, Sun; Weifeng, Sun

    2014-05-01

    A high switching frequency voltage-mode buck converter with fast voltage-tracking speed and wide output voltage range has been proposed. A novel error amplifier (EA) is presented to achieve a high DC gain and get high phase margin, including a resistor and capacitor net, a unit gain block and a high gain block. The investigated converter has been fabricated with GF 0.35 ?m CMOS process and can operate at 6 MHz with the output voltage range from 0.6 to 3.4 V. The experimental results show that the voltage-tracking speed can achieve 8.8 ?s/V for up-tracking and 6 ?s/V for down-tracking. Besides, the recovery time is less than 8 ?s while the load current suddenly changes 400 mA.

  8. Preventing transformer saturation in bi-directional dual active bridge buck-boost DC\\/DC converters

    Microsoft Academic Search

    Sangtaek Han; I. Munuswamy; D. Divan

    2010-01-01

    In switch-mode power electronic converters, DC offset of the magnetizing flux in the isolation transformer can cause saturation. In typical single-ended dc\\/dc converters, this is handled using a current loop which ensures that the average current in the winding is zero. For bi-directional dc\\/dc converters with active bridges on both sides, there exists a danger of impressing dc offsets from

  9. Single-inductor dual buck-boost output (SIDBBO) converter with adaptive current control mode (ACCM) and adaptive body switch (ABS) for compact size and long battery life in portable devices

    Microsoft Academic Search

    Ming-Hsin Huang; Ke-Horng Chen

    2009-01-01

    A single-inductor dual buck-boost output (SIDBBO) converter is proposed to provide compact size and long battery life to portable devices. The proposed adaptive current control mode (ACCM) reduces cross-regulation and power losses since ACCM adaptively controls inductor current for output regulating. Moreover, adaptive body switch (ABS) addresses potential leakage and latch-up, which occur when N-well bias vary with supply voltage.

  10. A low-cost BLDC motor drive using buck-boost converter for residential and commercial applications

    Microsoft Academic Search

    Rahul Khopkar; S. M. Madmi; Masoud HaJiaghajani; H. A. Tohya

    2003-01-01

    This paper presents a novel low-cost, highly efficient, reliable and compact motor drive topology for residential and commercial applications, such as building air conditioning, appliances, etc. The drives consist of a three-phase permanent magnet brushless DC (BLDC) motor, an AC-DC converter and a three-phase inverter containing six silicon-controlled rectifiers (SCRs). A microcontroller or a digital signal processor (DSP) is used

  11. Single inductor dual output dc-dc converter for space-limited or large input voltage variation systems

    Microsoft Academic Search

    Zaki Moussaoui; Jifeng Qin; Greg Miller

    2010-01-01

    The design of a Single Inductor Dual Output (SIDO) buck converter using two individual voltage mode control loops has been presented in this paper, and the limitation of using such control method has been indicated, then the control schemes for minimizing the cross regulation issue has been discussed. By using two separate control loops, the inductor energy is shared and

  12. Design of single-inductor dual-output switching converters with average current mode control

    Microsoft Academic Search

    Weiwei Xu; Xiaoting Zhu; Zhiliang Hong; Dirk Killat

    2008-01-01

    An average current mode controlled single-inductor dual-output (SIDO) buck converter is presented. The outputs are specified with 1.2 V\\/400 mA and 1.8 V\\/200 mA. The proposed decoupling model helps to analyze the multi-loop system and to design the on-chip compensators. The converter has been fabricated in 0.25-mum mixed-signal process. Simulation and measurement results confirm the proposed analysis. The power efficiency

  13. Peak power tracking for a solar buck charger

    E-print Network

    Cohen, Jeremy Michael, M. Eng. Massachusetts Institute of Technology

    2010-01-01

    This thesis discusses the design, implementation, and testing of a buck converter with peak power tracking. The peak power tracker uses a perturb and observe algorithm to actively track the solar panel's peak power point ...

  14. 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

  15. Output voltage switching noise peaks and utility AC input harmonic current characteristics of delta-sigma modulated AC-DC converter with boost-buck circuit topologies

    Microsoft Academic Search

    Atsushi Hirota; Sang-Pil Mun; Soon-Kurl Kwon; M. Nakaoka

    2009-01-01

    A high frequency carrier PWM regulator used for various types of switch-mode power converters are based on the digital or analog signal comparison processing. The voltage-mode or current-mode PWM strategies due to comparison signal processing between voltage\\/current reference and periodic carrier signals cause the switching noise peaks dependent on the multiple numbers of carrier signal frequency. In general, the switching

  16. Inherent DCM operation of the asymmetrical interleaved dual buck-boost

    Microsoft Academic Search

    Roberto Giral; Eliana Arango; Javier Calvente; Luis Martinez-Salamero

    2002-01-01

    A fifth order DC\\/DC converter based on the asymmetric connection of two buck-boost cells with complementary activation of their switches is presented. In steady state, the new converter inherently operates in discontinuous conduction mode (DCM). With a duty cycle greater than 38%, the asymmetrical interleaved dual buck-boost (AIDBB) behaves like an inverting boost converter. The AIDBB exhibits some benefits of

  17. Converter

    NSDL National Science Digital Library

    2010-01-01

    In this activity, students enter in a fraction and the applet calculates the decimal representation of the fraction and vice versa. This activity allows students to explore converting fractions from decimals and from decimals to fractions. This activity includes supplemental materials, including background information about the topics covered, a description of how to use the application, and exploration questions for use with the java applet.

  18. Water Quality Monitoring in the Buck Creek Watershed and Facilitation of Buck Creek Watershed Partnership

    E-print Network

    Gregory, L.; Dyer, P.

    The “Water Quality Monitoring in the Buck Creek Watershed and Facilitation of Buck Creek Watershed Partnership” project was developed to continue water quality monitoring on Buck Creek and to continue to engage watershed stakeholders during the Buck...

  19. 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.

  20. Topological Development and Operational Analysis of Buck-Boost Current Source Inverters for Energy Conversion Applications

    Microsoft Academic Search

    P. C. Loh; P. C. Tan; F. Blaabjerg; T. K. Lee

    2006-01-01

    In this paper, two three-phase buck-boost current-source inverters (CSIs) are designed for use in general energy conversion applications where the input source voltage varies widely. The inverters are developed by first identifying characteristic modular features of a traditional CSI before cautiously integrating the noted features to a buck-boost converter and a single-ended primary inductance converter (SEPIC) to develop two extended

  1. Buck Buffer Leslie Vosshall

    E-print Network

    Buck Buffer Leslie Vosshall Axel Lab 5/7/1998 For high stringency hybridization of library screens.5 M Sodium Phosphate pH 7.3 1% BSA 4% SDS For 1 liter: Prewarm about 800 ml distilled water to 65 Phosphate Dibasic: 103.21 g (Heptahydrate, FW=268.07) **OR** 54.66 g (Anhydrous, FW=141.96) Mix until

  2. 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

  3. Coupled Dual Interleaved Flyback Converter for High Input Voltage Application

    E-print Network

    Lehman, Brad

    -Bridge [5,6], and buck-boost mode topologies, such as dual Flyback [9,10]. More recently, there are newly for buck mode topologies. Historically, magnetic integration is utilized for Forward converters [1Coupled Dual Interleaved Flyback Converter for High Input Voltage Application Ting Qian, Brad

  4. 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.

  5. 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.

  6. Conference James F.Buckli

    SciTech Connect

    None

    2008-02-07

    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

  7. Buck Creek River Flow Analysis

    Microsoft Academic Search

    Yasas Dhanapala; Elizabeth George; John Ritter

    2009-01-01

    Buck Creek flowing through Springfield Ohio has a number of low-head dams currently in place that cause safety issues and sometimes make it impossible for recreational boaters to pass through. The safety issues include the back eddies created by the dams that are known as drowning machines and the hydraulic jumps. In this study we are modeling the flow of

  8. 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

  9. Bucking Trends: Expanding the Arts

    ERIC Educational Resources Information Center

    Levin, Kathi R.

    2008-01-01

    The arts and music have been unintended victims of the No Child Left Behind Act. Several reports point to sharp reductions in student access to K-12 arts education, yet some school districts nationwide have managed to buck the trend. These districts, in communities rural through urban, are systemically embedding the arts at the core of teaching…

  10. Abstract--The implementation of a low-voltage Zero-Voltage-Switching Quasi-Square-Wave (ZVS-QSW) buck

    E-print Network

    Ng, Wai Tung

    -QSW) buck converter capable of meeting the future challenges of low- voltage VRMs is presented a dual-mode configuration. An experimental DVS test-bench was developed using a state-of- the-art Xilinx hard-switched synchronous Buck converters [1]: 2 2 ( )sw turn on turn off p in in out r sP P P C V V I

  11. Transformerless dc-Isolated Converter

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.

    1987-01-01

    Efficient voltage converter employs capacitive instead of transformer coupling to provide dc isolation. Offers buck/boost operation, minimal filtering, and low parts count, with possible application in photovoltaic power inverters, power supplies and battery charges. In photovoltaic inverter circuit with transformerless converter, Q2, Q3, Q4, and Q5 form line-commutated inverter. Switching losses and stresses nil because switching performed when current is zero.

  12. Series Connected Buck-Boost Regulator

    NASA Technical Reports Server (NTRS)

    Birchenough, Arthur G. (Inventor)

    2006-01-01

    A Series Connected Buck-Boost Regulator (SCBBR) that switches only a fraction of the input power, resulting in relatively high efficiencies. The SCBBR has multiple operating modes including a buck, a boost, and a current limiting mode, so that an output voltage of the SCBBR ranges from below the source voltage to above the source voltage.

  13. Controlled doe exposure as biostimulation of buck rabbits

    Microsoft Academic Search

    R. Rodríguez-De Lara; J. Noguez-Estrada; R. Rangel-Santos; J. G. García-Muñiz; P. A. Martínez-Hernández; M. Fallas-López; E. Maldonado-Siman

    2010-01-01

    Female exposure of males could be a low-cost biostimulation option that benefits AI in commercial rabbit operations by improving buck rabbits reproductive performance. The objective of the study was to evaluate exposure of buck rabbits to females as a biostimulation option to improve reproductive potential. Treatments were: exposure (biostimulated) or not (control) of bucks to does. Bucks were New Zealand

  14. Buck Creek River Flow Analysis

    NASA Astrophysics Data System (ADS)

    Dhanapala, Yasas; George, Elizabeth; Ritter, John

    2009-04-01

    Buck Creek flowing through Springfield Ohio has a number of low-head dams currently in place that cause safety issues and sometimes make it impossible for recreational boaters to pass through. The safety issues include the back eddies created by the dams that are known as drowning machines and the hydraulic jumps. In this study we are modeling the flow of Buck Creek using topographical and flow data provided by the Geology Department of Wittenberg University. The flow is analyzed using Hydraulic Engineering Center - River Analysis System software (HEC-RAS). As the first step a model of the river near Snyder Park has been created with the current structure in place for validation purposes. Afterwards the low-head dam is replaced with four drop structures with V-notch overflow gates. The river bed is altered to reflect plunge pools after each drop structure. This analysis will provide insight to how the flow is going to behave after the changes are made. In addition a sediment transport analysis is also being conducted to provide information about the stability of these structures.

  15. Landowners lead successful Buck Creek restoration

    E-print Network

    Boutwell, Kathryn S.

    2012-01-01

    26 tx H2O Fall 2012 Story by Kathryn S. Boutwell Landowners in the Buck Creek watershed in the Texas Panhandle were the driving force behind the successful restoration of the watershed and its removal from the Texas Commission on Environ... the Buck Creek watershed as Texas? #25;#22;h water quality restoration success story. ?#31;e removal of Buck Creek from the impaired list is a direct result of the e#27;orts of local landowners,? said Phyllis Dyer, research associate at the Texas A...

  16. Multiple port DC DC converter for spacecraft Power Conditioning Unit

    Microsoft Academic Search

    Olivier Mourra; Arturo Fernandez; Ferdinando Tonicello; Sven Landstroem

    2012-01-01

    In a satellite, the main function of a Power Conditioning Unit (PCU) is to manage the energy coming from several power sources (usually solar arrays and battery) and to deliver it continuously to the users in an appropriate form during the overall mission. The objective of this paper is to present an electronic switching DC-DC converter called Buck-Buck-Boost Regulator (B³R)

  17. Design-Oriented Analysis and Performance Evaluation of Buck PFC Front End

    Microsoft Academic Search

    Laszlo Huber; Liu Gang; M. M. Jovanovic

    2010-01-01

    In universal-line ac\\/dc converters that require power factor correction (PFC), maintaining a high efficiency across the entire line and load ranges poses a major challenge. Typically, a boost PFC front end exhibits 1%-3% lower efficiency at 100-V line compared to that at 230-V line. It is shown in this paper that a buck PFC front end with an output voltage

  18. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Zhang, De-Xin; AbdulMazid, M. D.; Attia, John O.; Kankam, Mark D. (Technical Monitor)

    2001-01-01

    In this work, several DC-DC converters were designed and built. The converters are Buck Buck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the Buck Buck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buck converter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dc converter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dc converter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dc converter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25.97 MeV-square cm/mg. This might be due to fact that the device is radiation hardened.

  19. Characteristics of the multiple-input DC-DC converter

    Microsoft Academic Search

    H. Matsuo; T. Shigemizu; F. Kurokawa; N. Watanabe

    1993-01-01

    A multiple-input DC-DC converter is proposed for realizing a clean electric power generation system. The two-input buck-boost type converter is analyzed, and the static and dynamic characteristics are clarified theoretically and are confirmed by experiment

  20. Bifurcation in a dual channel resonant DC-DC converter

    Microsoft Academic Search

    IstvAn Nagy; Octavian Dranga

    2000-01-01

    The paper reports first time subharmonic, quasiperiodic and chaotic operation in one member of a double channel resonant DC-DC power converter family. The converters of this family can operate both in symmetrical and in asymmetrical mode. The study presented in the paper is restricted to the buck configuration in symmetrical operation. A brief summary of the configuration and basic operation

  1. Dual channel DC-DC converter in continuous conduction mode

    Microsoft Academic Search

    I. Nagy; J. Hamar; K. R. Jardan

    1999-01-01

    The paper presents the CCM (continuous conduction mode) operation of the dual channel resonant DC-DC step down (buck) converter. However, as a result of certain limitations, sometimes the converter cannot be operated in CCM at all. The paper presents the mathematical analysis of CCM operation, explores the basic relations between input, output and control variables for the more general asymmetric

  2. A High-Efficiency, Dual-Mode, Dynamic, Buck-Boost Power Supply IC for Portable Applications

    Microsoft Academic Search

    Biranchinath Sahu; Gabriel A. Rincón-mora

    2005-01-01

    Integrated power supplies are critical building blocks in state-of-the-art portable applications, where they efficiently and accurately transform a battery supply into various regulated voltages, as required by their loads. This paper presents a novel low voltage, dual-mode, buck-boost converter IC targeted for dynamic supplies of linear RF power amplifiers (PAs) in wireless handsets. Maintaining high efficiency of the converter over

  3. CMOS-Compatible SOI MESFETS for Radiation-Hardened DC-to-DC Converters

    NASA Technical Reports Server (NTRS)

    Thornton, Trevor; Lepkowski, William; Wilk, Seth

    2013-01-01

    A radiation-tolerant transistor switch has been developed that can operate between 196 and +150 C for DC-to-DC power conversion applications. A prototype buck regulator component was demonstrated to be performing well after a total ionizing dose of 300 krad(Si). The prototype buck converters showed good efficiencies at ultra-high switching speeds in the range of 1 to 10 MHz. Such high switching frequency will enable smaller, lighter buck converters to be developed as part of the next project. Switching regulators are widely used in commercial applications including portable consumer electronics.

  4. Women in History--Pearl Buck: An Advocate for Women and Children

    ERIC Educational Resources Information Center

    Watts, Lynette

    2008-01-01

    This article profiles Pearl Buck, an advocate for women's rights and minority children, an author of Chinese history, and a pioneer in many ways. Buck established the Welcome House in 1949 in order to help unadoptable children find families (Conn, 1996). In 1964, Buck founded the Pearl S. Buck Foundation, now Pearl S. Buck International, which…

  5. Design of anti-jamming current-sensing circuit for current-mode buck regulator

    NASA Astrophysics Data System (ADS)

    Bing, Yuan; Xinquan, Lai; Yanming, Li; Qiang, Ye; Xinzhang, Jia

    2009-04-01

    A novel anti-jamming integrated CMOS current-sensing circuit for current-mode buck regulators is presented. Based on the widely-used traditional current-sensing structure, anti-jamming performance is improved significantly by adding on-chip capacitors and one-shot circuit. Also the transient response is faster through the introduction of current offset. The circuit is concise, simple to implement and suits for SoC applications with single power supply. A dual-output current-mode DC-DC buck converter with proposed structure has been fabricated with a 0.5 ?m CMOS process for validation. In the 2.5-5.5 V input range, the two channels work steadily in the load current range of 0-600 mA. And the measured maximum efficiency is up to 96%.

  6. Bacterial Monitoring for the Buck Creek Watershed

    E-print Network

    The “Bacterial Monitoring for the Buck Creek Watershed” project was developed in response to the creek’s listing on the Texas Water Quality Inventory and 303(d) List due to a bacterial impairment and subsequent total maximum daily load (TMDL...

  7. 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

  8. Special family of PWM-based sliding-mode voltage controllers for basic DC–DC converters in discontinuous conduction mode

    Microsoft Academic Search

    S.-C. Tan; Y. M. Lai; C. K. Tse; L. Martinez-Salamero

    2007-01-01

    A family of fixed-frequency pulsewidth-modulation-based sliding-mode voltage controllers for DC-DC converters operating in the discontinuous conduction mode is proposed. The proposed topology is developed for buck, boost and buck-boost converters. Preliminary verification and evaluation of these controllers are performed through computer simulations using precise models of the systems. DC-DC converters can operate in either continuous conduction mode (CCM) or discontinuous

  9. The application of standardized control and interface circuits to three dc to dc power converters.

    NASA Technical Reports Server (NTRS)

    Yu, Y.; Biess, J. J.; Schoenfeld, A. D.; Lalli, V. R.

    1973-01-01

    Standardized control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the series-switching buck regulator, and the pulse-modulated parallel inverter. The two-loop ASDTIC regulation control concept was implemented by using a common analog control signal processor and a novel digital control signal processor. This resulted in control circuit standardization and superior static and dynamic performance of the three dc-to-dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

  10. 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

  11. Laboratory and workplace assessments of rivet bucking bar vibration emissions.

    PubMed

    McDowell, Thomas W; Warren, Christopher; Xu, Xueyan S; Welcome, Daniel E; Dong, Ren G

    2015-04-01

    Sheet metal workers operating rivet bucking bars are at risk of developing hand and wrist musculoskeletal disorders associated with exposures to hand-transmitted vibrations and forceful exertions required to operate these hand tools. New bucking bar technologies have been introduced in efforts to reduce workplace vibration exposures to these workers. However, the efficacy of these new bucking bar designs has not been well documented. While there are standardized laboratory-based methodologies for assessing the vibration emissions of many types of powered hand tools, no such standard exists for rivet bucking bars. Therefore, this study included the development of a laboratory-based method for assessing bucking bar vibrations which utilizes a simulated riveting task. With this method, this study evaluated three traditional steel bucking bars, three similarly shaped tungsten alloy bars, and three bars featuring spring-dampeners. For comparison the bucking bar vibrations were also assessed during three typical riveting tasks at a large aircraft maintenance facility. The bucking bars were rank-ordered in terms of unweighted and frequency-weighted acceleration measured at the hand-tool interface. The results suggest that the developed laboratory method is a reasonable technique for ranking bucking bar vibration emissions; the lab-based riveting simulations produced similar rankings to the workplace rankings. However, the laboratory-based acceleration averages were considerably lower than the workplace measurements. These observations suggest that the laboratory test results are acceptable for comparing and screening bucking bars, but the laboratory measurements should not be directly used for assessing the risk of workplace bucking bar vibration exposures. The newer bucking bar technologies exhibited significantly reduced vibrations compared to the traditional steel bars. The results of this study, together with other information such as rivet quality, productivity, tool weight, comfort, worker acceptance, and initial cost can be used to make informed bucking bar selections. PMID:25381185

  12. Interleaved boost-flyback converter with boundary conduction mode for power factor correction

    Microsoft Academic Search

    Bor-Ren Lin; Chia-Hung Chao; Chih-Cheng Chien

    2011-01-01

    This paper presents a new interleaved pulse-width modulation (PWM) boost-flyback converter to achieve power factor correction (PFC) and regulate DC bus voltage. The adopted boost-flyback converter has a high voltage conversion ratio to overcome the limit of conventional boost or buck-boost converter with narrow turn-off period. The proposed converter has wide turn-off period compared with a conventional boost converter. Thus

  13. The Series Connected Buck Boost Regulator Concept for High Efficiency Light Weight DC Voltage Regulation

    NASA Technical Reports Server (NTRS)

    Birchenough, Arthur G.

    2003-01-01

    Improvements in the efficiency and size of DC-DC converters have resulted from advances in components, primarily semiconductors, and improved topologies. One topology, which has shown very high potential in limited applications, is the Series Connected Boost Unit (SCBU), wherein a small DC-DC converter output is connected in series with the input bus to provide an output voltage equal to or greater than the input voltage. Since the DC-DC converter switches only a fraction of the power throughput, the overall system efficiency is very high. But this technique is limited to applications where the output is always greater than the input. The Series Connected Buck Boost Regulator (SCBBR) concept extends partial power processing technique used in the SCBU to operation when the desired output voltage is higher or lower than the input voltage, and the implementation described can even operate as a conventional buck converter to operate at very low output to input voltage ratios. This paper describes the operation and performance of an SCBBR configured as a bus voltage regulator providing 50 percent voltage regulation range, bus switching, and overload limiting, operating above 98 percent efficiency. The technique does not provide input-output isolation.

  14. Mathematical simulation of power conditioning systems. Volume 3. Simulation of elementary units. Results for boost, buck, buck-boost, shunt PWM. Final report

    Microsoft Academic Search

    R. Prajoux; J. Mazankine

    1976-01-01

    Results are presented of the hybrid simulation of elementary power conditioning units buck, boost, buck-boost and shunt PWM. For boost, buck and buck-boost, two operational modes were investigated: continuous and discontinuous conduction. Continuous conduction leads to bad performance of the basic unit and to a complicated correction network independent of current operating point, whereas discontinuous conduction provides for normal performance

  15. 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.

  16. 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.

  17. Caitlin Buck's Publication List November 2010

    E-print Network

    Oakley, Jeremy

    of the calibration curve for radiocarbon dating. Bayesian Analysis, 1(2), 265­288. [11] O'Hagan A., Buck C). A Bayesian approach to the estimation of radiocarbon calibration curves: the IntCal09 method- ology. Radiocarbon, 51(4), 1151­1164. [2] Reimer P.J., Baillie M.G.L., Bard E., Bayliss A., Beck J.W., Blackwell P

  18. Robust Step-up DC\\/AC conversion with a Full-Bridge Non-Inverting Buck-Boost

    Microsoft Academic Search

    Domingo Biel; Enric Fossas; Josep M. Olm

    2007-01-01

    The substitution of the original switches by a full-bridge in a non-inverting buck-boost converter results in an inverter capable of performing step-down and step-up tasks under sliding mode control. Furthermore, semi-infinite programming techniques are used to minimize power loses while preventing control action saturation. The performance of the inverter is shown to be robust in front of load perturbations. The

  19. Zero-voltage switching in high frequency power converters using pulse width modulation

    Microsoft Academic Search

    C. P. Henze; H. C. Martin; D. W. Parsley

    1988-01-01

    A zero-voltage switching technique is described that utilizes a resonant transition during a short but finite switching interval. This zero-voltage resonant-transition (ZVRT) switching technique can be applied to conventional buck, boost, and buck-boost power converter topologies that operate with a constant switching frequency and use pulsewidth modulation for output control. Since frequency-dependent losses are greatly reduced in the power transistors,

  20. Improving Benders Decomposition to Solve the Tree-Bucking Problem

    E-print Network

    Ferland, Jacques A.

    forest units of minimal dimension. Each stand is a homogeneous unit containing trees of the same speciesImproving Benders Decomposition to Solve the Tree-Bucking Problem Sylvie Roussel, D´epartement d level of decision to select the proper bucking (crosscutting) rule for each stand and a second level

  1. Continuous-Time Digital Signal Processing Based Controller for High-Frequency DC-DC Converters

    E-print Network

    Prodiæ, Aleksandar

    .com, prodic@power.utoronto.ca Abstract- This paper introduces a digital dual-mode controller for low is demonstrated on an experimental 5 V-to- 2V, 400 kHz, 2.5 W buck converter that recovers voltage in the timeContinuous-Time Digital Signal Processing Based Controller for High-Frequency DC-DC Converters

  2. 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 ...

  3. On-chip current sensing for monolithic buck LED driver

    E-print Network

    Penn, Alexander A

    2013-01-01

    This thesis explores and analyzes two different options for on-chip sensing and regulating current for a buck LED driver, as compared to a common external solution. With the rise of LED use in common lighting applications, ...

  4. Operation of buck regulator with ultra-low input voltage

    E-print Network

    Harris, Cory Angelo

    2014-01-01

    Based on the LTC3621 and LTC3624, the designed buck regulator proposed in this thesis aims to lower the allowed input voltage and increase efficiency compared to the original part without making significant changes to ...

  5. Successful pregnancies with directional freezing of large volume buck semen

    Microsoft Academic Search

    H. Gacitua; A. Arav

    2005-01-01

    Artificial insemination with frozen-thawed buck semen shows variable results which depend on many factors related to semen quality and the cryopreservation processing. We conducted experiments based on a new freezing method, directional freezing, of large volumes (8ml). In the first experiment semen from three Saanen bucks, ages 1–2-years-old and genetically selected for milk improvement, was frozen individually. Two to three-years-old

  6. Modeling, analysis and design for hybrid power systems with dual-input DC\\/DC converter

    Microsoft Academic Search

    Yan Li; Xinbo Ruan; Dongsheng Yang; Fuxin Liu

    2009-01-01

    Hybrid power systems derive power simultaneously from several renewable energy sources and deliver power continuously to the load. For such systems, the use of a multiple-input converter (MIC) has the advantage of simpler circuit design and lower cost, compared to the conventional use of several single-input converters. Taking dual-input Buck converter as the example in this paper, a new power

  7. A 1.2A 2MHz tri-mode Buck-Boost LED driver with feed-forward duty cycle correction

    Microsoft Academic Search

    S. Bang; D. Swank; A. Rao; W. McIntyre; Q. Khan; P. K. Hanumolu

    2010-01-01

    A flash LED Buck-Boost driver employs a dual duty cycle control and feed-forward duty cycle correction to achieve high efficiency over the entire Li-On battery voltage range of 3.0 to 5.2V. Fabricated in a 0.5?m CMOS process, the converter uses an external 1?H inductor and a 10?F capacitor and operates at 2MHz switching frequency. The measured peak efficiency is 83%

  8. Wrongs of 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 The Kallikak myth Buck vs. Bell was based on the myth that genetically flawed families could be identified and eliminated.

  9. 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.

  10. 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.

  11. Regulation of a lightweight high efficiency capacitator diode voltage multiplier dc-dc converter

    NASA Technical Reports Server (NTRS)

    Harrigill, W. T., Jr.; Myers, I. T.

    1976-01-01

    A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.

  12. Regulation of a lightweight high efficiency capacitor diode voltage multiplier dc-dc converter

    NASA Technical Reports Server (NTRS)

    Harrigill, W. T., Jr.; Myers, I. T.

    1976-01-01

    A method for the regulation of a capacitor diode voltage multiplier dc-dc converter has been developed which has only minor penalties in weight and efficiency. An auxiliary inductor is used, which only handles a fraction of the total power, to control the output voltage through a pulse width modulation method in a buck boost circuit.

  13. 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

  14. 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

  15. 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

  16. Buck family pedigree, still image with audioSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck>trial Following the trial of Buck vs. Bell, a pedigree chart was created displaying the evidence that had been presented to the court. In the first line the first generation is shown Â? Addy Emmitt or Emma Buck. In the second generation, Carrie Buck, the woman eventually sterilized, and in the third generation Vivian Alice Elaine Buck, born in 1924, tested at 7 months to show "backwardness." The dotted lines show the pedigree of people who are illegitimate, whose parents were not married. The Fs mark feeble-mindedness in all three generations in the Buck family. This pedigree shows the evidence presented to the court, and later to the world, to justify the result, in the case of Buck vs. Bell.

  17. Electrolytic capacitor-less, non-isolated PFC converter for high-voltage LEDs driving

    Microsoft Academic Search

    Myunghyo Ryu; Juwon Baek; Jonghyun Kim; Sungwoo Park; Heunggeun Kim

    2011-01-01

    This paper introduces electrolytic capacitor- less, non-isolated power factor corrected converters for high-voltage LEDs driving. To increase lifetime of the power supply, electrolytic capacitor is substituted to small polyester film capacitor and to insure input power factor(PF) higher than 0.9, conventional Boost and Buck- Boost PFC converters are chosen to drive high voltage LEDs driving due to its simplicity and

  18. Soft-switching interleaved bidirectional DC-DC converter for Advanced Vehicle Applications

    Microsoft Academic Search

    Dong-Gyu Lee; Nam-Ju Park; Dong-Seok Hyun

    2008-01-01

    This paper proposes soft-switching interleaved bidirectional DC-DC converter suitable for advanced vehicle Applications. The proposed converter integrates interleaved synchronous buck and ZVT-cell with a single resonant inductor. ZVS is guaranteed with wide load range in CCM as well as wide output voltage range by current injection method. Also, switching losses and reverse recovery effects can be minimized. In addition, it

  19. A digitally controlled PWM\\/PSM dual-mode DC\\/DC converter

    Microsoft Academic Search

    Zhen Shaowei; Zhang Bo; Luo Ping; Hou Sijian; Ye Jingxin; Ma Xiao

    2011-01-01

    A digitally controlled pulse width modulation\\/pulse skip modulation (PWM\\/PSM) dual-mode buck DC\\/DC converter is proposed. Its operation mode can be automatically chosen as continuous conduction mode (CCM) or discontinuous conduction mode (DCM). The converter works in PSM at DCM and in 2 MHz PWM at CCM. Switching loss is reduced at a light load by skipping cycles. Thus high conversion

  20. Topological variations of the inverse dual converter for high power DC-DC applications

    Microsoft Academic Search

    M. Ehsani; L. Laskai; M. O. Bilgic

    1990-01-01

    DC to DC power converter topologies that are suitable for high-density, high-power supplies are presented. Topological variations on the basic inverse dual converter (IDC) circuit, such as the coupled transformer and the multiphase and multipulse derivation of the single-phase IDC, are analyzed, and simulation results are discussed. The topologies have most of the IDC features, such as buck-boost operation, bidirectional

  1. Bookmark Converter

    NSDL National Science Digital Library

    Broding, Magnus.

    This windows utility enables user to convert their bookmarks from Netscape Navigator to Internet explorer and vice versa. It is small, fast, and simple to use. The latest version has been tested up to Netscape 4.6 and IE 5.0. Bookmark Converter is shareware and can be registered for $8.

  2. Smell and Taste: The Chemical Senses Linda B. Buck

    E-print Network

    Ulanovsky, Nachum

    Back 32 Smell and Taste: The Chemical Senses Linda B. Buck WE ARE CONTINUOUSLY bombarded by molecules released into our environment. Through the senses of smell and taste these molecules provide us neuroepithelium in the back of the nasal cavity. The sensory cells of the mouth that sense taste P.626 stimuli

  3. "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…

  4. 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…

  5. 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

  6. Show your Aggie Pride with the Aggie Bucks

    E-print Network

    be waived if student opens the account at a Bryan-College Station banking location and enrolls in online the clock account access with Wells Fargo Online® Banking For more information about the Aggie Bucks statements. Information contained in this document is subject to change. © 2011 Wells Fargo Bank, N.A. All

  7. Zero-voltage switching technique in dc/dc converters

    NASA Astrophysics Data System (ADS)

    Liu, Kwang-Hwa; Lee, Fred C. Y.

    1990-07-01

    A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buck converter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.

  8. Successful pregnancies with directional freezing of large volume buck semen.

    PubMed

    Gacitua, H; Arav, A

    2005-02-01

    Artificial insemination with frozen-thawed buck semen shows variable results which depend on many factors related to semen quality and the cryopreservation processing. We conducted experiments based on a new freezing method, directional freezing, of large volumes (8 ml). In the first experiment semen from three Saanen bucks, ages 1-2-years-old and genetically selected for milk improvement, was frozen individually. Two to three-years-old Saanen females (n = 164) were synchronized with controlled internal drug release (CIDR), pregnant mare serum gonadotrophin (PMSG) and prostaglandin. Double cervical inseminations were performed with frozen-thawed semen and fresh semen as control. In the second experiment we used pooled, washed frozen semen to examine the effect of washed seminal plasma. The motility after washing was 80-90% and after thawing was 55-65% for all bucks. The sperm concentration increased with the collections and the advance into the breeding season from 1.9 x 10(9) to 4.4 x 10(9) cell/ml average. Two inseminations were carried out at 8h intervals. The first insemination was performed at 32 h after CIDR withdrawal with fresh and frozen-thawed semen. Pregnancy rates were assessed by ultrasonography conducted 40 and 90 days post-insemination (from three bucks). Results were 58, 67, 50% with fresh semen, and for frozen semen were 33, 37 and 53%; these results were significantly different in one of the three bucks (P < 0.005). In the second experiment with pooled, washed semen the pregnancy rate was 41.6%, which compared with the average results of the frozen semen in the first experiment 38.9% no significant difference was found. We conclude that freezing buck semen in large volumes (8 ml) is possible. Cryobanking of buck semen will facilitate a genetic breeding program in goats and preservation of biodiversity. Washed semen did not improve the fertility of the semen when Andromed bull extender is used. PMID:15629809

  9. 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.

  10. Maximum Power Extraction from a Small Wind Turbine Emulator using a DC - DC Converter Controlled by a Microcontroller

    Microsoft Academic Search

    M. T. Iqbal; J. E. Quaicoe

    2006-01-01

    An isolated small wind turbine emulator based on a separately excited DC motor is developed to emulate and evaluate the performance of a small wind turbine using different control strategies. The test rig consists of a 3HP separately excited DC motor coupled to a synchronous generator. A dump load is connected to the generator through a buck-boost converter controlled by

  11. A fast response adaptive DC–DC switching converter using on–chip dual–loop one–cycle control

    Microsoft Academic Search

    Dongsheng Ma; Wing-Hung Ki; Chi-Ying Tsui

    2002-01-01

    A switching buck converter with variable output voltage using one-cycle control is presented. The control loop employs dc level shifting technique to eliminate the use of negative supply voltage. This controller accommodates both continuous and discontinuous conduction operation, and improves on existing open loop designs by adding a feedback loop for tight output voltage control. It was fabricated using a

  12. Magnetorheological converters

    SciTech Connect

    Zal'tsgendler, E.A.; Kolomentsev, A.V.; Kordonskii, V.I.; Madorskii, L.S.

    1986-04-01

    The authors study the problems of constructing an electrohydraulic converter functioning based on the magnetoheological effect: the magnetorheological throttle (MR throttle). Requirements are listed that must be taken into account in developing the MR throttle. The paper attempts to calculate the flow-rate characteristics of the MR throttle. The rheological equation which describes sufficiently the mechanical properties of the magnetoheological suspensions is presented. The paper examines the calculation of the magnetic inductor for the example of a toroidal core with a gap, which simultaneously functions as the slot throttling channel. The use of the designs described enabled the development of bridge converters, which have a flat amplitude-frequency characteristic in the range 200-250 Hz and which have good energy indicators. Typical experimental logarithmic amplitude-frequency and phase-frequency characteristics of a bridge converter are shown.

  13. 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.

  14. 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.

  15. Measurement Converter

    NSDL National Science Digital Library

    Many online calculators require a Java-capable browser. Here's one that doesn't, and will perform over 500 different unit conversions for distance, area, volume, mass, speed, temperature, pressure, energy, power, force, etc. And when you convert, say, 5 kilometers to miles, you not only get the conversion result, but a wealth of related measurements and sample conversions.

  16. 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.

  17. Hybrid Voltage-Multipliers Based Switching Power Converters

    NASA Astrophysics Data System (ADS)

    Rosas-Caro, Julio C.; Mayo-Maldonado, Jonathan C.; Vazquez-Bautista, Rene Fabian; Valderrabano-Gonzalez, Antonio; Salas-Cabrera, Ruben; Valdez-Resendiz, Jesus Elias

    2011-08-01

    This work presents a derivation of PWM DC-DC hybrid converters by combining traditional converters with the Cockcroft-Walton voltage multiplier, the voltage multiplier of each converter is driven with the same transistor of the basic topology; this fact makes the structure of the new converters very simple and provides high-voltage gain. The traditional topologies discussed are the boost, buck-boost, Cuk and SEPIC. They main features of the discussed family are: (i) high-voltage gain without using extreme duty cycles or transformers, which allow high switching frequency and (ii) low voltage stress in switching devices, along with modular structures, and more output levels can be added without modifying the main circuit, which is highly desirable in some applications such as renewable energy generation systems. It is shown how a multiplier converter can become a generalized topology and how some of the traditional converters and several state-of-the-art converters can be derived from the generalized topologies and vice-versa. All the discussed converters were simulated, additionally experimental results are provided with an interleaved multiplier converter.

  18. Bounding the output error in a buck power converter using perturbation theory

    E-print Network

    Politècnica de Catalunya, Universitat

    . As a consequence of the switch- ing action, chattering, high order harmonic distortion and nonlinear phenomena appear. The latter can be dealt with control techniques [1], while chattering and harmonic dis- tortion, inherent to switching, can be reduced, but not avoided, using fixed switching frequency. To achieve

  19. A Dual-Supply Buck Converter with Improved Light-Load Efficiency

    E-print Network

    Zhang, Chao

    2012-07-16

    Mode ............................................................................................ 36 3.1.4 Mode-Hopping ...................................................................................... 37 3.1.5 Gate Drive... ........................................................................................... 48 4.3 PWM Mode and Control Method ....................................................................... 49 4.4 Current Sensing Technique ................................................................................ 57 4.5 Switched...

  20. Regenerative Braking for an Electric Vehicle Using Ultracapacitors and a Buck-Boost Converter

    E-print Network

    Catholic University of Chile (Universidad Católica de Chile)

    at the Catholic University of Chile. Introduction Ultracapacitors are a new technology that allows to store 20 University of Chile Casilla 306, Correo 22 Santiago, Chile Phone 56-2-686-4281 Fax 56-2-552-2563 e

  1. Nested Hysteretic Current-mode Single-inductor Multiple-output (SIMO) Boosting Buck Converter

    E-print Network

    Rincon-Mora, Gabriel A.

    after every packet in discontinuous-conduction mode (DCM). Because LC complex-conjugate poles reduce to one left-half-plane pole in DCM, some researchers emulate DCM operation when load power is high by momentarily short-circuiting the inductor after each packet. Under these pseudo-DCM (PDCM) conditions [5], i

  2. Design and Implementation of Fully Integrated Digitally Controlled Current-Mode Buck Converter

    Microsoft Academic Search

    Man Pun Chan; Philip K. T. Mok

    2011-01-01

    Digital current-mode control is a dual-loop control which potentially results in a better transient response and thus is more favorable than voltage-mode control. There are only a few publicationsonhowtodesignandimplementafullyintegrateddig- ital controller as the on-chip implementation is very challenging, especiallyforcurrent-modecontrol.Thispaperaddressesthosede- sign challenges and considerations. One of the main challenges is to efficiently sample and quantize both the output voltage and in-

  3. Single inductor quad-input-dual-output buck converter for photovoltaic systems

    Microsoft Academic Search

    K. W. R. Chew; L. Siek

    2010-01-01

    Stand-alone photovoltaic (SAPV) system is more favourable than grid connected photovoltaic (PV) system in areas where extension of power grid is impracticable. However, the high set up cost of a SAPV system requires cost efficient solar energy harvesting methods. To improve the energy harvesting efficiency of a PV system, a large, centrally controlled PV array can be rearranged into smaller

  4. A new pulsed power supply topology based on positive buck-boost converters concept

    Microsoft Academic Search

    Sasan Zabihi; Firuz Zare; Gerard Ledwich; Arindam Ghosh; Hidenori Akiyama

    2010-01-01

    Improving efficiency and flexibility in pulsed power supply technologies is the most substantial concern of pulsed power systems specifically with regard to plasma generation. Recently, the improvement of pulsed power supply has become of greater concern due to the extension of pulsed power applications to environmental and industrial areas. With this respect, a current source based topology is proposed in

  5. 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.

  6. 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.

  7. 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…

  8. 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.

  9. 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,

  10. Series Connected Converter for Control of Multi-Bus Spacecraft Power Utility

    NASA Technical Reports Server (NTRS)

    Beach, Raymond F. (Inventor); Brush, Andy (Inventor)

    1997-01-01

    The invention provides a power system using series connected regulators. Power from a source, such as a solar array, is processed through the regulators and provided to corresponding buses used to charge a battery and supply loads. The regulators employ a bypass loop around a DC-DC converter. The bypass loop connects a hot input of the converter to a return output, preferably though an inductor. Part of the current from the source passes through the bypass loop to the power bus. The converter bucks or boosts the voltage from the source to maintain the desired voltage at the bus. Thus, only part of the power is processed through the converter. The converter can also be used without the bypass loop to provide isolation. All of the converters can be substantially identical.

  11. IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS, VOL. 19, NO. 6, JUNE 2011 1075 A Distributed Filter Within a Switching Converter for

    E-print Network

    Friedman, Eby G.

    arise. One primary requirement of 3-D integrated systems is diverse, high quality, and reliable power [2 voltage [5]. The filter portion of a buck converter to generate and distribute power supplies in 3-DIEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEMS, VOL. 19, NO. 6, JUNE 2011 1075

  12. A Novel Soft-Commutating Isolated Boost Full-Bridge ZVS-PWM DC–DC Converter for Bidirectional High Power Applications

    Microsoft Academic Search

    Lizhi Zhu

    2006-01-01

    A soft-commutating method and control scheme for an isolated boost full bridge converter is proposed in this paper to implement dual operation of the well-known soft-switching full bridge dc\\/dc buck converter for bidirectional high power applications. It provides a unique commutation logic to minimize a mismatch between current in the current-fed inductor and current in the leakage inductance of the

  13. Improved digital peak current control of switching dc-dc converters with single-edge and dual-edge pulse-width modulations

    Microsoft Academic Search

    Guohua Zhou; Jianping Xu; Ming Qin; Yanyan Jin

    2009-01-01

    Improved digital peak current (IDPC) control technique of switching dc-dc converters with single-edge (trailing-edge and leading-edge) and dual-edge (leading-triangle and trailing-triangle) pulse-width modulations is studied in this paper. The control laws by using these four modulation methods are derived and compared with buck converter as an example. Their stabilities are analyzed and small-signal analysis is performed with comparison among these

  14. Three-Level AC–DC–AC Z-Source Converter Using Reduced Passive Component Count

    Microsoft Academic Search

    Poh Chiang Loh; Feng Gao; Pee-Chin Tan; Frede Blaabjerg

    2009-01-01

    This paper presents a three-level AC-DC-AC Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected

  15. Holmes' conclusions 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 false analogy In the Supreme Court decision, Justice Holmes compared sterilization for feeblemindedness to a vaccination for smallpox.

  16. 77 FR 12323 - Draft Environmental Impact Statement for the General Management Plan, Buck Island Reef National...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-29

    ...C) of the National Environmental Policy Act of 1969 and National Park Service (NPS...Order Number 2 (Park Planning) and...Order Number 12 (Conservation Planning, Environmental...Buck Island Reef National Monument,...

  17. 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.

  18. 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.

  19. 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.

  20. The Buck vs. Bell decision, 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 Sterilization is justified The case conluded that Carrie, Emma, and Vivian represented three generations of imbeciles, which justified Carrie's sterilization.

  1. 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.

  2. Holmes' statements 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 champion of human rights? Oliver Wendell Holmes' support for eugenic sterilization was contrary to his record as a defender of civil liberties.

  3. 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.

  4. More Dakota texts: collections of Alanson Buck Skinner and Amos Oneroad

    E-print Network

    Anderson, Laura Lee

    1993-01-01

    OF ARTS May 1993 Major Subject: Anthropology MORE DAKOTA TEXTS: COLLECTIONS OF ALANSON BUCK SKINNER AND AMOS ONEROAD A Thesis by LAURA LEE ANDERSON Approved as to style and content by: ylvia A Grider (Chair of Committee) Thomas A. Green, (Member...) Barbara Johnstone (Member) Vaughn M. B yant, r. (Head of Department) May 1993 ABSTRACT More Dakota Texts: Collections of Alanson Buck Skinner and Amos Oneroad. (May 1993) Laura Lee Anderson, B. A. , University of South Dakota Chair of Advisory...

  5. An integrated CMOS current-sensing circuit for low-Voltage current-mode buck regulator

    Microsoft Academic Search

    Chi Yat Leung; Philip K. T. Mok; Ka Nang Leung; Mansun Chan

    2005-01-01

    An integrated current-sensing circuit for low-voltage buck regulator is presented. The minimum achievable supply voltage of the proposed current-sensing circuit is 1.2 V implemented in a CMOS technology with VTH=0.85 V, and the current-sensing accuracy is higher than 94%. With the developed current-sensing circuit, a buck regulator, which is able to operate at a 1.2-V supply, is implemented. A maximum

  6. A voltage-mode PWM buck regulator with end-point prediction

    Microsoft Academic Search

    Man Siu; P. K. T. Mok; Ka Nang Leung; Y.-H. Lam; Wing-Hung Ki

    2006-01-01

    The end-point prediction (EPP) scheme for voltage-mode buck regulators is proposed. Internal nodal voltages of the regulator controller are predicted and set automatically by the proposed algorithms and circuits. The settling time of the regulator can therefore be significantly reduced for faster dynamic responses, even with dominant-pole compensation. Proven experimentally by a voltage-mode buck regulator implemented in a 0.35-?m CMOS

  7. Current Source Converters in Discontinuous Conduction Modes of Operation

    NASA Astrophysics Data System (ADS)

    Cuzner, Robert M.

    This work demonstrates that Current Source Rectifier (CSR) pulse-width modulation (PWM) can be successfully modified for discontinuous conduction mode (DCM). DCM is characterized by input current distortion and non-linear input to output voltage ratio. A Dead-Beat Current Injection (DBCI) PWM method is developed that ensures sinusoidal input currents and linear input to output voltage control while in DCM. A method for control analysis is proposed that enables design of the CSR closed loop voltage controller. The proposed method is simulated to show that the desired objectives are achieved at no load and very light load, where the CSR operates in an extreme DCM condition. Experimental results verify performance of the DBCI-PWM method and validate both simulation and analytical tools used to explore the capabilities of the approach. Index Terms---Active buck rectifier, Current source rectifier (CSR), current source PWM rectifier, power conversion, power converter design, power converter analysis, input power quality

  8. Abnormalities of the testes and epididymis in bucks and rams slaughtered at Debre Zeit abattoir, Ethiopia.

    PubMed

    Regassa, F; Terefe, F; Bekana, M

    2003-12-01

    A study was conducted at Debre Zeit export abattoir on 404 bucks belonging to four breeds and 167 rams of two breeds. The animals were selected from the slaughter flock using stratified sampling based on breed. Ante-mortem and post-mortem examinations were carried out after each animal was carefully identified. Various genital abnormalities were observed, among which testicular atrophy and epididymitis were the predominant genital problems in both bucks and rams. The prevalence of cryptorchidism was higher (p<0.05) in bucks than in rams, while epididymitis (p<0.05), sperm granuloma (p<0.01) and epididymal cysts (p<0.05) were more frequent in rams. In bucks, none of these abnormalities was significantly associated with age (p>0.05). However, testicular atrophy (p<0.01), epididymitis (p<0.01) and haemorrhagic lesions (p<0.05) were associated with breed, the prevalence being higher in Woito-Guji and Boran bucks than in the Arsi-Bale and Afar breeds. In rams, age affected (p<0.05) the incidence of testicular atrophy, epididymitis and sperm granulomas. Epididymitis, sperm granuloma and epididymal cysts were more frequent (p<0.01) in Adal rams than in Black Head Somalis. PMID:14690091

  9. Gertrude Buck's Approach to Argumentation: Preparing Women for a More Active and Vocal Role in a Democracy.

    ERIC Educational Resources Information Center

    Bordelon, Suzanne

    1998-01-01

    Explores Gertrude Buck's approach to argumentation demonstrating the intellectual and social significance of her work and showing how she introduced a democratic ethics encouraging Vassar women to take a more active and public role in society. Focuses on one of Buck's instruments of teaching writing, "A Course in Argumentative Writing" (1899), and…

  10. 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.

  11. Genetic and non-genetic parameters of several characteristics of production and semen quality in young bucks

    Microsoft Academic Search

    V. Furstoss; I. David; B. Leboeuf; P. Guillouet; P. Boué; L. Bodin

    2009-01-01

    The objective of this study was to evaluate genetic and non-genetic factors influencing characteristics of young buck semen production using a multivariate model that takes into account the longitudinal structure of data. Data were collected from 1989 to 2002 at two French A.I. centres. The data corresponded to 13151 and 9206 ejaculates of 758 Alpine and 535 Saanen bucks respectively,

  12. Full bridge converter Transformers and isolated converters

    E-print Network

    Knobloch,Jürgen

    control. 2. High power factor PFC - discussed previously. 3. Isolation 4. Multiple outputs IsolatedFull bridge converter Transformers and isolated converters Most DC power supplies have the following requirements: 1. Regulated output voltage Solved by a large capacitor at the output, and feedback

  13. Switching Power Converter A/D Converters

    E-print Network

    " monitoring capable of measuring system performance and detecting faults or anomalies in the operation using A/D converters and the data is sent to a digital controller for processing. A system interface then displays processed data concerning the converter health status. Online Health Monitoring in Digitally

  14. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The feasibility study has shown that a dump/fill type torque converter has excellent potential for the convertible fan/shaft engine. The torque converter space requirement permits internal housing within the normal flow path of a turbofan engine at acceptable engine weight. The unit permits operating the engine in the turboshaft mode by decoupling the fan. To convert to turbofan mode, the torque converter overdrive capability bring the fan speed up to the power turbine speed to permit engagement of a mechanical lockup device when the shaft speed are synchronized. The conversion to turbofan mode can be made without drop of power turbine speed in less than 10 sec. Total thrust delivered to the aircraft by the proprotor, fan, and engine during tansient can be controlled to prevent loss of air speed or altitude. Heat rejection to the oil is low, and additional oil cooling capacity is not required. The turbofan engine aerodynamic design is basically uncompromised by convertibility and allows proper fan design for quiet and efficient cruise operation. Although the results of the feasibility study are exceedingly encouraging, it must be noted that they are based on extrapolation of limited existing data on torque converters. A component test program with three trial torque converter designs and concurrent computer modeling for fluid flow, stress, and dynamics, updated with test results from each unit, is recommended.

  15. Variable output, soft-switching DC\\/DC converter for VLSI dynamic voltage scaling power supply applications

    Microsoft Academic Search

    Olivier Trescases; Wai Tung Ng

    2004-01-01

    The implementation of a low-voltage zero-voltage-switching quasi-square-wave (ZVS-QSW) buck converter capable of meeting the future challenges of low-voltage VRMs is presented. By eliminating switching losses, high-efficiency operation at switching frequencies beyond 1 MHz is achieved. The design uses novel high-speed dead-time-locked-loops with fast dead-time error rejection to ensure zero-voltage-switching under dynamic loads and variable output conditions. The ZVS-QSW converter, which

  16. Implementing a Farmers’ Market Incentive Program: Perspectives on the New York City Health Bucks Program

    PubMed Central

    Wethington, Holly; Olsho, Lauren; Jernigan, Jan; Farris, Rosanne; Walker, Deborah Klein

    2013-01-01

    Introduction One strategy for lowering the prevalence of obesity is to increase access to and affordability of fruits and vegetables through farmers’ markets. However, little has been documented in the literature on the implementation of such efforts. To address this gap, the Division of Nutrition, Physical Activity, and Obesity (DNPAO) sponsored an evaluation of the New York City Health Bucks program, a farmers’ market coupon incentive program intended to increase access to fresh fruits and vegetables in underserved neighborhoods while supporting local farmers. Methods We conducted a process evaluation of Health Bucks program implementation. We interviewed 6 farmer/vendors, 3 market managers, and 4 program administrators, and collected data on site at 86 farmers’ markets, including surveys of 81 managers and 141 farmer/vendors on their perspectives on promotion and redemption of the incentive coupons; knowledge and attitudes regarding the program; experiences with markets and products; and facilitators and barriers to program participation. Results Results indicate that respondents view Health Bucks as a positive program model. Farmers’ market incentive coupon programs like Health Bucks are one strategy to address the problem of obesity and were associated with higher fruit and vegetable access and purchases in low-income communities. Conclusions This evaluation identified some areas for improving implementation of the Health Bucks program. Farmers’ market incentive programs like Health Bucks may be one avenue to increase access to and affordability of fruits and vegetables among low-income persons. Further research is needed to assess the potential effects of these programs on access and health outcomes. PMID:23987251

  17. 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.

  18. Measurement: Converting Distances

    NSDL National Science Digital Library

    2006-01-01

    This lesson helps students understand and practice converting measurements in both English and metric systems. The 8-page pdf begins with a brief introduction to measuring length, English measurement systems, and metric measurement. Students then learn to convert measurements within each system. At the end of the lesson, there are 18 review problems for students to convert measurements on their own. Answers are provided.

  19. DC-DC converter current source fed naturally commutated brushless DC motor drive

    E-print Network

    Khopkar, Rahul Vijaykumar

    2004-11-15

    of buck fed CSI drive in Fig. 22 ................................................... 41 II Cost analysis of the Cuk converter supplied CSI BLDC drive in Fig. 31.......... 51 III Comparison of ferrite and iron-powder core inductors...-emf is trapezoidal as shown in Fig. 5. 0 60 120 180 240 300 360 60 120 180 aE bE cE t t t Fig. 5. Trapezoidal back-emf of a three-phase BLDC 6 The cheapest permanent magnets are usually made from ferrite (have low coercive strength), whereas the more expensive...

  20. 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.

  1. 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

  2. Do Wolves Affect White-Tailed Buck Harvest In Northeastern Minnesota?

    NSDL National Science Digital Library

    Mech, L. David.

    In early 2000 the Northern Prairie Wildlife Research Center posted this resource on wolves at their Website. "Do Wolves Affect White-Tailed Buck Harvest In Northeastern Minnesota?" summarizes wolf impacts on deer hunting in northeastern Minnesota from 1975 to 1977. The resource may be downloaded as a .zip file.

  3. 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

  4. LIBIDO TEST SCORES, BODY CONFORMATION AND TESTICULAR TRAITS IN BOER AND KIKO GOAT BUCKS

    Microsoft Academic Search

    D. Ford Jr.; C. Okere; O. Bolden-Tiller

    Independent of whether natural mating or artificial insemination is used for breeding, libido (sex drive) is evidently crucial to reproductive competence in all male meat animal species. Breeding goat bucks vary in their levels of libido; therefore, there is a need for the development of a predictive standardized test for estimating sex drive. The objective of this study was to

  5. Serum amino acid and myofibrillar protein profiles in Boer goat bucks following undernutrition

    Microsoft Academic Search

    A. M. Almeida; L. M. J. Schwalbach; H. O. deWaal; J. P. C. Greyling; L. A. Cardoso

    2004-01-01

    The aim of the work was to determine serum free amino acid and myofibrillar protein profiles in Boer goats following undernutrition in order to study the physiological consequences of undernutrition in this goat breed. Fifteen Boer goat bucks were allocated to two experimental groups: CG (control group), fed ad libitum Themeda trianda hay, supplemented with maize, molasses and urea; and

  6. Clifton Stryker Buck, Ph.D. University of California -Santa Cruz cbuck@ucsc.edu

    E-print Network

    Paytan, Adina

    terrestrial and marine environments using ion chromatography and inductively coupled plasma mass spectrometry and conducted analyses using ion chromatography, inductively coupled plasma mass spectrometry, and flame) Ranville, M., G. Cutter, C.S. Buck, W.M. Landing, L. Cutter, J. Resing, R.A., Flegal (2009). Aeolian

  7. More Bang for Their Bucks: Assessing New Features for Online Advertisers

    E-print Network

    Tomkins, Andrew

    More Bang for Their Bucks: Assessing New Features for Online Advertisers Diane Lambert Google, Inc features that advertisers can use to fine-tune and enhance their ad campaigns. An important question is whether a new feature actually helps advertisers. In an ideal world for statisticians, we would answer

  8. 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

  9. A Streaming Programming Environment Ian Buck, Mattan Erez, Ben Chelf, Pat Hanrahan

    E-print Network

    Dally, William J.

    Brook A Streaming Programming Environment Ian Buck, Mattan Erez, Ben Chelf, Pat Hanrahan Streaming Languages Compilation System Architecture Node Architecture StreamFlo StreamMD StreamFEM Kernel Streams ­ Contiguous 1D view of records in memory ­ Operated on in parallel ­ Declarations: · stream float floats

  10. Vegetation Dynamics of the Buck Creek Serpentine Barrens, Clay County, North Carolina Elizabeth Marx

    E-print Network

    Peet, Robert K.

    Vegetation Dynamics of the Buck Creek Serpentine Barrens, Clay County, North Carolina By Elizabeth of North Carolina-Chapel Hill Fall 2007 Dr. Robert K. Peet Research Advisor #12;2 Abstract Serpentine taxa. The open and well-drained conditions leave serpentine sites susceptible to more frequent fires

  11. PARASITISM OF BARRENS BUCK MOTH HEMILEUCA MAIA DRURY IN EARLY AND LATE SUCCESSIONAL PINE BARRENS HABITATS

    Microsoft Academic Search

    JENNIFER A. SELFRIDGE; DYLAN PARRY; GEORGE H. BOETTNER

    Barrens buck moth, Hemileuca maia, is predominantly associated with early successional pine barrens dominated by scrub oak, Quercus ilicifolia. To determine if H. maia's association with these open habitats within pine barrens on Cape Cod is due to reduced rates of parasitism, we compared mortality of H. maia larvae on scrub oak in early successional right-of-way habitat and climax pitch

  12. Evaluation of SiC MOSFETs for a High Efficiency Three-Phase Buck Rectifier

    E-print Network

    Tolbert, Leon M.

    Evaluation of SiC MOSFETs for a High Efficiency Three-Phase Buck Rectifier Fan Xu, Ben Guo, Leon M, 33 A SiC MOSFET and a 1200 V, 60 A SiC schottky barrier diode (SBD). The switching characteristics (SDBs) and Si MOSFETs is presented in [6]. The efficiency of it is 98.8%. This paper presents

  13. Effect of photoperiod on semen production and quality in bucks of Verata and Malagueña breeds

    Microsoft Academic Search

    B. Pérez; E. Mateos

    1996-01-01

    A group of 19 bucks of two Spanish breeds from different latitudes (Verata 40 °N, n = 10, and Malagueña 37 °N, n = 9) were used to study the effect of photoperiod on semen characteristics (volume, concentration, number of total sperm per ejaculation, motility percentage, percentage of normal acrosomes and percentage of abnormal forms). Semen samples were collected once

  14. Effect of photoperiod on semen production and quality in bucks of Verata and Malagueña breeds

    Microsoft Academic Search

    B. Pérez; E. Mateos

    1996-01-01

    A group of 19 bucks of two Spanish breeds from different latitudes (Verata, 40 °N, n = 10; Malagueña, 37 °N, n = 9) was used to study the effect of photoperiod on semen characteristics (volume, concentration, number of total sperm per ejaculation, motility percentage, percentage of normal acrosomes and percentage of abnormal forms). Semen samples were collected once a

  15. 1927 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 Carrie's sterilization in context. Carrie's one-hour sterilization took place in 1927, the same year that Babe Ruth hit 60 home runs and Charles Lindbergh flew solo across the Atlantic.

  16. 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.

  17. Boost Converters for Gas Electric and Fuel Cell Hybrid Electric Vehicles

    SciTech Connect

    McKeever, JW

    2005-06-16

    Hybrid electric vehicles (HEVs) are driven by at least two prime energy sources, such as an internal combustion engine (ICE) and propulsion battery. For a series HEV configuration, the ICE drives only a generator, which maintains the state-of-charge (SOC) of propulsion and accessory batteries and drives the electric traction motor. For a parallel HEV configuration, the ICE is mechanically connected to directly drive the wheels as well as the generator, which likewise maintains the SOC of propulsion and accessory batteries and drives the electric traction motor. Today the prime energy source is an ICE; tomorrow it will very likely be a fuel cell (FC). Use of the FC eliminates a direct drive capability accentuating the importance of the battery charge and discharge systems. In both systems, the electric traction motor may use the voltage directly from the batteries or from a boost converter that raises the voltage. If low battery voltage is used directly, some special control circuitry, such as dual mode inverter control (DMIC) which adds a small cost, is necessary to drive the electric motor above base speed. If high voltage is chosen for more efficient motor operation or for high speed operation, the propulsion battery voltage must be raised, which would require some type of two-quadrant bidirectional chopper with an additional cost. Two common direct current (dc)-to-dc converters are: (1) the transformer-based boost or buck converter, which inverts a dc voltage, feeds the resulting alternating current (ac) into a transformer to raise or lower the voltage, and rectifies it to complete the conversion; and (2) the inductor-based switch mode boost or buck converter [1]. The switch-mode boost and buck features are discussed in this report as they operate in a bi-directional chopper. A benefit of the transformer-based boost converter is that it isolates the high voltage from the low voltage. Usually the transformer is large, further increasing the cost. A useful feature of the switch mode boost converter is its simplicity. Its inductor must handle the entire current, which is responsible for its main cost. The new Z-source inverter technology [2,3] boosts voltage directly by actively using the zero state time to boost the voltage. In the traditional pulse width modulated (PWM) inverter, this time is used only to control the average voltage by disconnecting the supply voltage from the motor. The purpose of this study is to examine the Z-source's potential for reducing the cost and improving the reliability of HEVs.

  18. Energy management of hydrogen-based stand-alone renewable energy system by using boost and buck converters

    Microsoft Academic Search

    Kodjo Agbossou; Sousso Kélouwani; Adil Anouar; Mohanlal Kolhe

    2004-01-01

    Electrolytic hydrogen offers a promising alternative for long-term energy storage of renewable energy (RE). A stand-alone RE system based on energy storage in the form of hydrogen has been developed at the Hydrogen Research Institute and successfully tested for automatic operation with an in-house designed control system and power conditioning devices. In this system the excess energy with respect to

  19. Non-grid-connected wind power generating system with permanent magnet synchronous generator and buck\\/boost converter

    Microsoft Academic Search

    Lei Dong; Shuang Gao; Mi Liu; Xiaozhong Liao

    2009-01-01

    In this paper, a distributed generation wind energy conversion system based on non-grid-connected and using a direct-drive permanent magnet synchronous generator (DD-PMSG) is proposed with a dual-loop PI controller. This energy system is suitable for applications in remote areas not connected to the grid such as Radio Base Stations (RBS) for mobile phone communications. Analysis, simulation, and prototyping test results

  20. Dual Modulation Technique for High Efficiency in High-Switching Buck Converters Over a Wide Load Range

    Microsoft Academic Search

    Jen-Chieh Tsai; Tsung-Ying Huang; Wang-Wei Lai; Ke-Horng Chen

    2011-01-01

    A dual modulation technique to improve power con- version efficiency with minimal increase in output voltage ripple is presented. The worsening switching noise caused by parasitic re- sistance and inductance due to high-switching operation can also be alleviated by the proposed ac ripple detector. Furthermore, the dual modulation method can speed up the load transient response since the switching frequency

  1. Dual-mode current-fed semi-quadratic buck-boost converter for transformerless modular photovoltaic applications

    Microsoft Academic Search

    Lari Nousiainen; Teuvo Suntio

    2011-01-01

    The urge to utilize green energy supplies increases the number of grid-connected photovoltaic (PV) energy systems. Transformerless inverter technology is a key for efficient and low cost solutions. In order to achieve the high DC link voltage required by the transformerless single-stage inverter, numerous photovoltaic modules has to be connected in series. In a long string, the mismatch losses of

  2. A Bidirectional High-Power-Quality Grid Interface With a Novel Bidirectional Noninverted Buck–Boost Converter for PHEVs

    Microsoft Academic Search

    Omer C. Onar; Jonathan Kobayashi; Dylan C. Erb; Alireza Khaligh

    2012-01-01

    Plug-in hybrid electric vehicles (PHEVs) will play a vital role in future sustainable transportation systems due to their potential in terms of energy security, decreased environmental impact, improved fuel economy, and better performance. Moreover, new regulations have been established to improve the collective gas mileage, cut greenhouse gas emissions, and reduce dependence on foreign oil. This paper primarily focuses on

  3. 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.

  4. The first witness at 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>trial Arthur Estabrook's testimony Arthur Estabrook, a psychologist for the Eugenics Record office, testified that Carrie, her daughter Vivian, and her mother Emma were all feeblminded.

  5. 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

    Fifteen yearling fallow bucks were randomly assigned by body weight to one of three treatment groups: control (C; n=5), melengestrol acetate (MGA; n=5), and zeranol (Z; n=5), to evaluate effects on testicular development, aggressive behavior...

  6. 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.

  7. Carrie Buck's wedding photograph, still image with audio by Paul LombardoSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    DNAi location: Chronicle>Trial of Carrie Buck>epilogue Carrie Buck sent this photo, taken on her wedding day in 1933, to Dr. Bell, still at the Virginia Colony for Epileptics and Feebleminded. She remained married to Mr. Eagle, shown here in the wedding picture, for 25 years. Though it was claimed that she was unstable, morally uninhibited, and feebleminded, this first marriage lasted a quarter of a century until the death of her spouse.

  8. Wave-energy converter

    Microsoft Academic Search

    1985-01-01

    The invention provides a device for converting wave energy into useful work, and comprises a body adapted to be moved to and fro by waves on a liquid, and means such as a hydraulic piston in a cylinder for converting this movement of the body into a power output. The body may be disposed about a horizontal cable along which

  9. Wave-energy converter

    Microsoft Academic Search

    1982-01-01

    The invention provides a device for converting wave energy into useful work, and comprises a body adapted to be moved to and fro by waves on a liquid, and means such as a hydraulic piston in a cylinder for converting this movement of the body into a power output. The body may be disposed about a horizontal cable along which

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Polymorphism of the growth hormone gene and its association with growth traits in Boer goat bucks

    Microsoft Academic Search

    G. H. Hua; S. L. Chen; J. N. Yu; K. L. Cai; C. J. Wu; Q. L. Li; C. Y. Zhang; A. X. Liang; L. Han; L. Y. Geng; Z. Shen; D. Q. Xu; L. G. Yang

    2009-01-01

    In the present study, the polymorphism of growth hormone (GH) gene was analyzed as a genetic marker candidate for growth traits in Boer goat bucks. Two single nucleotide polymorphisms (SNPs) – A781G (Ser\\/Gly35) and A1575G (Leu147), were identified by GH gene sequencing and PCR–RFLP (polymerase chain reaction–restriction fragment length polymorphism) analysis. AA genotype resulted in a significant decrease in birth

  15. The effect of supplementation on productive performance of Boer goat bucks fed winter veld hay

    Microsoft Academic Search

    A. M. Almeida; L. M. Schwalbach; H. O. de Waal; J. P. C. Greyling; L. A. Cardoso

    2006-01-01

    Fifteen Boer goat bucks, (6–8 months old), were allocated into two groups and fed ad libitum for a period of 29 days. The WH group (winter hay; n = 8) received a chopped diet consisting of grass hay, predominantly Themeda\\u000a trianda grass (cut during the winter) from a natural pasture (veld). The WH+S group (winter hay plus supplement; n =

  16. Design of anti-jamming current-sensing circuit for current-mode buck regulator

    Microsoft Academic Search

    Yuan Bing; Lai Xinquan; Li Yanming; Ye Qiang; Jia Xinzhang

    2009-01-01

    A novel anti-jamming integrated CMOS current-sensing circuit for current-mode buck regulators is presented. Based on the widely-used traditional current-sensing structure, anti-jamming performance is improved significantly by adding on-chip capacitors and one-shot circuit. Also the transient response is faster through the introduction of current offset. The circuit is concise, simple to implement and suits for SoC applications with single power supply.

  17. dl-Aspartic acid administration improves semen quality in rabbit bucks

    Microsoft Academic Search

    G. Macchia; E. Topo; N. Mangano; E. D’Aniello; R. Boni

    2010-01-01

    Recently, d-aspartic acid (d-Asp) has been suggested as being involved in mechanisms regulating reproduction activity in animals and human. In this study we analyzed the effects of dl-Asp oral administration on sperm production in the rabbit. Bucks from 60, bred in a genetic centre and used for semen production, were divided in 2 subgroups of 6 individuals. The treated group

  18. PDF to HTML Converter

    NSDL National Science Digital Library

    2010-01-01

    If you're looking for a way to convert pdf files to html, this helpful application can do just that. Visitors just need to click the browse button here to locate the pdf that they wish to transfer. After doing this, they will supply their own email, and seconds later, they will have the converted file. This version is compatible with all operating systems.

  19. Performance of a Voltage Step-Up/Step-Down Transformerless DC/DC Converter: Analytical Model

    NASA Astrophysics Data System (ADS)

    Suskis, P.; Rankis, I.

    2012-01-01

    The authors present an analytical model for a voltage step-up/step-down DC/DC converter without transformers. The proposed topology is a combination of classic buck and boost converters in one single circuit but with differing operational principles. The converter is developed for a wind power autonomous supply system equipped with a hydrogen electrolytic tank and a fuel cell for energy stabilization. The main power source of the hydrogen-based autonomous supply system is energized by a synchronous generator operating on permanent magnets and equipped with a diode bridge. The input voltage of the converter in this case varies in the range 0-700 V, while its output DC voltage must be 540 V according to the demand of other parts of the system. To maintain the rated voltage, a special electrical load regulation is introduced. The calculations of the converter, the generator (equipped with a diode bridge) as element of the power system supply joint, and the load replaced by resistance are verified with PSIM software.

  20. Vector generator scan converter

    DOEpatents

    Moore, J.M.; Leighton, J.F.

    1988-02-05

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.

  1. Vector generator scan converter

    DOEpatents

    Moore, James M. (Livermore, CA); Leighton, James F. (Livermore, CA)

    1990-01-01

    High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.

  2. Metallurgical study of thermionic converters

    Microsoft Academic Search

    PETER ROUKLOVE

    1969-01-01

    This paper describes some of the observations made as a result of the test of 180 thermionic converters and of the postmortem metallographic examination of approximately 50 converters. The causes and effects of converter abnormal performance are related to the results of the metallographic examinations. The materials and fabrication methods utilized in converter construction are discussed together with areas of

  3. Dual switched mode power converter

    Microsoft Academic Search

    PALLAB MIDYA; FRED H. SCHLERETH

    1989-01-01

    A dual power converter is introduced which addresses the problem of output ripple and switching losses in a switched power converter. One stage of the power converter is a conventional PWM (pulse-width modulated) converter, and the other stage is a linear source. The linear source controls the voltage directly, and the output current of the linear stage is used to

  4. HEAT DIODE CONVERTER

    Microsoft Academic Search

    M. Gottlieb; R. J. Zollweg; L. S. Richardson; A. E. Fein; J. G. DeSteese

    1963-01-01

    Experimental and theoretical investigations were made on several aspects ; of the cesium plasma thermionic converter. Data were taken on the electron ; emission properties of tungsten, tantalum, molybdenum, niobium, rhenium, iridium, ; and tantalum carbide. Two methods were used in this study; one was the ; measurement of the I-V characteristics of diodes using eminers of these materials ;

  5. 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.

  6. Liquid metal thermal electric converter

    DOEpatents

    Abbin, Joseph P. (Albuquerque, NM); Andraka, Charles E. (Albuquerque, NM); Lukens, Laurance L. (Albuquerque, NM); Moreno, James B. (Albuquerque, NM)

    1989-01-01

    A liquid metal thermal electric converter which converts heat energy to electrical energy. The design of the liquid metal thermal electric converter incorporates a unique configuration which directs the metal fluid pressure to the outside of the tube which results in the structural loads in the tube to be compressive. A liquid metal thermal electric converter refluxing boiler with series connection of tubes and a multiple cell liquid metal thermal electric converter are also provided.

  7. Bucking Coil Implementation on PMT for Active Cancelling of Magnetic Field

    SciTech Connect

    Gogami, T; Asaturyan, A; Bono, J; Baturin, P; Chen, C; Chiba, A; Chiga, N; Fujii, Y; Hashimoto, O; Kawama, D; Maruta, T; Maxwell, V; Mkrtchyan, A; Nagao, S; Nakamura, S N; Reinhold, J; Shichijo, A; Tang, L; Taniya, N; Wood, S A; Ye, Z

    2013-11-01

    Aerogel and water Cerenkov detectors were employed to tag kaons for a lambda hypernuclear spectroscopic experiment which used the (e,e'K{sup +}) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ~5 Gauss at the photomultiplier tubes (PMT) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.

  8. Bucking coil implementation on PMT for active canceling of magnetic field

    NASA Astrophysics Data System (ADS)

    Gogami, T.; Asaturyan, A.; Bono, J.; Baturin, P.; Chen, C.; Chiba, A.; Chiga, N.; Fujii, Y.; Hashimoto, O.; Kawama, D.; Maruta, T.; Maxwell, V.; Mkrtchyan, A.; Nagao, S.; Nakamura, S. N.; Reinhold, J.; Shichijo, A.; Tang, L.; Taniya, N.; Wood, S. A.; Ye, Z.

    2013-11-01

    Aerogel and water ?herenkov detectors were employed to tag kaons for a ? hypernuclear spectroscopic experiment which used the (e,e?K+) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ~5 gauss at the photomultiplier tubes for these detectors. These fields, which could not be easily passively shielded, would result in a lowered kaon detection efficiency if not mitigated. A bucking coil was placed on each photomultiplier tube to actively cancel this magnetic field, thus recovering kaon detection efficiency.

  9. 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.

  10. 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.

  11. Purplemath: Cancelling / Converting Units

    NSDL National Science Digital Library

    2009-08-14

    This page contains a step-by-step tutorial in converting between units. It begins with one-step conversions, progressing to problems requiring multiple unit conversion. Areas of frequent student difficulty are given extra attention by the author, who presents the tutorial in an informal writing style designed to engage high school students. This tutorial is part of an award-winning collection of free resources developed to promote understanding and confidence in algebra.

  12. Advanced thermionic converter development

    Microsoft Academic Search

    F. N. Huffman; D. Lieb; T. R. Briere; A. H. Sommer; F. Rufeh

    1976-01-01

    Recent progress at Thermo Electron in developing advanced thermionic converters is summarized with particular attention paid to the development of electrodes, diodes, and triodes. It is found that one class of materials (ZnO, BaO and SrO) provides interesting cesiated work functions (1.3-1.4 eV) without additional oxygen. The second class of materials studied (rare earth oxides and hexaborides) gives cesiated\\/oxygenated work

  13. Free FLV Converter

    NSDL National Science Digital Library

    2007-01-01

    Taking Flash files from the web can be a bit cumbersome, so this application will definitely be a most welcome find. This free Flash converter (the second to last link on the left) allows users to take Flash files and transfer them to formats appropriate for portable devices and other items. The site is available in both French and English and this particular version is compatible with computers running Windows 2000, XP, 2003, and Vista.

  14. Thermionic energy converters

    SciTech Connect

    Morris, J.F.

    1983-02-08

    This invention is concerned with improving the efficiency of thermionic energy converters. The invention is particularly directed to the reduction of plasma losses in these converters. This beneficial technical effect is achieved by internal distribution of tiny shorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. Specifically, the tiny, shorted 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 diode effect will increase with the use of metals that adsorb cesium less readily for the main emitter ends of the tiny protrusions and metals that adsorb cesium more readily for the main collector ends of the protrusions. By way of example, the main emitter can be made of rhenium or irridium; the main emitter ends of the protrusions can be made of tantalum or niobium; and the main collector ends of the protrusions can be made of platinum or irridium. 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.

  15. High-frequency high-voltage high-power DC-to-DC converters

    NASA Technical Reports Server (NTRS)

    Wilson, T. G.; Owen, H. A., Jr.; Wilson, P. M.

    1981-01-01

    The current and voltage waveshapes associated with the power transitor and the power diode in an example current-or-voltage step-up (buck-boost) converter were analyzed to highlight the problems and possible tradeoffs involved in the design of high voltage high power converters operating at switching frequencies in the range of 100 Khz. Although the fast switching speeds of currently available power diodes and transistors permit converter operation at high switching frequencies, the resulting time rates of changes of current coupled with parasitic inductances in series with the semiconductor switches, produce large repetitive voltage transients across the semiconductor switches, potentially far in excess of the device voltage ratings. The need is established for semiconductor switch protection circuitry to control the peak voltages appearing across the semiconductor switches, as well as to provide the waveshaping action require for a given semiconductor device. The possible tradeoffs, as well as the factors affecting the tradeoffs that must be considered in order to maximize the efficiency of the converters are enumerated.

  16. Driving circuit with high accuracy and large driving capability for high voltage buck regulators

    NASA Astrophysics Data System (ADS)

    Yajun, Li; Xinquan, Lai; Qiang, Ye; Bing, Yuan

    2014-12-01

    This paper presents a novel driving circuit for the high-side switch of high voltage buck regulators. A 40 V P-channel lateral double-diffused metal—oxide—semiconductor device whose drain—source and drain—gate can resist high voltage, but whose source—gate must be less than 5 V, is used as the high-side switch. The proposed driving circuit provides a stable and accurate 5 V driving voltage for protecting the high-side switch from breakdown and achieving low on-resistance and simple loop stability design. Furthermore, the driving circuit with excellent driving capability decreases the switching loss and dead time is also developed to reduce the shoot-through current loss. Therefore, power efficiency is greatly improved. An asynchronous buck regulator with the proposed technique has been successfully fabricated by a 0.35 ?m CDMOS technology. From the results, compared with the accuracy of 16.38% of the driving voltage in conventional design, a high accuracy of 1.38% is achieved in this work. Moreover, power efficiency is up to 95% at 12 V input and 5 V output.

  17. 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…

  18. Design of high output current, high switching frequency current mode buck DC-DC regulator in WLCSP for portable applications

    Microsoft Academic Search

    Bin Shao; Bill Liu

    2010-01-01

    The paper introduces a high output current and high switching frequency buck DC-DC regulator with gate scaling function to improve the efficiency at light load together with reduced output voltage ripple and noise. External FET driver is also implemented as an option to move the excessive heat from inside the chip for thermal sensitive applications. A fast current sensing loop

  19. 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

  20. 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

  1. 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.

  2. The microminiature thermionic converter

    NASA Astrophysics Data System (ADS)

    King, Donald Bryan

    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 fabrication of the MTC uses micromachining and semiconductor integrated circuit fabrication methods. These fabrication techniques allow the MTC to have an inter-electrode spacing of 20 microns or less with electrode materials having work functions ranging from 0.75 to 3 eV. The small gap size and low work function features of the MTC give it the potential to produce electricity at relatively high conversion efficiencies (20--25%). MTC designs may be tailored to function for different heat sources (combustion, solar, advanced nuclear reactors, radioisotopes, waste heat) over broad temperature regimes. The MTC diode prototype has been successfully fabricated, operated, and analyzed over a wide range of emitter and collector temperatures in the power production mode as well as power consumption mode. The emitter temperatures of interest ranged from 770 through 1220K. Maximum power output densities of 2mW/cm2 have been produced, and maximum output voltages approaching 1 Volt have also been produced. The MTC has been used to power an external load consisting of a Motorola 1N4004 diode. Models have been developed to characterize thermionic surface emission and electron transport across the gap. The MTC diode current-voltage characteristics and features have been successfully modeled over all five operational modes that characterize a thermionic converter. Power production has not been as high as expected. The shortcomings are due to the low work function material, (Ba,Sr,Ca)O, used in the diode. The tests and models indicate that the irregularities in work function across the emission material are detrimental to power production that occurs at low voltage in all thermionic converters. Modest improvements in surface homogeneity could increase the power output density by at least three orders of magnitude.

  3. 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.

  4. Universal Currency Converter

    NSDL National Science Digital Library

    The Universal Currency Converter site was developed by Xenon Laboratories. It provides currency conversion for most of the currencies in the world. The conversion rates for the currency are provided by The Bank of Montreal's Treasury Group. Visitors can also obtain a currency table for a selected base currency. The site also provides prices for silver, gold and platinum in the various currencies. Visitors can sign-up for the Currency Update Service which provides free currency table updates specified in the user-selected base currency once every business day.

  5. Improving Fruit and Vegetable Consumption Among Low-Income Customers at Farmers Markets: Philly Food Bucks, Philadelphia, Pennsylvania, 2011

    PubMed Central

    Aquilante, Jennifer L.; Solomon, Sara; Colby, Lisa; Kawinzi, Mukethe A.; Uy, Nicky; Mallya, Giridhar

    2013-01-01

    Introduction We evaluated whether Philly Food Bucks, a bonus incentive program at farmers markets, is associated with increased fruit and vegetable consumption and Supplemental Nutrition Assistance Program (SNAP) sales at farmers markets in low-income areas. Methods A convenience sample of 662 customers at 22 farmers markets in low-income neighborhoods in Philadelphia, Pennsylvania, was surveyed via face-to-face interviews. Questions addressed shopping characteristics, self-reported change in fruit and vegetable consumption, whether customers tried new fruits or vegetables, use of Philly Food Bucks, and demographic information. Market-level SNAP sales and Philly Food Bucks redemption data were also collected to monitor sales patterns. Results Philly Food Bucks users were significantly more likely than nonusers to report increasing fruit and vegetable consumption (OR, 2.4; 95% CI, 1.6–3.7; P < .001) and to report trying new fruits or vegetables (OR 1.8; 95% CI, 1.2–2.7; P = .006). At the market level, average SNAP sales more than doubled at farmers markets in low-income areas in the first 2 years of the Philly Food Bucks program. At the city’s largest farmers market in a low-income area, the program was associated with an almost 5-fold higher increase in annual SNAP sales compared with baseline. Conclusion Results from this study demonstrate that a bonus incentive program tied to SNAP was associated with self-reported increases in fruit and vegetable consumption and increased SNAP sales at participating farmers markets in low-income communities. More research is warranted to evaluate the long-term impact of bonus incentives on farmers market use, dietary behaviors, and health outcomes. PMID:24135390

  6. 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.

  7. 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.

  8. Unity power factor converter

    NASA Technical Reports Server (NTRS)

    Wester, Gene W. (Inventor)

    1980-01-01

    A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

  9. Converting Biomass to Products

    SciTech Connect

    Graybeal, Judith W.

    2006-06-01

    For nearly 30 years, PNNL has been developing and applying novel thermal, chemical and biological processes to convert biomass to industrial and consumer products, fuels and energy. Honors for technologies resulting from this research include the Presidential Green Chemistry Award and several Federal Laboratory Consortium and R&D 100 Awards. PNNL’s research and development activities address the complete processing scheme, from feedstock pretreatment to purified product recovery. The laboratory applies fundamental science and advanced engineering capabilities to biomass conversion and processing to ensure effective recovery of optimal value from biomass; carbohydrate polymer systems to maximize energy efficiencies; and micro-technology systems for separation and conversion processes. For example, bioproducts researchers in the laboratory’s Institute for Interfacial Catalysis develop and demonstrate the utility of new catalyst formulations for production of bio-based chemicals. This article describes a sampling of current and recent catalysis projects for biomass conversion.

  10. Solution of the Schrödinger equation containing a Perey-Buck nonlocality

    E-print Network

    George H. Rawitscher

    2012-05-09

    The solution of a radial Schr\\"odinger equation for {\\psi}(r) containing a nonlocal potential of the form \\int{K(r,r') {\\psi}(r') dr'} is obtained to high accuracy by means of two methods. An application to the Perey-Buck nonlocality is presented, without using a local equivalent representation. The first method consists in expanding {\\psi} in a set of Chebyshev polynomials, and solving the matrix equation for the expansion coefficients numerically. An accuracy of between 1:10^{6} to 1:10^{14} is obtained, depending on the number of polynomials employed. The second method consists in expanding {\\psi} into a set of N Sturmian functions of positive energy, supplemented by an iteration procedure. For N=15 an accuracy of 1:10^{4} is obtained without iterations. After one iteration the accuracy is increased to 1:10^{6}. The method is applicable to a general nonlocality K.

  11. An integrated bi-directional power electronic converter with multi-level AC-DC\\/DC-AC converter and non-inverted buck-boost converter for PHEVs with minimal grid level disruptions

    Microsoft Academic Search

    Dylan C. Erb; Omer C. Onar; A. Khaligh

    2010-01-01

    In order to increase energy independency and decrease harmful vehicle emissions, plug-in hybrid electric vehicles (PHEVs) have been suggested as viable replacements for conventional internal combustion (IC) vehicles. In the event that PHEVs do command a large market share, their interactions with the grid could either become a large asset or a large burden for the grid, depending on the

  12. A digitally controlled PWM/PSM dual-mode DC/DC converter

    NASA Astrophysics Data System (ADS)

    Shaowei, Zhen; Bo, Zhang; Ping, Luo; Sijian, Hou; Jingxin, Ye; Xiao, Ma

    2011-11-01

    A digitally controlled pulse width modulation/pulse skip modulation (PWM/PSM) dual-mode buck DC/DC converter is proposed. Its operation mode can be automatically chosen as continuous conduction mode (CCM) or discontinuous conduction mode (DCM). The converter works in PSM at DCM and in 2 MHz PWM at CCM. Switching loss is reduced at a light load by skipping cycles. Thus high conversion efficiency is realized in a wide load current. The implementations of PWM control blocks, such as the ADC, the digital pulse width modulator (DPWM) and the loop compensator, and PSM control blocks are described in detail. The parameters of the loop compensator can be programmed for different external component values and switching frequencies, which is much more flexible than its analog rivals. The chip is manufactured in 0.13 ?m CMOS technology and the chip area is 1.21 mm2. Experimental results show that the conversion efficiency is high, being 90% at 200 mA and 67% at 20 mA. Meanwhile, the measured load step response shows that the proposed dual-mode converter has good stability.

  13. Self-powered microthermionic converter

    DOEpatents

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  14. Effect of nutritional supplementation of Khat ( Catha edulis) on testicular growth and sperm production in Ethiopian bucks

    Microsoft Academic Search

    Yoseph Mekasha; Azage Tegegne; Heriberto Rodriguez-Martinez

    A study was conducted to characterize body and testicular growth and sperm production parameters in indigenous Ogaden goats fed a basal diet of hay and supplemented with either Khat leftovers or a concentrate. Forty bucks with a mean (±S.D.) initial body weight (BW) of 15.5±1.5kg were selected and randomly assigned to one of four dietary treatments for a period of

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. Converting Petroleum Coke to Electricity

    E-print Network

    Pavone, A.

    . This paper presents the operating history of US based plants converting petroleum coke to electricity, and presents generic economics for the conversion process utilizing three primary technologies available: conventional pulverized coke combustion...

  20. 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.

  1. Ecology of juvenile hawksbills (Eretmochelys imbricata) at Buck Island Reef National Monument, US Virgin Islands

    USGS Publications Warehouse

    Hart, Kristen M.; Sartain, Autumn R.; Hillis-Starr, Zandy-Marie; Phillips, Brendalee; Mayor, Philippe A.; Roberson, Kimberly; Pemberton, Roy A., Jr.; Allen, Jason B.; Lundgren, Ian; Musick, Susanna

    2013-01-01

    Surveys of juvenile hawksbills around Buck Island Reef National Monument, US Virgin Islands from 1994 to 1999 revealed distributional patterns and resulted in a total of 75 individual hawksbill captures from all years; turtles ranged from 23.2 to 77.7 cm curved carapace length (CCL; mean 42.1 ± 12.3 cm SD). Juveniles concentrated where Zoanthid cover was highest. Length of time between recaptures, or presumed minimum site residency, ranged from 59 to 1,396 days (mean 620.8 ± 402.4 days SD). Growth rates for 23 juveniles ranged from 0.0 to 9.5 cm year?1 (mean 4.1 ± 2.4 cm year?1SD). Annual mean growth rates were non-monotonic, with the largest mean growth rate occurring in the 30–39 cm CCL size class. Gastric lavages indicated that Zoanthids were the primary food source for hawksbills. These results contribute to our understanding of juvenile hawksbill ecology and serve as a baseline for future studies or inventories of hawksbills in the Caribbean.

  2. An Improved Power Quality BIBRED Converter-Based VSI-Fed BLDC Motor Drive

    NASA Astrophysics Data System (ADS)

    Singh, Bhim; Bist, Vashist

    2014-01-01

    This paper presents an IHQRR (integrated high-quality rectifier regulator) BIBRED (boost integrated buck rectifier energy storage DC-DC) converter-based VSI (voltage source inverter)-fed BLDC (brushless DC) motor drive. The speed control of BLDC motor is achieved by controlling the DC link voltage of the VSI using a single voltage sensor. This allows VSI to operate in fundamental frequency switching mode for electronic commutation of BLDC motor which reduces the switching losses due to high-frequency switching used in conventional approach of PWM (pulse width modulation)-based VSI-fed BLDC motor drive. A BIBRED converter is operated in a dual-DCM (discontinuous conduction mode) thus using a voltage follower approach for PFC (power factor correction) and DC link voltage control. The performance of the proposed drive is evaluated for improved power quality over a wide range of speed control and supply voltage variation for demonstrating the behavior of proposed drive. The power quality indices thus obtained are within the recommended limits by international PQ (power quality) standards such as IEC 61000-3-2.

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

    NASA Astrophysics Data System (ADS)

    Divan, Deepakraj M.

    1990-12-01

    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.

  4. 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.

  5. Binary/BCD-to-ASCII data converter

    NASA Technical Reports Server (NTRS)

    Miller, A. J.

    1977-01-01

    Converter inputs multiple precision binary words, converts data to multiple precision binary-coded decimal, and routes data back to computer. Converter base can be readily changed without need for new gate structure for each base changeover.

  6. 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

  7. Effect of Supplementation with Agro-industrial By-products and Khat (Catha edulis) leftovers on testicular growth and sperm production in Ogaden bucks.

    PubMed

    Mekasha, Y; Tegegne, A; Rodriguez-Martinez, H

    2007-04-01

    The aim of this study was to characterize growth and sperm production parameters in Ogaden bucks fed a basal diet of hay and supplemented with agro-industrial by-products and Khat leftovers in Ethiopia. Thirty-five bucks with a mean (+/-SD) initial live body weight (BW) of 15.5 +/- 1.5 kg were randomly assigned to one of four dietary treatments for a period of 13 weeks. Treatments consisted of native hay fed ad libitum (control; C), native hay supplemented with a 1% of BW agro-industrial by-products (treatment 1; T1), native hay supplemented with Khat (Catha edulis) leftovers at a rate of 1% of BW (treatment 2; T2) and Khat leftovers fed ad libitum (treatment 3; T3). Bucks fed on T1-T3 had higher BW, body condition score, scrotal circumference (SC), testicular width and testicular length, compared to controls (P < 0.05). Also, bucks in T1-T3 had higher sperm progressive motility, sperm concentration per ml and total number of spermatozoa per ejaculate compared to controls (P < 0.05). Between treatments, bucks in T3 recorded the highest BW (17.2 +/- 0.16) and testicular size (21.1 +/- 0.17 cm). Both testicular and epididymal weight and dimensions were significantly affected (P < 0.05) by supplementation compared to controls. Testicular size was positively correlated to live BW (r = 0.53, P < 0.001). SC was positively correlated with ejaculate volume (r = 0.37, P < 0.001), sperm mass activity (r = 0.65, P < 0.001) and individual sperm progressive motility (r = 0.40; P < 0.001). Supplementation with Khat leftovers induced the highest improvement in live BW, testicular size, semen production and sperm motility in Ogaden bucks and can possibly be considered as a feed supplement to enhance goat production under smallholder livestock farming system in Ethiopia. PMID:17381680

  8. The Geography of European Convertible Bonds: Why Firms Issue Convertibles?

    E-print Network

    Saskatchewan, University of

    the global convertible market, suggesting that country-specific factors may play an important role in the use share of about 40% of the global market whereas most other countries have experienced dramatic changes to about 25% of the global market by the end of 2005. Why CBs find a more conducive growth environment

  9. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Sommer, A. H.; Balestra, C. L.; Briere, T. R.; Lieb, D.; Oettinger, P. E.; Goodale, D. B.

    1977-01-01

    Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

  10. A thermionic converter success story

    SciTech Connect

    Donovan, B.D.; Lamp, T.R. (Aerospace Power Division, Wright Laboratory Wright-Patterson AFB, OH 45433-6563 (United States)); Ramaligam, M.L. (UES, Inc. 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States))

    1993-01-20

    This paper summarizes the advanced out-of-core thermionic technology program being managed at Wright Laboratory: The Thermionic Critical Technology (TCT) Investigation. This program has been supported primarily by the United State Air Force for design and fabrication, and supported by Strategic Defense Initiative Organization (SDIO) for performance and life testing efforts. Converter design parameters, specifications, and performance testing data is summarized. Converters fabricated by Loral Electro Optical Systems (Loral EOS) under this program have exceeding performance requirements, and have demonstrated efficiencies as high as 14%.

  11. Microprocessor control of multiple peak power tracking DC/DC converters for use with solar cell arrays

    NASA Technical Reports Server (NTRS)

    Frederick, Martin E. (inventor); Jermakian, Joel (inventor)

    1991-01-01

    A method and an apparatus is provided for efficiently controlling the power output of a solar cell array string or a plurality of solar cell array strings to achieve a maximum amount of output power from the strings under varying conditions of use. Maximum power output from a solar array string is achieved through control of a pulse width modulated DC/DC buck converter which transfers power from a solar array to a load or battery bus. The input voltage from the solar array to the converter is controlled by a pulse width modulation duty cycle, which in turn is controlled by a differential signal controller. By periodically adjusting the control voltage up or down by a small amount and comparing the power on the load or bus with that generated at different voltage values a maximum power output voltage may be obtained. The system is totally modular and additional solar array strings may be added to the system simply by adding converter boards to the system and changing some constants in the controller's control routines.

  12. Current sharing in multiphase ZVT boost converter

    Microsoft Academic Search

    Esther de Jódar; José A. Villarejo; Jacinto Jiménez; Miguel Moreno

    2010-01-01

    Paralleling converters is a good choice for designing high frequency and high power converters. Nevertheless there must be a mechanism to share the load among phases to achieve all the benefits of parallel operation. A simple method to achieve current sharing is paralleling converters with high impedance. The ZVT Boost converter has interesting properties: Zero Voltage Transition, less semiconductors stress

  13. Damping assembly for a torque converter clutch

    Microsoft Academic Search

    Dull

    1989-01-01

    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

  14. 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.

  15. Hybrid-mode thermionic converter

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.; Britt, E. J.

    1976-01-01

    Converter's collector electrode has uniform low work-function surface and operates at sufficiently low temperature to produce negligible electron emission. Emitter electrode has main region which has intermediate work-function and auxiliary region which has relatively high work-function surface.

  16. Converting Work into College Credits

    ERIC Educational Resources Information Center

    Hoffman, Joseph A.

    1976-01-01

    The Cooperative Education Program conducted by the New Jersey Department of Labor and Industry and Thomas A. Edison College enables State labor department employees to work toward college degrees by attending free classes, taking college-level examinations for college credit, and converting work and life experiences into college credits.…

  17. Direct Drive Wave Energy Converters

    Microsoft Academic Search

    N. J. Baker; M. A. Mueller

    2001-01-01

    Over the last 25 years there have been numerous proposals for the conversion of energy contained within sea waves into electricity. Despite this fact, there is not yet one definitive wave energy device that stands out from the rest and developments in several concepts still continues. One aspect of a wave energy converter is the manner in which the physical

  18. 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.

  19. 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.

  20. Seasonal variation of plasminogen activator activity in spermatozoa and seminal plasma of boar, buck, bull and stallion.

    PubMed

    Zervos, I A; Lavrentiadou, S N; Tsantarliotou, M P; Georgiadis, M P; Kokolis, N A; Taitzoglou, I A

    2010-12-01

    Plasminogen activators (PA) are proteolytic enzymes present in the spermatozoa and seminal plasma of various species. They play a role in the binding of the spermatozoon and its penetration through the layers surrounding the oocyte. Plasminogen activator activity (PAA) is modulated by hormones that have a seasonal variation, such as testosterone and melatonin. The present study investigates the seasonal variation of PA activity in sperm extracts and seminal plasma of four farm animal species: boar, buck, bull and stallion. Semen samples were collected every second week during a 12-month period and PAA was determined. With respect to sperm enzyme activity, the boar showed a peak from late January until the beginning of April, whereas the activity in the bull was at the highest levels from April until October and gradually declined during autumn and winter period. Plasminogen activator activity of stallion spermatozoa peaked during March and April, and remained low throughout the rest of the year, whereas in the buck sperm, PAA increased from late October until the end of January. No biologically significant variation was detected regarding the seminal PAA activity in any of the species studied. While seasonality of reproduction is typically studied from the female perspective, the present data provide compelling information about a factor that may affect the reproductive ability of the male. PMID:20412514

  1. Micro-tomography and electron microscopy of a shock dike in the Buck Mountains 005 L6 chondrite

    NASA Astrophysics Data System (ADS)

    Brown, R.; Ruzicka, A. M.; Hutson, M.; Friedrich, J. M.; Rivers, M. L.

    2013-12-01

    Buck Mountains 005 is an L6 chondrite that contains a complexly structured shock dike. Scanning electron microscopy reveals that the dike consists of a holocrystalline, orthopyroxene-rich groundmass with a distinctive core-rim structure. Micro-tomography imaging shows that the dike is actually a sheet structure where the central sheet swells and pinches in a boudin-like fashion and is flanked by the rim. The central sheet entrains silicate clasts that were broken off and transported from the unmelted portion of the host. The flanking outer sheet is relatively clast free, but contains globules of metal with sulfides and bands of sheared, recrystallized Mg-olivine along the contact zone with the host. These two zones are separated by a thin band of sulfides with cellular metal that encloses euhedral silicate crystals. During dike formation, metal was mobilized and transported out of the dike and injected into the unmelted chondrite host, where it accumulated as larger grains. Formation of the dike can be attributed to localized shearing and heating that resulted in simple cataclasis and melting. The melt underwent FeO reduction and vaporization of volatile alkali elements, followed by rapid igneous crystallization. The combination of these processes transformed the mineralogy of the original chondrite, making it poorer in olivine and feldspar and richer in pyroxene. The Buck Mountain 005 dike presents further insight into the importance of shock in meteorites.

  2. Buck Creek Educational Corridor http://v4.wqdata.com/webdblink/buckcreek.php of this fact sheet is to intro-

    E-print Network

    Bogaerts, Steven

    Center on Witten- berg's campus, adjacent to Buck Creek. It provides wind speed, wind direc- tion, baro during runoff events Tributary of the Mad River which drains into the Great Miami and Ohio Rivers, and turbidity. Temperature - rates of biological and chemical pro- cesses depend on temperature. Temperature

  3. 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.

  4. 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)

    2011-03-15

    A rapidly deployable portable convertible blast effects shield/ballistic shield includes a set two or more frusto-conically-tapered telescoping 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 by the friction fit of adjacent pairs of frusto-conically-tapered rings to each other.

  5. 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.

  6. 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.

  7. Microenergy Converter Using Insect Wings

    Microsoft Academic Search

    Seiichi Sudo; Kazumasa Nashimoto; Koji Tsuyuki; Tetsuya Yano; Muneo Futamura

    This paper is concerned with the development of novel type of micro wind energy converter using insect wings. A series of\\u000a experimental studies are made on the function of wing apparatus of flying insects. In the first place, the structural properties\\u000a of insect wings are studied through measurements of certain morphological parameters. The scanning electron microscopic observation\\u000a of an insect

  8. Modular packaging of VSCF converters

    NASA Astrophysics Data System (ADS)

    Pollard, David D.

    1987-10-01

    The use of modular building blocks to configure VSCF converters of ratings varying from 40 to 110 kVA with an unvarying geometry for uniform circuit impedances is demonstrated. The various modules are described and means of implementating rating changes are considered. Alternate cooling methods such as air and oil are discussed and a description is given of the physical adjustments necessary for cooling compatibility. Weight, size, and efficiency data are provided for all ratings and cooling methods.

  9. 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.

  10. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed.

  11. Thermionic converter studies at Thermo Electron

    Microsoft Academic Search

    F. N. Huffman; D. Lieb; F. Rufeh

    1977-01-01

    The Thermionic Energy Converter (TEC) development program includes theoretical and experimental surface studies, diode evaluation, enhanced mode converter investigations and system studies, as well as materials fabrication and testing. The primary effort has been concentrated on increasing converter performance via improved electrodes. Diodes with oxide collectors (i.e., tungsten oxide, titanium oxide, zinc oxide and barium oxide) have provided the best

  12. Agilent 11982A Amplified Lightwave Converter

    E-print Network

    Park, Namkyoo

    Agilent 11982A Amplified Lightwave Converter Product Overview Wide bandwidth, sensitive O/E converter for characterizing lightwave systems and components Agilent's lightwave converter, the Agilent-end for lightwave frequency- and time- domain measurements. It can be used with Agilent spectrum analyzers

  13. 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

  14. 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

  15. 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.

  16. A single-inductor dual-output switching converter with average current mode control

    NASA Astrophysics Data System (ADS)

    Weiwei, Xu; Xiaoting, Zhu; Zhiliang, Hong; D, Killat

    2009-09-01

    An integrated single-inductor dual-output (SIDO) switching DC-DC converter is presented. The outputs are specified with 1.2 V/400 mA and 1.8 V/200 mA. A decoupling small signal model is proposed to analyze the multi-loop system and to design the on-chip compensators. An average current control mode is introduced with lossless, continuous current detection. The converter has been fabricated in a 0.25 ?m 2P4M CMOS process. The power efficiency is 86% at a total output power of 840 mW while the output ripples are about 40 mV at an oscillator frequency of 600 kHz.

  17. Fish population and habitat analysis in Buck Creek, Washington, prior to recolonization by anadromous salmonids after the removal of Condit Dam

    USGS Publications Warehouse

    Allen, M. Brady; Burkhardt, Jeanette; Munz, Carrie; Connolly, Patrick J.

    2012-01-01

    We assessed the physical and biotic conditions in the part of Buck Creek, Washington, potentially accessible to anadromous fishes. This creek is a major tributary to the White Salmon River upstream of Condit Dam, which was breached in October 2011. Habitat and fish populations were characterized in four stream reaches. Reach breaks were based on stream gradient, water withdrawals, and fish barriers. Buck Creek generally was confined, with a single straight channel and low sinuosity. Boulders and cobble were the dominant stream substrate, with limited gravel available for spawning. Large-cobble riffles were 83 percent of the available fish habitat. Pools, comprising 15 percent of the surface area, mostly were formed by bedrock with little instream cover and low complexity. Instream wood averaged 6—10 pieces per 100 meters, 80 percent of which was less than 50 centimeters in diameter. Water temperature in Buck Creek rarely exceeded 16 degrees Celsius and did so for only 1 day at river kilometer (rkm) 3 and 11 days at rkm 0.2 in late July and early August 2009. The maximum temperature recorded was 17.2 degrees Celsius at rkm 0.2 on August 2, 2009. Minimum summer discharge in Buck Creek was 3.3 cubic feet per second downstream of an irrigation diversion (rkm 3.1) and 7.7 cubic feet per second at its confluence with the White Salmon River. Rainbow trout (Oncorhynchus mykiss) was the dominant fish species in all reaches. The abundance of age-1 or older rainbow trout was similar between reaches. However, in 2009 and 2010, the greatest abundance of age-0 rainbow trout (8 fish per meter) was in the most downstream reach. These analyses in Buck Creek are important for understanding the factors that may limit fish abundance and productivity, and they will help identify and prioritize potential restoration actions. The data collected constitute baseline information of pre-dam removal conditions that will allow assessment of changes in fish populations now that Condit Dam has been removed and anadromous fish have an opportunity to recolonize Buck Creek.

  18. High power density dc\\/dc converter: Selection of converter topology

    Microsoft Academic Search

    Deepakraj M. Divan

    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

  19. Catalytic converter for an automobile

    SciTech Connect

    Retallick, W.B.

    1986-03-18

    A catalytic converter is described for an automobile comprising a single strip of metal folded back and forth upon itself, the strip having at least one slot along each line of folding, the slots being aligned with each other across adjacent layers of the strip, each folded slot defining a notch. The notches together define at least one groove along the periphery of the folded strip, and at least one canister section, the canister section being shaped to coincide with the shape of the folded strip, the canister section having at least one ridge shaped to mate with the groove, the canister section being wrapped around the folded strip so as to maintain the strip in a fixed position.

  20. 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.

  1. Modeling, control and implementation of the quasi-single stage three-phase zero-voltage zero-current switched buck rectifier

    Microsoft Academic Search

    C. Cuadros; S. Chandrasekaran; K. Wang; D. Boroyevich; F. C. Lee

    1999-01-01

    Large signal average model for the quasi-single stage three-phase zero-voltage zero-current switched (ZVZCS) buck rectifier operated with space vector modulation (SVM) is developed. The model reveals strong nonlinear relations between applied and effective duty-cycles, near the 60° electric sector boundaries, which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. PLL and look-up table based

  2. Grid-Tie Control of Cascade Dual-Buck Inverter With Wide-Range Power Flow Capability for Renewable Energy Applications

    Microsoft Academic Search

    Pengwei Sun; Chuang Liu; Jih-Sheng Lai; Chien-Liang Chen

    2012-01-01

    This paper presents a grid-tie control system for cascade dual-buck inverter with both active and reactive power flow capability in a wide range under two types of renewable energy sources. A fuel-cell power-conditioning system (PCS) is a Type I system with active power command generated by balance of plant of each unit; and photovoltaic or wind PCS is a Type

  3. Thermionic converter studies at Thermo Electron

    NASA Technical Reports Server (NTRS)

    Huffman, F. N.; Lieb, D.; Rufeh, F.

    1977-01-01

    The Thermionic Energy Converter (TEC) development program includes theoretical and experimental surface studies, diode evaluation, enhanced mode converter investigations and system studies, as well as materials fabrication and testing. The primary effort has been concentrated on increasing converter performance via improved electrodes. Diodes with oxide collectors (i.e., tungsten oxide, titanium oxide, zinc oxide and barium oxide) have provided the best performance. Emitters requiring reduced cesium pressure (such as oxygenated tungsten, lanthanum hexaboride, platinum and graphite) are being tested. Converter configurations using particle spacing are under investigation. Experiments with auxiliary electrode thermionic converters are in progress. Both silicon carbide and alloy hot shells (i.e., barriers to isolate the converter from the combustion environment) have been fabricated and tested.

  4. 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.

  5. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

    Skutt, Glenn; Sable, Dan; Leslie, Leonard; Graham, Shawn

    2012-01-01

    A document discusses power converters suitable for space use that meet the DSCC MIL-PRF-38534 Appendix G radiation hardness level P classification. A method for qualifying commercially produced electronic parts for DC-DC converters per the Defense Supply Center Columbus (DSCC) radiation hardened assurance requirements was developed. Development and compliance testing of standard hybrid converters suitable for space use were completed for missions with total dose radiation requirements of up to 30 kRad. This innovation provides the same overall performance as standard hybrid converters, but includes assurance of radiation- tolerant design through components and design compliance testing. This availability of design-certified radiation-tolerant converters can significantly reduce total cost and delivery time for power converters for space applications that fit the appropriate DSCC classification (30 kRad).

  6. Semen variables and sperm membrane protein profile of Saanen bucks (Capra hircus) in dry and rainy seasons of the northeastern Brazil (3°S).

    PubMed

    van Tilburg, M F; Salles, M G F; Silva, M M; Moreira, R A; Moreno, F B; Monteiro-Moreira, A C O; Martins, J A M; Cândido, M J D; Araújo, A A; Moura, A A A

    2015-05-01

    The Saanen is a highly productive breed, and for this reason, it has been raised in Brazil, but mostly under climate conditions completely different from where the breed originated. The objective of this study was to investigate variations in semen parameters and sperm membrane proteins from Saanen bucks (n?=?7) raised in Northeastern Brazil, during dry season (September, October, and November) and rainy season (March, April, and May). We showed that during the dry season, sperm motility, concentration, and the percentage of normal sperm decreased as compared to the rainy season. Rectal temperatures of bucks had no significant (p?>?0.05) variations during the dry and rainy seasons. However, temperatures of left and right skin testis were higher (p?bucks did not prevent a decrease in seminal parameters during the dry season. This deterioration may be related to reduced expression of proteins associated with important functions in sperm membrane. PMID:25086569

  7. Thermographic Analysis of a Bridge Power Converter

    NASA Astrophysics Data System (ADS)

    Anna, V. Andonova; Nikolay, L. Hinov

    2015-01-01

    Any loss of power in converters is dissipated as heat in the components of the circuit. The article presents a new approach to measuring heat dissipation in a bridge power converter with hard switches using infrared thermography. Parallel measurements by thermocouples have been carried out. The experimental results are compared and used from the both cases. The proposed approach can be used for various circuit implementations of the converters in a similar manner.

  8. 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

  9. 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.

  10. 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.

  11. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  12. Digital control for phase shift converter

    Microsoft Academic Search

    R. Etz; T. Patarau; D. Petreus; S. Daraban; D. Moga

    2012-01-01

    The development of intelligent microgrids with renewable energy sources increased significantly nowadays. The present paper examines and compares analog and digital control of a bidirectional phase shift converter in order to find out which is best suited to be used in intelligent microgrid applications. New small signal models for the direct and reverse power flow transfer modes of the converter

  13. Control strategy for a Teniente Converter

    Microsoft Academic Search

    L. G. Bergh; P. Chacana; C. Carrasco

    2005-01-01

    A diagnosis of the actual distributed control and measurements system for a Teniente Converter, processing copper concentrates, is presented. Besides the importance of this converter in Caletones Smelter, there is a number of unsolved problems related to lack of instrumentation, lack of process knowledge, odd operating practices, and lack of procedures to process data to aid management and operating decisions.

  14. Distributed electrical leads for thermionic converter

    DOEpatents

    Fitzpatrick, Gary O. (Livermore, CA); Britt, Edward J. (Cupertino, CA)

    1979-01-01

    In a thermionic converter, means are provided for coupling an electrical lead to at least one of the electrodes thereof. The means include a bus bar and a plurality of distributed leads coupled to the bus bar each of which penetrates through one electrode and are then coupled to the other electrode of the converter in spaced apart relation.

  15. 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.

  16. Passive Resonant Bidirectional Converter with Galvanic Barrier

    NASA Technical Reports Server (NTRS)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  17. 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

  18. 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.

  19. 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 ...

  20. RF digital-to-analog converter

    DOEpatents

    Conway, P.H.; Yu, D.U.L.

    1995-02-28

    A digital-to-analog converter is disclosed 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. 18 figs.

  1. 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.

  2. Experimental thermionic energy converter without enclosure: A molecular beam supplied converter

    Microsoft Academic Search

    L. Holmlid; K. Möller

    1984-01-01

    Experimental thermionic energy converters of an open type, i.e. with no closely located surrounding walls, as proposed here, have many advantages compared to conventional enclosed converters. Interactions with and problems of the enclosure do not interfere with the fundamental plasma and surface processes, which can be studied efficiently in an open converter, for example by mass spectrometry, optical spectroscopy, electron

  3. User's design handbook for a Standardized Control Module (SCM) for DC to DC Converters, volume 2

    NASA Technical Reports Server (NTRS)

    Lee, F. C.

    1980-01-01

    A unified design procedure is presented for selecting the key SCM control parameters for an arbitrarily given power stage configuration and parameter values, such that all regulator performance specifications can be met and optimized concurrently in a single design attempt. All key results and performance indices, for buck, boost, and buck/boost switching regulators which are relevant to SCM design considerations are included to facilitate frequent references.

  4. Boost matrix converters in clean energy systems

    NASA Astrophysics Data System (ADS)

    Karaman, Ekrem

    This dissertation describes an investigation of novel power electronic converters, based on the ultra-sparse matrix topology and characterized by the minimum number of semiconductor switches. The Z-source, Quasi Z-source, Series Z-source and Switched-inductor Z-source networks were originally proposed for boosting the output voltage of power electronic inverters. These ideas were extended here on three-phase to three-phase and three-phase to single-phase indirect matrix converters. For the three-phase to three-phase matrix converters, the Z-source networks are placed between the three-switch input rectifier stage and the output six-switch inverter stage. A brief shoot-through state produces the voltage boost. An optimal pulse width modulation technique was developed to achieve high boosting capability and minimum switching losses in the converter. For the three-phase to single-phase matrix converters, those networks are placed similarly. For control purposes, a new modulation technique has been developed. As an example application, the proposed converters constitute a viable alternative to the existing solutions in residential wind-energy systems, where a low-voltage variable-speed generator feeds power to the higher-voltage fixed-frequency grid. Comprehensive analytical derivations and simulation results were carried out to investigate the operation of the proposed converters. Performance of the proposed converters was then compared between each other as well as with conventional converters. The operation of the converters was experimentally validated using a laboratory prototype.

  5. Relevance of cryptic fishes in biodiversity assessments: A case study at Buck Island Reef National Monument, St. Croix

    USGS Publications Warehouse

    Smith-Vaniz, W.F.; Jelks, H.L.; Rocha, L.A.

    2006-01-01

    Because cryptic fishes are difficult to accurately survey, they are undersampled components of coral reef habitats, and their ecological roles have been generally ignored. Fifty-eight enclosed stations were sampled in shoreline, nearshore reef, lagoon, backreef, forereef, and bank/shelf habitats with an ichthyocide (rotenone) at Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands. Our samples included 55 families and 228 species, 60 previously unreported from St. Croix. Fish assemblages varied across habitat zones with the shoreline assemblage the most distinct. Only 8% of the species were present in all habitats. Multi-dimensional scaling plots of habitat characteristics and Bray-Curtis similarities of fish assemblages revealed similar patterns. Dominant and rare taxa are enumerated for each habitat sampled. Rotenone and visual census data are compared. While visual surveys accumulated more species per unit of effort, rotenone samples accumulated more species by area. Only 36% of the 228 species sampled with rotenone were visually detected, while 70% of the 115 species visually detected were also collected with rotenone. The use of rotenone is controversial but important for obtaining reasonably complete inventories of reef fishes. Misconceptions about rotenone and the advantages and limitations of alternative biodiversity assessment methods are discussed. ?? 2006 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.

  6. 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 ...

  7. 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 ...

  8. Radio frequency digital to analog converter

    E-print Network

    Luschas, Susan, 1975-

    2003-01-01

    Dynamic performance of high speed, high resolution digital-to-analog converters (DACs) is limited by distortion at the data switching instants. Inter-symbol interference (ISI), imperfect timing synchronization and clock ...

  9. Process for converting oxygenates to hydrocarbons

    SciTech Connect

    Tabak, S.A.

    1987-03-31

    A process is described for converting oxygenate feedstock to liquid hydrocarbons comprising: converting oxygenate feedstock predominantly to gasoline range hydrocarbons in a first reactor zone, in contact with ZSM-5 zeolite catalyst thereby producing a minor amount of excess isobutane; separating isobutane from the first reactor effluent; converting oxygenate feedstock predominantly to C/sub 2/-C/sub 5/ lower olefins in a second reactor zone in contact with zeolite catalyst, while maintaining sufficient production of C/sub 3/+ olefins in the second reactor zone to react with excess isobutane produced in the first reactor zone; separating an ethane rich stream from the second reactor olefinic effluent and further converting the ethene to heavier hydrocarbons in the first reactor zone; and alkylating the isobutane with C/sub 3/+ olefins in a third reactor zone in contact with an acid catalyst.

  10. Improvements in solid state radiographic converter screens.

    NASA Technical Reports Server (NTRS)

    Szepesi, Z.

    1972-01-01

    Description of two different kinds of solid-state radiographic converter screens which have been developed. After briefly reviewing the working principles of the solid-state image converter - a sandwich type structure consisting of a photoconductive layer and an electroluminescent layer with a semiconductive layer and a black layer between them, two different kinds of radiographic converter screens are described - a radiographic amplifier screen that can be used as a substitute for the fluoroscopic screen, and a radiographic storage screen that can be used instead of radiographic films. The construction of both kinds of converters is fundamentally the same, the only difference being in the sensing photoconductive material. The radiographic amplifier screen has a moderately fast response, while the radiographic storage screen displays the image long after the irradiation is stopped.

  11. 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 ...

  12. Waveguide mode converter and method using same

    DOEpatents

    Moeller, Charles P. (Del Mar, CA)

    1990-01-01

    A waveguide mode converter converts electromagnetic power being transmitted in a TE.sub.0n or a TM.sub.0n mode, where n is an integer, to an HE.sub.11 mode. The conversion process occurs in a single stage without requiring the power to pass through any intermediate modes. The converter comprises a length of circular corrugated waveguide formed in a multiperiod periodic curve. The period of the curve is selected to couple the desired modes and decouple undesired modes. The corrugation depth is selected to control the phase propagation constant, or wavenumbers, of the input and output modes, thereby preventing coherent coupling to competing modes. In one embodiment, both the period and amplitude of the curve may be selectively adjusted, thereby allowing the converter to be tuned to maximize the conversion efficiency.

  13. Converting Garbage to Gold: Recycling Our Materials.

    ERIC Educational Resources Information Center

    Chandler, William U.

    1984-01-01

    Recycling conserves energy, fights pollution and inflation, creates jobs, and improves the outlook for the future of materials. But converting a throwaway society to recycling will depend on finding good markets for waste paper and scrap metals. (RM)

  14. 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.

  15. 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

  16. 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

  17. Low arc drop hybrid mode thermionic converter

    NASA Technical Reports Server (NTRS)

    Shimada, K.

    1977-01-01

    The hybrid mode operation for the reduction of plasma drops is being investigated. This report discusses the results obtained from two molybdenum emitter converters. One converter had a molybdenum collector and the other a nickel collector. The molybdenum collector converter was operated in a hybrid mode (at an interelectrode distance of 1.7 mm) and produced a minimum barrier index of 1.96 eV at an emitter temperature of 1500 K. The arc drop was calculated to be 0.14 eV, using the published results for a molybdenum collector. On the other hand, the nickel collector converter was operated in a conventional ignited mode (at an interelectrode distance of 0.5 mm) and produced a minimum barrier index of 2.1 eV at an emitter temperature of 1700 K. It is tentatively concluded that a large-gap operation of the hybrid mode converter permits the diffusion of cesium ions to a distance in the order of one millimeter for an effective neutralization of electron space charge. By employing a low work function collector (1.55 eV) in a hybrid mode converter with an arc drop of 0.14 eV, it appears that a barrier index as low as 1.69 eV could be achieved.

  18. 78 FR 40132 - Wave Energy Converter Prize Administration Webinar

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-03

    ...Efficiency and Renewable Energy Wave Energy Converter Prize Administration Webinar AGENCY...tentatively titled, ``Wave Energy Converter Prize Administration''. The Office...prize competition related to wave energy converters. The WWPTO anticipates a...

  19. Advanced single-phase AC-DC converter using single-phase matrix converter topology

    Microsoft Academic Search

    R. Baharom; N. R. Hamzah; M. K. Hamzah

    2011-01-01

    This paper proposes advanced single-phase AC-DC converter using single-phase matrix converter (SPMC) topology incorporating with active power filter function. The topology is also capable of incorporating many other features for controlled rectifier operation that includes; bidirectional, regenerative and dual converter capabilities. The PWM technique was used to calculate the switch duty ratio to synthesize the output. Switch commutation arrangements were

  20. Stability analysis of converter-grid interaction using the converter input admittance

    Microsoft Academic Search

    Lennart Harnefors; Massimo Bongiorno; Stefan Lundberg

    2007-01-01

    A grid-connected power electronic converter can cause local instabilities when interacting other subsystems-particularly poorly damped resonances-that are electrically nearby. However, oscillations at a certain frequency cannot build up due to the converter if its differential input admittance has positive conductance (real part) at that frequency, since power is then dissipated. Input-admittance expressions for a voltage-source converter are derived in this

  1. 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.

  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. Thermionic converter for space reactor described

    NASA Astrophysics Data System (ADS)

    Cao, S.; Yang, J.

    1984-12-01

    Thermionic converters have many advantages as space reactors. During the past several years six experiments, four in-pile and two out-pile were conducted. Tandem converters consisting of three sections were tested in three of the in-pile experiments, which revealed that the peak power density was W = 2.4 W/square centrimeters, the electrode efficiency was eta = 4.2%, and the emitter temperature was T sub E - 1460 C. A single section converter was tested in the fourth in-pile experiment and it was found that W = 5.6 W/square centimeters, eta = 8%, T sub E = 1540 C. The two out-pile experiments indicated that for emitter temperature T sub E = 1600 C, the peak power density and electrode efficiency were equal to W = 7.8 W/square centimeters and eta = 12.7%, respectively.

  4. 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?

  5. 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.

  6. Combination solar photovoltaic heat engine energy converter

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.

    1987-01-01

    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.

  7. Hydrodynamic Performance of a Wave Energy Converter

    NASA Astrophysics Data System (ADS)

    Yang, Yingchen

    2010-11-01

    To harvest energy from ocean waves, a new wave energy converter (WEC) was proposed and tested in a wave tank. The WEC freely floats on the water surface and rides waves. It utilizes its wave-driven angular oscillation to convert the mechanical energy of waves into electricity. To gain the maximum possible angular oscillation of the WEC under specified wave conditions, both floatation of the WEC and wave interaction with the WEC play critical roles in a joint fashion. During the experiments, the submersion condition of the WEC and wave condition were varied. The results were analyzed in terms of the oscillation amplitude, stability, auto-orientation capability, and wave frequency dependency.

  8. A quadratic analog-to-digital converter

    NASA Technical Reports Server (NTRS)

    Harrison, D. C.; Staples, M. H.

    1980-01-01

    An analog-to-digital converter with a square root transfer function has been developed for use with a pair of CCD imaging detectors in the White Light Coronagraph/X-ray XUV Telescope experiment to be flown as part of the Internal Solar Polar Mission. It is shown that in background-noise-limited instrumentation systems a quadratic analog-to-digital converter will allow a maximum dynamic range with a fixed number of data bits. Low power dissipation, moderately fast conversion time, and reliability are achieved in the proposed design using standard components and avoiding nonlinear elements.

  9. Solar energy converter using surface plasma waves

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  10. Potential converter for laser-power beaming

    NASA Technical Reports Server (NTRS)

    Walker, Gilbert H.; Williams, Michael D.; Schuster, Gregory L.; Iles, Peter A.

    1991-01-01

    Future space missions, such as those associated with the Space Exploration Initiative (SEI), will require large amounts of power for operation of bases, rovers, and orbit transfer vehicles. One method for supplying this power is to beam power from a spaced based or Earth based laser power station to a receiver where laser photons can be converted to electricity. Previous research has described such laser power stations orbiting the Moon and beaming power to a receiver on the surface of the Moon by using arrays of diode lasers. Photovoltaic converters that can be efficiently used with these diode lasers are described.

  11. Efficient HVDC converter model for real time transients simulation

    Microsoft Academic Search

    S. Acevedo; L. R. Linares; J. R. Marti; Y. Fujimoto

    1999-01-01

    An efficient model has been developed to simulate high voltage direct current (HVDC) power converters in real-time transient simulators. Real time performance of 45 ?s per solution step has been achieved for a 12-pulse monopolar converter and 81 ?s for the bipolar converter using a single processor Pentium Pro 200 MHz desktop computer. The HVDC power converter model is solved

  12. 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.

  13. Convertible Shoes: Function, Fashion and Design

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students teams design and build shoe prototypes that convert between high heels and athletic shoes. They apply their knowledge about the mechanics of walking and running as well as shoe design (as learned in the associated lesson) to design a multifunctional shoe that is both fashionable and functional.

  14. Hybrid switch for resonant power converters

    DOEpatents

    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.

  15. Hydrostatic transmission development for wave energy converters

    Microsoft Academic Search

    Hoang Huu Tien; Dinh Quang Truong; Kyoung Kwan Ahn

    2011-01-01

    innovative approach for electric power conversion from the vast ocean wave energy. Here, a floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), which is shortened as HSTWEC, is proposed and designed to enhance the wave energy generation task during wave fluctuations. In this HSTWEC structure, the power take-off system (PTO) is a combination of the designed HST circuit and

  16. An innovative design of wave energy converter

    Microsoft Academic Search

    K. K. Ahn; D. Q. Truong; Hoang Huu Tien; Jong Il Yoon

    The aim of this research is to develop an innovative approach for electric power conversion of the vast ocean wave energy. A floating-buoy wave energy converter (WEC) using hydrostatic transmission (HST), which is shortened as HSTWEC, has been proposed to enhance the wave energy generation from wave fluctuations. In the HSTWEC device, the power take-off system (PTO) was combined with

  17. Catalytic converter for exhaust gas purification

    SciTech Connect

    Toryu, K.; Higashi, K.

    1984-07-10

    A catalytic converter is adapted to retard spark timing to increase the temperature of the converter catalyst when a temperature sensor within the converter senses low exhaust temperature. A vacuum advance mechanism is responsive to intake manifold vacuum conducted thereto via an intake vacuum passageway to advance spark timing for the engine. The temperature of exhaust gas from a catalytic converter for exhaust emissions is sensed. When the sensed temperature of the exhaust is below a predetermined value, a comparator outputs an actuation signal which is used to cause a solenoid valve to open an air passageway to admit atmospheric air into the vacuum advance mechanism so that spark timing will be retarded, thereby increasing the temperature of the catalyst. At least one of a transmission neutral switch, a throttle switch and a clutch switch connected in series may be provided in the circuit between the comparator and the solenoid valve for returning spark timing to a standard value when any of the switches is open. At least one of the intake vacuum passageway and the air passageways may be provided with a member for restricting the internal cross-sectional area of the associated passageway to obtain the desired spark timing relationship.

  18. Oscillations in a Collisionless Thermionic Converter

    Microsoft Academic Search

    V. I. Kuznetsov; A. Ya. Énder

    1973-01-01

    The frequency dependence of the imppedence of a thermionic converter ; vestigated in regimes in which the directed velocity of the electrons is large; ; frequencies higher than the plasma frequency are studied. It is shown that the ; excitation of electron lectrode spacing. Oscillations can be excited at ; frequencies far below the electron plasma frequency. An experimental study

  19. Operating mechanism of sheath in thermionic converters

    Microsoft Academic Search

    Yoshihiko Hirai

    1978-01-01

    The operating mechanism of the sheath in the thermionic converter was studied by simulation and experiment and the output current density vs. voltage characteristics were calculated. The following conclusions were obtained: (1) electrons emitted from the emitter are subject to expansion in their density distribution in the accelerating field of the sheath; (2) in the decelerating field, electrons are subject

  20. Converting Waste into Clean Renewable Fuel

    E-print Network

    ­ Waste and biomass gasification ­ Standard cleaning of synthesis gas ­ Ultra-deep cleaning of synthesis #12;InEnTec's Plasma Enhanced MelterTM Process Gasifier converts much of the organic material to synthesis gas Trash goes in here Plasma heating Resistive heating of inorganic materials in pool of molten

  1. 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.

  2. National Ignition Facility frequency converter development

    SciTech Connect

    Barker, C.E.; Auerbach, J.M.; Adams, C.H. [and others

    1996-12-09

    A preliminary error budget for the third harmonic converter for the National Ignition Facility (NIF) laser driver has been developed using a root-sum-square-accumulation of error sources. Such a budget sets an upper bound on the allowable magnitude of the various effects that reduce conversion efficiency. Development efforts on crystal mounting technology and crystal quality studies are discussed.

  3. Converting Your Lab from Verification to Inquiry

    NSDL National Science Digital Library

    Connie P. Russell

    2006-01-01

    This chapter offers insight into how to create laboratories that provide students with research experiences within the constraints of time, resources, and course formats that most faculty face. It provides a research-based rationale for investigative or inquiry-based labs; an example of their implementation in a large-enrollment, introductory course for mixed majors; and recommendations for converting labs.

  4. High power matrix converter for wind power generation applications

    Microsoft Academic Search

    Jun Kang; Noriyuki Takada; Eiji Yamamoto; Eiji Watanabe

    2011-01-01

    The matrix converter has many advantages in wind power system applications. Matrix converter is compact and highly efficient because it directly converts generated power from AC generator to AC grid without intermediate DC bus while conventional back-to-back converter systems requires many electrolytic capacitors in DC link bus which are bulky and have short life-time. Matrix converter has both motoring and

  5. A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

    SciTech Connect

    Kim, Heeje; Kim, Jongrak; Shin, Dongsul [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); Kim, Hosung; Lee, Kyungjun [Department of Electrical Engineering, Pusan National University, Jangjeon, Geumjeong, Busan 609-735 (Korea); New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea); Kim, Jonghyun; Yoo, Dongwook [New and Renewable Energy System Research Center, Korea Electro-technology Research Institute, 28-1, Sungju-dong Changwon-si, Kyungsannam-do, 641-120 (Korea)

    2010-08-15

    A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter. (author)

  6. Biranchinath Sahu, Student Member, IEEE, and Gabriel A. Rincn-Mora, Senior Member, IEEE Georgia Tech Analog and Power IC Design Laboratory

    E-print Network

    Rincon-Mora, Gabriel A.

    a novel low voltage, dual-mode, buck-boost converter IC targeted for dynamic supplies of linear RF power µsec. Index Terms--Buck-boost converter IC, integrated power management, dual-mode converter I (IC) design and implementation of a dual-mode, buck-boost converter to achieve high efficiency over

  7. 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

    USGS Publications Warehouse

    Mayor, P.A.; Rogers, C.S.; Hillis-Starr, Z.-M.

    2006-01-01

    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. ?? Springer-Verlag 2006.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. MAGIC: Model and Graphic Information Converter

    NASA Technical Reports Server (NTRS)

    Herbert, W. C.

    2009-01-01

    MAGIC is a software tool capable of converting highly detailed 3D models from an open, standard format, VRML 2.0/97, into the proprietary DTS file format used by the Torque Game Engine from GarageGames. MAGIC is used to convert 3D simulations from authoritative sources into the data needed to run the simulations in NASA's Distributed Observer Network. The Distributed Observer Network (DON) is a simulation presentation tool built by NASA to facilitate the simulation sharing requirements of the Data Presentation and Visualization effort within the Constellation Program. DON is built on top of the Torque Game Engine (TGE) and has chosen TGE's Dynamix Three Space (DTS) file format to represent 3D objects within simulations.

  13. 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.

  14. 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

  15. 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).

  16. Converting Centrifugal Chillers to HCFC-123

    E-print Network

    Siebert, B.

    Corporation successfully converted 15 centrifugal chillers to HCFC refrigerants on an ambitious schedule between April 1 and September 3, 1992. The conversions helped the company, a Denver based manufacturer of computer disk drive storage systems, meet a... in 1990. Working closely with the Denver district office of The Trane Company, manufacturer of nine of the 15 chillers, the company began formulating a CFC policy and examining options for replacing the CFC refrigerant in its chillers. The chillers...

  17. Serum angiotensin converting enzyme in pulmonary disease

    Microsoft Academic Search

    P. K. Rohatgi

    1982-01-01

    Synthetic acylated tripeptides, which may or may not be radiolabelled, are generally used as substrates for measuring serum\\u000a angiotensin converting enzyme (SACE) activity. The capillary endothelial cells are the major source of SACE in normals and\\u000a certain diseased states, however Gaucher’s cells in Gaucher’s disease and epithelioid cells in granulomatous disorders, including\\u000a sarcoidosis, are the major source of enzyme in

  18. Converting Frequency Responses to Daily Frequency

    Cancer.gov

    Frequency information on the DSQ in NHANES 2009-2010 was collected using a rate and time unit (e.g., 3 times per week). A different response format consisting of a set number of frequency categories is used in the self-administered paper questionnaire (link to questionnaire) ,. In both cases, the frequency responses are converted to a common unit of time, i.e. times per day.

  19. Aquifer tests and simulation of ground-water flow in Triassic sedimentary rocks near Colmar, Bucks and Montgomery Counties, Pennsylvania

    USGS Publications Warehouse

    Risser, Dennis W.; Bird, Philip H.

    2003-01-01

    This report presents the results of a study by the U.S. Geological Survey in cooperation with the U.S. Environmental Protection Agency to evaluate ground-water flow in Triassic sedimentary rocks near Colmar, in Bucks and Montgomery Counties, Pa. The study was conducted to help the U.S. Environmental Protection Agency evaluate remediation alternatives at the North Penn Area 5 Superfund Site near Colmar, where ground water has been contaminated by volatile organic solvents (primarily trichloroethene). The investigation focused on determining the (1) drawdown caused by separately pumping North PennWater Authority wells NP?21 and NP?87, (2) probable paths of groundwater movement under present-day (2000) conditions (with NP?21 discontinued), and (3) areas contributing recharge to wells if pumping from wells NP-21 or NP?87 were restarted and new recovery wells were installed. Drawdown was calculated from water levels measured in observation wells during aquifer tests of NP?21 and NP?87. The direction of ground-water flow was estimated by use of a three-dimensional ground-water-flow model. Aquifer tests were conducted by pumping NP?21 for about 7 days at 257 gallons per minute in June 2000 and NP?87 for 3 days at 402 gallons per minute in May 2002. Drawdown was measured in 45 observation wells during the NP?21 test and 35 observation wells during the NP?87 test. Drawdown in observation wells ranged from 0 to 6.8 feet at the end of the NP?21 test and 0.5 to 12 feet at the end of the NP?87 test. The aquifer tests showed that ground-water levels declined mostly in observation wells that were completed in the geologic units penetrated by the pumped wells. Because the geologic units dip about 27 degrees to the northwest, shallow wells up dip to the southeast of the pumped well showed a good hydraulic connection to the geologic units stressed by pumping. Most observation wells down dip from the pumping well penetrated units higher in the stratigraphic section that were not well connected to the units stressed by pumping. The best hydraulic connection to the pumped wells was indicated by large drawdown in observation wells that penetrate the water-bearing unit encountered below 400 feet below land surface in wells NP?21 and NP?87. The hydraulic connection between wells NP?21 (or NP?87) and observation wells in the southern area of ground-water contamination near the BAE Systems facility is good because the observation wells probably penetrate this water-bearing unit. A 3-dimensional, finite-difference, groundwater- flow model was used to simulate flow paths and areas contributing recharge to wells for current (2000) conditions of pumping in the Colmar area and for hypothetical situations of pumping suggested by the U.S. Environmental Protection Agency that might be used for remediation. Simulations indicate that under current conditions, ground water in the northern area of contamination near the former Stabilus facility moves to the northwest and discharges mostly to West Branch Neshaminy Creek; in the southern area of contamination near BAE Systems facility, ground water probably moves west and discharges to a tributary ofWest Branch Neshaminy Creek near well NP?21. Model simulations indicate that if NP?21 or NP?87 are pumped at 400 gallons per minute, groundwater recharge is likely captured from the southern area of contamination, but ground-water recharge from the northern area of contamination is less likely to be captured by the pumping. Simulations also indicate that pumping of a new recovery well near BAE Systems facility at 8 gallons per minute and two new recovery wells near the former Stabilus facility at a total of about 30 gallons per minute probably would capture most of the ground-water recharge in the areas where contamination is greatest.

  20. Conversion system for converting oxygenates to hydrocarbons

    SciTech Connect

    Tabak, S.A.

    1991-01-15

    This patent describes a process reactor system for converting oxygenate feedstock to liquid hydrocarbons. It comprises: first reactor means for converting oxygenate feedstock predominantly to gasoline range hydrocarbons in a first reactor zone, in contact with acid shape selective, medium pore zeolite catalyst thereby producing a minor amount of excess isobutane; means for separating isobutane from the first reactor effluent; second reactor means for converting oxygenate feedstock predominantly to C{sub 2}--C{sub 5} lower olefins in a second reactor zone in contact with zeolite catalyst, while maintaining sufficient production of C{sub 3}{sup +} olefins in the second reactor zone to react with excess isobutane produced in the first reactor zone; means for separating an ethene rich stream from the second reactor olefinic effluent; means for passing the ethene-rich stream to the first reactor zone for further conversion of ethene to heavier hydrocarbons; and alkylation reactor means for alkylating the isobutane with C{sub 3}{sup +} olefins in a third reactor zone in contact with an acid catalyst.

  1. 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…

  2. Modulation and control of matrix converter for aerospace application

    NASA Astrophysics Data System (ADS)

    Kobravi, Keyhan

    In the context of modern aircraft systems, a major challenge is power conversion to supply the aircraft's electrical instruments. These instruments are energized through a fixed-frequency internal power grid. In an aircraft, the available sources of energy are a set of variable-speed generators which provide variable-frequency ac voltages. Therefore, to energize the internal power grid of an aircraft, the variable-frequency ac voltages should be converted to a fixed-frequency ac voltage. As a result, an ac to ac power conversion is required within an aircraft's power system. This thesis develops a Matrix Converter to energize the aircraft's internal power grid. The Matrix Converter provides a direct ac to ac power conversion. A major challenge of designing Matrix Converters for aerospace applications is to minimize the volume and weight of the converter. These parameters are minimized by increasing the switching frequency of the converter. To design a Matrix Converter operating at a high switching frequency, this thesis (i) develops a scheme to integrate fast semiconductor switches within the current available Matrix Converter topologies, i.e., MOSFET-based Matrix Converter, and (ii) develops a new modulation strategy for the Matrix Converter. This Matrix Converter and the new modulation strategy enables the operation of the converter at a switching-frequency of 40kHz. To provide a reliable source of energy, this thesis also develops a new methodology for robust control of Matrix Converter. To verify the performance of the proposed MOSFET-based Matrix Converter, modulation strategy, and control design methodology, various simulation and experimental results are presented. The experimental results are obtained under operating condition present in an aircraft. The experimental results verify the proposed Matrix Converter provides a reliable power conversion in an aircraft under extreme operating conditions. The results prove the superiority of the proposed Matrix Converter technology for ac to ac power conversion regarding the existing technologies of Matrix Converters.

  3. 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...

  4. 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...

  5. 7 CFR 12.32 - Converted wetland identification criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Converted wetland identification criteria. 12.32 Section 12...Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland...

  6. 7 CFR 12.32 - Converted wetland identification criteria.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Converted wetland identification criteria. 12.32 Section 12...Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland...

  7. 7 CFR 12.32 - Converted wetland identification criteria.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Converted wetland identification criteria. 12.32 Section 12...Secretary of Agriculture HIGHLY ERODIBLE LAND AND WETLAND CONSERVATION Wetland Conservation § 12.32 Converted wetland...

  8. A Laboratory Study of X-to-Frequency Converters.

    ERIC Educational Resources Information Center

    Kartalopoulos, Stamatios V.

    1979-01-01

    Describes a laboratory demonstration that can be used to convert an analog quantity into frequency, which can then be converted into a binary measure using either an oscilloscope or a frequency counter. (MA)

  9. 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...

  10. 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

  11. 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

  12. Limiting efficiency of coupled thermal and photovoltaic converters

    Microsoft Academic Search

    Antonio Luque; Antonio Mart??

    1999-01-01

    This paper presents a general energetic and entropic analysis of ideal photovoltaic and solar-thermal converters. Its purpose is to determine the efficiency limit when both types of converters operate together (hybrid converters). It has been found that, while in practical cases hybrid converters may give very high efficiency (61.7% vs. 40.0% of the solar thermal at 500K and 40.7% of

  13. 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.

  14. A transient model for a cesium vapor thermionic converter. [Cs

    SciTech Connect

    El-Genk, M.S.; Murray, C.S.; Chaudhuri, S. (Institute for Space Nuclear Power Studies, Department of Chemical and Nuclear Engineering, The University of New Mexico, Albuquerque, New Mexico (USA))

    1991-01-10

    This paper presents an analytical model for simulating the transient and steady-state operation of cesium vapor thermionic converters. A parametric analysis is performed to assess the transient response of the converter to changes in fission power and width of interelectrode gap. The model optimizes the converter performance for maximum electric power to the load.(AIP)

  15. Hybrid predictive modeling and simulation of the Teniente converter

    Microsoft Academic Search

    Schaaf Max; Cipriano Aldo

    2008-01-01

    The principal copper pyrometallurgical technology employed in Chile is the Teniente converter (TC). The smelting and converting processes involve complex dynamics with strong interactions among manipulated variables, state variables, and product characteristics. Furthermore, the converter products are periodically extracted in a semi-continuous process. Previous applications of model predictive control in TC operation have shown good performance. The recent development of

  16. Thermionic converter plasma analysis. Final report Jan 71Apr 72

    Microsoft Academic Search

    McCandless

    1972-01-01

    This study develops an analysis of thermionic converter sheaths and weakly collisional thermionic converter plasmas. The analysis of thermionic converter sheaths is accomplished through the numerical solution of Poisson's equation and the Vlasov equations for electrons and ions in one dimensional planar geometry subject to half Maxwellian boundary conditions. The analysis considers monotonic accelerating and retarding sheaths and the class

  17. A new soft switching high step-up converter

    Microsoft Academic Search

    M. Delshad; M. Zamani Sedeh

    2011-01-01

    In this paper a high step-up soft switching converter is presented. The proposed converter consists of a flyback transformer for increasing voltage gain and an active clamp circuit for providing ZVS conditions for all switches. In this converter the secondary of transformer is rectified by a voltage multiplier which is connected series with output and increase voltage gain of proposed

  18. 40 CFR 89.317 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false NOX converter check. 89.317 Section 89.317...Equipment Provisions § 89.317 NOX converter check. (a) Prior to its introduction...analyzer shall be checked for NO2 to NO converter efficiency. Figure 2 in appendix...

  19. 40 CFR 90.319 - NOX converter check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false NOX converter check. 90.319 Section 90.319 ...Equipment Provisions § 90.319 NOX converter check. (a) The efficiency of the converter used for the conversion of NO2 to...

  20. A new bidirectional isolated converter for grid connection

    Microsoft Academic Search

    Myoungho Kim; Anno Yoo; Seung-Ki Sul

    2010-01-01

    This paper proposes a bidirectional isolated AC-AC converter for grid connection of various loads or energy sources. The converters can be utilized for interfacing renewable energy sources to the grid as well as traditional motor drives. It does not employ any line-frequency transformer, large electrolytic capacitors, and inductors to diminish the volume and enhance the reliability of the converter. Instead,

  1. Interaction between PEM Fuel Cells and Converters for AC Integration

    Microsoft Academic Search

    Diego Dias Marquezini; Ricardo Quadros Machado; Felix Alberto Farret

    2007-01-01

    This paper discusses the interaction between fuel cells (FC) and converters as a cause of great concern among power electronics designers. It is shown that internal surges due to such interaction may be decisive for new design of powerful converters for distribution systems As the number of such converters has increased a lot in the last few years the fuel

  2. 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

  3. Pneumatic manipulators for interrupting converter-slag flow

    Microsoft Academic Search

    V. V. Tochilkin

    2007-01-01

    686 Various methods of stopping slag flow are used to ensure the required metal quality when casting converter steel. One of the most effective is to use manipulators mounted next to the converter that cut off the slag flow by means of a ball plug [1]. In the oxygen-converter shop at Magnitogorsk Metallurgical Works, the manipulator used for this purpose

  4. Digital PWM Controller and Current Estimator for A Low-Power Switching Converter

    E-print Network

    Prodiæ, Aleksandar

    reliability, easier system integration, and possibility to include various performance enhancements is the non-inverting buck-boost shown in Fig. 1. This topology has only two passive components and can work on a 26 MIPS, 16-bit fixed-point digital signal processor. Intended for motor control applications, it has

  5. Voltage balanced multilevel voltage source converter system

    SciTech Connect

    Peng, F.Z.; Lai, J.S.

    1997-07-01

    Disclosed is a voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means. 15 figs.

  6. Voltage balanced multilevel voltage source converter system

    DOEpatents

    Peng, Fang Zheng (Oak Ridge, TN); Lai, Jih-Sheng (Knoxville, TN)

    1997-01-01

    A voltage balanced multilevel converter for high power AC applications such as adjustable speed motor drives and back-to-back DC intertie of adjacent power systems. This converter provides a multilevel rectifier, a multilevel inverter, and a DC link between the rectifier and the inverter allowing voltage balancing between each of the voltage levels within the multilevel converter. The rectifier is equipped with at least one phase leg and a source input node for each of the phases. The rectifier is further equipped with a plurality of rectifier DC output nodes. The inverter is equipped with at least one phase leg and a load output node for each of the phases. The inverter is further equipped with a plurality of inverter DC input nodes. The DC link is equipped with a plurality of rectifier charging means and a plurality of inverter discharging means. The plurality of rectifier charging means are connected in series with one of the rectifier charging means disposed between and connected in an operable relationship with each adjacent pair of rectifier DC output nodes. The plurality of inverter discharging means are connected in series with one of the inverter discharging means disposed between and connected in an operable relationship with each adjacent pair of inverter DC input nodes. Each of said rectifier DC output nodes are individually electrically connected to the respective inverter DC input nodes. By this means, each of the rectifier DC output nodes and each of the inverter DC input nodes are voltage balanced by the respective charging and discharging of the rectifier charging means and the inverter discharging means.

  7. Solid state transport-based thermoelectric converter

    DOEpatents

    Hu, Zhiyu

    2010-04-13

    A solid state thermoelectric converter includes a thermally insulating separator layer, a semiconducting collector and an electron emitter. The electron emitter comprises a metal nanoparticle layer or plurality of metal nanocatalyst particles disposed on one side of said separator layer. A first electrically conductive lead is electrically coupled to the electron emitter. The collector layer is disposed on the other side of the separator layer, wherein the thickness of the separator layer is less than 1 .mu.m. A second conductive lead is electrically coupled to the collector layer.

  8. Prototype of Free Piston Stirling Converter for Household Use

    NASA Astrophysics Data System (ADS)

    Hoshino, Takeshi; Yoshihara, Shoichi; Akazawa, Teruyuki; Murao, Keiji

    A test model of a free piston Stirling engine (FPSE) converter was developed as a heat-to-electricity power converter for a demonstration of solar heat energy utilization at the Japan Aerospace Exploration Agency, for future aerospace applications. The target performance of the converter was 200 W electrical power output and 20% overall efficiency. A bench test of the converter was conducted to evaluate performance. The converter showed good performance as expected. In addition, the characteristics of the FPSE were investigated. Based on these achievements, prototype models of the FPSE for household use were designed and tested as part of a project supported by the New Energy and Industrial Technology Development Organization.

  9. Input-current shaped ac to dc converters

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The problem of achieving near unity power factor while supplying power to a dc load from a single phase ac source of power is examined. Power processors for this application must perform three functions: input current shaping, energy storage, and output voltage regulation. The methods available for performing each of these three functions are reviewed. Input current shaping methods are either active or passive, with the active methods divided into buck-like and boost-like techniques. In addition to large reactances, energy storage methods include resonant filters, active filters, and active storage schemes. Fast voltage regulation can be achieved by post regulation or by supplementing the current shaping topology with an extra switch. Some indications of which methods are best suited for particular applications concludes the discussion.

  10. 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.

  11. 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.

  12. Converting CSV Files to RKSML Files

    NASA Technical Reports Server (NTRS)

    Trebi-Ollennu, Ashitey; Liebersbach, Robert

    2009-01-01

    A computer program converts, into a format suitable for processing on Earth, files of downlinked telemetric data pertaining to the operation of the Instrument Deployment Device (IDD), which is a robot arm on either of the Mars Explorer Rovers (MERs). The raw downlinked data files are in comma-separated- value (CSV) format. The present program converts the files into Rover Kinematics State Markup Language (RKSML), which is an Extensible Markup Language (XML) format that facilitates representation of operations of the IDD and enables analysis of the operations by means of the Rover Sequencing Validation Program (RSVP), which is used to build sequences of commanded operations for the MERs. After conversion by means of the present program, the downlinked data can be processed by RSVP, enabling the MER downlink operations team to play back the actual IDD activity represented by the telemetric data against the planned IDD activity. Thus, the present program enhances the diagnosis of anomalies that manifest themselves as differences between actual and planned IDD activities.

  13. Ultraviolet converter transients induced by electrons

    NASA Technical Reports Server (NTRS)

    Kernell, R. L.; Becher, J.; Reft, C. S.

    1984-01-01

    The output of ultraviolet converters typically used in satellite astronomy was monitored during irradiation with electrons from a sealed SR-90 source which approximated the peak flux in earth's outer electron belt. The signal induced by irradiation was attributed to two mechanisms: (1) photoelectrons resulting from photons created in the MgF2 window and (2) the direct impact of electrons on the phosphor. For irradiation at about 1 x 10 to the 7th e/sq cm sec, these two effects produced signals which were, in order of magnitude, the same as those produced by an incident UV flux (254 nm) of 10 to the 8th and 10 to the 7th photons/sq cm sec, respectively. In addition, the induced signal was investigated as a function of electron energy by irradiating another converter with 0.4-1.8-MeV electrons from a Van de Graaff. These results suggest that the dominant contribution to the electron-induced signal is Cerenkov photon production in the MgF2 window.

  14. The angiotensin converting enzyme and blood pressure in Jamaicans.

    PubMed

    Forrester, T; McFarlane-Anderson, N; Bennett, F I; Wilks, R; Cooper, R; Rotimi, C; Morrison, L; Ward, R

    1997-05-01

    An insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme gene influences the level of serum angiotensin converting enzyme activity and has been associated with risk of several cardiovascular conditions. The relationship to blood pressure remains uncertain, however. We conducted a population-based survey in Kingston, Jamaica, to examine the association between angiotensin converting enzyme genotype, angiotensin converting enzyme serum activity and blood pressure. Serum angiotensin converting enzyme activity was measured and genotyping performed for the I/D polymorphism in 500 community residents. The overall prevalence of the D allele was 59.3%. Angiotensin converting enzyme genotype was not significantly related to blood pressure (P = .16), although it did influence angiotensin-converting enzyme activity, leading to an increase of 35% among individuals with the DD as compared with II genotype. Angiotensin converting enzyme levels were significantly higher in hypertensives as compared with normotensives (P < .05). A modest correlation was observed between blood pressure and angiotensin converting enzyme activity among untreated individuals (r = 0.11; P = .04), although this did not persist in multivariate analysis. A relationship between body mass index and angiotensin converting enzyme activity was identified in both men and women that was independent of genotype. These data demonstrate findings among blacks which are consistent with other studies and suggest a relationship between angiotensin converting enzyme genotype, and serum activity which is influenced by both genetic and environmental factors. The potential role of ACE on blood pressure control in the population remains uncertain. PMID:9160762

  15. Converting or not converting to organic farming in Austria:Farmer types and their rationale

    Microsoft Academic Search

    Ika Darnhofer; Walter Schneeberger; Bernhard Freyer

    2005-01-01

    Reasons for converting to organic farming have been studied in a number of instances. However, the underlying rationale that motivates the behavior is not always made clear. This study aims to provide a detailed picture of farmers decision-making and illustrate the choice between organic and conventional farm management. Based on 21 interviews with farmers, a decision-tree highlighting the reasons and

  16. Combination acoustical muffler and exhaust converter

    SciTech Connect

    Nitz, A.E.

    1982-11-30

    A combination acoustical muffler and exhaust converter for use with internal combustion engines, comprising an elongated hollow cylinder adapted to be connected to a source of exhaust gas, screen means positioned at a plurality of longitudinally spaced locations within said cylinder for partitioning the cylinder into a plurality of chambers arranged in series flow relation with each other and with respect to the flow of exhaust gas through said cylinder, the screens having a silencing action on said exhaust gas, magnet means in one of said chambers for exerting a magnetic pressure on the gas passing therethrough to serve to separate ferrous particles from the exhaust gas stream, a packing material of mineral material, such as mineral wool, in another of said chambers for condensing moisture in said exhaust gas and for removing hydrocarbon therefrom, and a material such as a ceramic material of an extremely fine porous nature, in still another of said chambers for removing carbon monoxide from said exhaust gas.

  17. Angiotensin converting enzyme inhibition and the kidney

    NASA Technical Reports Server (NTRS)

    Hollenberg, N. K.

    1988-01-01

    Angiotensin II (Ang II) induces a marked reduction in renal blood flow at doses well below those required to induce a pressor response, and as blood flow falls there is a decline in glomerular filtration rate and sodium excretion. This striking sensitivity of the renal blood supply led many workers to consider the possibility that angiotensin functions as a local renal hormone. As angiotensin converting enzyme (ACE) was found in particular abundance in the lung, it seemed reasonable to suspect that most of the conversion occurred there, and that the function of Ang II would be primarily systemic, rather than intrarenal. In this review, I will explore the evidence that has accumulated on these two possibilities, since they have important implications for our current understanding of normal kidney function and derangements of kidney function in disease.

  18. Graphene optical-to-thermal converter

    NASA Astrophysics Data System (ADS)

    Manjavacas, Alejandro; Thongrattanasiri, Sukosin; Greffet, Jean-Jacques; de Abajo, F. Javier García

    2014-11-01

    Infrared plasmons in doped graphene nanostructures produce large optical absorption that can be used for narrow-band thermal light emission at tunable frequencies that strongly depend on the doping charge. By virtue of Kirchhoff's law, thermal light emission is proportional to the absorption, thus resulting in narrow emission lines associated with the electrically controlled plasmons of heated graphene. Here, we show that realistic designs of graphene plasmonic structures can release over 90% of the emission through individual infrared lines with 1% bandwidth. We examine anisotropic graphene structures in which efficient heating can be produced upon optical pumping tuned to a plasmonic absorption resonance situated in the blue region relative to the thermal emission. An incoherent thermal light converter is thus achieved. Our results open a radically different approach for designing tunable nanoscale infrared light sources.

  19. Converting low dose radiation to redox signaling.

    PubMed

    Pristov, Jelena Bogdanovi?; Spasi?, Mihajlo; Spasojevi?, Ivan

    2013-02-01

    In contrast to the damaging effects of high doses, low dose radiation (UV, gamma) has been reported to provoke constructive changes in plants. However, the mechanisms by which plants recognize and respond to low dose radiation are not understood. We have shown recently that polygalacturonic acid, cell wall polysaccharide, converts the highly reactive product of radiation - hydroxyl radical into superoxide which may be further dismutated to hydrogen peroxide. Superoxide has been proposed to act as a signaling molecule, while hydrogen peroxide is known to be the key species in redox signaling cascades which are involved in the regulation of various physiological processes. Hence we propose that polygalacturonic acid may operate as radiation-signaling convertor. The outlined principles of radiation-sensing could also be valid for mammalian cells, with some other molecules mediating the conversion. PMID:23299433

  20. Mechanical vibration to electrical energy converter

    DOEpatents

    Kellogg, Rick Allen (Tijeras, NM); Brotz, Jay Kristoffer (Albuquerque, NM)

    2009-03-03

    Electromechanical devices that generate an electrical signal in response to an external source of mechanical vibrations can operate as a sensor of vibrations and as an energy harvester for converting mechanical vibration to electrical energy. The devices incorporate a magnet that is movable through a gap in a ferromagnetic circuit, wherein a coil is wound around a portion of the ferromagnetic circuit. A flexible coupling is used to attach the magnet to a frame for providing alignment of the magnet as it moves or oscillates through the gap in the ferromagnetic circuit. The motion of the magnet can be constrained to occur within a substantially linear range of magnetostatic force that develops due to the motion of the magnet. The devices can have ferromagnetic circuits with multiple arms, an array of magnets having alternating polarity and, encompass micro-electromechanical (MEM) devices.

  1. Phase difference-to-voltage converter

    NASA Astrophysics Data System (ADS)

    Borghesani, A. F.

    1989-07-01

    A phase difference-to-voltage converter has been developed in order to measure and to monitor the phase angle ? between the rotating magnetic field and the disk magnetization in the recently developed rotating magnetic disk viscometer. The circuit described here shows a very good linearity (the nonlinearity has been experimentally found to be well ?50 p.p.m.), high resolution (fractional phase changes as low as ??/??10-4 can be detected), very high short-term stability (1/V??V?/?T ?10 p.p.m./°C), very good long-term stability (?V?/V? ?50 p.p.m. over several months), and a rapid response even at the low frequencies (0.5-30 Hz) used in the viscometer.

  2. Binary to binary coded decimal converter

    NASA Technical Reports Server (NTRS)

    Miller, A. J. (inventor)

    1978-01-01

    A binary coded input signal is converted to a binary coded decimal signal having N decades by employing N four bit shift registers. The bits of the input signal are sequentially supplied, in order, to the least significant position of the register for the units decade, with the most significant bit of the input signal being applied to the units register first. Each of the registers includes a right shift-parallel load mode control input terminal. In response to the sum of the values stored in each register and the binary value 0011 being less than the binary value 1000, the mode control input terminal is activated to shift the register contents one bit to the right. In response to the sum being greater than 1000, the mode control input terminal is activated to load the sum into the register.

  3. INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS Int. J. Circ. Theor. Appl. 2003; 31:555570 (DOI: 10.1002/cta.250)

    E-print Network

    Tse, Chi K. "Michael"

    -boost and boost converters. The resulting dual converters operate in the discontinuous capacitor voltage mode on cascade of boost and buck converters [1], (b) Ã?Cuk equivalence and (c) dual of the Ã?Cuk equivalence (new with an application of duality transformation to conventional discontinuous- conduction-mode buck, buck

  4. 2342 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 39, NO. 12, DECEMBER 2004 A 4-A Quiescent-Current Dual-Mode Digitally

    E-print Network

    Sanders, Seth

    -Current Dual-Mode Digitally Controlled Buck Converter IC for Cellular Phone Applications Jinwen Xiao, Student. Sanders, Member, IEEE Abstract--This paper describes a dual-mode digitally controlled buck converter IC-quiescent-power dual-mode digitally controlled buck converter IC for cellular phone applications. While the cellular

  5. A new battery charger/discharger converter. [for spacecraft application

    NASA Technical Reports Server (NTRS)

    Middlebrook, R. D.; Cuk, S.; Behen, W.

    1978-01-01

    A new optimum topology dc-to-dc switching converter is extended to provide bidirectional current flow. The resulting two-quadrant converter can be employed to eliminate the discontinuous current mode in normal unidirectional applications, but is especially suited for spacecraft battery conditioning as a charge-discharge regulator in place of the conventional separate converters. Implementation of the control features and the battery charge current and voltage limits are discussed.

  6. Torcrete mix of basic composition for converter lining

    Microsoft Academic Search

    E. V. Sidorov; Yu. N. Kochubeev; Yu. A. Borisova; E. V. Murashko; N. A. Bosyakova

    2011-01-01

    Results are presented for a laboratory study of the substance composition of a periclase-carbon torcrete mix for restoring\\u000a a converter lining, comparative methods for testing a torcrete mix under laboratory conditions, and the main production parameters\\u000a for a torcrete mix under existing production conditions. Industrial tests are performed in the converter section of the OAO\\u000a MMK oxygen-converter workshop. The life

  7. Investigation of a new cascade-of-resonators ?-? converter configuration

    Microsoft Academic Search

    Yvan Botteron; Behrouz Nowrouzian; A. T. G. Fuller; L. F. Choy

    1998-01-01

    In the past, a number of bandpass ?-? a converter configurations have appeared in the literature. Among these, there are two configurations which are of particular practical interest: The cascade-of-integrators and cascade-of-resonators ?-? a converters. This paper is concerned with an investigation of a new cascade-of-resonators bandpass ?-? converter,which combines the main salient features of the latter two configurations. These

  8. Ion trapping in the emitter sheath in thermionic converters

    Microsoft Academic Search

    Lennart Lundgren

    1985-01-01

    The effect of ion trapping in the emitter sheath in ignited thermionic converters is studied. The ion trapping prevents the emitter-sheath barrier from being higher than approximately 0.1 eV, when the current decreases in the converter. This gives a condition for the constriction of the arc. I-V curves are calculated for an ignited thermionic converter with a hydrodynamic plasma theory

  9. Gyrotron internal mode converter reflector shaping from measured field intensity

    Microsoft Academic Search

    Douglas R. Denison; Tak Sum Chu; Michael A. Shapiro; Richard J. Temkin

    1999-01-01

    We present the formulation and experimental results of a new approach to designing internal mode converter reflectors for high-power gyrotrons. The method employs a numerical phase retrieval algorithm that reconstructs the field in the mode converter from intensity measurements, thus accounting for the true field structure in shaping the beam-forming reflectors. An outline for designing a four-reflector mode converter is

  10. 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.

  11. DC-DC converters for electric vehicle applications

    Microsoft Academic Search

    Dakshina M. Bellur; Marian K. Kazimierczuk

    2007-01-01

    An integral part of any modern day electric vehicle is power electronic circuits (PECs) comprising of DC-AC inverters and DC-DC converters. A DC-AC inverter supplies the high power electric motor and utility loads such as air-conditioning system, whereas a DC-DC converter supplies conventional low-power, low-voltage loads. However, the need for high power bidirectional DC- DC converters in future electric vehicles

  12. High-power converter systems for high-speed generators

    Microsoft Academic Search

    P. Kollensperger; C. Meyer; U. Schwarzer; S. Schroder; R. W. De Doncker

    2005-01-01

    For grid connection of high-speed gas-turbines, converters can be used to eliminate the otherwise mandatory gearbox. Compared to standard drives, different requirements are imposed on the converter. In this paper, the application of different converter types for a typical gas-turbine generator system are investigated. After selecting suitable topologies and devices, the expected system power losses are calculated using a simulation

  13. Modular converter system reliability & performance analysis in design

    Microsoft Academic Search

    Tieling Zhang; Abdullah Zain

    2010-01-01

    Converter system plays an important role in power drive train of a wind turbine. In order to achieve higher reliability, the modular concept is popularly utilized in converter system design in modern wind turbines. A converter module can be a channel composed of AC\\/DC\\/AC or a module composed of AC\\/DC or DC\\/AC. AC\\/DC module can be used on either generator

  14. 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

  15. Integrated Solar Power Converters: Wafer-Level Sub-Module Integrated DC/DC Converter

    SciTech Connect

    None

    2012-02-09

    Solar ADEPT Project: CU-Boulder is developing advanced power conversion components that can be integrated into individual solar panels to improve energy yields. The solar energy that is absorbed and collected by a solar panel is converted into useable energy for the grid through an electronic component called an inverter. Many large, conventional solar energy systems use one, central inverter to convert energy. CU-Boulder is integrating smaller, microinverters into individual solar panels to improve the efficiency of energy collection. The University’s microinverters rely on electrical components that direct energy at high speeds and ensure that minimal energy is lost during the conversion process—improving the overall efficiency of the power conversion process. CU-Boulder is designing its power conversion devices for use on any type of solar panel.

  16. Coal-fired furnace for testing of thermionic converters

    NASA Astrophysics Data System (ADS)

    1980-10-01

    The development of thermionic converter technology has progressed to make near-term applications such as the thermionic topping of a pulverized coal-fired central station powerplant. Up to now, thermionic converters have been flame tested using natural gas as fuel. A test furnace is required for evaluation of thermionic converters in a coal-fired environment. The design and costs of a facility which adapts a coal-fired furnace for thermionic converter testing are discussed. Such a facility would be exempt from air pollution regulations because of its low firing rate.

  17. 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.

  18. AC\\/DC\\/AC converter based on parallel AC\\/DC and cascaded multilevel DC\\/AC converter

    Microsoft Academic Search

    Shweta Gautam; Anil Kumar Yadav; Rajesh Gupta

    2012-01-01

    This paper presents a single phase AC\\/DC\\/AC converter based on parallel AC\\/DC and cascaded multi-level DC\\/AC Converter. For a two-cell AC\\/DC\\/AC converter, two units of full-bridges are connected in parallel and two units of half-bridges are connected in cascade. It is proposed that instead of using two separate control loops of DC link voltages at the AC to DC conversion

  19. 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

  20. Novel Modulation Method for Multidirectional Matrix Converter

    PubMed Central

    Misron, Norhisam; Aris, Ishak Bin; 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