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1

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

2

Discontinuous Buck Converter  

NSDL National Science Digital Library

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

2009-11-19

3

Bidirectional buck boost converter  

DOEpatents

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.

Esser, Albert Andreas Maria (Niskayuna, NY)

1998-03-31

4

Bidirectional buck boost converter  

DOEpatents

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.

Esser, A.A.M.

1998-03-31

5

Buck-boost integrated forward converter  

Microsoft Academic Search

An integrated converter is a synthesized converter based on the overall system integration, which is simplified by the system objective and can implement the system functions similar to the discrete converters. An integrated converter consists of converter sets; each converter set has a special function defined by the designer. A family of DC\\/DC buck boost based integrated rectifier with two

Z. Nie; A. Emadi

2005-01-01

6

Hybrid modeling and control for buck-boost switching converters  

Microsoft Academic Search

The buck-boost switching converter is represented as a hybrid automaton model. The control problem of buck-boost switching converters is simplified to a guard selection problem. Meanwhile, a new hybrid control scheme is proposed to regulate the output voltage of a buck-boost DC-DC switching converter. The scheme covers a wide operating range under various load and line disturbances. In Comparing the

Ma Hongbo; Feng Quanyuan

2009-01-01

7

The multi-frequency small-signal model for buck and multiphase interleaving buck converters  

Microsoft Academic Search

This paper introduces a multi-frequency small-signal model for buck and multiphase interleaving buck converters. Including the influences from the sideband-frequency components generated by the pulse-width modulation (PWM), this model is applicable beyond half of the switching frequency. In voltage-mode-controlled buck converters, the proposed model predicts the measured phase delay, while the conventional average model fails to explain this phenomenon. With

Yang Qiu; Ming Xu; Kaiwei Yao; Juanjuan Sun; Fred C. Lee

2005-01-01

8

A robust second order sliding mode controller for Buck converter  

Microsoft Academic Search

A robust second order sliding mode control is used for Buck converter. After building the model of Buck circuit, the Twisting Algorithm is designed, which is based on relative degree of sliding mode control. The second order sliding mode not only reserves advantages of traditional sliding mode: robustness, but also eliminates the chattering problem. By comparing PID control with second

Huangfu Yigeng; Ma Ruiqing; Xie En; Abdellatif Miraoui

2010-01-01

9

Buck-Boost Converter Associated with Active Clamp Forward Converter for PV Power System  

Microsoft Academic Search

This paper presents an LED lighting system with a PV source. The circuit structure of the proposed system adopts buck-boost converter associated with forward converter. In this research, buck-boost converter is used as a charger for charging battery, and forward converter with active clamp circuit is adopted to drive LED lighting, and to respectively recover and reset energies stored in

S.-Y. Tseng; W.-C. Chen; Y.-J. Li; J.-S. Kuo

2007-01-01

10

Three-Level ZVS Active Clamping PWM for the DC–DC Buck Converter  

Microsoft Academic Search

This paper presents the study of a dc-dc buck converter with three-level buck clamping (buck-buck), zero-voltage switching (ZVS), active clamping, and constant-frequency pulsewidth modulation (PWM). Other ZVS dc-dc converter topologies that employ three-level switching cells are introduced, and their steady-state dc gain is analyzed. This analysis shows that the buck-buck converter has characteristics that warrant a more detailed study. A

Jean Paulo Rodrigues; A. J. Perin; S. A. Mussa; M. L. Heldwein

2009-01-01

11

Bidirectional converter with buck\\/forward active clamp  

Microsoft Academic Search

This paper presents a bi-directional converter with a buck\\/forward active clamp, which can be used in 360 V dc-link and 100 V battery of a dc generation PV system. This topology can achieve turn-on and turn-off zero-current-transition (ZCT). In buck operation mode, the converter is operated with synchronous rectification and with an active clamp, which is realized with a forward

T.-F. Wu; T.-M. Chen; Y.-D. Chang; C.-H. Chang

2009-01-01

12

THE EFFECTS OF COUPLED INDUCTORS IN PARALLEL INTERLEAVED BUCK CONVERTERS  

Microsoft Academic Search

Interleaved switching and coupled inductors are proven methods for reducing DC-DC converter output ripple. This paper furthers discussions of these techniques to arrangements of many buck converters connected in parallel. The different possible arrangements of the DC-DC converters are discussed and criteria for fair comparisons between them are chosen. The effects of interleaved switching on ripple values are presented and

Paul Sernia; David Finn; Geoff Walker

13

Computer simulations of optimum boost and buck-boost converters  

NASA Technical Reports Server (NTRS)

The development of mathematicl models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight annd loss profiles of various semiconductor components and magnetics as a function of the switching frequency.

Rahman, S.

1982-01-01

14

Reconfigurable digital controller for a buck converter based on FPGA  

Microsoft Academic Search

This paper presents a complete digitally controlled dc–dc buck converter performed by FPGA circuitry. All tasks, analog to digital conversion, control algorithm and pulse width modulation, were implemented in the FPGA. This approach enables high-speed dynamic response and programmability by the controller, without external passive components. In addition, the controller’s structure can be easily changed without external components. The applied

Miro Milanovic; Mitja Truntic; Primoz Slibar; Drago Dolinar

2007-01-01

15

Control-loop bandwidth limitations for multiphase interleaving buck converters  

Microsoft Academic Search

To investigate the relationship between the control-loop bandwidth and the switching frequency, this paper introduces a multi-frequency small-signal model for multiphase interleaving buck converters. Including the influences from the frequency components generated by the pulse-width modulation schemes, this model is applicable beyond half the switching frequency, which is where the average model loses its validity. For voltage-mode control, both cases

Yang Qiu; Kaiwei Yao; Yu Meng; Ming Xu; Fred C. Lee; Mao Ye

2004-01-01

16

Interleaved Buck Converters Based on Winner-Take-All Switching  

Microsoft Academic Search

This paper studies basic interleaved buck converters using a switching rule based on a winner-take-all principle. As the parameters are selected suitably, the system can realize multiphase synchronization automatically which is convenient for the ripple reduction of the output current. As the parameters vary, the system exhibits a variety of synchronous phenomena. Using the piecewise-constant model, we give the parameter

Toshimichi Saito; S. Tasaki; H. Torikai

2005-01-01

17

Passive component analysis in interleaved buck converters  

Microsoft Academic Search

Interleaved converters are an interesting alternative for many applications due to their advantage in terms of dynamic response, output ripple cancellation, EMI reduction, thermal management and optimized design. In this paper, the benefits of interleaving from the point of view of size and losses reduction of the passive components are quantified. An extensive study has been made considering actual components

J. A. Oliver; P. Zumel; O. Garcia; J. A. Cobos; J. Uceda

2004-01-01

18

Soft switched ac link buck boost converter  

Microsoft Academic Search

A novel soft switching high frequency link converter for medium and high power ac-ac and ac-dc applications is proposed. The proposed topology overcomes the shortcomings of conventional dc and ac link schemes and uses 12 bidirectional switches for a three phase to three phase configuration. An inductor-capacitor pair with low reactive rating forms the link. Switches turn on at zero

Anand Balakrishnan; Hamid A. Toliyat; William C. Alexander

2008-01-01

19

Buck-Boost Combined with Active Clamp Flyback Converter for PV Power System  

Microsoft Academic Search

This paper presents an LED lighting system with PV sources. The circuit of the proposed system adopts buck-boost converter associated with flyback converter to charge battery and to drive an LED lighting system. In this research, buck-boost converter is used as a charger for charging battery, and flyback converter with active clamp circuit is adopted to drive the LED lighting.

S.-Y. Tseng; J.-S. Kuo; S.-W. Wang; C.-T. Hsieh

2007-01-01

20

A new single switch Buck-Boost type dc-dc converter  

Microsoft Academic Search

In this paper a new single switch Buck-Boost type dc-dc converter is introduced. This converter consists of flyback and forward transformers and only one switch in primary side and one diode in secondary side of transformers. Also this converter operates in both buck and boost modes. In this converter energy transfers to the output in both on and off switch

M. Delshad; H. Farzanehfard

2009-01-01

21

Elimination of current spikes in buck power converters  

NASA Technical Reports Server (NTRS)

Current spikes in a buck power converter due to commutating diode turn-off time are eliminated by using a tapped inductor in the converter with the tap connected to the switching transistor. The commutating diode is not in the usual place, but is instead connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistor is not conducting. In the case of a converter having a center-tapped (primary and secondary) transformer between two switching power transistors operated in a push-pull mode and two rectifying diodes in the secondary circuit, current spikes due to transformer saturation are also eliminated by using a tapped inductor in the converter with the tap connected to the rectifying diodes and a diode connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistors are not conducting.

Mclyman, W. T. (inventor)

1981-01-01

22

An approach on TS fuzzy model and control of buck-boost converter  

Microsoft Academic Search

Considering the nonlinearity characteristic of buck-boost converter and combining with the fine part-linear characteristic of T-S fuzzy model, a novel T-S fuzzy model of buck-boost converter is proposed in this paper. Based on the constructed model, a parametrical design method of the buck-boost converter fuzzy controller is put forward via QLF method. And the parameters of controller can be obtained

Yuanlong Li; Zhicheng Ji

2008-01-01

23

Ratio buck-boost (RBB) converter with feed-forward technique for achieving fast line response  

Microsoft Academic Search

A ratio buck-boost (RBB) converter with feed-forward (FF) technique is proposed for regulating output voltage with fast line response. Owing to the ratio control technique, RBB converter can achieve high conversion efficiency due to only two turn-on switches within a switching period for all operation modes, which contains buck, boost, and buck-boost modes. Besides, feed-forward technique minimizes the voltage variations

Hsin-Hsin Ho; Pin-Chin Huang; Wei-Quan Wu; Ke-Horng Chen

2008-01-01

24

Analysis of buck converters for on-chip integration with a dual supply voltage microprocessor  

Microsoft Academic Search

An analysis of an on-chip buck converter is presented in this paper. A high switching frequency is the key design parameter that simulta- neously permits monolithic integration and high efficiency. A model of the parasitic impedances of a buck converter is developed. With this model, a design space is determined that allows integration of active and passive de- vices on

Volkan Kursun; Siva G. Narendra; Vivek K. De; Eby G. Friedman

2003-01-01

25

A Single-Phase Z-Source Buck–Boost Matrix Converter  

Microsoft Academic Search

This paper proposes a new type of converter called a single-phase Z-source buck-boost matrix converter. The converter can buck and boost with step-changed frequency, and both the frequency and the voltage can be stepped up or stepped down. In addition, the converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage

Minh-Khai Nguyen; Young-Gook Jung; Young-Cheol Lim; Young-Min Kim

2010-01-01

26

Nonlinear program based optimization of boost and buck-boost converter designs  

NASA Technical Reports Server (NTRS)

The facility of an Augmented Lagrangian (ALAG) multiplier based nonlinear programming technique is demonstrated for minimum-weight design optimizations of boost and buck-boost power converters. Certain important features of ALAG are presented in the framework of a comprehensive design example for buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight and loss profiles of various semiconductor components and magnetics as a function of the switching frequency.

Rahman, S.; Lee, F. C.

1981-01-01

27

Interleaved buck converter with variable number of active phases and a predictive current sharing scheme  

Microsoft Academic Search

The efficiency of an interleaved buck converter is typically low at light load conditions because of the switching losses in each of the switching stages. Improvements in the converter efficiency can be achieved by dynamically changing the number of active phases depending on the load current. This paper addresses the issues related to the transient response of the converter when

L. T. Jakobsen; O. Garcia; J. A. Oliver; P. Alou; J. A. Cobos; M. A. E. Andersen

2008-01-01

28

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

SciTech Connect

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.

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

29

Efficiency analysis of a high frequency buck converter for on–chip integration with a dual–VDDmicroprocessor  

Microsoft Academic Search

An analysis of the power characteristics of a buck converter is presented in this paper. A high switching frequency is the key design parameter that simultaneously permits monolithic integration and high efficiency. A parasitic model of the buck converter is developed. With this model, a design space is determined that allows integration of active and passive devices on the same

Volkan Kursun; Siva G. Narendra; Vivek K. De; Eby G. Friedman

2002-01-01

30

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

Microsoft Academic Search

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

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

2008-01-01

31

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

Microsoft Academic Search

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

Wuhua Li; Xiangning He

2008-01-01

32

Interleaved buck converters with a single-capacitor turn-off snubber  

Microsoft Academic Search

This paper proposes interleaved buck converters with a single-capacitor snubber to smooth out switch turn-off transition. The single-capacitor snubber is used to limit rising rate of drain-source voltage of the metal-oxide-semiconductor field-effect transistor (MOSFET) switch in the converters to reduce turn-off loss. In addition, the converters are operated at the boundary of continuous and discontinuous conduction modes (CCM), (DCM) to

Yaow-Ming Chen; Sheng-Yu Tseng; Cheng-Tao Tsai; Tsai-Fu Wu

2004-01-01

33

A new modulation strategy for a buck-boost input AC\\/DC converter  

Microsoft Academic Search

This paper presents a novel modulation strategy for a power factor corrected (PFC), isolated AC\\/DC converter derived from the integration of a nonisolated, two switch buck-boost AC\\/DC converter with an isolated dual active bridge DC\\/DC converter (2SBBDAB). This strategy, termed discontinuous leading\\/trailing edge (DLTE) modulation, serves to maximize the duty cycle of the input switch while keeping the current in

Richard Morrison; Michael G. Egan

2001-01-01

34

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

Microsoft Academic Search

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

Zhang Xiaofeng; Lu Zhengyu

2006-01-01

35

Model Predictive Control of buck DC-DC converter with nonlinear inductor  

Microsoft Academic Search

A model predictive control (MPC) approach that deals with the nonlinear behavior of the inductor in the buck DC-DC converter is presented. Based on a discrete approximation of a coil dynamics, a piecewise affine model that better represents the B-H characteristics is derived. For the fast execution of the MPC algorithm, a concept of explicit solutions to MPC is adopted.

S. Mariethoz; M. Herceg; M. Kvasnica

2008-01-01

36

Buck-Boost Converter for Sensorless Power Optimization of Piezoelectric Energy Harvester  

Microsoft Academic Search

This paper presents a comprehensive model for miniature vibration-powered piezoelectric generators and analyses modes of operation and control of a buck-boost converter for the purpose of tracking the generators optimal working points. The model describes the generator's power dependence with the mechanical acceleration and frequency, and helps in the definition of the load behaviour for power optimization. Electrical behaviour of

Elie Lefeuvre; David Audigier; Claude Richard; Daniel Guyomar

2007-01-01

37

Transfer function modeling and analysis of the open-loop Buck converter using the fractional calculus  

NASA Astrophysics Data System (ADS)

Based on the fact that the real inductor and the real capacitor are fractional order in nature and the fractional calculus, the transfer function modeling and analysis of the open-loop Buck converter in a continuous conduction mode (CCM) operation are carried out in this paper. The fractional order small signal model and the corresponding equivalent circuit of the open-loop Buck converter in a CCM operation are presented. The transfer functions from the input voltage to the output voltage, from the input voltage to the inductor current, from the duty cycle to the output voltage, from the duty cycle to the inductor current, and the output impedance of the open-loop Buck converter in CCM operation are derived, and their bode diagrams and step responses are calculated, respectively. It is found that all the derived fractional order transfer functions of the system are influenced by the fractional orders of the inductor and the capacitor. Finally, the realization of the fractional order inductor and the fractional order capacitor is designed, and the corresponding PSIM circuit simulation results of the open-loop Buck converter in CCM operation are given to confirm the correctness of the derivations and the theoretical analysis.

Wang, Fa-Qiang; Ma, Xi-Kui

2013-03-01

38

Magnetic near-field measurement for FDI of ZVS full bridge isolated buck converter  

Microsoft Academic Search

) Abstract -- This paper takes place within the more general framework of the faults detection and isolation for multi- sources renewable energy systems by aims of residuals synthesis and analysis. The main contribution is the use of a magnetic near-field measurement to estimate the magnetizing current of the HF transformer used in the ZVS full bridge isolated buck converters.

Francois Guerin; Cecile Labarre; Dimitri Lefebvre

2011-01-01

39

Analysis of buck-boost converter inductor loss using a simple online BH curve tracer  

Microsoft Academic Search

A simple method to plot online B-H curves and calculate the core loss of the inductor in a conventional buck-boost power converter is developed. In order to obtain a reliable loss data, measurement error and phase shift error are analyzed and then quantified. A new method to minimize measurement error is given. A new core loss model in terms of

H. Y. Chung; F. N. K. Poon; C. P. Liu; M. H. Pong

2000-01-01

40

Decoupled output voltage control of quantum series resonant converter for improved buck-boost operation  

Microsoft Academic Search

A new output voltage control technique is proposed to obtain the improved buck-boost operation of the quantum series resonant power converter (QSRC). The new nonlinear dynamic model of QSRC is first derived and the cross-coupled nonlinear term existing in the output voltage dynamics is decoupled by using control methods such as the periodic control of the boosting switch (PCBS) and

Byeong-Rim Jo; Hee-Wook Ahn; Gun-Woo Moon; Hyun-Chil Choi; Myung-Joong Youn

1996-01-01

41

Two-parameter chaotic control in the voltage controlled buck converter  

Microsoft Academic Search

This paper is concerned with the control of bifurcation and chaos in voltage controlled buck converter, which is a piecewise-smooth dynamical system. By taking the advantage of the OGY method, a two-parameter control strategy is put forward. It prevents the system from losing stability due to the error in obtaining the unstable periodic orbit (UPO) while OGY method is applied.

Zhu Ning; Wu Weilin

2003-01-01

42

A new control strategy to achieve sinusoidal line current in a cascade buck-boost converter  

Microsoft Academic Search

This work presents a detailed theoretical analysis and experimental results of a novel means of obtaining sinusoidal input current and unity power factor (UPF) via a cascade buck-boost power converter. Using the new configuration, sinusoidal line current in phase with the bus voltage is achieved, thanks to a new and simple to implement control strategy. Comparison between the input and

Mohamed C. Ghanem; Kamal Al-Haddad; Gilles Roy

1996-01-01

43

Soft switched ac-link AC\\/AC and AC\\/DC buck-boost converter  

Microsoft Academic Search

A novel soft switched AC-link buck-boost converter for medium and high power AC-AC and AC-DC applications is proposed. The proposed configuration uses two bi-directional switches per leg of the converter resulting in 12 bi-directional switches for a three-phase to three-phase topology. Power transfer from input to output is accomplished via a link inductor which is first charged from the input

Hamid A. Toliyat; Anand Balakrishnan; Mahshid Amirabadi; William Alexander

2008-01-01

44

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

Microsoft Academic Search

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

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

2007-01-01

45

Research on single-stage inverter based on bi-directional Buck DC converter  

Microsoft Academic Search

A novel type single-stage inverter is proposed in this paper. Details on operation principle, control strategy and circuit design of the new single-stage inverter are presented below. The single-stage inverter is constituted of two absolutely same bi-directional DC-DC Buck converters which get high frequency electrical isolation. The converters' input and output are individually in parallel and in series. Then a

Ma Yundong; Qiu Bin; Cong Qing

2010-01-01

46

H? integral control of a buck-boost dc-dc converter  

Microsoft Academic Search

In this paper Hinfin integral control is used to improve the performance of a buck-boost dc-dc power converter based on pulse-width modulation (PWM) techniques. The converter is used to supply a robust, stable negative voltage source to the electrical and electronic systems of next-generation cars, which will have to perform not only under 42 V technology, but also with many

Wilmar Hernandez

2008-01-01

47

A new isolated bidirectional buck-boost PWM converter  

Microsoft Academic Search

In this paper, a new isolated dc-dc bidirectional converter is introduced. This converter consists of flyback and forward transformers and only one switch in primary side and one switch in secondary side of transformers. In this converter energy transfers to the output in both on and off switch states and controlled by PWM signal. Therefore implementation of control circuits is

M. Delshad; H. Farzanehfard

2010-01-01

48

A New Approach for High Efficiency Buck-Boost DC/DC Converters Using Series Compensation  

NASA Astrophysics Data System (ADS)

This paper proposes a novel concept for non-isolated buck-boost DC/DC converter and control method. The proposed concept uses a series connection converter that only regulates the differential voltage between the input and output voltage. As a result, the power converter capacity is decreased. Moreover, the proposed circuit has advantages such as improved efficiency and losses reduction. The fundamental operation, control method, and design method of the proposed circuit are described in this paper. In addition, the validity of the proposed circuit is confirmed by carrying out simulations and experiments.

Itoh, Jun-Ichi; Fujii, Takashi

49

A current-mode DC—DC buck converter with adaptive zero compensation  

NASA Astrophysics Data System (ADS)

To achieve fast transient response for a DC—DC buck converter, an adaptive zero compensation circuit is presented. The compensation resistance is dynamically adjusted according to the different output load conditions, and achieves an adequate system phase margin under the different conditions. An improved capacitor multiplier circuit is adopted to realize the minimized compensation capacitance size. In addition, analysis of the small-signal model shows the correctness of the mechanism of the proposed adaptive zero compensation technique. A current-mode DC—DC buck converter with the proposed structure has been implemented in a 0.35 ?m CMOS process, and the die size is only 800 × 1040 ?m2. The experimental results show that the transient undershoot/overshoot voltage and the recovery times do not exceed 40 mV and 30 ?s for a load current variation from 100 mA to 1 A.

Ling, Yang; Guoding, Dai; Chongwei, Xu; Yuezhi, Liu

2013-08-01

50

Optimal design of interleaved synchronous buck converter at high slew-rate load current transients  

Microsoft Academic Search

An interleaved synchronous-buck converter for powering future microprocessors is analyzed at high slew-rate load-current transients. Optimal design procedure is suggested based on derived equations for any number of channels. Output filter design example for popular 12-V input, 1.5-V, 50-A regulator is presented to illustrate analysis and compare different number of channels and type of capacitors for this application

Rais Miftakhutdinov

2001-01-01

51

PI controller design via singular perturbation technique for AC-AC buck-boost converter  

Microsoft Academic Search

The problem of AC voltage regulation based on AC-AC buck-boost converter is discussed in presence of resistor load variations and voltage source variations as well. The design methodology of cascaded proportional-integral (PI) controller via singular perturbation technique is presented where two-time-scale motions are artificially induced in the closed-loop system. Stability conditions imposed on the fast and slow modes and sufficiently

V. D. Yurkevich; G. S. Zinoviev

2008-01-01

52

Design of closed-loop buck-boost converter for LED driver circuit  

Microsoft Academic Search

This paper develops a light emitting diode (LED) driver circuit with a buck-boost converter. The forward bias of the LED used was 3.1V~4.3V, and the forward current was 0.7A. Twelve 3W white-light LEDs were driven in series in the proposed circuit. Each LED was operated at 4V and 0.6A using ac 110V that was rectified by a bridge rectifier. It

Chi-Jen Huang; Ying-Chun Chuang; Yu-Lung Ke

2011-01-01

53

Sampled-data modeling of the average-input current-mode-controlled buck converter  

Microsoft Academic Search

Average-input current-mode control (AICMC) is a new control scheme for shaping the input current of a buck converter in a high-power-factor rectifier. AICMC is presented along with a continuous-time model that includes sampled-data effects. AICMC is found to be analogous to current mode control (CMC), so existing CMC models are reviewed with regard to the controversies over low-frequency modulator gain

Yen-Wu Lo; R. J. King

1999-01-01

54

Time optimal, parameters-insensitive digital controller for DC-DC buck converters  

Microsoft Academic Search

In this paper a digital control approach is investigated for time-optimal load step response of DC-DC synchronous buck converters intended for point-of-load applications employing low-ESR ceramic output capacitors. Unlike previously reported approaches, the proposed technique is insensitive to the power stage parameters, as its operation does not rely on the knowledge of the output filter inductance or capacitance. The time-optimal

A. Costabeber; L. Corradini; P. Mattavelli; S. Saggini

2008-01-01

55

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

Microsoft Academic Search

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

Rae-Young Kim; Jih-Sheng Lai

2008-01-01

56

Open-loop dc and small-signal characteristics of PWM buck-boost converter for CCM  

Microsoft Academic Search

This paper introduces dc and small-signal circuit models for the PWM buck-boost converter that take into account parasitic components, such as the ESR of the fitter capacitor, the ESR of the inductor, the transistor on-resistance, and the diode forward resistance and offset voltage. Dc and small-signal circuit models for the buck-boost converter are introduced. The dc voltage transfer function and

Marian K. Kazimierczuk; Robert Cravens

1994-01-01

57

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

58

Modeling and dynamics analysis of the fractional-order Buck—Boost converter in continuous conduction mode  

NASA Astrophysics Data System (ADS)

In this paper, the fractional-order mathematical model and the fractional-order state-space averaging model of the Buck—Boost converter in continuous conduction mode (CCM) are established based on the fractional calculus and the Adomian decomposition method. Some dynamical properties of the current-mode controlled fractional-order Buck—Boost converter are analysed. The simulation is accomplished by using SIMULINK. Numerical simulations are presented to verify the analytical results and we find that bifurcation points will be moved backward as ? and ? vary. At the same time, the simulation results show that the converter goes through different routes to chaos.

Yang, Ning-Ning; Liu, Chong-Xin; Wu, Chao-Jun

2012-08-01

59

A 10 MHz ripple-based on-time controlled buck converter with dual ripple compensation  

NASA Astrophysics Data System (ADS)

A 10 MHz ripple-based on-time controlled buck converter is presented. A novel low-cost dual ripple compensation, which consists of coupling capacitor compensation and passive equivalent series resistance compensation, is proposed to achieve a fast load transient response and robust stability simultaneously. Implemented in a 2P4M 0.35 ?m CMOS process, the converter achieves fix-frequency output with a ripple of below 10 mV and an overshoot of 10 mV at 400 mA step load transient response. With width optimization of the power transistors in an ultra-heavy load and PFM control in a light load, the efficiency stays at over 83% for a load range from 20 mA to 1.5 A and the peak efficiency reaches 90.16%.

Danzhu, Lü; Jiale, Yu; Zhiliang, Hong

2013-02-01

60

Low-temperature operation of a Buck DC/DC converter  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

61

Bidirectional buck\\/boost dc-dc converter with ultra high efficiency based on improved SAZZ topology  

Microsoft Academic Search

An improved bi-directional buck\\/boost SAZZ topology is proposed in this paper. The improvements are aimed at increasing the total conversion efficiency as well as at enlarging the soft switching operating area and hence improving the overall converter performance. The modifications with respect to the conventional SAZZ topology are: configuration of snubber circuits enhanced by saturable inductors and use of synchronous

M. Pavlovsky; Y. Tsuruta; A. Kawamura

2009-01-01

62

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

Microsoft Academic Search

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

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

2007-01-01

63

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

PubMed Central

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.

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

2014-01-01

64

An optimal current observer for predictive current controlled buck DC-DC converters.  

PubMed

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

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

2014-01-01

65

A Multistage Interleaved Synchronous Buck Converter With Integrated Output Filter in 0.18 ?m SiGe Process  

Microsoft Academic Search

The design and analysis of a fully integrated multistage interleaved synchronous buck dc-dc converter with on-chip filter inductor and capacitor is presented. The dc-dc converter is designed and fabricated in 0.18 mum SiGe RF BiCMOS process technology and generates 1.5 V-2.0 V programmable output voltage supporting a maximum output current of 200 mA. High switching frequency of 45 MHz, multiphase

Siamak Abedinpour; Bertan Bakkaloglu; Sayfe Kiaei

2007-01-01

66

Identifier-based adaptive neural dynamic surface control for uncertain DC-DC buck converter system with input constraint  

NASA Astrophysics Data System (ADS)

In this paper, an identifier-based adaptive neural dynamic surface control (IANDSC) is proposed for the uncertain DC-DC buck converter system with input constraint. Based on the analysis of the effect of input constraint in the buck converter, the neural network compensator is employed to ensure the controller output within the permissible range. Subsequently, the constrained adaptive control scheme combined with the neural network compensator is developed for the buck converter with uncertain load current. In this scheme, a newly presented finite-time identifier is utilized to accelerate the parameter tuning process and to heighten the accuracy of parameter estimation. By utilizing the adaptive dynamic surface control (ADSC) technique, the problem of "explosion of complexity" inherently in the traditional adaptive backstepping design can be overcome. The proposed control law can guarantee the uniformly ultimate boundedness of all signals in the closed-loop system via Lyapunov synthesis. Numerical simulations are provided to illustrate the effectiveness of the proposed control method.

Chen, Qiang; Ren, Xuemei; Oliver, Jesus Angel

2012-04-01

67

A 65MHZ switching rate, two-stage interleaved synchronous buck converter with fully integrated output filter  

Microsoft Academic Search

Design and analysis of a fully integrated two-stage interleaved synchronous buck DC-DC converter with on-chip filter inductor and capacitor is presented. The DC-DC converter is designed and fabricated in a 0.18 mum SiGe RFBiCMOS process technology and generates 1.5V-2.0V programmable output voltage supporting a maximum output current of 200mA. High switching frequency, multi-phase interleaved operation, and fast hysteretic controller reduce

S. Abedinpour; B. Bakkaloglu; S. Kiaei

2006-01-01

68

Combination of Buck and Boost Modes to Minimize Transients in the Output of a Positive Buck-Boost Converter  

Microsoft Academic Search

This paper describes a new method for minimizing the transients in the output of a DC-DC converter required for small powered portable electronic applications. The transient problem has been the most serious problem for power supplies needing the output voltage in the mid-range of the input voltage. The maximum transient arises when the input voltage becomes almost equal to the

A. Chakraborty; A. Khaligh; A. Emadi

2006-01-01

69

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

70

Design of a bidirectional buck-boost dc\\/dc converter for a series hybrid electric vehicle using PSCAD\\/EMTDC  

Microsoft Academic Search

A process for the design and development of a bidirectional buck-boost dc\\/dc converter for use as a generator controller in a series hybrid electric vehicle is presented. The converter allows a single permanent magnet dc (PMDC) electric machine to be used for both engine starting and generating modes. The power electronics and the control system methodology are studied and refined

D. R. Northcott; S. Filizadeh; A. R. Chevrefils

2009-01-01

71

Digital control methods for current sharing of interleaved synchronous buck converter  

Microsoft Academic Search

The quasi square wave operation of the synchronous buck with interleaved parallel outputs has been successfully used in low voltage high current DC-supply for microprocessors. This topology results in fast transient response and high power density. In this paper, two digital control strategies for current sharing control are tested by simulation in Simulink, and tested in the laboratory. The digital

P. Andreassen; T. M. Undeland

2005-01-01

72

A fast novel soft-start circuit for peak current-mode DC—DC buck converters  

NASA Astrophysics Data System (ADS)

A fully integrated soft-start circuit for DC—DC buck converters is presented. The proposed high speed soft-start circuit is made of two sections: an overshoot suppression circuit and an inrush current suppression circuit. The overshoot suppression circuit is presented to control the input of the error amplifier to make output voltage limit increase in steps without using an external capacitor. A variable clock signal is adopted in the inrush current suppression circuit to increase the duty cycle of the system and suppress the inrush current. The DC—DC converter with the proposed soft-start circuit has been fabricated with a standard 0.13 ?m CMOS process. Experimental results show that the proposed high speed soft-start circuit has achieved less than 50 ?s start-up time. The inductor current and the output voltage increase smoothly over the whole load range.

Jie, Li; Miao, Yang; Weifeng, Sun; Xiaoxia, Lu; Shen, Xu; Shengli, Lu

2013-02-01

73

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

SciTech Connect

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.

Onar, Omer C [ORNL

2012-01-01

74

Study of the Effect and Design Criteria of the Input Filter for Buck Converters With Peak Current-Mode Control Using a Novel System Block Diagram  

Microsoft Academic Search

The effect and design criteria of the input filter for buck converters with peak current-mode (PCM) control are researched using a novel system block diagram. With this diagram, a novel current loop transfer function is proposed to derive the design criteria that apply to designing the input filter. However, the input filter that is added to reduce electromagnetic interference will

Shen-Yaur Chen; Jin-Jia Chen

2008-01-01

75

Study on the dynamic performance of a novel buck-boost matrix converter based on double-loop control strategy  

NASA Astrophysics Data System (ADS)

The dynamic performance of a novel Buck-Boost matrix converter (BBMC) based on double-loop control strategy is put forward in this paper. The fundamental principle of BBMC has been elaborated and the method of the double-loop control strategy has been built with Matlab, and then the dynamic performances of BBMC based on the double-loop control strategy are discussed. The results show that the output voltage and frequency can be almost constant with the BBMC and double-loop control strategy despite of the changeable input voltage and frequency. Moreover, a high-quality sine output wave with low harmonic distortion can be directly obtained without filtering. So it can be drawn that the BBMC based on the double-loop control strategy has perfectly dynamic performance and practical importance to the engineering.

Li, Qing; Zhang, Xiao-Ping; Chen, Qi

2011-08-01

76

Two-phase buck-boost type 100 kW DC-DC converter developed for the electric railway rolling stock  

Microsoft Academic Search

A two-phase buck-boost-type high-voltage\\/high-current DC-DC converter is proposed, for application to an auxiliary power source in electric railway rolling stock. The main load of the converter is a three-phase inverter which supplies AC power to an inverter-type air-conditioner, by experiments. The circuit behavior and the operation modes are examined, and the steady-state and dynamic characteristics are analyzed using the averaged

Katsuji Iida; T. Kishmoto; Hirofurni Matsuo; F. Furokawa; Mutsuyoshi Asano

1992-01-01

77

A MultiStage Interleaved Synchronous Buck Converter with Integrated Output Filter in a 0.18\\/spl mu\\/ SiGe process  

Microsoft Academic Search

A fully integrated 0.18mum SiGe synchronous buck DC\\/DC converter with an on-chip LC output filter supporting a maximum output current of 200mA and efficiency of 64% is presented. The converter utilizes a 10mum-thick electroplated copper layer for integrated inductors and gate capacitors. High switching frequency of 45MHz, multi-phase interleaved operation, and fast hysteretic control reduces the filter inductor and capacitor

Siamak Abedinpour; Bertan Bakkaloglu; Sayfe Kiaei

2006-01-01

78

High efficiency Single-Inductor Boost\\/Buck Inverting Flyback converter with hybrid energy transfer media and multi level gate driving for AM OLED panel  

Microsoft Academic Search

A hybrid-type Single Inductor Boost\\/Buck Inverting Flyback(SIBBIF) DC-DC Converter is presented. To increase the converter efficiency, a flying capacitor as well as an inductor is adopted as another energy transfer medium together with multi-level gate driver (MLGD). Besides, to enhance load transient response, hybrid fast transient control (HFTC) is adopted. The proposed chip is implemented in a 0.5-?m power BCD

Se-Won Wang; Young-Jin Woo; Young-Sub Yuk; Gyu-Hyeong Cho; Gyu-Ha Cho

2010-01-01

79

A new zero voltage switching buck-boost bidirectional DC_DC converter  

Microsoft Academic Search

In this paper a new zero voltage switching bidirectional dc-dc converter is introduced. This converter consists of flyback and forward transformers and only one main switch in primary side and one main switch in secondary side of transformers. Auxiliary circuits in this converter consist of a switch and one clamp capacitor. These circuits not only absorb spikes across the switches

Majid Delshad; M. Mahdavi

2010-01-01

80

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

NASA Astrophysics Data System (ADS)

This paper presents a width controller, a dead time controller, a discontinuous current mode (DCM) controller and a frequency skipping modulation (FSM) controller for a high frequency high efficiency buck DC-DC converter. To improve the efficiency over a wide load range, especially at high switching frequency, the dead time controller and width controller are applied to enhance the high load efficiency, while the DCM controller and FSM controller are proposed to increase the light load efficiency. The proposed DC-DC converter controllers have been designed and fabricated in the Chartered 0.35 ?m CMOS process, and the measured results show that the efficiency of the buck DC-DC converter is above 80% over a wide load current range from 8 to 570 mA, and the peak efficiency is 86% at 10 MHz switching frequency.

Changming, Pi; Wei, Yan; Ke, Zhang; Wenhong, Li

2010-08-01

81

Single-Switch Equalization Charger Using Multiple Stacked Buck-Boost Converters for Series-Connected Energy-Storage Modules  

NASA Astrophysics Data System (ADS)

Series connections of energy-storage modules such as electric double-layer capacitors (EDLCs) and lithium-ion batteries result in voltage imbalance because of the nonuniform properties of individual modules. Conventional voltage equalizers based on traditional dc-dc converters require numerous switches and/or transformers, and therefore, their costs and complexity tend to increase. This paper proposes a novel single-switch equalization charger using multiple stacked buck-boost converters. The single-switch operation not only reduces the circuit complexity but also contributes to increasing the reliability. The fundamental operating principles and design procedures of key components are presented in detail. An experimental charge test using a 25W prototype of the proposed equalization charger was performed for four series-connected EDLC modules whose initial voltages were intentionally imbalanced. Experimental results demonstrated that the proposed equalization charger could charge the series-connected modules preferentially in the order of increasing module voltage and that all the modules could be charged up to a uniform voltage level.

Uno, Masatoshi; Tanaka, Koji

82

A 1500 mA, 10 MHz on-time controlled buck converter with ripple compensation and efficiency optimization  

NASA Astrophysics Data System (ADS)

A 1500 mA, 10 MHz self-adaptive on-time (SOT) controlled buck DC—DC converter is presented. Both a low-cost ripple compensation scheme (RCS) and a self-adaptive on-time generator (SAOTG) are proposed to solve the system stability and frequency variation problem. Meanwhile a self-adaptive power transistor sizing (SAPTS) technique is used to optimize the efficiency especially with a heavy load. The circuit is implemented in a 2P4M 0.35 ?m CMOS process. A small external inductor of 0.47 ?H and a capacitor of 4.7 ?F are used to lower the cost of the converter and keep the output ripple to less than 10 mV. The measurement results show that the overshoot of the load transient response is 8 mV @ 200 mA step and the dynamic voltage scaling (DVS) performance is a rise of 16 ?s/V and a fall of 20 ?s/V. With a SAPTS technique and PFM control, the efficiency is maintained at more than 81% for a load range of 20 to 1500 mA and the peak efficiency reaches 88.43%.

Jiale, Yu; Danzhu, Lü; Zhiliang, Hong

2012-01-01

83

A Monolithic Current-Mode Buck Converter With Advanced Control and Protection Circuits  

Microsoft Academic Search

A monolithic current-mode pulse width modulation (PWM) step-down dc-dc converter with 96.7% peak efficiency and advanced control and protection circuits is presented in this paper. The high efficiency is achieved by \\

Feng-Fei Ma; Wei-Zen Chen; Jiin-Chuan Wu

2007-01-01

84

Two-phase interleaved buck converter with a new Digital Self-Oscillating Modulator  

Microsoft Academic Search

This paper presents a new digital self-oscillating modulator (DiSOM) for DC\\/DC converters. The DiSOM modulator allows the digital control algorithm to sample the output voltage at a sampling frequency higher than the converter switching frequency. This enables higher control loop bandwidth than for traditional digital PWM modulators given a certain switching frequency. A synchronised version of the DiSOM modulator is

Lars T. Jakobsen; Michael A. E. Andersen

2007-01-01

85

Single-switch constant-power equalization charger based on multi-stacked buck-boost converters for series-connected supercapacitors in satellite power systems  

Microsoft Academic Search

Supercapacitors (SCs) have potential to be good alternatives to batteries in satellite power systems because they not only have a longer life but also reduce the mass of photovoltaic arrays when they are charged using a constant-power (CP) charging scheme. In this paper, we propose singles-witch CP equalization chargers using multi-stacked buck-boost converters. In addition to the single-switch operations, the

Masatoshi Uno; Koji Tanaka

2011-01-01

86

Voltage regulator module with interleaved synchronous buck converters and novel voltage-mode hysteretic control  

Microsoft Academic Search

Today's on-board low-voltage, high-current DC-DC voltage regulator module (VRM) requirements for the new generation of ICs and microprocessors are increasingly becoming stricter than ever, as the demand for high dynamic performance and high power density converters continues to increase. A new scheme that combines an interleaved technique and voltage-mode hysteretic control approach, by upgrading an existing single-phase chip, is proposed.

Jaber A. Abu Qahouq; Jia Luo; Issa Batarseh

2001-01-01

87

Input filter interactions in peak-current-mode-controlled buck converter operating in CICM  

Microsoft Academic Search

Peak-current-mode (PCM) control is a widely used method to control switched-mode converters. Most often an input filter is necessary to meet electromagnetic interference requirements. The input filter can cause instability and degradation of input and output dynamics if not properly designed. The input filter design from the output dynamics viewpoint has been addressed in numerous papers, resulting in well-agreed results

Teuvo Suntio; Idris Gadoura; Kai Zenger

2002-01-01

88

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

89

A Current-Mode DC–DC Buck Converter with Efficiency-Optimized Frequency Control and Reconfigurable Compensation  

Microsoft Academic Search

Large input voltage range and wide output current range are usually needed for dc–dc converters. For these input and output conditions, the converter's efficiency can be maximized by a proposed method, efficiency-optimized switching-frequency (EOF) control. The optimal switching frequency for maximizing the efficiency is generated by the low-complexity and low-power EOF generator. A reconfigurable compensator is developed for improving the

Jia-Ming Liu; Pai-Yi Wang; Tai-Haur Kuo

2012-01-01

90

Study of bi-directional buck-boost converter topologies for application in electrical vehicle motor drives  

Microsoft Academic Search

The use of a bi-directional DC-DC converter in motor drives devoted to EVs allows a suitable control of both motoring and regenerative braking operations. In particular, during motoring operations of a battery-fed DC motor drive, a DC-DC converter is to be used to adjust the motor current in order to follow the torque reference signal. On the other hand, a

F. Caricchi; F. Crescimbini; F. G. Capponi; L. Solero

1998-01-01

91

Small-signal AC modeling technique of Buck converter with DSP based Proportional-Integral-Derivative (PID) controller  

Microsoft Academic Search

Control applications of switched mode power supplies have been widely explored. The main objective of research and development (R&D) in this field has always been to find the simplest method to analyze and model the DC\\/DC converter and the most suitable control method to be implemented in various DC\\/DC converter topologies. This paper presents a simple and systematic approach to

M. F. N. Tajuddin; N. A. Rahim

2009-01-01

92

New Zero Current Transition PWM Converters  

Microsoft Academic Search

In this paper a new auxiliary circuit is introduced for applying to buck, buck-boost, forward and flyback converters. This auxiliary circuit provides zero current switching condition for all switching elements. The proposed ZCT PWM buck converter is analyzed and various operating modes are presented. Design considerations are explained and a design example along with experimental results of ZCT buck converter

E. Adib; H. Farzaneh-fard

2006-01-01

93

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

Microsoft Academic Search

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

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

2010-01-01

94

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

Microsoft Academic Search

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

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

2003-01-01

95

Modeling PWM DC\\/DC converters out of basic converter units  

Microsoft Academic Search

An alternative approach to modeling pulsewidth-modulated (PWM) DC\\/DC converters out of basic converter units (BCUs) is presented in this paper. Typical PWM DC\\/DC converters include the well-known buck, boost, buck-boost, Cuk, Zeta, and Sepic. With proper reconfiguration, these converters can be represented in terms of either buck or boost converter and linear devices, thus, the buck and boost converters are

Tasi-Fu Wu; Yu-Kai Chen

1998-01-01

96

New Zero Voltage Transition PWM Converters  

Microsoft Academic Search

In this paper a new auxiliary circuit is introduced for buck, buck-boost, forward and flyback converters. This auxiliary circuit provides zero voltage switching condition for the main switch and diode while providing zero current switching condition for the auxiliary switch and diodes. The proposed ZVT PWM buck converter is analyzed and various converter operating modes are presented. A very simple

E. Adib; H. Farzaneh-fard

2006-01-01

97

Log Bucking and Lumber Manufacturing Using Dynamic Programming  

Microsoft Academic Search

The process of converting a tree into finished lumber involves several interrelated steps. The two of greatest potential for improvement are cutting the felled tree into shorter logs (called bucking the tree) and sawing the bucked logs into lumber. Unlike previous work in the area, this paper considers the two activities together as a single production system. The model allows

Bruce Faaland; David Briggs

1984-01-01

98

Buck-boost DC-AC inverter: proposal for a new control strategy  

Microsoft Academic Search

The buck-boost DC-AC inverter is a special topology consisting of two buck-boost DC-DC converters that generate an AC output voltage in a single stage. This is achieved by means of driving both buck-boost DC-DC converters with two 180° phase-shifted DC-biased sinusoidal references. The differential output voltage is therefore an AC output voltage whose peak value is independent of the DC

P. Sanchis; A. Ursua; E. Gubia; L. Marroyo

2004-01-01

99

Control and Stabilization of DC\\/DC Buck-Boost Converters Loaded by Constant Power Loads in Vehicular Systems using a Novel Digital Scheme  

Microsoft Academic Search

Power electronics based power systems are being increasingly considered for transportation systems such as land, sea\\/undersea, air, and space vehicles due to their advantages in efficiency, performance, flexibility, and power density. In order to have superior performance, these multi-converter systems need to be rigorously regulated. Dynamic response of tightly regulated power electronic converters in distributed power electronic systems is similar

Alireza Khaligh; Sheldon S. Williamson; Ali Emadi

2006-01-01

100

Four quadrant operating Luo-converters  

Microsoft Academic Search

Classical DC-DC converters usually perform in single quadrant operation, such as buck converter, boost converter, buck-boost converter, Cuk-converter and Luo-converters. In industrial applications four-quadrant operation is required, e.g. a DC motor runs forward and reverse in motoring and regenerative braking states. This paper introduces a new converter that can perform four-quadrant DC\\/DC conversion. Because this converter implements dual-direction energy transference

Fang L. Luo; Hong Ye; Muhammad H. Rashid

2000-01-01

101

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

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

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

2009-01-01

102

Switched-capacitor DC-DC converters  

Microsoft Academic Search

Novel switched-capacitor (SC) DC-DC converters are derived from three basic SC DC-DC converters. The converter outputs can be regulated by changing the duty ratio of the transistor switch. These converters have features not found in conventional switching regulators (buck, boost, and buck-boost converters). Of these converters, the voltage polarity inverting converter is expected to be widely used for small-size, small-power

K. Kuwabara; E. Hiyachika

1988-01-01

103

Converter  

NSDL National Science Digital Library

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.

2010-01-01

104

Buck-boost impedance networks  

Microsoft Academic Search

Most inverters designed to date can only perform either voltage-buck or boost operation with buck-boost mode usually attained by introducing additional active semiconductor devices and passive components to the inverters. Although effective, adding active switches will complicate the inverter control, and push up the overall system costs. Therefore, alternative topological solutions are of interest, and should preferably be implemented using

Poh Chiang Loh; Feng Gao; Frede Blaabjerg; Ai Lian Goh

2007-01-01

105

Family of Zero-Current Transition PWM Converters  

Microsoft Academic Search

In this paper, a new auxiliary circuit is introduced for applying to buck, buck-boost, zeta, forward, and flyback converters. This auxiliary circuit provides a zero-current switching condition for all switching elements. The proposed zero-current transition (ZCT) pulsewidth-modulated buck converter is briefly described. Also, a ZCT flyback converter is analyzed, and its different operating modes are presented. Design considerations are explained,

Ehsan Adib; Hosein Farzanehfard

2008-01-01

106

Multifunctional interleaved boost converter for PV systems  

Microsoft Academic Search

In this study, an interleaved boost converter cascaded with a battery charger buck converter is designed and implemented. The converter also has maximum power point tracking capability and the battery charge operation is designed for purpose of long life requirements of batteries. Proposed interleaved boost converter operates in conventional converter mode and in interleaved boost converter mode with different switching

I. Sefa; S. O?zdemir

2010-01-01

107

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.

2009-11-06

108

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.

109

A systematic approach to developing single-stage soft switching PWM converters  

Microsoft Academic Search

A systematic approach to developing soft switching PWM converters based on the synchronous switch scheme is presented in this paper. With the approach, several families of passive and active soft switching PWM converters, such as buck-boost, Zeta, Cuk, and Sepic, can be generated from the two basic converters, buck and boost. Also, the approach is used to integrate multiple converters

Tsai-Fu Wu; Shih-An Liang

2001-01-01

110

Control of three-phase single-stage isolated buck+boost unity power factor rectifier for unbalanced input voltages  

Microsoft Academic Search

A single-stage structure is proposed for realizing a unity power factor three-phase isolated AC-DC converter for telecommunication power supply modules. This structure is composed by integrating a boost converter to the isolated three-phase three-switch buck rectifier. Modified space vector modulation method is applied to the three-phase three-switch isolated unity power factor input buck rectifier based on the space vector modulation

Ali Mohammadpour; Mohammad Reza Zolghadri

2009-01-01

111

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

Microsoft Academic Search

This paper discusses the use of PCB integrated inductors for low power DC\\/DC buck converters. Coreless, magnetic plates and closed core structures are compared in terms of achievable inductance, power handling and efficiency in a footprint of 10 × 10 mm2. Analytic and FEM methods are applied and typical current waveforms encountered in a buck converter are included. The magnetic

Matthias Ludwig; Maeve Duffy; Terence Ó Donnell; Cian Ó Mathuna

2002-01-01

112

Power quality improvement in telecommunication power supply system using buck rectifier  

Microsoft Academic Search

The rampant use of telecommunication power supplies cause huge harmonic distortion and low power factor at the utility interface. These have to be curtailed so that the cost of the converter and filter components can be brought down. In this paper, a buck converter is used for ac-dc conversion in the proposed telecommunication power supply that takes care of power

Shikha Singh; G. Bhuvaneswari; Bhim Singh

2011-01-01

113

Some criteria of topology selection for hybrid converters  

Microsoft Academic Search

A new concept of telecommunications exchange, based on the distributed power supply idea is discussed. This concept brings a considerable increase of telecommunications exchange reliability. An analysis of thick film hybrid technology for realization of DC\\/DC converters is presented. Buck and boost converters, flyback converters, forward converters, push-pull converters, and Cuk converters are discussed

S. Radosevic; M. Lazic; R. Ramovic

1997-01-01

114

Bucking Trends: Expanding the Arts  

ERIC Educational Resources Information Center

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…

Levin, Kathi R.

2008-01-01

115

Conference James F.Buckli  

SciTech Connect

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

None

2008-02-07

116

Conference James F.Buckli  

ScienceCinema

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

None

2011-04-25

117

Series-Connected Buck Boost Regulators  

NASA Technical Reports Server (NTRS)

A series-connected buck boost regulator (SCBBR) is an electronic circuit that bucks a power-supply voltage to a lower regulated value or boosts it to a higher regulated value. The concept of the SCBBR is a generalization of the concept of the SCBR, which was reported in "Series-Connected Boost Regulators" (LEW-15918), NASA Tech Briefs, Vol. 23, No. 7 (July 1997), page 42. Relative to prior DC-voltage-regulator concepts, the SCBBR concept can yield significant reductions in weight and increases in power-conversion efficiency in many applications in which input/output voltage ratios are relatively small and isolation is not required, as solar-array regulation or battery charging with DC-bus regulation. Usually, a DC voltage regulator is designed to include a DC-to-DC converter to reduce its power loss, size, and weight. Advances in components, increases in operating frequencies, and improved circuit topologies have led to continual increases in efficiency and/or decreases in the sizes and weights of DC voltage regulators. The primary source of inefficiency in the DC-to-DC converter portion of a voltage regulator is the conduction loss and, especially at high frequencies, the switching loss. Although improved components and topology can reduce the switching loss, the reduction is limited by the fact that the converter generally switches all the power being regulated. Like the SCBR concept, the SCBBR concept involves a circuit configuration in which only a fraction of the power is switched, so that the switching loss is reduced by an amount that is largely independent of the specific components and circuit topology used. In an SCBBR, the amount of power switched by the DC-to-DC converter is only the amount needed to make up the difference between the input and output bus voltage. The remaining majority of the power passes through the converter without being switched. The weight and power loss of a DC-to-DC converter are determined primarily by the amount of power processed. In the SCBBR, the unswitched majority of the power is passed through with very little power loss, and little if any increase in the sizes of the converter components is needed to enable the components to handle the unswitched power. As a result, the power-conversion efficiency of the regulator can be very high, as shown in the example of Figure 1. A basic SCBBR includes a DC-to-DC converter (see Figure 2). The switches and primary winding of a transformer in the converter is connected across the input bus, while the secondary winding and switches are connected in series with the output bus, so that the output voltage is the sum of the input voltage and the secondary voltage of the converter. In the breadboard SCBBR, the input voltage applied to the primary winding is switched by use of metal oxide/semiconductor field-effect transistors (MOSFETs) in a full bridge circuit; the secondary winding is center-tapped, with two MOSFET switches and diode rectifiers connected in opposed series in each leg. The sets of opposed switches and rectifiers are what enable operation in either a boost or a buck mode. In the boost mode, input voltage and current, and the output voltage and current are all positive; that is, the secondary voltage is added to the input voltage and the net output voltage can be regulated at a value equal or greater than the input voltage. In the buck mode, input voltage is still positive and the current still flows in the same direction in the secondary, but the switches are controlled such that some power flows from the secondary to the primary. The voltage across the secondary and the current into the primary are reversed. The result is that the output voltage is lower than the input voltage, and some power is recirculated from the converter secondary back to the input. Quantitatively, the advantage of an SCBBR is a direct function of the regulation range required. If, for example, a regulation range of 20 percent is required for a 500-W supply, th it suffices to design the DC-to-DC converter in the SCBBR for a power rating of only 1

Birchenough, Arthur G.

2005-01-01

118

Application of neural network based model predictive controller to power switching converters  

Microsoft Academic Search

Neural network based Model Predictive Controller (MPC) for a dc-dc buck converter working in Continuous Conduction Mode (CCM) is presented. The converter operates at a switching frequency of 500 KHz. Although neural networks (NN) have been used in problems involving knotty, non-linearity and uncertainties but here they are applied to a buck converter to control its characteristics. The neural network

Ghulam Abbas; Umar Farooq; Muhammad Usman Asad

2011-01-01

119

Monolithic DC-DC Converter Analysis And Mosfet Gate Voltage Optimization  

Microsoft Academic Search

The design of an efficient monolithic buck converter is presented in this paper. A low swing MOSFET gate drive technique is proposed that improves the efficiency characteristics of a DC-DC converter. A model of the parasitic impedances of a buck converter is developed. With this model, a design space is described which characterizes the integration of both active and passive

Volkan Kursun; Siva Narendra; Vivek De; Eby G. Friedman

2003-01-01

120

Buck/boost regulator  

NASA Technical Reports Server (NTRS)

A voltage regulated DC to DC converter uses an inductor and a capacitor as storage elements. The inductor is composed of two windings having a common junction. A transformer with a center tap connected to the common junction of the two windings is connected at either end of its winding to ground through controlled switches. One winding of the inductor and either end of the transformer winding are connected by power diodes to the capacitor which supplies the output voltage to a load. The other winding of the inductor is connected to a fourth power diode as a clamping diode. Input voltage is supplied to the inductor through a third controlled switch. A pulse width modulator connected to the output of the converter alternately closes and opens the switches connected to either end of the transformer winding and also closes the switch supplying input voltage to the inductor each time either of the switches connected to the ends of the transformer winding are closed. The duty cycle of the closing and opening of the several switches is adjusted by the pulse modulator to regulate the output voltage.

Paulkovich, J.; Rodriguez, G. E. (inventors)

1981-01-01

121

Radiation effects on DC-DC Converters  

NASA Technical Reports Server (NTRS)

DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

2000-01-01

122

Series Connected Buck-Boost Regulator  

NASA Technical Reports Server (NTRS)

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.

Birchenough, Arthur G. (Inventor)

2006-01-01

123

A novel unified average model for single switch DC-DC converter  

Microsoft Academic Search

This paper introduces a novel unified average model for all single switch DC-DC converters, including buck, boost, buck-boost, forward and flyback converters. Because of its average feature, it can increase the simulation speed significantly. Commonly, it can increase the speed up to two to three orders. The model can also be operated in voltage, peak current and average current control

Yuancheng Ren; Xiehua Wu; Zhaoming Qian; Ken Ruan

2000-01-01

124

Buck Creek River Flow Analysis  

NASA Astrophysics Data System (ADS)

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.

Dhanapala, Yasas; George, Elizabeth; Ritter, John

2009-04-01

125

Efficiency and EMI comparisons between prototyped 8 kW hard and soft switched buck choppers  

Microsoft Academic Search

Rapid reconfiguration makes power electronics-based DC distribution systems attractive for systems that must be highly dependable. For systems at high power levels, the development of high-performance DC-DC converters is essential. In an attempt to assess efficiency, EMI, size and complexity, the authors have simulated, prototyped, and evaluated similar hard-switched and soft-switched 8 kW buck converters.

R. W. Ashton; J. G. Ciezki

2005-01-01

126

A Hamiltonian viewpoint in the modeling of switching power converters  

Microsoft Academic Search

In this paper we show how, using the Hamiltonian formalism, we can systematically derive mathematical models that describe the behaviour of a large class of switching power converters, including the “Boost”, “Buck”, “Buck-Boost”, “?uk” and “Flyback” converters. We follow the approach proposed by van der Schaft and Maschke and extract from the basic (energy-conserving) LC–circuit the remaining elements, i.e., resistors,

Gerardo Escobar; Arjan J. van der Schaft; Romeo Ortega

1999-01-01

127

Basic DC-to-DC Converters  

Microsoft Academic Search

This paper generically classifies and unifies basic single-switch, single-inductor, DC-TO-DC converters. The boost and buck\\/boost flyback converters are shown to be supplementary, each being part of the same three-port terminal transfer function. Realizing one of these converters inherently results in the other as a fully functional composite output port. Three-port examination of the forward converter reveals it too combines two

Barry W. Williams

2008-01-01

128

Transformerless dc-Isolated Converter  

NASA Technical Reports Server (NTRS)

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.

Rippel, Wally E.

1987-01-01

129

Buck-boost switched-capacitor DC-DC voltage regulator using delta-sigma control loop  

Microsoft Academic Search

This paper presents a delta-sigma control loop for a buck-boost DC-DC converter with fractional gains. The charge pump used to convert the input voltage acts as a D\\/A converter in the loop, and its output ripple is frequency shaped by the loop, which also provides the pulse frequency modulation needed for the conversion. Simulation results show that the delta-sigma loop

A. Rao; W. Mcintyre; J. Parry; Un-ku Moon; Gabor C. Temes

2002-01-01

130

Application of EXCEL for analyzing DC\\/DC converters  

Microsoft Academic Search

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

Peter H. WURM; Felix A. HIMMELSTOSS

1998-01-01

131

A TEG Efficiency Booster with Buck-Boost Conversion  

NASA Astrophysics Data System (ADS)

A thermoelectric generator (TEG) efficiency booster with buck-boost conversion and power management is proposed as a TEG battery power conditioner suitable for a wide TEG output voltage range. An inverse-coupled inductor is employed in the buck-boost converter, which is used to achieve smooth current with low ripple on both the TEG and battery sides. Furthermore, benefiting from the magnetic flux counteraction of the two windings on the coupled inductor, the core size and power losses of the filter inductor are reduced, which can achieve both high efficiency and high power density. A power management strategy is proposed for this power conditioning system, which involves maximum power point tracking (MPPT), battery voltage control, and battery current control. A control method is employed to ensure smooth switching among different working modes. A modified MPPT control algorithm with improved dynamic and steady-state characteristics is presented and applied to the TEG battery power conditioning system to maximize energy harvesting. A 500-W prototype has been built, and experimental tests carried out on it. The power efficiency of the prototype at full load is higher than 96%, and peak efficiency of 99% is attained.

Wu, Hongfei; Sun, Kai; Zhang, Junjun; Xing, Yan

2013-07-01

132

Evaluation function comparison of particle swarm optimization for buck converter  

Microsoft Academic Search

PID controller has been frequently applied to various application areas because of mathematical definition and overall performance which is greatly depended on accuracy of the control parameters. Therefore, conventional and evolutionary algorithms have introduced to find these parameters as tuning methods. In present evolutionary algorithms have frequently used in PID tuning applications. However, the tuning performance greatly depends on the

O. T. Altinoz; H. Erdem

2010-01-01

133

A 92%-efficiency wide-input-voltage-range switched-capacitor DC-DC converter  

Microsoft Academic Search

The traditional inductor-based buck converter has been the dominant design for step-down switched-mode voltage regulators for decades. Switched-capacitor (SC) DC-DC converters, on the other hand, have traditionally been used in low-power (<10mW) and low-conversion-ratio (80% over a load range of 5mA to 1A) than surveyed competitive buck converters, while requiring less board area and less costly passive components. The topology

Vincent Ng; Seth Sanders

2012-01-01

134

Modulation of three-level Z-source indirect matrix converter  

Microsoft Academic Search

This paper proposes an actively controlled three-level Z-source matrix converter with capability of performing output voltage buck-boost, and producing sinusoidal input-output quantities. The converter is in principle realized by inserting a Z-source impedance network to the dc-link of the otherwise voltage-buck only indirect matrix converter (IMC), formed by cascading a front-end current source rectifier and a rear-end three-level inverter together.

Xiong Liu; Poh Chiang Loh; Fang Zheng Peng; Peng Wang; Feng Gao

2010-01-01

135

Analysis of three phase PWM buck rectifier under modulation magnitude and angle control  

Microsoft Academic Search

The analysis of the steady-state, dynamic, and small-signal performance of a three-phase AC\\/DC buck rectifier using pulse width modulation (PWM) with modulation magnitude and angle control is presented. General equations of the converter including switching discontinuities are derived and used for transient and dynamic simulations. From these nonlinear equations, using the concept of existence function and synchronous reference frame d-q-o

Olorunfemi Ojo; Ishwar Bhat

1993-01-01

136

Low-Frequency Characterization of Switched dc-dc Converters  

Microsoft Academic Search

Averaging techniques are developed to represent buck, boost, and buck-boost types of switched dc-dc converters by approximate continuous models. Simple analytical expressions in terms of the circuit components are derived for the characteristic transient and frequency responses of time-average(continuous) power-stage models for use in designing and understanding the behavior of corresponding switched power stages. Novel conclusions include the dependence of

G. W. Wester; R. D. Middlebrook

1973-01-01

137

Efficient, lightweight dc/dc switching converter  

NASA Technical Reports Server (NTRS)

Converters have input properties of boost power stage and output properties of buck power stage, yet they perform general conversion function with high efficiency. Other features include non-pulsating input/output currents, use of capacitive energy transfer, low output voltage ripple, reduced EMI, and small size.

Cuk, S.; Middlebrook, R. D.

1981-01-01

138

Controlled doe exposure as biostimulation of buck rabbits.  

PubMed

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 White, 15-month-old, sexually experienced and fertile. Experimental design was completely random with nine replications, experimental unit was one buck. Doe exposure was permanent using replacement pubertal does housed in an adjacent wire-mesh cage and changed for new ones every other week. Semen collection lasted 14 weeks (late winter and early spring) twice a week with two ejaculates at each collection. Analyses of variance were under a mixed model: treatments, ejaculate number and season were fixed and rabbit random effects and buck weight at each collection as covariable. Biostimulated bucks showed greater (P<0.05) reproductive potential due to: 7% lesser reaction time (greater libido); and increased semen volume (40%), sperm motility (29%), sperm per ejaculate (31%), normal alive motile sperm (65%) and number of semen doses (64%). Semen characteristics differed by season in control bucks but not in doe exposed bucks (treatment × ejaculate number, P<0.05). Reproductive potential in spring was greater (P<0.05) than in winter in both treatments. Doe exposure is a biostimulation method that improves sexual drive and sperm production and quality of buck rabbits. PMID:20926210

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

2010-12-01

139

Radiation Effects on DC-DC Converters  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

140

Research on the implementation of a novel switching converter's controller  

Microsoft Academic Search

The DC-DC buck converter is token as the controlled object, and a neural network controller is designed for this converter, hardware implementation of the controller is discussed based on FPGA. The reconfigurable feature of the the neural network controller is analyzed, several reconfigurable unit is given, the implementation model of this controller is set up based on the SG \\/

Zhao Li; Li Tai

2010-01-01

141

A review of single-phase PFC topologies based on the boost converter  

Microsoft Academic Search

The need for solid-state ac-dc converters to improve power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input ac mains, and precisely regulated dc output have motivated the proposal of several topologies based on classical converters such as buck, boost, and buck-boost. Additionally, novel control techniques dedicated to PFC have also been introduced, motivating the manufacturing

J. P. M. Figueiredo; F. L. Tofoli; B. L. A. Silva

2010-01-01

142

Comparative Performance of Isolated Forward and Flyback AC-DC Converters for Low Power Applications  

Microsoft Academic Search

This paper addresses several issues concerning the modeling and application of single-phase, single switch, power factor corrected AC-DC high frequency switching converter topologies with transformer isolation. A detailed analysis, simulation and development are presented for forward buck and flyback buck-boost converters with high frequency isolation in discontinuous conduction mode (DCM) operation. To verify and investigate the design and performance at

B. Singh; G. D. Chaturvedi

2008-01-01

143

Optimal feed-forward compensation for PWM DC\\/DC converters  

Microsoft Academic Search

An analytical procedure for optimizing the feedforward compensation for any PWM (pulse width modulation) DC-DC converter is described. The aim of achieving zero DC audio-susceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation

L. Calderoni; L. PinolaO; V. Varoli

1990-01-01

144

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

NASA Technical Reports Server (NTRS)

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.

Thornton, Trevor; Lepkowski, William; Wilk, Seth

2013-01-01

145

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

Federal Register 2010, 2011, 2012, 2013

...Buck Island Reef National Monument, Virgin Islands AGENCY: National Park Service...Buck Island Reef National Monument, Virgin Islands...for Buck Island Reef National Monument, Virgin Islands. [[Page 12324

2012-02-29

146

Component-Minimized Buck-Boost Voltage Source Inverters  

Microsoft Academic Search

This paper presents the design of buck-boost B4 inverters that can be derived from either Cuk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion. In order to form a distinct neutral potential in the corresponding voltage boost circuitry for correct B4 inverter operation,

F. Gao; P. C. Loh; F. Blaabjerg; R. Teodorescu; D. M. Vilathgamuwa

2007-01-01

147

Diode-assisted buck-boost voltage source inverters  

Microsoft Academic Search

This paper proposes buck-boost voltage source inverters with a unique X-shape diode-capacitor network inserted between inverter circuitry and dc source for producing a large voltage boost gain. Comparing with other voltage buck-boost techniques, the presented topologies with only a little more passive components can significantly enhance voltage boost capability for dc-ac inversion. With different front-end circuitries, the diode-assisted buck-boost inverters

F. Gao; P. C. Loh; R. Teodorescu; F. Blaabjerg

2007-01-01

148

A Current Fed Two-Inductor Boost Converter With an Integrated Magnetic Structure and Passive Lossless Snubbers for Photovoltaic Module Integrated Converter Applications  

Microsoft Academic Search

In this paper, a photovoltaic (PV) module integrated converter is implemented with a current fed two-inductor boost converter cascaded with a line frequency unfolder. The current source is a sinusoidally modulated two-phase buck converter with an interphase transformer. The boost cell operates at a fixed duty ratio and has an integrated magnetic structure. The two inductors and the transformer are

Quan Li; Peter Wolfs

2007-01-01

149

Current feedback in DC\\/DC converters by using toroidal transformers  

Microsoft Academic Search

A new current feedback method in DC\\/DC converters by using toroidal transformers is proposed. In most of the DC\\/DC converters the current provided to the load is composed of two components that run over different wires. In all these configurations, for instance buck, boost, Cuk, forward and push-pull converters, the proposed feedback method can be applied

M. Sanz; A. Llombart; J. Sallan

1996-01-01

150

Nonlinear control of flyback type DC to DC converters: An indirect backstepping approach  

Microsoft Academic Search

Flyback type DC to DC converters are basically a transformer-isolated version of the standard buck-boost converter. In this work, a nonlinear control methodology for the flyback type DC to DC converter is proposed. The proposed method uses a backstepping approach to regulate the corresponding current required to set the output voltage to its desired value as opposed to directly regulating

Murat Seker; Erkan Zergeroglu

2011-01-01

151

Geology Fieldnotes: Buck Island Reef National Monument, Virgin Islands  

NSDL National Science Digital Library

This National Park Service (NPS) site covers the geology of Buck Island Reef National Monument in the Virgin Islands. It discusses coral reef formation and characteristics, as well as the history of Buck Island. There are links for maps, visitor information, and more details about this monument.

152

Sinusoidal internal model based control of a three-phase voltage source rectifier with buck-boost operation  

Microsoft Academic Search

A rectifier system having a DC voltage step-up and step-down characteristic is treated. The system consists of a PWM voltage source rectifier and a DC-to-DC buck converter connected in cascade. Theoretically, the system can produce a DC output voltage ranging from zero volts to infinity and a sinusoidal AC input current, and the displacement power factor can be kept at

Atsushi Moki; Shoji Fukuda

2003-01-01

153

Protection et Regulation sur les Convertisseurs Continu-Continu a Decoupage (Protection and Regulation on Direct-Direct Chopping Converters).  

National Technical Information Service (NTIS)

The mathematical modeling of current protection and voltage regulation systems with different types of switching cells such as buck, boost, flyback, forward and current fed DC/DC converters is presented. Two original current sensors are also studied: they...

A. Barnaba

1992-01-01

154

Analysis and design of an adaptive multi-loop controlled two winding buck/boost regulator  

NASA Technical Reports Server (NTRS)

Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design guidelines are formulated to optimize regulator-loop dependent characteristics.

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

1979-01-01

155

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

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

156

Improved power quality three phase AC-DC converter  

Microsoft Academic Search

Because of increasing applications of power electronic ac-dc converters, it's necessary to implement the single stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double stage conversion (ac\\/dc-dc\\/dc) but ultimately leading to less efficiency and complex control. The novel ac-dc impedance-source converter, abbreviated as Z-source rectifier, has high power quality level and

Seyed Hossein Hosseini; F. Sedaghati; M. Sarhangzadeh

2010-01-01

157

Optimal feed-forward compensation for PWM DC\\/DC converters with `linear' and `quadratic' conversion ratio  

Microsoft Academic Search

An analytical procedure to optimize the feedforward compensation for any PWM DC\\/DC power converters is described. Achieving zero DC audiosusceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation of the hardware-introduced errors are

Luigi Calderone; Licia Pinola; Vincenzo Varoli

1992-01-01

158

Optimal feed-forward compensation for PWM dc/dc converters with 'linear' and 'quadratic' conversion ratio  

NASA Astrophysics Data System (ADS)

The paper describes an analytical procedure to optimize the feed-forward compensation for any PWM dc/dc converters. The aims of achieving zero dc audiosusceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation of the hardware-introduced errors are discussed. A PWM controller implementing the optimal feed-forward compensation for buck-boost, Cuk, and SEPIC cells is described and fully experimentally characterized.

Calderone, Luigi; Pinola, Licia; Varoli, Vincenzo

1992-04-01

159

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

Microsoft Academic Search

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

Keping You; M. F. Rahman

2005-01-01

160

A Current Fed Two-Inductor Boost Converter with Lossless Snubbing for Photovoltaic Module Integrated Converter Applications  

Microsoft Academic Search

In this paper, a photovoltaic module integrated converter (MIC) is implemented with a current fed two-inductor boost converter cascaded with a line frequency unfolder. The two-inductor boost cell is fed from a sinusoidally modulated two-phase buck converter with an interphase transformer and operates at a fixed duty cycle. The boost cell features the magnetic integration approach to combine the three

Quan Li; Peter Wolfs

2005-01-01

161

Single-Phase AC–AC Converter Based on Quasi-Z-Source Topology  

Microsoft Academic Search

This paper deals with a new family of single-phase ac-ac converters called single-phase quasi-Z-source ac-ac converters. The proposed converter inherits all the advantages of the traditional single-phase Z-source ac-ac converter, which can realize buck-boost, reversing, or maintaining the phase angle. In addition, the proposed converter has the unique features that the input voltage and output voltage share the same ground

Minh-Khai Nguyen; Young-Gook Jung; Young-Cheol Lim

2010-01-01

162

Passivity-Based Controllers for the Stabilization of DC-to-DC Power Converters  

Microsoft Academic Search

Passivity--based feedback controllers are derived for the indirect stabilization of the averageoutput voltage in Pulse--Width--Modulation (PWM) controlled dc--to--dc power converters of the"boost", "buck--boost" and "buck" types. The controller design is carried out on the basis of wellknown average PWM models of such circuits. These models are shown to be Euler--Lagrange systemscorresponding to a suitable set of average Euler--Lagrange parameters. The

Hebertt Sira-ramírez; Romeo Ortega

1997-01-01

163

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

Microsoft Academic Search

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

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

2003-01-01

164

Analysis of interleaved converters with WTA-based switching  

Microsoft Academic Search

This paper presents interleaved buck converters using a switching rule based on winner-take-all nonlinearity. The switching rule can realize flexible phase control and the sys- tem can generate various interesting synchronous phenom- ena. Using a simple piecewise constant model, we clarify parameters conditions for existence and stability of the phe- nomena. We also discuss current sharing and ripple reduc- tion

Toshimichi Saito; Masanori Yoshizawa; Hiroyuki Torikai; S. Tazaki

2002-01-01

165

Soft switching active snubbers for DC/DC converters  

SciTech Connect

A soft-switching active snubber is proposed to reduce the turn-off losses of the insulated gate bipolar transistor (IGBT) in a buck converter. The soft-switching snubber provides zero-voltage switching for the IGBT, thereby reducing its high turn-off losses due to the current tailing. The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary switch also operates at zero-voltage and zero-current switching. The size of the auxiliary switch compared to the main switch makes this snubber a good alternative to the conventional snubber or even to passive low-loss snubbers. The use of the soft-switching active snubber permits the IGBT to operate at high frequencies with an improved RBSOA. In the experimental results reported for a 1 kW, 40 kHz prototype, combined switching/snubbing losses are reduced by 36% through the use of the active snubber compared to a conventional RCD snubber. The use of an active snubber capacitor during turn-off. The generic snubber cell for the buck converter is generalized to support the common nonisolated dc/dc converters (buck, boost, buck-boost, Cuk, sepic, zeta) as well as isolated dc/dc converters (forward, flyback, Cuk, and sepic).

Elasser, A.; Torrey, D.A. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Electric Power Engineering] [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Electric Power Engineering

1996-09-01

166

Protection and regulation on direct-direct chopping converters  

NASA Astrophysics Data System (ADS)

The mathematical modeling of current protection and voltage regulation systems with different types of switching cells such as buck, boost, flyback, forward and current fed DC/DC converters is presented. Two original current sensors are also studied: they are used in the regulation and the protection of current loops. Their implementation and the associated test results are shown.

Barnaba, Alphonse

1992-01-01

167

Protection and regulation on direct-direct chopping converters  

Microsoft Academic Search

The mathematical modeling of current protection and voltage regulation systems with different types of switching cells such as buck, boost, flyback, forward and current fed DC\\/DC converters is presented. Two original current sensors are also studied: they are used in the regulation and the protection of current loops. Their implementation and the associated test results are shown.

Alphonse Barnaba

1992-01-01

168

A general unified approach to modelling switching dc-to-dc converters in discontinuous conduction mode  

NASA Technical Reports Server (NTRS)

A method for modelling switching converters in the discontinuous conduction mode is developed, whose starting point is the unified state-space representation, and whose end result is a complete linear circuit model 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 operating in the discontinuous conduction mode, 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.

Cuk, S.; Middlebrook, R. D.

1977-01-01

169

An isolated single stage buck-boost inverter  

Microsoft Academic Search

This paper presents a novel isolated single stage buck-boost inverter for implementing dc-to-ac, ac-to-dc or dc-to-dc. The BBI has better performances, in terms of low cost, high efficiency and high voltage gain. Through the HEV\\/EV application, the circuit operation principles and characteristics have been analyzed. And then, a novel Synchro-Switching SVPWM have been presented to obtain the maximum buck-boost factor

Liang-hua Zhang; Xu Yang; Xiaofeng Yao

2008-01-01

170

NONSMOOTH DYNAMICS AND FPIC CHAOS CONTROL IN A DC-DC ZAD-STRATEGY POWER CONVERTER  

Microsoft Academic Search

Nonsmooth phenomena such as discontinuity-induced bifurcations, due to saturations and switchings are re- ported in a power converter. They lead to chaos when a significant parameter is varied. Then, in this paper a novel tool for controlling chaos in a dynamical sys- tem is designed and applied to a buck converter driven with a PWM centered pulse and (Zero Average

Fabiola Angulo; Gerard Olivar; John A. Taborda; Fredy E. Hoyos

2008-01-01

171

A step-down conversion concept for a PWM-mode boost converter  

Microsoft Academic Search

A new area efficient approach for regulating the output of boost converters even when the input voltage exceeds the output voltage is presented. Down conversion is achieved without using an LDO and does not require an additional inductor coil and capacitor like the SEPIC or other noninverting buck-boost converters. The concept is based on a back-gate control of the PMOS

Christian V. Schimpfle; Jorg Kirchner

2003-01-01

172

Sliding mode-a new way to control series resonant converters  

Microsoft Academic Search

The application of the theory of variable structure control systems for the control of resonant DC-DC converters is illustrated. The full-bridge configuration of series-resonant converters (SRCs) is used. The converter is operated at resonant frequency to obtain both output-to-input voltage characteristics similar to those of the buck converter and high efficiency. To arrive at an exact mathematical model, the SRC

Fares BOUDJEMA; Jean-Louis ABATUT

1990-01-01

173

Optimal modulation of indirect Z-source matrix converter  

Microsoft Academic Search

Z-source energy conversion is a recent concept introduced for adding voltage-boost functionality to the otherwise buck-only dc-ac inverter. The same concept can equally be extended to other converter topologies including the indirect ac-ac matrix converter, where only a single Z-source impedance network needs to be inserted to its intermediate dc-link. Because of such a simple insertion, topological extension of the

Xiong Liu; Poh Chiang Loh; Fang Zheng Peng; Peng Wang

2010-01-01

174

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

NSDL National Science Digital Library

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.

2008-10-06

175

Wrongs of Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

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.

2008-10-06

176

Steady-state analysis of AC-to-DC converters with active input current shaper based on delayed forward output  

Microsoft Academic Search

This paper deals with the steady-state analysis of AC-to-DC converters which use the recently proposed active input current shaper (AICS) to reduce the line current harmonics in order to comply with the IEC 1000-3-2 specifications. The main equations for many topologies directly derived from the standard ones (forward, flyback, SEPIC, Cuk, half-bridge, full-bridge, push-pull, buck, boost, buck-boost, etc.) have been

J. Sebastiiin; A. Ferniindez; P. Villegas; A. M. Pernia

1999-01-01

177

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

NSDL National Science Digital Library

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.

2008-10-06

178

Comparison of z-source and boost-buck inverter topologies as a single phase transformer-less photovoltaic grid-connected power conditioner  

Microsoft Academic Search

In PV grid connected power conditioners; usually is required to step up the PV array voltage, and to step down the DC bus voltage for injection of a sinusoidal current to the grid. In this paper, the design procedure of the traditional double stage boost-buck inverter and single stage z-source converter, as a single phase PV grid connected transformer-less power

Babak Farhangi; Shahrokh Farhangi

2006-01-01

179

Three-Phase Ac Buck Rectifier using Normally-On SiC JFETs at 150 kHz Switching Frequency  

Microsoft Academic Search

For many applications of high-performance three- phase AC converters, silicon carbide (SiC) switching devices promise breakthroughs in performance and power density. The SiC JFET technology is maturing, and will likely be the first SiC power switch available for applications requiring blocking voltages on the order of 1 kV. In this paper, a 2 kW three-phase buck rectifier with 150 kHz

Callaway J. Cass; Rolando Burgos; Fred Wang; Dushan Boroyevich

2007-01-01

180

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

Microsoft Academic Search

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%

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

2010-01-01

181

A Charge-Recycling Buck-Store and Boost-Restore (BSBR) Technique With Dual Outputs for RGB LED Backlight and Flashlight Module  

Microsoft Academic Search

A boost converter with buck-store and boost-restore (BSBR) technique fabricated by 0.25 mum CMOS BCD process can provide different supply voltages to drive series red, green, and blue LEDs in sequence for reducing the power consumption on the constant current generator. The proposed technique not only stores and restores extra energy during the transient time of the reference tracking response

Chun-Yu Hsieh; Chih-Yu Yang; Ke-Horng Chen

2009-01-01

182

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

183

Transformerless dc-to-dc converters with large conversion ratios  

NASA Astrophysics Data System (ADS)

A novel switching dc-dc converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the Cuk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50-V to 5-V converter in which dc isolation is not required. The absence of a transformer and the larger duty ratio permit operation at a high switching frequency and make the circuit amenable to partial integration and hybrid construction techniques. An experimental 50-W three-stage voltage-divider Cuk converter converts 50 V to 5 V at 500 kHz, with efficiency higher than for a basic Cuk converter operated at the same conditions. A corresponding voltage-multiplier Cuk converter is described, as well as dual buck-boost-derived step-down and step-up converters.

Middlebrook, R. D.

1988-10-01

184

Dynamic Analysis of a Bidirectional Switched Capacitor DC\\/DC Converter for Fuel Cell Vehicle Energy Storage Applications  

Microsoft Academic Search

This paper focuses on the novel controller design and analysis for a fuel cell vehicle energy storage system energy management system, based on a hybrid switched-capacitor (SC) bidirectional DC\\/DC converter topology. The novel control strategy enables simpler dynamics compared to a standard buck converter with input filter, which is essential for fuel cell based energy storage systems. Moreover, the controller

Zahra Amjadi; Sheldon S. Williamson

2009-01-01

185

A CURRENT FED TWO-INDUCTOR BOOST CONVERTER FOR GRID INTERACTIVE PHOTOVOLTAIC APPLICATIONS  

Microsoft Academic Search

A current fed two-inductor boost converter is combined with a low frequency unfolder stage to produce a Module Integrated Converter (MIC) for photovoltaic applications. A two-phase buck converter with an interphase transformer is modulated to produce a rectified sinusoid waveform as an input to the fixed duty cycle two-inductor boost cell. The boost cell features an integrated magnetics approach to

Quan Li; Peter Wolfs

186

Study and implementation of a single-phase isolated AC-DC converter  

Microsoft Academic Search

A single-phase isolated AC-DC converter is presented in this paper. The front semi-stage, which is a modified buck-boost converter, is used for power factor correction and is operated in discontinuous conduction mode (DCM) to achieve high power factor and low total harmonic distortion of input current. The rear semi-stage, which is a forward converter, is operated in DCM for step-down

Lung-Sheng Yang; Chia-Ching Lin; Ming-Rong Lee

2012-01-01

187

The research of multiple-output SR-forward converter with voltage regulation  

Microsoft Academic Search

The design principle of a kind of SR multiple-output DC\\/DC converter is discussed in this paper, based on the single end forward converter. The one-cycle control method of forward converter duty-ratio is explained. A new type of secondary loop SR-PWM regulator with SR-buck structure is brought forward in this paper, which has concisely achieved multiple-outputs

Shengfa Zhang; Xiancai Zhang; Qingyun Meng

2005-01-01

188

High-efficiency synchronous dual-output switched-capacitor dc-dc converter with digital state machine control  

Microsoft Academic Search

An integrated high-efficiency dual-output switched-capacitor (SC) DC-DC converter was presented. The converter is capable of synchronously providing a buck output voltage channel and a boost channel with shared three fly capacitors and a switch-array. Fully digital state machine controller and gain-hopping regulation technique endued the converter with high power efficiency, fast transient response and system steadiness. The converter was designed

Han Shiming; Wu Xiaobo; Liu Yang

2007-01-01

189

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

NSDL National Science Digital Library

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 ÃÂ 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.

2008-10-06

190

Mycoplasma agalactiae detected in the semen of goat bucks  

Microsoft Academic Search

Contagious agalactia (CA) is among the most significant diseases affecting small ruminant populations in Mediterranean countries. This study was designed to detect the excretion in semen of CA-causing mycoplasmas in goats (Capra hircus) reared in Spain, where the disease is considered endemic. Culture techniques and PCR were conducted on 147 semen samples collected from 113 goat bucks to detect mycoplasmas.

C. de la Fe; J. Amores; A. Gómez Martín; A. Sánchez; A. Contreras; J. C. Corrales

2009-01-01

191

Recognition of dynamic patterns in dc-dc switching converters  

NASA Astrophysics Data System (ADS)

Techniques are presented for analyzing the dynamic patterns of power flow in high-frequency dc-dc switching converters. Emphasis is placed on exploring methods for developing reduced-order models of power electronic circuits for simulation and state-space averaging. Tools from selective modal analysis are used to develop the dynamic pattern recognition algorithm that facilitates the classification of circuit modules. The algorithm is intended for the analysis of converters derived from the canonical switching call, i.e., the buck, boost, and flyback converters.

Leeb, Steven B.; Kirtley, James L.; Verghese, George C.

192

Diodes as pseudo active elements in high frequency dc/dc converters  

NASA Astrophysics Data System (ADS)

An approach to realizing zero-voltage switching in the entire family of high-frequency dc-dc converters is proposed. Utilizing the parasitic associated with the diode stored charge, it is shown that the diode reverse current established for charge removal can be used advantageously to accomplish soft switching. The resulting converter topologies differ from their hard-switched counterparts only by the presence of a resonant capacitor. Device and component stresses are moderate compared to existing quasi-resonant and resonant techniques. Converter analysis is complex as a result of the dominant diode nonlinearities, and no closed-form expressions are possible. Converter transfer characteristics are obtained through simulation, and operating limits are analytically obtained. The concept is validated by experimental results on buck, buck-boost, and boost converters rated approximately 100 W and operating at frequencies around 1 MHz.

Divan, D. M.

193

Direct repair of lumbar spondylolysis by Buck's technique  

PubMed Central

Background: The lesion in spondylolysis is a nonunion that follows a fatigue fracture of pars interarticularis. Direct repair of the pars defect is a logical alternative to fusion as it helps to preserve the motion segment and prevents abnormal stresses at the adjacent levels. The purpose of the study is to analyze the clinical and radiological results of direct screw osteosynthesis of the pars defect by the Buck’s method in patients with symptomatic spondylolysis with or without grade 1 spondylolisthesis. Materials and Methods: Nine patients (six males, three females, mean age 24 years) with symptomatic spondylolysis with or without grade 1 spondylolisthesis and a normal disc in magnetic resonance imaging (MRI), who failed conservative treatment, underwent surgery between January 2000 and April 2009. Of them five patients had bilateral lysis at one level, one had bilateral lysis at three levels and two levels each and two had unilateral lysis at one level. Direct pars repair by the Buck’s method with internal fixation of the defect using 4.5 mm cortical screws and cancellous bone grafting was done. The mean follow-up period was 45 months. MacNab criteria were used to evaluate the postoperative functional outcome. Healing of the pars defect was assessed by plain radiographs and computed tomography (CT) scan. Results: Spondylolysis was bilateral in seven and unilateral in two patients. Two patients had associated grade 1 spondylolisthesis. The mean operative time was 58 minutes (range 45 – 75 minutes) and blood loss was 98 ml (50 – 140 ml). Although radiological fusion was observed in all patients at a mean follow-up of 45 months (range 9 to 108 months), the functional outcome was excellent in two patients and good in five, with one fair and one poor result. The overall result of the procedure was satisfactory in 78% (7/9) of the patients. The two patients with associated grade 1 spondylolisthesis had fair and poor results. No complications were encountered in the perioperative or postoperative period. Conclusions: In carefully selected patients, direct repair of the pars defect by the Buck’s technique of internal fixation and bone grafting was a safe and effective alternative to fusion in younger patients with symptomatic spondylolysis, without associated spondylolisthesis, who failed conservative management.

Rajasekaran, S; Subbiah, M; Shetty, Ajoy Prasad

2011-01-01

194

Performance evaluation of silicon carbide devices in power converters  

Microsoft Academic Search

Commercial silicon carbide (SiC) Schottky and PIN diodes, and JFETs were characterized for static conduction and dynamic switching performances in hard- and soft-switching buck converters. The results are compared with the measured data obtained from similarly rated silicon and GaAs devices. It is shown that for low-voltage rectifiers the only real advantage of SiC over silicon and GaAs is the

Krishna Shenai; Philip G. Neudeck

2000-01-01

195

Soft switching active snubbers for DC\\/DC converters  

Microsoft Academic Search

A soft-switching active snubber is proposed to reduce the turn-off losses of the insulated gate bipolar transistor (IGBT) in a buck power converter. The soft-switching snubber provides zero-voltage switching for the IGBT, thereby reducing its high turn-off losses due to the current tailing. The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary switch also operates

A. Elasser; D. A. Torrey

1996-01-01

196

PFC Cuk converter based electronic ballast for an 18 W compact fluorescent lamp  

Microsoft Academic Search

This paper deals with the design and performance simulation of high power factor (HPF), low crest factor electronic ballast for a compact fluorescent lamp (CFL). The proposed electronic ballast uses a Cuk buck-boost ac-dc converter in continuous conduction mode (CCM) as a power factor preregulator. In this electronic ballast topology, a self oscillating half bridge series resonant parallel loaded inverter

Ashish Shrivastava; Bhim Singh

2010-01-01

197

New control strategy for variable speed wind turbine with DC-DC converters  

Microsoft Academic Search

The paper studies the performance of variable speed wind turbine (VSWT) configuration with non-inverting buck-boost converter. The wind turbine systems consist of permanent magnet synchronous generator (PMSG) connected to diode rectifier, DC chopper and load. New control strategy, based on the maximum power point tracking (MPPT) and limited power point tracking (LPPT) algorithms is used to improve the system operation.

Vladimir Lazarov; Daniel Roye; Dimitar Spirov; Zahari Zarkov

2010-01-01

198

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

199

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

200

A rugged converter for use in low battery voltage uninterruptible power systems  

Microsoft Academic Search

This paper presents a power converter composed of a two switch buck boost power factor corrected AC\\/DC stage cascaded with a bi-directional asymmetric duty cycle half bridge forward stage for use in UPS systems with low battery voltage. Novel modulation strategies are used in both stages giving low switch stresses

Richard Morrison; Michael G. Egan

2000-01-01

201

Do wolves affect white-tailed buck harvest in northeastern Minnesota?  

USGS Publications Warehouse

We used simple linear regression to analyze 8-23 years of data on a wolf (Canis lupus) population and human harvest of white-tailed deer (Odocoileus virginianus) bucks in northeastern Minnesota to determine any effects of wolves on buck harvesting. Over the long term, wolves accounted for at least 14-22% of the inter-year variation in buck harvest in the region, but an unknown amount of variation in hunter effort may have obscured any more precise estimate. For part of the area with poorest habitat, we found strong inverse relationships (r2 = 0.66-0.84) between annual wolf numbers and buck harvests from 1988 to 1995 when hunting pressure was considered relatively constant. However, in better habitat, where our buck harvest sample was larger, we found no evidence of wolves influencing buck harvest. Our findings tend to confirm the suitability of the Minnesota Department of Natural Resource's deer harvest regulations for a sustainable yield.

Mech, L. D.; Nelson, M. E.

2000-01-01

202

Switched capacitor DC-DC converter in 65nm CMOS technology with a peak efficiency of 97%  

Microsoft Academic Search

This paper presents a highly efficient switched capacitor (SC) DC-DC converter, which is implemented in a 65nm low power CMOS process to enable SoC integration. The converter supplies a nominal output current of 30mA with an efficiency of 95%. The buck converter operates with a constant input voltage of 1.83V and produces an output voltage of 1.2V. The charge is

Thomas Santa; Mario Auer; Christoph Sandner; Christian Lindholm

2011-01-01

203

Analysis and Design for a Novel Single-Stage High Power Factor Correction Diagonal Half-Bridge Forward AC–DC Converter  

Microsoft Academic Search

By means of components placement, the buck-boost and diagonal half-bridge forward converters are combined to create a novel single-stage high power factor correction (HPFC) diagonal half-bridge forward converter. When both the PFC cell and dc-dc cell operate in DCM, the proposed converter can achieve HPFC and lower voltage stress of the bulk capacitor. The circuit analysis of the proposed converter

Jong-Lick Lin; Wei-Kai Yao; Sung-Pei Yang

2006-01-01

204

Comparison of Power Quality Improvement techniques in AC-DC Cuk Converter  

Microsoft Academic Search

The Improved Power Quality AC-DC Converters (IPQCs) provides enhanced power quality in terms of improved power factor and reduced Total Harmonic Distortion (THD) at the utility interface. This paper addresses comparison of power factor correction techniques for high frequency isolation based single phase Buck-Boost AC-DC Cuk Converter, which consists of only one switch resulting in reduced THD and improved power

J. Gnanavadivel; Vidhya Chellappa; N. Senthil Kumar

2011-01-01

205

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

Microsoft Academic Search

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

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

1992-01-01

206

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

Microsoft Academic Search

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

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

2007-01-01

207

Analysis of the Two-Switch Forward Converter with Synchronous Current Doubler Rectifier  

Microsoft Academic Search

A soft switching two-switch forward converter is presented to achieve zero voltage switching turn-on of switching devices. In the adopted converter, a buck-boost type of active clamp is connected in parallel with the primary winding of transformer. The energy stored in the transformer leakage inductance and magnetizing inductance can be recovered so that the peak voltage stress of switching devices

Bor-Ren Lin; Jin-Fa Wan; Chien-Lan Huang; Huann-Keng Chiang

2007-01-01

208

Modelling, Simulation, Fabrication, Experiments and Real-Time Linear State Variable Feedback Control of Cuk Converter using Pole Placement Technique  

NASA Astrophysics Data System (ADS)

Using a suitable combination of some of the basic converter topologies representing the Buck, the Boost and the Buck-Boost converters, one may obtain some other useful dc-to-dc converters. A typical example is the cascade connection of the Boost and the Buck converter which produces the well known Cuk converter. This work emphasises on the modelling, real-time simulations, fabrication and closed-loop control of a Cuk converter. For the modelling and real time simulation, FPGA platform has been used. Small signal modelling and conventional control aspects (compensator) of Cuk converter are discussed. A 200W, 10kHz Cuk converter is designed, fabricated and tested in the laboratory. The converter model is of fourth order. The transfer function being a non-minimum phase one with two right-half plane zeroes, a limited work has been done on this. For such systems, conventional control methods are demonstrated to fail. Pole placement technique, which is envisaged to be a suitable control technique for a higher order non-minimum phase system has been adopted. Excellent correlation between off-line and real-time simulation results establishes the accuracy of the work. Agreement between open-loop results obtained from the experimental set-up under steady state vis-a-vis those obtained from simulation is also a major highlight of the paper.

Nanda, S.; Sengupta, M.; Sengupta, A.

2014-05-01

209

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

NSDL National Science Digital Library

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.

2008-10-06

210

Low Temperature Operation of a Switching Power Converter  

NASA Technical Reports Server (NTRS)

The low temperature operation of a 48 W, 50 kHz, 36/12 V pulse width modulated (PWM) buck de-de power converter designed with standard commercially available components and devices is reported. The efficiency of the converter increased from 85.6% at room temperature (300 K) to 92.0% at liquid nitrogen temperature (77 K). The variation of power MOSFET, diode rectifier, and output filter inductor loss with temperature is discussed. Relevant current, voltage. and power waveforms are also included.

Anglada-Sanchez, Carlos R.; Perez-Feliciano, David; Ray, Biswajit

1997-01-01

211

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

NSDL National Science Digital Library

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.

2008-10-06

212

FINAL REPORT OF THE STUDY OF POST HIGH SCHOOL EDUCATION NEEDS IN BUCKS COUNTY, 1968-1980. VOLUME II.  

ERIC Educational Resources Information Center

FIVE WORKING PAPERS PREPARED FOR A STUDY TO DETERMINE POST-HIGH SCHOOL EDUCATIONAL NEEDS IN BUCKS COUNTY AND COURSES OF ACTION FOR MEETING THEM ARE PRESENTED--(1) "POST-HIGH SCHOOL EDUCATIONAL RESOURCES IN AND AROUND BUCKS COUNTY, PENNSYLVANIA, (2) "CHARACTERISTICS OF HIGH SCHOOL SENIORS, BUCKS COUNTY, PENNSYLVANIA," (3) "HIGH SCHOOL SENIOR…

BREWIN, CHARLES E., JR.; PARKER, JOHN K.

213

Bucking the Trend, St. John's University Converts Instructors into Tenure-Track Professors  

ERIC Educational Resources Information Center

Scholars who teach composition, a staple on the schedule of many a college freshman, often wind up stringing together a series of adjunct teaching jobs while keeping an eye out for that first step on the golden track to tenure. This article reports on a group of 20 people hired by St. John's University to teach in its first-year writing program,…

June, Audrey Williams

2009-01-01

214

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

Microsoft Academic Search

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-

Man Pun Chan; Philip K. T. Mok

2011-01-01

215

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

NASA Astrophysics Data System (ADS)

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.

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki

2012-12-01

216

Thermophotovoltaic converter  

SciTech Connect

A thermophotovoltaic converter of the type comprising a concentrating optical system and a transducer for solar radiation provided with at least one lens and with at least one photovoltaic cell is described. The principal feature of this converter is that the aforementioned transducer comprises at least a radiator having an irradiating surface substantially facing the sensitive surface of the photovoltaic cell and a selective filter disposed between the photovoltaic cell and the aforementioned radiator.

Boero, A.; Demichelis, F.; Ferrari, G.; Minetti-mezetti, E.; Palazzetti, M.

1982-05-25

217

Feeding and reproductive behaviour in fallow bucks (Dama dama)  

NASA Astrophysics Data System (ADS)

Observations on individually marked fallow deer (Dama dama) in central Italy were performed over 2 years in order to analyse time budgets of four age and sex classes. The aim was to test whether feeding activity was influenced by mating activity, forage quality or physiological constraints during the rut. Only adult males (bucks) completely ceased feeding during the rutting season, well before the actual start of mating behaviour and concurrently with the phenomenon of scent-urination, and spending most of their daily time completely inactive. All other age and sex classes were unaffected in their feeding behaviour by the rutting season. Indeed, females and young males showed a marked increase in grazing in response to an improvement in forage quality from summer to autumn. These results seem to confirm the hypothesis that hypophagia, displayed only by bucks, may be of no adaptive value in itself. On the other hand, it may be a by-product of other physiological processes occurring during the rut, inducing scent-urination, which plays an important role in intraspecific recognition and sexual attraction.

Apollonio, Marco; Vittorio, Irene

2004-12-01

218

Mycoplasma agalactiae detected in the semen of goat bucks.  

PubMed

Contagious agalactia (CA) is among the most significant diseases affecting small ruminant populations in Mediterranean countries. This study was designed to detect the excretion in semen of CA-causing mycoplasmas in goats (Capra hircus) reared in Spain, where the disease is considered endemic. Culture techniques and PCR were conducted on 147 semen samples collected from 113 goat bucks to detect mycoplasmas. No animal showed clinical symptoms of CA at the moment of the screening. M. agalactiae was identified using both diagnostic methods in three semen samples collected from three different bucks. These animals belonged to a group of animals in which semen had been analyzed twice and only the second sample proved positive, suggesting the possibility of intermittent excretion. This is the first report of the isolation of M. agalactiae from semen collected from naturally infected goats. Future studies should investigate whether semen could be a real source of CA infection by determining if the agent may be transmitted during natural service or when semen is used for artificial insemination. PMID:19773063

de la Fe, C; Amores, J; Martín, A Gómez; Sánchez, A; Contreras, A; Corrales, J C

2009-12-01

219

Thermionic converter  

DOEpatents

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.

Fitzpatrick, Gary O. (Livermore, CA)

1987-05-19

220

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

Microsoft Academic Search

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

Vincent W Ng; Michael D Seeman; Seth R Sanders

2009-01-01

221

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

Microsoft Academic Search

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

Sudip K. Mazumder; Muhammad Tahir; Kaustuva Acharya

2008-01-01

222

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

Microsoft Academic Search

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

Aleksandar Prodic; Dragan Maksimovic; Robert W. Erickson

2001-01-01

223

Suppression of the input current harmonics and output voltage ripple using the novel multiple-input AC-DC converter  

Microsoft Academic Search

This paper presents a novel method to suppress the input current harmonics and low frequency output voltage ripple using a multiple-input AC-DC power converter. The proposed circuit is fundamentally composed of the multiple-input DC-DC power converter, which is divided broadly into two circuit types; i.e., buck-boost and forward. From view points of the relatively small power application and simple circuit

H. Matsuo; F. Kurokawa; Byunghoon Lee; K. Akise

1997-01-01

224

TAXONOMY OF PSEUDOMONAS PISCICIDA (BEIN) BUCK, MEYERS, AND LEIFSON.  

PubMed

Hansen, A. J. (University of Idaho, Moscow), O. B. Weeks, and R. R. Colwell. Taxonomy of Pseudomonas piscicida (Bein) Buck, Meyers, and Leifson. J. Bacteriol. 89:752-761. 1965.-Twenty strains of marine bacteria showing the properties of pigmentation and icthyotoxicity were studied for selected physiological features. A quantitative taxonomic analysis with an electronic computer was performed. Eighteen species of Pseudomonas were included in the computer analysis as reference strains. The marine collection formed a homogeneous cluster, 80% similarity, and showed a 67 to 70% similarity to certain of the Pseudomonas species: P. atlantica, P. geniculata, P. synxantha, and P. taetrolens. The marine strains are treated as a phenon describing the species P. piscicida. The species was characterized by the hypothetical Median Organism concept; P. piscicida 14 corresponded most closely to the Median Organism. PMID:14273657

HANSEN, A J; WEEKS, O B; COLWELL, R R

1965-03-01

225

Lossless Dynamic Models of the Quasi-Z-Source Converter Family  

NASA Astrophysics Data System (ADS)

This paper is devoted to the quasi-Z-source (qZS) converter family. Recently, the qZS-converters have attracted attention because of their specific properties of voltage boost and buck functions with a single switching stage, which could be especially beneficial in renewable energy applications. As main representatives of the qZS-converter family, the traditional quasi-Z-source inverter as well as two novel extended boost quasi-Z-source inverters are discussed. Lossless dynamic models of these topologies are presented and analyzed.

Vinnikov, Dmitri; Husev, Oleksandr; Roasto, Indrek

2011-01-01

226

Hybrid Voltage-Multipliers Based Switching Power Converters  

NASA Astrophysics Data System (ADS)

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.

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

227

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

NSDL National Science Digital Library

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.

2008-10-06

228

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

NSDL National Science Digital Library

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.

2008-10-06

229

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

NSDL National Science Digital Library

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.

2008-10-06

230

Holmes' statements at Buck vs. Bell, Paul LombardoSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

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.

2008-10-06

231

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

NSDL National Science Digital Library

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.

2008-10-06

232

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

NSDL National Science Digital Library

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.

2008-10-06

233

Stability analysis of input-series output-parallel connected buck rectifiers  

Microsoft Academic Search

AC voltages in the range of few kV have to be processed before being fed to traction motors. DC traction motors are normally designed for medium voltage and high current (1.2kV-1.5kV and 1200-1500A). Front-End Buck-Rectifiers are a viable solution for direct conversion of high ac voltage to low dc output voltage. However several buck-rectifier modules need to be connected in

Poonam Chaudhary; Ashish Agarwal; Parthasarathi Sensarma

2010-01-01

234

Topological Design and Modulation Strategy for Buck–Boost Three-Level Inverters  

Microsoft Academic Search

To date, designed topologies for DC-AC inversion with both voltage buck and boost capabilities are mainly focused on two-level circuitries with extensions to three-level possibilities left nearly unexplored. Contributing to this area of research, this paper presents the design of a number of viable buck-boost three-level inverters that can also support bidirectional power conversion. The proposed front-end circuitry is developed

Feng Gao; Poh Chiang Loh; Remus Teodorescu; Frede Blaabjerg; D. Mahinda Vilathgamuwa

2009-01-01

235

Single-stage converters for PV lighting systems with MPPT and energy backup  

Microsoft Academic Search

Single-stage converters (SSCs) are proposed for applications of photovoltaic powered lighting system (PPLS). The synchronous switch technique is employed to develop the SSCs which can fulfill maximum power point tracking (MPPT), battery charging, discharging, and lamp ballasting features. Several typical SSCs are discussed. One of the proposed SSCs, which is the integration of a buck-boost charger\\/discharger and a class-D series

Tsai-Fu Wu; Chien-Hsuan Chang; Yong-Jing Wu

1999-01-01

236

Single-stage converters for photovoltaic powered lighting systems with MPPT and charging features  

Microsoft Academic Search

This paper proposes single-stage power converters (SSCs) for application in photovoltaic powered lighting systems. The synchronous switch technique is employed to synthesize the SSCs which can fulfill maximum power point tracking, battery charging, discharging and lamp ballasting features. Several typical SSCs are discussed in the paper. One of the proposed SSCs, which is the integration of a buck-boost charger\\/discharger and

T.-F. Wu; C.-H. Chang; Z.-R. Liu; T.-H. Yu

1998-01-01

237

A fuzzy-logic-controlled single-stage converter for PV-powered lighting system applications  

Microsoft Academic Search

This paper presents a fuzzy-logic-controlled single-stage power converter (SSC) for photovoltaic (PV)-powered lighting system applications. The SSC is the integration of a bidirectional buck-boost charger\\/discharger and a class-D series resonant parallel loaded inverter. The designed fuzzy logic controller (FLC) can control both the charging and discharging current, and can improve its dynamic and steady-state performance. Furthermore, a maximum power point

Tsai-Fu Wu; Chien-Hsuan Chang; Yu-Hai Chen

2000-01-01

238

A novel compact soft-start circuit with internal circuitry for DC-DC converters  

Microsoft Academic Search

A novel internal soft-start circuit with simple topology for DC-DC buck converters is presented. It is implemented by controlling the output of error amplifier to make switch current limit increases in steps without using external capacitor, which reduces the component cost, saves board space and benefits for portable applications. This circuit is designed on the basis of Hynix 0.5 mum

Yuan Bing; Lai Xinquan; Ye Qiang; Jia Xinzhang

2007-01-01

239

GENERAL: Self-Stable Chaos Control of dc—dc Converter  

NASA Astrophysics Data System (ADS)

A new concept related to self-stable chaos control is first put forward, and its theoretical basis and realization are presented from the frequency-domain perspective. With a new analogous-circuit realization of this control its applications in the voltage-mode Buck converter is discussed. The harmonic-balance method is applied to determine the control range of the control parameter. The experiment results given in the last part confirm the validity of the proposed control method.

Lu, Wei-Guo; Zhou, Luo-Wei; Wu, Jun-Ke

2009-03-01

240

A new optimum topology switching dc-to-dc converter  

NASA Technical Reports Server (NTRS)

A novel switching dc-to-dc converter is presented, which has the same general conversion property (increase or decrease of the input dc voltage) as does the conventional buck-boost converter, and which offers through its new optimum topology higher efficiency, lower output voltage ripple, reduced EMI, smaller size and weight, and excellent dynamic response. One of its most significant advantages is that both input and output current are not pulsating but are continuous (essentially dc with small superimposed switching current ripple), thus resulting in a close approximation to the ideal physically nonrealizable dc-to-dc transformer. The converter retains the simplest possible structure with the minimum number of components which, when interconnected in its optimum topology, yield the maximum performance.

Cuk, S.; Middlebrook, R. D.

1977-01-01

241

Power converter  

NASA Technical Reports Server (NTRS)

A dc-to-dc converter employs four transistor switches in a bridge to chop dc power from a source, and a voltage multiplying diode rectifying ladder network to rectify and filter the chopped dc power for delivery to a load. The bridge switches are cross coupled in order for diagonally opposite pairs to turn on and off together using RC networks for the cross coupling to achieve the mode of operation of a free running multivibrator, and the diode rectifying ladder is configured to operate in a push-pull mode driven from opposite sides of the multivibrator outputs of the ridge switches. The four transistor switches provide a square-wave output voltage which as a peak-to-peak amplitude that is twice the input dc voltage, and is thus useful as a dc-to-ac inverter.

Black, J. M. (inventor)

1981-01-01

242

Robust DC/DC converter control for polymer electrolyte membrane fuel cell application  

NASA Astrophysics Data System (ADS)

This study investigates a robust controller in regulating the pulse width modulation (PWM) of a DC/DC converter for a polymer electrolyte membrane fuel cell (PEMFC) application. A significant variation in the output voltage of a PEMFC depends on the power requirement and prevents a PEMFC from directly connecting to a subsequent power bus. DC/DC converters are utilized to step-up or step-down voltage to match the subsequent power bus voltage. In this study, a full dynamic model, which includes a PEMFC and boost and buck DC/DC converters, is developed under MATLAB/Simulink environment for control. A robust PWM duty ratio control for the converters is designed using time delay control (TDC). This control enables state variables to accurately follow the dynamics of a reference model using time-delayed information of plant input and output information within a few sampling periods. To prove the superiority of the TDC performance, traditional proportional-integral control (PIC) and model predictive control (MPC) are designed and implemented, and the simulation results are compared. The efficacies of TDC for the PEMFC-fed PWM DC/DC converters are validated through experimental test results using a 100 W PEMFC as well as boost and buck DC/DC converters.

Wang, Ya-Xiong; Yu, Duck-Hyun; Chen, Shi-An; Kim, Young-Bae

2014-09-01

243

Convertible Stadium  

NASA Technical Reports Server (NTRS)

Air flotation technology used in NASA's Apollo program has found an interesting application in Hawaii's Aloha Stadium near Honolulu. The stadium's configuration can be changed, by moving entire 7,000-seat sections on a cushion of air, for best accommodation of spectators and participants at different types of events. In most stadiums, only a few hundred seats can be moved, by rolling sections on wheels or rails. At Aloha Stadium, 28,000 of the 50,000 seats can be repositioned for better spectator viewing and, additionally, for improved playing conditions. For example, a stadium designed primarily for football may compromise the baseball diamond by providing only a shallow outfield. Aloha's convertibility allows a full-size baseball field as well as optimum configurations for many other types of sports and special events. The photos show examples. The stadium owes its versatility to air flotation technology developed by General Motors. Its first large-scale application was movement of huge segments of the mammoth Saturn V moonbooster during assembly operations at Marshall Space Flight Center.

1978-01-01

244

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

NSDL National Science Digital Library

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.

2008-10-06

245

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

Microsoft Academic Search

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

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

2009-01-01

246

John N. Buck (1906-1983): did he practically establish clinical psychology in Virginia?  

PubMed

A posthumous biographical profile is presented of John N. Buck, an early clinical psychologist who gained national recognition for his diverse contributions to the field. In addition to developing the House-Tree-Person (H-T-P) Projective Technique and an array of other psychological inventories, he was instrumental in establishing clinical psychology in Virginia. Buck served on the first Examining Board for Certification of Clinical Psychologists in Virginia (and the nation) and was later its chairman. He published his research in peer-reviewed journals and presented guest lectures at respected universities. These professional achievements were quite remarkable in light of the fact that Buck was paraplegic and had no college degree and only scattered formal training in psychology. PMID:8315047

Rowe, F B; Crews, W D; Finger, F W

1993-05-01

247

Barberton drilling project - Buck Reef Chert core BARB3  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

248

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

NASA Astrophysics Data System (ADS)

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

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

2010-06-01

249

Implementing a Farmers' Market Incentive Program: Perspectives on the New York City Health Bucks Program  

PubMed Central

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.

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

2013-01-01

250

Current Source Converters in Discontinuous Conduction Modes of Operation  

NASA Astrophysics Data System (ADS)

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

Cuzner, Robert M.

251

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

NSDL National Science Digital Library

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

2008-10-06

252

Research on the Reconfigurable Implementation of Neural Network Controller Based on FPGA for DC-DC Converters  

Microsoft Academic Search

A neural network controller for DC\\/DC buck converters is proposed, and then the hardware implementation problem of the controller\\u000a based on FPGA is discussed in this paper. The neural network is trained using bp method. The reconfigurable feature is analyzed\\u000a and then three basic reconfigurable units are built based on SG \\/ Simulink. The simulation results show that the FPGA-based

Yanxia Shen; Tai Li; Zhicheng Ji

2009-01-01

253

Exact Linearization Nonlinear Neutral-Point Voltage Control for Single-Phase Three-Level NPC Converters  

Microsoft Academic Search

This letter proposes a new control scheme for the neutral-point (NP) balance in single-phase three-level NP-clamped converters. The control is addressed considering the plant under study, a nonlinear time-variant system. A quasi-exact linearization is applied allowing the application of classic control techniques. The described method is simple, general, and suitable for buck and boost topologies, as well as for inverter

Santiago Cobreces; Josep Bordonau; Joan Salaet; Emilio J. Bueno; Francisco J. Rodriguez

2009-01-01

254

Space-vector modulated PWM converters for photo-voltaic interface applications: analysis, power management and control issues  

Microsoft Academic Search

This paper presents new power management and control concepts for power converters that interface a photovoltaic (PV) system to an electric utility power system. The interface circuit is a space-vector modulated (SVM), high-frequency, 3?, PWM buck-type inverter. Decoupled control of DC voltage for peak power tracking, and the quadrature component of AC output current for reactive power flow control is

J. Rajagopalan; B. H. Cho

1995-01-01

255

Making the Most of Migrant Health Dollars: How Much Bang for the Buck?  

ERIC Educational Resources Information Center

The article presents a program planning model for getting the most "bang for the buck" out of migrant health services delivery in Colorado. Elements of the model offer promise as viable short-term solutions to complex care delivery problems, including overlapping manpower, inadequate hospital care linkage and information flow issues. (Author/NQ)

Gillespie, John J.; Barnett, Stephen E.

1978-01-01

256

Effect of cryoprotectants on certain seminal attributes and on the fertility of buck spermatozoa  

Microsoft Academic Search

Semen samples were obtained from 12 bucks (3 Beetal, 3 Black Bengal and 6 Beetal × Black Bengal) and 10 different extenders were constituted with varying concentrations of glycerol, DMSO, glycerol + DMSO and glycerol + lactose as the sperm cryoprotective agents. After the collection of semen samples, they were assessed for quality, diluted in different extenders after removal of

M. P. Singh; A. K. Sinha; B. K. Singh

1995-01-01

257

Optimized diffusion of buck semen for saving genetic variability in selected dairy goat populations  

PubMed Central

Background Current research on quantitative genetics has provided efficient guidelines for the sustainable management of selected populations: genetic gain is maximized while the loss of genetic diversity is maintained at a reasonable rate. However, actual selection schemes are complex, especially for large domestic species, and they have to take into account many operational constraints. This paper deals with the actual selection of dairy goats where the challenge is to optimize diffusion of buck semen on the field. Three objectives are considered simultaneously: i) natural service buck replacement (NSR); ii) goat replacement (GR); iii) semen distribution of young bucks to be progeny-tested. An appropriate optimization method is developed, which involves five analytical steps. Solutions are obtained by simulated annealing and the corresponding algorithms are presented in detail. Results The whole procedure was tested on two French goat populations (Alpine and Saanen breeds) and the results presented in the abstract were based on the average of the two breeds. The procedure induced an immediate acceleration of genetic gain in comparison with the current annual genetic gain (0.15 genetic standard deviation unit), as shown by two facts. First, the genetic level of replacement natural service (NS) bucks was predicted, 1.5 years ahead at the moment of reproduction, to be equivalent to that of the progeny-tested bucks in service, born from the current breeding scheme. Second, the genetic level of replacement goats was much higher than that of their dams (0.86 unit), which represented 6 years of selection, although dams were only 3 years older than their replacement daughters. This improved genetic gain could be achieved while decreasing inbreeding coefficients substantially. Inbreeding coefficients (%) of NS bucks was lower than that of the progeny-tested bucks (-0.17). Goats were also less inbred than their dams (-0.67). Conclusions It was possible to account for complex operational constraints while developing goat selection schemes, both efficient and sustainable. Therefore, the recommended selection and mating decisions might receive attention from goat breeders using both AI and NS.

2011-01-01

258

Chaos, bifurcation and intermittent phenomena in DC-DC converters under resonant parametric perturbation  

NASA Astrophysics Data System (ADS)

DC-DC converters act as a black box to study various bifurcations. In the present study, the influence of external periodic interference signal in the input of DC-DC voltage-mode controlled buck converter has been considered. It is found that the presence of sinusoidal or saw-tooth interference signal whose frequency is comparable with the switching frequency of the converter or its rational multiples manifests as remerging chaotic band attractors (or Feigenbaum trees) and intermittent chaos. However, the presence of sinusoidal interference signal having irrational frequency ratios with the switching frequency of the converter leads to quasi-periodic route to chaos. The study was carried out both theoretically and experimentally.

Deivasundari, P.; Geetha, R.; Uma, G.; Murali, K.

2013-07-01

259

Research on control type soft switching converters  

Microsoft Academic Search

Paper clarifies the definition of control type soft switching and presents five characteristics for control type soft switching topologies. The theory of five characteristics is verified in the existing control type soft switching topologies, and a series of new control type soft switching topologies, such as buck, boost, buck-boost, cuk, zeta, sepic, flyback, and forward are constructed. A 200 kHz

Yilei Gu; Lijun Hang; Shijie Chen; Yu Du; Zhengyu Lu; Zhaoming Qian

2004-01-01

260

Proposed Interstate Energy Company Pipeline to be Located in the Pennsylvania Counties of Bucks, Chester, Delaware, Montgomery and Northampton.  

National Technical Information Service (NTIS)

The project proposes to construct, operate, and maintain a buried, insulated fuel-oil pipeline originating at a marine docking facility in Marcus Hook, Pennsylvania and routed through Delaware, Chester, Montgomery, Bucks and Northampton Counties, to a nor...

1974-01-01

261

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

NSDL National Science Digital Library

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.

2008-10-06

262

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

NSDL National Science Digital Library

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.

2008-10-06

263

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

NSDL National Science Digital Library

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.

2008-10-06

264

Feasibility study for convertible engine torque converter  

NASA Technical Reports Server (NTRS)

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.

1985-01-01

265

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

Microsoft Academic Search

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

Lari Nousiainen; Teuvo Suntio

2011-01-01

266

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

NASA Astrophysics Data System (ADS)

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

Alekou, A.; Pasternak, J.

2012-08-01

267

Magnetic Field Reduction in Photomultipliers with the use of Bucking Coil  

NASA Astrophysics Data System (ADS)

Three segmented aerogel Cerenkov detectors are employed in the Jefferson Lab High Resolution Kaon Spectrometer (HKS). Cerenkov light is detected with 5'' PMTs. At the detector location a stray field from the magnet of ˜5 gauss significantly reduces the photoelectron collection efficiency of the PMTs, despite the use of magnetic shielding. Therefore, we propose to compensate the stray field with bucking coils. In a test setup, a Helmholtz Coil was used to generate external magnetic fields up to 15 gauss. In order to counteract this B field 20 turns of bucking coil (gauge: 12 AWG) were mounted around the cathode sides of the PMT. A recovery of roughly 87.5% was determined for an external B field of 5 Gauss. The experimental procedure and results of both this and new studies will be presented in detail.

Mesa, Dalgis; Reinhold, Joerg

2007-04-01

268

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

NSDL National Science Digital Library

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.

2008-10-06

269

Boost-buck inverter variable structure control for grid-connected photovoltaic systems with sensorless MPPT  

Microsoft Academic Search

The present work describes the analysis, modeling and control of a transformerless boost-buck power inverter used as a DC-AC power conditioning stage for grid-connected photovoltaic (PV) systems. The power conditioning system's control scheme includes a variable structure controller to assure output unity power factor and a sensorless maximum power point tracking (MPPT) algorithm to optimize the PV energy extraction. To

Carlos Meza; Domingo Biel; Juan Negroni; Francesc Guinjoan

2005-01-01

270

Lifetime mating success, sexual selection and life history of fallow bucks ( Dama dama )  

Microsoft Academic Search

We used data from a long-term study (15 years) of fallow deer to report for the first time the lifetime mating success, overall\\u000a variance in lifetime mating success, and age-specific mortality levels of males. Fallow bucks that gain matings have higher\\u000a social dominance rank, higher rates of fighting, and invest more in vocal display during the breeding season than unsuccessful

Alan G. McElligott; Thomas J. Hayden

2000-01-01

271

Effect of nutrition on lipid production and composition of Cashmere buck fleece  

Microsoft Academic Search

This study examined the lipid content and fatty acid composition of fleece samples collected in April, which is during the breeding period, from different body regions of Cashmere bucks fed ad libitum diets of high (pelleted lucerne, Medicago sativa, 8.3 mJ kg?1 ME, 17.6% CP) and low (coarsely hammermilled pangola grass, Digitaria decumbens, 6.6 mJ kg?1 ME, 6.9% CP) quality.

G. C. Hillbrick; D. J. Tucker

1996-01-01

272

Modeling and Robust Control of a Three-Phase Buck+Boost PWM Rectifier (VRX-4)  

Microsoft Academic Search

The modeling and control of a three-phase three-switch buck-type rectifier system with integrated boost output stage (voltage range extended 4-switch rectifier) is analyzed in this paper. A cascaded multiloop control structure is presented that has the following features: constant output voltage for a wide input voltage range and stepwise changes of load; sinusoidal input currents in phase with the mains

Thomas Nussbaumer; Guanghai Gong; Marcelo Lobo Heldwein; Johann W. Kolar

2008-01-01

273

Influence of input supply voltage unbalances on the performance of AC\\/DC buck rectifiers  

Microsoft Academic Search

This paper deals with the effects of input supply voltage unbalance on the steady-state, small-signal dynamic and transient performance of AC\\/DC buck rectifiers with modulation magnitude and phase angle control. Operations with balanced and unbalanced input supply voltage source are compared. A comprehensive analysis based on the complex d-q-n synchronous reference frame transformation and harmonic balance technique shows that third

Olorunfemi Ojo; Ishwar Bhat

1994-01-01

274

Double-loop control and stability analysis based on three-phase Buck-Boost inverter  

Microsoft Academic Search

To develop and apply renewable energy, one of the key technologies is that a kind of inverter outputting high quality sinusoid signals to power network is required. This paper proposed a three-phase buck-boost inverter, which can generate a three-phase ac output voltage larger than the dc input one. Its basic configuration is introduced, and the system stability of open-loop is

Zhu Jianlin; Xiang Lidan; Liu Shasha

2008-01-01

275

Interpreted reflection seismic events near the North Central Oil Corporation Well, Newark Basin, Bucks County, Pennsylvania  

Microsoft Academic Search

In 1985, North Central Oil Corporation drilled a 10,500-ft well in Bucks County, Pennsylvania, to test for oil and gas in Triassic-Jurassic strata of the Newark Group in the Newark basin. The hole was located about 5 mi southeast of the border fault on the crest of the Revere anticline, a transverse structure that plunges northwestward toward the border fault.

R. T. Ryder; J. J. Miller; J. A. Grow; N. M. Ratcliffe

1993-01-01

276

On a new method of tipping buck gauge calibration at HMS  

NASA Astrophysics Data System (ADS)

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

Morvai, Krisztián; Nagy, Zoltán

2013-04-01

277

Pathological conditions associated with the male reproductive tract of the sahel bucks.  

PubMed

The study of pathological conditions of the male reproductive system is paramount to understanding reproductive inefficiency in the Sahel goat. In this study, 1048 Sahel bucks presented for slaughter at the Maiduguri metropolitan abattoir were evaluated for the presence of various pathological abnormalities of the reproductive system. A total incidence of 15.08% was recorded for various pathological conditions, with testicular, penile, and scrotal conditions having incidences of 7.82%, 4.80 and 2.50%, respectively. Bilateral testicular hypoplasia and atrophy and unilateral cryptorchidism accounted for incidences of 4.10%, 2.38%, and 1.24%, respectively, while paraphimosis and scrotal laceration had incidences of 1.72% and 1.05%, respectively. Age specific incidence of pathological conditions were not significant (P > 0.05) between bucks aged <1-1.5 and 2-2.5 years. However, bucks aged 3-3.5 year a had lower (P < 0.05) incidence of pathological conditions than other age groups. Histopathological evidence of inflammation, degeneration, and atrophy was observed in the testes, while inflammatory changes were observed in the prepuce. PMID:24790768

Abba, Yusuf; Simon, Suleiman; Idris Gambo, Halima; Onyebuchi Igbokwe, Ikechukwu; Iliyasu, Yusuf

2014-01-01

278

Pathological Conditions Associated with the Male Reproductive Tract of the Sahel Bucks  

PubMed Central

The study of pathological conditions of the male reproductive system is paramount to understanding reproductive inefficiency in the Sahel goat. In this study, 1048 Sahel bucks presented for slaughter at the Maiduguri metropolitan abattoir were evaluated for the presence of various pathological abnormalities of the reproductive system. A total incidence of 15.08% was recorded for various pathological conditions, with testicular, penile, and scrotal conditions having incidences of 7.82%, 4.80 and 2.50%, respectively. Bilateral testicular hypoplasia and atrophy and unilateral cryptorchidism accounted for incidences of 4.10%, 2.38%, and 1.24%, respectively, while paraphimosis and scrotal laceration had incidences of 1.72% and 1.05%, respectively. Age specific incidence of pathological conditions were not significant (P > 0.05) between bucks aged <1–1.5 and 2–2.5 years. However, bucks aged 3–3.5 year a had lower (P < 0.05) incidence of pathological conditions than other age groups. Histopathological evidence of inflammation, degeneration, and atrophy was observed in the testes, while inflammatory changes were observed in the prepuce.

Simon, Suleiman; Idris Gambo, Halima; Onyebuchi Igbokwe, Ikechukwu; Iliyasu, Yusuf

2014-01-01

279

Influence of seasons, extenders, slow and rapid freezing on seminal characters in Korean native bucks.  

PubMed

The success of AI technology is based on both semen quality and freezing process. In order to establish the semen freezing techniques in Korean native bucks, factors affecting the success were evaluated in the present study. Semen collected by electro-ejaculation from bucks during four distinct seasons was evaluated for semen volume and pH, sperm motility and survivability. The semen volume, concentration and total cell were higher in spring, summer and less in winter. Yet, there were no seasonal differences in the proportional data of live sperm, motility score and pH of semen among seasons. The percentage of live sperm after thawing was found to increase with increased concentration of lactose in Tris-Egg yolk-glycerol (TY-G), being highest in TY-G supplemented with 180 mm lactose (TYL180-G), but did not differ between TY-G and TYL120-G. Sperm motility was enhanced by employing 2.0 h equilibration time with rapid freezing method. In conclusion, semen could be frozen with high success rates for further use of AI in breeding techniques and to preserve the Korean native bucks. PMID:16420329

Choe, Chang-Yong; Kim, Jung-Gon; Cho, Sang-Rae; Son, Dong-Soo; Kim, Young-Keun; Balasubramanian, S; Choe, Sang-Yong; Rho, Gyu-Jin

2006-02-01

280

Modeling of multilevel converters  

Microsoft Academic Search

In this paper, the imbricated cells multilevel converters are studied and modeled from a control viewpoint. These converters make use of several switches connected in a series, which allows using switches with reduced voltage ratings; these low voltage switches have lower conduction losses and can switch at higher frequency. In addition to this feature common to all converters using series

T. A. Meynard; M. Fadel; N. Aouda

1997-01-01

281

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

PubMed

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

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

2014-05-01

282

Rotorcraft convertible engine study  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

283

Analysis of transistor and snubber turn-off dynamics in high-frequency high-voltage high-power converters  

NASA Technical Reports Server (NTRS)

Dc to dc converters which operate reliably and efficiently at switching frequencies high enough to effect substantial reductions in the size and weight of converter energy storage elements are studied. A two winding current or voltage stepup (buck boost) dc-to-dc converter power stage submodule designed to operate in the 2.5-kW range, with an input voltage range of 110 to 180 V dc, and an output voltage of 250 V dc is emphasized. In order to assess the limitations of present day component and circuit technologies, a design goal switching frequency of 10 kHz was maintained. The converter design requirements represent a unique combination of high frequency, high voltage, and high power operation. The turn off dynamics of the primary circuit power switching transistor and its associated turn off snubber circuitry are investigated.

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

1982-01-01

284

Interleaved power converter  

DOEpatents

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.

Zhu, Lizhi (Canton, MI)

2007-11-13

285

Convertible Exchangeable Preferred Stock  

Microsoft Academic Search

Convertible exchangeable preferred stock includes an option for the issuer to exchange the preferred for convertible bonds with identical pre-tax cash flows and conversion terms. In other respects this innovative corporate security is identical to traditional convertible preferred stock. The exchange feature provides the issuer with a potentially valuable option to swap a non-tax-deductible expense for a tax-deductible one. The

Arnold R. Cowan

1996-01-01

286

GraphicConverter  

NSDL National Science Digital Library

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

287

Predicted sex ratio of juvenile Hawksbill Seaturtles inhabiting Buck Island Reef national monument, U.S. Virgin Islands  

USGS Publications Warehouse

Hawksbill Seaturtles have temperature-dependent sex determination. As such, the resulting sex ratios are of conservational and ecological significance. Buck Island Reef is an interesting location for sex ratio studies since it represents a natural and unexploited foraging ground for hawksbills in the Caribbean. To examine sex ratios, blood samples were obtained from juvenile Hawksbill Seaturtles captured on Buck Island Reef over a four-year period. We used a radioimmunoassay to determine testosterone levels in those samples and compared those values to testosterone levels of juvenile hawksbills from the Caribbean whose sex has been verified by laparoscopy. The results of this study reveal a significantly female-biased sex ratio (approximately 80% female) occurs in this juvenile aggregation inhabiting Buck Island Reef.

Geis, A.; Wibbels, T.; Phillips, B.; Hillis-Starr, Z.; Meylan, A.; Meylan, P.; Diez, C.; Van Dam, R.

2003-01-01

288

Bucking coil implementation on PMT for active canceling of magnetic field  

NASA Astrophysics Data System (ADS)

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.

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

289

Single-Switch Snubber Energy Recovery Bridge Leg for Buck Rectifier Applications  

NASA Astrophysics Data System (ADS)

Single-switch bridge leg with a snubber energy recovery feature is studied for buck rectifier applications. To recover the snubber energy, two snubber capacitors are arranged across an active power device. An example of a single-phase rectifier applying a proposed bridge leg is implemented to investigate the operation. The experimental results under the sinusoidal pulse-width modulation confirm that the rectifier can recover the snubber energy and the input current is almost wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu

290

Bucking Coil Implementation on PMT for Active Cancelling of Magnetic Field  

SciTech Connect

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.

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

291

Parametric energy converter  

Microsoft Academic Search

A method and apparatus for converting thermal energy into mechanical energy by parametric pumping of rotary inertia. In a preferred embodiment, a modified tesla turbine rotor is positioned within a rotary boiler along its axis of rotation. An external heat source, such as solar radiation, is directed onto the outer casing of the boiler to convert the liquid to steam.

Johnson

1981-01-01

292

The microminiature thermionic converter  

Microsoft Academic Search

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

Donald Bryan King

2000-01-01

293

Variable Geometry Torque Converter.  

National Technical Information Service (NTIS)

Program objective was to design and evaluate a breadboard variable reactor system using the B-1 secondary power system torque converter. Results of the evaluation indicate that a variable reactor can be used in a small, high-speed torque converter to cont...

K. W. Benn G. L. Perrone

1978-01-01

294

Public health assessment for Dublin Water Supply, Dublin, Bucks County, Pennsylvania, Region 3. Cerclis No. PAD981740004. Preliminary report  

SciTech Connect

The Dublin TCE Site (formerly the Dublin Water Supply Site) is a National Priorities List Update 10 site located at 120 Mill Street in Dublin Borough, Bucks County, Pennsylvania. During a routine drinking water survey in 1986, the Bucks County Health Department discovered elevated levels of trichloroethylene (TCE) in tap water samples obtained in the Dublin Borough area. The site posed a public health hazard prior to treatment of water supplies. Currently, the site is an indeterminate health hazard because the moving groundwater plume is still under study.

Not Available

1994-03-21

295

Cascaded resonant bridge converters  

NASA Technical Reports Server (NTRS)

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

Stuart, Thomas A. (Inventor)

1989-01-01

296

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

297

Microminiature thermionic converters  

DOEpatents

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.

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

2001-09-25

298

Advanced thermionic converter development  

NASA Technical Reports Server (NTRS)

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 functions of less than 1.2 eV. Five techniques of oxygen addition to thermionic converters are discussed. Vapor deposited tungsten oxide collector diodes and the reflux converter are considered.

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

1976-01-01

299

Fluorescent radiation converter  

NASA Technical Reports Server (NTRS)

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

Viehmann, W.

1980-01-01

300

Wirephoto Standards Converter.  

National Technical Information Service (NTIS)

A standards converter that translates simultaneously between the United States and European wirephoto networks has been developed. Items of noncompatibility include picture duration, lines per minute, lines per inch, and scanning direction. The system ope...

D. E. Troxel W. F. Schreiber C. L. Seitz

1968-01-01

301

Multilevel converters -- A new breed of power converters.  

National Technical Information Service (NTIS)

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....

J. S. Lai F. Z. Peng

1995-01-01

302

PDF to HTML Converter  

NSDL National Science Digital Library

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.

2010-01-01

303

Thermionic photovoltaic energy converter  

NASA Technical Reports Server (NTRS)

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

Chubb, D. L. (inventor)

1985-01-01

304

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

Microsoft Academic Search

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

A. I. Ukanwoko; J. A. Ibeawuchi

2009-01-01

305

Three-phase series-buck rectifier with split DC-bus based on the Scott transformer  

Microsoft Academic Search

In this paper, a new unity power factor isolated three-phase buck rectifier is presented. Based on the Scott transformer, this rectifier is simple and it has the capability to obtain low output voltage. Besides, it protects against short circuit and it needs no auxiliary circuit for inrush current. Using only two active switches, it is able to generate symmetrical currents

Alceu André Badin; Ivo Barbi

2008-01-01

306

X-ray converter  

US Patent & Trademark Office Database

An X-RAY CONVERTER having a light-proof housing with an X-ray-transparent wall behind which there are fastened an X-ray-to-optical converter, a filter of residual X-radiation, an objective lenses unit, and a photodetector containing at least two optoelectronic converters with partly overlapping fields of view and separated electrical outputs for connection to a system for processing of fragmentary video signals and generating an integral output video signal. For improving the efficiency of suppression of internal interferences in optical channels and the operating reliability, within the housing, parallel to the X-ray-to-optical converter, there is rigidly fastened an additional light- and X-ray-opaque partition with through-holes which in the number and placement correspond to objective lenses and optoelectronic converters and are blocked by washers of the filter of residual X-radiation, and ahead of the washers there are installed blinds, length A of each of which and distance D from the front surface of the X-ray-to-optical converter to the plane of front end faces of objective lenses are related by the ratio A/D=(0.50 . . . 0.95).

2009-02-24

307

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

PubMed Central

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.

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

2013-01-01

308

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

NASA Astrophysics Data System (ADS)

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.

Suskis, P.; Rankis, I.

2012-01-01

309

Multilevel converters-a new breed of power converters  

Microsoft Academic Search

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

Jih-Sheng Lail; Fang Zheng Peng

1995-01-01

310

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

311

Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector  

NASA Astrophysics Data System (ADS)

Jefferson Lab Experiment E05-115 will perform a spectroscopic study of lambda hypernuclei for a wide mass region using the (e,e'K^+) reaction. Accurate detection of coincident kaons and electrons guarantees that a lambda hyperon has been produced within the nucleus. The High Resolution Kaon Spectrometer, whose instrumentation is composed of, among other devices, a water Cerenkov detector (WC), will be employed towards this end. The detector uses a series of photomultiplier tubes (PMT) to generate signals associated with particular events. In the fringe magnetic field of the spectrometer magnet, the PMTs' detection efficiency degrades significantly. Magnetic fields of equal strength and opposite orientation to the external field are created by applying current to bucking coils (BC) placed around the individual PMT. Data indicates a relationship between SPE emission rates, and collection efficiency distributions. Upon being placed in Hall C, this relationship has been used to set the appropriate current for each BC.

Maxwell, Victor; Reinhold, Joerg

2009-11-01

312

Vector generator scan converter  

DOEpatents

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.

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

1988-02-05

313

Analog to Digital Converter.  

National Technical Information Service (NTIS)

A device for converting a signal voltage into a multibit digital word that defines that voltage magnitude and polarity. The input voltage V to be digitized is used to control the frequency of a voltage controlled oscillator, whose output is defined to be ...

B. L. Lewis

1981-01-01

314

Heat flux converter  

Microsoft Academic Search

(usually by means of glue or putty). The operation of such a converter is based upon measurement of the entire quantity of heat which enters it from the start of the process. Strict fulfillment of the latter condition is guaranteed by a choice of thickness of the calorimeter such that its inner surface is heated just so much during the

B. I. Bakum; L. V. Novikov; Yu. V. Yakhlakov

1968-01-01

315

How to Convert Temperatures  

NSDL National Science Digital Library

This elementary school classroom activity has students measure water temperature, use formulas to convert between Fahrenheit, Celsius, and Kelvin, and use a conversion tool to check their answers between the three systems. It is part of the Atmospheric Visualization Collection (AVC), which focuses on data from the Atmospheric Radiation Measurement (ARM) program.

2003-05-09

316

Fractional Watt AMTEC Converter  

NASA Astrophysics Data System (ADS)

We report here the long term performance of a small, multi-tube AMTEC converter. This converter was designed to operate and produce approximately 12 watt of electrical output from a small, 4 to 6 watt radioisotope heat source for remote power applications. It was built and put on test in 1999 using electrical heaters as stand-ins for the radioisotope capsule. Since that time it has accumulated more than 5 years of run time at an input heater temperature of 700 °C, with numerous thermal cycles to ambient that were generally related to grid power failures or physical moves of the test apparatus. The power output has remained, with variations due to orientation changes and minor variations due to small temperature changes, essentially constant at 0.40 W to 0.60 W over the test period and operation is ongoing. The converter casing and mechanical structure was fabricated from 316 SS and the electrodes are sputtered titanium nitride films. Separate static tests of a multilayer insulation package suitable for use with the converter showed the capability to reach 700 °C with a thermal input of < 4 watts.

Hunt, T. K.; Rasmussen, J. R.

2006-01-01

317

Ocean wave energy converter  

Microsoft Academic Search

A device for converting the energy of ocean waves into electricity, comprises a buoyant body that floats on the surface of the water and rises and falls with the waves. Fixedly secured to the buoyant body at a depth in the region of still water not affected by the waves, is a bucket wheel or bucket chain which will accordingly

1982-01-01

318

Ocean wave energy converter  

Microsoft Academic Search

This patent describes apparatus for converting the energy of wave motion on the surface of a body of water to electricity comprising: lower structural support means approximately forming edge elements of an equilateral triangle; lower tube receptacles connected to the lower structural support means approximately forming vertex elements of an equilateral triangle; tubular members having upper and lower portions positioned

1987-01-01

319

Converting industrial boilers  

Microsoft Academic Search

Based on the limitations of retrofit applications, a summary is presented of means by which existing oil or gas fired boilers can be converted to coal utilization. Boiler capacity is discussed as well as space limitations, particulate emissions, ash and cinder formation, air pollution, and effectiveness. Specifically, the following modes of firing are discussed: (1) spreader stoker firing; (2) pulverized

D. F. Dunphy; V. S. Ramapriya

1981-01-01

320

Converting Bookmobiles to Paperbacks  

ERIC Educational Resources Information Center

The Oklahoma County Libraries System in Oklahoma City converted its five bookmobiles from hardbound to paperbound materials in 1975. The conversion has been a notable success, proving popular with patrons and proving low cost and efficient for the library system. (Author)

Little, Paul

1976-01-01

321

Digitise this: converting content  

Microsoft Academic Search

This paper describes and illustrates the new processes that CAVAL is using to convert content into digital form. The research and development process began with the purchase of a Kirtas 2400 RA Book Digitising device in 2008. This Kirtas with its page-turning technology now underpins the provision of high quality digitisation services for books and bound volumes. Issues discussed include

Cathie Jilovsky; George Panagiotidis

322

Snubber-Assisted Zero-Voltage and Zero-Current Transition Bilateral Buck and Boost Chopper for EV Drive Application and Test Evaluation at 25 kW  

Microsoft Academic Search

A new high-efficiency and high-power bilateral buck and boost chopper circuit for the electric-vehicle drive application is presented. The operation principle of snubber-assisted zero-voltage and zero-current transition (SAZZ) topology was applied, and a new SAZZ bilateral buck-boost chopper circuit (SAZZ-1) was created by combining two basic SAZZ circuit types. A 50-kHz 25-kW SAZZ-1 was fabricated and tested. An efficiency of

Yukinori Tsuruta; Yoshihiro Ito; Atsuo Kawamura

2009-01-01

323

Proposal of Bilateral Buck and Boost Chopper Circuit SAZZ-1 for EV Drive Application and the Test Evaluation at 25kW  

Microsoft Academic Search

A new high efficiency and high power bilateral boost and buck chopper circuit for the electric vehicle (EV) drive application is presented. The operation principle of SAZZ (snubber assisted zero voltage and zero current transition) topology was applied and a new SAZZ bilateral buck-boost chopper circuit (SAZZ-1) was created by combining two basic SAZZ circuit types. A 50 kHz-25 kW

Yukinori Tsuruta; Yoshihiro Ito; M. Bando; A. Kawamura

2006-01-01

324

Liquid metal thermal electric converter  

DOEpatents

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.

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

1989-01-01

325

Parametric energy converter  

SciTech Connect

A method and apparatus for converting thermal energy into mechanical energy by parametric pumping of rotary inertia. In a preferred embodiment, a modified tesla turbine rotor is positioned within a rotary boiler along its axis of rotation. An external heat source, such as solar radiation, is directed onto the outer casing of the boiler to convert the liquid to steam. As the steam spirals inwardly toward the discs of the rotor, the moment of inertia of the mass of steam is reduced to thereby substantially increase its kinetic energy. The laminar flow of steam between the discs of the rotor transfers the increased kinetic energy to the rotor which can be coupled out through an output shaft to perform mechanical work. A portion of the mechanical output can be fed back to maintain rotation of the boiler.

Johnson, R.N.

1981-10-20

326

A current controlled near unity power factor three-phase PWM buck rectifier without passive damping requirements  

Microsoft Academic Search

Three-phase current source PWM rectifier (also known as three-phase buck rectifier) is often used as the front-end in utility interfaced systems. An input LC filter is required to suppress the current harmonics injected into AC mains. The input filter affects the input displacement factor (IDF) of the system, which varies with the rectifier operating point and may result in unacceptable

Navid R. Zargari; D. Raonic

1995-01-01

327

Control-oriented modeling and robust control of a three-phase buck+boost PWM rectifier (VRX-4)  

Microsoft Academic Search

The modeling and control of a three-phase, three-switch buck-type rectifier system with integrated boost output stage (VRX-4) is analyzed in this paper. A cascaded multi-loop control structure is presented that has the following features: constant output voltage for a wide input voltage range and step-wise changes of load; sinusoidal input currents in phase with the mains voltages that also remain

T. Nussbaumer; G. Gong; M. L. Heldwein; J. W. Kolar

2005-01-01

328

Space-vector ?? modulator and sliding mode control of the three-phase buck type rectifier with freewheeling diode  

Microsoft Academic Search

This paper presents a vector based sliding mode control method for three-phase buck type three-phase rectifiers with freewheeling diode. This fast and robust technique uses sliding mode to generate ?? space-vector modulation, which forces the input line currents to track a suitable sinusoidal reference. A near unity power factor operation of the rectifier is obtained using a sinusoidal reference in

V. Ferngo Pires; J. Fernando Silva; G. D. Marques

2002-01-01

329

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

USGS Publications Warehouse

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

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

1994-01-01

330

Purplemath: Cancelling / Converting Units  

NSDL National Science Digital Library

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.

Stapel, Elizabeth

331

Digital to synchro converter  

NASA Technical Reports Server (NTRS)

A digital-to-synchro converter is provided where a binary input code specifies a desired shaft angle and where an resolver type position transducer is employed with additional circuitry to generate a shaft position error signal indicative of the angular difference between the desired shaft angle and the actual shaft angle. The additional circuitry corrects for known and calculated errors in the shaft position detection process and equipment.

Predina, Joseph P. (Inventor)

1989-01-01

332

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

333

Multilevel converters -- A new breed of power converters  

SciTech Connect

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.

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

1996-05-01

334

Sperm chromatin integrity of bucks transgenic for the WAP bGH gene.  

PubMed

The aim of the study was to compare sperm chromatin structure of transgenic and non-transgenic rabbits. In addition, the effect of chromatin structure on semen fertility was determined. Twenty male rabbits transgenic (TG) for WAP bGH gene (Edison Biotechnology Institute Ohio University, USA) and nine non-transgenic (NTG) males were used. Both TG and NTG rabbits were 13-18 months old. Semen was collected at 1-week intervals and 3-7 ejaculates from each rabbit were examined in total. Sperm chromatin abnormalities were measured flow cytometrically according to the Sperm Chromatin Structure Assay method: after chromatin denaturation by low pH, sperm cells were stained with metachromatic fluorochrome acridine orange. Spermatozoa with abnormal chromatin structure and, subsequently, higher degree of denaturation, showed a shift in red fluorescence. Two different methods of semen fertility estimation were used: (1) for TG rabbits, AI of superovulated does and calculation of percentages of fertilised eggs and embryos developing in vitro to the blastocyst stage; (2) for NTG rabbits, AI of non-stimulated does and calculation of percentages of pregnant does and mean litter sizes. The mean value of COMPalpha(t) was 3.71 for TG rabbits and 2.89 for NTG rabbits (no significant difference, t-test). The mean values of S.D.alpha(t) for the TG and NTG rabbits were 10.94 and 10.40 (no significant difference, t-test), respectively. There were no significant correlations between sperm chromatin structure of TG males and the percentages of fertilised eggs or embryos developing to the blastocyst stage. A statistically significant correlation (-0.68, P<0.05) was found between S.D.alpha(t) of NTG males and percentages of pregnant does. The results showed chromatin stability was not different for sperm obtained from TG versus NTG bucks. The presence of WAP bGH gene construct in the genome of transgenic rabbits did not cause any spermatogenesis process disturbances leading to the production of spermatozoa with damaged chromatin structure. This suggests that the mere presence of the introduced gene construct does not lead to any abnormalities in DNA and chromatin proteins interaction. The possible chromatin damages in transgenic animals should be attributed to the activity of the introduced gene. The relationships between chromatin structure and fertility are only significant for sperm from NTG bucks. PMID:11078972

Gogol, P; Bochenek, M; Smorag, Z

2000-12-01

335

Growth performance and nutrient utilization in black Bengal bucks (Capra hircus) supplemented with graded doses of chromium as chromium chloride hexahydrate.  

PubMed

Black Bengal bucks (Capra hircus) were supplemented with 0, 0.2 or 0.4 mg elemental chromium (Cr) as chromium chloride hexahydrate per day for 70 days. Intake of dry matter (p<0.001), crude protein (p<0.001) and neutral detergent fiber (p<0.01) increased due to Cr supplementation. The apparent total tract digestibility of dry matter (p<0.01), organic matter (p<0.05), crude protein (p<0.001) and acid detergent fiber (p<0.01) improved and the total body weight gain and the live weight gain to feed intake ratio also increased (p<0.001) due to supplemental Cr feeding. The intake and apparent absorption (p<0.001) of Cr was enhanced due to its supplementation. The intake of copper, zinc, manganese and iron was also more (p<0.001) in the Cr supplemented bucks. As supplementation progressed, plasma glucose concentration was elevated particularly in 0.4 mg Cr supplemented bucks and a significant day x dose interaction effect (p<0.001) with this parameter. The activity of plasma alkaline phosphatase increased (p<0.001) and that of glutamate pyruvate transaminase in plasma decreased (p<0.01) in the Cr supplemented bucks. Supplemental Cr had minimal (p>0.05) effect on the plasma half life (k) and clearance rate of glucose (T1/2) during an intravenous glucose tolerance test. Area under the response curve from 0 to 180 minutes after glucose loading was lower (p<0.001) in the control group of bucks. The study revealed that Cr supplementation might promote growth and nutrient utilization in black Bengal bucks. However, little difference between the 0.2 and 0.4 mg Cr supplemented bucks suggested limited benefit of increasing the level of supplementation beyond 0.2 mg per day under the normal management regimes. PMID:15785121

Paul, Tarun K; Haldar, Sudipto; Ghosh, Tapan K

2005-03-01

336

Cycloidal Wave Energy Converter  

SciTech Connect

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.

Stefan G. Siegel, Ph.D.

2012-11-30

337

The convertible flywheel  

NASA Astrophysics Data System (ADS)

The design and testing of a new twin-disk composite flywheel is described. It is the first flywheel to store 2 kW-hr of energy and the first to successfully combine the advantages of composite materials with metal hubs, thus providing a system-ready flywheel with high energy storage and high torque capabilities. The use of flywheels in space for energy storage in satellites and space stations is examined. The convertibility of the present flywheel to provide the next generation Annular Momentum Control Device or Annular Suspension and Pointing System is discussed.

Ginsburg, B. R.

338

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.

1998-01-01

339

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.

1997-01-01

340

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

SciTech Connect

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

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

2012-12-21

341

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

USGS Publications Warehouse

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.

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

342

Solution of the Schrödinger equation containing a Perey-Buck nonlocality  

NASA Astrophysics Data System (ADS)

The solution of a radial Schrödinger equation for ?(r) containing a nonlocal potential of the form ?K(r,r')?(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 ? in a set of Chebyshev polynomials, and solving the matrix equation for the expansion coefficients numerically. An accuracy of between 1:10-5 and 1:10-11 is obtained, depending on the number of polynomials employed. The second method consists in expanding ? into a set of NS Sturmian functions of positive energy, supplemented by an iteration procedure. For NS=15 an accuracy of 1:10-4 is obtained without iterations. After one iteration the accuracy is increased to 1:10-6. Both methods are applicable to a general nonlocality K. The spectral method is less complex (requires less computing time) than the Sturmian method, but the latter can be very useful for certain applications.

Rawitscher, George H.

2012-07-01

343

Commissioning and Calibrating Bucking Coil System for HKS Water Cerenkov Detector  

NASA Astrophysics Data System (ADS)

Experiment E05-115, in Hall C at Jefferson Lab (JLab), will perform a spectroscopic study of lambda hypernuclei for a wide mass region using the (e, e' K^+) reaction. Accurate detection of coincident kaons and electrons guarantees that a lambda hyperon has been produced within the nucleus. The High Resolution Kaon Spectrometer, whose instrumentation is composed of, among other devices, a water Cerenkov detector (WC), will be employed towards this end. The detector use a series of photomultiplier tubes (PMT) to generate signals associated with particular events. This research focuses on studying the effects of external magnetic fields on the collection efficiency of the PMT. Upon introducing an external magnetic field near the PMT, the observed single photo-electron (SPE) emission rate decreases. Magnetic fields of equal strength and opposite orientation to the external field are created by applying current to bucking coils (BC) placed around the individual PMT. Data indicates a relationship between SPE emission rates, and collection efficiency distributions. Upon being placed in Hall C, this relationship is used to set the appropriate current for each BC. The correct calibration of the PMT yields a large collection efficiency, thereby allowing particles detected by the WC to be categorized accurately and smooth operation of experiment E05-115.

Maxwell, Victor; Reinhold, Joerg

2009-10-01

344

Effect of cryoprotectants on certain seminal attributes and on the fertility of buck spermatozoa.  

PubMed

Semen samples were obtained from 12 bucks (3 Beetal, 3 Black Bengal and 6 Beetal x Black Bengal) and 10 different extenders were constituted with varying concentrations of glycerol, DMSO, glycerol + DMSO and glycerol + lactose as the sperm cryoprotective agents. After the collection of semen samples, they were assessed for quality, diluted in different extenders after removal of seminal plasma, packaged in ministraws and frozen after equilibration (5'C) for 5 h. The samples were evaluated immediately after equilibration and again 24 h after freezing for progressive motility, percentage of live spermatozoa and acrosome, head and tail abnormalities. Both motility and the percentage of live spermatozoa were most affected by extenders containing only DMSO and these values improved in glycerol + DMSO extenders as the concentration of glycerol was increased while DMSO was decreased. However, these values were significantly higher in extenders containing glycerol + lactose as the cryoprotective agents, and were found to increase with increased concentration of lactose, being highest in TYGL (180). Acrosomal and tail abnormalities tended to increase between post equilibration and post thawing stage, and were higher in extenders containing the higher levels of DMSO. Significantly (P < 0.01) lower percentages of abnormalities were recorded in the glycerol + lactose extenders. The fertility results showed nonsignificant effect of extenders on the conception rate of does. PMID:16727691

Singh, M P; Sinha, A K; Singh, B K

1995-04-15

345

Two new methanol converters  

SciTech Connect

Two novel converter systems were developed for the manufacture of methanol from synthesis gas: the Gas-Solid-Solid Trickle Flow Reactor (GSSTFR) and the Reactor System with Interstage Product Removal (RSIPR). In the GSSTFR version, the product formed at the catalyst surface is directly removed from the reaction zone by means of a solid adsorbent. This adsorbent continuously trickles over the catalyst bed. High reactant conversions up to 100% can be achieved in a single pass so that the usual recycle loop for the unconverted reactants is absent or greatly reduced in size. In the RSIPR version, high conversions per pass are achieved in a series of adiabatic or isothermal fixed bed reactors with selective product removal in absorbers between the reactor stages. The feasibility and economics of the two systems are discussed on the basis of 1,000 tpd methanol plants compared with a low-pressure Lurgi system.

Westerterp, K.R.; Bodewes, T.N.; Vrijiand, M.S.A.; Kuczynski, M. (Twente Univ. of Technology, Enschede (NL))

1988-11-01

346

Converting industrial boilers  

SciTech Connect

Based on the limitations of retrofit applications, a summary is presented of means by which existing oil or gas fired boilers can be converted to coal utilization. Boiler capacity is discussed as well as space limitations, particulate emissions, ash and cinder formation, air pollution, and effectiveness. Specifically, the following modes of firing are discussed: (1) spreader stoker firing; (2) pulverized coal firing; (3) producer gas firing; and (4) fluidized bed coal firing. Outputs in the range of 20,000 to 500,000 pph are considered. Auxillary equipment, particulate emissions, SO/sub 2/ emissions, and nitrogen oxide emissions are discussed briefly. A listing of all design factors to be considered (if coal firing is used) is included. (MJJ)

Dunphy, D.F.; Ramapriya, V.S.

1981-03-01

347

Fluorescent radiation converter  

NASA Technical Reports Server (NTRS)

A fluorescence radiation converter is described which includes a substantially undoped optically transparent substrate and a waveshifter coating deposited on at least one portion of the substrate for absorption of radiation and conversion of fluorescent radiation. The coating is formed to substantially 1000 g/liter of a solvent, 70 to 200 g/liter of an organic polymer, and 0.2 to 25 g/liter of at least one organic fluorescent dye. The incoming incident radiation impinges on the coating. Radiation is absorbed by the fluorescent dye and is re-emitted as a longer wavelength radiation. Radiation is trapped within the substrate and is totally internally reflected by the boundary surface. Emitted radiation leaves the substrate ends to be detected.

Viehmann, W. (inventor)

1981-01-01

348

Electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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.

Bailey, R. L. (inventor)

1973-01-01

349

Unity power factor converter  

NASA Technical Reports Server (NTRS)

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.

Wester, Gene W. (Inventor)

1980-01-01

350

Design of a novel multi-chip power module for a three-phase buck+boost unity power factor utility interface supplying the variable voltage DC link of a square-wave inverter drive  

Microsoft Academic Search

The power semiconductors of one bridge leg of the buck-type input stage of a three phase buck+boost PWM rectifier are integrated into a novel power module. The basic function of the rectifier system is described, and the current stresses on the power semiconductors are calculated analytically. By an experimental analysis of the module, the switching losses of the power transistors

Martina Baumann; Franz Stogerer; Johann W. Kolar; Andreas Lindemann

2001-01-01

351

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

PubMed

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

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

2007-04-01

352

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

USGS Publications Warehouse

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

Sloto, Ronald A.; Grazul, Kevin E.

1995-01-01

353

Thermionic Converter Life and Repeatability Investigation.  

National Technical Information Service (NTIS)

This report covers work on thermionic converters, generators, and thermionic converter additives. Efforts included emitter work function measurements of seven converters which are on life-test and collector work function measurements of these converters. ...

C. Z. Kamien L. van Someren

1966-01-01

354

Photovoltaic energy converters  

NASA Astrophysics Data System (ADS)

The operational principles and numerical models for various significant parameters of solar cell performance are explored. Photovoltaics are semiconductor materials which experience quantum electronic trannsitions when a photon is absorbed. Electron hole pairs produced have a potential that can be converted into electrical energy. The photon energy must exceed the band-band transition energy band gap of the material for the absorption to occur. Each semiconductor material, e.g., Si, GaAs, CdS, etc., used for solar cells features a particular absorption coefficient, and production economies are partially dependent on the development of cells which are thinner and have a broad spectral response, such as found with amorphous Si. The functional characteristics of the junction between layers of a photovoltaic cell are also significant for the cell efficiency, as are the cell temperature and wiring interconnection with other cells. The maximum power delivered is a function of the fill factor, short circuit current, and open circuit voltage. The total efficiency can be augmented through concentrating configurations and by manufacturing tandem cells, which permit efficiencies of 30 percent.

Bloss, W. H.

355

Wind power converter  

SciTech Connect

A high torque windmill is provided for use in converting wind power to usable energy, having a vertical axis about which a plurality of flexible vanes are journaled for rotation and spaced radially therefrom. The vanes are circumferentially spaced and mounted on a rigid circular, multi-sided support member which comprises the rotor journaled for rotation about the vertical mounting axis. Each vane comprises a conical member made of a dacron material and open at opposed ends thereof. A plurality of rods are held in pockets located about the conical surface for maintaining the desired conical configuration. These rods extend beyond each pocket at the smaller end of the cone, for fitting into tubular members fastened to the rotor to hold the vanes in place. Adjacent vanes are offset from the plane of rotation by 15 degrees in opposite directions (That is, up and down) in order to maximize the amount of captured wind power. The foregoing design provides a low speed high torque multi-directional windmill unit.

Tornquist, A.

1982-12-21

356

Pulsed thermionic converter study  

NASA Technical Reports Server (NTRS)

A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

1976-01-01

357

Indian Converts Collection  

NSDL National Science Digital Library

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

358

NOVEL topology of traction converter with single phase Matrix converter  

Microsoft Academic Search

This paper presents research motivated by industrial demand for special traction drive topology devoted to minimization of traction transformer weight of traction vehicles. The main attention has been given to the special traction drive topology for AC power systems: input high voltage trolley converter (single phase) - middle frequency transformer (single phase) - output converter (single phase voltage-source active rectifier

PITTERMANN Martin; DRÁBEK Pavel; CÉDL Marek

2009-01-01

359

Bandwidth considerations for multilevel converters  

Microsoft Academic Search

Multilevel converters can achieve an overall effective switch frequency multiplication and consequent ripple reduction through the cancellation of the lowest order switch frequency terms. This paper investigates the harmonic content and the frequency response of these multimodulator converters. It is shown that the transfer function of uniformly sampled modulators is a bessel function associated with the inherent sampling process. Naturally

Geoff Walker; Gerard Ledwich

1999-01-01

360

PWM Converter Power Density Barriers  

Microsoft Academic Search

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

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

2007-01-01

361

Thyristor converter simulation and analysis  

SciTech Connect

In this paper we present a simulation on thyristor converters. The simulation features nonlinearity, non-uniform firing, and the commutations. Several applications such as a current regulation, a converter frequency characteristics analysis, and a power line disturbance analysis will be presented. 4 refs., 4 figs.

Zhang, S.Y.

1991-01-01

362

Magnetic integration for interleaved converters  

Microsoft Academic Search

In this paper several techniques for integration of magnetic components in interleaved converters are analyzed. Magnetic components define the way the energy is transformed. Several opposite approaches can be considered: from decoupled integrated inductors to tightly coupled inductors. The integration of inductors in the same core for multiphase converters is especially analyzed from the point of view of size, losses

P. Zumel; O. Garcia; J. A. Cobos; J. Uceda

2003-01-01

363

The Angiotensin I Converting Enzyme.  

National Technical Information Service (NTIS)

The angiotensin I converting enzyme (kininase II; peptidyl dipeptidase; EC 3.4. 15.1) has a dual function: it converts angiotensin I to angiotensin II and it inactivates bradykinin. Lung, kidney, guinea pig plasma and testicles are among the richest sourc...

E. G. Erdos

1977-01-01

364

Proposed electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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.

Bailey, R. L.

1973-01-01

365

Resonant AC to AC converter  

Microsoft Academic Search

This paper proposes a novel, power electronics system, a series resonant AC to AC converter, capable of converting a single phase AC supply of frequency fi, into a balanced three-phase supply of frequency foc that may he both higher as well as lower to the input frequency. Use of microcontrollers to control the trigger pulses has made it more versatile.

Vineeta Agarwal; Sachin Nema

2005-01-01

366

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

367

An Induction Motor Drive System Based on the Back-To-Back Connection of Two Five-Level Diode-Clamped PWM Converters  

NASA Astrophysics Data System (ADS)

This paper discusses a 6.6-kV transformerless motor drive system based on the back-to-back connection of two five-level diode-clamped PWM converters. In addition, this paper designs, constructs and experimentally tests a down-scaled model rated at 200V and 5.5kW. This system consist of the two five-level converters, a common dc-link, and voltage-balancing circuits using two bi-directional buck-boost choppers. Experimental results obtained from the down-scaled model verify the validity of the system design, giving promise of the viability of the 6.6-kV transformerless motor drive system.

Kondo, Yosuke; Natchpong, Hatti; Akagi, Hirofumi

368

Distribution of caprine arthritis encephalitis virus provirus, RNA, and antigen in the reproductive tract of one naturally and seven experimentally infected bucks.  

PubMed

Caprine arthritis encephalitis is a worldwide, multisystemic disease caused by a small ruminant lentivirus. Although the main route of transmission is oral, detection of proviral DNA of the caprine arthritis encephalitis virus (CAEV) in caprine semen has been previously described. However, the presence of viral antigens in the male reproductive tract has apparently never been reported. The objective was to study lesions in the buck reproductive system and to detect, in these tissues, the presence of proviral DNA, viral RNA and CAEV antigens. Tissues from eight CAEV-infected bucks (one naturally and seven experimentally infected) were analyzed by histopathology, nested polymerase chain reaction, reverse transcriptase-polymerase chain reaction, and immunohistochemistry. Interstitial pneumonia, synovitis, and lesions in the male reproductive tract were detected in some of the bucks. Proviral DNA was detected in the lungs and joints as well as in the reproductive systems of all animals, whereas viral RNA was detected only in the genital tract of the naturally infected buck. Viral antigens were immunostained in most of the organs of the male reproductive tract. This report was apparently the first to clearly demonstrate CAEV antigen expression in the male reproductive tract, which indicates the possibility of venereal transmission of CAEV. PMID:23973050

Turchetti, Andréia P; Paniago, Juliana J; da Costa, Luciana F; da Cruz, Juliano C M; Braz, Gissandra F; Gouveia, Aurora M G; Paixão, Tatiane A; Santos, Renato L; Heinemann, Marcos B

2013-11-01

369

Effect of different levels of bee pollen on performance and blood profile of New Zealand White bucks and growth performance of their offspring during summer and winter months.  

PubMed

The effect of bee pollen on productive and reproductive performances of adult buck rabbits and their offspring was studied during winter and summer seasons. Forty New Zealand White bucks were equally divided among four groups feeding the same commercial diet and receiving a water solution containing, respectively, 0 (control), 100, 200 and 300 mg bee pollen/kg body weight, twice per week along two experimental periods. The experimental periods were listed for ten weeks both during winter (30-40 weeks of age) and summer seasons (56-66 weeks of age). During the trials body weight, body weight gain, total feed intake, semen quality, fertility and blood constituents were determined. Fertility was determined after natural mating with no treated females. For each season, 80 weaned rabbits obtained from the bucks of the control group were equally divided (20 per group) among 4 levels (0, 100, 200 and 300 mg/kg BW) of bee pollen, given as a water solution twice per week. The offspring sired by bucks given 100, 200 and 300 mg (20 for each group and season) were not administrated bee pollen. The effect of bee pollen on growth performance of rabbits was studied from 4 to 12 weeks of age. Bee pollen at 200 mg/kg BW significantly (p< 0.01) improved semen quality, increased fertility percentage, improved biochemical profiles of blood and helps outstanding of bucks during both seasons. The same concentration of bee pollen increased body weight gain and survival rate and reduced feed intake and feed conversion ratio of offspring up to 12 weeks of age. PMID:20455966

Attia, Y A; Al-Hanoun, A; Bovera, F

2011-02-01

370

High-temperature solar converter  

NASA Technical Reports Server (NTRS)

Converter has parabolic concentrator that directs sunlight on three-dimensional absorber assembly within an evacuated glass cylinder. No tracking mechanism is required. Concentrator aperture is adjustable to modify concentration in direct or diffuse sunlight. Range of adjustment is small.

Ascher, G.

1978-01-01

371

Wind/water energy converter  

NASA Technical Reports Server (NTRS)

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.

Paulkovich, J.

1979-01-01

372

Method for Converting Chrysotile Asbestos.  

National Technical Information Service (NTIS)

The patent application discloses a method for converting chrysotile asbestos to a magnesium hydroxide rich composition by subjecting the asbestos to repeated cycles of treatment with a 20 to 60 percent solution of potassium hydroxide heated to a temperatu...

Y. Harada

1973-01-01

373

Radiation tolerant power converter controls  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

374

HIGH EFFICIENCY AUXILIARY POWER CONVERTERS  

Microsoft Academic Search

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

Geoff Walker

375

Multilevel converters for power system applications.  

National Technical Information Service (NTIS)

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 m...

J. S. Lai J. P. Stovall F. Z. Peng

1995-01-01

376

Public health assessment for Revere Chemical Company, Nockamixon, Bucks County, Pennsylvania, Region 3. Cerclis No. PAD051395499. Final report  

SciTech Connect

The Revere Chemical National Priorities List (NPL) site is located on the southeast side of Pennsylvania State Route 611, approximately three quarters of a mile south of the town of Revere in Nockamixon Township, Bucks County, Pennsylvania. Operations at the Revere Chemical site were initiated in 1963 and reportedly involved the recycling of spent chromic acid solutions, the recovery of copper from electric plating solution, and the reclamation of metals from printed circuit boards. The process area soils are contaminated with volatile organic compounds and metals. Soil contamination decreases markedly with distance from the process area. Trichloroethene (TCE) and 1,2,4-trichlorobenzene (TCB) were detected in on-site monitoring well MW-4 at concentrations of 110 micrograms per liter and 41 micrograms/liter, respectively. The Revere Chemical site currently represents an indeterminate public health hazard since groundwater flow direction has not been fully characterized and not all residential wells near the site have been sampled.

Not Available

1994-01-06

377

PWM Converter Power Density Barriers  

NASA Astrophysics Data System (ADS)

Power density of power electronic converters has roughly doubled every 10 years since 1970. Behind this trajectory is the continuous advancement of power semiconductor devices, which has increased the converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts and passive components are major barriers for a continuation of this trend. To identify such technological barriers, this paper investigates the volume of the cooling system and passive components as a function of the switching frequency for power electronic converters and determines the switching frequency that minimizes the total volume. A power density limit of 28kW/dm3 at 300kHz is calculated for an isolated DC-DC converter, 44kW/dm3 at 820kHz for a three-phase unity power factor PWM rectifier, and 26kW/dm3 at 21kHz for a sparse matrix converter. For single-phase AC-DC conversion a general limit of 35kW/dm3 results from the DC link capacitor. These power density limits highlight the need to broaden the scope of power electronics research to include cooling systems, high frequency electromagnetics, interconnection and packaging technology, and multi-domain modelling and simulation to ensure further advancement along the power density trajectory.

Kolar, Johann W.; Drofenik, Uwe; Biela, Juergen; Heldwein, Marcelo; Ertl, Hans; Friedli, Thomas; Round, Simon

378

Fish Assemblages and Benthic Habitats of Buck Island Reef National Monument (St. Croix, U.S. Virgin Islands) and the Surrounding Seascape: A Characterization of Spatial and Temporal Patterns.  

National Technical Information Service (NTIS)

The report provides a spatial and temporal characterization of the fish and benthic communities of Buck Island Reef National Monument and the surrounding seascapes of northeastern St. Croix, United States Virgin Islands. The project is a component of NOAA...

C. Caldow C. Jeffrey M. E. Monaco M. S. Kendall S. D. Hile S. J. Pittman

2008-01-01

379

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

USGS Publications Warehouse

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.

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

2012-01-01

380

Angiotensin converting enzyme inhibitor therapy.  

PubMed

Angiotensin converting enzyme inhibitor therapy decreases the production of the vasoconstrictive angiotensin II and reduces the degradation of certain kinines of vasodilatator action. Of captopril, enalapril, and lysinopril marketed abroad, only captopril of shorter action is available in Hungary. Angiotensin converting enzyme inhibitors are new means for the therapy of hypertension and congestive heart failure. Captopril seems to be effective at an early stage of heart failure. It slows down or even inhibits the progression of heart failure. New aspects of therapy have been revealed. It may be successfully used in angina pectoris, for the prevention of reperfusion arrhythmias accompanying myocardial infarction, for the treatment of renoparenchimal renal diseases, diabetic nephropathy. The side-effects, interactions, and dosage of angiotensin converting enzyme inhibitors have also been discussed. PMID:1948779

Róna, G

1991-01-01

381

Topological constraints on basic PWM converters  

NASA Astrophysics Data System (ADS)

A modeling and synthesis technique is introduced for single-ended ladder-structured dc-dc converter topologies. Topological constraints are derived that enhance the understanding of structural properties of converter circuits and clarify the roles of inductors and capacitors in various converters using magnetic or capacitive energy storage/transfer mechanisms. The exact duality relationships among the basic converter topologies are established.

Liu, Kwang-Hwa; Lee, Fred C.

382

Converting Work into College Credits  

ERIC Educational Resources Information Center

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.…

Hoffman, Joseph A.

1976-01-01

383

Charge-pump voltage converter  

DOEpatents

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.

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

2009-11-03

384

Converting accounts receivable into cash.  

PubMed

In recent years, increasing numbers of healthcare providers have converted their accounts receivable into cash through a process called securitization. This practice has gained popularity because it provides a means to raise capital necessary to healthcare organizations. Although securitization transactions can be complex, they may provide increased financial flexibility to providers as they prepare for continuing change in the healthcare industry. PMID:10145096

Folk, M D; Roest, P R

1995-09-01

385

Hoffman HSPP-1 Solar Converter.  

National Technical Information Service (NTIS)

This report describes an application of the Hoffman HSPP-1 Solar Converter as a potential power source for minor aids to navigation. This project and report's purpose is to study solar cells as a potential source for minor lights, and to define conditions...

R. W. Witter

1968-01-01

386

Switched-capacitorized DC\\/DC converters  

Microsoft Academic Search

Switched converter (SC) DC\\/DC converters are new prototype of DC\\/DC Conversion technology. Since switched capacitor can be integrated into a power IC chip, consequently, these converters have small size and high power density. Switched capacitor can be used in voltage-lift technique to construct DC\\/DC converters. The clue is that for the converters operating in input current discontinuous mode (ICDM) the

Fang Lin Luo

2009-01-01

387

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

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.

Clune, John W.; Denver, Judith M.

2012-01-01

388

Operation and control of a high performance inverter consisting of a buck-boost and a zero switching losses H-bridge for photovoltaic systems  

Microsoft Academic Search

This paper analyses the control of a especial inverter topology consisting of a buck-boost and a H-bridge in which the first one generates a rectified output voltage and the second one inverts one of each two half cycles. As a consequence, the H-bridge commutates at twice the line frequency and, what is more important, at zero voltage. Switching losses are

P. Sanchis; A. Ursua; E. Gubia; L. Marroyo

2004-01-01

389

Portable convertible blast effects shield  

DOEpatents

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.

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

390

Portable convertible blast effects shield  

DOEpatents

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.

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

391

Portable convertible blast effects shield  

DOEpatents

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.

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

392

An improved interleaved forward converter  

Microsoft Academic Search

Operations and steady-state analysis for an improved interleaved forward converter topology are presented in this paper. Not only zero-voltage-switching (ZVS) can be achieved through the resonance that exists between the transformers magnetizing inductances and the parasitic capacitance of switches, but also proper transformer reset and lower output voltage can be achieved by adding two clamp capacitors, such as topology of

Jinbin Zhao; Masaoki Sekine; Shuuichi Ushiki; T. Sato; T. Nabeshima; T. Nakano

2006-01-01

393

Resonant converter power line conditioner  

Microsoft Academic Search

A power description is given of the operation and design of a power-line conditioner (PLC) utilizing the principles of a resonant converter. The PLC uses an L-C circuit which resonates at a high frequency. The PLC is connected in parallel with a load, and it injects high-frequency resonant current pulses into the supply lines at regular sampling intervals so that

S. Deb; R. G. Hoft

1988-01-01

394

High efficiency thermionic converter studies  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

395

Active induction balance method for metal detector sensing head utilizing transmitter-bucking and dual current source  

NASA Astrophysics Data System (ADS)

A central problem in a design of frequency domain electromagnetic induction sensors used in landmine detection is an effective suppression of a direct inductive coupling between the transmitter and the receiver coil (induction balance, IB). In sensing heads based on the transmitter-bucking configuration, IB is achieved by using two concentric transmitter coils with opposing exciter fields in order to create a central magnetic cavity for the receiver coil. This design has numerous advantages over other IB methods in terms of detection sensitivity, spatial resolution, sensor dimensions and suitability for model-based measurements. However, very careful design and precise sensing head geometry are required if a single excitation source is used for driving both transmitter coils. In this paper we analyze the IB sensitivity to small perturbations of geometrical properties of coils. We propose a sensor design with dual current source and active induction balance scheme which overcomes the limitations of geometry-based balancing and potentially provides more efficient compensation of soil effects.

Ambruš, D.; Vasi?, D.; Bilas, V.

2013-06-01

396

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

USGS Publications Warehouse

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.

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

2006-01-01

397

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

USGS Publications Warehouse

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

Sloto, Ronald A.

2008-01-01

398

Experimental Study on Alkali Metal Thermoelectric Converter.  

National Technical Information Service (NTIS)

The alkali metal thermoelectric converter (AMTEC) utilizing the sodium ion conducting beta-alumina is a device to convert heat energy to electric energy directly. It is characterized by high conversion efficiencies, high power densities, no moving parts a...

T. Masuda K. Tanaka T. Honda A. Negishi

1989-01-01

399

Large wind energy converter: Growian 3 MW  

NASA Technical Reports Server (NTRS)

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.

Koerber, F.; Thiele, H. A.

1979-01-01

400

The age of multilevel converters arrives  

Microsoft Academic Search

This work is devoted to review and analyze the most relevant characteristics of multilevel converters, to motivate possible solutions, and to show that we are in a decisive instant in which energy companies have to bet on these converters as a good solution compared with classic two-level converters. This article presents a brief overview of the actual applications of multilevel

Leopoldo Franquelo; Jose Rodriguez; Jose Leon; Samir Kouro; Ramon Portillo; Maria Prats

2008-01-01

401

Heat flow in a pyroelectric converter  

Microsoft Academic Search

A simulated pyroelectric converter has been constructed. The heat flow and temperature profiles within the converter have been measured. Computer simulations of the heat flow compare well with the measurements and predict an efficiency of 12 percent of the Carnot limit for a real pyroelectric converter with the operating configuration of the simulation. These heat flow results are useful in

R. B. Olsen; W. F. Butler; J. E. Drummond; D. A. Bruno; J. M. Briscoe

1985-01-01

402

Electromagnetic Compatibility of Matrix Converter System  

Microsoft Academic Search

Abstract. The presented paper ,deals with matrix converters pulse width modulation strategies design with emphasis on the ,electromagnetic compatibility. Matrix converters provide an all-silicon solution to the problem of converting AC power from one frequency to another, offering almost all the features required of an ideal static frequency changer. They possess many ,advantages compared to the conventional voltage or current

Ji?í Lettl; Stanislav Flígl

403

Analytic Signal Converter for Nondestructive Testing.  

National Technical Information Service (NTIS)

An analytic signal converter was developed to improve flaw detection in parts. The converter can resolve echoes 700 ns apart. The converter oprerates in real-time by using a single-sideband conversion technique, Weaver's Method. The transducer range is 1 ...

M. G. Duncan

1986-01-01

404

Mode size converter for a planar waveguide  

US Patent & Trademark Office Database

A process for forming a mode size converter with an out-of-plane taper formed during deposition with a shadow mask is disclosed. Mode-size converters according to the present invention can have any number of configurations. Measured coupling efficiencies for waveguides with mode size converters according to the present invention show marked improvement.

2011-10-25

405

Thermoelectric converters for alternating current standards  

NASA Astrophysics Data System (ADS)

Thermoelectric converters of alternating current remain priority instruments when creating standard equipment. This work presents the results of design and manufacture of alternating current converter for a military standard of alternating current in Ukraine. Results of simulation of temperature distribution in converter elements, ways of optimization to improve the accuracy of alternating current signal reproduction are presented. Results of metrological trials are given. The quality of thermoelectric material specially created for alternating current metrology is verified. The converter was used in alternating current standard for the frequency range from 10 Hz to 30 MHz. The efficiency of using thermoelectric signal converters in measuring instruments is confirmed.

Anatychuk, L. I.; Taschuk, D. D.

2012-06-01

406

Transient voltage blocking for power converter  

US Patent & Trademark Office Database

A power converter includes a transient voltage protection circuit connected between an input of the power converter and a power stage of the power converter. The transient voltage protection circuit provides a low resistance connection from the input of the power converter to the power stage of the power converter when the input voltage is less than a predetermined threshold, but blocks the input voltage from the power stage when the input voltage is equal to or greater than the predetermined threshold voltage. The power converter may be a boost power converter used in a vehicle to provide power from a main power bus of the vehicle to a subsystem of the vehicle such as an anti-lock brake system.

2014-02-25

407

A high-efficiency linear RF power amplifier with a power-tracking dynamically adaptive buck-boost supply  

Microsoft Academic Search

Energy efficiency of RF transceivers is critical and paramount for longer battery life in portable devices, which is improved by operating the power amplifiers (PAs) with higher efficiency. In this paper, the applicability of dynamic-converter-supplied RF PAs' efficiency-enhancement schemes is compared and evaluated for code-division multiple-access (CDMA) applications. The tradeoffs involved in designing switching converters with wide bandwidth (BW) and

Biranchinath Sahu; Gabriel A. Rincón-Mora

2004-01-01

408

Research of an interleaved boost converter with four interleaved boost convert cells  

Microsoft Academic Search

Boost converters are widely used in the low-to-high DC\\/DC application and power-factor-corrected circuits. Based on the interleaved boost converter with coupled inductors, a converter consisting of four interleaved boost converter cells is proposed in this paper. The boost converter cells can share the input current, so this prototype circuit can be designed to have small input current ripple. And when

Chen Chunliu; Wang Chenghua; Hong Feng

2009-01-01

409

Thermionic converter emitter support arrangement  

DOEpatents

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

Allen, Daniel T. (La Jolla, CA) [La Jolla, CA

1990-01-01

410

Thermionic converter emitter support arrangement  

DOEpatents

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

Allen, Daniel T. (La Jolla, CA) [La Jolla, CA

1990-01-01

411

Infrared-to-visible converter  

NASA Astrophysics Data System (ADS)

A quantum well infrared photodetector comprises multiple quantum well detectors formed within a single P-N structure forward-biased by an external voltage source, for directly converting infrared radiation having a wavelength in the range of approximately 4-15 micrometers into visible radiation or near infrared radiation. Multiple quantum well detectors disposed between the P-N contact layers are comprised of alternating gallium arsenide (GaAs) quantum well layers, aluminum gallium arsenide (AlGaAs) barrier layers and alternatively, a blocking layer of aluminum arsenide (AlAs) positioned between a last aluminum gallium arsenide (AlGaAs) barrier layer and the N contact layer; and are forward-biased by the external voltage source in order to produce band-gap luminescence by radiative recombination of excess carriers representative of electrons and holes in the N contact layer when the P contact layer is illuminated with optical energy of incident infrared radiation.

Snow, Eric S.

1994-06-01

412

Air pollution control electrocatalytic converter  

SciTech Connect

This patent describes an electrocatalytic converter. It comprises a base portion having a fixing portion formed on an outer wall thereof and a terminal insulatedly provided therein and connected to an electrical source; a heater means integrally connected to the base portion, having heating surface and heating fins formed on a wall surface thereof and composed of a catalyst a transition metal; a heating means comprising a resistive exothermic element connected to the terminal of the base portion. The resistive exothermic element being provided adjacent to the heating surface within the heating means; a plurality of heating means fins outwardly extending projections radially mounted on the outer wall of the base portion and the base portion and heating fins are covered with a thin coating of platinum, palladium and rhodium.

John, M.

1989-08-01

413

Thermionic converter studies at Thermo Electron  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

414

Performance of Power Converters at Cryogenic Temperatures  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

415

Development of a Modular Power Converter  

NASA Astrophysics Data System (ADS)

This report describes the most important details of elaboration of a versatile power module that can be utilized as a part of various converters. Two or more modules connected together can form a frequency converter or multilevel converter or 3-phase inverter/rectifier etc. Initially the module was developed for fast prototyping of uninterruptible power supplies and energy systems with alternative energy sources. The module can be used also as a basis for laboratory equipment of the power electronics course.

Stepanov, A.; Biesenieks, L.; Sokolovs, A.; Galkin, I.

2009-01-01

416

Converters of the levels of logical elements  

NASA Astrophysics Data System (ADS)

Attention is given to the basic characteristics and circuit diagrams of converters (matchers) of the levels of various types of integrated logical elements. Reversible level converters of the following types are examined: TTL-ECL, TTL-I2L, TTL-MOS, ECL-I2L, ECL-MOS, and I2L-MOS. The advantages and drawbacks of these converters are noted.

Mkrtchian, S. O.

1982-10-01

417

Heat flow in a pyroelectric converter  

NASA Astrophysics Data System (ADS)

A simulated pyroelectric converter has been constructed. The heat flow and temperature profiles within the converter have been measured. Computer simulations of the heat flow compare well with the measurements and predict an efficiency of 12 percent of the Carnot limit for a real pyroelectric converter with the operating configuration of the simulation. These heat flow results are useful in considerations of heat engines using active materials other than pyroelectrics, such as Nitinol, when these engines utilize similar heat flow management.

Olsen, R. B.; Butler, W. F.; Drummond, J. E.; Bruno, D. A.; Briscoe, J. M.

1985-12-01

418

Inverting ZCS Switched-Capacitor Bidirectional Converter  

Microsoft Academic Search

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

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

2006-01-01

419

Low Frequency Characterization of PWM Converters  

Microsoft Academic Search

Low frequency components of states or outputs in pulse-width modulation (PWM) dc and ac converters can be characterized by differential equations called describing state-space equations. These equations are derived by inspection of converter topology and use of switching functions and duty ratios. Their steady-state and small-signal dynamic solutions show how energy-storage elements in a converter\\/load system shape the frequency response

Khai D. T. Ngo

1986-01-01

420

A Novel Lossless Snubber for Boost Converters  

Microsoft Academic Search

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

J. Marshall; M. Kazerani

2006-01-01

421

Interleaved converters operation based on CMC  

Microsoft Academic Search

A new family of low-ripple DC-to-DC switching converters based on a parallel connection of N-identical boost converters with current-mode control (CMC) is presented. The CMC strategy ensures that all the converters operate at the same duty cycle, sharing an equal amount of input current and forcing the output voltage to be an integer multiple (N) of the input voltage. As

Roberto Giral; L. Martinez-Salamero; S. Singer

1999-01-01

422

One-cycle control of switching converters  

Microsoft Academic Search

A pulsed nonlinear control technique, one-cycle control, is introduced. This technique takes advantage of the pulsed and nonlinear nature of switching converters and achieves instantaneous control of the average value of the chopped voltage or current. This technique provides fast dynamic response and good input-perturbation rejection. It is suitable for the control of pulsewidth-modulated (PWM) converters and quasi-resonant converters. The

Keyue M. Smedley; Slobodan Cuk

1991-01-01

423

Simplified Heat-Source/Thermionic Converter  

NASA Technical Reports Server (NTRS)

Radiation coupling of heat from heat-source cylinder to converter cylinder through vacuum gap eliminates need for high-temperature electrical insulators between reactor heat pipes and thermionic converters. In addition no radiatior heat pipe is necessary because collectors of thermionic converters from which excess heat must be removed radiate directly to space. New design concept is also applicable to terrestrial and non-nuclear thermionic power supplies.

Shimada, K.

1983-01-01

424

A closely regulated TWT converter.  

NASA Technical Reports Server (NTRS)

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.

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

1971-01-01

425

Vacuum-insulated catalytic converter  

DOEpatents

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.

Benson, David K. (Golden, CO)

2001-01-01

426

Converter concepts to increase the integration level  

Microsoft Academic Search

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

Jelena Popovic; J. A. Ferreira

2005-01-01

427

High voltage multilevel converter with regeneration capability  

Microsoft Academic Search

This paper presents a multilevel converter with regeneration capability. The converter is based on the series connection of several power cells, each working with reduced voltage and with an active front end at the line side. This paper presents the control method of each cell, the use of phase-shifting techniques to reduce the current distortion and criteria to select the

Jose Rodriguez; L. Moran; A. Gonzalez; C. Silva

1999-01-01

428

Multilevel converters for 10 MW Wind Turbines  

Microsoft Academic Search

Several promising multi-level converter configurations for 10 MW Wind Turbines both with direct drive and one-stage gear box drive using Permanent Magnet Synchronous Generator (PMSG) are proposed, designed and compared. Reliability is a crucial indicator for large scale wind power converters, therefore the evaluations are mainly focused on the power device thermal performances, which are closely related to the life

Ke Ma; Frede Blaabjerg

2011-01-01

429

Predictive controller for interleaved boost converter  

Microsoft Academic Search

In this paper, a predictive current control technique is proposed for interleaved boost converter operating in continuous current mode. State-space averaging technique is used to model the interleaved boost converter system. Predictive valley current control law with trailing edge modulation is derived so as to track the source current to the predefined reference value. The control loop is designed to

C. Sudhakar Babu; M. Veerachary

2005-01-01

430

EMI reduction by interleaving of power converters  

Microsoft Academic Search

Switched converters are a source of EMI due to the hard switching and abrupt edges in the current and voltage waveforms. Interleaved converters can reduce the EMI at the source, minimizing the generation of conducted EMI, without changing the normal operation of the circuit. Input filter can be reduced, radiated EMI is lower and internal EMI problems are minimized. This

P. Zumel; O. Garcia; J. A. Cobos; J. Uceda

2004-01-01

431

Efficient Implementation of Sample Rate Converter  

Microsoft Academic Search

Within wireless base station system design, manufacturers continue to seek ways to add value and performance while increasing differentiation. Transmit\\/receive functionality has become an area of focus as designers attempt to address the need to move data from very high frequency sample rates to chip processing rates. Digital Up Converter (DUC) and Digital Down Converter (DDC) are used as sample

2010-01-01

432

Power Converters Secure Electronics in Harsh Environments  

NASA Technical Reports Server (NTRS)

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.

2013-01-01

433

Zero voltage switching approach for flyback converter  

Microsoft Academic Search

A zero voltage switched flyback power converter which realizes soft switching for every semiconductor is proposed. The sinusoidal resonant current flows through the secondary side rectifier diode and zero current switching of the diode is realized. Diode recovery is not generated. The proposed converter can operate with constant frequency pulse width modulation. High frequency switching and low noise are achieved

K. Yoshida; T. Ishii; N. Nagagata

1992-01-01

434

Converter Design for a Model Solar Car  

Microsoft Academic Search

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

Richard Duke; Simon Round

435

FPAA Prototyping of ?? Analog Digital Converters  

Microsoft Academic Search

A prototyping method for designing mixed signal systems has been presented in the paper. The method is based on implementation of field programmable analog arrays (FPAA) to configure and reconfigure mixed signal systems. A ?? analog digital converter (ADC) structure has been used as an example. The circuit characteristics have been measured and then the structure of the converter has

R. Suszynski; K. Wawryn

2006-01-01

436

Flexible multilevel boost DC-AC converter  

Microsoft Academic Search

In this paper, incorporation of multi-output boost (MOB) converter by multilevel inverter is proposed. Renewable energy sources such as fuel cell and photovoltaic produce low level of voltage. So to increase the magnitude of the voltage, dc-dc boost converter is used. Simple control and flexible operation for generating different number of output with desired voltage level is the main reason

Ebrahim Babaei; Ali Nahavandi

2012-01-01

437

An Examination of Mandatorily Convertible Preferred Stock  

Microsoft Academic Search

I investigate the determinants of the use of mandatorily convertible preferred stock and assess market reaction to its issue. The security is dividend enhanced and converted into common stock within four years. Issuers have high debt ratios, low interest coverage, and bankruptcy risk. Market response to the issue was neutral suggesting the preferred issue resolved the lemon problem associated with

Nancy White Huckins

1999-01-01

438

Laser energy converted into electric power  

NASA Technical Reports Server (NTRS)

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.

Shimada, K.

1973-01-01

439

A novel power converter for photovoltaic applications  

NASA Astrophysics Data System (ADS)

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

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

440

Characteristics of firms that issue convertible debt versus convertible preferred stock  

Microsoft Academic Search

This study examines the characteristics of firms that issue convertible debt versus firms that issue convertible preferred stock. The findings are consistent with the agency, information asymmetry, optimal capital structure, financial distress, and tax benefits hypotheses. The findings also indicate that these two types of convertible securities are used to raise external capital by distinctively different groups of firms. First,

Hei Wai Lee; Raymond E. Figlewicz

1999-01-01

441

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

USGS Publications Warehouse

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.

Risser, Dennis W.; Bird, Philip H.

2003-01-01

442

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

NASA Astrophysics Data System (ADS)

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.

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

2006-05-01

443

'The buck stops here': accepting responsibility for learning and actions after graduation from a problem-based learning nursing education curriculum.  

PubMed

Despite the increased attention that problem-based learning has received as an appropriate pedagogical technique for educating adults for professional practice, reports that evaluate the process are rare and usually relate to professions other than nursing. A study was undertaken in order to discover the graduates' own perceptions of a problem-based learning programme and its effectiveness in preparing them for the reality of their chosen profession. Twelve practising graduate nurses who had completed the programme were interviewed according to the ethnographic method. Three categories were identified from the data: 'and all of a sudden...', which describes the transition from PBL student to staff nurse; 'not an unthinking assistant', where the characteristics that the PBL graduates believe make them different from traditionally trained nurses are described; and 'the buck stops here', which describes the sense of personal responsibility that the graduates experience in terms of their learning and actions. PMID:9637330

Biley, F C; Smith, K L

1998-05-01

444

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

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.

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

2006-01-01

445

Design Methodology for Switched-Capacitor DC-DC Converters.  

National Technical Information Service (NTIS)

Switched-capacitor (SC) DC-DC power converters are a subset of DC-DC power converters that use a network of switches and capacitors to efficiently convert one voltage to another. Unlike traditional inductor-based DC-DC converters, SC converters do not rel...

M. D. Seeman

2009-01-01

446

A new method to regulate resonant converters  

NASA Astrophysics Data System (ADS)

A resonant frequency-modulation method is presented as an alternative to the switching frequency-modulation method to regulate resonant converters. A switch-controlled inductor and switch-controlled capacitor, in which switching losses are found to be very low due to zero-current or zero-voltage switching, are developed to do so. A new family of resonant converters that are regulated at a fixed switching frequency is proposed. A steady-state analysis of the Class E resonant converter regulated by a switch-controlled capacitor is presented. Theoretical and experimental results verify the validity of the proposed method. The efficiency measured from a breadboard of a 1-MHz, 5-V, 25-W Class E regulated resonant dc-dc converter is up to 83 percent.

Gu, Wen-Jian; Harada, Koosuke

1988-10-01

447

Departure from Lte in the Thermionic Converter.  

National Technical Information Service (NTIS)

Reported electron temperature and density profiles across the interelectrode space of a thermionic converter were analyzed. For each set of Te and Ne points, effective coefficients for ionization and for radiative energy loss are computed. These coefficie...

D. W. Norcross

1967-01-01

448

Converting Garbage to Gold: Recycling Our Materials.  

ERIC Educational Resources Information Center

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)

Chandler, William U.

1984-01-01

449

Bacterial Rhodopsin as a Light Energy Converter.  

National Technical Information Service (NTIS)

The structure, function, and energy converting properties of bacteriorhodopsin are analyzed. Bacteriorhodopsin is a complex of retinal and protein which makes up the purple membrane in halophilic bacteria. The membrane serves as a light energy source for ...

D. Oesterhelt

1975-01-01

450

Transient Waveform Analysis of Switching Converter.  

National Technical Information Service (NTIS)

The DC to DC series resonance converter circuit using antiparallel diodes to introduce two additional controlled time intervals for diode conduction has been modeled as an idealized series capacitor resonance circuit with four cyclic switching states. For...

E. Kittl

1977-01-01

451

Converted neural cells: induced to a cure?  

PubMed Central

Many neurodegenerative disorders such as Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and others often occur as a result of progressive loss of structure or function of neurons. Recently, many groups were able to generate neural cells, either differentiated from induced pluripotent stem cells (iPSCs) or converted from somatic cells. Advances in converted neural cells have opened a new era to ease applications for modeling diseases and screening drugs. In addition, the converted neural cells also hold the promise for cell replacement therapy (Kikuchi et al., 2011; Krencik et al., 2011; Kriks et al., 2011; Nori et al., 2011; Rhee et al., 2011; Schwartz et al., 2012). Here we will mainly discuss most recent progress on using converted functional neural cells to treat neurological diseases and highlight potential clinical challenges and future perspectives.

Zhang, Weiqi; Duan, Shunlei; Li, Ying; Xu, Xiuling; Qu, Jing; Zhang, Weizhou; Liu, Guang-Hui

2014-01-01

452

Large-Scale Digitizer System, Analog Converters.  

National Technical Information Service (NTIS)

Analog to digital converter circuits that are based on the sharing of common resources, including those which are critical to the linearity and stability of the individual channels, are described. Simplicity of circuit composition is valued over other mor...

R. F. Althaus K. L. Lee F. A. Kirsten L. J. Wagner

1976-01-01

453

NUCLEAR-OPTICAL CONVERTERS FOR NEUTRON DETECTION  

Microsoft Academic Search

Nuclear-optical converters (NOC) are fission chambers based upon fission fragment energy conversion to optical radiation in gas luminescent media. The All-Russia Scientific Research Institute of Experimental Physics (VNIIEF) has demonstrated that it is possible to construct nuclear-optical converters with characteristics appropriate for a wide-range of measuring applications including neutron detection in nuclear power plants. These detectors may be used a

A A Sinyanskii; S P Melnikov; L E Dovbysh; G L Johnson

2004-01-01

454

Zero-current transition interleaved boost converter  

Microsoft Academic Search

In this paper, a new ZCS PWM auxiliary circuit for the interleaved boost converter is introduced which uses only one auxiliary switch to provide soft-switching condition. In the proposed interleaved converter, soft switching is obtained for all semiconductor devices. The main and auxiliary switches turn on and off under zero-current condition. Thus, the reverse-recovery losses of boost diodes are reduced

Mahdi Rezvanyvardom; Ehsan Adib; Hosein Farzanehfard

2011-01-01

455

Multilevel converters for large electric drives  

Microsoft Academic Search

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

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

1999-01-01

456

On lossless switched-capacitor power converters  

SciTech Connect

This paper addresses the design of efficient switched-capacitor power converters. The discussion starts with a review of the fundamental limitation of switched-capacitor circuits which shows that the topology of such circuits and the ``forced`` step changes of capacitor voltages are the inherent attributes of power loss. Although the argument follows from a rather trivial result from basic circuit theory, it addresses an important issue on the maximum efficiency achievable in a switched-capacitor converter circuit. Based on the observed topological constraint of switched-capacitor converter circuits, the simplest lossless topology for AC/DC conversion is deduced. Also discussed is a simple version of lossless topology that achieves isolation between the source and the load. Finally, an experimental AC/DC switched-capacitor converter, based on the proposed idea, is presented which demonstrates an improved efficiency over other existing switched-capacitor converters. The proposed AC/DC converter contains no inductors and thus is suitable for custom IC implementation for very low power applications.

Tse, C.K.; Wong, S.C.; Chow, M.H.L. [Hong Kong Polytechnic Univ. (Hong Kong). Dept. of Electronic Engineering] [Hong Kong Polytechnic Univ. (Hong Kong). Dept. of Electronic Engineering

1995-05-01

457

Angiotensin I-Converting Enzyme in the Nephron.  

National Technical Information Service (NTIS)

Goat antibody to swine kidney angiotensin I-converting enzyme was coupled to fluorescein isothiocyanate and was used to react with the converting enzyme in slices of swine kidney. Converting enzyme was present throughout the nephron and was concentrated i...

E. R. Hall J. Kato E. G. Erdos C. J. G. Robinson G. Oshima

1976-01-01

458

Research on Thermionic Converters Using Barium and Cesium Vapor.  

National Technical Information Service (NTIS)

Investigations of thermionic converter operations were conducted utilizing a dual vapor system of barium and cesium. Barium and cesium vapors were introduced into two differently designed converters. The first converter developed an internal short circuit...

J. D. Long

1967-01-01

459

26 CFR 1.305-6 - Distributions of convertible preferred.  

Code of Federal Regulations, 2013 CFR

...corporation of its convertible preferred stock or rights to acquire such stock...The distribution of convertible preferred stock is likely to result in a disproportionate...payable in newly authorized class B preferred stock which is convertible into...

2013-04-01

460

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

Microsoft Academic Search

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

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

2011-01-01

461

An Investigation of Capacitors for Flying Capacitor Converters  

NASA Astrophysics Data System (ADS)

Multi-level converters can essentially reduce harmonics even when their switching frequency is low. Among the various topologies of the multi-level converters, flying capacitor converters are considered to be promising converters for realizing high power density. However, the main circuit of the flying capacitor converters has many capacitors. Therefore, in this study, the volume of the capacitors in the flying capacitor converters is determined by taking into consideration the allowable ripple voltage and temperature rise in the capacitor.

Obara, Hidemine; Kamaga, Masamu; Ito, Takumi; Sato, Yukihiko

462

Bidirectional converter interface for a battery energy storage test bench  

Microsoft Academic Search

This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dc converter with high transformation ratio. The dc-dc converter controls the battery charge\\/discharge current while the grid converter controls the

Ionut Trintis; Stephan Thomas; Tobias Blank; Christoph Roggendorf; Stig Munk-Nielsen; Remus Teodorescu

2011-01-01

463

Materials technology for Stirling space power converters  

NASA Technical Reports Server (NTRS)

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.

Baggenstoss, William; Mittendorf, Donald

1992-01-01

464

Isolated and soft-switched power converter  

DOEpatents

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.

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

2002-01-01

465

Fabrication and life testing of thermionic converters  

NASA Technical Reports Server (NTRS)

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

Yang, L.; Bruce, R.

1973-01-01

466

Materials technology for Stirling space power converters  

NASA Astrophysics Data System (ADS)

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.

Baggenstoss, William; Mittendorf, Donald

1992-07-01

467

Metamaterial polarization converter analysis: limits of performance  

NASA Astrophysics Data System (ADS)

In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.

Markovich, Dmitry L.; Andryieuski, Andrei; Zalkovskij, Maksim; Malureanu, Radu; Lavrinenko, Andrei V.

2013-08-01

468

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?

469

Infrared up-converting phosphors for bioassays.  

PubMed

The development of up-converting phosphor reporter particles has added a powerful tool to modern detection technologies. Carefully constructed phosphor reporters have core-shell structures with surface functional groups suitable for standard bio-conjugations. These reporters are chemically stable, possess the unique property of infrared up-conversion, and are readily detected. In contrast to conventional fluorescent reporters, up-converting phosphor particles do not bleach and allow permanent excitation with simultaneous signal integration. A large anti-Stokes shift (up to 500 nm) separates discrete emission peaks from the infrared excitation source. Along with the unmatched contrast in biological specimens due to the absence of autofluorescence upon infrared excitation, up-converting phosphor technology (UPT) has unique properties for highly-sensitive particle-based assays. The production and characteristics of UPT reporter particles as well as their application in various bioassays is reviewed. PMID:16441160

Corstjens, P L A M; Li, S; Zuiderwijk, M; Kardos, K; Abrams, W R; Niedbala, R S; Tanke, H J

2005-04-01

470

Simplified dynamic model of a voltage-sourced converter with modular multilevel converter design  

Microsoft Academic Search

This paper introduces a simplified HVDC model developed for modeling the steady-state and the dynamic behavior of a voltage-sourced converter based on the modular multilevel converter design. The simplified model is intended for time domain simulations in a positive sequence dynamic simulation program. The model is used for dynamic stability studies and performance analysis of the HVDC within a large

Simon P. Teeuwsen

2009-01-01

471

Modeling the Trans Bay Cable Project as Voltage-Sourced Converter with Modular Multilevel Converter design  

Microsoft Academic Search

This paper introduces a model developed for modeling the steady-state and the dynamic behavior of the Trans Bay Cable Project as Voltage-Sourced Converter based on the Modular Multilevel Converter design. The model is intended for time domain simulations in an electromechanical simulation program with a balanced positive sequence network representation. Typical applications are transient stability studies and performance analysis of

Simon P. Teeuwsen

2011-01-01

472

Novel primary high voltage traction converter with single-phase matrix converter  

Microsoft Academic Search

This paper presents research motivated by industrial demand for special traction drive topology devoted to minimization of traction transformer weight against topology with classical 50Hz traction transformer. The main attention has been given to the special traction drive topology for AC power systems: input high voltage trolley converter (single phase) - middle frequency transformer (single phase) - output converter (single

DRABEK Pavel; PITTERMANN Martin

2009-01-01

473

Multi converter approach to active power filtering using current source converters  

Microsoft Academic Search

Active power filtering is performed by detecting the line current and voltage signals, generating a current equal-but-opposite to the distortion current using a power converter and injecting the compensating current into the power line. In such applications, it is desirable to combine high power and high switching frequency while minimizing the losses. This asks for special converter topologies and control

Ramadan El Shatshat; Mehrdad Kazerani; M. M. A. Salama

2001-01-01

474

Electrodes For Alkali-Metal Thermoelectric Converters  

NASA Technical Reports Server (NTRS)

Combination of thin, porous electrode and overlying collector grid reduces internal resistance of alkali-metal thermoelectric converter cell. Low resistance of new electrode and grid boosts power density nearly to 1 W/cm2 of electrode area at typical operating temperatures of 1,000 to 1,300 K. Conductive grid encircles electrode film on alumina tube. Bus wire runs along tube to collect electrical current from grid. Such converters used to transform solar, nuclear, and waste heat into electric power.

Williams, Roger M.; Wheeler, Bob L.; Jeffries-Nakamura, Barbara; Lamb, James L.; Bankston, C. Perry; Cole, Terry

1989-01-01

475

Quasi-resonant converters - Topologies and characteristics  

NASA Astrophysics Data System (ADS)

In designing switching dc-dc converters, the effort to increase operating frequency to reduce weight, size, and cost of magnetic and filter elements is constantly hampered by higher switching stresses and switching losses. To overcome these obstacles, the concept of the 'resonant switch' is proposed. By incorporating additional inductor and capacitor elements to shape the semiconductor switch's current waveform, a 'zero-current switching' property can be realized. Based on the resonant switch technique, a new host of quasi-resonant converter circuits have been derived, which can be operated in the megahertz range.

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

1987-01-01

476

Solar energy converter using surface plasma waves  

NASA Technical Reports Server (NTRS)

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.

Anderson, L. M. (inventor)

1984-01-01

477

New strategy for optimizing wavelength converter placement.  

PubMed

This paper proposes a new strategic alternate-path routing to be combined with the particle swarm optimization (PSO) algorithm to better solve the wavelength converters placement problem. The strategic search heuristic is designed to provide network connectivity topologies for the converters to be placed more effectively. The new strategy is applied to the 14-node NSFNET to examine its efficiency in reducing the blocking probability in sparse wavelength conversion network. Computed results show that, when applied to the identical optimization framework, our search method outperforms both the equal-cost multipath routing and traffic-engineering-aware shortest-path routing. PMID:19488383

Foo, Y; Chien, S; Low, Andy; Teo, C; Lee, Youngseok

2005-01-24

478

Combination solar photovoltaic heat engine energy converter  

NASA Astrophysics Data System (ADS)

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.

Chubb, Donald L.

1987-08-01

479

Convertible calls and corporate taxes under asymmetric information  

Microsoft Academic Search

This paper develops a signalling model of call of convertible securities (bonds or preferred stock) in the presence of corporate taxes and asymmetric information about future earnings. In equilibrium, managers with relatively unfavorable information call to force convertible holders to convert to common stock (in spite of the loss of corporate tax benefits if the convertibles are bonds), while those

Yong O. Kim; Jarl Kallberg

1998-01-01

480

A simple and efficient implemantation of interleaved boost converter  

Microsoft Academic Search

Recently, DC-DC boost converters are usually required in many applications which has low output voltage, such as renewable energy sources. The interleaved boost converters consists of several identical boost converters connected in parallel and controlled by the interleaved method which has the same switching frequency and phase shift. The advantages of interleaved boost converters include increased efficiency, reduced size and

Nasir Coruh; Satilmis Urgun; Tarik Erfidan; Semra Ozturk

2011-01-01

481

A new Mixed Stacked Multicell converter with Interesting Advantages  

Microsoft Academic Search

Multilevel converters are very interesting alternatives for medium and high power applications. This paper presents a new configuration of multicell converters. The main advantages of the proposed converter, in comparison with conventional Flying Capacitor Multicell (FCM) and Stacked Multicell (SM) converters, are doubling the number of output voltage levels and the RMS, improving the output voltage frequency spectrum and lowering

Meisam Sadeghi; Seyed Hossein Hosseini; Mohammad Nilkar

2011-01-01

482

Effect of FET output capacitance on ZVS of resonant converters  

Microsoft Academic Search

The analysis of resonant converters including the capacitance of the switches is presented. New dc characteristics are obtained for the series, parallel, and series-parallel resonant converters (SPRC). The operating regions where the converters operate with zero-voltage switching (ZVS) are determined as a function of the switch capacitance. The more pronounced effect can be seen in the series resonant converter (SRC),

J. A. Sabate; R. W. Farrington; M. M. Jovanovic; E. C. Lee

1996-01-01

483

Optical wavelength converters: techniques and system aspects  

NASA Astrophysics Data System (ADS)

Optical wavelength conversion will be a key function in photonic networks. Therefore the development of effective and practical all-optical wavelength converters is subject to considerable attention. Here, the application is outlined and the performance of wavelength conversion by semiconductor optical amplifiers reviewed.

Joergensen, Carsten; Danielsen, Soren L.; Mikkelsen, Benny; Stubkjaer, Kristian E.; Vodjdani, Nakita; Ratovelomanana, F.; Enard, Alain; Glastre, Genevieve; Rondi, D.; Blondeau, Robert R.; Doussiere, P.; Garabedian, G.; Graver, C.; Jourdan, Amaury; Schilling, Michael; Idler, Wilfried; Wunstel, K.

1996-03-01

484

Power electronics converters for wind turbine systems  

Microsoft Academic Search

The steady growth of installed wind power which reached 200 GW capacity in 2010, together with the up-scaling of the single wind turbine power capability - 7 MW's has been announced by manufacturers - has pushed the research and development of power converters towards full scale power conversion, lowered cost pr kW, and increased power density and the need for

F. Blaabjerg; M. Liserre; K. Ma

2011-01-01

485

Active harmonic elimination for multilevel converters  

Microsoft Academic Search

This paper presents an active harmonic elimination method to eliminate any number of specific higher order harmonics of multilevel converters with equal or unequal dc voltages. First, resultant theory is applied to transcendental equations characterizing the harmonic content to eliminate low order harmonics and to determine switching angles for the fundamental frequency switching scheme and a unipolar switching scheme. Next,

Zhong Du; L. M. Tolbert; J. N. Chiasson

2006-01-01

486

Comparison of multilevel converter-based STATCOMs  

Microsoft Academic Search

Multilevel converters have become the real option for high voltage and current applications for power systems, especially for FACTS controllers. The Static Compensator (STATCOM) is a shunt-type device which can be used to control reactive power in a network as of its many advantages such as fast speed, compact footprint and small harmonics. In this work a comparison between two

J. H. Vivas; G. Bergna; M. Boyra

2011-01-01

487

Thermal neutron detection with 6Li converters  

Microsoft Academic Search

In this detector research and development the key product is a 100 mum thin 6Li metal foil, which is to be used as converter for neutron detection. Due to the chemical reactivity of metallic lithium a special treatment is required for fabrication of such foils. Preparation by rolling lithium in a glove box, protection with ultra thin polymer films against

R. Engels; G. Kemmerling; H. Noldgen; J. Schelten

2007-01-01

488

Power electronic converters for switched reluctance drives  

Microsoft Academic Search

A number of power electronic converter circuits exist for switched reluctance motor (SRM) drives which are generally applicable to most loads. A larger number of circuits exist which are suitable for particular niche applications, but which have the potential to be the most cost-effective within that niche. Due to the variable methods of operation of these circuits and the rapid

Mike Barnes; Charles Pollock

1998-01-01

489

Catalytic Converters Maintain Air Quality in Mines  

NASA Technical Reports Server (NTRS)

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.

2014-01-01

490

Converting Your Lab from Verification to Inquiry  

NSDL National Science Digital Library

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.

Russell, Connie P.; French, Donald P.

2006-01-01

491

A Java Card CAP converter in PVS  

Microsoft Academic Search

Abstract: The Java Card language is a trimmed down dialect of Java aimed at programmingsmart cards. Java Card species its own classle format (the Java Card ConvertedAPplet (CAP) format) that is optimised with respect to the limited space resourcesof smart cards. This paper deals with the certied development of algorithms necessaryfor the conversion of ordinary Java classles into the CAP

Thomas Genet; Thomas P. Jensen; Vikash Kodati; David Pichardie

2003-01-01

492

Photothermoelectric converter: A new design concept  

NASA Astrophysics Data System (ADS)

A new concept of the photothermoelectric converter (PTEC) is proposed, which is free of the main disadvantages (overheating of the photocell and insufficient heat flux in the thermocell) of the existing schemes. The problems are solved using a PTEC scheme with a narrowband optical filter, which transmits radiation with the optimum spectrum to the photocells and directs optimum heat flux to the thermocell.

Iordanishvili, E. K.

2006-12-01

493

Converting Calcium Sulphide to Calcium Oxide.  

National Technical Information Service (NTIS)

CaS is converted to CaO with increased production of SO2 and decreased production of CaSO4 by passing CaS-containing particles into one region of a conversion bed wherein they are fluidized at an elevated temperature by an upwardly-passing oxygen-containi...

G. Moss

1978-01-01

494

State equations based resonant converters modeling technique  

Microsoft Academic Search

State equations for resonant converters are developed by using orthogonal circuit synthesis. Low frequency state variables are selected for the resonant circuit, such as envelopes of resonant inductor current and resonant capacitor voltage, phase angle between inverter output voltage and output current. For a given resonant tank, its orthogonal counterpart is constructed. These two orthogonal tanks are combined into a

Yingqi Zhang; P. C. Sen

2010-01-01

495

Adaptive PI Stabilization of Switched Power Converters  

Microsoft Academic Search

Linear proportional-integral (PI) controllers are widely used in power converter applications. In a recent paper, a methodology to design such controllers ensuring asymptotic stability was proposed. The technique relied on the basic fact that if an affine system can be rendered passive with a constant control, then it is stabilizable with a PI. A structural condition was imposed then on

Michael Hernandez-Gomez; Romeo Ortega; Françoise Lamnabhi-Lagarrigue; Gerardo Escobar

2010-01-01

496

Power converter for wind turbine application  

Microsoft Academic Search

Variable speed wind turbines are known to provide more effective power capture than their fixed-speed counterparts. To generate electrical power over a wide range of speeds, induction generators have been shown to be superior in many ways to DC generators: efficiency, maintainability, power density, etc. Unfortunately, loads are typically fixed-frequency. A power electronic converter enables efficient conversion of the variable

Herbert L. Hess; Noor A. Abdul Melek; E. Muljadi

2000-01-01

497

Signal folding in A\\/D converters  

Microsoft Academic Search

Signal folding appears in A\\/D converters (ADCs) in various ways. In this paper, the evolution of this technique is derived from the fundamentals of quantization to obtain systematic insights. We look upon folding as an automatic multiplexing of zero crossings, which simplifies hardware while preserving the high speed and low latency of a flash ADC. By appreciating similarities between the

Hui Pan; Asad A. Abidi

2004-01-01

498

Sea and ocean wave energy converter  

Microsoft Academic Search

A device for converting the energy of sea and ocean waves is described, including a turbogenerator connected by means of pipelines to input and output elements on which there are mounted ballast systems and stabilizers. The input and output elements are designed as a high pressure vessel and a low pressure vessel, respectively, each having a gas cushion. A high

Nedyalkov

1982-01-01

499

Design of a Meteorological Facsimile Converter.  

National Technical Information Service (NTIS)

The facsimile transmission of weather maps and charts which are of use, for example, to sea farers, is presented. The design of a Meteorological Facsimile Converter (MFC) is detailed. The input of the MFC would be the facsimile signal received by an exter...

A. W. Andrews

1990-01-01

500

Multiterminal Operation of HVDC Converter Stations  

Microsoft Academic Search

In the present stage of HVDC transmission technique, future applications may be outlined for which a multiterminal operation of HVDC converter stations would appear necessary or desirable. Simple problems, such as tapping of an HVDC transmission, can be solved by means of the known control and protection methods of the two-terminal operation. An unrestricted multiterminal operation, however, involves a number

Reiner Foerst; Gerhard Heyner; Karl Kanngiesser; Hermann Waldmann

1969-01-01