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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

A Dual Supply Buck Converter with Improved Light Load Efficiency  

E-print Network

, portable devices are operating under light load condition for the most of the time. Conventional buck converters suffer from low light-load efficiency which severely limits battery lifetime. In this project, a novel technique for buck converter is proposed...

Chen, Hui

2013-05-02

5

Design optimization of coupled inductor multiphase synchronous buck converter  

Microsoft Academic Search

In this paper a detailed design optimization technique for multiphase synchronous buck converters is discussed. As the voltage regulator modules (VRMs) for future microprocessors require power delivery at high frequency, low voltage and high current, it is shown that, coupled inductor technique is well suited. As there is no method existing to pre estimate the losses and hence the efficiency

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

2005-01-01

6

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

E-print Network

Improvement in battery life Low voltage Single cell operation (Li-ion/NiCd/NiMH/Fuel Cell) Integrated voltage depending on work- load/throughput to extend battery life. Single inductor, non-inverting buck-boost converters are best-suited to generate a voltage that is higher and lower than the battery supply

Rincon-Mora, Gabriel A.

7

Buck quasi-resonant converter operating at constant frequency: analysis, design, and experimentation  

Microsoft Academic Search

A buck pulsewidth modulated zero-current switching quasi-resonant converter (buck PWM ZCS QRC) operating at constant frequency is discussed. Operating principle and design-oriented analysis are presented with normalized design curves, design procedure, design example, simulations, and experimental results. The new topology, which can be considered as a particular one, is compared with the well-established buck frequency-modulated zero-current switching quasi-resonant converter (buck

I. Barbi; J. C. O. Bolacell; D. C. Martins; F. B. Libano

1990-01-01

8

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

9

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

E-print Network

to the switching losses that do not scale with load current. In this research, a novel technique for buck converter is proposed to reduce the switching loss by reducing the effective voltage supply at light load. This buck converter, implemented in TSMC 0...

Zhang, Chao

2012-07-16

10

Investigation of Multiphase Coupled-Inductor Buck Converters in Point-of-Load Applications.  

E-print Network

??Multiphase interleaving buck converters are widely used in todayâs industrial point-of-load (POL) converters, especially the microprocessor voltage regulators (VRs). The issue of todayâs multiphase interleaving… (more)

Dong, Yan

2009-01-01

11

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

NASA Technical Reports Server (NTRS)

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

Schoenfeld, A. D.; Yu, Y.

1973-01-01

12

Buck quasi-resonant converter operating at constant frequency: analysis, design and experimentation  

Microsoft Academic Search

Consideration is given to a buck zero-current-switching quasi-resonant converter (buck-PWM-ZCS-QRC) operating at constant frequency. Operation principle and design-oriented analysis are presented, with normalized design curves, design procedure, design example, simulations, and experimental results. The new topology is compared with the well-established Buck-FM-ZCS-QRC proposed by F.C. Lee (Proc. IEEE, vol.76, Apr.1988), which can be considered as a particular topology

I. Barbi; J. C. Bolacell; D. C. Martins; F. B. Libano

1989-01-01

13

Design of zero-current-switching fixed frequency boost and buck converters with coupled inductors  

Microsoft Academic Search

A boost power converter and a buck power converter are introduced in this paper. The input\\/output current can be made continuous with extra low ripple using a coupled inductor. Configurations and control strategy for this type of power converter are quite simple. This type of converter has been analyzed by using the MICROTRAN (EMTP) simulation package

Jing Wang; William G. Dunford; Konrad Mauch

1995-01-01

14

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

E-print Network

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

King, Charles Jackson, III

2009-01-01

15

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

E-print Network

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

Whitaker, Michael Peter

2007-01-01

16

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

Microsoft Academic Search

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

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

2008-01-01

17

Multi-phase buck converter design with two-phase coupled inductors  

Microsoft Academic Search

Ever increasing demand for higher current, lower voltage and faster dynamic response imposes a challenge for multi-phase buck converter designs. Coupling the output inductors of multi-phase buck has the potential to reduce steady-state power losses while maintaining or even improving dynamic performance. Two-phase coupled inductors take advantage of magnetic coupling, have a physically symmetrical structure and with identical magnetic characteristics,

Wenkai Wu; Nai-Chi Lee; George Schuellein

2006-01-01

18

PWM Technique for Non-Isolated Three-Phase Buck-Boost PFC Converter  

NASA Astrophysics Data System (ADS)

The buck-boost power factor corrected (PFC) converter has the wide range of the dc output voltage. A new non-isolated three-phase hard-switching and a soft-switching buck-boost PFC converter are proposed. Removing the three-phase transformer from the converters makes their size more compact and their costs lower. In addition, the new control method based on the PWM technique is proposed in this paper to achieve the high power factor. Complete soft-switching is also achieved under the discontinuous current mode (DCM) operation.

Morizane, Toshimitsu; Shimomori, Wataru; Taniguchi, Katsunori; Kimura, Noriyuki; Ogawa, Masanori

19

An enhanced double current limit technique used in high power BUCK converter  

Microsoft Academic Search

An enhanced double current limit technique suitable for high power buck converter is presented in this paper to protect the converter from damage under any fault condition. The first peak current limit circuit works properly when the output is in minor over load. If the current increases continuously to some amount after the first peak current limit working in major

Zekun Zhou; Zhi Huang; Xing Ming; Bo Zhang; Zhaoji Li

2009-01-01

20

Current Mode Control Integrated Circuit with High Accuracy Current Sensing Circuit for Buck Converter  

Microsoft Academic Search

A current mode control integrated circuit with accuracy current sensing circuit ( CSC ) for buck converter is presented in this the proposed accurate integrated current sensed inductor with the internal ramp be used for DC-DC converter feedback proposed CSC doesn't need an op amp to implement, and has been fabricated with a standard 0.35 mum CMOS process. Simulation result

Chih-Jen HsuandY; Y. S. Lee

2007-01-01

21

A self powered gate drive circuit for tapped inductor buck converter  

Microsoft Academic Search

This paper proposes a new recovering approach for a tapped inductor buck converter. In the proposed converter, the energy of the leakage inductance is transferred into two capacitors. The capacitors behave like constant power supplies for gate-driver circuits. A voltage source driver is used for driving the high-side MOSFET. For this MOSFET, the optimal design involves a tradeoff between switching

M. H. Vafaie; E. Adib; H. Farzanehfard

2012-01-01

22

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

E-print Network

Soft-Switching Buck Converter With Coupled Inductor Lei Jiang, Chunting Chris Mi, Siqi Li, Chengliang buck converter, the proposed converter added a small inductor, a diode, and an inductor coupled and the efficiencies are also measured to validate the proposed topology. Index Terms--Buck converter, coupled inductor

Mi, Chunting "Chris"

23

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

24

Boost Converter with Coupled Inductors and Buck-Boost Type of Active Clamp  

Microsoft Academic Search

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

T.-F. Wu; Y.-S. Lai; J.-C. Hung; Y.-M. Chen

2005-01-01

25

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

26

A novel zero voltage switched (ZVS) buck converter using coupled inductor  

Microsoft Academic Search

A novel zero-voltage switched (ZVS) buck converter using a coupled inductor is proposed in this paper. An additional winding is added on the same core of the output filter inductor for the purpose of commutation. The output inductor current is kept in continuous conduction mode (CCM) with small ripple. ZVS conditions for both switches are satisfied over wide load range.

Yingqi Zhang; P. C. Sen; Yan-Fei Liu

2001-01-01

27

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

E-print Network

Regenerative Braking for an Electric Vehicle Using Ultracapacitors and a Buck-Boost Converter Juan situation (regenerative braking), the battery voltage goes up, and then the control needs to activate regenerative braking can be avoided #12;with the help of ultracapacitors. Besides, ultracapacitors allow

Catholic University of Chile (Universidad Católica de Chile)

28

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

Microsoft Academic Search

An ultracapacitor bank control system for an Electric Vehicle has been simulated. The purpose of this device is to allow higher accelerations and decelerations of the vehicle with minimal loss of energy, and minimal degradation of the main battery pack. The system uses an IGBT Buck-Boost converter, which is connected to the ultracapacitor bank at the Boost side, and to

Juan W. Dixon; Micah Ortúzar; Eduardo Wiechmann

29

Grazing, skipping and sliding: analysis of the nonsmooth dynamics of the DC/DC buck converter  

E-print Network

Grazing, skipping and sliding: analysis of the non­smooth dynamics of the DC/DC buck converter of its dynamical behaviour. We then introduce the so­called grazing and sliding solutions and discuss is studied which explains how the grazing bifurcations cause sharp turning points in the bifurcation diagram

Bath, University of

30

A new low-stress buck-boost converter for universal-input PPC applications  

Microsoft Academic Search

In converters for power-factor-correction (PFC), universal-input capability (ability to operate from any AC line voltage, world-wide) comes with a heavy price in terms of component stresses and losses, size of components, and restrictions on the output DC voltage. A new two-switch topology is proposed to offer very significant performance improvements over the single-switch buck-boost converters (including flyback, SEPIC, and Cuk

Jingquan Chen; Dragan MaksimoviC; Robert Erickson

2001-01-01

31

Advanced buck converter power supply ABCPS for APT  

SciTech Connect

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

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

1998-12-31

32

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

33

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

34

An interleaving double-switch Buck-Boost converter for PV grid-connected inverter  

Microsoft Academic Search

Characterized with noninverting and step-up\\/step-down conversion, the double-switch Buck-Boost converter is suit for the front stage of the two-stage PV grid-connected inverter. But, the large inductor is required in conventional control strategy, and the sophisticated control logic and difficult compensation technique for smooth transitions are included in combined control strategy. In order to reduce the inductor and simplify the control

Huafeng Xiao; Shaojun Xie; Wenming Chen; Ruhai Huang

2010-01-01

35

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

36

Design of Low Power Monolithic DC-DC Buck Converter with Integrated Inductor  

Microsoft Academic Search

This paper presents the design and fabrication of monolithic buck converter using standard CMOS process. As the Q-factor of planar spiral inductor is low in standard CMOS process, this work uses an in-plane inductor built using a CMOS compatible MEMS based technique called PDMA (plastic deformation magnetic assembly). The fabrication process for integrating this air-core, in-plane PDMA inductor is outlined.

Surya Musunuri; Patrick L. Chapman

2005-01-01

37

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

38

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

E-print Network

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

Schrock, Kenneth C

2008-01-01

39

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

E-print Network

MHz is demonstrated for a voltage conversion from 1.2 volts to 0.9 volts while supplying 9.5 amperesEfficiency Analysis of a High Frequency Buck Converter for On-Chip Integration with a Dual converter is presented in this paper. A high switching frequency is the key design parameter

Friedman, Eby G.

40

Analysis and design of a three-phase reduced switch buck-boost ac-dc converter  

Microsoft Academic Search

A simple, low-cost, reduced-switch, three-phase ac- dc buck-boost converter is proposed in this paper. The converter can operate with input power factor correction and is suitable for applications where a converter needs to operate over a wide range of input ac voltages and\\/or produce a wide range of output dc voltages. In the paper, the converter's operation is explained and

Dunisha Wijeratne; Gerry Moschopoulos

2011-01-01

41

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

42

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--I: FUNDAMENTAL THEORY AND APPLICATIONS, VOL. 45, NO. 7, JULY 1998 707 BorderCollision Bifurcations in the Buck Converter  

E-print Network

for the logistic map f(x) = x(1 0 x). (b) A portion of the bifurcation diagram for the buck converter discussed, JULY 1998 707 Border­Collision Bifurcations in the Buck Converter Guohui Yuan, Soumitro Banerjee, Edward Ott, and James A. Yorke Abstract--Interesting bifurcation phenomena are observed for the current

Yorke, James

43

Analysis of a voltage controlled frequency foldback technique that improves short circuit protection for buck derived converters  

Microsoft Academic Search

The output VI characteristics of most high frequency buck-derived PWM power converters exhibit a current tail during fault conditions. A current tail is actually an increase in the average output current as the output voltage decreases toward zero. Ideally, the controller's peak current limit function should prevent the average output current from exceeding a specified limit. In reality, the tail

Philip Cooke

1996-01-01

44

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

45

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. PMID:24854061

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

2014-01-01

46

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

PubMed

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

Komurcugil, Hasan

2012-11-01

47

An exact tracking error dynamics passive output feedback controller for a Buck-Boost-converter  

E-print Network

,hsira,rsilva}@cinvestav.mx Institute of Automation and Control (EIT 8.1) Faculty of Electrical Engineering and Information Technology in the design of feedback control laws [2], [3], [4]. The main idea behind the design methods is to deviseAn exact tracking error dynamics passive output feedback controller for a Buck

Knobloch,Jürgen

48

Using coupled inductors to enhance transient performance of multi-phase buck converters  

Microsoft Academic Search

Motivated by modern microprocessors' demand for high-current, low-voltage power with large transient load steps, a scalable multi-phase coupled inductor buck circuit is presented which delivers 80 A at 1.2 V from a 12 V input. 4-phase coupling and 1 MHz per-phase switching frequency enable the use of 50 nil per-phase leakage inductance so that the system is capable of supporting

Jieli Li; Anthony Stratakos; Aaron Schultz; Charles R. Sullivan

2004-01-01

49

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

NASA Astrophysics Data System (ADS)

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

Dimopoulos, Emmanouil; Munk-Nielsen, Stig

2014-03-01

50

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

51

Analysis of a Smith-predictor-based-control concept eliminating the right-half plane zero of continuous mode boost and buck-boost DC\\/DC converters  

Microsoft Academic Search

It is pointed out that the small-signal transfer function of a boost or a buck-boost converter shows a zero located in the right-half complex plane for continuous operation. This zero makes the stabilization of the system considerably difficult. The authors use a boost converter as an example to show that application of the principle of linear prediction (as originally proposed

Felix A. HIMMELSTOSS; J. W. Kolar; Frant C. ZACH

1991-01-01

52

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

E-print Network

battery with its energy-dense counterpart like the fuel cell (FC) improves micro-scale integration a 0.6V FC and a 2.7-4.2V Li Ion battery to supply a 1V load and recharge, when unloaded, the Li Ion1 26.2 Single-Inductor Dual-Input Dual-Output Buck-Boost Fuel Cell-Li Ion Charging DC-DC Converter

Rincon-Mora, Gabriel A.

53

Bond graph modelling and dynamic study of a photovoltaic system using MPPT buck-boost converter  

Microsoft Academic Search

Photovoltaic systems are composed of several elements as PV source, DC\\/DC or DC\\/AC converters, DC or AC machines, accumulators, pumps, fans, and refrigerators. These systems are therefore of hybrid type and their modelling is complex. This is why we used the bond graph methodology. The photovoltaic generator is a special source of finite energy with a non-linear current-voltage characteristic. Thus,

R. Andouisi; A. Mami; G. Dauphin-Tanguy; M. Annabi

2002-01-01

54

A wide load range, multi-mode synchronous buck DC—DC converter with a dynamic mode controller and adaptive slope compensation  

NASA Astrophysics Data System (ADS)

A synchronous buck DC—DC converter with an adaptive multi-mode controller is proposed. In order to achieve high efficiency over its entire load range, pulse-width modulation (PWM), pulse-skip modulation (PSM) and pulse-frequency modulation (PFM) modes were integrated in the proposed DC—DC converter. With a highly accurate current sensor and a dynamic mode controller on chip, the converter can dynamically change among PWM, PSM and PFM control according to the load requirements. In addition, to avoid power device damage caused by inrush current at the start up state, a soft-start circuit is presented to suppress the inrush current. Furthermore, an adaptive slope compensation (SC) technique is proposed to stabilize the current programmed PWM controller for duty cycle passes over 50%, and improve the degraded load capability due to traditional slope compensation. The buck converter chip was simulated and manufactured under a 0.35 ?m standard CMOS process. Experimental results show that the chip can achieve 79% to 91% efficiency over the load range of 0.1 to 1000 mA

Chunhong, Zhang; Haigang, Yang; Shi, Richard

2013-06-01

55

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

56

Analysis and experimental study of the buck, boost and buck-boost inverters  

Microsoft Academic Search

In this paper, the analysis and experimental study of three kinds of inverters are presented, beginning with the traditional full bridge buck inverter, followed by two different inverter approaches, the boost and buck boost ones. This last two converters have the property of produce an output voltage higher or lower than the input voltage additionally to its inversion capability, which

N. Vazquez; J. Almazan; J. Alvarez; C. Aguilar; J. Arau

1999-01-01

57

A green-switch controller IC for cascade buck–boost converter with seamless transition over entire input and load range  

Microsoft Academic Search

To raise the utilization ratio of lithium-ion battery in portable devices, a novel green-switch controller IC is proposed to constitute a 4-switch cascade buck–boost prototype, which is capable of outputting non-inverting step down and step up voltages. According to the relations between the input and output voltages through duty ratio, a finite state machine automatically determines the work method of

Jia-Na Lou; Xiao-Bo Wu; Meng-Lian Zhao; Xiao-Lang Yan

2011-01-01

58

Peak power tracking for a solar buck charger  

E-print Network

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

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

2010-01-01

59

Design Considerations for High Step-Down ratio Buck Regulators  

E-print Network

The buck or step-down DC-DC converter is the workhorse switching power supply topology. It utilizes two switches (two FETS or one FET and one diode) along with an output inductor and output capacitor. Whether you look at a large computer server, a personal desktop or a laptop computer, a cell phone or a GPS unit all will contain a buck converter in one form or another. This paper will discuss the synchronous buck topology, design considerations, component selection followed by a small signal model of buck converter. Issues that are important in optimizing the efficiency of the design for example MOSFET selection, the impact that the MOSFET driver plays in improving the efficiency will be examined. The paper will finish by contrasting various control architectures.

Khanna, R

2008-01-01

60

Fig. 1. A digitally-controlled buck converter with the self-tuning current Self-Tuning Digital Current Estimator for Low-Power  

E-print Network

complexity is shown. Besides a simple digital IIR filter and a load step circuit, it only requires a slow overload conditions [1]. It is often utilized for increasing converter efficiency through multi CMOS digital processes. This is due to very limited supply voltages of standard digital circuits (often

Prodiæ, Aleksandar

61

An Integrated Four-Phase Buck Converter Delivering 1A/mm2 700ps Controller Delay and Network-on-Chip Load in 45-nm SOI  

E-print Network

granularity of voltage and frequency domains, for example, individually optimizing the power consumption operating point. The converter switches at 80MHz and delivers 1A/mm2 at 83% efficiency and 0.66 conversion as it is now common for the thermal envelope to limit computational performance of an IC. Dynamic voltage

Carloni, Luca

62

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

63

Single Inductor Dual Output Buck Converter  

E-print Network

and PDA's. With advancement in technology and more intelligent processors being used, there is a need for multiple high integrity voltage supplies for empowering the systems in portable electronic devices. Switched mode power supplies (SMPS's) are used...

Eachempatti, Haritha

2010-07-14

64

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

65

[Gynecomastia in a goat buck].  

PubMed

A 3-year old horned buck of the Toggenburger breed was referred to our clinic with signs of gynecomastia. Cytogenetic abnormalities could not be detected in the karyogram and compared to control animals the buck had normal plasma concentrations of testosterone and estradiol but not prolactin. Hyperprolactinemia has been considered the cause of gynecomastia leaving the semen quality undisturbed. PMID:8623044

Janett, F; Stöckli, A; Thun, R; Nett, P

1996-01-01

66

A Nonisolated ZVS Asymmetrical Buck Voltage Regulator Module With Direct Energy Transfer  

Microsoft Academic Search

This paper presents a new nonisolated asymmetrical buck voltage regulator module. A transformer is used to extend the extremely low duty cycle of a conventional buck converter. Turn-off losses can be significantly reduced due to the extension of duty cycle, and there are no turn-on losses owing to the zero-voltage turn-on condition. At the same time, the voltage stress over

Zhiliang Zhang; Wilson Eberle; Yan-Fei Liu; Paresh C. Sen

2009-01-01

67

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

68

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

69

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

70

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

71

Modelling, analyses and design of switching converters  

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

72

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

73

Landowners lead successful Buck Creek restoration  

E-print Network

of the watershed, according to Dr. John Sij, retired agronomist and former project leader at the Vernon center. ?#31;is e#27;ort veri#25;ed that bacteria levels periodi- cally reach problematic levels,? he said. Landowners lead successful Buck Creek... of the watershed, according to Dr. John Sij, retired agronomist and former project leader at the Vernon center. ?#31;is e#27;ort veri#25;ed that bacteria levels periodi- cally reach problematic levels,? he said. Landowners lead successful Buck Creek...

Boutwell, Kathryn S.

2012-01-01

74

A Novel Converter for Fuel-Cells Applications  

Microsoft Academic Search

The paper presents a new buck-boost converter for fuel-cell applications. The active switches in the new converter are turned-on with zero-current and zero-voltage switching and turned-off with zero-voltage switching. Neither the converter experiences any over voltage\\/overcurrent stresses nor does it suffer from the zero-capacitive turn-on loss, which is present in other soft-switched converters. A steady state analysis of the converter

B. P. Divakar; D. Sutanto

2005-01-01

75

BEAR BUCKS: Beginning Fall Semester 2013, all students including students on UM Dining Meal Plans, will have access to the Bear Bucks Program. Bear Bucks is a declining balance account offering campus-wide  

E-print Network

., Missoula College, and includes $100 in Bear Bucks for greater campus-wide dining flexibility. Bear BucksBEAR BUCKS: Beginning Fall Semester 2013, all students including students on UM Dining Meal Plans-wide dining flexibility. New Bear Bucks accounts can be opened with as little as $20! FEATURES OF BEAR BUCKS

Chu, Xi

76

A 1MHz High-Efficiency 12-V Buck Voltage Regulator With a New Current-Source Gate Driver  

Microsoft Academic Search

This paper proposes a new current-source gate drive circuit for a synchronous buck converter. The proposed driver can drive two MOSFETs independently with different drive currents for optimal design. For the control MOSFET, the optimal design involves a tradeoff between switching loss reduction and drive circuit loss; while for the synchronous-rectifier MOSFET, the optimal design involves a tradeoff between body

Zhiliang Zhang; Wilson Eberle; Ping Lin; Yan-Fei Liu; Paresh C. Sen

2008-01-01

77

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

78

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

79

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

NASA Technical Reports Server (NTRS)

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

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

1980-01-01

80

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

Microsoft Academic Search

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

Biranchinath Sahu; Gabriel A. Rincón-mora

2005-01-01

81

Switched Coupled-Inductor Cell for DC-DC Converters with Very Large Conversion Ratio  

Microsoft Academic Search

A novel switching structure formed by an externally controlled switch, a coupled inductor, and two synchronous switches (diodes) is proposed. The practical implications of the leakage inductance are considered. This structure is inserted into PWM DC-DC buck, boost, and buck-boost converters by replacing their switch and inductor. The results are new converters with very high step-up or step-down voltage gain.

Boris Axelrod; Yefim Berkovich; A. Ioinovici

2006-01-01

82

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

83

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

84

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

E-print Network

Water Quality Monitoring in the Buck Creek Watershed and Facilitation of Buck Creek Watershed Partnership: Final Report Lucas Gregory, Texas Water Resources Institute Phyllis Dyer, Texas A&M AgriLife Research Kevin Wagner, Texas Water Resources.... Lucas Gregory and Phyllis Dyer served as principle authors. Drs. Kevin Wagner and Paul DeLaune were the principle investigators for this project. We would like to extend a special thanks to members of the Hall-Childress Soil and Water...

Gregory, L.; Dyer, P.

85

Current protections modelisation in a buck cell  

Microsoft Academic Search

Two modes of current protection and their implementation in a buck switching cell with input filter are presented. For one mode, (overloading or short circuit), the input current is maintained constant. For the other mode the output current is maintained constant. These two modes are satisfied with analog circuitry which highlights the effect of the current or voltage threshold stop

A. Barnaba

1989-01-01

86

Buck CreekWatershed Protection Plan  

E-print Network

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

87

Joshua Buck Headquarters, Washington Sept. 9, 2011  

E-print Network

is the centerpiece of our human spaceflight activities for the coming years," NASA Administrator Charles Bolden saidJoshua Buck Headquarters, Washington Sept. 9, 2011 202-358-1100 jbuck@nasa.gov RELEASE: 11-294 NASA NAMES CASIS TO MANAGE SPACE STATION NATIONAL LAB RESEARCH WASHINGTON -- NASA has finalized a cooperative

88

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

ERIC Educational Resources Information Center

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

Watts, Lynette

2008-01-01

89

DC-DC converter design for battery-operated systems  

Microsoft Academic Search

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

B. Arbetter; R. Erickson; D. Maksimovic

1995-01-01

90

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

91

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

E-print Network

is the MOFSET threshold voltage, fMAX is the maximum clock frequency and is the technology dependent velocityAbstract-- The implementation of a low-voltage Zero- Voltage-Switching Quasi-Square-Wave (ZVS-QSW) buck converter capable of meeting the future challenges of low- voltage VRMs is presented

Ng, Wai Tung

92

Three phase six-switch PWM buck rectifier with power factor improvement  

NASA Astrophysics Data System (ADS)

Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, three phase six-switch PWM buck rectifier is presented which operates at nearly unity power factor and provides variable output voltage. Small size energy storing components are required depending upon switching frequency. MATLAB simulation is performed and modified Sinusoidal Pulse Width Modulation (SPWM) switching technique is used in 3kW prototype converter to demonstrate low input current THD, nearly unity displacement factor, well regulated output voltage and reduced switching losses compared to conventional SPWM.

Zafarullah Khan, M.; Mohsin Naveed, M.; Akbar Hussain, D. M.

2013-06-01

93

Power tracking for nonlinear PV sources with coupled inductor SEPIC converter  

Microsoft Academic Search

The photovoltaic (PV) generator exhibits a nonlinear i-v characteristic and its maximum power (MP) point varies with solar insolation. In this paper, a V2-based MP point tracking (MPPT) scheme is developed using a buck-boost transformation topology. Although several buck-boost transformation topologies are available we have considered here a coupled inductor SEPIC converter for experimentation. To achieve almost ripple-free array current

MUMMADI VEERACHARY

2005-01-01

94

Context-related vocalization rates of fallow bucks, Dama dama  

Microsoft Academic Search

We studied the short-term vocalization rates of fallow bucks to determine the primary recipients of the signal conveyed by these rates. We used the contexts in which groans occurred to investigate whether the signal represented an intrasexual threat or an intersexual advertisement. We found that fallow buck groaning rates were highly variable and that this variation was associated with the

Alan G. McElligott; Thomas J. Hayden

1999-01-01

95

A single-inductor dual-input dual-output buck regulator with enhanced power-delivery capability for portable battery management system  

Microsoft Academic Search

A single-inductor dual-input dual-output (SIDIDO) buck regulator is presented for simultaneously regulating a battery charging current and a output DC voltage in portable battery management system. The proposed SIDIDO converter operates in the continuous-conduction mode for relaxing the peak current stress and thus enables the converter to deliver a maximum load power of 2.2 W. Moreover, the cross regulation between

Mengmeng Du; Hoi Lee

2010-01-01

96

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

Microsoft Academic Search

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

Sanjeev Singh; Bhim Singh

2010-01-01

97

Maximum power point tracking parameter selection for higher order converters used in photovoltaic applications  

Microsoft Academic Search

Photovoltaic array needs an intermediate maximum power point trackers as their V-I characteristics are non-linear. Successful power tracking depends on the converter and its tracking parameters. The purpose of this investigation is to introduce a procedure for selection of the tracking parameters. To demonstrate the proposed approach a fourth order buck converter, belongs to higher order family, is chosen for

M. Veerachary

2009-01-01

98

Z-Source AC–AC Converters Solving Commutation Problem  

Microsoft Academic Search

A new family of Z-source ac-ac converters with buck-boost ability are proposed, including four switches single-phase structure and six switches three-phase structure. New commutation strategies for these converters are proposed and safe commutation can be achieved without snubber circuit. The commutation strategies are easily to realize by sampling only voltage signals, and two switches are always turned on, so switching

Yu Tang; Shaojun Xie; Chaohua Zhang

2007-01-01

99

36 CFR 7.73 - Buck Island Reef National Monument.  

Code of Federal Regulations, 2013 CFR

...NATIONAL PARK SYSTEM § 7.73 Buck Island Reef National Monument. (a) Extractive uses...hermit crabs (soldier crabs), seashells, corals, dead coral, sea fans, sponges and all associated reef invertebrates, plants, fruits and...

2013-07-01

100

49. Interior of launch support building, buck boost transformer at ...  

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

49. Interior of launch support building, buck boost transformer at center, view towards southwest - Ellsworth Air Force Base, Delta Flight, Launch Facility, On County Road T512, south of Exit 116 off I-90, Interior, Jackson County, SD

101

Designing an ultra low quiescent current buck switching regulator  

E-print Network

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

Gardner, John Underhill

2008-01-01

102

Successful pregnancies with directional freezing of large volume buck semen  

Microsoft Academic Search

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

H. Gacitua; A. Arav

2005-01-01

103

A Novel Buck-Boost Z-Source Rectifier  

Microsoft Academic Search

This paper presents a novel buck\\/boost Z-Source rectifier, in which an impedance network is employed to couple the rectifier main circuit to the load, thus it provides unique features that cannot be obtained in a traditional full-bridge rectifier. The Z-source rectifier can access buck or boost function without using two-stage power conversion, so it overcomes the limitations of the traditional

Yeyuan Xie; Zhaoming Qian; Xinping Ding; Fangzheng Peng

2006-01-01

104

Single-Phase Four Switches Z-Source AC-AC Converter  

Microsoft Academic Search

A new family of single-phase four switches Z-source AC-AC converter are proposed, including voltage-fed and current-fed. Compared to the traditional ac-ac converters, they have unique features: providing a larger range of output ac voltage with buck-boost, reversing or maintaining phase angle, reducing in-rush and harmonic current. A new commutation strategy for single-phase four switches Z-source AC-AC converters is proposed to

Yu Tang; Chaohua Zhang; Shaojun Xie

2007-01-01

105

Optimization of CMOS Transistors for Low Power DC-DC Converters Abstract: This paper presents analytical derivation of  

E-print Network

Optimization of CMOS Transistors for Low Power DC-DC Converters Abstract: This paper presents analytical derivation of optimum width of CMOS transistors to minimize losses in monolithic buck converters. High optimal width of CMOS transistors entails use of tapered inverter chain as gate driver. A novel

Chapman, Patrick

106

Breed and experience effect on the sexual behaviors of Damascus and Egyptian-Nubian goat bucks  

Microsoft Academic Search

This study compares the sexual behaviors of bucks from two pure breeds of goats, Damascus and Egyptian-Nubian (Zaraibi), and assesses their relationships with the pregnancy and kidding rates of their inseminated does. Twenty-three bucks (12 Damascus and 11 Egyptian-Nubian bucks) were used in this study. These bucks were either in their first season of service (N =12, with an average

R. A. Darwish; H. D. H. Mahboub

2011-01-01

107

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

108

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

109

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

110

Gynecomastia and mammary gland adenocarcinoma in a Nubian buck.  

PubMed Central

A 6-year-old Nubian buck was presented for bilateral mammary gland enlargement. Gynecomastia and mastitis were diagnosed, and bilateral mastectomy was performed. Histological examination showed mammary adenocarcinoma, active lactation, hyperplasia, and abscessation. Karyotyping showed a normal male. Clinical, therapeutic, etiologic, and epidemiologic aspects of gynecomastia and mammary gland adenocarcinoma are discussed. Images Figure 1. PMID:10495911

Wooldridge, A A; Gill, M S; Lemarchand, T; Eilts, B; Taylor, H W; Otterson, T

1999-01-01

111

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

112

buck creek water quality buckcreek.tamu.edu  

E-print Network

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

113

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

ERIC Educational Resources Information Center

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

Smith, J. David

1995-01-01

114

Eugenics Past and Present: Remembering Buck v. Bell.  

ERIC Educational Resources Information Center

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

Berson, Michael J.; Cruz, Barbara

2001-01-01

115

Bookmark Converter  

NSDL National Science Digital Library

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

Broding, Magnus.

116

High efficiency interleaved bi-directional ZVS DC-DC converter  

NASA Astrophysics Data System (ADS)

A high efficiency interleaved bi-directional ZVS DC-DC converter is presented in this paper. This converter can be operated in both buck and boost mode. CoolMOS is used as a power device to achieve low conduction losses and fast turn off. The value of inductance is selected such that the CoolMOS drain-to-source voltage always falls to zero before it turns on and ZVS is achieved. Multiphase interleaved inductors are used to achieve high power and low ripple currents. Converter is operated at 50kHz and MATLAB Simulink simulation is performed. 6kW prototype converter is implemented in buck mode and simulation results are verified.

Zafarullah Khan, M.; Mohsin Naveed, M.; Akbar Hussain, D. M.

2013-06-01

117

Active-clamp ZVS converter with step-up voltage conversion ratio  

Microsoft Academic Search

This paper presents a new isolated dc\\/dc converter with zero-voltage turn-on switching (ZVS) of power switches and zero-current turn-off switching (ZCS) of diodes. In conventional flyback converter, the main drawbacks are high voltage stresses on power devices large transformer size, and serious reverse recovery current which resulted in high voltage spike across output diode. To solve these problems, buck-boost type

B.-R. Lin; Y.-S. Huang; Chia-Yu Tung; J.-J. Chen; J.-J. Shieh

2009-01-01

118

Appearance of a RHP-zero in VSI-based photovoltaic converter control dynamics  

Microsoft Academic Search

A typical grid-connected voltage source inverter (VSI) in its simplest form consists of an input voltage source, switch matrix, output inductor and grid, which acts as a voltage type load. This arrangement yields a converter with first-order control dynamics, a buck-type converter behavior and discontinuous input current. A photovoltaic (PV) array can provide a specific maximum current depending on the

L. Nousiainen; J. Puukko; T. Suntio

2011-01-01

119

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

120

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.

2014-01-01

121

Thermionic converter  

DOEpatents

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

Fitzpatrick, G.O.

1987-05-19

122

Optimization of DC-DC Converters for Improved Electromagnetic Compatibility With High Energy Physics Front-End Electronics  

E-print Network

The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DC buck converters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buck converter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.

Fuentes, C; Michelis, S; Blanchot, G; Allongue, B; Faccio, F; Orlandi, S; Kayal, M; Pontt, J

2011-01-01

123

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

124

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

125

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

Microsoft Academic Search

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

M. T. Iqbal; J. E. Quaicoe

2006-01-01

126

Liquid Nitrogen Temperature Operation of a Switching Power Converter  

NASA Technical Reports Server (NTRS)

The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

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

1995-01-01

127

I-A Modulated Digitally Controlled Non-Inverting Buck-Boost Converter for  

E-print Network

(from 800 mV to 3.6 V) to WCDMA RF power amplifiers (RFPA) from a 2.7-5.5 V Li-Ion battery, as shown to a WCDMA RF power amplifier (RFPA) in orderto improve the system efficiency under different transmitted RF transitions in order to improve closed-loop dynamic performance. Results are verified on an experimental test

128

Flyback Transformer Based Transient Suppression Method for Digitally Controlled Buck Converters  

E-print Network

inductor [11-15] handling the maximum load current or two extra magnetically coupled inductors [16, 17 inductor is boosted to suppress voltage deviation with the help of the secondary winding of a flyback of the power switches, such that the output voltage and the inductor current are restored in a single on

Prodiæ, Aleksandar

129

A High-Efficiency, Auto Mode-Hop, Variable-Voltage, Ripple Control Buck Converter  

E-print Network

conversion is based on applying a voltage pulse (with a specific duty cycle and frequency) to a low pass-power systems that employ the DVFS (dynamic voltage and frequency scaling) technique whereby, depending on the workload of the system, the supply voltage (and correspondingly, the clock frequency) of the system

Pedram, Massoud

130

Sensorless Current Sharing in Digitally Controlled Two-Phase Buck DC-DC Converters  

E-print Network

Corradini and Dragan Maksimovic Colorado Power Electronics Center ECE Department, University of Colorado, Boulder, CO 80309-0425 {xzhang, luca.corradini, maksimov}@colorado.edu Abstract- This paper describes

131

A low voltage, dynamic, noninverting, synchronous buck-boost converter for portable applications  

Microsoft Academic Search

With the increasing use of low voltage portable devices and growing requirements of functionalities embedded into such devices, efficient power management techniques are needed for longer battery life. Given the highly variable nature of batteries (e.g., 2.7-4.2 V for Li-ion), systems often require supply voltages to be both higher and lower than the battery voltage (e.g., power amplifier for CDMA

Biranchinath Sahu; Gabriel A. Rincón-Mora

2004-01-01

132

Optimal Design of Resonant Gate Driver for Buck Converter Based on a New Analytical Loss Model  

Microsoft Academic Search

In this paper, the advantages of a new resonant driver are verified thoroughly by the analytical analysis, simulation and experimental results. A new accurate analytical loss model of the power metal oxide semiconductor field effect transistor driven by a current-source resonant gate driver is developed. Closed-formed analytical equations are derived to investigate the switching characteristics due to the parasitic inductance.

Zhiliang Zhang; Wilson Eberle; Zhihua Yang; Yan-Fei Liu; Paresh C. Sen

2008-01-01

133

Switching loss analysis considering parasitic loop inductance with current source drivers for buck converters  

Microsoft Academic Search

In this paper, the switching loop inductance was investigated on the Current Source Drivers (CSDs). The analytical model was developed to predict the switching losses. It is noted that although the CSDs can reduce the switching transition time and switching loss greatly, the switching loop inductance still has the current holding effect on the CSDs. This results in high turn

Zhiliang Zhang; Jizhen Fu; Yan-Fei Liu; P. C. Sen

2010-01-01

134

Switching Loss Analysis Considering Parasitic Loop Inductance With Current Source Drivers for Buck Converters  

Microsoft Academic Search

In this letter, the switching loop inductance was inves- tigated on the current-source drivers (CSDs). The analytical model was developed to predict the switching losses. It is noted that al- though the CSDs can greatly reduce the switching transition time and switching loss, the switching loop inductance still causes the current holding effect on the CSDs. This results in high

Zhiliang Zhang; Jizhen Fu; Yan-Fei Liu; Paresh C. Sen

2011-01-01

135

Does a prosocial-selfish distinction help explain the biological affects? Comment on Buck (1999)  

Microsoft Academic Search

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

Jeremy R. Gray

2002-01-01

136

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

E-print Network

Evaluation of SiC MOSFETs for a High Efficiency Three-Phase Buck Rectifier Fan Xu, Ben Guo, Leon M rectifier for a 400 Vdc architecture data center power supply is designed. The total loss of this rectifier is calculated full load. The results show that the SiC based buck rectifier can obtain low power loss

Tolbert, Leon M.

137

SciHadoop: Array-based Query Processing in Hadoop Joe B. Buck  

E-print Network

sets. In this paper we present SciHadoop, a system for enhancing the performance of common analysis the file system. The SWAMP[12] project has been successful in parallelizing the execution of NCO queriesSciHadoop: Array-based Query Processing in Hadoop Joe B. Buck UC Santa Cruz buck@cs.ucsc.edu Noah

Polyzotis, Neoklis (Alkis)

138

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

PubMed

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

Nagai, Ryoji; Hajima, Ryoichi; Nishimori, Nobuyuki

2012-12-01

139

FARLES PRAIRIE AND BUCK LAKE ROADLESS AREAS, FLORIDA.  

USGS Publications Warehouse

Mineral surveys of the Farles Prairie and Buck Lake Roadless Areas, Florida showed little promise for the occurrence of metallic mineral or energy resources; the possibility for the occurrence of hydrocarbons, however, cannot be ruled out. The only mineral material that has been produced in the roadless areas is clayey sand used in stabilizing roads. Limestone underlies all of the two areas, but is too far from markets and under too much overburden for quarrying. Heavy minerals and phosphate are present in the two areas but are not sufficiently concentrated to be identified as resources.

Patterson, Sam H.; Crandall, Thomas M.

1984-01-01

140

Sediment magnetic and paleomagnetic data from Buck Lake, Oregon  

USGS Publications Warehouse

Sediment magnetic and paleomagnetic studies were conducted on a core from Buck Lake, Klamath County, Oregon, that was collected as part of an investigation into the Quaternary climate history of the western United States. This report documents the methods used to obtain paleomagnetic directions, magnetic properties, and ancillary data, and presents these data in tabular form. Adam (1993) and Adam and others (1994) describe the site, the drilling methods, and lithology of the lacustrine sediments. Rosenbaum and others (1994) present preliminary interpretations of the sediment magnetic data and show that variations in magnetic properties closely reflect changes in climate as interpreted from the pollen record.

Rosenbaum, J. G.; Reynolds, R. L.; Fitzmaurice, P. L.; Drexler, J. W.; Whitney, C. G.; Adam, D. P.

1994-01-01

141

Influence of sexually inactive bucks subjected to long photoperiod or testosterone on the induction of estrus in anovulatory goats.  

PubMed

The objective of this study was to evaluate the efficacy of treating sexually inactive bucks with artificial long photoperiod or testosterone on the induction of estrus in anovulatory grazing goats. A total of 91 multiparous mixed-breed anestrous goats were randomly assigned to one of three treatment groups: (1) joining with bucks subjected to 2.5 month of artificial long days (16 h of light/day; n=31), (2) joining with testosterone-treated bucks (n=30), and (3) joining with untreated bucks (control; n=30). There were no differences between the light-treated (100%) and testosterone-treated (93%) bucks in their ability to induce estrus in anovulatory does. On the other hand, none of the goats in contact with control bucks exhibited estrus. The interval from start of mating to estrus was shorter in goats with the light-treated bucks (37.9 ± 4.8 h) compared with does in contact with testosterone-treated bucks (58.3 ± 8.7 h). The overall pregnancy rate in goats joined with light-treated, testosterone-treated and control bucks was 84%, 77% and 0%, respectively, with no difference (P>0.05) between the first two groups. Anogenital sniffing, approaches, mounting attempts, and mounts were highest (P<0.01) in light-treated bucks and lowest in control bucks. It was concluded that testosterone-treated bucks and long-day-treated bucks were equally effective in synchronizing estrus in anovulatory goats and resulted in similar levels of fertility. Given that light-treated bucks are unviable in communal production systems of goats raised by resource-poor farmers, the sexual arousal of bucks with testosterone is a practical and reliable method to induce ovulation in anovulatory goats in pastoral goat systems in hot environments. PMID:21655923

Luna-Orozco, Juan Ramón; Guillen-Muñoz, Juan Manuel; De Santiago-Miramontes, Ma de los Angeles; García, José Eduardo; Rodríguez-Martínez, Rafael; Meza-Herrera, Cesar Alberto; Mellado, Miguel; Véliz, Francisco Gerardo

2012-01-01

142

Interpreted reflection seismic events near the North Central Corporation well, Newark basin, Bucks County, Pennsylvania  

SciTech Connect

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. Although the drill hole was abandoned, it revealed excellent gas shows throughout the Lockatong Formation and parts of the Stockton Formation. Acoustic and density logs from the well were converted to a synthetic seismogram that ties stratigraphic intervals in the borehole with seismic events on the nearby, 33-mi-long Seitel ND-1 seismic line. Formation contacts, probable intraformational unconformities and lithologic units such as 50-ft-thick fluvial sandstones in the Stockton Formation are identified and traced for tens of miles away from the well. Moreover, beneath the drill site in the Stockton Formation, the 48-fold seismic line shows a large anticline that is subparallel to the border fault. The anticline has no surface expression; but, in combination with the intersecting Revere Anticline, provides an obvious exploration target. The authors interpretation suggests that the No. 1 Cabot-KBI drill hole ends about 1,500 ft above the border fault and the underlying middle Proterozoic basement. High-amplitude seismic events from the Stockton formation on the southeastern flank of the large anticline may indicate undiscovered gas accumulations.

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

1994-12-31

143

Optimization of the design of DC-DC converters for improving the electromagnetic compatibility with the Front-End electronic for the super Large Hadron Collider Trackers  

E-print Network

The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DC buck converters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buck converter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.

Fuentes Rojas, Cristian Alejandro; Blanchot, G

2011-01-01

144

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

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

145

Bi-Frequency Modulated Quasi-Resonant Converters: Theory and Applications  

NASA Astrophysics Data System (ADS)

To avoid the variable frequency operation of quasi -resonant converters, many soft-switching PWM converters have been proposed, all of them require an auxiliary switch, which will increase the cost and complexity of the power supply system. In this thesis, a new kind of technique for quasi -resonant converters has been proposed, which is called the bi-frequency modulation technique. By operating the quasi-resonant converters at two switching frequencies, this technique enables quasi-resonant converters to achieve the soft-switching, at fixed switching frequencies, without an auxiliary switch. The steady-state analysis of four commonly used quasi-resonant converters, namely, ZVS buck, ZCS buck, ZVS boost, and ZCS boost converter has been presented. Using the concepts of equivalent sources, equivalent sinks, and resonant tank, the large signal models of these four quasi -resonant converters were developed. Based on these models, the steady-state control characteristics of BFM ZVS buck, BFM ZCS buck, BFM ZVS boost, and BFM ZCS boost converter have been derived. The functional block and design consideration of the bi-frequency controller were presented, and one of the implementations of the bi-frequency controller was given. A complete design example has been presented. Both computer simulations and experimental results have verified that the bi-frequency modulated quasi-resonant converters can achieve soft-switching, at fixed switching frequencies, without an auxiliary switch. One of the application of bi-frequency modulation technique is for EMI reduction. The basic principle of using BFM technique for EMI reduction was introduced. Based on the spectral analysis, the EMI performances of the PWM, variable-frequency, and bi-frequency modulated control signals was evaluated, and the BFM control signals show the lowest EMI emission. The bi-frequency modulated technique has also been applied to the power factor correction. A BFM zero -current switching boost converter has been designed for the power factor correction, and the simulation results show that the power factor has been improved.

Zhang, Yuefeng

1995-01-01

146

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

147

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

Microsoft Academic Search

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

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

1994-01-01

148

A Fully Integrated 660 MHz Low-Swing Energy-Recycling DC–DC Converter  

Microsoft Academic Search

A fully integrated 0.18 mum DC-DC buck converter using a low-swing ldquostacked driverrdquo configuration is reported in this paper. A high switching frequency of 660 MHz reduces filter components to fit on chip, but this suffers from high switching losses. These losses are reduced using: 1) low-swing drivers; 2) supply stacking; and 3) introducing a charge transfer path to deliver

Mehdi Alimadadi; Samad Sheikhaei; Guy Lemieux; Shahriar Mirabbasi; William G. Dunford; Patrick R. Palmer

2009-01-01

149

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.

150

Effect of active immunization against inhibin on hormonal concentrations and semen characteristics in Shiba bucks.  

PubMed

Active immunization against inhibin increased ovulation rate in females; in males, the effects of active immunization against inhibin on hormonal concentrations and sperm production need more investigation. To test the hypothesis that active immunization against inhibin increases FSH secretion and sperm output, the present study was undertaken to determine the effects of active immunization against inhibin on hormonal profile and sperm production in Shiba bucks. The bucks were actively immunized against inhibin alpha-subunit (immunized group, n=6) or Freund adjuvant (control group, n=5) four times, at 5-weeks intervals. Blood samples were collected twice-weekly and two successive ejaculates of semen were collected (with an artificial vagina) once-weekly. Plasma concentrations of FSH, LH and testosterone were measured by radioimmunoassay (RIA) and sperm motility characteristics were measured by computer-assisted sperm analysis (CASA). All inhibin-immunized bucks produced antibodies against inhibin. Relative to control bucks, in immunized bucks there were significant increases in plasma FSH concentrations and in sperm concentrations from 5 to 9 weeks and from 8 to 11 weeks, respectively, after primary immunization. However, plasma concentrations of LH and testosterone, semen volume, percentage of motile spermatozoa and motility parameters (straight-line velocity, curvilinear velocity and linearity index) were similar in both groups. In conclusion, active immunization against inhibin alpha-subunit increased FSH secretions and enhanced sperm production in bucks, whereas LH and testosterone concentrations, semen volume and sperm motility parameters were unaffected. Active immunization against inhibin could be used to improve fertility in Shiba bucks. PMID:16024069

Medan, M S; Watanabe, G; Nagura, Y; Fujita, M; Taya, K

2006-03-01

151

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

152

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

153

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. PMID:23987251

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

2013-01-01

154

An improved Flyback converter  

Microsoft Academic Search

This paper presents a modified Flyback converter able to operate with higher efficiency and smaller size, overcoming most of the conventional flyback converter drawbacks, and also keeping its low cost and simplicity. In particular, the proposed converter allows the mosfet off voltage to be reduced and clamped to the input, thus recovering the transformer leakage energy. As a consequence, the

G. M. Ponzo; G. Capponi; P. Scalia; V. Boscaino

2009-01-01

155

Valproate affects reproductive endocrine function, testis diameter and some semen variables in non-epileptic adolescent goat bucks.  

PubMed

Valproate (VPA) is a major antiepileptic drug with a broad spectrum of antiepileptic activity. There is, however, increasing concern about the possible effects of VPA on reproductive endocrine function. This study investigated the effects of valproate, on the endocrine and reproductive system of adolescent, non-epileptic, goat bucks. Nine goat bucks were orally treated with 62.5mg/kg valproate twice daily from 2 to 10 months of age in order to sustain therapeutic plasma concentrations of between 300 and 600 micromol/l. Seven bucks served as controls. Body weights and testicular diameters were recorded. Blood samples were collected for measurement of luteinising hormone (LH), follicle stimulating hormone (FSH) and testosterone three times weekly until sacrifice at approximately 40 weeks of age. Conventional reproductive endpoints were recorded and flow cytometric (FCM) analyses of spermatogenesis, including the sperm chromatin structure were conducted. Valproate-treated bucks had on average a higher body weight, but a lower testis diameter than controls. No significant differences were found for plasma FSH in comparison to controls. Valproate-treated bucks differed significantly from the control group by showing lower plasma concentrations of LH and testosterone and a later onset of puberty. A significantly higher proportion of sperm from valproate-treated bucks showed abnormal chromatin, demonstrating a harmful effect on DNA from valproate treatment. These results demonstrate that valproate was able to induce reproductive effects in goat bucks related to the hypothalamic-pituitary-axis, as well as to the testes. PMID:18394693

Krogenaes, A K; Taubøll, E; Stien, A; Oskam, I C; Lyche, J L; Dahl, E; Thomassen, R F; Sweeney, T; Ropstad, E

2008-07-01

156

Effects of season and feeding level on reproductive activity and semen quality in Payoya buck goats  

Microsoft Academic Search

The aim of this study was to determine if there is a seasonal pattern of reproductive activity in male Payoya goats and if this seasonality can be modulated by a higher level of nutrition. For a period of 16 months, 10 adult bucks were divided into two experimental groups that differed in their feeding level. The high nutrition group (H,

L. A. Zarazaga; J. L. Guzmán; C. Domínguez; M. C. Pérez; R. Prieto

2009-01-01

157

Dynamic characteristics analysis and instantaneous value control design for buck-type power electronic transformer (PET)  

Microsoft Academic Search

Detail dynamic characteristics analysis of buck-type PET under general load condition was accomplished and the study showed that: under general inductive load condition, the open-loop system is marginally stable and serious output voltage oscillation can be provoked by any random disturbance upon input voltage, control signal or output current. Therefore, in order to ensure the out power quality, we must

Ma Huasheng; Zhang Bo; Zheng Jianchao; Liu Xuechao

2005-01-01

158

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

NSDL National Science Digital Library

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

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

159

Modes of faulting at mid-ocean ridges W. Roger Buck1  

E-print Network

Modes of faulting at mid-ocean ridges W. Roger Buck1 , Luc L. Lavier2 * & Alexei N. B. Poliakov3 1 strain are concentrated. To study how faults form it is logical to look at mid-ocean ridges, where faults flanked by normal faults was the first feature identified as marking the axis of mid-ocean ridges when

Buck, Roger

160

A new current-source gate driver for a buck voltage regulator  

Microsoft Academic Search

A new current-source gate drive circuit is proposed for a synchronous buck voltage regulator (VR). The proposed driver can drive two MOSFETs independently with different drive currents for optimal design. Furthermore, the new drive circuit can achieve 1) significant switching loss reduction; 2) gate energy recovery; 3) reduced body diode losses and reverse recovery losses; 4) ZVS of all the

Zhiliang Zhang; Wilson Eberle; Yan-Fei Liu; P. C. Sen

2008-01-01

161

A new hybrid gate drive scheme for high frequency buck voltage regulators  

Microsoft Academic Search

This paper presents a new hybrid drive scheme for a synchronous buck voltage regulator (VR). The proposed current-source driver is used to drive the control MOSFET to achieve fast switching speed and reduce the switching loss significantly due to the parasitic inductance in addition to gate energy recovery. Conventional voltage driver is used for synchronous rectifier (SR) MOSFET for its

Zhiliang Zhang; Wilson Eberle; Ping Lin; Yan-Fei Liu; Paresh C. Sen

2008-01-01

162

Reverend Buck's Theological Dictionary and the Struggle to Define American Evangelicalism, 1802“1851  

Microsoft Academic Search

Despite a stated reliance on the plain meaning of the Bible and the dictates of common sense, antebellum evangelicals required methods to create international consensus in a trans-denominational movement. Buck's Theological Dictionary, first published in London in 1802, sought to provide a textual basis for evangelical community. By combining brief essays on orthodox belief and practice with historical entries on

Matthew Bowman; Samuel Brown

2009-01-01

163

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

E-print Network

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

Watson, Craig A.

164

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

165

Maintenance of sperm production in bucks during a third year of short photoperiodic cycles.  

PubMed

We have previously shown that reproductive seasonality of bucks was prevented for 2 consecutive years by short photoperiodic cycles. To determine the effect of the length of treatment time on bucks subjected to the same photoperiod conditions, experiments were continued for a third consecutive year on 3 groups of 6 Alpine and Saanen bucks. The control group was kept under natural photoperiodic conditions, while the experimental groups were exposed alternately to 1 month of long days and 1 month of short days (group 2M) or to 2 months of long days and 2 months of short days (group, 4M). Prolactin profiles indicated that bucks from both experimental groups responded adequately to rapid photoperiod changes as their plasma prolactin levels were significantly higher in long days (mean +/- SEM; 2M: 61.1 +/- 15.9 ng/ml; 4M: 102.2 +/- 13.5 ng/ml) than in short days (2M: 35.3 +/- 8.2 ng/ml; 4M: 46.1 +/- 9.0 ng/ml). Testosterone secretion was also dependent on day length (P < 0.0001), since testosterone concentrations of experimental animals were higher during long days (2M: 7.0 +/- 0.7 ng/ml; 4M: 10.2 +/- 1.1 ng/ml) than during short days (2M: 4.3 +/- 0.4 ng/ml; 4M: 5.0 +/- 0.9 ng/ml). Furthermore, controls displayed a high level of sexual behavior (always higher than 10%) and the proportion of bucks unable to ejaculate was significantly lower (P < 0.01) than the experimental animals (2M: 25.6%; 4M: 28.1%).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8142042

Delgadillo, J A; Leboeuf, B; Chemineau, P

1993-01-01

166

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

167

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

168

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.

169

Valproate affects reproductive endocrine function, testis diameter and some semen variables in non-epileptic adolescent goat bucks  

Microsoft Academic Search

Valproate (VPA) is a major antiepileptic drug with a broad spectrum of antiepileptic activity. There is, however, increasing concern about the possible effects of VPA on reproductive endocrine function. This study investigated the effects of valproate, on the endocrine and reproductive system of adolescent, non-epileptic, goat bucks. Nine goat bucks were orally treated with 62.5mg\\/kg valproate twice daily from 2

A. K. Krogenæs; E. Taubøll; A. Stien; I. C. Oskam; J. L. Lyche; E. Dahl; R. F. Thomassen; T. Sweeney; E. Ropstad

2008-01-01

170

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

E-print Network

EFFECT OF ZERANOL OR MELENGESTROL ACETATE (MGA) ON TESTICULAR DEVELOPMENT AND AGGRESSION IN FARMED FALLOW BUCKS A Thesis by TIMOTHY WAYNE WILSON Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 2000 Major Subject: Physiology of Reproduction EFFECT OF ZERANOL OR MELENGESTROL ACETATE (MGA) ON TESTICULAR DEVELOPMENT AND AGGRESSION IN FARMED FALLOW BUCKS A Thesis by TIMOTHY WAYNE WILSON...

Wilson, Timothy Wayne

2012-06-07

171

Improvement of Step-Down Converter Performance with Optimum Lqr and Pid Controller with Applied Genetic Algorithm  

NASA Astrophysics Data System (ADS)

The DC converter can be employed alone for the stabilization or the control of DC voltage of a battery or it can be a component of a complex converter to control the intermediate or output voltages. Due to the switching property included in their structure, DC-DC converters have a non-linear behavior and their controlling design is accompanied with complexities. But by employing the average method it is possible to approximate the system by a linear system and then linear control methods can be used. Dynamic performance of buck converters output voltage can be controlled by methods of Linear Quadratic Regulator (LQR) and PID. The former controller designing needs to positive definite matrix selection and the later is relative to desired pole places in complex coordinate. In this article, matrixes coefficients and the best constant values for PID controllers are selected based on Genetic algorithm method. The simulation results show an improvement in voltage control response.

Nejati, R.; Eshtehardiha, S.; Poudeh, M. Bayati

2008-10-01

172

Photocapacitive image converter  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

173

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

174

Single-Phase Half-Controlled Buck Rectifier Capable of Recovering Snubber Energy  

NASA Astrophysics Data System (ADS)

Single-phase half-controlled buck rectifier using a simple snubber energy recovery bridge leg is studied. When the active power devices assembled into this bridge leg are simultaneously turned on, the snubber capacitor is discharged and its stored energy is transferred to the load circuit. The experimental results confirm that the input current can be waveshaped sinusoidally with the higher efficiency than that of the conventional one.

Itoh, Ryozo; Ishizaka, Kouichi

175

Application of Resonant Snubber Switch Cell to Single-Phase Buck Rectifier  

NASA Astrophysics Data System (ADS)

Application of resonant snubber switch cell to a single-phase buck rectifier is studied. The resonant snubber switch cell consists of an only active power switching device and a LC resonant circuit. The active power switching device is then turned on and off under the soft switching conditions. The experimental results under the sinusoidal pulse-width modulation (PWM) confirm that the input current can nearly be wave-shaped sinusoidally with a near-unity power factor.

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

176

Solar integrated current-fed quasi-Z-source inverter with power buck-boost capability  

Microsoft Academic Search

Solar integrated current-fed quasi-Z-source inverter (qZSI) have been proposed to overcome the limitations of current-source inverter (CSI) and current-fed Z (impedance) source inverter (ZSI). The problems with CSI are unidirectional power flow and can perform only voltage boost operation. On the other hand ZSI is bidirectional with an additional diode and have voltage buck-boost capability. The techniques of ZSI and

S. Karolin Selvia; F. X. Edwin Deepak

2012-01-01

177

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

178

Enhanced Buck–Boost Neutral-Point-Clamped Inverters With Simple Capacitive-Voltage Balancing  

Microsoft Academic Search

In traditional neutral-point-clamped (NPC) inverters, two major operating issues encountered are their relatively limited voltage-buck variation range and capacitive-voltage imbalance, which can cause low-order harmonics to appear at the inverter output. Various methodologies have so far been introduced for extending the inverters' variation range to include voltage-boost operation, but they generally require the inclusion of large passive components or have

Kuan Khoon Tan; Feng Gao; Poh Chiang Loh; Frede Blaabjerg

2010-01-01

179

A High Efficiency Synchronous Buck VRM with Current Source Gate Driver  

Microsoft Academic Search

In this paper, a new current source gate drive circuit is proposed for high efficiency synchronous buck VRMs. The proposed circuit achieves quick turn-on and turn-off transition times to reduce switching loss and conduction loss in power MOSFETS. The driver circuit consists of two sets of four control switches and two very small inductors (typically 50 nH-300 nH each at

Wilson Eberle; Zhiliang Zhang; Yan-Fei Liu; P. C. Sen

2007-01-01

180

Putting Buck v. Bell in Scientific and Historical Context: A Response to Victoria Nourse  

Microsoft Academic Search

In this article written for a law-review symposium in response to a presentation on the infamous 1927 U.S. Supreme Court opinion in Buck v. Bell, Edward J. Larson argues that, at the time that the case was decided, eugenics was on the incline, not the decline. In the 1920s, the American scientific and medical community broadly backed eugenic remedies for

Edward J. Larson

2012-01-01

181

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. PMID:24790768

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

2014-01-01

182

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

183

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

184

Gallium phosphide energy converters  

Microsoft Academic Search

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

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

1995-01-01

185

Wildlife Management: The Case of Bucks Only Hunting The model in Figure 1 is adapted from an example in Ken Watt's (1968) text on Ecology and  

E-print Network

an example in Ken Watt's (1968) text on Ecology and Resource Management. It distinguishes between bucks that this population will grow, despite the aggressive hunting of the adult bucks. This diagram is adapted from Watt's description of a theoretical deer herd (Watt 1968, p. 127). He uses the numerical example to argue against

Ford, Andrew

186

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

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

1990-01-01

187

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

188

Thermionic energy converter investigations  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

189

Modular voltage source converter  

US Patent & Trademark Office Database

Voltage source converter based on a chain-link cell topology including one or more phases, each of the phases having one or more series-connected chain-link cell modules connected to each other. The output voltage of the voltage source converter is controlled by control signals applied to the series-connected chain-link cell modules. In case of failure of a chain-link cell module, that module is controlled, by the control signals, such that zero output voltage is provided at its output voltage AC terminal.

2013-08-06

190

Semen characteristics and plasma levels of testosterone after bilateral vasectomy in bucks.  

PubMed

The effects of bilateral vasectomy on the seminal characteristics were assessed in six bucks of the Canarian breed. In addition, we tried to establish the effects of vasectomy on the plasmatic concentrations of testosterone and the libido of the bucks. Semen samples were collected once a week from 8 weeks before to 16 weeks after vasectomy; blood samples were collected prior to vasectomy, and then at once and 1 week after vasectomy and every 2 weeks from the week 4 to the end of the experiment. One week after the vasectomy, ejaculated spermatozoa were non-motile and the percentage of live spermatozoa was below 5% in all vasectomized males; in addition, the total number of cells/ejaculate was 3100 x 106 and 30 x 106 spermatozoa in the control and vasectomized males, respectively. Our results suggest that the vasectomized males may be used as oestrus detectors, without risks of accidental fecundating, only 1 week after vasectomy. Before vasectomy, no significant differences were observed in plasma levels of testosterone between the vasectomized and control males (5.4 +/- 1.2 and 3.9 +/- 1.4 ng/ml, respectively); from 4 to 12 weeks after vasectomy, a marked decrease in the testosterone concentration in all males (vasectomized and control bucks) was observed. From 12 weeks after vasectomy until the end of the experiment, four of the vasectomized males and the control males recovered their normal libido. The results suggest that vasectomy did not exert a remarkable effect on the steroidogenic functionality of the testicle. PMID:12464078

Batista, M; Prats, N; Calero, P; González, F; Cabrera, F; Medrano, A; Gracia, A

2002-12-01

191

Effects of season and feeding level on reproductive activity and semen quality in Payoya buck goats.  

PubMed

The aim of this study was to determine if there is a seasonal pattern of reproductive activity in male Payoya goats and if this seasonality can be modulated by a higher level of nutrition. For a period of 16 months, 10 adult bucks were divided into two experimental groups that differed in their feeding level. The high nutrition group (H, n=5) received 1.6 times their maintenance food requirements. The control nutrition group (C, n=5) received a diet that supported 1.1 times their maintenance requirements. Body weight and testosterone concentrations were determined weekly, and testicular weight was determined every 2 weeks. Sexual behaviour and semen characteristics were determined monthly. Feeding level did not affect the onset or the end of the reproductive activity as measured by testosterone concentrations, with high testosterone concentrations between July and November. Ejaculation latency was positively influenced by feeding level: 43.2+/-2.2s vs. 61.6+/-3.2s for H and C group, respectively (P<0.001). The percentage of males that ejaculated or that were sexually active was higher in the H group (P<0.01). No differences between feeding levels were observed in the different semen characteristics studied. However, major differences between months were observed for all studied variables. These results lead us to conclude that Payoya bucks exhibit large seasonal variation in their reproductive activity. Higher feeding level allowed a better sexual behaviour in bucks in late spring, when male effect is used on the local livestock to breed females. PMID:19249088

Zarazaga, L A; Guzmán, J L; Domínguez, C; Pérez, M C; Prieto, R

2009-05-01

192

Single layer centrifugation (SLC) improves sperm quality of cryopreserved Blanca-Celtibérica buck semen.  

PubMed

The aim of the present study was to evaluate the effect of sperm selection by means of single layer centrifugation (SLC) on sperm quality after cryopreservation, either when SLC is used before freezing or after thawing, using Blanca-Celtibérica buck semen collected by electroejaculation (EE). Ejaculates from six bucks were collected by EE and divided into two aliquots. One of them (unselected) was diluted with Biladyl(®) by the two-step method and frozen over nitrogen vapor. The other aliquot was selected by the SLC technique and subsequently frozen in the same way as the unselected samples (SLC before freezing). In a further treatment, two unselected straws were thawed and SLC was carried out (SLC after thawing). At thawing, sperm motility of all samples ((i) unselected; (ii) selected before freezing and (iii) selected after thawing) was evaluated by CASA. In addition, integrity of the plasma membrane, mitochondrial membrane potential, ROS production and DNA fragmentation index were assessed by flow cytometry. Most of the sperm parameters were improved (P?0.001) in samples selected by SLC after thawing in relation to unselected or selected by SLC before freezing. The percentage of progressive motile spermatozoa was greater (86%) for sperm samples selected after thawing compared with unselected (58%) or selected before freezing (54%). Moreover, percentages of spermatozoa with intact plasma membrane and spermatozoa with high mitochondrial membrane potential (hMMP) were also greater for sperm samples selected after thawing compared to sperm samples unselected or selected before freezing (spermatozoa with intact plasma membrane: 80% vs. 32% vs. 12%; spermatozoa with hMMP: 54% vs. 1% vs. 15%; respectively). Therefore, sperm quality after cryopreservation is improved in Blanca-Celtibérica buck ejaculates collected by EE when a sperm selection technique such as SLC is carried out after thawing. PMID:23084569

Jiménez-Rabadán, P; Morrell, J M; Johannisson, A; Ramón, M; García-Álvarez, O; Maroto-Morales, A; Alvaro-García, P J; Pérez-Guzmán, M D; Fernández-Santos, M R; Garde, J J; Soler, A J

2012-12-01

193

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

194

Catalytic Converters and Nanocatalysts  

NSDL National Science Digital Library

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

2014-09-08

195

Muslim Converts in Prison  

Microsoft Academic Search

Abstract: There has been something of a moral panic about individuals converting to Islam whilst incarcerated. A number of newspaper articles have suggested that within prisons there is a potentially toxic mix of extremist ideology and a criminal past. This article presents the results of a study exploring conversion to Islam within two prisons in England. The main findings suggest

BASIA SPALEK; SALAH EL-HASSAN

2007-01-01

196

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

1989-01-01

197

Interpretation of the Perey-Buck nonlocality in terms of the relativistic optical model formalism  

SciTech Connect

Under certain conditions the solution of a nonlocal, nonrelativistic Schroedinger equation is the same as the upper component of a relativistic four-spinor which obeys a local Dirac equation. This result is obtained by combining the observation recently made by Fiedeldey and Sofianos, that a nonlocal Schroedinger equation can be transformed into a local one if a gradient term (or velocity term) is added, together with the well-known fact that the upper component of the solution of a Dirac equation also obeys a second-order equation which has a gradient term. For the case of a nonlocality of the Perey-Buck--type, the gradient term is nearly equal to the Darwin term, and hence the conditions for the validity of the relativistic-nonrelativistic equivalence are nearly valid. A numerical example is presented for the case of 21.7 MeV neutrons scattering elastically from /sup 40/Ca, for which a local relativistic optical potential has been recently obtained. The gradient term is given in terms of derivatives of the Wronskian of two independent solutions of the nonlocal equation, and numerical values for the latter are compared with the corresponding relativistic quantity. The differences are not larger than 25%. Results for the nonlocality due to exchange are also shown, and are found to be very similar to the Perey-Buck nonlocality. An implication of these results is that the relativistic optical potential may be less nonlocal than the nonrelativistic one.

Rawitscher, G.H.

1985-04-01

198

Thermionic energy converters  

NASA Technical Reports Server (NTRS)

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

Morris, J. F. (inventor)

1983-01-01

199

Power electronic converter technology  

Microsoft Academic Search

The present state of the art in DC-DC, AC-DC, DC-AC, and AC-AC converter technology is presented along with their typical areas of applications. Advances made in the last decade that are finding use in industrial, commercial, and military applications are emphasized. Soft switching, in which power device switching stresses are reduced due to circuit resonances, has dominated DC-DC power conversion

ROBERT L. STEIGERWALD

2001-01-01

200

Free FLV Converter  

NSDL National Science Digital Library

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

2007-01-01

201

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

202

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

203

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

204

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

1995-09-01

205

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

Microsoft Academic Search

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

Susan W. Margulis

1993-01-01

206

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

ERIC Educational Resources Information Center

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

Mahon, Jack

207

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

Microsoft Academic Search

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

Bin Shao; Bill Liu

2010-01-01

208

A Speed Control Of Pmbldcm Drive Using Single Stage Pfc Half Bridge Converter  

E-print Network

In this paper, a buck half-bridge DC-DC converter is used as a single-stage power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of this PFC converter is a diode bridge rectifier (DBR) fed from single-phase AC mains. The PMBLDCM is used to drive a compressor load of an air conditioner through a threephase VSI fed from a controlled DC link voltage. The speed of the compressor is controlled to achieve energy conservation using a concept of the voltage control at DC link proportional to the desired speed of the PMBLDCM. Therefore the VSI is operated only as an electronic commutator of the PMBLDCM. The stator current of the PMBLDCM during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed PMBLDCM drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Matlab-Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm PMBLDC motor. The evaluation results of the proposed speed control scheme are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.

Dr. M. Sridhar; Sayed Baji Shaik

209

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. PMID:24135390

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

2013-01-01

210

Low pressure solar thermal converter  

Microsoft Academic Search

The current development of solar power converters with air as working fluid focuses mostly on concentrating collectors combined with hot-air engines, and on very low temperature solar tower concepts. Whilst concentrating collectors and Stirling engines need complex technology, solar tower converters have very low efficiencies and require large installations. Pressurized containers as energy converters offer the advantage of simplicity, but

Gerald Muller

211

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

212

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

213

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

214

Gallium phosphide energy converters  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

215

Gallium phosphide energy converters  

SciTech Connect

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

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

1995-10-01

216

Gallium phosphide energy converters  

NASA Astrophysics Data System (ADS)

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

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

1995-10-01

217

Effect of naloxone on the plasma levels of LH, FSH, prolactin and testosterone in Beetal bucks.  

PubMed

Ten adult male Beetal goats were used for the study to elucidate the modulation of gonadotrophin, prolactin and testosterone secretion by endogenous opioid peptides. An indwelling catheter was placed in the jugular vein of each buck 20h before the onset of the experiment. Bucks were divided randomly into two groups: Group I (n=5) received naloxone at a dose rate of 1mg/kg body weight (BW) and Group II (n=5) received naloxone at a dose rate of 2mg/kg BW intravenous. Blood samplings were done from 2h before treatment until 2h after treatment at 15min intervals. Blood samples were quantified for plasma LH, FSH and prolactin concentration using a heterologous double antibody radioimmunoassay (RIA) and testosterone concentration was quantified by coat-a-count RIA kit. The mean plasma LH levels during pretreatment phase were 0.41+/-0.03ng/ml in Group I and 0.44+/-0.02ng/ml in Group II which significantly (p<0.05) increased to 0.91+/-0.05ng/ml in Group I and 1.53+/-0.07ng/ml in Group II. The mean plasma FSH levels did not show a difference in pre- and post-treatment animals in both groups. A significant (p<0.05) increase in plasma testosterone concentration was observed in both groups after naloxone treatment, whereas, a decrease (p<0.05) was observed in plasma prolactin levels after naloxone treatment. Thus, it can be concluded that endogenous opioids do play an important role in modulating plasma LH, prolactin and testosterone concentrations in male goats. PMID:10818303

Singh; Dixit; Singh; Georgie; Dixit

2000-07-01

218

Resistive anode image converter  

NASA Technical Reports Server (NTRS)

The invention of an apparatus for imaging soft X-ray and ultraviolet electromagnetic radiation and charged particles was described. The apparatus includes a pair of microchannel electron multiplier plates connected in a cascaded chevron configuration which intercepts an incident beam of radiation or charged particles. Incident photons or charged particles strike the front surface of the chevron configuration causing emission of electrons. The electrons are accelerated by a voltage gradient and strike the inner side walls of the individual channels, causing emission of secondary electrons. Accelerated and multiplied secondary electrons impinge upon a resistive anode after they transverse the chevron configuration. A pulse position circuit converts the magnitude or transit time of the currents flowing from the point of impact of the electrons on the resistive anode to four contact electrodes mounted on their periphery of the resistive anode into the spatial coordinates of electron impact.

Lampton, M. L.; Paresce, F. (inventors)

1976-01-01

219

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

220

Testicular biochemicals, sperm reserves and daily sperm production of West African dwarf bucks fed varied levels of dietary aflatoxin.  

PubMed

An experiment was conducted with twenty West African dwarf (WAD) bucks (5-6 months old) to assess reproductive potentials of growing WAD bucks to varied dietary aflatoxin of 0 ?g/kg, 50 ?g/kg, 100 ?g/kg and 150 ?g/kg containing in diets 1 (control) 2, 3 and 4 respectively, for a period of 12 weeks. At the end of the 12th week, the reproductive tracts of bucks were excised and homogenised in physiological saline for assessment of glucose, total protein and testosterone concentration, gonadal and extra gonadal sperm reserves. Results showed that gonadal and extra-gonadal sperm reserves of goats fed control diet (2.71×10(9) and 3.07×10(9) spermatozoa respectively) were superior (p<0.05) to those fed 50 ?g/kg, 100 ?g/kg and 15 0?g/kg [(1.59×10(9) and 2.33×10(9)), (1.09×10(9) and 2.45×10(9)) and (1.00×10(9) and 1.41×10(9)) spermatozoa respectively]. Daily sperm production of bucks fed the control diet was significantly (p<0.05) higher (7.60×10(8) spermatozoa/testis) than those fed 50 ?g/kg (4.47×10(8)), 100 ?g/kg (3.07×10(8)) and 150 ?g/kg (2.80×10(8) spermatozoa/testis). Sperm production efficiency also follows the same trend as daily sperm production. Glucose and total protein concentration in the testes declined significantly as the aflatoxin level increases in the diets. Testosterone level was significantly lower in goats fed 100 ?g/kg than others. The study suggest that exposure of male goats to dietary aflatoxin up to 50 ?g/kg diet will reduced testicular biochemical and testosterone with resultant depression in sperm storage capability and daily sperm production in the animals. PMID:24929896

Ewuola, E O; Jimoh, O A; Bello, A D; Bolarinwa, A O

2014-08-01

221

Spontaneous uptake of exogenous DNA by goat spermatozoa and selection of donor bucks for sperm-mediated gene transfer.  

PubMed

Sperm-mediated gene transfer (SMGT) has been long heralded as a faster and cheaper alternative to more commonly used methods of producing transgenic animals. In this study, the capra semen ejaculates were pooled together and then incubated in vitro with DIG-labeled DNA. The binding and internalizing rates were observed by the in situ hybridization methods. We also compared the standard sperm parameters and the efficiencies of interaction with exogenous DNA of 60 individuals to select donor bucks for SMGT. It was showed that labeled exogenous DNA was detected in different localizations in spermatozoa but genuine DNA uptake, in contrast to mere binding, seems to be limited to the postacrosomal region. The removal of seminal plasma increased significantly (P < 0.01) the capability in picking up exogenous DNA. Use of frozen-thawed semen (without cryoprotectant agents) and Triton X-100 treatment also increased significantly (P < 0.01) the DNA-binding capacity, but reduced the sperm viability. The binding rates (the proportion of labeled-DNA positive spermatozoa to all the spermatozoa counted) of 60 buck individuals were in the range of 3.08-73.39%, and the internalizing rates (the proportion of DNaseI-treated labeled-DNA positive spermatozoa to all the spermatozoa counted) were 4.83-70.00%. About 8.34% (5/60) bucks showed high binding, but low internalizing ability. Chi-square test showed that there was significant difference among the breeds (x(2) = 26.515, P < 0.01). Eight individual bucks that demonstrated high DNA uptake were selected for SMGT. It was demonstrated that the goat spermatozoa was capable of spontaneous uptake of exogenous DNA. Seminal fluid inhibits DNA uptake and that membrane disruption increases DNA binding but greatly diminishes uptake. PMID:21667250

Zhao, Yongju; Yu, Mingju; Wang, Lingbin; Li, Yaofeng; Fan, Jingsheng; Yang, Qian; Jin, Yaping

2012-03-01

222

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

223

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.

224

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

225

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

226

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

227

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

228

Converting Technology into a Company  

E-print Network

;2 Science-Driven Disruptive Technology Development and Marketplace Realization Science BreakthroughPlasmasol: Converting Technology into a Company Christos Chrisodoulatos, Ph.D. Vice Provost #12 Technology Chemistry/ Materials Sensors EnviroSense? Engineering Technology Chemistry/ Materials Met

Yang, Eui-Hyeok

229

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

230

A Binary Coded Decimal Converter  

Microsoft Academic Search

Of the many different coding schemes possible, the 8-4-2-1 binary decimal code was felt to be the most useful for data handling systems. A transducer wes developed for converting shaft positions to digital numbers in this code. The converter is small, light weight, and produces 10,000 binary coded decimal numbers in 100 revolutions of the input shaft. No ambiguity of

Martin Ziserman

1956-01-01

231

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

E-print Network

problem and simplify the control timing of the auxiliary switch. The main and auxiliary switches the turn-off losses due to the current tailing of the IGBTs. However, the turn-on of the main switch Engineering, University of Colorado, Boulder, CO 80309 USA (e-mail: maksimov@colorado.edu). Color versions

232

Design, Construction and Performance of a Buck-Boost Converter for an Ultracapacitor-Based Auxiliary Energy System for Electric Vehicles  

E-print Network

-based or hydrogen-based energy storage systems, unlike batteries, are unable to accept energy from regenerative braking. For this reason, hybrid systems use an auxiliary energy system that is able to receive, medium-low energy content (enough for enduring short acceleration periods and accepting regenerative

Catholic University of Chile (Universidad Católica de Chile)

233

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

SciTech Connect

Three new dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. Of the three circuits the single-phase and three-phase versions of the dual-active-bridge topology demonstrate minimal electrical stresses, better utilization of the transformer, bi-directional and buck-boost model of operation. The power-transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. The measured leakage inductance at 50 kHz is seen to be in the vicinity of 150-250 nH, with power density of approximately 0.1 kg/kW. Based on the single-phase dual-active-bridge topology, a 50kW, 50-kHz converter operating at an input voltage of 200V dc and an output voltage of 1,600V dc was fabricated.

Kheraluwala, M.H.

1991-01-01

234

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

NASA Astrophysics Data System (ADS)

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

Singh, Bhim; Bist, Vashist

2014-01-01

235

The "female effect" in Australian cashmere goats: effect of season and quality of diet on the LH and testosterone response of bucks to oestrous does.  

PubMed

The effects of season, diet and exposure to oestrous females on LH and testosterone secretion were examined in mature cashmere bucks to determine whether there is a seasonal cycle of LH and testosterone secretion, and whether this can be modulated by long-term differential nutrition and exposure to oestrous females. Three-year-old bucks were individually housed under natural photoperiod at 29 degrees S 153 degrees E and fed diets of high (crude protein 17.6%, metabolizable energy 8.3 MJ kg-1) or low (crude protein 6.9%, metabolizable energy 6.6% MJ kg-1) quality for 16 months ad libitum (n = 6 per treatment). Blood samples were collected to determine pulsatile LH and testosterone secretion immediately before experimental feeding, one month later, and every second month thereafter. Samples were collected for an 8 h period on successive days with the bucks isolated on the first day and each exposed to a single oestrous doe for the duration of the second day. In the absence of oestrous females, bucks exhibited a circannual pattern of secretion for both hormones with pulse frequency and mean concentrations highest in late summer and autumn and lowest in late winter and spring. Testosterone pulse amplitude followed a similar pattern, but LH pulse amplitude was highest in spring and lowest in autumn, indicating a seasonal shift in the relationship between the two hormones. Exposure to oestrous does increased LH and testosterone secretion depending on both season and diet. Responses were evident during summer, autumn and early winter, with bucks on a high quality diet exhibiting an earlier and more prolonged period of responsiveness than did bucks on a low quality diet, peaking in February compared with June. The magnitude of the LH and testosterone response was also significantly greater in bucks on a high quality diet. Weight loss during autumn appeared to reduce responsiveness in both treatments. These results demonstrate that there is a seasonal cycle in LH and testosterone secretion in mature cashmere bucks, and that nutrition and oestrous females are powerful modulators of the secretion of these hormones in a seasonally dependent way. PMID:8021873

Walkden-Brown, S W; Restall, B J; Norton, B W; Scaramuzzi, R J

1994-03-01

236

New converter circuitry for PV applications using multilevel converters  

Microsoft Academic Search

This paper presents an analysis and the design of an off grid PV system for providing electricity for remote area. The system composed of dc-dc multilevel boost converter (MLBC) which is used for extracting maximum power from the cell. It has been chosen to generate three dc voltages at its output terminal. In addition to, a multilevel dc link inverter

Mostafa Mousa; Mahrous E. Ahmed; M. Orabi

2009-01-01

237

High efficiency thermionic converter studies  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

238

Convertible Gas-Turbine Engines  

NASA Technical Reports Server (NTRS)

Convertible engine aircraft gas-turbine is two engines in one. Produces turbofan thrust, turboshaft power, or any combined thrust and shaftpower continously while operating up to full speed. Used to power vertical/short-takeoff-and-landing (V/STOL) airplanes and advanced high-speed rotorcraft. Rotorcraft shows use of convertible engines rather than separate engines for rotor power and forward thrust affords advantages in installation and save 16 percent in fuel and 20 percent in direct operating costs. Engine used for propulsion of new high-speed rotorcraft that needs both thrust and shaft power. Also used to cross-couple fans of two-engine V/STOL aircraft.

Abdalla, K. L.; Mcardle, J. G.; Lindsay, H.

1988-01-01

239

Stirling Converters For Solar Power  

NASA Technical Reports Server (NTRS)

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

Shaltens, Richard K.; Schreiber, Jeffrey G.

1993-01-01

240

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

241

Multilevel converters for power system applications  

SciTech Connect

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

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

1995-09-01

242

New ?-? voltage to frequency converter  

Microsoft Academic Search

The voltage to frequency converter (VFC) is an oscillator whose frequency is linearly proportional to the control voltage. There are two common VFC architectures: the current steering multivibrator and the charge-balance VFC. For higher linearity, the charge-balancing method is preferred. The charge balanced VFC may be made in asynchronous or synchronous (clocked) forms. The synchronous charge balanced VFC or \\

Milan Stork

2002-01-01

243

Parametric study of laser photovoltaic energy converters  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

244

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

245

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

Microsoft Academic Search

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

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

2007-01-01

246

Effects of N-methyl-D,L-aspartate on LH, GH, and testosterone secretion in goat bucks maintained under long or short photoperiods.  

PubMed

Photoperiod modulates reproduction in goats. We tested the hypothesis that the excitatory glutamatergic tone is reduced in the photoinhibited goat. The objectives of this study were to determine the effect of photoperiod and glutamatergic stimulation on LH, GH, and testosterone (T) secretion in goat bucks. Eight mature, intact bucks were used in two simultaneous 4 x 4 Latin square designs. Variables were two photoperiod regimens (short day; SD, 10 h light:14 h dark, n = 4; vs long day; LD, 16 h light:8 h dark, n = 4) and four doses of N-methyl-D-L-aspartate (NMA; 0, 1, 2 and 4 mg/kg BW, i.v.). Venous blood was obtained for 2 h before and after NMA injection, followed by GnRH injection and then a final 1 h of sampling. Injection of NMA increased (P < 0.002) LH secretion within 20 min. This increase was sustained for 120 min, but the response was most pronounced in LD goats. The increase in mean LH was associated with a concomitant dose-dependent increase in pulse frequency (P < 0.006). However, NMA treatment had no effect (P > 0.10) on LH pulse amplitude. The release of LH after injection of GnRH was not affected by photoperiod. Exposure of bucks to LD reduced T secretion relative to that of SD bucks (P < 0.01). However, GH secretion was enhanced in LD bucks (P< 0.001). The response of GH to NMA was dependent on photoperiod history. A highly significant immediate and sustained increase (P < 0.001) was observed in LD but not in SD bucks within 10 min. Overall, a dose-dependent increase (P < 0.01) in T secretion was stimulated by NMA in both LD and SD bucks. These results indicate that NMA receptors may be involved in the regulation of LH, GH, and testosterone secretion in the goat. Furthermore, length of day influences GH secretion in the goat and NMA receptor activation had divergent effects on the secretion of this hormone. PMID:12078744

Gazal, S; Kouakou, B; Amoah, E A; Barb, C R; Barrett, J B; Gelaye, S

2002-06-01

247

Sexually active bucks are able to stimulate three successive groups of females per day with a 4-hour period of contact.  

PubMed

Bucks rendered sexually active by a photoperiod treatment of long days can induce fertile ovulation in a group of goats with only 4 h of contact daily with a male:female ratio of 1:10. Here we tested whether such bucks could induce fertile ovulations when stimulating successively three different groups of anovulatory goats when interacting 4 h per day during 15 consecutive days. Control males (n=3) were introduced in the control group (n=25) of does at 8:00 h and were removed at 12:00 h. Experimental males (n=3) were in contact with the experimental groups of does: from 8:00 h to 12:00 h with a first group (n=27), from 12:00 h to 16:00 h with a second group (n=26) and with a third one (n=27) from 16:00 h to 20:00 h. Bucks were then placed until next day in another pen. Both in the control and the experimental groups, more than 85% of females ovulated, and the proportions did not differ between the control and experimental groups (P?0.67) or between the three experimental groups (P?0.67). Moreover, the ovulation rate did not differ significantly between the control and the experimental females nor between the three experimental groups. Bucks were able to fertilize more than 72% of does independently of the number of females they were exposed to (P?0.17). Finally, more than 58% of females kidded and fertility did not differ between the control and experimental groups (P=1) nor among experimental groups (P?0.77). We conclude that sexually active bucks are able to induce fertile ovulation in three successive groups of anovulatory goats even when the period of contact between sexes is reduced to 4 h per day. PMID:22366159

Bedos, M; Velázquez, H; Fitz-Rodríguez, G; Flores, J A; Hernández, H; Duarte, G; Vielma, J; Fernández, I G; Retana-Márquez, M S; Muñoz-Gutiérrez, M; Keller, M; Delgadillo, J A

2012-05-15

248

A 400 W flyback converter  

Microsoft Academic Search

It is demonstrated that it is possible to manufacture a very compact high-power switch-mode power supply based on the flyback technique using standard components, with no sacrifice in performance and operation at 80 kHz. A superior flyback converter can be designed on the basis of the following criteria: (1) choosing a pulse ratio to optimize the switching transistor\\/diode; (2) assuring

B. Assow

1989-01-01

249

Human Lung Angiotensin Converting Enzyme  

PubMed Central

To enable its immunohistologic localization, angiotensin converting enzyme (EC 3.4.15.1) from human lung was solubilized by trypsinization and purified ?2,660-fold to apparent homogeneity from a washed lung particulate fraction. The specific activity of pure enzyme was estimated to be 117 ?mol/min per mg protein with the substrate hippuryl-l-histidyl-l-leucine. Consistent with previously described lung enzyme studies, catalytic activity was strongly inhibited by EDTA, O-phenanthroline, SQ 20,881, and SQ 14,225 and increased by CoCl2. SQ 20,881 was a somewhat more potent inhibitor than SQ 14,225, unlike rabbit lung enzyme. The Michaelis constant (Km) with hippuryl-l-histidyl-l-leucine was 1.6 mM. The molecular weight was estimated at 150,000 from sucrose density gradient centrifugation. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed a single polypeptide chain estimated at 130,000 daltons. Rabbit antibody to human lung enzyme was prepared by parenteral administration of pure angiotensin-converting enzyme in Freund's adjuvant. Rabbit antibody to human lung angiotensin-converting enzyme appeared to crossreact weakly with the rabbit enzyme and strongly inhibited the catalytic activity of the enzymes from human serum, lung, and lymph node. The specificity of the rabbit antibody and purity of the final human lung enzyme preparation was suggested by the single precipitin lines obtained by radial double immunodiffusion, and by the coincidence of enzyme catalytic activity and immunoreactivity on polyacrylamide gel electrophoresis, with both relatively pure and highly impure enzymes. Generally applicable sensitive analysis of acrylamide gels for immunoreactivity (and subsequently for any other activity) by use of intact gel slices in radial double immunodiffusion was devised. Human lung enzyme was very tightly bound to and catalytically active on anti-human enzyme antibody covalently bound to Sepharose 4B, and could not be readily dissociated without inactivation. Antibody to human lung angiotensin converting enzyme has permitted tissue localization of the enzyme, which appears to be clinically useful in diseases associated with abnormal abundance of angiotensin-converting enzyme in tissues, such as sarcoidosis. Images PMID:6259212

Friedland, Joan; Silverstein, Emanuel; Drooker, Martin; Setton, Charlotte

1981-01-01

250

RESEARCH ARTICLE OPEN ACCESS An ANN Based Speed Control of PMBLDCM Drive Using a Single-Stage PFC Half-Bridge Converter  

E-print Network

In this paper, a buck half-bridge DC-DC converter is used as a single-stage power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of this PFC converter is a diode bridge rectifier (DBR) fed from single-phase AC mains. The PMBLDCM is used to drive a compressor load of an air conditioner through a three-phase VSI fed from a controlled DC link voltage. The speed of the compressor is controlled to achieve energy conservation using Back Propagation network Algorithm Where DC link voltage is controlled proportional to the desired speed of the PMBLDCM. Therefore the VSI is operated only as an electronic commutator of the PMBLDCM. The stator current of the PMBLDCM during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed PMBLDCM drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Matlab-Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm PMBLDC motor. The evaluation results of the proposed speed control scheme with Back propagation agorithm a concept of ANN (Artificial neural network)are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.

C. B. Saravanan; G. Devanatha Reddy

251

Cell modulated DC/DC converter  

E-print Network

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

Warren, James Raymond, III

2005-01-01

252

Expression, purification and structural analysis of recombinant rBdh-2His?, a spermadhesin from buck (Capra hircus) seminal plasma.  

PubMed

Spermadhesins, a family of secretory proteins from the male genital tract of ungulate species, belong to the group of animal lectins. Spermadhesins have a prominent role in different aspects of fertilisation, such as spermatozoid capacitation, acrosomal stabilisation, sperm-oviduct interaction and during sperm-oocyte fusion. Proteins (spermadhesins) in buck seminal plasma were described. In the present study, bodhesin Bdh-2 cDNA present in buck seminal plasma was subcloned with the expression plasmid pTrcHis TOPO used to transform Escherichia coli Top10 One shot cells. The recombinant clones were selected by growth in 50 µg mL?¹ ampicillin-containing LB broth and polymerase chain reaction amplification. Recombinant rBdh-2His? synthesis was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and followed by immunoblotting using monoclonal anti-His antibody. Production of rBdh-2 using low temperatures was not satisfactory. Greater production of rBdh-2 occurred with 1.5mM isopropyl ?d-thiogalactoside after 2h of induction. The method used to purify rBdh-2 was affinity chromatography on a His-Trap column following ion-exchange chromatography on a DEAE-Sephacel column. The secondary structure of the rBdh-2His? was evaluated by spectral profile circular dichroism (CD). The prevalence of secondary structures like ?-sheets, with fewer unfolded structures and ?-helices, was confirmed. The structure of rBdh-2His? remained stable up to 35°C. However, significant structural changes were observed at temperatures higher than 40 °C related to a distortion of the CD spectrum. PMID:22541546

Nascimento, Antônia Sâmia F; Cajazeiras, João B; Nascimento, Kyria S; Nogueira, Sara Monalisa S; Sousa, Bruno L; Teixeira, Edson H; Melo, Luciana M; da Cunha, Rodrigo Maranguape S; Silva, André Luiz C; Cavada, Benildo S

2012-01-01

253

Auxiliary resonant DC tank converter  

DOEpatents

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

Peng, Fang Z. (Knoxville, TN)

2000-01-01

254

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

255

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

256

Nonlinear-optic IR radiation converters  

NASA Astrophysics Data System (ADS)

A new class of instruments, nonlinear-optic (parametric) IR-visible converters, is described. A geometrical optics approximation and the diffraction theory are presented, and an analysis is made of the converter efficiency, noise characteristics, and threshold sensitivity of IR nonlinear-optic IR detection schemes. The theoretically derived converter parameters are compared with experimental data.

Gainer, Aleksandr V.

257

Photovoltaic converters for solar-pumped lasers  

NASA Technical Reports Server (NTRS)

The authors describe a mathematical parametric study of converters used to convert laser radiation to electricity for space-based laser power systems. Two different lasers, the 1.06-micron Nd laser and the 1.315-micron iodine laser, are used in the vertical junction converter. The calculated efficiency is 50 percent for a 100-junction Si photovoltaic converter when used with a Nd laser. The calculated efficiency for a 1000-junction Ga(0.53)In(0.47)As photovoltaic converter is 43 percent when used with an iodine laser.

Walker, Gilbert H.; Heinbockel, John H.

1988-01-01

258

Radicalization of Homegrown Sunni Militants in the United States: Comparing Converts and Non-Converts  

Microsoft Academic Search

Are the mechanisms and processes that lead to radicalization different for Muslim converts and non-converts in the United States? While many scholars attempt to explain why people violently radicalize, the theories are diverse and most treat converts and non-converts the same. This study answers this question by categorizing the many radicalization theories into three levels of analysis so that cases

Scott Matthew Kleinmann

2012-01-01

259

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

Microsoft Academic Search

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

Mengmeng Du; Hoi Lee

2010-01-01

260

SciHadoop: Array-based Query Processing in Hadoop Joe B. Buck Noah Watkins Jeff LeFevre Kleoni Ioannidou  

E-print Network

is performed on a single node, and data is read serially from the file system. The SWAMP project [18] has beenSciHadoop: Array-based Query Processing in Hadoop Joe B. Buck Noah Watkins Jeff LeFevre Kleoni,jayhawk,jlefevre,kleoni,carlosm,alkis,scott}@cs.ucsc.edu ABSTRACT Hadoop has become the de facto platform for large-scale data analysis in commercial applications

Polyzotis, Neoklis (Alkis)

261

A single-stage fuel cell energy system based on a buck-boost inverter with a back-up unit  

Microsoft Academic Search

When low-voltage unregulated fuel cell (FC) output is conditioned to generate AC power, two stages are usually required: a boost stage and an inversion one. In this paper, the buck-boost inverter topology that achieves both boosting and inversion functions in a single-stage is used as a building block to develop a single-phase FC-based energy system which offers high conversion efficiency,

M. Jang; M. Ciobotaru; V. G. Agelidis

2011-01-01

262

A Single-Stage Fuel Cell Energy System Based on a Buck--Boost Inverter with a Backup Energy Storage Unit  

Microsoft Academic Search

An energy system powered by a low-voltage fuel cell (FC) is conditioned to generate higher--voltage regulated ac voltage. The power conditioning system typically requires two power stages: a boost stage and an inversion stage. In this paper, the buck--boost inverter topology that achieves both boosting and inversion functions in a single stage is used as a building block to develop

Minsoo Jang; Mihai Ciobotaru; Vassilios G. Agelidis

2012-01-01

263

Microcomputer control of power converters  

SciTech Connect

Thyristor power converters are charac terized by an inherent discrete control action and are, therefore, particularly well suited to on - line control by microcomputers. The paper presents a new design of digital controllers based upon powerful 16-bit or bit -slice microprocessors, which provide high firing time resolution and enough computing power to implement sophis ticated control strategies. Both hardware and software are discussed, with special emphasis on the firing con trol algorithms. The properties of Pulse Frequency Con trol (PFC) and Pulse Phase Control (PPC) are examined and small-signal discrete models are presented. These models are used in the analysis of constant current and constant extinction angle control through the z-transform method.

Alegria, C.M.; Freris, L.L.; Paiva, J.P.

1984-08-01

264

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)

1990-01-01

265

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)

1990-01-01

266

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

267

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

268

Radiation-Tolerant DC-DC Converters  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

269

Stimulation of reproductive activity in anovulatory Alpine goats exposed to bucks treated only with artificially long days.  

PubMed

Two experiments were conducted in a subtropical latitude to determine the response of Alpine male goats to a treatment with artificially long days (experiment 1), and the response of anovulatory lactating Alpine does exposed to males treated only with artificially long days (experiment 2). In experiment 1, one group of males was kept under natural photoperiod (n = 4) while another was exposed to 2.5 months of artificially long days (16 h of light/day) from 1 December (n = 4). Plasma testosterone concentrations were determined weekly. Intensity of odor of males was determined every 2 weeks. Sexual behavior of bucks was observed during 3 days about 90 days after the end of the long day treatment. A treatment-by-time interaction was detected for testosterone secretion (P < 0.001). In control males, low plasma concentrations of testosterone were observed from March to June. In contrast, in long-day treated males, high levels of testosterone were observed from March to June (P < 0.05). A treatment-by-time interaction was detected for the intensity of male odor (P < 0.01). The male odor was stronger in long-day treated bucks than in untreated ones from March to June (P < 0.05). The number of ano-genital sniffing, nudging and flehmen was greater in long-day treated males than in untreated ones when exposed to anestrous does (P < 0.05). In experiment 2, one group of males was left under natural photoperiod variations (n = 5) and the other (n = 5) was submitted to the same photoperiodic treatment described in experiment 1. On 3 May, three untreated and three long-day treated males were put in contact with anestrous Alpine does left under natural photoperiod. Fertility was higher in does exposed to light-treated males (36/45, 80%) than those in contact with untreated ones (3/45, 7%; P < 0.05). Prolificacy was similar (P > 0.05) in does exposed to treated (1.8 ± 0.1) and untreated males (1.7 ± 0.3). These results indicate that the sexual activity of Alpine male goats raised in subtropical latitudes can be induced using only artificially long days and that such males are effective in stimulating reproductive activity in anovulatory females in late spring. PMID:22445375

Delgadillo, J A; Vélez, L I

2010-12-01

270

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

271

Gadolinium sheet converter for neutron radiography.  

PubMed

This work describes a methodology developed for the confection of gadolinium sheet converter for neutron radiography using the gadolinium chloride (GdCl3) as material converter. Though manufactured at a relatively low cost, they are as good as the sheet converter on the market. Here, we present neutron radiography of the penetrameter, the edge spread function, the modulation transfer function and characteristic curves for each set sheet-AA400 Kodak film. PMID:17702586

Lima, C T S; Crispim, V R; Santos, W M S

2007-12-01

272

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

273

On configurable oversampled A/D converters  

SciTech Connect

This abstract presents a configurable oversampled A/D converter that can be either configured as a sigma-delta converter or an incremental converter. The latter refers to oversampled instrumentation converters that cancel offset and 1/f noise. The converter architecture is based on a new concept called mixed analog-digital integrator (MADI). As will be demonstrated in this paper, this concept leads to a very simple and modular architecture. In addition to the configurability as a sigma-delta or incremental converter, the implemented converter allows selection of the converter order and the decimation factor in order to find the best trade-off between resolution, conversion time or bandwidth, and power consumption. As the converter architecture is completely modular, it can rapidly be tailored for a specific application with minimized silicon area. The circuit achieves a resolution of 16 b on a range of [plus minus]650 mV and compensates the offset and the even-order harmonics to a nonobservable level.

Nys, O.J.; Dijkstra, E. (Swiss Center for Electronics and Microtechnology, Neuchatel (Switzerland))

1993-07-01

274

DC/DC Converter Stability Testing Study  

NASA Technical Reports Server (NTRS)

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

Wang, Bright L.

2008-01-01

275

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

276

Peak power tracking in parallel connected converters  

Microsoft Academic Search

A control scheme for parallel-connected converter systems that will transfer the maximum available power from a nonideal voltage source is presented. Monitoring the rates of change in both the average input current and the average input power from the source, the proposed control scheme can dynamically regulate the DC-DC converter system to track the peak power point of the source.

K. Siri; V. A. Caliskan; C. Q. Lee; G. C. Agarwal

1992-01-01

277

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

278

Radioisotope Thermionic Converters for Space Applications  

Microsoft Academic Search

The recent history of radioisotope thermionics is reviewed, with emphasis on the US. programs, and the prospects for the future are assessed. In radioisotope thermionic converters the emitter heat is generated by the decay of a radioactive isotope. The thermionic converter emitter is mounted directly on a capsule containing the isotope. The rest of the capsule is generally insulated to

Gabor Miskolczy; David P. Lieb

1990-01-01

279

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

280

New control strategy for matrix converter  

Microsoft Academic Search

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

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

1989-01-01

281

Randomized modulation in power electronic converters  

Microsoft Academic Search

This article reviews analytical results and practical experience with randomized modulation in power electronic converters. After providing a brief overview of power electronics and of relevant switching patterns, the authors present performance specifications for converters (in terms of electromagnetic interference, vibrations and acoustic noise), and classify various randomized switching schemes. They review the most directly related references next, and introduce

ALEKSANDAR M. STANKOVIC; HANOCH LEV-ARI

2002-01-01

282

GaN betavoltaic energy converters  

Microsoft Academic Search

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

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

2005-01-01

283

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

284

European Converts to Islam: Mechanisms of Radicalization  

Microsoft Academic Search

While European converts to Islam represent only a tiny percentage of Europe's Muslim population, members of that group have participated in major Islamist terrorist plots and attacks on European soil. Although the radicalization process has not been the same for all individuals, it could be still possible to understand the circumstances under which some European converts turned to violence. Therefore,

Emmanuel Karagiannis

2012-01-01

285

ZETA converter applied in power factor correction  

Microsoft Academic Search

This paper presents the analysis of the ZETA converter operating in discontinuous conduction mode (DCM) for power factor correction. The main attraction of the ZETA converter is that it is a naturally isolated structure, which allows a regulated output voltage with only one power processing stage. The principle of operation, mathematical analysis, design procedure and experimental results obtained from a

ADRIANO PERES; DENIZAR CRUZ MARTINS; I. Barbi

1994-01-01

286

RF digital-to-analog converter  

DOEpatents

A digital-to-analog converter is disclosed for producing an RF output signal proportional to a digital input word of N bits from an RF reference input, N being an integer greater or equal to 2. The converter comprises a plurality of power splitters, power combiners and a plurality of mixers or RF switches connected in a predetermined configuration. 18 figs.

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

1995-02-28

287

The auxiliary resonant commutated pole converter  

Microsoft Academic Search

The auxiliary resonant commutated pole (ARCP), a new power converter topology that fully achieves soft switching without increasing primary device voltage or current ratings, is discussed. The ARCP converter is capable of true pulse-width modulation (PWM) control of each phase. The power circuit relies on the addition of an auxiliary triggered resonant commutation circuit or snubber to commutate the inductive

R. W. De Doncker; J. P. Lyons

1990-01-01

288

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

NASA Technical Reports Server (NTRS)

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

Lee, F. C.

1980-01-01

289

Boost matrix converters in clean energy systems  

NASA Astrophysics Data System (ADS)

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

Karaman, Ekrem

290

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

291

Operation of high power converters in parallel  

NASA Technical Reports Server (NTRS)

High power converters that are used in space power subsystems are limited in power handling capability due to component and thermal limitations. For applications, such as Space Station Freedom, where multi-kilowatts of power must be delivered to user loads, parallel operation of converters becomes an attractive option when considering overall power subsystem topologies. TRW developed three different unequal power sharing approaches for parallel operation of converters. These approaches, known as droop, master-slave, and proportional adjustment, are discussed and test results are presented.

Decker, D. K.; Inouye, L. Y.

1993-01-01

292

Changes in testicular development, ultrasonographic and histological appearance of the testis in buck kids immunized against LHRH using recombinant LHRH fusion protein.  

PubMed

This study was designed to evaluate the effectiveness of recombinant Ovalbumin-LHRL (OL) immunization on changes in testicular size, histological appearance and testosterone production in buck kids. Thirty native buck kids at 18 weeks of age were divided into three groups, control (n = 10), immunization (n = 10) and castration (n = 10) groups. Immunized animals received OL protein generated by recombinant DNA technology. Ultrasonographic and histological examinations of the testes were performed. Animals were slaughtered at 44 weeks of age. Semen and epididymides were evaluated for the presence of sperm cells. Immunized animals generated anti-LHRH antibodies. Testosterone production, testicular and accessory glands development and sperm production were suppressed in the immunized animals (p < 0.01). Semineferous tubule diameters decreased (p < 0.01), basal membrane of the tubule was thickened and hyalinized in immunized kids. Immunization affected ultrasonographic appearance of the testes drastically. While testes of control animals gained their normal ultrasonographic appearance as the age increased, immunized animals had uniform hypoechogenic testicular structure as observed at 18 weeks of age until slaughter. Simultaneous histological and ultrasonographic evaluations indicated that the changes in testicular histology could partly be monitored via ultrasonographic imaging; nevertheless, it is difficult to claim that ultrasonographic image reflects the exact changes in such instances. In conclusion, these results indicate that recombinant OL fusion protein is effective in immunocastration in buck kids and has a potential to be used as an alternative to physical castration. Further researches should be conducted to help assessing reproductive status of testes from ultrasound images. PMID:18507800

Ulker, H; Küçük, M; Yilmaz, A; Yörük, M; Arslan, L; deAvila, D M; Reeves, J J

2009-02-01

293

Fertility results after vaginal deposition of frozen-thawed buck semen diluted with two different extenders using one- or two-step procedures.  

PubMed

In two field trials (T1 and T2), the effect of two different extenders for buck semen was tested. Semen from six (T1) and seven (T2) bucks of the Norwegian Dairy Goat breed was diluted either in a milk-based extender containing egg yolk (M) or in a commercially available extender without egg yolk [Andromed(®) (A)]. Dilution in M was performed in a two-step procedure including centrifugation of the ejaculates and removal of the supernatant, while dilution in A was performed in one step. During the two trials (T1 and T2) 514 and 714, does, respectively, were artificially inseminated during natural oestrus, and the farmers performed the inseminations themselves after attending an artificial insemination (AI) training course. Vaginal insemination with 200 × 10(6) spermatozoa diluted in M resulted in a 25-day non-return rate (NRR) and kidding rate of 37.3% and 24.5%, respectively, while semen diluted in A resulted in 31.7% NRR and a kidding rate of 19.8% (T1). In T2, NRR and kidding rate for AI performed with semen diluted with M were 42.7% and 28.5%, respectively, while dilution in A gave 37.2% NRR and a kidding rate of 26.8%. There was no significant effect of extender in the two trials [T1:p=0.068 (NRR), p=0.148 (kidding rate), T2:p=0.096 (NRR), p=0.38 (kidding rate)], but farmer had a significant effect on the fertility parameters in both trials. In conclusion, the present studies may indicate that Andromed(®) is suitable for buck semen. However, more research is necessary to confirm the results and to improve the fertility of does after vaginal AI with frozen-thawed semen. PMID:20210882

Nordstoga, A B; Söderquist, L; Adnøy, T; Paulenz, H

2011-02-01

294

Microfabricated coupled inductors for integrated power converters  

NASA Astrophysics Data System (ADS)

A microfabricated coupled inductor for low-voltage, high-current power converters is presented. The aim is to miniaturize such converters and improve their transient response using high-performance microfabricated inductors. These inductors have high power density enabled by a high-flux-density magnetic material (NiFe) and have the potential for integration with silicon circuits. A four-phase magnetically coupled structure with 14 nH of inductance per phase has been fabricated on silicon and implemented in a 5 MHz, 5-1 V, 4 A DC-DC converter. The coupled structure consists of four adjacent U-shaped copper windings sandwiched between two layers of NiFe. Electrical measurements match well with predictions for the converter.

Prabhakaran, Satish; O'Donnell, Terence; Sullivan, Charles R.; Brunet, Magali; Roy, Saibal; O'Mathuna, Cian

2005-04-01

295

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

296

Efficiency optimization of a thermionic converter array  

NASA Technical Reports Server (NTRS)

Intensive study of the outer planets of the solar system requires the use of nuclear power for electric propulsion of spacecraft. Among the power conversion devices being considered for this application are thermionic converters. This paper presents the results of computer modeling of thermionic converters to identify the major design variables and select an optimum size for each of the thermionic converters for the power conversion system under consideration. Among the variables investigated were electrical and thermal losses in electrodes, leads and heat chokes. Those elements which minimized the electrical losses tended to increase thermal losses and system weight. Overall mechanical design and relative positioning of components also had impacts on converter efficiency and the power subsystem weight. Numerical calculations were made using the computer heat transfer code SINDA coupled with electrical loss parameters. The results of the computations are presented in this paper.

Kuo, Y. S.; Phillips, W. M.

1979-01-01

297

Pipelined oversampling analog-to-digital converters  

E-print Network

Oversampling and noise-shaping techniques, such as [delta sigma] modulation, are widely used in analog-to-digital conversion to achieve accuracy that exceeds that of integrated-circuit components. Such converters have an ...

Paul, Susanne A. (Susanne Anita)

2003-01-01

298

Integrated optical analog-to-digital converter  

E-print Network

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

Khilo, Anatol

2008-01-01

299

Integrated photonic analog-to-digital converters  

E-print Network

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

Khilo, Anatol (Anatol M.)

2011-01-01

300

Rotorcraft convertible engines for the 1980s  

NASA Technical Reports Server (NTRS)

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

Eisenberg, J. D.

1982-01-01

301

Radio frequency digital to analog converter  

E-print Network

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

Luschas, Susan, 1975-

2003-01-01

302

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. PMID:22410787

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

2014-01-01

303

"Forback" Dc-To-Dc Converters  

NASA Technical Reports Server (NTRS)

Dc-to-dc power-converter circuits called "forback" resemble circuits of standard configurations called "forward", "flyback", and "Cuk". Circuit employs minor modifications to existing topologies, combines advantages, while eliminating disadvantages, of older circuits.

Lukemire, Alan T.

1992-01-01

304

Active-clamping quad-flyback converter  

Microsoft Academic Search

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

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

2009-01-01

305

Use of Reactance with Synchronous Converters  

Microsoft Academic Search

The paper presents the results of overload and short-circuit tests made about two years ago upon some synchronous converters in circuit with auxiliary reactors. Two entirely separate sets of tests upon two synchronous converters of widely different operating characteristics are described. In the one case the reactor is in the a-c. circuit and in the other in the d-c. circuit;

J. L. Mc K. Yardley

1914-01-01

306

An accurate voltage-to-frequency converter  

Microsoft Academic Search

A current- or voltage-to-frequency converter is described for converting analogue signals into a pulse form in which the pulse repetition frequency is proportional to the instantaneous signal amplitude. The conversion is linear to within 0·01% over the frequency range 0-10 kHz (or 0-1 kHz), and to within 0·1% up to 50 kHz. Thermal stability is comparable.The circuit action is based

P J Unsworth

1969-01-01

307

Novel zero-current-switching PWM converters  

Microsoft Academic Search

This paper presents a new family of pulsewidth-modulated (PWM) converters, featuring soft commutation of the semiconductors at zero current (ZC) in the transistors and zero voltage (ZV) in the rectifiers. Besides operating at constant frequency and with reduced commutation losses, these new converters have output characteristics similar to the hard-switching-PWM counterpart, which means that there is no circulating reactive energy

Carlos A. Canesin; Ivo Barbi

1997-01-01

308

16 CFR 802.31 - Acquisitions of convertible voting securities.  

...2014-01-01 false Acquisitions of convertible voting securities. 802.31 Section 802.31... § 802.31 Acquisitions of convertible voting securities. Acquisitions of convertible voting securities shall be exempt from the...

2014-01-01

309

16 CFR 802.31 - Acquisitions of convertible voting securities.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Acquisitions of convertible voting securities. 802.31 Section 802.31... § 802.31 Acquisitions of convertible voting securities. Acquisitions of convertible voting securities shall be exempt from the...

2010-01-01

310

31 CFR 800.206 - Convertible voting instrument.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Convertible voting instrument. 800.206 Section 800.206...PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument...

2010-07-01

311

31 CFR 800.206 - Convertible voting instrument.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Convertible voting instrument. 800.206 Section 800.206...PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument...

2012-07-01

312

31 CFR 800.206 - Convertible voting instrument.  

...2014-07-01 2014-07-01 false Convertible voting instrument. 800.206 Section 800.206...PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument...

2014-07-01

313

16 CFR 802.31 - Acquisitions of convertible voting securities.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Acquisitions of convertible voting securities. 802.31 Section 802.31... § 802.31 Acquisitions of convertible voting securities. Acquisitions of convertible voting securities shall be exempt from the...

2013-01-01

314

31 CFR 800.206 - Convertible voting instrument.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Convertible voting instrument. 800.206 Section 800.206...PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument...

2011-07-01

315

16 CFR 802.31 - Acquisitions of convertible voting securities.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Acquisitions of convertible voting securities. 802.31 Section 802.31... § 802.31 Acquisitions of convertible voting securities. Acquisitions of convertible voting securities shall be exempt from the...

2011-01-01

316

16 CFR 802.31 - Acquisitions of convertible voting securities.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Acquisitions of convertible voting securities. 802.31 Section 802.31... § 802.31 Acquisitions of convertible voting securities. Acquisitions of convertible voting securities shall be exempt from the...

2012-01-01

317

31 CFR 800.206 - Convertible voting instrument.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Convertible voting instrument. 800.206 Section 800.206...PERSONS Definitions § 800.206 Convertible voting instrument. The term convertible voting instrument means a financial instrument...

2013-07-01

318

Effects of different extenders and centrifugation/washing on postthaw microscopic-oxidative stress parameters and fertilizing ability of Angora buck sperm.  

PubMed

The main objective of the current study was to evaluate the effects of extender type and centrifugation/washing prior to cryopreservation on the postthaw sperm parameters, lipid peroxidation, and superoxide dismutase activity of Angora buck (Capra hircus ancryrensis) sperm. Ejaculates collected from three Angora bucks were used in this study. Two consecutive ejaculates from each buck were pooled and split into equal parts in four Falcon tubes. Two tubes were diluted at 37 degrees C and then centrifuged to remove semen plasma. After centrifugation, two sediment parts were diluted with a Tris-based extender and commercial Bioxcell extender, respectively. The remaining two parts, which were not centrifuged/washed, were diluted with the above-mentioned extenders, respectively. Diluted samples were cooled to 5 degrees C and frozen in 0.25-mL French straws to be stored in liquid nitrogen. Frozen straws were thawed individually at 37 degrees C for 20 sec in a water bath for evaluation. The semen part with centrifugation/washing in the Bioxcell extender (BC) demonstrated a higher rate of subjective motility (58.1+/-3.0%) compared with that of groups with (TC) or without (T) centrifugation/washing in the Tris-based extender (P<0.01). Angora buck sperm frozen with (BC) or without (B) centrifugation/washing in the Bioxcell extender demonstrated higher percentages of motility (60.6+/-2.7% and 54.3+/-4.8%, respectively) compared with that of groups T and TC. The postthaw progressive motility rate (22.3+/-2.7%) was significantly greater for semen parts diluted in B compared with that of other groups. BC gave rise to a lower value of average path velocity (90.0+/-5.2 microm/sec) compared with that of other groups (P<0.01). For straight linear velocity and linearity index, the highest values (103.2+/-4.7 microm/sec, 47.5+/-1.6% and 94.8+/-3.0 microm/sec, 44.8+/-1.1%, respectively) were obtained from B and TC (P<0.001). For sperm acrosome and total abnormalities, TC gave the highest values (11.2+/-0.6% and 26.6+/-1.5%, respectively, P<0.01). In the group frozen in BC, the percentage of membrane integrity assessed by hypo-osmotic swelling test was higher (61.2+/-2.2%) than that of the other groups (P<0.001). With respect to fertility results based on 35-d pregnancy rates, BC gave a higher rate (76.5%) than that of TC (27.8%, P<0.05). Malondialdehyde formation was found to be lower (1.64+/-0.26 nmol/L) in BC than in the other groups after the freeze-thawing process (P<0.001). In the semen part frozen in BC, superoxide dismutase activity was higher (0.18+/-0.02 U/mg protein) compared with that of the other groups (P<0.05). Further studies are required to obtain more precise results for the characterization of oxidative stress parameters and fertilizing ability in cryopreserved buck spermatozoa. PMID:19880169

Sariözkan, S; Bucak, M N; Tuncer, P B; Ta?demir, U; Kinet, H; Uluta?, P A

2010-02-01

319

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

320

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

321

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

322

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?

323

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

324

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

325

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

326

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

327

Converting Centrifugal Chillers to HCFC-123  

E-print Network

of large water chillers in addressing the CFC issue. These owners, for a variety of reasons, chose to address the issue through the conversion of the existing equipment to an HCFC refrigerant. For each of the three owners, the option of converting...

Siebert, B.

328

Does nature convert mass into energy?  

Microsoft Academic Search

First I provide some history of how the equation E=mc2 arose, establish what ``mass'' means in the context of this relation, and present some aspects of how the relation can be understood. Then I address the question, Does E=mc2 mean that one can ``convert mass into energy'' and vice versa?

Ralph Baierlein

2007-01-01

329

A digitalized voltage-to-frequency converter  

Microsoft Academic Search

A new voltage-to-frequency converter, controlled by a quartz crystal oscillator, is described. The principle of operation is based on comparing the input voltage and the mean value of the output pulses, whose magnitude and duration are constant. As the duration of the output pulses is a multiple of the quartz oscillator period for any value of the input voltage, the

B. Ž DJORDJEVICH

1975-01-01

330

Converting Dependency Structures to Phrase Structures  

Microsoft Academic Search

Abstract: this paper, we address the relationshipbetween dependency structures and phrase structures from a practicalperspective; namely, the exploration of different algorithms thatconvert dependency structures to phrase structures and the evaluationof their performance against an existing Treebank. This worknot only provides ways to convert Treebanks from one type of representationto the other, but also clarifies the differences in representationalcoverage of the

Fei Xia; Martha Palmer

2001-01-01

331

A new generalized direct matrix converter  

Microsoft Academic Search

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

S. H. Hosseini; E. Babaei

2001-01-01

332

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

333

Multilevel converters for large electric drives  

SciTech Connect

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

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

1997-11-01

334

Materials technology for Stirling space power converters  

Microsoft Academic Search

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

William Baggenstoss; Donald Mittendorf

1992-01-01

335

Fuel Cells as Clean Energy Converters  

Microsoft Academic Search

A fuel cell is a device in which the energy of a fuel is converted directly into electricity direct current by an electrochemical reaction without resorting to a burning process, rather than to heat by a combustion reaction. The chemical energy of the fuel is released in the form of an electrical energy instead of heat when the fuel is

A. Demirbas

2007-01-01

336

Status of research on advanced thermionic converters  

Microsoft Academic Search

It is shown that it is possible to controllably and continuously elevate the electron temperature in the plasmatron thermionic energy converter from the emitter temperature to the maintenance electron temperature for the diode arc mode. This ability and the apparent validity of an elementary analytical model of the plasma should make possible the optimization and evaluation of operation under strong

G. L. Hatch; W. Rhiner; N. S. Rasor; L. K. Hansen

1977-01-01

337

Convertible Shoes: Function, Fashion and Design  

NSDL National Science Digital Library

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

Integrated Teaching And Learning Program

338

Quasi-square-wave converters: topologies and analysis  

Microsoft Academic Search

A class of converters with zero-voltage or zero-current switching characteristics is analyzed using a method originally developed for quasiresonant and PWM (pulsewidth-modulated) converters. The method relies on identifying simple three-terminal structures, called converter sections, that contain the switches and the resonant tank elements. The various zero-voltage-switched and zero-current-switched converters are obtained by permutation of these converter sections between source and

VATCHE VORPERIAN

1988-01-01

339

Emissions Tests Of Two Dc-To-Dc Converters  

NASA Technical Reports Server (NTRS)

Report describes tests to characterize unwanted electric and magnetic fields, at frequencies up to few megahertz, radiated by two dc-to-dc converters, one 20-kHz square-wave converter; the other, a 33-kHz sine-wave converter. Part of effort to develop "quiet" power converter for use aboard spacecraft. Converter required to interfere minimally with delicate instruments measuring electric and magnetic fields.

Mclyman, W. T.

1992-01-01

340

The buck stops here.  

PubMed

As Allegheny Health, Education and Research Foundation muddles through its high-profile bankruptcy reorganization, the spotlight of public scrutiny is now shining brightly on the system's board members, who were supposed to act as guardians of the not-for-profit system. "When things fall apart, the board members usually take the heat," says one governance expert. "And they should take the heat, since they are the final buffer." PMID:10183050

Shinkman, R

1998-08-01

341

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

342

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

343

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

E-print Network

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

Bieniosek, Matthew (Matthew F.)

2010-01-01

344

The value of the percentage of motile sperm in predicting a significant portion of the fertility variation of frozen-thawed buck semen.  

PubMed

Prediction of the future fertility of a given ejaculate with a simple laboratory test is still considered a real issue in domestic mammal breeding. This study showed that a subjective assessment of the percentage of motile spermatozoa, measured 120 min after thawing (mob120), can predict a significant part (?50%) of the variation of the future fertility of buck ejaculates. The predictive model was calculated using a calibration data set composed of 40 ejaculates from four Alpine and six Saanen bucks. A fertility trial using split ejaculates was conducted in order to estimate ejaculate fertility. Taken into account were the herd within breed factor and the year, month, and inseminator factors. On average, one ejaculate was used to inseminate two females per herd in 10 different herds. This calibration set allowed us to choose the mob120 variable among a set of laboratory tests: mitochondrial activity, acrosomal status, membrane integrity, osmotic resistance test assessed by flow cytometry, velocity and motion characteristics assessed by computer-assisted sperm analysis, visually assessed percentage of motile, and motility score measured 5 and 120 min after thawing. For the calibration step, the best model used the logarithm of mob120 and gave a correlation coefficient of 0.71 between the field fertility and the predicted fertility and a standard error of 0.17. We tested this model on 3 different validation data sets adding up to 95 ejaculates that were all different from those of the calibration data set. The correlation coefficients between field fertility and predicted fertility were always significant and the bias corrected standard error ranged from 0.15 to 0.18 on these validation data sets. A Monte Carlo simulation showed that about 20% of the fertility variation remained to be explained. PMID:20615534

Furstoss, V; Borderes, F; Forgerit, Y; Guillouet, P; Leboeuf, B

2010-10-15

345

Influence of the preservation temperature (37, 20, 4, -196°C) and the mixing of semen over sperm quality of Majorera bucks.  

PubMed

This study assessed the effect of different semen storage temperatures and the influence of semen pooling in semen viability. In experiment 1, semen samples (n = 30) of five Majorera bucks were individually processed [Individual semen (IS)] and after the first dilution (Tris-yolk extender), semen-diluted aliquots from each male were pooled semen (PS). Thereafter, semen samples (IS and PS) were preserved as fresh semen (37 and 20°C), chilled semen (4°C) and frozen semen. Sperm motility and the percentage of abnormal sperm cells and intact membrane acrosomes were defined. Semen preservation at 20 and 4°C did not modify the quality of spermatozoa for the first 24 h, but the conservation at 37°C caused a dramatic fall in the semen motility from 12 h onwards. Furthermore, the longevity of frozen-thawed semen was limited to 4-6 h. No differences were observed in semen parameters when PS was compared with semen from individual males in any of the preservation protocols assessed. In experiment 2, 120 goats were distributed in four experimental groups: in group fresh individual semen (FIS, n = 30) and group frozen-thawed individual semen (FTIS, n = 30), does were transcervically inseminated with fresh semen and frozen-thawed semen from each individual male, respectively, and in group fresh pooled semen (FPS, n = 30) and group frozen-thawed pooled semen (FTPS, n = 30), goats were transcervically inseminated with FPS and FTPS, respectively. The kidding rate was very close in the FIS and FPS groups (70.0% and 73.7%, respectively), and no significant differences were observed in the fertility rate between FTIS and FTPS. The results of this study confirmed that semen samples may be preserved satisfactorily for 24 h both at 20 and 4°C. In addition, the mixture of semen of different bucks did not significantly modify the semen parameters when compared with semen from individual males. PMID:20565698

Batista, M; Niño, T; Santana, M; Alamo, D; Castro, N; Reyes, R; González, F; Cabrera, F; Gracia, A

2011-04-01

346

Effect of semen collection method (artificial vagina vs. electroejaculation), extender and centrifugation on post-thaw sperm quality of Blanca-Celtibérica buck ejaculates.  

PubMed

The aim of this study was to evaluate the effect of semen collection method (artificial vagina compared to electroejaculation), season in which the semen was collected (breeding season compared to non-breeding season), freezing extender (Biladyl(®), Andromed(®) and skim milk based extender) and pre-treatment procedure (washing compared to non-washing) on post-thaw semen quality in buck. Ejaculates from seven bucks of the Blanca-Celtibérica breed were collected by artificial vagina and electroejaculation during the breeding (July to December) and non-breeding season (January to June). Samples were split in two aliquots and one of them was washed. Three freezing extenders were evaluated on washing and non-washing sperm samples. Ejaculates collected by artificial vagina had a greater sperm quality after thawing, with greater values (P?0.05) for SM (sperm motility), NAR (acrosome intact), YO-PRO-1-/PI- (intact spermatozoa), and Mitotracker+/YO-PRO-1- (spermatozoa with active mitochondria) and lower % DFI (DNA fragmentation index). Thawed sperm samples which were collected during the breeding season had greater values (P?0.05) for NAR, intact spermatozoa and spermatozoa with active mitochondria, than those semen samples obtained during the non-breeding season. Semen freezing with Biladyl(®) and Andromed(®) resulted in a greater sperm quality (P?0.05) after thawing in relation to milk-based extender. Washing procedure had no effect on sperm parameters assessed at thawing. Results from the present study suggest that the success of semen cryopreservation in Blanca-Celtibérica goat depends on semen collection method and season, as well as on the extender used. Thus, the post-thaw sperm quality will be greater (P?0.05) when samples are collected by artificial vagina during the breeding season and when Biladyl(®) or Andromed(®) are used as freezing extenders. PMID:22572556

Jiménez-Rabadán, P; Ramón, M; García-Álvarez, O; Maroto-Morales, A; del Olmo, E; Pérez-Guzmán, M D; Bisbal, A; Fernández-Santos, M R; Garde, J J; Soler, A J

2012-05-01

347

Digitally programmable voltage-to-frequency converter  

NASA Astrophysics Data System (ADS)

The author presents a novel design approach for a VFC (voltage-to-frequency converter) based on a digital technique which utilizes an analog-to-digital converter, programmable read-only-memory, latch, divide-by-n chip, and associated control circuitry. The unique aspect of this design is the fact that the ratio between the maximum and minimum frequency rates is programmable by the user, and the performance is highly repeatable. This technique was developed in order to provide a drive circuitry for a 5-b digital phase shifter which was being serrodyned in order to create deception jamming functions for electronic countermeasures applications. A circuit diagram of the digital VFC is presented.

Madni, Asad M.

348

Fundamental study on alkali metal thermoelectric converter  

NASA Astrophysics Data System (ADS)

The alkali metal thermoelectric converter (AMTEC), which utilizes the sodium ion conducting beta-double prime-alumina, is a device for directly converting heat energy to electric energy. It is characterized by high conversion efficiencies of 20 to 40 percent, high power densities of 1 W/sq cm, no moving parts, low maintenance requirements, high durability, and efficiency independent of size. Because of these merits, AMTEC is one of the most promising candidates for dispersed small-scale power stations, remote power stations, and aerospace power systems. In this paper, the results of theoretical and experimental studies on AMTEC power generating characteristics, internal electrical resistances of single cells, and system analysis of AMTEC power-generating systems are reported.

Masuda, Toshihisa

1989-11-01

349

Strained quantum well photovoltaic energy converter  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

350

MAGIC: Model and Graphic Information Converter  

NASA Technical Reports Server (NTRS)

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

Herbert, W. C.

2009-01-01

351

Real power measurement using a thermal converter  

NASA Astrophysics Data System (ADS)

In this paper, a new application of thermal converters is presented which allows energy, power and rms measurement without the need to substitute the measurement signal with a dc signal as performed in ac-dc transfer. Using a mathematical model of standard planar multijunction thermal converters (PMJTCs), the effective power acting inside the heater of the PMJTC is calculated from the output signal of its thermocouples. Due to the underlying physical principles, this method not only allows the calculation of the rms value of sinusoidal signals but also the average power and absolute energy contained in non-sinusoidal, non-periodic and even non-stationary signals, as appearing in the characterization of energy harvesters.

Möhring, Tobias; Spiegel, Thomas; Funck, Torsten

2014-03-01

352

Status of research on advanced thermionic converters  

NASA Technical Reports Server (NTRS)

It is shown that it is possible to controllably and continuously elevate the electron temperature in the plasmatron thermionic energy converter from the emitter temperature to the maintenance electron temperature for the diode arc mode. This ability and the apparent validity of an elementary analytical model of the plasma should make possible the optimization and evaluation of operation under strong ionization conditions for which the plasma resistance should be acceptably low. Measurement of the vacuum space charge arising from the emission from a surface in cesium vapor indicates the presence of a substantial negative ion emission current. Apparatus has been constructed for identifying and directly measuring the flux of positive, negative and neutral species emitted from an electrode surface in a cesium vapor diode. The primary purpose of the investigation is to determine the influence of negative ion emission on the effective work function of thermionic converter electrodes. Initial data indicate the presence of H(-), Cs(-) and possibly C(-) and CH(-).

Hatch, G. L.; Rhiner, W.; Rasor, N. S.; Hansen, L. K.

1977-01-01

353

Superconductor analog-to-digital converters  

Microsoft Academic Search

Ultrafast switching speed, low power, natural quantization of magnetic flux, quantum accuracy, and low noise of cryogenic superconductor circuits enable fast and accurate data conversion between the analog and digital domains. Based on rapid single-flux quantum (RSFQ) logic, these integrated circuits are capable of achieving performance levels unattainable by any other technology. Two major classes of superconductor analog-to-digital converters (ADCs)

OLEG A. MUKHANOV; DEEPNARAYAN GUPTA; ALAN M. KADIN; VASILI K. SEMENOV

2004-01-01

354

An overview of sigma-delta converters  

Microsoft Academic Search

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

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

1996-01-01

355

High precision voltage-to-frequency converter  

Microsoft Academic Search

A bipolar high precision voltage-to-frequency converter is described. The circuit includes an input voltage-to-current conversion stage followed by current-controlled multivibrator. The multivibrator trigger includes a window comparator with a limiter of the output voltage swing, and the timing capacitor discharge current is switched simultaneously with the window comparator bias. This allows to obtain high resolution near both trigger thresholds. The

Sidong Cai; I. M. Filanovsky

1994-01-01

356

Piezoelectric cantilever voltage-to-frequency converter  

Microsoft Academic Search

A micromachined piezoelectric cantilever acoustic device that functions as a microspeaker and a voltage-to-frequency converter has been designed, fabricated and tested. The 2 × 2 × 0.0047 mm3 cantilever has a 1.3-?m-thick zinc oxide (ZnO) piezoelectric thin film on a supporting layer of LPCVD low-stress silicon nitride. When measured with 8 VP-P (peak-peak) input drive, the sound pressure level (SPL)

Seung S. Lee; Richard M. White

1998-01-01

357

The New Bridge Converter Control Method  

NASA Astrophysics Data System (ADS)

The article describes a new control method of transistor power bridge converter. It is a new one, because of some original solutions and its difference in comparison to existing methods. It's irrelevant of load, similar to the "phase shifted" control method. It is easy to realize using ordinary electronic elements. A significant advantage of method is the possibility of permanent output current monitoring by measuring the voltage sag on a pair of transistors. That allows a very efficient current protection.

Radetic, R. M.; Milivojevic, D. R.; Pavlov, M.

2010-01-01

358

The Universal Currency Converter - Xenon Laboratories Incorporated  

NSDL National Science Digital Library

An interactive currency table. Versions are available in English, Spanish, and Swedish. The Universal Currency Converter⢠allows you to perform interactive foreign exchange rate conversion on the Internet. Type the amount of source currency in the input box. You may include commas and a decimal point. Select the source and destination currencies using the scrolling selection boxes. When you are finished, push the "Perform Currency Conversion" button, and the results of your conversion will be displayed.

2007-03-01

359

7 CFR 12.32 - Converted wetland identification criteria.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

360

7 CFR 12.32 - Converted wetland identification criteria.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

361

7 CFR 12.32 - Converted wetland identification criteria.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

362

7 CFR 12.32 - Converted wetland identification criteria.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

363

Nuclear Fuel (Carbide) Clad Thermionic Converters. Volume 1.  

National Technical Information Service (NTIS)

Thermionic converters fueled with Re-clad carbide cermets were studied in this program. Two thermionic modules, each module being an assembly of two series-connected converters with a single common cesium reservoir, were designed, fabricated, and tested. ...

C. K. Smith

1965-01-01

364

Automated Synthesis Tool for Design Optimization of Power Electronic Converters  

E-print Network

module-integrated photovoltaic inverter is also optimized for efficiency, volume and reliability. An actual converter is constructed using commercial off-the-shelf components. The converter design is chosen as close as possible to a point obtained...

Mirjafari, Mehran

2013-01-09

365

Asynchronous Design By Conversion: Converting Synchronous Circuits into Asynchronous Ones  

E-print Network

asynchronous circuit can adapt its effective operating frequency to the supply voltage, facilitating flexible1 Asynchronous Design By Conversion: Converting Synchronous Circuits into Asynchronous Ones Alex, and subsequently converted into an asynchronous one. The conversion algorithm consists of extracting input

Ginosar, Ran

366

A Laboratory Study of X-to-Frequency Converters.  

ERIC Educational Resources Information Center

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

Kartalopoulos, Stamatios V.

1979-01-01

367

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Convertibility of military payment certificates. 538.4 Section...DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For...

2013-07-01

368

32 CFR 538.4 - Convertibility of military payment certificates.  

...2014-07-01 false Convertibility of military payment certificates. 538.4 Section...DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For...

2014-07-01

369

Digital radix converters for high accuracy data conversion  

E-print Network

A sub-binary radix Digital to Analog converter(DAC) which achieves high effective resolution is demonstrated. The converter does not have any built-in-self calibration mechanisms, but achieves high resolution and accuracy through the sub...

Ghanta, Venkataratnam Chowdary

2012-06-07

370

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2012 CFR

...2009-07-01 true Convertibility of military payment certificates. 538.4 Section...DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For...

2012-07-01

371

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2011 CFR

...2009-07-01 true Convertibility of military payment certificates. 538.4 Section...DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For...

2011-07-01

372

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 true Convertibility of military payment certificates. 538.4 Section...DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For...

2010-07-01

373

Roobrix: Convert a student rubric score to a percentage  

NSDL National Science Digital Library

This website provides a method for converting any rubric score into a percentage. Users provide the basic information for how the rubric is scored and the site converts it into the appropriate percentage. This is a great tool for teachers.

2013-06-06

374

An economical single to three phase converter for induction motors  

E-print Network

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

Di Zerega, Philp Van Uytandaele

2012-06-07

375

High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype  

E-print Network

The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

Jørgensen, H E; Dupaquier, A; Fernqvist, G

1998-01-01

376

High Current, Low Voltage Power Converter [20kA, 6V] - LHC Converter Prototype  

NASA Astrophysics Data System (ADS)

The superconducting LHC accelerator requires high currents (approximately 12.5 kA) and relatively low voltages (approximately 10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA, 6V] power converter intended as a stable high-current source for DCCT calibration and an evaluation prototype for the future LHC converters. The converter is made up using a modular concept where five current sources [4kA, 6V] are placed in parallel. The 4 kA sources are configured in plug-in modules : a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage with high frequency transformers, Schottky rectifiers and output filters. The obtained performance (DC stability, bandwidth, efficiency, EMC,...) is presented and discussed.

Bordry, F.; Dupaquier, A.; Fernqvist, G.; Jorgensen, H. E.; Madsen, P.; Steinmann, E.

1997-05-01

377

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

NASA Technical Reports Server (NTRS)

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

Divan, Deepakraj M.

1990-01-01

378

Active-Clamping ZVS Flyback Converter Employing Two Transformers  

Microsoft Academic Search

This paper presents a two-transformer active-clamping zero-voltage-switching (ZVS) flyback converter, which is mainly composed of two active-clamping flyback converters. By utilizing two separate transformers, the proposed converter allows a low-profile design to be readily implemented while retaining the merits of a conventional single-transformer topology. The presented two-transformer active-clamping ZVS flyback converter can approximately share the total load current between two

Yu-Kang Lo; Jing-Yuan Lin

2007-01-01

379

Limiting efficiency of coupled thermal and photovoltaic converters  

Microsoft Academic Search

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

Antonio Luque; Antonio Mart??

1999-01-01

380

A comparison of half-bridge resonant converter topologies  

Microsoft Academic Search

The half-bridge series-resonant, parallel-resonant, and combination series-parallel resonant converters are compared for use in low-output-voltage power supply applications. It is shown that the combination series-parallel converter, which takes on the desirable characteristics of the pure series and the pure parallel converter, avoids the main disadvantages of each of them. Analyses and breadboard results show that the combination converter can run

R. L. Steigerwald

1988-01-01

381

Voltage balanced multilevel voltage source converter system  

DOEpatents

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

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

1997-07-01

382

Development and validation of pedestrian sedan bucks using finite-element simulations: a numerical investigation of the influence of vehicle automatic braking on the kinematics of the pedestrian involved in vehicle collisions  

Microsoft Academic Search

Previous vehicle-to-pedestrian impact simulations and experiments using pedestrian dummies and cadavers have shown that factors such as vehicle shape, pedestrian anthropometry and pre-impact conditions influence pedestrian kinematics and injury mechanisms. Generic pedestrian bucks, which approximate the geometrical and stiffness properties of current vehicles, would be useful in studying the influence of vehicle front-end structures on pedestrian kinematics and loading. This

Costin D. Untaroiu; Jaeho Shin; Jeff R. Crandall; Rikard Fredriksson; Ola Bostrom; Yukou Takahashi; Akihiko Akiyama; Masayoshi Okamoto; Yuuji Kikuchi

2010-01-01

383

Research on a Novel Interleaved Flyback DC\\/DC Converter  

Microsoft Academic Search

Flyback converter has been widely used in low-power applications because of its relative simplicity when compared with other topologies. This paper proposes a novel interleaved flyback DC\\/DC converter, which provides the additional benefit of recycling transformer leakage inductance energy and reducing voltage stress of the power switches. Its input and output current ripple is much smaller than basic flyback converter.

Hongmei Wang; Chunying Gong; Haixiao Ma; Yangguang Yan

2006-01-01

384

A practical method of harmonic analysis for power converter  

Microsoft Academic Search

The converter is one important harmonic source in power systems. For the knowledge of harmonic characteristics of a converter, it is very important to evaluate the harmonic situations of AC and DC sides, and also it is very helpful to design the harmonic filters and to suppress harmonic propagation. A practical method of harmonic evaluation for a power converter is

Jianguo Jiang; Weimin Xie; Juan Zhou

2000-01-01

385

Modeling and Analysis of Coupled Inductors in Power Converters  

Microsoft Academic Search

This paper describes a new approach to the analysis of switched mode power converters utilizing coupled inductors and presents a novel canonical circuit model for N-winding coupled inductors. Waveform and ripple of the winding current in a coupled inductor converter can be easily determined using the developed model similar to those obtained in an uncoupled inductor converter. Influence of coupling

Guangyong Zhu; Brent McDonald; Kunrong Wang

2009-01-01

386

LM2907LM2917FrequencytoVoltageConverter February 1995  

E-print Network

speed sensing Y Frequency to voltage conversion (tachometer) Y Speedometers Y Breaker point dwell metersTL H 7942 LM2907LM2917FrequencytoVoltageConverter February 1995 LM2907 LM2917 Frequency to Voltage Converter General Description The LM2907 LM2917 series are monolithic frequency to voltage converters

Wedeward, Kevin

387

Two-parameter bifurcation curves in power electronic converters1  

E-print Network

Two-parameter bifurcation curves in power electronic converters1 E. Fossas , S. J. Hogan§ and T. M-periodic response. 1Abbreviated Title: Bifurcations in power electronic converters 1 #12;1 Introduction Electronic by switched mode conversion in a circuit known as a power electronic converter. The basic idea

Politècnica de Catalunya, Universitat

388

Design of power converter for induction furnaces with computer simulations  

Microsoft Academic Search

In the paper researches for design of the resonant converter for induction heating of the metals by computer simulation programs are given. ELTA, PowerSim and Semesiel simulation programs are used for design and optimization in the power converter. The purpose of the research is work on bridge power converter in mode of induction device. The mode of induction heating of

Goce Stefanov; Ljupco Karadzinov; Dejan Karanfilov

2010-01-01

389

A TUNABLE-OUTPUT WAVELENGTH CONVERTER BASED ON A SELF-  

E-print Network

A TUNABLE-OUTPUT WAVELENGTH CONVERTER BASED ON A SELF- SEEDED FABRY-PEROT LASER DIODE ABSTRACT: We report a new all-optical wavelength conversion scheme based on a self-seeded Fabry­Perot laser diode with a chirped fiber grating as the external cavity. This converter can convert the wavelength

Choi, Woo-Young

390

Small signal equivalent circuit modeling of resonant converters  

Microsoft Academic Search

A general analytical procedure is presented for the equivalent circuit modeling of resonant converters, using the series and parallel resonant converters as examples. The switched tank elements of a resonant converter are modeled by a lumped parameter equivalent circuit. The tank element circuit model consists, in general, of discrete energy states, but may be approximated by a low-frequency continuous time

Arthur F. Witulski; Adhn F. Hernandez; Robert W. Erickson

1991-01-01

391

Converting information from paper to optical media  

NASA Technical Reports Server (NTRS)

The technology of converting large amounts of paper into electronic form is described for use in information management systems based on optical disk storage. The space savings and photographic nature of microfiche are combined in these systems with the advantages of computerized data (fast and flexible retrieval of graphics and text, simultaneous instant access for multiple users, and easy manipulation of data). It is noted that electronic imaging systems offer a unique opportunity to dramatically increase the productivity and profitability of information systems. Particular attention is given to the CALS (Computer-aided Aquisition and Logistic Support) system.

Deaton, Timothy N.; Tiller, Bruce K.

1990-01-01

392

A variable parameter thermionic energy converter  

E-print Network

A VARIABLE PARAMETER THERMIONIC ENERGY CONVERTER A Thesis By Bobby Joe Bragg Submitted to the Graduate School of the Texas A 8c M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August, 1967 Major... OUTPUT AF1'ER LOSS OF CESIUM 25. OUTPUT POWER VS SPACING& PRELIMINARY DATA 26. OUTPUT POWER VS SPACING, RUN NO. 1 27. OUTPUT POWER VS SPACING, KJN NO. 2 28. OUTPUT POWER VS SPACING& A. E. CAMPBELL DATA& REF. 1 29. OUTPUT POWER VS SPACING, RUN NO. 3...

Bragg, Bobby Joe

2012-06-07

393

Converting gravity bins to spherical harmonic coefficients  

NASA Technical Reports Server (NTRS)

The gravity bin technique as originally formulated recovers the local gravity field from the bin parameters by finite differencing. The spherical harmonic coefficients of the gravity field are then computed by an orthogonal transformation of the local gravity field. The result differs from that of the traditional method. This paper discusses the difference and proposes a new algorithm to convert the bin parameters to spherical harmonic coefficients. It is shown that the new method produces the same gravity field as the traditional method and maintains the high computational efficiency of the basic gravity bin technique.

Wu, J. T.; Bertiger, W. I.; Wu, S. C.

1990-01-01

394

A wideband 12 GHz down converter  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

395

Dead time optimization method for power converter  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

396

Development of switching peak current reduction method in switched-capacitor dc-dc converters to n-level converters  

Microsoft Academic Search

The dc-dc converters are used in wide variety of industrial applications. Common traditional dc-dc converters require at least one inductive component which makes them bulky, costly, and with low efficiency. Switched-capacitor (SC) dc-dc converters are a solution that can overcome these problems. However, these converters have high pulse currents when switching transients occur, which will reduce the efficiency and cause

Ebrahim Babaei; Mohammad Nilkar; Meisam Sadeghi

2011-01-01

397

Input-current shaped ac to dc converters  

NASA Technical Reports Server (NTRS)

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

1986-01-01

398

Resonant Tunneling Analog-To-Digital Converter  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

399

Forback DC-to-DC converter  

NASA Technical Reports Server (NTRS)

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

Lukemire, Alan T. (inventor)

1993-01-01

400

Forback DC-to-DC converter  

NASA Technical Reports Server (NTRS)

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

Lukemire, Alan T. (inventor)

1995-01-01

401

Analysis of self-oscillating dc-to-dc converters  

NASA Technical Reports Server (NTRS)

The basic operational characteristics of dc-to-dc converters are analyzed along with the basic physical characteristics of power converters. A simple class of dc-to-dc power converters are chosen which could satisfy any set of operating requirements, and three different controlling methods in this class are described in detail. Necessary conditions for the stability of these converters are measured through analog computer simulation whose curves are related to other operational characteristics, such as ripple and regulation. Further research is suggested for the solution of absolute stability and efficient physical design of this class of power converters.

Burger, P.

1974-01-01

402

A novel unipolar converter for switched reluctance motor  

NASA Astrophysics Data System (ADS)

A configuration of a unipolar converter with improved switching performance suitable for switched-reluctance motor supply is presented. The switched-reluctance motor operation principle is presented, and its ideal characteristics are considered. The proposed converter is described, and its operation is analyzed. The converter characteristics are studied with the aid of computer simulation. Current control of the proposed converter is considered. A prototype converter has been built to verify the analysis results and to validate the simulation. The design procedure is presented, and experimental results which confirm the analysis are given and discussed.

Le-Huy, Hoang; Viarouge, Philippe; Francoeur, Bruno

1990-10-01

403

Relationship Among Efficiency and Output Power of Heat Energy Converters  

E-print Network

Relationship among efficiency and output power of heat-electric energy converters as well as of any converters for transforming of heat energy into any other kind of energy is considered. It is shown, that the parameter efficiency does not determine univocally the output power of a converter. It is proposed to use another parameter for determination of working ability of heat energy converters. It is shown, that high output power can not be achieved by any kind of Stirling-type converters in spite of their high efficiency.

Alexander Luchinskiy

2004-09-02

404

Trans-Linked Single Phase Interleaved PFC Converter  

NASA Astrophysics Data System (ADS)

The novel trans-linked single phase interleaved PFC converter suitable for the plug-in hybrid electric vehicle is proposed in this paper. The proposed trans-linked PFC converter can achieve the miniaturized performance for its scale and weight. As compared with the conventional single phase PFC converter, the core size and the value of the smoothing capacitor in the proposed trans-linked PFC converter is less than 1/2 that in the conventional one. Though the miniaturized performance, the proposed trans-linked PFC converter can be operated under the control system of the conventional interleaved single phase PFC converter. The operation characteristics and performances of the proposed trans-linked PFC converter is evaluated and discussed with experimental results.

Yamamoto, Masayoshi; Horii, Hiroyuki

405

The effect of raffinose and methionine on frozen/thawed Angora buck (Capra hircus ancryrensis) semen quality, lipid peroxidation and antioxidant enzyme activities.  

PubMed

The aim of the present study was to determine the effects of different doses of raffinose and methionine on post-thawed semen quality, lipid peroxidation and antioxidant enzyme activities of Angora buck (Capra hircus ancryrensis) sperm following cryopreservation. Ejaculates collected from three Angora bucks were evaluated and pooled at 37 degrees C. Semen samples, which were diluted with a Tris-based extender containing the additives raffinose (2.5, 5, 10mM) and methionine (2.5, 5, 10mM) and an extender containing no antioxidants (control), were cooled to 5 degrees C and frozen in 0.25 ml French straws. Frozen straws were thawed individually at 37 degrees C for 20s in a water bath for evaluation. The freezing extender supplemented with 2.5 and 5mM methionine led to higher percentages of CASA motility (63.6+/-7.0; 63.4+/-3.1%, respectively), in comparison to the controls (P<0.01) following the freeze-thawing process. The addition of antioxidants did not provide any significant effect on the percentages of post-thaw subjective and CASA progressive motilities as well as sperm motion characteristics (VSL and VCL), compared to the control groups (P>0.05). The freezing extender with raffinose (5 and 10mM) and methionine at three different doses (2.5, 5 and 10mM) led to lower percentages of acrosome abnormalities, in comparison to the controls (P<0.001). In the comet test, raffinose (5 and 10mM) and methionine (10mM) gave scores lower than those of the controls, and thereby reduced DNA damage (P<0.05). Malondialdehyde formation was found to be lower (1.8+/-0.1 nmol/L) in the group of 5mM raffinose, compared to the controls following the freeze-thawing process (P<0.01). The additives did not show any effectiveness on the maintenance of SOD, GSH-PX and GSH activities, when compared to the controls (P>0.05). In conclusion, methionine and raffinose play a cryoprotective role against sperm CASA motility, acrosome abnormality and DNA damage. Raffinose 5mM exhibited antioxidative properties, decreasing MDA levels. Further studies are required to obtain more concrete results on the characterization of microscopic parameters and antioxidant activities in cryopreserved goat sperm with different additives. PMID:20515679

Tuncer, Pürhan Barbaros; Bucak, Mustafa Numan; Sariözkan, Serpil; Sakin, Fatih; Yeni, Deniz; Ci?erci, Ibrahim Hakki; Ate??ahin, Ahmet; Avdatek, Fatih; Gündo?an, Mustafa; Büyükleblebici, Olga

2010-08-01

406

Convertibility verification and converter synthesis: two faces of the same coin  

Microsoft Academic Search

An essential problem in component-based design is how to compose components designed in isolation. Several approaches have been proposed for specifying component interfaces that capture behavioral aspects such as interaction protocols, and for verifying interface compatibility. Likewise, several approaches have been developed for synthesizing converters between incompatible protocols. In this paper, we introduce the notion of adaptability as the property

Roberto Passerone; Luca de Alfaro; Thomas A. Henzinger; Alberto L. Sangiovanni-Vincentelli

2002-01-01

407

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

Microsoft Academic Search

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

Ika Darnhofer; Walter Schneeberger; Bernhard Freyer

2005-01-01

408

Angiotensin converting enzyme inhibition and the kidney  

NASA Technical Reports Server (NTRS)

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

Hollenberg, N. K.

1988-01-01

409

DC-to-DC switching converter  

NASA Technical Reports Server (NTRS)

A dc-to-dc converter having nonpulsating input and output current uses two inductances, one in series with the input source, the other in series with the output load. An electrical energy transferring device with storage, namely storage capacitance, is used with suitable switching means between the inductances to DC level conversion. For isolation between the source and load, the capacitance may be divided into two capacitors coupled by a transformer, and for reducing ripple, the inductances may be coupled. With proper design of the coupling between the inductances, the current ripple can be reduced to zero at either the input or the output, or the reduction achievable in that way may be divided between the input and output.

Cuk, Slobodan M. (Inventor); Middlebrook, Robert D. (Inventor)

1980-01-01

410

Modular Power Converters for PV Applications  

SciTech Connect

This report describes technical opportunities to serve as parts of a technological roadmap for Shoals Technologies Group in power electronics for PV applications. There are many different power converter circuits that can be used for solar inverter applications. The present applications do not take advantage of the potential for using common modules. We envision that the development of a power electronics module could enable higher reliability by being durable and flexible. Modules would have fault current limiting features and detection circuits such that they can limit the current through the module from external faults and can identify and isolate internal faults such that the remaining modules can continue to operate with only minimal disturbance to the utility or customer. Development of a reliable, efficient, low-cost, power electronics module will be a key enabling technology for harnessing more power from solar panels and enable plug and play operation. Power electronics for computer power supplies, communication equipment, and transportation have all targeted reliability and modularity as key requirements and have begun concerted efforts to replace monolithic components with collections of common smart modules. This is happening on several levels including (1) device level with intelligent control, (2) functional module level, and (3) system module. This same effort is needed in power electronics for solar applications. Development of modular units will result in standard power electronic converters that will have a lower installed and operating cost for the overall system. These units will lead to increased adaptability and flexibility of solar inverters. Incorporating autonomous fault current limiting and reconfiguration capabilities into the modules and having redundant modules will lead to a durable converter that can withstand the rigors of solar power generation for more than 30 years. Our vision for the technology roadmap is that there is no need for detailed design of new power converters for each new application or installation. One set of modules and controllers can be pre-developed and the only design question would be how many modules need to be in series or parallel for the specific power requirement. Then, a designer can put the modules together and add the intelligent reconfigurable controller. The controller determines how many modules are connected, but it might also ask for user input for the specific application during setup. The modules include protection against faults and can reset it, if necessary. In case of a power device failure, the controller reconfigures itself to continue limited operation until repair which might be as simple as taking the faulty module out and inserting a new module. The result is cost savings in design, maintenance, repair, and a grid that is more reliable and available. This concept would be a perfect fit for the recently announced funding opportunity announcement (DE-FOA-0000653) on Plug and Play Photovoltaics.

Ozpineci, Burak [ORNL; Tolbert, Leon M [ORNL

2012-05-01

411

Combination acoustical muffler and exhaust converter  

SciTech Connect

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

Nitz, A.E.

1982-11-30

412

Radiant energy to electric energy converter  

NASA Technical Reports Server (NTRS)

Radiant energy is converted into electric energy by irradiating a capacitor including an ionic dielectric. The dielectric is a sintered crystal superionic conductor, e.g., lanthanum trifluoride, lanthanum trichloride, or silver bromide, so that a multiplicity of crystallites exist between electrodes of the capacitor. The radiant energy cyclically irradiates the dielectric so that the dielectric exhibits a cyclic photocapacitive like effect. Adjacent crystallites have abutting surfaces that enable the crystallites to effectively form a multiplicity of series capacitor elements between the electrodes. Each of the capacitor elements has a dipole layer only on or near its surface. The capacitor is initially charged to a voltage just below the dielectric breakdown voltage by connecting it across a DC source causing a current to flow through a charging resistor to the dielectric. The device can be utilized as a radiant energy detector or as a solar energy cell.

Sher, Arden (Inventor)

1980-01-01

413

Static Frequency Converter System Installed and Tested  

NASA Technical Reports Server (NTRS)

A new Static Frequency Converter (SFC) system has been installed and tested at the NASA Glenn Research Center s Central Air Equipment Building to provide consistent, reduced motor start times and improved reliability for the building s 14 large exhausters and compressors. The operational start times have been consistent around 2 min, 20 s per machine. This is at least a 3-min improvement (per machine) over the old variable-frequency motor generator sets. The SFC was designed and built by Asea Brown Boveri (ABB) and installed by Encompass Design Group (EDG) as part of a Construction of Facilities project managed by Glenn (Robert Scheidegger, project manager). The authors designed the Central Process Distributed Control Systems interface and control between the programmable logic controller, solid-state exciter, and switchgear, which was constructed by Gilcrest Electric.

Brown, Donald P.; Sadhukhan, Debashis

2003-01-01

414

Converting energy from fusion into useful forms  

E-print Network

If fusion power reactors are to be feasible, it will still be necessary to convert the energy of the nuclear reaction into usable form. The heat produced will be removed from the reactor core by a primary coolant, which might be water, helium, molten lithium-lead, molten lithium-containing salt, or CO2. The heat could then be transferred to a conventional Rankine cycle or Brayton (gas turbine) cycle. Alternatively it could be used for thermochemical processes such as producing hydrogen or other transport fuels. Fusion presents new problems because of the high energy neutrons released. These affect the selection of materials and the operating temperature, ultimately determining the choice of coolant and working cycle. The limited temperature ranges allowed by present day irradiated structural materials, combined with the large internal power demand of the plant, will limit the overall thermal efficiency. The operating conditions of the fusion power source, the materials, coolant, and energy conversion system w...

Kovari, M; Jenkins, I; Kiely, C

2014-01-01

415

Digital readout for image converter cameras  

NASA Astrophysics Data System (ADS)

There is an increasing need for fast and reliable analysis of recorded sequences from image converter cameras so that experimental information can be readily evaluated without recourse to more time consuming photographic procedures. A digital readout system has been developed using a randomly triggerable high resolution CCD camera, the output of which is suitable for use with IBM AT compatible PC. Within half a second from receipt of trigger pulse, the frame reformatter displays the image and transfer to storage media can be readily achieved via the PC and dedicated software. Two software programmes offer different levels of image manipulation which includes enhancement routines and parameter calculations with accuracy down to pixel levels. Hard copy prints can be acquired using a specially adapted Polaroid printer, outputs for laser and video printer extend the overall versatility of the system.

Honour, Joseph

1991-04-01

416

Mining disease state converters for medical intervention of diseases.  

PubMed

In applications such as gene therapy and drug design, a key goal is to convert the disease state of diseased objects from an undesirable state into a desirable one. Such conversions may be achieved by changing the values of some attributes of the objects. For example, in gene therapy one may convert cancerous cells to normal ones by changing some genes' expression level from low to high or from high to low. In this paper, we define the disease state conversion problem as the discovery of disease state converters; a disease state converter is a small set of attribute value changes that may change an object's disease state from undesirable into desirable. We consider two variants of this problem: personalized disease state converter mining mines disease state converters for a given individual patient with a given disease, and universal disease state converter mining mines disease state converters for all samples with a given disease. We propose a DSCMiner algorithm to discover small and highly effective disease state converters. Since real-life medical experiments on living diseased instances are expensive and time consuming, we use classifiers trained from the datasets of given diseases to evaluate the quality of discovered converter sets. The effectiveness of a disease state converter is measured by the percentage of objects that are successfully converted from undesirable state into desirable state as deemed by state-of-the-art classifiers. We use experiments to evaluate the effectiveness of our algorithm and to show its effectiveness. We also discuss possible research directions for extensions and improvements. We note that the disease state conversion problem also has applications in customer retention, criminal rehabilitation, and company turn-around, where the goal is to convert class membership of objects whose class is an undesirable class. PMID:20183875

Dong, Guozhu; Duan, Lei; Tang, Changjie

2010-02-01

417

Changes in the quality of meat from roe deer (Capreolus capreolus L.) bucks during cold storage under vacuum and modified atmosphere.  

PubMed

This paper analyses changes in the quality of meat (M. longissimus dorsi) of roe deer bucks during 21 days of cold storage (2 degrees C) under vacuum and modified atmosphere (MA) conditions (40% CO2/60% N2 and 60% CO2/40% N2). After 21 days of storage, meat packaged in a MA with 40% CO2 had higher (P < or = 0.05) L*, a*, b* and C* values in comparison with meat stored under vacuum and MA with 60% CO2. The mean pH and TBARS values of meat packaged under vacuum and a MA with 40% CO2 were increasing for the first 7 days of storage, and then they decreased (P < or = 0.05). Following storage, the colour of meat became lighter (L*) and more yellow (b*). The meat stored under vacuum was characterised by increased (P < or = 0.05) cooking loss. During meat storage, a significant increase (P < or = 0.05) in total microbial counts and psychrotrophic bacteria was observed. PMID:21957742

Daszkiewicz, T; Kondratowicz, J; Koba-Kowalczyk, M

2011-01-01

418

Identification of water-bearing fractures by the use of geophysical logs, May to July 1998, former Naval Air Warfare Center, Bucks County, Pennsylvania  

USGS Publications Warehouse

Between May and July 1998, 10 monitor wells were drilled near the site of the former Naval Air Warfare Center (NAWC), Warminster, Bucks County, Pa., to monitor water levels and sample ground water in shallow and intermediate water-bearing fractures. The sampling will determine the horizontal and vertical distribution of contaminated ground water migrating from known or suspected sources. Three boreholes were drilled on the property at 960 Jacksonville Road, at the northwestern side of NAWC, along strike from Area A; seven boreholes were drilled in Area B in the southeastern corner of NAWC. Depths range from 40.5 to 150 feet below land surface. Borehole geophysical logging and video surveys were used to identify water-bearing fractures so that appropriate intervals could be screened in each monitor well. Geophysical logs were obtained at the 10 monitor wells. Video surveys were obtained at three monitor wells in the southeastern corner of the NAWC property. Caliper logs and video surveys were used to locate fractures. Inflections on fluid-temperature and fluid-resistivity logs were used to locate possible water-bearing fractures. Heatpulse-flowmeter measurements verified these locations. Natural-gamma logs provided information on stratigraphy. After interpretation of geophysical logs, video surveys, and driller?s logs, all wells were screened such that water-level fluctuations could be monitored and water samples collected from discrete water-bearing fractures in each monitor well.

Conger, Randall W.; Bird, Philip H.

1999-01-01

419

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

SciTech Connect

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

None

2012-02-09

420

Active-clamp ZVS two-switch flyback converter  

Microsoft Academic Search

This paper introduces a zero voltage switching (ZVS) two-switch flyback pulse-width modulated (PWM) DC-DC converter along with the principle of circuit operation and steady-state analysis. The proposed converter topology is the result of incorporating an auxiliary circuit in place of the clamping diodes on the primary side of the conventional hard- switching two-switch flyback converter, resulting in a soft- switching

Dakshina Murthy-Bellur; Marian K. Kazimierczuk

2011-01-01

421

10MW GTO converter for battery peaking service  

Microsoft Academic Search

A bidirectional 18-pulse voltage-source converter utilizing gate-turnoff thyristors (GTOs) is described. The converter, which is rated 10 MVA, was placed in service in early 1988 to connect an energy storage battery to a utility grid. The converter is rated and controlled to operate in all four quadrants (discharge, charge, leading VAr, or lagging VAr) at the full 10 MVA rating.

L. H. Walker

1990-01-01

422

High performance coupled-inductor DC-DC converters  

Microsoft Academic Search

Many emerging applications call for high-efficiency, high-step-up DC-DC converters. Basic DC-DC topologies encounter extreme duty ratio and severe rectifier reverse-recovery problems. Cascade DC-DC converters can meet the requirements with the drawbacks of extra complexity and higher cost. Coupled-inductor DC-DC converters can provide high step-up voltage gain without the penalty of extreme duty ratio, but the stress and the loss related

Qun Zhao; Fred C. Lee

2003-01-01

423

Determinants of Angiotensin II Generation During Converting Enzyme Inhibition  

Microsoft Academic Search

The reaction of the renin-angiotensin system to acute angiotensin converting enzyme inhibition was investigated in a single-blind, crossover study in nine normal volunteers receiving two out of three regimens in random order the new converting enzyme inhibitor benazepril (20 mg once or 5 mg four times at 6-hour intervals) or enalapril (20 mg). Plasma converting enzyme activity, drug levels, angiotensin

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

2010-01-01

424

A high voltage power converter for space astronomy applications  

NASA Technical Reports Server (NTRS)

A dc-dc low-power, high-voltage converter for use in space is described which furnishes a commandable, low-noise dc output in the range of 0 to -7500 V. The converter is suitable for biasing of detectors commonly employed in space astronomy, microchannel plates, photomultipliers, and gas discharge detectors. The converter's reliability has been demonstrated by accelerated life testing under thermal vacuum. The electrical and mechanical design, packaging, layout and fabrication techniques, and tests employed are described.

Ray, David C.; Lampton, Michael L.

1988-01-01

425

Thermionic converter output as a function of collector temperature  

NASA Technical Reports Server (NTRS)

Surprisingly few data are available on the variation of thermionic converter output with collector temperature. In this study the output power density has been measured as a function of collector temperature (at a fixed emitter temperature of 1650 K) for six converters with different electrode combinations. Collector temperatures ranged from 750 to 1100 K. For collector temperatures below 900 K, converters built with sublimed molybdenum oxide collectors gave the best performance.

Stark, G.; Saunders, M.; Lieb, D.

1980-01-01

426

Asynchronous Sigma-Delta Analog-to-Digital Converter  

Microsoft Academic Search

The paper describes Asynchronous Sigma-Delta Modulator Analog-to-Digital Converter (ASD-ADC) built around the first order ASD modulator. Asynchronous sigma-delta modulator performs asynchronous amplitude-to-time conversion creating 1-bit output sequence which is further sampled by the Time-to-Digital Converter (TDC) and converted into the time-discrete synchronous m-bit words, suitable for further digital signal processing. Proposed ASD-ADC architecture, simulation of its MATLAB® model and evaluation

T. Matic?; T. S?vedek; D. Vinko

2010-01-01

427

Design and technology of compact high-power converters  

Microsoft Academic Search

New material technologies such as silicon carbide (SiC) are promising in the development of compact high-power converters for next-generation power electronics applications. This paper presents an optimized converter design approach that takes into consideration nonlinear interactions among various converter components, source and load. It is shown that with the development of high-temperature, high-power SiC power module technology, magnetic components and

Krishna Shenai; Philip G. Neudeck; G. Schwarze

2000-01-01

428

Power Converters Maximize Outputs Of Solar Cell Strings  

NASA Technical Reports Server (NTRS)

Microprocessor-controlled dc-to-dc power converters devised to maximize power transferred from solar photovoltaic strings to storage batteries and other electrical loads. Converters help in utilizing large solar photovoltaic arrays most effectively with respect to cost, size, and weight. Main points of invention are: single controller used to control and optimize any number of "dumb" tracker units and strings independently; power maximized out of converters; and controller in system is microprocessor.

Frederick, Martin E.; Jermakian, Joel B.

1993-01-01

429

Robust controller design for a parallel resonant converter using ?-synthesis  

Microsoft Academic Search

DC-to-DC resonant power converters have been the subject of much attention recently. These power converters have the potential to provide high-performance conversion without some of the problems associated with classical pulse-width modulation (PWM)-based converters, thus allowing for smaller, lighter power supplies. However, in order to achieve this, a suitable control circuit, capable of maintaining the desired output voltage under different

Juanyu Bu; Mario Sznaier; Zi-Qin Wang; I. Baterseh

1997-01-01

430

Voltage tolerance testing of three-phase voltage source converters  

Microsoft Academic Search

This paper proposes a protocol for testing the immunity of three-phase self-commutated converters to voltage dips. An overview of voltage dips due to short circuits and earth faults that may affect a converter is given and their effect on the converter is demonstrated through simulation. Results confirm that the existing standard protocol given in IEC 61000-4-11 is not complete. An

Ambra Sannino; Math H. J. Bollen; Jan Svensson

2005-01-01

431

Background Calibration of Gain Errors in A\\/D Converters  

Microsoft Academic Search

This paper describes a method of calibrating gain errors in each channel of Hadamard modulated parallel delta-sigma (???) converters. The ??? converters extend traditionally bandwidth-limited ?? modulators to applications such as wireless communications that require high-resolution wide-bandwidth converters. The focus of this paper is on the development and convergence of an adaptive calibration algorithm. A hardware implementation that verifies this

A. Delic?-Ibukic?; D. M. Hummels

2010-01-01

432

A Novel Converter System for Fuel Cell Distributed Energy Generation  

Microsoft Academic Search

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

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

2005-01-01

433

Pseudo-resonant full bridge DC\\/DC converter  

Microsoft Academic Search

A DC-DC power converter topology that combines the ease of control and wide range of conventional DC-DC converters, with low switching losses, low dv\\/dt and low electromagnetic interference that is typical of zero voltage switched resonant converters is proposed. Consequently, the ratings of these components are substantially lower than for similarly rated resonant topologies. While resonant elements are used to

O. D. Patterson; D. M. Divan

1991-01-01

434

High-power converters for space applications  

NASA Technical Reports Server (NTRS)

Phase 1 was a concept definition effort to extend space-type dc/dc converter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.

Park, J. N.; Cooper, Randy

1991-01-01

435

Advanced thermionic converter developments with microwave external pumping  

NASA Technical Reports Server (NTRS)

This work reports ion generation in a cesium thermionic converter as part of advanced-model thermionic converter development research. A microwave with frequency in the range between 1-2 GHz is used to externally pump a thermionic converter as part of our effort in the verification of Lam's theory. It is found that the motive peak as predicted in the theory disappears whenever microwave power is used to excite the cesium plasma of the converter. The electron temperature is effectively heated by the microwave and the experimental data agrees with theory in the low-power output region.

Chiu, H. S.; Shaw, D. T.; Manikopulos, C. N.; Lee, C. H.

1977-01-01

436

Angiotensin Converting Enzyme Activity in Alopecia Areata  

PubMed Central

Background. Alopecia areata (AA) is a chronic inflammatory disease of the hair follicle. The exact pathogenesis of AA remains unknown, although recent studies support a T-cell mediated autoimmune process. On the other hand, some studies have proposed that the renin-angiotensin-aldosterone system (RAAS) may play a role in autoimmunity. Therefore, we assessed serum activity of angiotensin converting enzyme (ACE), a component of this system, in AA. Methods. ACE activity was measured in the sera of 19 patients with AA and 16 healthy control subjects. In addition, the relationship between severity and duration of the disease and ACE activity was evaluated. Results. Serum ACE activity was higher in the patient group (55.81?U/L) compared to the control group (46.41?U/L), but the difference was not statistically significant (P = 0.085). Also, there was no correlation between ACE activity and severity (P = 0.13) and duration of disease (P = 0.25) in the patient group. Conclusion. The increased serum ACE activity found in this study may demonstrate local involvement of the RAAS in the pathogenesis of AA. Assessment of ACE in a study with a larger sample size as well as in tissue samples is recommended in order to further evaluate the possible role of RAAS in AA. PMID:25349723

Namazi, Mohammad Reza; Handjani, Farhad; Eftekhar, Ebrahim; Kalafi, Amir

2014-01-01

437

Converting sensitive waste into cleaner energy  

SciTech Connect

The destruction of sensitive unclassified information (SUI) has always been expensive due to the need for special controls to ensure its protection from disclosure to unauthorized persons. The sensitive documents were shredded, buried at the landfill, or sent to a recycling company. The Department of Energy (DOE) Idaho National Engineering and Environmental Laboratory (INEEL), operated by Lockheed Martin Idaho Technologies Company (LMITCO), has created an innovative method to dispose of its sensitive unclassified paper waste which has security, economic, and environmental benefits. A new cubing facility at the INEEL converts office and industrial waste into compact cubes which are then combined with coal and burned as a source of heat and process steam to run the Idaho Chemical Processing Plant (ICPP) facility. The process-engineered fuel, consisting of 25% cubes and 75% coal, bums cleaner than coal with lower emissions of sulfur dioxide and nitrogen oxides. The alternative fuel also reduces fuel costs, eliminates paying a recycling company, reduces the expense of landfill disposal, increases the life of the landfill, and provides energy to operate a large facility. The Operations Security (OPSEC) team capitalized on this waste to energy technology by recommending that the large quantities of sensitive information (documents) generated at the INEEL be disposed of in this manner. In addition to the economic and environmental benefits, this disposal method minimizes the vulnerabilities of SUI from disclosure to unauthorized personnel. The {open_quotes}cuber{close_quotes} technology has potential application in government and industry for protection of SUI.

Schriner, D.; Skinner, R.

1997-10-01

438

Effective plasmonic mode-size converter.  

PubMed

Plasmonic mode-size converters (PMSCs) for long-range surface plasmon polaritons (LR-SPPs) at the wavelength of 1.55 ?m are presented. The PMSC is composed of an insulator-metal-insulator waveguide (IMI-W), a laterally tapered insulator-metal-insulator-metal-insulator waveguide (LT-IMIMI-W), and an IMIMI-W in series. The mode-intensity sizes of the LR-SPPs for the IMI-W and the IMIMI-W were not only calculated using a finite element method but were also experimentally measured. The propagation losses of the IMI-W and the IMIMI-W as well as the coupling losses between them were analyzed by the cut-back method to investigate the effect of LT-IMIMI-Ws. By using the PMSC with a ~27 ° angled LT-IMIMI-W, the coupling loss between a polarization-maintaining fiber and a 3 ?m-wide IMIMI-W was reduced by ~3.4 dB. Moreover, the resulting mode-intensity in the output of the PMSC was squeezed to ~35% of the mode-intensity in the input IMI-W. The PMSC may be potentially useful for bridging micro- to nano-plasmonic integrated circuits. PMID:22109009

Park, Hae-Ryeong; Park, Jong-Moon; Kim, Min-su; Ju, Jung Jin; Son, Jung-Han; Lee, Myung-Hyun

2011-10-24

439

Novel Modulation Method for Multidirectional Matrix Converter  

PubMed Central

This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation. PMID:25298969

Misron, Norhisam; Aris, Ishak Bin; Yamada, Hiroaki

2014-01-01

440

Active clamp boost converter with switched capacitor and coupled inductor  

Microsoft Academic Search

A high step-up converter with a coupled inductor and a switched capacitor is proposed in this paper. By using the coupled inductor, the voltage gain of the converter is extended and the voltage stress of the main switch is decreased to reduce the conduction losses. Moreover, the reverse-recovery problem of the output diode is alleviated by the leakage inductance. By

Yi Zhao; Wuhua Li; Bo Yang; Xiangning He

2010-01-01

441

Analysis, design and implementation of an active clamp flyback converter  

Microsoft Academic Search

This paper presents the detailed circuit operation, mathematical analysis, and design example of the active clamp flyback converter. The auxiliary switch and clamp capacitor are used in the flyback converter to recycle the energy stored in the transformer leakage in order to minimize the spike voltage at the transformer primary side. Therefore the voltage stress of main switch can be

Bor-Ren Lin; Huann-Keng Chiang; Kao-Cheng Chen; D. Wang

2005-01-01

442

Dynamic current distribution controls of a parallel connected converter system  

Microsoft Academic Search

Based on the central-limit control algorithm for the parallel connected converter system, two improved dynamic current distribution control methods are introduced: the programmable current distribution control (PCDC) and the maximum current limit control (MCLC). In PCDC, the ratio of the output current of each converter to the total output current can be programmed according to the desired application objective while

C. Q. Lee; K. Siri; T.-F. Wu

1991-01-01

443

Design of de-ionised water cooling of power converters  

Microsoft Academic Search

Power electronics converters need cooling devices. High thermal performances allows decrease of converter volume and cost, and have a major impact on long-term reliability. Semiconductors encapsulation structure have to combine two opposite requirements, namely low thermal resistance and electrical insulation capabilities. Among numbers of designs (ceramics, diamond, polymers etc.), dielectric fluid cooling has been used for high voltage applications (oil,

E. Ramchy; B. Malinowska; M. Cassir

1998-01-01

444

Technologies for Designing Dependable A\\/D Converters  

Microsoft Academic Search

Although considerable research has been conducted on fault tolerance at the system level and results in system level fault tolerance have been applied to some actual systems, only a few research reports on fault tolerant A\\/D converters have appeared in the literature. Since A\\/D converters are extensively used in many actual systems and have important roles as input devices for

Kyoya Kawamura; Takashji Matsubara; Yoshiaki Koga

1996-01-01

445

Harmonic current reduction of a six-pulse thyristor converter  

Microsoft Academic Search

This paper presents a line injection technique in order to reduce line current harmonics generated by AC\\/DC three-phase thyristor converters. The principle of this technique is to modify the current waveforms on the DC side windings of the converter transformer by injecting every harmonic components of the rectified current with an opposite phase. The proposed technique consists of an interconnection

B. M. Saied; H. I. Zynal

2007-01-01

446

Coupled Dual Interleaved Flyback Converter for High Input Voltage Application  

E-print Network

is utilized for Push-Pull Forward circuit with coupled-inductor current doubler circuit [3,4]. A single EI-down transformer and the output filtering inductor. As well as reducing the overall size of the converter, coupledCoupled Dual Interleaved Flyback Converter for High Input Voltage Application Ting Qian, Brad

Lehman, Brad

447

A BEHAVIORAL AVERAGE MODEL OF SEPIC CONVERTERS WITH COUPLED INDUCTORS  

E-print Network

1 A BEHAVIORAL AVERAGE MODEL OF SEPIC CONVERTERS WITH COUPLED INDUCTORS D. Adar, G. Rahav and S@bguee.bgu.ac.il Abstract An average model of SEPIC converters with coupled inductors was developed and verified against state (DC), large signal (Transient) and small signal (AC) analyses. The inductors coupling coefficient

448

Power electronic converter EMC analysis through state variable approach techniques  

Microsoft Academic Search

A technique based on the state vector approach and a simple switch device model is proposed for electromagnetic compatibility (EMC) analysis in converter design. The conducted noise spectrum is straightforward computed in the frequency domain for hard switching converters with alternating or direct current input sources. The results are compared with PSpice time-domain simulations mixed with the fast Fourier transform,

Popescu Radu Mugur; James Roudet; Jean-Christophe Crebier

2001-01-01

449

Prototype testing of the wave energy converter wave dragon  

Microsoft Academic Search

The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power.In the period from 1998 to 2001 extensive wave tank testing on a scale model

Jens Peter Kofoed; Peter Frigaard; Erik Friis-Madsen; Hans Chr. Sørensen

2006-01-01

450

Dynamic modeling and controller design of flyback converter  

Microsoft Academic Search

The accurate dynamic modeling and quantitative controller design for an isolated converter with optocoupler isolation in its feedback loop are considered to be difficult issues, since the transfer characteristics of some blocks are highly nonlinear and difficult to be modeled analytically. First a current-mode controlled flyback converter with an optically isolated feedback path is designed. Then the equivalent control system

T. H. Chen; W. L. Lin; C. M. Liaw

1999-01-01

451

Converting enzyme inhibition and progressive glomerulosclerosis in the rat  

Microsoft Academic Search

Converting enzyme inhibition and progressive glomerulosclerosis in the rat. The effect of converting enzyme inhibition (CEI) by captopril (CAP, 500 mg\\/liter drinking water) on the development and progression of glomerulosclerosis (GS) was studied in six groups of male unine-phrectomized (UN) Wistar rats. In group A, treated with CAP for four to five weeks after UN, a reduction in systolic blood

Joke J B Beukers; Annemieke van der Wal; Philip J Hoedemaeker; Jan J Weening

1987-01-01

452

The Matrix Converter Drive Performance Under Abnormal Input Voltage Conditions  

E-print Network

-8530, Japan e-mail:kang@yaskawa.co.jp Abstract- The matrix converter is a direct frequency conversion device laboratory experiments. I. INTRODUCTION The matrix converter (MC) is a direct frequency conversion device that generates variable magnitude variable frequency output voltage from the ac utility line. It has high power

Hava, Ahmet

453

On the dynamics of a novel ocean wave energy converter  

Microsoft Academic Search

Buoy-type ocean wave energy converters are designed to exhibit resonant responses when subject to excitation by ocean waves. A novel excitation scheme is proposed which has the potential to improve the energy harvesting capabilities of these converters. The scheme uses the incident waves to modulate the mass of the device in a manner which amplifies its resonant response. To illustrate

B. Orazov; O. M. O’Reilly; Ö. Savas

2010-01-01

454

MAGNET POWER CONVERTERS FOR THE NEW ELETTRA FULL ENERGY INJECTOR  

Microsoft Academic Search

A large number of power converters has been required to supply the coils and the magnets of the four sub- structures of the new Elettra full energy injector. The Linac and the two transfer lines require highly stabilized DC power converters, while the Booster has to be operated at 3 Hz supplying the magnets with sinusoidal current waveforms. The extraction

Roberto Visintini; Giuseppe Cautero; Marco Cautero; Michele Svandrlik; Maurizio Zaccaria

455

Emissions reductions using hydrogen from plasmatron fuel converters  

Microsoft Academic Search

Improvements in internal combustion engine and aftertreatment technologies are needed to meet future environmental quality goals. Systems using recently developed compact plasmatron fuel converters in conjunction with state-of-the-art engines and aftertreatment catalysts could provide new opportunities for obtaining substantial emissions reductions. Plasmatron fuel converters provide a rapid response, compact means to transform a wide range of hydrocarbon fuels (including gasoline,

L Bromberg; D. R Cohn; A Rabinovich; J Heywood

2001-01-01

456

Pulse width modulation scheme for the Modular Multilevel Converter  

Microsoft Academic Search

The Modular Multilevel Converter (M2C) is an emerging and highly attractive multilevel converter topology for medium and high voltage applications. In this paper, a new pulse width modulation (PWM) scheme will be derived. For this pulse width modulation scheme, characteristic simulated waveforms are described and analyzed.

Steffen Rohner; Steffen Bernet; Marc Hiller; Rainer Sommer

2009-01-01

457

Post?conversion experiences of native British converts to Islam  

Microsoft Academic Search

Research has been carried out on native British converts to Islam. It was based on formal interviews with 70 converts to Islam, 50 males and 20 females. Interviews were done in various parts of England. The sample consïsted of 66 English, 3 Irish, and 1 Welsh. Fifty?one had been Anglicans, 12 Catholics, 3 Methodists, and 4 Jews. The research was

Ali köse

1994-01-01

458

Thermally Isolated MEMS Thermo Converter for RF Power Sensor  

Microsoft Academic Search

This report discusses the design of Thermo-mechanical converter that creates heart of the RF power sensor microsystem. The conception of absorbed power measurement is based on thermal conversion, where absorbed RF power is transformed into thermal power, inside a thermally isolated system. Micromechanical Thermal Converter (MTC) spatial temperature dependences, thermal time constant and power to temperature characteristics are calculated from

JIRI JAKOVE NKO; MIROSLAV HUSAK; TIBOR LALINSKY

459

Symbolic analysis methods for averaged modeling of switching power converters  

Microsoft Academic Search

Symbolic analysis methods for the averaged modeling of switching power converters are presented in this paper. A general averaging method suitable for computer-aided modeling is discussed first. Then, a symbolic analysis package that uses this averaging method to automatically generate an analytical averaged model for a switching power converter is described. The package is implemented using the computer algebra system

Jian Sun; Horst Grotstollen

1997-01-01

460

"Black Box" EMC model for Power Electronics Converter Mikael Foissac  

E-print Network

"Black Box" EMC model for Power Electronics Converter Mikael Foissac Grenoble Electrical. Even if this allows a better power management, power electronics generates high EMI level, which must many power electronics converters is too complex to reach a sufficient accuracy in the high frequency

Paris-Sud XI, Université de

461

Drive System for Traction Applications Using 81-Level Converter  

E-print Network

Concepción, CHILE jdixon@ing.puc.cl lmoran@die.udec.cl Abstract--A multilevel inverter for traction drive are compared with conventional PWM inverters working at a switching frequency of 10 kHz. All the load-phase inverters or for dual converters. These converters are able to produce three levels of voltage in the load

Catholic University of Chile (Universidad Católica de Chile)

462

Multiple Input Converters for Fuel Cells Burak Ozpineci1  

E-print Network

-dc converter and a cascaded multilevel inverter are used to integrate several fuel cell modules. When recently-2100 Abstract-- Multilevel converters have been used previously to integrate several fuel cell modules. These modules can be integrated in different configurations to yield the necessary power. The multilevel

Tolbert, Leon M.

463

Wavelength Converters in Dynamically-Reconfigurable WDM Networks  

Microsoft Academic Search

In simple wavelength-division multiplexed (WDM) networks, a connection must be established along a route using a common wavelength on all of the links along the route. This constraint may be removed by the introduction of wavelength converters, which are devices which take the data modulated on an input wavelength and transfer it to a different output wavelength. Wavelength converters thus

Jennifer M. Yates; Michael P. Rumsewicz; Jonathan P. R. Lacey

1999-01-01

464

CONVERTER FOILS FOR THE SPECTROSCOPY OF $gamma$ EMITTERS  

Microsoft Academic Search

The effect of atomic number and thickness of converters during gamma ; spectroscopy with a magnetic short-line spectrometer on the intensity and ; resolution of photolines is reported. Lead and uranium foils were used as ; converters, and their preparation is described. The measurements were carried ; out at three gamma energies. Optimum values for the thickness of the foils

K. Baumann; J. Schintlmeister; R. Weibrecht

1961-01-01

465

Animal Model Mice with Cardiac-Restricted Angiotensin-Converting  

E-print Network

Animal Model Mice with Cardiac-Restricted Angiotensin-Converting Enzyme (ACE) Have Atrial created a mouse model with 100-fold nor- mal cardiac angiotensin-converting enzyme (ACE), but no ACE morphological changes, cardiac arrhythmia, and sudden death. (Am J Pathol 2004, 165:1019­1032) The renin

Capecchi, Mario R.

466

A voltage resonant single ended converter with auxiliary switch  

Microsoft Academic Search

This paper describes a new single-ended voltage resonance power converter without changing the period of a main switch S1 and with changing the conduction period. The power converter is composed of a parallel LC-resonance circuit and an auxiliary switch S2. New topologies for the auxiliary switch S2 is derived from a half-cycle delay concept

Toshihiro Onodera; Toshiba Komukai

1998-01-01

467

Power Control for Pulse-Density Modulation Resonant Converters  

Microsoft Academic Search

PDM can be used to drive resonant power converters and is a good alternative to pulse width modulation (PWM). Its main advantages are its simplicity and that it allows power device's zero-current (or voltage) switching (ZCS or ZVS), while performing load power regulation. This technique is suitable for designing power converters that show an overall good power factor and a

D. Pimentel; M. B. Slima; A. Cheriti

2006-01-01

468

Z-source converter based zero voltage electronic load  

Microsoft Academic Search

This paper proposes a zero-voltage electronic load based on a Z-source converter. Electronic loads are a family of power converters used as a load in several applications such as photovoltaic [PV] cell performance tests or frequency control of stand alone micro generation. In PV cell performance tests; the zero voltage operation, caused by short circuit of the PV cell, is

Julio C. Rosas-Caro; Fang Z. Peng; Honnyong Cha; Craig Rogers

2008-01-01

469

Program Converts VAX Floating-Point Data To UNIX  

NASA Technical Reports Server (NTRS)

VAX Floating Point to Host Floating Point Conversion (VAXFC) software converts non-ASCII files to unformatted floating-point representation of UNIX machine. This is done by reading bytes bit by bit, converting them to floating-point numbers, then writing results to another file. Useful when data files created by VAX computer must be used on other machines. Written in C language.

Alves, Marcos; Chapman, Bruce; Chu, Eugene

1996-01-01

470

Intelligent dc-dc Converter Technology Developed and Tested  

NASA Technical Reports Server (NTRS)

The NASA Glenn Research Center and the Cleveland State University have developed a digitally controlled dc-dc converter to research the benefits of flexible, digital control on power electronics and systems. Initial research and testing has shown that conventional dc-dc converters can benefit from improved performance by using digital-signal processors and nonlinear control algorithms.

Button, Robert M.

2001-01-01

471

Power converter design for a fuel cell electric vehicle  

Microsoft Academic Search

This research is developed the electric vehicle by the fuel cell. Between fuel cell source and motor controller, we add new power converter, offer steady output voltage to motor controller and drive the direct current hub motor. Converter not only offers steady output voltage but it also combines with coupling inductance technology to battery charger. Besides offers energy to drive

Van-Tsai Liu; Jia-Wei Hong; Kuo-Ching Tseng

2010-01-01

472

Arc regime of a thermionic converter with different tungsten emitters  

Microsoft Academic Search

Thermionic converters operating in the arc regime are studied experimentally with the <110>, <112>, <100>, and <111> faces of tungsten single crystals and with a polycrystalline tungsten surface as emitters. The experiments are carried out under comparable conditions, and the electrode surfaces are monitored directly. In general, there is no clear correspondence between the output characteristics of the converter and

B. P. Varaksin; A. S. Titkov

1976-01-01

473

Record of middle Pleistocene climate change from Buck Lake, Cascade Range, southern Oregon - Evidence from sediment magnetism, trace-element geochemistry, and pollen  

USGS Publications Warehouse

Comparison of systematic variations in sediment magnetic properties to changes in pollen assemblages in middle Pleistocene lake sediments from Buck Lake indicates that the magnetic properties are sensitive to changes in climate. Buck Lake is located in southern Oregon just east of the crest of the Cascade Range. Lacustrine sediments, from 5.2 to 19.4 m in depth in core, contain tephra layers with ages of ???300-400 ka at 9.5 m and ???400-470 ka at 19.9 m. In these sediments magnetic properties reflect the absolute amount and relative abundances of detrital Fe-oxide minerals, titanomagnetite and hematite. The lacustrine section is divided into four zones on the basis of magnetic properties. Two zones (19.4-17.4 m and 14.5-10.3 m) of high magnetic susceptibility contain abundant Fe oxides and correspond closely to pollen zones that are indicative of cold, dry environments. Two low-susceptibility zones (17.4-14.5 m and 10.3-5.3 m) contain lesser amounts of Fe oxides and largely coincide with zones of warm-climate pollen. Transitions from cold to warm climate based on pollen are preceded by sharp changes in magnetic properties. This relation suggests that land-surface processes responded to these climate changes more rapidly than did changes in vegetation as indicated by pollen frequencies. Magnetic properties have been affected by three factors: (1) dissolution of Fe oxides, (2) variation in heavy-mineral content, and (3) variation in abundance of fresh volcanic rock fragments. Trace-element geochemistry, employing Fe and the immobile elements Ti and Zr, is utilized to detect postdepositional dissolution of magnetic minerals that has affected the magnitude of magnetic properties with little effect on the pattern of magnetic-property variation. Comparison of Ti and Zr values, proxies for heavy-mineral content, to magnetic properties demonstrates that part of the variation in the amount of magnetite and nearly all of the variation in the amount of hematite are due to changes in heavy-mineral content. Variation in the quantity of fresh volcanic rock fragments is the other source of change in magnetite content. Magnetic-property variations probably arise primarily from changes in peak runoff. At low to moderate flows magnetic properties reflect only the quantities of heavy minerals derived from soil and highly weathered rock in the catchment. At high flows, however, fresh volcanic rock fragments may be produced by breaking of pebbles and cobbles, and such fragments greatly increase the magnetite content of the resulting sediment. Climatically controlled factors that would affect peak runoff levels include the accumulation and subsequent melting of winter snow pack, the seasonality of precipitation, and the degree of vegetation cover of the land surface. Our results do not distinguish amont the possible contributions of these disparate factors.

Rosenbaum, J. G.; Reynolds, R. L.; Adam, D. P.; Drexler, J.; Sarna-Wojcicki, A. M.; Whitney, G. C.

1996-01-01

474

Proportional step size tracking analog-to-digital converter.  

PubMed

A new type of tracking analog-to-digital converter, which is capable of responding quickly to step changes in the input voltage, has been developed. The device produces an error signal which indicates the difference between the converter's state and the input signal level. This error signal is used to modify the converter's slew rate in such a way as to optimize convergence back to the tracking condition (i.e., the condition at which the converter's state accurately tracks the input signal). This error signal is also used to generate an accuracy code which indicates if the converter is accurately tracking the input signal, or if the converter is out of track, how many bits of the encoded data are actually significant. An eight-bit transient recorder was developed using the converter described above. The instrument was found to be capable of recording data at rates up to 10(6) points/s, and was observed to respond to step voltage changes within eight datum points. PMID:18647070

Last, T A

1980-03-01

475

Cost-effective segmented scintillating converters for hard x rays  

NASA Astrophysics Data System (ADS)

Thick segmented scintillating converters coupled to optical imaging detectors offer the advantage of large area, high stopping power sensors for high energy x-ray digital imaging. The recent advent of high resolution and solid state optical sensors such as amorphous silicon arrays and CCD optical imaging detectors makes it feasible to build large, cost effective imaging arrays. This technology, however, shifts the sensor cost burden to the segmented scintillators needed for imaging. The required labor intensive fabrication of high resolution, large area hard x- ray converters results in high cost and questionable manufacturability on a large scale. We report on recent research of a new segmented x-ray imaging converter. This converter is fabricated using vacuum injection and crystal growth methods to induce defect free, high density scintillating fibers into a collimator matrix. This method has the potential to fabricate large area, thick segmented scintillators. Spatial resolution calculations of these scintillator injected collimators show that the optical light spreading is significantly reduced compared to single crystalline scintillators and sub-millimeter resolution x- ray images acquired with the segmented converter coupled to a cooled CCD camera provided the resolution to characterize the converter efficiency and noise. The proposed concept overcomes the above mentioned limitations by producing a cost-effective technique of fabricating large area x-ray scintillator converters with high stopping power and high spatial resolution. This technology will readily benefit diverse fields such as particle physics, astronomy, medicine, as well as industrial nuclear and non-destructive testing.

Vasile, Stefan A.; Gordon, Jeffrey S.; Klugerman, Mikhail; Nagarkar, Vivek V.; Squillante, Michael R.; Entine, Gerald; Watson, Scott; Kauppila, Todd J.

1996-07-01

476

Weather satellite picture receiving stations, APT digital scan converter  

NASA Technical Reports Server (NTRS)

The automatic picture transmission digital scan converter is used at ground stations to convert signals received from scanning radiometers to data compatible with ground equipment designed to receive signals from vidicons aboard operational meteorological satellites. Information necessary to understand the circuit theory, functional operation, general construction and calibration of the converter is provided. Brief and detailed descriptions of each of the individual circuits are included, accompanied by a schematic diagram contained at the end of each circuit description. Listings of integral parts and testing equipment required as well as an overall wiring diagram are included. This unit will enable the user to readily accept and process weather photographs from the operational meteorological satellites.

Vermillion, C. H.; Kamowski, J. C.

1975-01-01

477

Design and operation of a thermionic converter in air  

SciTech Connect

An electrically heated thermionic converter has been designed, built and successfully tested in air. Several unique features were incorporated in this converter: an integral cesium reservoir, innovative ceramic-to-metal seals, a heat rejection system coupling the collector to a low temperature heat sink and an innovative cylindrical heater filament. The converter was operated for extended periods of time with the emitter at about 1900 K. the collector at about 700 K, and a power density of over 2 w(e)/sq. cm. Input power transients were run between 50% and 100% thermal power, at up to 1% per second, without instabilities in performance.

Horner, M.H.; Begg, L.L.; Smith, J.N. Jr. [General Atomics, San Diego, CA (United States); Geller, C.B.; Kallnowski, J.E. [Westinghouse Electric Corp., West Mifflin, PA (United States). Bettis Atomic Power Lab.

1995-01-01

478

Torque converter transient characteristics prediction using computational fluid dynamics  

NASA Astrophysics Data System (ADS)

The objective of this research is to investigate the transient torque converter performance used in an automobile. A new technique in computational fluid dynamics is introduced, which includes the inertia of the turbine in a three dimensional simulation of the torque converter during a launch condition. The simulation results are compared to experimental test data with good agreement across the range of data. In addition, the simulated flow structure inside the torque converter is visualized and compared to results from a steady-state calculation.

Yamaguchi, T.; Tanaka, K.

2012-11-01

479

Real-time incoherent-to-coherent optical converter  

NASA Technical Reports Server (NTRS)

Description of a real-time incoherent-to-coherent optical converter designed for application in image processing systems. The converter utilizes the photoconductivity effect of the compound Bi(12)SiO(20) for spatial modulation of electrical polarization in the compound. An optically absorbed write-in image is stored as an image polarization pattern in the device. Readout is effectuated electrooptically by using phase retardation in a polarized coherent light beam during the passage through the crystal. The operating mode required for achieving continuous image conversion with a high-speed recyclability is discussed. The performance characteristics of the converter are given and the fabrication technology is described.

Vohl, P.; Nisenson, P.; Oliver, D. S.

1973-01-01

480

Lead oxide glass tubing converters for gamma detection in MWPC  

SciTech Connect

PbO glass converters for the detection of gamma rays with MWPC have been investigated. The converters were made by fusing glass tubes stacked to form a close-packed array and were treated in a H/sub 2/ reduction process to provide a suitable electric drift field. Electron conversion efficiency, drift velocity, and spatial resolution of these arrays were investigated. Using 511 keV gamma rays, an electron conversion efficiency of 8% was established for the converter of 80% PbO by weight (1.4 mm inner diameter, 0.1 mm wall thickness and 2 cm thick).

Lum, G.K.; Green, M.I.; Perez-Mendez, V.; Tam, K.C.

1980-02-01

481

Implementation of a Hybrid AC–AC Direct Power Converter With Unity Voltage Transfer  

Microsoft Academic Search

This paper presents a novel hybrid direct power converter (HDPC) which overcomes the two main disadvantages of matrix converters: limited voltage transfer ratio and low immunity to grid disturbance. The proposed converter is formed by integrating a reversible auxiliary boost converter in the dc link of the two-stage matrix converter. Therefore, the HDPC can provide unity voltage transfer ratio even

Thiwanka Wijekoon; Christian Klumpner; Pericle Zanchetta; Patrick W. Wheeler

2008-01-01

482

Switching-ripple-based current sharing for paralleled power converters  

E-print Network

This paper presents the implementation and experimental evaluation of a new current-sharing technique for paralleled power converters. This technique uses information naturally encoded in the switching ripple to achieve ...

Perreault, David J.

483

Assembly processor program converts symbolic programming language to machine language  

NASA Technical Reports Server (NTRS)

Assembly processor program converts symbolic programming language to machine language. This program translates symbolic codes into computer understandable instructions, assigns locations in storage for successive instructions, and computer locations from symbolic addresses.

Pelto, E. V.

1967-01-01

484

Soft switched high frequency ac-link converter  

E-print Network

Variable frequency drives typically have employed dc voltage or current links for power distribution between the input and output converters and as a means to temporarily store energy. The dc link based power conversion systems have several inherent...

Balakrishnan, Anand Kumar

2009-05-15

485

Protection of semiconductor converters for controlled bypass reactors  

SciTech Connect

Possible ways of protecting thyristor converters in systems for magnetizing 110 - 500 kV controlled bypass reactors during switching and automatic reclosing are examined based on experience with the development of equipment, line tests, and mathematical modelling.

Dolgopolov, A. G., E-mail: andre.dolgopolov@mail.ru [JSC 'Elektricheskie upravlyaemye reaktory' (Russian Federation); Akhmetzhanov, N. G.; Karmanov, V. F. [JSC 'Energiya-T' (Russian Federation)

2010-05-15

486

26 CFR 1.305-6 - Distributions of convertible preferred.  

Code of Federal Regulations, 2010 CFR

...distribution of the stock; and (ii) taking...of the convertible stock, and the conversion...is consistent with market conditions at the time of distribution of the stock, there is no basis for predicting at what time and...

2010-04-01

487

16-Channel oversampled analog-to-digital converter  

SciTech Connect

Oversampled Analog-to-Digital conversion has been demonstrated to be an effective technique for high resolution analog-to-digital (A/D) conversion that is tolerant to process imperfections. The area and power budget of conventionally designed oversampled analog-to-digital converters has precluded their application from areas where a large number of low frequency signals need to be converted simultaneously. A new oversampled A/D design methodology is proposed to cut the area and power budget per channel of an oversampled analog-to-digital converter. The design and implementation of a 16-channel oversampled analog-to-digital converter is presented which can be used as the core of the multichannel data acquisition system. The prototype achieved 80 dB of signal-to-noise-plus-distortion over 1 kHz, [minus]80 dB of crosstalk and used less than 20 mW of power excluding clock generation.

Nadeem, S.; Sodini, C.G.; Lee, H.S. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Electrical Engineering and Computer Science)

1994-09-01

488

Non-synchronous control of self-oscillating resonant converters  

DOEpatents

A self-oscillating switching power converter has a controllable reactance including an active device connected to a reactive element, wherein the effective reactance of the reactance and the active device is controlled such that the control waveform for the active device is binary digital and is not synchronized with the switching converter output frequency. The active device is turned completely on and off at a frequency that is substantially greater than the maximum frequency imposed on the output terminals of the active device. The effect is to vary the average resistance across the active device output terminals, and thus the effective output reactance, thereby providing converter output control, while maintaining the response speed of the converter.

Glaser, John Stanley (Niskayuna, NY); Zane, Regan Andrew (Scotia, NY)

2002-01-01

489

Converting Sunlight to Mechanical Energy: A Polymer Example of Entropy.  

ERIC Educational Resources Information Center

This experiment/demonstration provides elementary through high school science students with hands-on experience with polymer entropy. Construction of a simple machine for converting light into mechanical energy is described. (RH)

Mathias, Lon J.

1987-01-01

490

Translator program converts computer printout into braille language  

NASA Technical Reports Server (NTRS)

Computer program converts print image tape files into six dot Braille cells, enabling a blind computer programmer to monitor and evaluate data generated by his own programs. The Braille output is printed 8 lines per inch.

Powell, R. A.

1967-01-01

491

Optimizing Ballast Design of Wave Energy Converters Using Evolutionary Algorithms  

E-print Network

University Corvallis, OR, 97331 nasroumo@engr.orst.edu Kagan Tumer Oregon State University Corvallis, OR, 97331 kagan.tumer@oregonstate.edu ABSTRACT Wave energy converters promise to be a viable alternative

Tumer, Kagan

492

Method for converting uranium oxides to uranium metal  

DOEpatents

A process is described for converting scrap and waste uranium oxide to uranium metal. The uranium oxide is sequentially reduced with a suitable reducing agent to a mixture of uranium metal and oxide products. The uranium metal is then converted to uranium hydride and the uranium hydride-containing mixture is then cooled to a temperature less than -100.degree. C. in an inert liquid which renders the uranium hydride ferromagnetic. The uranium hydride is then magnetically separated from the cooled mixture. The separated uranium hydride is readily converted to uranium metal by heating in an inert atmosphere. This process is environmentally acceptable and eliminates the use of hydrogen fluoride as well as the explosive conditions encountered in the previously employed bomb-reduction processes utilized for converting uranium oxides to uranium metal.

Duerksen, Walter K. (Norris, TN)

1988-01-01

493

Thermoelectric converter for SP-100 space reactor power system  

NASA Technical Reports Server (NTRS)

Conductively coupling the thermoelectric converter to the heat source and the radiator maximizes the utilization of the reactor and radiator temperatures and thereby minimizes the power system weight. This paper presents the design for the converter and the individual thermoelectric cells that are the building block modules for the converter. It also summarizes progress on the fabrication of initial cells and the results obtained from the preparation of a manufacturing plan. The design developed for the SP-100 system utilizes thermally conductive compliant pads that can absorb the displacement and distortion caused by the combinations of temperatures and thermal expansion coefficients. The converter and cell designs provided a 100 kWe system which met the system requirements. Initial cells were fabricated and tested.

Terrill, W. R.; Haley, V. F.

1986-01-01

494

20. VIEW OF TENNIS COURTS LOOKING SOUTH, WITH CONVERTED BASKETBALL ...  

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

20. VIEW OF TENNIS COURTS LOOKING SOUTH, WITH CONVERTED BASKETBALL COURT IN FOREGROUND. - Loring Air Force Base, Alert Area, Southeastern portion of base, east of southern end of runway, Limestone, Aroostook County, ME

495

A Single-stage Boost-Flyback PFC Converter  

Microsoft Academic Search

This paper presents a novel single-stage single-switch power factor correction (PFC) converter. The proposed topology is derived by combining a boost cell and a flyback cell into one power stage. In this converter, the transformer in the flyback cell has two-coupling primary windings, which have the same turns. Two bulk storage capacitors are used to store the power energy from

Zhao Qinglin; Wen Yi; Wu Weiyang; Chen Zhe

2006-01-01

496

Dual Series-Resonant Active-Clamp Converter  

Microsoft Academic Search

A dual series-resonant active-clamp dc-dc converter is proposed to obtain high efficiency. The proposed converter employs an active-clamp technique, while a series-resonant scheme controls the output voltage with the complementary pulsewidth modulation controller. The active-clamp circuit serves to recycle the energy stored in the leakage inductance or the magnetizing inductance and provides zero-voltage turn-on switching. The voltage stresses of the

Lee Jong-Jae; Kwon Jung-Min; Kim Eung-Ho; Kwon Bong-Hwan

2008-01-01

497

Development, evaluation, and design applications of an AMTEC converter model  

E-print Network

falls within the capabilities of the particular AMTEC converter. External Load BASE Q ~ S Q g Qa e Qa QN Porous Current Collector (Anode) Porous Electrode (Cathode) Figure 2. Beta tube wall cross section with illustration of electrocheroical... falls within the capabilities of the particular AMTEC converter. External Load BASE Q ~ S Q g Qa e Qa QN Porous Current Collector (Anode) Porous Electrode (Cathode) Figure 2. Beta tube wall cross section with illustration of electrocheroical...

Spence, Cliff Alan

2012-06-07

498

Coupled inductor boost converter with input and output ripple cancellation  

Microsoft Academic Search

The authors describe the HS601 spacecraft battery discharge controller (BDC), a fully redundant 100 kHz boost converter which provides up to 2 kW at 50.5 VDC from a 32 cell battery (32-45 VDC). The converter is designed to be connected in parallel with a second unit to provide up to 4 kW to the spacecraft to the spacecraft bus during

Robert Martinelli; Christopher Ashley

1991-01-01

499

New Magnet Power Converters for the SRS at Daresbury  

Microsoft Academic Search

A programme to replace 25 year old magnet power converters on the SRS at Daresbury is nearing completion. The roller regulator converters recovered from the NINA synchrotron beamlines are being replaced by commercially available switch-mode units for those rated up to lOkW, and by thyristor phase controlled units for those rated from 90kW to 750kW. The latter are designed to

D. E. Poole; S. A. Griffiths; M. T. Heron

500

Adaptive control of power converters using Digital Network Analyzer Techniques  

Microsoft Academic Search

We describe a new method for design of adaptive controls for switching power converters that leverages the information-rich frequency response data obtained using the correlation-based analysis dubbed Digital Network Analyzer Technique. Compared to existing single-frequency based adaptive control methods such as limit-cycle and relay- feedback based autotuning, this method provides a unified approach to target many distinct problems plaguing converter

Adam Barkley; Roger Dougal; Enrico Santi

2011-01-01