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1

Bidirectional buck boost converter  

DOEpatents

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

Esser, A.A.M.

1998-03-31

2

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

3

State controller for buck converter  

Microsoft Academic Search

The average state space model of the buck converter has been used in order to design the PI and state controller. Simple analytical expressions in terms of the circuit components are derived for frequency responses of time averaged (continuous) power-stage for use in designing and understanding the behavior of corresponding switched power stage. Such obtained models enable the designing of

Suzana Uran; M. Milanovic

2003-01-01

4

Fractional order control strategies for power electronic buck converters  

Microsoft Academic Search

This paper presents several alternative methods for the control of power electronic buck converters applying fractional order control (FOC). For achieving this goal, the controller design will be carried out by two strategies. On the one hand, the design of a linear controller for the DC\\/DC buck converter will be considered. In that sense, the Bode's ideal function will be

A. J. Calderón; Blas M. Vinagre; Vicente Feliú Batlle

2006-01-01

5

Integrated ZVS POL synchronous buck converter for portable applications  

Microsoft Academic Search

This paper proposes an integrated, high switching frequency, zero-voltage-switching quasi-square-wave (ZVS-QSW) point of load (POL) buck converter for portable applications. The design and analysis of a fully integrated synchronous buck dc-dc converter with integrated inductor is presented. The converter has been optimized to convert 5V input voltage to 1.2V at 3A maximum load current at a 5MHz switching frequency. An

Yasser Nour; Mohamed Orabi; Ashraf Lotfi

2010-01-01

6

Control of Switched Capacitor Step-Down Buck Converter  

Microsoft Academic Search

In this paper a simple two-loop voltage mode control scheme for the switched capacitor step down buck converter is proposed. This is a voltage-mode control scheme in which the external saw-tooth generator for the PWM generation is not required. The controller implementation requires only a single error amplifier and gives almost current mode control performance. The proposed switched capacitor converter

Mummadi Veerachary

2006-01-01

7

Buck and boost derived converter for livestock\\/poultry stunning applications  

Microsoft Academic Search

This paper proposes a buck and boost derived converter associated with a full-bridge inverter for livestock\\/poultry stunning applications. The derived converter is formed by combining buck and boost converters to step up or step down input voltage. Compared with the conventional buck-boost converter, the proposed converter can raise efficiency of 4-6% under full load condition. In the paper, mechanism of

T.-F. Wu; S.-Y. Tseng; J.-S. Hu; Y.-M. Chen

2006-01-01

8

A Noninverting Buck–Boost DC–DC Switching Converter With High Efficiency and Wide Bandwidth  

Microsoft Academic Search

A novel dc-dc switching converter consisting of a boost stage cascaded with a buck converter with their coils magnet- ically coupled is presented. The disclosed converter has the same step-up or step-down voltage conversion properties than the sin- gle inductor noninverting buck-boost converter but exhibits non- pulsating I\\/O currents. The converter control-to-output transfer function is continuous between operation modes if

Carlos Restrepo; Javier Calvente; Angel Cid-Pastor; Abdelali El Aroudi; Roberto Giral

2011-01-01

9

Flyback Transformer Based Transient Suppression Method for Digitally Controlled Buck Converters  

E-print Network

] and extra switches, which considerably increases cost and consumes PCB real estate. A single phase voltageFlyback Transformer Based Transient Suppression Method for Digitally Controlled Buck Converters-- A current-programmed mode (CPM) digitally controlled buck converter with a flyback transformer is proposed

Prodiæ, Aleksandar

10

Modeling, analysis, and application of buck converters in discontinuous-input-voltage mode operation  

Microsoft Academic Search

By adding a suitable LC filter to the input of a buck power converter, it is possible to force the converter into discontinuous-input-voltage mode operation. A buck power converter in this mode of operation has useful properties such as power factor correction and soft turn-off switching. The operation, modeling, low-frequency behavior, and application of the power converter are studied. Experimental

Y. S. Lee; S. J. Wang; S. Y. R. Hui

1997-01-01

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

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

NASA Astrophysics Data System (ADS)

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

Rahman, S.; Lee, F. C.

13

Tapped-inductor buck converter for high-step-down DC-DC conversion  

Microsoft Academic Search

The narrow duty cycle in the buck converter limits its application for high-step-down dc-dc conversion. With a simple structure, the tapped-inductor buck converter shows promise for extending the duty cycle. However, the leakage inductance causes a huge turn-off voltage spike across the top switch. Also, the gate drive for the top switch is not simple due to its floating source

Kaiwei Yao; Mao Ye; Ming Xu; Fred C. Lee

2005-01-01

14

A quasi-resonant zero-current-switching buck PWM converter using a nonlinear resonant inductor  

Microsoft Academic Search

This paper shows a lossless commutation cell that uses a nonlinear resonant inductor. The principle of the nonlinear resonant inductor is applied to a QRC-ZCS-PWM buck converter with the objective of reducing the peak current in the main switch, maintaining the ZCS characteristics of the QRC-ZCS-PWM buck converter. This is achieved by unsaturating the core of the nonlinear resonant inductor

Elcio Precioso de Paiva; Luiz Carlos de Freitas; Valdeir Jose Farias; E. A. A. Coelho

1996-01-01

15

A novel winding-coupled buck converter for high-frequency, high-step-down DC-DC conversion  

Microsoft Academic Search

This paper analyzes the fundamental limitations of the buck converter for high-frequency, high-step-down dc-dc conversion. Further modification with additional coupled windings in the buck converter yields a novel topology, which significantly improves the efficiency without compromising the transient response. An integrated magnetic structure is proposed for these windings so that the same magnetic cores used in the buck converter can

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

2005-01-01

16

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

Microsoft Academic Search

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

Chen Jiawei; Chen Jie; Gong Chunying

2009-01-01

17

Design and Implementation of Low Power Smart PV Energy System for Portable Applications Using Synchronous Buck Converter  

Microsoft Academic Search

In this paper, synchronous buck converter based PV energy system for portable applications, especially low power device applications such as charging mobile phone batteries are considered. The converter topology used here is soft switching technique to reduce the switching losses which is found prominently in the conventional buck converter, thus efficiency of the system is improved and the heating of

B. Chitti Babu; Sriharsha; Ashwin Kumar; Nikhil Saroagi; S. R. Samantaray

2011-01-01

18

Nonisolation Soft-Switching Buck Converter With Tapped-Inductor for Wide-Input Extreme Step-Down Applications  

Microsoft Academic Search

In this paper, a new zero-voltage switching (ZVS) buck converter with a tapped inductor (TI) is proposed. This converter improves the conventional tapped inductor critical conduction mode buck converters that have the ZVS operation range determined by the TI turn ratios. It includes another soft switching range extension method, the current injection method, which gives an additional design freedom for

Joung-Hu Park; Bo-Hyung Cho

2007-01-01

19

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

E-print Network

Two phase interleaved buck converter for driving high power LEDs Szymon Bczkowski, Stig Munk as a constant, regulated current source which increases luminous efficacy of LED compared to PWM dimmed system. Because of the low dynamic resistance of LEDs the duty cycle of the converter does not change greatly

Munk-Nielsen, Stig

20

Near Time-Optimal Transient Response in DC-DC Buck Converters Taking into Account the Inductor Current Limit  

E-print Network

Near Time-Optimal Transient Response in DC-DC Buck Converters Taking into Account the Inductor}@colorado.edu Abstract ­ This paper analyzes the general problem of inductor current limitation in the time-optimal load transient response of a DC-DC buck converter. The concept of current- limited, time-optimal control (CL

21

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

E-print Network

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

Sun, Jian

22

Influence of PWM structure on the dynamics of a ZAD-controlled buck converter  

Microsoft Academic Search

This paper focuses on the dynamical response of the ZAD-controlled buck converter under the variation of the PWM structure. Numerical analysis shows that the system can exhibit supercritical and subcritical period-doubling bifurcations, depending on the parameter values. This indicates that the ZAD technique can be highly dependent on the PWM composition. I. I NTRODUCTION A dc-dc converter is an electronic

Maria Belen D'Amico; Fabiola Angulo

2011-01-01

23

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

Microsoft Academic Search

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

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

2006-01-01

24

FPGA Implementation of Digital Controller for DC-DC Buck Converter  

Microsoft Academic Search

This paper describes a complete digital controlled dc-dc buck converter performed by FPGA circuitry. All tasks as are analog to digital conversion, control algorithm and pulse width modulation were implemented in the FPGA. This approach enables high-speed dynamic response and programmability of the controller without external passive components and more the controller structure could be changed from linear to non-linear

Miro Milanovic; Mitja Truntic; Primoz Slibar

2005-01-01

25

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

26

Buck converter small-signal models and dynamics: comparison of quasi-resonant and pulsewidth modulated switches  

Microsoft Academic Search

The generalized canonical model obtained from extended state-space averaging is used as a design tool for the evaluation of the buck converter dynamics in different switching schemes. Designs are given at a specified constant conversion ratio and load for the pulse width modulated, zero current, zero voltage, and nonlinear resonant switch full- and half-wave converters. The small signal equivalent circuit

Arthur F. Witulski

1991-01-01

27

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

28

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

NASA Astrophysics Data System (ADS)

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

Danzhu, Lü; Jiale, Yu; Zhiliang, Hong

2013-02-01

29

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

30

Advanced Energy Conversion System Using Sinusoidal Voltage Tracking Buck-Boost Converter Cascaded Polarity Changing Inverter  

NASA Astrophysics Data System (ADS)

This paper presents an advanced power converter employs a sinusoidal voltage absolute value tracking buck-boost DC-DC converter in the first power processing stage and a polarity changing full-bridge inverter in the second stage. The proposed power conversion system has the capability of delivering sinusoidal output and input current with unity power factor and good output voltage regulation. Consequently, the complete voltage regulator system, which is mainly suitable for new energy generation systems as well as energy storage systems, can be constructed compactly and inexpensively without DC link electrolytic capacitor. Also, the paper presents an auxiliary passive resonant circuit for soft switching operation. Simulation results using PSIM software are presented to verify the operation principles and feasibility of the proposed power conversion system.

Ahmed, Nabil A.

2011-06-01

31

Current-Mode Control of a Coupled-Inductor Buck–Boost DC–DC Switching Converter  

Microsoft Academic Search

This paper deepens in the study of the recently described coupled-inductor buck–boost converter. The output voltage of this dc–dc converter can be regulated above and\\/or below its input voltage with high efficiency and wide bandwidth. The control of the input and\\/or output nonpulsating converter currents is addressed in this paper. The small-signal control-to-input\\/output-current transfer functions in open-loop permits the design

Carlos Restrepo; Javier Calvente; Alfonso Romero; Enric Vidal-Idiarte; Roberto Giral

2012-01-01

32

PID controller modifications to improve steady-state performance of digital controllers for buck and boost converters  

Microsoft Academic Search

The sensitivity of the analog-to-digital converter and inherent time delay in a digital controller can degrade the steady-state performance of a DC-DC power converter. Analog PID controllers were designed for prototype buck and boost converters and then implemented on a TI DSP. Three modifications to the digital PID controllers were investigated to improve their steady-state performance. The modifications were a

Liping Guo; John Y. Hung; R. M. Nelms

2002-01-01

33

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

E-print Network

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

Friedman, Eby G.

34

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

35

Interleaved buck-boost converter with single-capacitor turn-off snubber using coupled inductor for stunning poultry applications  

Microsoft Academic Search

This paper proposes an interleaved buck-boost converter with a single-capacitor turn-off snubber to reduce the switching loss at turn-off transition and to limit rising rate of voltages across switches for reducing spike voltage. In addition, the proposed converter adopts coupled inductor to attain a high step-up voltage ratio and operates in an interleaved fashion to reduce output current ripple. As

S.-Y. Tseng; Y.-H. Su; J.-Z. Shiang; C.-M. Yang; S.-Y. Fan

2008-01-01

36

Modelling and analysis of a matrix-reactance frequency converter based on buck-boost topology by DQ0 transformation  

Microsoft Academic Search

This paper deals with a three-phase matrix-reactance frequency converter (MRFC). The analysed MRFC topology is based on buck-boost matrix-reactance chopper (MRC) one with source synchronous connected switches (LSCS) set arranged as in the step-up matrix converter (MC). The MRFC in question makes it possible to obtain a load output voltage much greater than the input voltage. Presented in this paper

P. Szczesniak; Z. Fedyczak; M. Klytta

2008-01-01

37

Non-isolation Soft-switching Buck Converter with Tapped-Inductor for Wide-input Extreme Step-down applications  

Microsoft Academic Search

In this paper, a new zero-voltage switching (ZVS) buck converter with a tapped-inductor is proposed. This converter improves the conventional tapped inductor critical conduction mode (CRM) buck converters that have the ZVS operation range determined by the tapped-inductor turn ratios. It includes another soft switching range extension method, the current injection (CI) method, which gives an additional design freedom for

J. H. Park; B. H. Cho

2005-01-01

38

Minimized transient and steady-state cross regulation in 55nm CMOS single-inductor dual-output (SIDO) step-down DC-DC converter  

Microsoft Academic Search

A single-inductor dual-output (SIDO) step-down converter with continuous conduction mode (CCM) control is proposed for high efficiency system-on-a-chip (Soc) integration. The cross regulation in steady-state output voltage ripple, which is rarely mentioned, is effectively reduced as well as in transient response. The low-voltage energy distribution controller (LV-EDC) circuit guarantees good voltage regulation and low output voltage ripple simultaneously. In addition,

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

2010-01-01

39

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

Microsoft Academic Search

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

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

2011-01-01

40

A novel winding coupled-buck converter for high-frequency, high step-down DC\\/DC conversion  

Microsoft Academic Search

The buck converter is popularly used for stepdown DC\\/DC conversion when there is no isolation requirement. However, for high step-down, large output current applications such as voltage regulation modules (VRMs), it is no longer suitable, especially at high switching frequencies. The too-small duty cycle and large switching-related loss limit its performance. This paper proposes a novel topology, which is based

Kaiwei Yao; Yu Meng; Fred C. Lee

2002-01-01

41

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

E-print Network

is currently gaining importance in mobile handsets, where it is used to provide wide adaptive power supply and SW2 nodes in Fig. 1.In closed loop operation, the PWM discontinuity around 100% buck or 0% boost duty

42

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

43

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

Microsoft Academic Search

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

Jia Wei; Fred C. Lee

2003-01-01

44

Analysis and design of the quadratic buck-boost converter as a high-power-factor driver for power-LED lamps  

Microsoft Academic Search

In this paper the quadratic buck-boost (QBB) converter is proposed as a high-power-factor off-line power supply for power-LED lamps. The QBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains providing high power factor and good efficiency. In the paper, the QBB converter is analyzed and a design methodology

J. Marcos Alonso; Juan Viña; David Gacio; Lidia Campa; Gilberto Martínez; René Osorio

2010-01-01

45

Analysis and Design of the Integrated Double Buck–Boost Converter as a High-Power-Factor Driver for Power-LED Lamps  

Microsoft Academic Search

In this paper, an integrated double buck-boost (IDBB) converter is proposed as a high-power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design

J. Marcos Alonso; Juan Vina; David Gacio Vaquero; Gilberto Martinez; René Osorio

2012-01-01

46

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

47

A detailed analytical analysis of a passive resonant snubber cell perfectly constructed for a pulse width modulated d.c.-d.c. buck converter  

Microsoft Academic Search

In this paper, a detailed analytical analysis of a passive resonant snubber cell that is perfectly constructed for a pulse width modulated (PWM) d.c.-d.c. buck converter is proposed. This snubber cell provides a larger overall efficiency and a wider load range than most of the active snubber cells presented previously, and has a simple structure and low cost. The operation

H. Bodur; A. Bakan; M. Baysal

2003-01-01

48

A Universal-Input Single-Stag2e High-Power-Factor Power Supply for HB-LEDs Based on Integrated Buck–Flyback Converter  

Microsoft Academic Search

Due to the high rise in luminous efficiency that high- brightness light-emitting diodes (HB-LEDs) have experienced in recent years, many new applications have been researched. This paper covers a streetlight LED application using the offline in- tegrated buck-flyback converter (IBFC) developed in previous works. In this application, the converter is used to provide power- factor correction from a universal ac

David Gacio; J. Marcos Alonso; Antonio J. Calleja; Jorge Garcia; Manuel Rico-Secades

2011-01-01

49

20 kW water-cooled prototype of a buck-boost bidirectional DC-DC converter topology for electrical vehicle motor drives  

Microsoft Academic Search

In brushless DC motor drives devoted to electric vehicles (EVs) a bi-directional DC-DC power converter can be used to control suitably both motoring and regenerative braking operations in order to improve the motor drive performance. In consideration of such an application, this paper deals with the experimental study of a buck-boost bi-directional DC-DC power converter topology which has been conceived

F. Caricchi; F. Crescimbini; A. Di Napoli

1995-01-01

50

Monolithic integration of a 3-level DCM-operated low-floating-capacitor buck converter for DC-DC step-down donversion in standard CMOS  

Microsoft Academic Search

This paper addresses the fully monolithic integration of a 3-level 2-phase buck converter for DC-DC step-down conversion in standard CMOS. First it is shown a design-oriented analysis of the converter considering DCM mode (due to PFM operation for low output currents) and with low values of the floating capacitor (to improve integrability). At transistor-level, a self-driving scheme is proposed which

Gerard Villar; Eduard Alarcón

2008-01-01

51

A novel on-chip soft-started DC-DC buck converter for biomedical applications  

Microsoft Academic Search

An integrated pulse width modulation (PWM) step-down CMOS DC-DC converter with integrated power switches and a novel on-chip soft-start circuit is presented in this paper. This converter consists of internal ramp signal generator, comparator, error amplifier, PWM control scheme, and a soft-start scheme. The soft-start circuit can produce a slowly rising output voltage without extra clock or any external component

Ai-Ping Yao; Hai-Xi Li; Jin-yong Zhang; Lei Wang

2012-01-01

52

A battery-free 225 nW buck converter for wireless RF energy harvesting with dynamic on\\/off time and adaptive phase lead control  

Microsoft Academic Search

A battery-free 225 nW buck converter is implemented by using 0.25-?m CMOS process with die area of 0.21 mm 2 . The dynamic on\\/off time (DOOT) technique can predict the on\\/off time at different input voltage, as well as suppress static power in the idle period. In addition, the adaptive phase lead mechanism can improve the initial delay from the

Chun-Yu Hsieh; Yu-Huei Lee; Yao-Yi Yang; Tzu-Chi Huang; Ke-Horng Chen; Chen-Chih Huang; Ying-Hsi Lin

2011-01-01

53

A multi-level buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multilevel diode rectifier and a multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier has a few

M. L. Zhang; B. Wu; Y. Xiao; F. Dewinter; R. Sotudeh

1999-01-01

54

A multilevel buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multi-level diode rectifier and a modified multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier features reliable

Michael Lan Zhang; Bin Wu; Yuan Xiao; F. A. Dewinter; R. Sotudeh

2002-01-01

55

Resonant assisted buck converter for offline driving of high brightness LED replacement lamps  

Microsoft Academic Search

LEDs are prospective successors of incandescent lamps with high efficacy and long lifetime. To improve the overall luminair efficacy and lifetime, the power efficiency and lifetime of LED ballast become important factors. Efficiency gain in transformerless power converter appears attractive for applications without isolation. Driving solid-state LED bulbs such as in PAR30 style from universal mains necessitates a high voltage

Xiaohui Qu; Siu-Chung Wong; Chi K. Tse

2010-01-01

56

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

E-print Network

is an indication of the car instantaneous situation. When the vehicle is accelerating, the battery voltage goes, similar in shape and size to a Chevrolet S-10. This vehicle was already converted to an electric car electrochemical batteries, to improve the transient performance of an electric vehicle, and to increase the useful

Catholic University of Chile (Universidad Católica de Chile)

57

Resonance-Assisted Buck Converter for Offline Driving of Power LED Replacement Lamps  

Microsoft Academic Search

LEDs are potential successors of incandescent lamps with high luminous efficacy and long lifetime. To improve the over- all luminair efficacy and lifetime, the power efficiency and life- time of LED ballasts become important factors. Efficiency gain in transformerless power converters appears attractive for applica- tions without isolation. Driving solid-state LED bulbs in an exist- ing lighting fixture such as

Xiaohui Qu; Siu-Chung Wong; Chi K. Tse

2011-01-01

58

A fast time domain digital simulation technique for power converters - Application to a buck converter with feedforward compensation  

NASA Technical Reports Server (NTRS)

Small signal analysis was performed earlier to demonstrate the marked improvement of dynamic properties and stability margins of a switching regulator employing a novel feedforward input filter compensation scheme. A large signal nonlinear recurrent time domain model is presented for the converter to analyse the transient response due to a step input change with and without the presence of the proposed feedforward loop. The results are verified with experimental data.

Kelkar, S. S.; Lee, F. C.

1984-01-01

59

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

Microsoft Academic Search

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

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

2011-01-01

60

Parametric Average-Value Modeling of Multiple-Input Buck Converters  

Microsoft Academic Search

Average-value modeling of DC-DC converters is an indispensable tool for analysis of power electronic systems. However, analytical derivation of accurate models may be quite challenging especially when multiple modes and the circuits' parasitics are considered. Recently, a computer-aided average-value modeling approach has been proposed in the literature, wherein the average model has a well-defined structure and is constructed with the

Ali Davoudi; Juri Jatskevich; Patrick L. Chapman

2007-01-01

61

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

62

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

NASA Astrophysics Data System (ADS)

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

Park, Hyunbin; Sim, Minseob; Kim, Shiho

2015-01-01

63

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

Microsoft Academic Search

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

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

1998-01-01

64

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

65

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

E-print Network

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

Gregory, L.; Dyer, P.

66

Simple topologies of PWM AC-AC converters  

Microsoft Academic Search

This letter proposes a new family of simple topologies of PWM AC-AC converters with minimal switches. With extension from the basic DC-DC converters, a series of AC-AC converters such as buck, boost, buck-boost, Cuk, and isolated converters are obtained. By PWM duty ratio control, they become a \\

Fang Zheng Peng; Lihua Chen; Fan Zhang

2003-01-01

67

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

68

An integrated step-down DC-DC converter with low output voltage ripple  

Microsoft Academic Search

An integrated low-output-ripple step-down DC-DC converter, which cascades a Buck converter with a low-dropout regulator (LDO), is presented. The output of the Buck converter can be used to supply digital circuits, while the LDO output is used to power analog circuits. The designed Buck converter can adaptively and automatically switch between the pulse-width modulation (PWM) and pulse-frequency modulation (PFM) to

Yi-Ting Lee; Chia-Ling Wei; Chin-Hong Chen

2010-01-01

69

Wilbur "Buck" Clayton Collection  

NSDL National Science Digital Library

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

70

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

71

Single-stage single-switch PFC converter with extreme step-down voltage conversion ratio  

Microsoft Academic Search

This paper presents a new single-stage singleswitch (S4) high power factor correction (PFC) AC\\/DC converter suitable for low power applications (< 150 W) with a universal input voltage range (90-265 Vrms). The proposed topology integrates a buck-boost input current shaper followed by a buck and a buck-boost converter, respectively. As a result, the proposed converter can operate with larger duty

Esam H. Ismail; Mustafa A. Al-Saffar; Ahmad J. Sabzali

2009-01-01

72

Cal Poly SuPER System Photovoltaic Array Universal DC-DC Step Down Converter  

Microsoft Academic Search

Standard converter topologies are usually presented with a voltage source as the input supply to the converters. However, a photovoltaic (PV) array has the I-V characteristics of a current source not a voltage source. This thesis details the design process of modifying the standard Buck and synchronous Buck converter topologies to function with either a voltage or current source input,

Joseph Witts

2008-01-01

73

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

74

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

75

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

76

Inductor-free low power step-down dc-dc switching voltage converter  

Microsoft Academic Search

In low power IC systems, low-dropout, buck and switched-capacitor voltage converters are the three alternative power sources. This paper presents an inductor-free switching voltage converter which possesses the merits of aforementioned converters. It features inductor-less structure like SC based switching converter, adjustable output by PWM mechanism like buck converter, and OPA based structure like LDO. Circuit modeling shows that the

Chun-Hsun Wu; Le-Ren Chang-Chien

2008-01-01

77

A Non-Insulated Step-Up\\/Down DC-DC Converter with Wide Range Conversion  

Microsoft Academic Search

In this paper an approach of a step-up\\/down dc-dc converter with wide range conversion called Boost2-Buck is presented. The proposed converter presents nonpulsating input and output current. It has operations equivalent to a cascade converter consisting of two boost converter and one buck converter, but with the advantage of using single active switch. Mathematical analysis and experimental results are presented

Jonas R. de Britto; Luiz C. de Freitas; Valdeir J. Farias; Ernane A. A. Coelho; João B. Vieira Jr

2009-01-01

78

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

79

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

80

Landowners lead successful Buck Creek restoration  

E-print Network

26 tx H2O Fall 2012 Story by Kathryn S. Boutwell Landowners in the Buck Creek watershed in the Texas Panhandle were the driving force behind the successful restoration of the watershed and its removal from the Texas Commission on Environ....? Located in the Texas Panhandle counties of Donley, Collingsworth and Childress, Buck Creek was originally listed as being impaired for elevated bacteria levels in #30;#29;#29;#29;. Lucas Gregory, the Texas Water Resources Institute?s (TWRI) project...

Boutwell, Kathryn S.

2012-01-01

81

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

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 dining flexibility. New Bear Bucks accounts can be opened with as little as $20! FEATURES OF BEAR BUCKS

Chu, Xi

82

Advanced buck converter power supply ABCPS for APT  

Microsoft Academic Search

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

T. Overett; E. Bowles

1998-01-01

83

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

84

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

85

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

86

Step down converter with hysteretic current control for welding applications  

Microsoft Academic Search

The present paper deals with a buck power converter used to control the current during a welding process. The voltaic arc is modeled by a variable resistance in series with a voltage source. The step-down DC-DC power converter is connected to the output of a conventional electromagnetic power source and a controls the energy flux to the welding process. An

SERGIO MARQUES; CICERO CRUZ; F. Antunes; JESUALDO FARIAS

1997-01-01

87

Bacterial Monitoring for the Buck Creek Watershed  

E-print Network

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

88

The Buck Institute Turned to Geothermal  

E-print Network

The Buck Institute Turned to Geothermal Heating and Cooling for Significant Savings on Energy with the goal of sustaining the healthy years of life... #12;Geothermal Exchange #12;§ Cooling Tower: One. Other Challenges to the Original Central Plant: #12;The geothermal well field replaces the cooling tower

89

A digital dither controlled step-up\\/step-down DC-DC converter with smooth transition  

Microsoft Academic Search

A step-up\\/step-down DC-DC converter with high efficiency and small output voltage ripple is proposed in this paper. To reduce the switching loss and improve the efficiency, the converter operates in buck or boost mode when the input voltage is much higher or lower than the output voltage. However, a large output voltage ripple appears at the boundary of buck mode

Yanzhao Ma; Hongyi Wang; Guican Chen

2011-01-01

90

A novel method for smooth transition in step-up\\/step-down DC-DC converter  

Microsoft Academic Search

This paper presents a step-up\\/step-down converter with a novel control scheme based on noninverting buck-boost converter. The control scheme is used to obtain a transition mode and implement smooth transition between buck mode and boost mode. The transition mode is adopted to improve the linearity between the output voltage and the control voltage. With the proposed control method, the output

Yanzhao Ma; Hongyi Wang; Guican Chen; Fan Qu

2009-01-01

91

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

92

Laboratory and Workplace Assessments of Rivet Bucking Bar Vibration Emissions.  

PubMed

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

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

2014-11-01

93

Design considerations and performance evaluation of a 6kW, single-switch, three-phase, high-power-factor, multi-resonant, zero-current-switching buck rectifier  

Microsoft Academic Search

The paper provides a complete design procedure of the multi-resonant, zero-current-switched (ZCS), high-power factor (HPF) buck rectifier for telecommunication applications and presents extensive experimental evaluations of its performance. The evaluation was performed on a 6 kW prototype operating from a 380 V±10%, three-phase input voltage. The evaluation results demonstrate that the input current shaping using the multi-resonant buck power converter

Yungtaek Jang; M. M. Jovanovic

1997-01-01

94

System-Level Requirements of DC-DC Converters for Dynamic Power Supplies of Power Amplifiers  

E-print Network

fully discharged, a step-down (buck) converter would be needed for lower voltages, during power back the supply voltage from the fixed battery supply using a DC-DC converter, the PA can be operated with highSystem-Level Requirements of DC-DC Converters for Dynamic Power Supplies of Power Amplifiers

Rincon-Mora, Gabriel A.

95

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

NASA Technical Reports Server (NTRS)

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

Birchenough, Arthur G.

2003-01-01

96

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

NASA Technical Reports Server (NTRS)

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

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

1973-01-01

97

Double-ended transformer-based multi-phase converters  

Microsoft Academic Search

Conventional multi-phase buck converters, as one of today's major solutions for high current low voltage telecom and microprocessor power supplies, face severe challenges as the converter duty cycle becomes extremely small, and power density\\/switching frequency becomes higher and higher. This paper introduces non-isolated transformer-based multi-phase converter solutions that extend duty cycles to a favorable range to improve both steady state

Jason Guo

2003-01-01

98

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

NASA Astrophysics Data System (ADS)

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

Al-Rabadi, Anas N.

2009-10-01

99

Supervised neural computing and LMI optimisation for order model reduction-based control of the Buck switching-mode power supply  

Microsoft Academic Search

This article introduces a new method of intelligent control to control the Buck converter using a newly developed small-signal model of the pulse width modulation (PWM) switch. The new method uses a recurrent supervised neural network to estimate certain parameters of the transformed system matrix []. Then, a numerical algorithm used in robust control called the linear matrix inequality (LMI)

Anas N. Al-Rabadi; Othman M.-K. Alsmadi

2011-01-01

100

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

Microsoft Academic Search

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

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

2010-01-01

101

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

102

Two-parameter bifurcation curves in power electronic converters1  

E-print Network

then consider a DC/DC buck (step-down) converter controlled by the ZAD (zero-average dynamics) strategy. The ZAD strategy sets the duty cycle, d (the length of time the input voltage is applied across an inductance are vref , a reference voltage that the circuit is required to follow, and ks, a time constant which

Politècnica de Catalunya, Universitat

103

Coupled Dual Interleaved Flyback Converter for High Input Voltage Application  

E-print Network

- This paper proposes an integrated magnetic DC-DC converter suitable for high input voltage application electronics. For large step-down power conversions, such as 48V to 1V, buck mode isolated topologies have or EE core is used for all the magnetic components, including the input inductor, the step-down

Lehman, Brad

104

Soft switching active snubbers for DC/DC converters  

SciTech Connect

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

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

1996-09-01

105

Multiphase LLC Series Resonant Converter for Microprocessor Voltage Regulation  

Microsoft Academic Search

In order to further reduce the power loss, and increase the computation speed, future microprocessors desires lower voltage, higher current, tighter voltage regulation, and faster transient from their voltage regulators. In the last decade, interleaved buck converters have been studied and used extensively for powering microprocessors. Due to their inherent limitations in current sharing, capacitor size, step down ratio, and

Taotao Jin; Keyue Smedley

2006-01-01

106

dc analysis and design of zero-voltage-switched multi-resonant converters  

NASA Astrophysics Data System (ADS)

Recently introduced multiresonant converters (MRCs) provide zero-voltage switching (ZVS) of both active and passive switches and offer a substantial reduction of transistor voltage stress and an increase of load range, compared to their quasi-resonant converter counterparts. Using the resonant switch concept, a simple, generalized analysis of ZVS MRCs is presented. The conversion ratio and voltage stress characteristics are derived for basic ZVS MRCs, including buck, boost, and buck/boost converters. Based on the analysis, a design procedure that optimizes the selection of resonant elements for maximum conversion efficiency is proposed.

Tabisz, Wojciech A.; Lee, Fred C.

107

A SPICE model for current mode PWM converters operating under continuous inductor current conditions  

Microsoft Academic Search

A SPICE simulation model of current-mode pulse-width modulation (PWM) converters operating in the continuous mode is described and tested against analytical expressions and experimental data for buck and boost converters. The simulation model is also used to compare an earlier average model to a recently suggested modification and to examine the effect of the gain factor in the current feedback

Dror Kimhi; Sam Ben-Yaakov

1991-01-01

108

Implementation of fuzzy logic controller for DC\\/DC converters using field programmable gate array (FPGA)  

Microsoft Academic Search

The implementation of a FPGA based fuzzy controller for DC\\/DC converters is described in this paper. The fuzzy control developed is evaluated with experimental measurements of the closed loop performance of a buck DC\\/DC converter in respect of the line and load regulation

Rafael Ramos; Xavier Roset; A. Manuel

2000-01-01

109

Paralleling DC–DC Switching Converters by Means of Power Gyrators  

Microsoft Academic Search

In this paper, the problem of paralleling DC-DC switching converters is solved by means of power gyrators. The key element of the parallel connection is a buck converter with input filter acting as a power gyrator of type G with controlled output current, i.e., with its DC output current being proportional to its DC input voltage. electromagnetic interference minimization, current

Angel Cid-Pastor; Luis Martinez-Salamero; Corinne Alonso; Ramon Leyva; Sigmund Singer

2007-01-01

110

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

111

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

112

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

PubMed

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

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

2015-02-01

113

Transformerless dc-to-dc converters with large conversion ratios  

NASA Astrophysics Data System (ADS)

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

Middlebrook, R. D.

1988-10-01

114

Design and implementation of a digital power converter for wind energy conversion  

Microsoft Academic Search

This paper presents the design and implementation of power converter for wind generator. The proposed system consists of a wind generator, a buck converter, a bi-directional dc\\/dc converter and lead-acid battery. The wind generator is the main power source of the system, and the battery is used for energy storage and power compensation. In order to make the wind power

Chih-Chiang Hua; Cheng-Zong He

2011-01-01

115

Low-loss converters with high step-up conversion ratio working at the border between continuous and discontinuous mode  

Microsoft Academic Search

The use of tapped inductors in the classical boost or buck-boost converter leads to a high step-up ratio thus avoiding the extreme duty cycles of the active switch and the high peak currents in the active and passive switches. Two converters are presented and analyzed. Due to the simultaneous regulation of the switching frequency and the duty cycle on one

Felix A. Himmelstoss; P. H. Wurm

2000-01-01

116

A Novel Time-Domain Based Design of PWM Controllers for Switch-Mode Converters and its Implementation by  

E-print Network

to discrete domain transformation and discretization. Digital PID controllers for a Buck and Boost type converters were implemented experimentally on a TMS320LF2407 DSP core. The code for the proposed PID controlA Novel Time-Domain Based Design of PWM Controllers for Switch-Mode Converters and its

117

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

118

Soft switching active snubbers for DC\\/DC converters  

Microsoft Academic Search

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

Ahmed Elasser; D. A. Torrey

1995-01-01

119

Soft switching active snubbers for DC\\/DC converters  

Microsoft Academic Search

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

A. Elasser; D. A. Torrey

1996-01-01

120

"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

121

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

122

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

123

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

124

Dynamic properties of a step-down sinusoidal current AC\\/DC converter under state-feedback control  

Microsoft Academic Search

A control system is presented for a switching AC\\/DC converter which complies with electromagnetic compatibility (EMC) standards on conducted emissions and is suitable for applications presently using line-commutated controlled-rectifiers. The properties of the buck converter (which steps-down from 0.866 Vline(peak)) are compared to those of the established boost converter (which steps-up from Vline(peak)). The reduction in size of the energy

A.-M. Majed; T. C. Green; B. W. Williams

1993-01-01

125

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

Microsoft Academic Search

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

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

2011-01-01

126

Large step-down DC–DC converters with reduced current stress  

Microsoft Academic Search

In this paper, several DC–DC converters with large voltage step-down ratios are introduced. A simple modification in the output section of the conventional buck and quadratic converters can effectively extend the duty-cycle range. Only two additional components (an inductor and diode) are necessary for extending the duty-cycle range. The topologies presented in this paper show an improvement in the duty-cycle

Esam H. Ismail

2009-01-01

127

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

128

Zero-voltage switching technique in dc/dc converters  

NASA Astrophysics Data System (ADS)

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

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

1990-07-01

129

Compensated gain control circuit for buck regulator command charge circuit  

DOEpatents

A buck regulator command charge circuit includes a compensated-gain control signal for compensating for changes in the component values in order to achieve optimal voltage regulation. The compensated-gain control circuit includes an automatic-gain control circuit for generating a variable-gain control signal. The automatic-gain control circuit is formed of a precision rectifier circuit, a filter network, an error amplifier, and an integrator circuit. 5 figs.

Barrett, D.M.

1996-11-05

130

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

131

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

NSDL National Science Digital Library

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

2008-10-06

132

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

E-print Network

Minimum PCB Footprint Point-of-Load DC-DC Converter Realized with Switched-Capacitor Architecture, CA 94703, USA {vwng, mseeman, sanders}@eecs.berkeley.edu Abstract -- This work reports on the design in printed circuit board (PCB) footprint, passive component height and cost when compared to surveyed buck

Sanders, Seth

133

Improving dynamic performance and efficiency of a resonant switched-capacitor converter based on phase-shift control  

Microsoft Academic Search

This paper presents the output voltage regulation characteristics and the dynamic performance of an RSCC using a phase-shift control. The proposed phase-shift control realizes soft switching operation even if the output voltage was changed, and it achieves a higher conversion efficiency. A theoretical analysis shows that the RSCC can reduce its inductor volume compared with a buck converter when its

Kenichiro Sano; Hideaki Fujita

2009-01-01

134

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

Microsoft Academic Search

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

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

2010-01-01

135

Boost-buck push-pull converter for very wide input range single stage power conversion  

Microsoft Academic Search

In many avionics systems, the power supply is required to operate over a very wide input voltage range. In these aircraft systems the power supplies are powered off a permanent magnet generator (PMG). The PMG, which is typically mounted via a gear box to the engine of the aircraft, outputs a voltage proportional to the speed of the engine. It

J. J. Albrecht; J. Young; W. A. Peterson

1995-01-01

136

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

Microsoft Academic Search

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

K. W. R. Chew; L. Siek

2010-01-01

137

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

ERIC Educational Resources Information Center

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

June, Audrey Williams

2009-01-01

138

Magnetorheological converters  

SciTech Connect

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

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

1986-04-01

139

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

140

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

141

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

NSDL National Science Digital Library

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

2008-10-06

142

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

ERIC Educational Resources Information Center

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

Smith, J. David

143

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

144

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

NSDL National Science Digital Library

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

2008-10-06

145

Analysis and implementation of a DC-DC step-down converter for low output-voltage and high output-current applications  

Microsoft Academic Search

A novel DC-DC step-down converter with interleaved control for low output-voltage and high output-current applications is presented in this paper. The voltage gain of the proposed converter is half of the conventional buck converter with reduced current stresses on power devices and low output-current ripple are reduced. The operating principle, steady-state analysis, and small-signal model analysis are discussed in detailed.

Chih-Hsien Hsieh; Tsorng-Juu Liang; Lung-Sheng Yang; Ray-Lee Lin; Kai-Hui Chen

2010-01-01

146

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

147

Performance of a High-Efficiency Switched-Capacitor-Based Resonant Converter With Phase-Shift Control  

Microsoft Academic Search

This paper presents operating performance of a switched-capacitor-based resonant converter (SCRC) using a phase-shift control method. The proposed phase-shift control re- alizes zero-voltage switching operation, and thus achieves a high- conversion efficiency. A theoretical analysis shows that the SCRC can reduce its inductor volume compared with a conventional buck converter when the output voltage range is within 19%-81% of its

Kenichiro Sano; Hideaki Fujita

2011-01-01

148

A high efficiency current mode step-up\\/step-down DC-DC converter with smooth transition  

Microsoft Academic Search

This paper presents a current mode step-up\\/step-down DC-DC converter with small output voltage ripple, high efficiency, and fast transient response. When the input voltage is much higher or lower than the output voltage, the converter operates in peak current pure buck mode or valley current pure boost mode to reduce the switching loss. Double lossless current sense circuits are adopted

Yanzhao Ma; Jun Cheng; Guican Chen

2011-01-01

149

Nunca ha sido fcil distinguir los hechos de la informacin falsa sobre los alimentos; las estrategias de mercadeo, las frases  

E-print Network

Nunca ha sido fácil distinguir los hechos de la información falsa sobre los alimentos; las unos mitos comunes y persistentes respecto a los alimentos: Mito: Las frutas y verduras frescas son más alimentos congelados y enlata- dos son tan nutritivos como los frescos. De hecho, ya que el licopeno es

Burke, Peter

150

Feeding and reproductive behaviour in fallow bucks (Dama dama)  

NASA Astrophysics Data System (ADS)

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

Apollonio, Marco; Vittorio, Irene

2004-12-01

151

On-chip DC-DC converters for three-dimensional ICs  

Microsoft Academic Search

Guidelines for distributing a buck converter rectifier for application to three-dimensional (3-D) circuits is described. The 3-D rectifier exploits the properties of transmission lines to generate and distribute power supplies to different planes. As compared to a conventional rectifier, the proposed rectifier circuit only requires moderately size capacitors without the use of onchip inductors. A case study in a 0.18

Jonathan Rosenfeld; Eby G. Friedman

2009-01-01

152

Analysis of the zero-current-switched quasiresonant converters used as power factor preregulators  

Microsoft Academic Search

The use of zero-current-switched quasi-resonant converters (ZCS-QRCs) as power factor preregulators (PFPs) is studied. The study is applicable to boost, buck-boost, flyback, SEPIC, and Cuk topologies. The main conclusion is that the switching frequency variation range using a half-wave resonant switch is lower than that using a full-wave resonant switch if the load connected to the output is almost constant.

P. Gil; J. Sebastian; J. A. Cobos; J. Uceda; F. Aldana

1992-01-01

153

Using zero-current-switched quasiresonant converters as power factor preregulator  

Microsoft Academic Search

Th use of zero-current-switched quasiresonant power converters (ZCS-QRCs) as power factor preregulators (PFPs) is studied. The study is applicable to boost, buck-boost, flyback, SEPIC, and Cuk topologies. The main conclusion obtained is that the switching frequency variation range using a half-wave resonant switch is lower than that using a full-wave resonant switch if the load connected to the output is

J. Sebastian; J. Uceda; J. A. Cobos; P. Gil

1991-01-01

154

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

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

155

Optimal Switching Control of a Step-Down DC-DC Converter H. Kawashima, Y. Wardi, D. Taylor, and M. Egerstedt  

E-print Network

-mode hybrid systems, re- cently developed by the authors, to voltage-regulation problems in a step-down DC-DCOptimal Switching Control of a Step-Down DC-DC Converter H. Kawashima, Y. Wardi, D. Taylor, and M of a general algorithmic approach, recently developed by the authors, for voltage regulation in a DC-DC buck

Egerstedt, Magnus

156

Power converter  

NASA Technical Reports Server (NTRS)

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

Black, J. M. (inventor)

1981-01-01

157

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

NSDL National Science Digital Library

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

2008-10-06

158

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

NSDL National Science Digital Library

Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>Trial Sterilization is justified The case conluded that Carrie, Emma, and Vivian represented three generations of imbeciles, which justified Carrie's sterilization.

2008-10-06

159

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

NSDL National Science Digital Library

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

2008-10-06

160

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

NSDL National Science Digital Library

Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>epilogue A false analogy In the Supreme Court decision, Justice Holmes compared sterilization for feeblemindedness to a vaccination for smallpox.

2008-10-06

161

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

NSDL National Science Digital Library

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

2008-10-06

162

Interpreted reflection seismic events near the North Central Oil 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. The hole was located about 5 mi southeast of the border fault on the crest of the Revere anticline, a transverse structure that plunges northwestward toward the border fault. This drill hole, No. 1 Cabot-KBI penetrated in descending order 2900 ft of lacustrine red and gray shale (Passaic Formation of Jurassic and Triassic age), 3600 ft of lacustrine gray and black shale (Lockagong Formation of Triassic age), and 4000 ft of fluvial sandstone and red shale (Stockton Formation of Triassic age). Although the drill hole 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 NB-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. This anticline has no surface expression, but, in combination with the intersecting Revere anticline, provides an obvious exploration target. Our interpretation suggests that the No. 1 Cabot-KBI drill hole ends about 1500 ft above the border fault and the underlying middle Proterozoic basement. High-amplitude seismic events from the Stockton Formation on the south-eastern flank of the large anticline may indicate undiscovered gas accumulations.

Ryder, R.T.; Miller, J.J.; Grow, J.A.; Ratcliffe, N.M. (Geological Survey, Reston, VA (United States))

1993-08-01

163

Zero-derivative method of analog controller design applied to step-down DC-DC converters  

Microsoft Academic Search

In this paper, we present new systematic method for the design of an analog PID controller, applied to the voltage-mode step-down (buck) DC\\/DC converters. The method relies on the specification of trajectory of the load transient response. Particularly, we are interested to design a controller limiting the voltage under\\/overshoot to its lowest possible value. It is shown that this lowest

Vratislav Michal; Christophe Premont; Gaël Pillonnet; Nacer Abouchi

2010-01-01

164

76 FR 37143 - Buck Island, Green Cay, and Sandy Point National Wildlife Refuges, U.S. Virgin Islands; Final...  

Federal Register 2010, 2011, 2012, 2013

...40136-1265-0000-S3] Buck Island, Green Cay, and Sandy Point National Wildlife Refuges, U.S...assessment for Buck Island, Green Cay, and Sandy Point National Wildlife Refuges (NWRs...to: Mr. Mike Evans, Refuge Manager, Sandy Point National Wildlife Refuge, 3013...

2011-06-24

165

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

NSDL National Science Digital Library

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

2008-10-06

166

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

167

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. David.

168

1927 Buck vs. Bell trial, Paul LombardoSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>outcome Carrie's sterilization in context. Carrie's one-hour sterilization took place in 1927, the same year that Babe Ruth hit 60 home runs and Charles Lindbergh flew solo across the Atlantic.

2008-10-06

169

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

Microsoft Academic Search

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

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

170

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

E-print Network

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

Bogaerts, Steven

171

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

172

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

Microsoft Academic Search

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

Jia Wei; Fred C. Lee

2005-01-01

173

Measurement: Converting Distances  

NSDL National Science Digital Library

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

2006-01-01

174

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

Microsoft Academic Search

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

Kodjo Agbossou; Sousso Kélouwani; Adil Anouar; Mohanlal Kolhe

2004-01-01

175

The first witness at Buck vs. Bell trial, Paul LombardoSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>trial Arthur Estabrook's testimony Arthur Estabrook, a psychologist for the Eugenics Record office, testified that Carrie, her daughter Vivian, and her mother Emma were all feeblminded.

2008-10-06

176

75 FR 22168 - ADSOUTH PARTNERS, Inc., American Racing Capital, Inc., Buck-A-Roo$ Holding Corporation, DDS...  

Federal Register 2010, 2011, 2012, 2013

...Racing Capital, Inc., Buck-A- Roo$ Holding Corporation, DDS Technologies USA, Inc., and VECTr Systems Inc.; Order of...current and accurate information concerning the securities of DDS Technologies USA, Inc. (CIK: 1099217) because it has...

2010-04-27

177

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

NSDL National Science Digital Library

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

2008-10-06

178

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

179

A fully integrated wide-band PID controller with capacitor-less compensation for step-down DC-DC converter  

Microsoft Academic Search

A fully integrated wide-band PID controller is implemented for a buck DC-DC converter operating in voltage mode. To implement efficiently areal on-chip PID controller, a novel compensator is proposed utilizing AC ripple current of the inductor. The integral controller with an error amplifier and the proportional controller do not require any additional capacitors. The bandwidth of overall loop is about

Hyun-Hee Park; Young-Jin Woo; Gyu-Hyeong Cho

2011-01-01

180

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

NSDL National Science Digital Library

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

2008-10-06

181

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

182

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

183

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

184

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

185

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.

186

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

187

Boost Converters for Gas Electric and Fuel Cell Hybrid Electric Vehicles  

SciTech Connect

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

McKeever, JW

2005-06-16

188

PDF to HTML Converter  

NSDL National Science Digital Library

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

2010-01-01

189

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

190

Spermatogonial stem cells in the testis of an endangered bovid: Indian black buck (Antilope cervicapra L.).  

PubMed

Numerous wild bovids are facing threat of extinction owing to the loss of habitat and various other reasons. Spermatogonial stem cells (SSCs) represent the only germline stem cells in adult body that are capable of self-renewal and that can undergo differentiation to produce haploid germ cells. SSCs can, therefore, serve as a useful resource for preservation of germplasm of threatened and endangered mammals. The Indian black buck (Antilope cervicapra L.) is a small Indian antelope that is listed as endangered by the Indian Wildlife Protection Act, 1972. Immunohistochemical analysis of testes tissues of black buck revealed the presence of spermatogonia that were specifically stained by lectin-Dolichos biflorus agglutinin (DBA). The expression of pluripotent cell-specific markers, NANOG and stage-specific embryonic antigen-1 (SSEA-1), was detected in spermatogonia. Interestingly, the expression of POU5F1 (OCT3/4) was absent from spermatogonia, however, it was detected in differentiating cells such as spermatocytes and round spermatids but not in elongated spermatids. The expression of NANOG protein was also present in spermatocytes but absent in round and elongated spermatids. Using the testis transplantation assay, stem cell potential of black buck spermatogonia was confirmed as indicated by the presence of colonized DBA-stained cells in the basal membrane of seminiferous tubules of xenotransplanted mice testis. The findings from this study suggest the presence of SSCs in the testis of an endangered bovid for the first time and open new possibility to explore the use of SSCs in conservation. PMID:21719218

Goel, Sandeep; Reddy, Niranjan; Mahla, Ranjeet Singh; Suman, Sanjay Kumar; Pawar, Rahul Mohanchandra

2011-07-01

191

Bucking Coil Implementation on PMT for Active Cancelling of Magnetic Field  

SciTech Connect

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

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

2013-11-01

192

Multilevel converters-a new breed of power converters  

Microsoft Academic Search

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

Jih-Sheng Lai; Fang Zheng Peng

1996-01-01

193

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

194

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

195

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

196

Complex brecciation and shock effects in the Buck Mountain Wash (H3-5) chondrite  

NASA Astrophysics Data System (ADS)

Buck Mountain Wash (BMW) is a new genomict breccia (H3-5) found in the Franconia (H5) strewn field in Arizona that shows complex brecciation and shock effects. It contains three distinct chondritic lithologies in sharp contact: a) a main lithology that consists primarily of petrographic type 5 material but which has finely intermixed type 3 and 4 material, b) a shock-blackened (shock stage S5) type 3 lithology (lithology A), and c) a shock-blackened type 3/4 lithology (lithology B). Buck Mountain Wash was lithified after impact-mixing and impact-melting of weakly and strongly metamorphosed materials, possibly at depth in the regolith of the parent body. Shock effects included brecciation on a fine scale, localized impact-melting of silicates, partial melting, and mobilization of metal-sulfide, and chemical fractionations that produced non-H-group composition kamacite by two disequilibrium mechanisms. Shock heating did not cause significant thermal metamorphism in the shock-blackened lithologies of BMW, except possibly in areas adjacent to whole-rock shock melt. During lithification, cooling must have been rapid at high temperatures to preserve glass and inhomogeneous silicate compositions, but not so fast at lower temperatures as to produce dendritic metal-sulfide globules or martensite.

Hutson, Melinda; Ruzicka, Alex; Pugh, Richard; Sloan, Larry; Thompson, Edwin

2007-06-01

197

Nonuniversality of entanglement convertibility  

NASA Astrophysics Data System (ADS)

Recently, it has been suggested that operational properties connected to quantum computation can be alternative indicators of quantum phase transitions. In this work we systematically study these operational properties in one-dimensional systems that present phase transitions of different orders. For this purpose, we evaluate the local convertibility between bipartite ground states. Our results suggest that the operational properties, related to nonanalyticities of the entanglement spectrum, are good detectors of explicit symmetries of the model, but not necessarily of phase transitions. We also show that thermodynamically equivalent phases, such as Luttinger liquids, may display different convertibility properties depending on the underlying microscopic model.

Bragança, Helena; Mascarenhas, Eduardo; Luiz, G. I.; Duarte, C.; Pereira, R. G.; Santos, M. F.; Aguiar, M. C. O.

2014-06-01

198

Fractional Watt AMTEC Converter  

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

199

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.

200

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

PubMed

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

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

2014-12-01

201

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

202

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

203

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

204

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

205

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

206

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.

Elizabeth Stapel

207

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

208

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

209

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.

210

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

211

Unity power factor converter  

NASA Technical Reports Server (NTRS)

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

Wester, Gene W. (Inventor)

1980-01-01

212

Wave energy converter  

SciTech Connect

A power generation system for converting the motion of waves on a body of water such as a lake or sea to drive pumps, electrical generators or the like. A weighted float rides on the waves. A cable and pulley arrangement changes the direction, travel and force of the wave energy action imparted on the float and drives a hydraulic circuit. The hydraulic circuit includes an accumulator for temporary energy storage and release to assist in maintaining constant flow and pressure of hydraulic fluid to one or more hydraulic motors during each wave cycle. The hydraulic motor drives a load such as an electric generator. An automatically actuated device adjusts for high and low tides.

Taylor, R.N.

1984-02-28

213

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

PubMed

Fifteen Boer goat bucks, (6-8 months old), were allocated into two groups and fed ad libitum for a period of 29 days. The WH group (winter hay; n = 8) received a chopped diet consisting of grass hay, predominantly Themeda trianda grass (cut during the winter) from a natural pasture (veld). The WH+S group (winter hay plus supplement; n = 7) received a chopped diet consisting of Themeda trianda veld hay, supplemented with maize meal, molasses meal and urea. Body weights and feed consumption were recorded. Animals were slaughtered and carcass characteristics (weight and percentages of selected carcass cuts) and the carcass chemical composition were determined. The WH+S animals showed a higher live weight and cumulated feed intake. Carcass cuts from WH animals represented a higher percentage of the total carcass, especially cuts where muscle depots are higher (legs, best end chops and prime cuts). There is an attempt by non-supplemented animals to preserve the body's nitrogen reserves under prolonged nutritional stress conditions, and there is consequently a necessity to supplement feeding of small ruminants fed winter veld hay, especially if the animals are to be used in subsequent breeding seasons. PMID:17165615

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

2006-07-01

214

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

215

Ocean wave energy converter  

SciTech Connect

This patent describes apparatus for converting the energy of wave motion on the surface of a body of water to electricity comprising: lower structural support means approximately forming edge elements of an equilateral triangle; lower tube receptacles connected to the lower structural support means approximately forming vertex elements of an equilateral triangle; tubular members having upper and lower portions positioned within the tube receptacles approximately forming trimetric edge elements of a right conical frustum; a separable buoyancy device affixed to the upper portions of the tubular members above the lower structural support means, the buoyancy device having upper and lower surfaces and an enclosed space therein; an annulated receptacle plate affixed to the upper surface of the buoyancy device; truncated right circular cylinders connected to the annulated receptacle plate extending outwardly in coaxial alignment with respective tubular members; articulated brackets connected to the annulated receptacle plate in radial extension; upper structural support means connected to the articulated brackets in radial extension for connection to other receptacle plate articulated brackets of a module array; and dual rolling contact support means comprising open linear slide bearings operatively positioned within the tube upper portions and the truncated cylinders.

Ames, P.F.

1987-06-09

216

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.

217

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

218

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

E-print Network

-Based Auxiliary Energy System for Electric Vehicles Micah Ortúzar, Juan Dixon (SM IEEE) and Jorge Moreno decades. Nevertheless, pure electric vehicles still have not achieved ranges comparable to that of gas in most electric batteries compared to that of gasoline, is resolved in hybrid vehicles by combining high

Catholic University of Chile (Universidad Católica de Chile)

219

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

E-print Network

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

220

CRIME BULLETIN INCIDENT: Catalytic Converter Thefts  

E-print Network

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

Barrett, Jeffrey A.

221

Converting Petroleum Coke to Electricity  

E-print Network

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

Pavone, A.

222

Thermoionic converter for space Reactor  

Microsoft Academic Search

Thermionic converters offer many advantages for use as space reactors. Over the last several years, six experiments were performed, of which four were in-pile experiments and two out-pile experiments. Of the four in-pile experiments, three involved the use of three converters linked in series. The use of nuclear reactors as the power source for an electrical system in space is

Shengquan Cao; Jicai Yang

1990-01-01

223

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

224

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

225

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

ERIC Educational Resources Information Center

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

Ravitz, Jason

2008-01-01

226

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

227

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

228

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

229

Topological constraints on basic PWM converters  

Microsoft Academic Search

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

Kwang-Hwa Liu; F. C. Lee

1988-01-01

230

Integrated magnetic for LLC resonant converter  

Microsoft Academic Search

A new LLC resonant converter is proposed for front end DC\\/DC conversion in a distributed power system. This converter shows some potential benefits in this application. This paper proposes several integrated magnetic designs for LLC resonant converter. This converter has three magnetic components. With magnetic integration, first, a number of components can be reduced; secondly, flux ripple cancellation is achieved

Bo Yang; Rengang Chen; Fred C. Lee

2002-01-01

231

PWM Resonant Single-Switch Isolated Converter  

Microsoft Academic Search

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from a high device stress and a large transformer size. To relieve these drawbacks, a high-efficient pulsewidth modulation resonant single-switch isolated converter is proposed. The proposed converter derives the power using the resonance between transformer leakage inductor

Ki-Bum Park; Chong-Eun Kim; Gun-Woo Moon; Myung-Joong Youn

2009-01-01

232

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

233

Charge-pump voltage converter  

DOEpatents

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

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

2009-11-03

234

A novel interferometric wavelength converter  

Microsoft Academic Search

The fiber Kerr effect employment in a wavelength conversion version, owing to low silica nonlinearity, has been prevented by the lack of an efficient interferometric architecture. A novel all-fiber wavelength converter is presented and characterized. The proposed scheme while taking advantage of the Kerr effect properties in standard communication optical fiber overcomes classical interferometric structure limitations, such as high environmental

Pierpaolo Boffi; Lucia Marazzi; Mario Martinelli

1999-01-01

235

Portable convertible blast effects shield  

DOEpatents

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

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

2011-03-15

236

Reducing catalytic converter pressure loss  

SciTech Connect

This article examines why approximately 30--40% of total exhaust-system pressure loss occurs in the catalytic converter and what can be done to reduce pressure loss. High exhaust-system backpressure is of concern in the design of power trains for passenger cars and trucks because it penalizes fuel economy and limits peak power. Pressure losses occur due to fluid shear and turning during turbulent flow in the converter headers and in entry separation and developing laminar-flow boundary layers within the substrate flow passages. Some of the loss mechanisms are coupled. For example, losses in the inlet header are influenced by the presence of the flow resistance of a downstream substrate. Conversely, the flow maldistribution and pressure loss of the substrate(s) depend on the design of the inlet header.

NONE

1996-06-01

237

Portable convertible blast effects shield  

SciTech Connect

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

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

2010-10-26

238

Portable convertible blast effects shield  

DOEpatents

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

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

2007-05-22

239

Transient of modified HVDC converters  

Microsoft Academic Search

The bridge circuit used in high voltage direct current (HVDC) converters may be modified by including by-pass thyristor valves connected to tapping points on the secondary windings of the transformer to give a reduction in both harmonic generation and reactive volt–ampere absorption for the rectifier and inverter modes of operation.In this paper, control strategies for the transient response of the

Hussein. D. Al-Majali; Sulaiman. M. Al-Dhalaan

2007-01-01

240

Microenergy Converter Using Insect Wings  

Microsoft Academic Search

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

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

241

Green phosphor-converted LED  

Microsoft Academic Search

Green phosphor-converted LEDs using a blue pump InGaN diodes have advantages over the direct green InGaN LED with regards to color stability with drive and\\/or temperature. Added manufacturing steps are outweighed by higher color yield, as a range of pump colors can be used without changing the final chromaticity. The conversion losses can be smaller than the decrease in wall-plug

Regina Mueller-Mach; Gerd O. Mueller; Troy A. Trottier; Michael R. Krames; A. Kim; Dan A. Steigerwald

2002-01-01

242

High efficiency thermionic converter studies  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

243

Large wind energy converter: Growian 3 MW  

NASA Technical Reports Server (NTRS)

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

Koerber, F.; Thiele, H. A.

1979-01-01

244

Light-off behavior of catalytic converters  

Microsoft Academic Search

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

P. S. Hagan; D. W. Schwendeman

1994-01-01

245

COMMUNITY ALERT INCIDENT: Catalytic Converter Thefts  

E-print Network

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

Rose, Michael R.

246

Compact HVDC converter station design considerations  

Microsoft Academic Search

In this paper, the possible means to reduce HVDC converter station land area requirements are shown. The split-up of real estate between the different kinds of equipment in present-day terminals is analysed. From this, a priority list for suitable action to be taken is deducted. Three concepts of converter valves suitable for compact converter stations are briefly discussed. By example

P. Lips

1976-01-01

247

Acoustics of automotive catalytic converter assemblies  

Microsoft Academic Search

In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the

Nolan S. Dickey; Ahmet Selamet; Steve J. Parks; Kevin V. Tallio; Keith D. Miazgowicz; Paul M. Radavich

2003-01-01

248

Tapped-Inductor Buck HB-LED AC–DC Driver Operating in Boundary Conduction Mode for Replacing Incandescent Bulb Lamps  

Microsoft Academic Search

High-brightness light-emitting diodes (HB-LEDs) are recognized as being potential successors of incandescent bulb lamps due to their high luminous efficiency and long lifespan. To achieve these advantages, HB-LED ballast must be durable and efficient. Furthermore, for this specific application, ac–dc HB-LED ballast requires a high-step-down ratio, high power factor and low cost. This paper presents a tapped-inductor buck power factor

Diego G. Lamar; Marcos Fernandez; Manuel Arias; Marta M. Hernando; Javier Sebastian

2012-01-01

249

Tapped-inductor buck HB-LEDs AC-DC driver operating in Boundary Conduction Mode for replacement incandescent bulb lamps  

Microsoft Academic Search

It is known that High-Brightness Light-Emitting Diodes (HB-LEDs) are potential successors of incandescent bulb lamps due to its high luminous efficiency and high lifetime. To realize these advantages the HB-LED ballast must be durable and efficient. Also, for this specific application the ac-dc HB-LEDs ballast needs high-step-down ratio, high Power Factor (PF) and low-cost. This paper presents a tapped-inductor buck

D. G. Lamar; M. Fernandez; C. Toyos; M. M. Hernando; J. Sebastian

2012-01-01

250

A New Control Method of a Resonant Switched-Capacitor Converter and the Application for Balancing of the Split DC Voltages in a Multilevel Inverter  

NASA Astrophysics Data System (ADS)

This paper proposes a new voltage-balancing circuit for the split dc voltages in a diode-clamped five-level inverter. The proposed circuit is based on a resonant switched-capacitor converter (RSCC), which consists of two half-bridge inverters, a resonant inductor and a resonant capacitor. A new phase-shift control of the RSCC is proposed to improve voltage balancing performance. Theoretical analysis reveals the rating of the RSCC and stored energy in the resonant inductor. Experimental results confirm the reduction of the inductor to one tenth in volume as compared to a conventional voltage-balancing circuit based on buck-boost topology. Moreover, the proposed phase-shift control has demonstrated that it is possible to eliminate the voltage deviation between the dc capacitors.

Sano, Kenichiro; Fujita, Hideaki

251

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

252

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

NASA Astrophysics Data System (ADS)

The Saanen is a highly productive breed, and for this reason, it has been raised in Brazil, but mostly under climate conditions completely different from where the breed originated. The objective of this study was to investigate variations in semen parameters and sperm membrane proteins from Saanen bucks (n = 7) raised in Northeastern Brazil, during dry season (September, October, and November) and rainy season (March, April, and May). We showed that during the dry season, sperm motility, concentration, and the percentage of normal sperm decreased as compared to the rainy season. Rectal temperatures of bucks had no significant (p > 0.05) variations during the dry and rainy seasons. However, temperatures of left and right skin testis were higher (p < 0.05) during the dry as compared to the rainy season. Expression of three proteins (lysine-specific demethylase 5D, adenosine triphosphate (ATP) synthase subunit d, and radial spoke head protein 9 homolog) in sperm membrane were more intense in rainy season and only one protein (cytosol aminopeptidase) had greater expression in the dry season of the year. Our results show that mechanisms of testicular thermoregulation of Saanen bucks did not prevent a decrease in seminal parameters during the dry season. This deterioration may be related to reduced expression of proteins associated with important functions in sperm membrane.

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

2014-08-01

253

Switching power converter Figure 1(a): Switching DC-DC converter with analog voltage-mode control  

E-print Network

is based on well-known approaches to discrete-time modeling and the standard Z-transform, takes had a long history of contributions, including [1-6]. Recently, the growing interest in practical presented in [6], which is based on the modified Z- transform, is straightforwardly applicable only to buck

254

Wood stove having catalytic converter  

SciTech Connect

A wood burning stove is formed with double front and rear side walls of heat conductive metal spaced apart by heat conductive spacer fins and providing air passageways by which room air is heated by conduction from the walls which are heated by the burning of wood deposited on a firebox floor supported in heat conducting relationship with the inner side walls. A catalytic converter is disposed over the fire area in the upper portion of the stove, and is arranged to receive preheated fresh secondary air which mixes with hot, incompletely combusted compounds from the fire and, in the presence of the catalyst, induces a secondary combustion of the substances. This mixture is channeled into a heat extraction chamber where the secondary combustion is completed and the resultant heat is transferred to the metal body of the stove. An exhaust passageway is provided for releasing the products of complete combustion into the atmosphere.

Willson, A.C.

1982-12-14

255

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

256

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

257

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

258

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

259

Development of a Modular Power Converter  

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

260

Low Frequency Characterization of PWM Converters  

Microsoft Academic Search

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

Khai D. T. Ngo

1986-01-01

261

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

262

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

263

Novel multi-element resonant converters for front-end dc\\/dc converters  

Microsoft Academic Search

This paper proposes novel multi-element resonant converters for front-end dc\\/dc converters. The superior performance of the proposed resonant converters is to provide inherent current protection and very low circulating energy. With the optimized design, the proposed resonant converters can operate under short output circuit. Based on the third order harmonic injection, the circulating energy of the resonant tank can be

Dianbo Fu; Fred C. Lee; Ya Liu; Ming Xu

2008-01-01

264

A direct AC\\/AC converter based on current-source converter modules  

Microsoft Academic Search

The research on direct AC\\/AC conversion in the past twenty years has been following two major directions: improving the performance of the original nine-bidirectional-switch matrix converter topology; and using converter topologies composed of unidirectional switches only. In this paper, a direct AC\\/AC converter topology based on current-source converter modules is proposed. It is shown, through analysis and simulation, that the

Mehrdad Kazerani

2003-01-01

265

Celilo Converter Station mercury arc valve replacement  

Microsoft Academic Search

The Pacific HVDC Intertie (PDCI) is the most complicated HVDC Scheme in the world. Decisions about changing the PDCI are further complicated by a complex ownership arrangement. The Intertie has the a capacity of 3100 MW and runs from the Celilo Converter Station in The Dalles, Oregon to the Sylmar Converter Station in Sylmar, California. After an earthquake damaged the

Wayne Litzenberger

2002-01-01

266

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

267

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

268

RF digital-to-analog converter  

DOEpatents

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

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

1995-01-01

269

Directivity of parametric converters with biharmonic pumping  

Microsoft Academic Search

The conditions of stable amplification and ideal directivity of amplification are obtained for different types of three-frequency parametric converters with biharmonic pumping. The equivalent circuit of the converter incorporates a parametric diode whose elastance varies time-dependently under the action of voltages from two pumping sources and an oscillatory system containing resonant chains for three different working frequencies. A system of

Iu. K. Tarabrin

1976-01-01

270

Efficient polarization converter for projection displays  

E-print Network

Efficient polarization converter for projection displays W. C. Yip, H. C. Huang, and H. S. Kwok In the waveguiding limit, a twisted nematic liquid crystal cell behaves as an achromatic polarization rotator. We propose and demonstrate the application of such a polarization rotator to convert unpolar- ized light

271

Firing angle optimisation for chain cell converters  

Microsoft Academic Search

Firing angles for chain cell multi-level converters can be optimised to reduce waveform distortion. Optimisation techniques have previously been developed that calculate the required firing angles, but these techniques fall short of accurate optimisation due to over-simplification of the problem. Established optimisation routines often only work on a subset of possible converter modes, hence optimal solutions are not produced for

D. W. Sandells; T. C. Green

2001-01-01

272

Generation of Triggering Signals for Multilevel Converter  

Microsoft Academic Search

Multilevel converter has become attractive in the power industries and it can be applied in many applications especially on improvement of the power quality. This paper presents the generation of triggering signals used to control the cascaded H-bridge (CHB) multilevel converter. One of the carrier based pulse width modulation scheme which is level shifted multicarrier modulation has been chosen to

S. A. Bashi; N. F. Mailah; M. Z. Kadir; K. H. Leong

273

Optimal design methodology for LLC resonant converter  

Microsoft Academic Search

Although LLC resonant converter can achieve wide operation range with high efficiency, lack of design methodology makes it difficult to be implemented. In this paper, based on the theoretical analysis on the operation principles during normal condition and holdup time, the relationship between converter efficiency and operation range with different circuit parameters has be revealed. An optimal design methodology has

Bing Lu; Wenduo Liu; Yan Liang; Fred C. Lee; Jacobus D. van Wyk

2006-01-01

274

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

275

Time interleaved counter analog to digital converters   

E-print Network

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

Danesh, Seyed Amir Ali

2011-11-22

276

Component technology for Stirling power converters  

Microsoft Academic Search

NASA Lewis Research Center has organized a component technology program as part of the efforts to develop Stirling converter technology for space power applications. The Stirling Space Power Program is part of the NASA High Capacity Power Project of the Civil Space Technology Initiative (CSTI). NASA Lewis is also providing technical management for the DOE\\/Sandia program to develop Stirling converters

Lanny G. Thieme

1991-01-01

277

Evaluations of uranium-nitride fueled converters.  

NASA Technical Reports Server (NTRS)

Evaluation of two uranium-nitride (UN) fueled converters was initiated at the Jet Propulsion Laboratory to investigate the effect of fuel on the converter performance while being operated out-of-core. The initial tests were performed with the dynamic data acquisition system that was developed at the Laboratory. Parametric tests of these converters were to obtain: (1) static volt-ampere curves, (2) dynamic volt-ampere curves, and (3) the electrode work functions. The power outputs were 9.3 W/sq cm for the rhenium converter and 3.8 W/sq cm for the tungsten converter at 0.6 V when the emitter surface temperature was 2000 K, according to the static volt-ampere curves.

Shimada, K.; Cassell, P. L.

1971-01-01

278

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

E-print Network

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

Nancy M. Bunker

2005-01-01

279

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

280

Acoustics of automotive catalytic converter assemblies  

NASA Astrophysics Data System (ADS)

In an automotive exhaust system, the purpose of the catalytic converter is to reduce pollutant emissions. However, catalytic converters also affect the engine and exhaust system breathing characteristics; they increase backpressure, affect exhaust system acoustic characteristics, and contribute to exhaust manifold tuning. Thus, radiated sound models should include catalytic converters since they can affect both the source characteristics and the exhaust system acoustic behavior. A typical catalytic converter assembly employs a ceramic substrate to carry the catalytically active noble metals. The substrate has numerous parallel tubes and is mounted in a housing with swelling mat or wire mesh around its periphery. Seals at the ends of the substrate can be used to help force flow through the substrate and/or protect the mat material. Typically, catalytic converter studies only consider sound propagation in the small capillary tubes of the substrate. Investigations of the acoustic characteristics of entire catalytic converter assemblies (housing, substrate, seals, and mat) do not appear to be available. This work experimentally investigates the acoustic behavior of catalytic converter assemblies and the contributions of the separate components to sound attenuation. Experimental findings are interpreted with respect to available techniques for modeling sound propagation in ceramic substrates.

Dickey, Nolan S.; Selamet, Ahmet; Parks, Steve J.; Tallio, Kevin V.; Miazgowicz, Keith D.; Radavich, Paul M.

2003-10-01

281

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

282

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

283

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

284

Waveguide mode converter and method using same  

DOEpatents

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

Moeller, Charles P. (Del Mar, CA)

1990-01-01

285

Converting a Motorcycle to Electric Power  

E-print Network

Research was conducted to determine how simple and practical it would be to convert a standard gasoline powered motorcycle to electric power. The research involved background investigation of useful concepts in electric powered motorcycles...

Simcoe, Christopher M.

2009-12-18

286

Improvements in solid state radiographic converter screens.  

NASA Technical Reports Server (NTRS)

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

Szepesi, Z.

1972-01-01

287

Intermediate-Frequency-to-Video-Band Converter  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

288

Extended modelling for time-encoding converters  

Microsoft Academic Search

Amplitude-quantized time-encoding is beneficial in terms of Shannon capacity, a.o. for data converters. In case of asynchronous, it can be used too for power converters and amplifiers, with extra advantages in terms of power efficiency, power control, in-band quantizer distortion, and absence of both clock-induced noise and power dissipation. This paper fills in the lack of analysis and synthesis tools,

Arthur H. M. van Roermund; Foad Arfaei Malekzadeh; Mehdi Sarkeshi; Reza Mahmoudi

2010-01-01

289

Designing LLC resonant converters for optimum efficiency  

Microsoft Academic Search

This paper presents a novel design methodology for the tank circuit of LLC resonant converters, based on a simplified yet accurate model of the steady-state operation in the ldquobelow-resonancerdquo region. This model is used in a design strategy that aims to design a converter capable of operating with soft-switching in the specified input voltage range, with a load varying from

C. Adragna; S. De Simone; C. Spini

2009-01-01

290

Multiloop control for quasi-resonant converters  

Microsoft Academic Search

A multiloop control scheme for quasi-resonant converters (QRCs) is described. Like current-mode control for pulse width modulation (PWM) converters, this control offers excellent transient response and replaces the voltage-controlled oscillator (VCO) with a simple comparator. In this method, referred to as current-sense frequency modulation (CSFM), a signal proportional to the output-inductor current is compared with an error voltage signal to

Raymond B. Ridley; Wojciech A. Tabisz; Fred C. Y. Lee; V. Vorperian

1991-01-01

291

Harmonically Pumped Stripline Down-Converter  

Microsoft Academic Search

A novel thin-film down-converter which is pumped at a submultiple of the local-oscillator frequency has given a conversion loss which is comparable to the performance of conventional balanced mixers. The converter consists of two stripline filters and two Schottky-barrier diodes which are shunt mounted in a strip transmission line. The conversion loss measured at a signal frequency of 3.5 GHz

MARTIN V. SCHNEIDER; W. W. Snell Jr.

1975-01-01

292

Multilevel converters for large electric drives  

Microsoft Academic Search

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

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

1999-01-01

293

SP100 thermoelectric converter technology development  

Microsoft Academic Search

The SP-100 thermoelectric power converter utilizes reactor-delivered heat and transforms it into usable electric power by purely static means. The converter features conduction coupling of TE cells to both the heat source and the heat rejection elements. The conduction coupling technique offers significant improvement in the system specific power since it avoids the losses associated with parasitic Delta(T)s across the

D. N. Matteo; J. A. Bond; R. J. Rosko

1992-01-01

294

An Isolated DC\\/DC Converter Using High-Frequency Unregulated $LLC$ Resonant Converter for Fuel Cell Applications  

Microsoft Academic Search

This paper suggests an isolated dc\\/dc converter using an unregulated LLC converter for fuel cell applications. The LLC converter operates as an isolated voltage amplifier with a constant voltage gain, and a nonisolated converter installed in the input stage regulates the output voltage under a wide variation of fuel cell stack voltage. By separating the functions, the unregulated LLC converter

Jun-Young Lee; Yu-Seok Jeong; Byung-Moon Han

2011-01-01

295

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

296

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

USGS Publications Warehouse

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

Nutt, Constance J.

2000-01-01

297

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

298

Materials technology for Stirling space power converters  

NASA Technical Reports Server (NTRS)

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

Baggenstoss, William; Mittendorf, Donald

1992-01-01

299

Ac-dc converter firing error detection  

SciTech Connect

Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal.

Gould, O.L.

1996-07-15

300

Bucking Conventional Wisdom  

ERIC Educational Resources Information Center

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

Brady, Marion

2006-01-01

301

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

302

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?

303

Design of high power density DC Bus Converter based on LLC resonant converter with synchronous rectifier  

Microsoft Academic Search

The LLC resonant converter can easily achieve soft-switching and magnetic components integration that makes it an excellent candidate for DC bus converter. In low voltage high output current applications, the design of synchronous rectifier (SR) and transformer is the key issue. A SR driving scheme with less circuit complexity is adopted for switching frequency at the resonant frequency in this

Niu Huapeng; Pei Yunqing; Yang Xu; Wang Laili; Wang Zhaoan

2009-01-01

304

Potential converter for laser-power beaming  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

305

Solar energy converter using surface plasma waves  

NASA Technical Reports Server (NTRS)

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

Anderson, L. M. (inventor)

1984-01-01

306

Quasi-resonant converters - Topologies and characteristics  

NASA Astrophysics Data System (ADS)

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

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

1987-01-01

307

Combination solar photovoltaic heat engine energy converter  

NASA Technical Reports Server (NTRS)

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.

1987-01-01

308

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

309

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

USGS Publications Warehouse

In the 1970s and 1980s elkhorn coral, Acropora palmata, declined dramatically throughout the Caribbean primarily due to white-band disease (WBD). In 2005, elkhorn coral was proposed for listing as threatened under the US Endangered Species Act. WBD was first documented at Buck Island Reef National Monument (BIRNM). Together with hurricanes WBD reduced live elkhorn coral coverage by probably over 90%. In the past decade some recovery has been observed at BIRNM. This study assessed the distribution and abundance of elkhorn coral and estimated the prevalence of WBD at the monument. Within an area of 795 ha, we estimated 97,232-134,371 (95% confidence limits) elkhorn coral colonies with any dimension of connected live tissue greater than one meter, about 3% of which were infected by WBD. Despite some recovery, the elkhorn coral density remains low and WBD may continue to present a threat to the elkhorn coral population. ?? Springer-Verlag 2006.

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

2006-01-01

310

Balancing and harmonic analysis of flying capacitor multilevel converters  

Microsoft Academic Search

To supply medium-voltage AC machines, DC-AC converters working with a high bus voltage are required. By using multilevel converters, these high voltages can be supplied without the need for switches with a high voltage rating. Moreover, the output voltage waveform can be improved considerably. The flying capacitor multilevel converter is a recently developed converter topology assuring a flexible control and

Steven Thielemans; Thomas Vyncke; Jan Melkebeek

2008-01-01

311

Efficient HVDC converter model for real time transients simulation  

Microsoft Academic Search

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

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

1999-01-01

312

Active Harmonic Elimination in Multilevel Converters Using FPGA Control  

E-print Network

for cascaded H-bridges multilevel converter control with unequal DC sources. First, the multilevel converter H- bridge multilevel converter with a real-time controller based on Altera FLEX 10K fieldActive Harmonic Elimination in Multilevel Converters Using FPGA Control Zhong Du, Leon M. Tolbert

Tolbert, Leon M.

313

SINGLE STAGE GRID CONVERTERS FOR BATTERY ENERGY STORAGE  

E-print Network

are switched. The first two topologies were introduced by Baker in 1975 the Cascaded H-Bridge (CHB) converter@iet.aau.dk Keywords: BESS, multilevel converters, medium voltage. Abstract Integration of renewable energy systems, the multilevel converters are the key technology. Multilevel converters represent a smart way to connect power

Munk-Nielsen, Stig

314

1MHz High Efficiency LLC Resonant Converters with Synchronous Rectifier  

Microsoft Academic Search

This paper proposes a novel synchronous rectifier driving scheme for resonant converters. An LLC resonant converter with proposed synchronous rectification is designed and analyzed. It is a high efficiency, high power density solution for future frond end converters. Hold up time extension capability is achieved for designed LLC resonant converter without sacrificing the efficiency for nominal condition. 1kW, 1MHz LLC

Dianbo Fu; Bing Lu; Fred C. Lee

2007-01-01

315

Design and implementation of LLC resonant half bridge converter  

Microsoft Academic Search

LLC resonant converter is proposed for Front End DC\\/DC conversion application. Three advantages are achieved with this resonant converter. First, ZVS turn on and low current turn off of MOSFETs is achieved. The switching loss is reduced so we can operate the converter at higher switching frequency. Second advantage is that with this topology, we can optimize the converter at

L. Sahaya Senthamil; P. Ponvasanth; V. Rajasekaran

2012-01-01

316

Analysis and Design of LLC Resonant Converter with Integrated Transformer  

Microsoft Academic Search

LLC resonant converter has a lot of advantages over the conventional series resonant converter and parallel resonant converter; narrow frequency variation over wide load and input variation, Zero Voltage Switching (ZVS) for entire load range and integration of magnetic components. This paper presents analysis and design consideration for half-bridge LLC resonant converter with integrated transformer. Using the fundamental approximation, the

Hangseok Choi

2007-01-01

317

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,

318

Catalytic Converters Maintain Air Quality in Mines  

NASA Technical Reports Server (NTRS)

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

2014-01-01

319

NEW TECHNOLOGIES IN HVDC CONVERTER DESIGN  

Microsoft Academic Search

1. SUMMARY HVDC technology took a big step forward around 20 years ago when thyristor valves succeeded the mercury arc valves previously used. The converter station concept introduced at that time, however, has remained practically unchanged since then. The time has now come for a further major advance in technology. The introduction of new concepts will change whole approach to

Alf Persson; Lennart Carlsson

320

Converting neutron stars into strange stars  

NASA Technical Reports Server (NTRS)

If strange matter is formed in the interior of a neutron star, it will convert the entire neutron star into a strange star. The proposed mechanisms are reviewed for strange matter seeding and the possible strange matter contamination of neutron star progenitors. The conversion process that follows seeding and the recent calculations of the conversion timescale are discussed.

Olinto, A. V.

1991-01-01

321

Hybrid switch for resonant power converters  

DOEpatents

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

Lai, Jih-Sheng; Yu, Wensong

2014-09-09

322

STIFF: Converting Scientific FITS Images to TIFF  

NASA Astrophysics Data System (ADS)

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

Bertin, Emmanuel

2011-10-01

323

Comparison of multilevel converter-based STATCOMs  

Microsoft Academic Search

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

J. H. Vivas; G. Bergna; M. Boyra

2011-01-01

324

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

325

Integrated multilevel converter and battery management  

Microsoft Academic Search

A cascaded H-bridge multilevel converter is proposed as a BLDC drive incorporating real-time battery management. Intelligent H-bridges are used to monitor battery cells whilst simultaneously increasing their performance by reducing the variation between cells and controlling their discharge profiles.

K. Wilkie; D. Stone; C. Bingham; M. Foster

2008-01-01

326

Resonant switched capacitor converter with high efficiency  

Microsoft Academic Search

Conventional switched capacitor converters have an inherent drawback that their efficiency is much decreased as the output current is increased. This inherent drawback is due to a periodical forced charging and discharging operation in the internal switched capacitors accompanied by a large capacitor current, so that their efficiency can not be increased by decreasing its internal resistance. As a result,

M. Shoyama; T. Naka; T. Ninomiya

2004-01-01

327

Complex Behavior in Switching Power Converters  

E-print Network

and it often turns out that a partic- ular circuit topology or system implementation has found widespread power electronics systems. Our inten- tion is to provide an overview of the recent research effortComplex Behavior in Switching Power Converters CHI K. TSE, SENIOR MEMBER, IEEE, AND MARIO DI

Tse, Chi K. "Michael"

328

Dense Spray Cooled DC-DC Converter  

Microsoft Academic Search

Advances in system packaging are driving densities to unprecedented levels. The increasing densities are creating significant thermal management challenges. In addition, the military is operating under conditions that are pushing operating temperatures to much higher levels. This combination of events is pushing the military to adopt more aggressive liquid-cooling technologies. The authors have demonstrated a dense DC-DC power converter for

Tahir Cader; Ben Tolman; C. Kabrell; D. Olsen

2006-01-01

329

Common mode model of matrix converter  

Microsoft Academic Search

This paper deals with the validation of an EMI model to predict electromagnetic interferences (EMI) produced by direct AC\\/AC matrix converters (MC). The method is based on obtaining a high frequency equivalent circuit, using a combined time and frequency domain approach based on: \\

Jordi Espina; Josep Balcells; Carlos Ortega; Antoni Arias; Liliana de Lillo; Lee Empringham

2011-01-01

330

Assay for Angiotensin-Converting Enzyme.  

ERIC Educational Resources Information Center

Describes a three-hour experiment designed to introduce students to chemistry of the angiotensis-converting enzyme, illustrate design of a quenched fluorescence substrate, and examine considerations necessary in designing a clinical assay. Includes background information on the biochemistry of hypertension, reagents/materials needed, procedures…

Russo, Salvatore F.

1983-01-01

331

All-fiber Kerr wavelength converter  

Microsoft Academic Search

The authors present a novel fibre wavelength converter architecture based on the joint use of Kerr phase modulation and interferometric conversion where drawbacks are greatly reduced. The proposed interferometric architecture maintains all the advantages of the Kerr effect band phase modulation in fiber while assuring a very low operation noise

L. Marazzi; P. Boffi; M. Martinelli

1998-01-01

332

Lathe converted for grinding aspheric surfaces  

NASA Technical Reports Server (NTRS)

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

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

1964-01-01

333

Performance Results of the Stirling Power Converter  

Microsoft Academic Search

The National Aeronautics and Space Administration (NASA) - Lewis Research Center has the responsibility to develop power technologies that have the potential of satisfying anticipated future space mission power requirements. The Free-Piston Stirling Power Converter (FPSPC) is one of the power technologies being evaluated and developed by NASA. FPSPC's have the potential to provide high reliability, long life, efficient operation,

George R. Dochat; James E. Dudenhoefer

1994-01-01

334

A unified analysis of converters with resonant switches  

Microsoft Academic Search

Quasiresonant converters are single-switch resonant converters featuring zero-current or zero-voltage switching. Understanding of the topological structure uniting these converters and the PWM converters on which they are based is used as the basis of general models of their dc and low-frequency ac behavior. An expression is derived that yields the dc conversion ratio of a quasiresonant converter in terms of

Steve Freeland; R. D. Middlebrook

1987-01-01

335

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

336

Component technology for Stirling power converters  

NASA Technical Reports Server (NTRS)

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

Thieme, Lanny G.

1991-01-01

337

Analog current mode analog/digital converter  

NASA Technical Reports Server (NTRS)

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

Hadidi, Khayrollah (Inventor)

1996-01-01

338

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

339

50 MHz Voltage-to-Frequency Converter  

NASA Astrophysics Data System (ADS)

The Voltage-to-Frequency Converter (V2F) is an instrument commonly used in synchrotron beam line experiments for converting a slowly varying voltage signal representing x-ray flux to a high frequency pulse train, with each pulse representing a packet of x-ray energy. The pulses are commonly integrated with a digital counter to calculate total x-ray energy incident on a sample during an exposure. As x-ray experiment data is taken faster and faster and exposure times shrink, V2F frequencies must necessarily increase to preserve precision in measuring total x-ray energy. The APS Detector Group have designed and built two custom 50MHz V2F instruments for APS beam line experiments. The instruments are designed according to the Nuclear Instrument Module (NIM) standard and respectively reside at APS Sector 12-BM, and in the APS Detector Pool [1].

Madden, T.; Baldwin, J.

2014-03-01

340

Optical analog-to-digital converter  

DOEpatents

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

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

2009-07-21

341

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

342

TF34 Convertible Engine System Technology Program  

NASA Technical Reports Server (NTRS)

The ability of the helicopter to function efficiently at zero flight speed is counterbalanced by a limitation to rather low forward flight speeds. An ability to fly efficiently at high speed would provide very significant improvements in rotorcraft productivity and economics. The implementation of such improvements would require the development of a suitable integrated power plant for both the vertical and horizontal flight modes. The engine should be a shaft output engine in the vertical flight mode. In the horizontal mode, the propulsor can be fan or propeller. A description is presented of a program concerned with the demonstration of a convertible turbofan/turboshaft engine. The program is nominally directed toward the demonstration of a propulsion system for an X-wing aircraft. However, the principles being investigated are applicable to any convertible turbofan/turboshaft engine application. At the current early stage of the program, no barrier problems have become apparent, and interesting possibilities for high speed rotorcraft flight are envisaged.

Abdalla, K. L.; Brooks, A.

1982-01-01

343

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

344

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

345

Converted-wave seismic exploration: applications  

Microsoft Academic Search

Converted seismic waves (P-to-S on reflection) are being increasingly used to explore for subsurface targets. Rapid advancements in multicomponent acquisition methods and processing techniques have led to numerous applications for P-S images. Uses that have arisen include sand\\/shale differentiation, carbonate identification, definition of interfaces with low P-wave contrast, anisotropy analysis, imaging through gas zones, shallow high-resolution imaging, and reservoir monitoring.

Robert R. Stewart; James E. Gaiser; R. James Brown; Don C. Lawton

2000-01-01

346

Optically sampled analog-to-digital converters  

Microsoft Academic Search

Optically sampled analog-to-digital converters (ADCs) combine optical sampling with electronic quantization to enhance the performance of electronic ADCs. In this paper, we review the prior and current work in this field, and then describe our efforts to develop and extend the bandwidth of a linearized sampling technique referred to as phase-encoded optical sampling. The technique uses a dual-output electrooptic sampling

Paul W. Juodawlkis; Jonathan C. Twichell; Gary E. Betts; Jeffrey J. Hargreaves; Richard D. Younger; Jeffrey L. Wasserman; F. J. O'Donnell; K. G. Ray; R. C. Williamson

2001-01-01

347

Spectral converters and luminescent solar concentrators  

E-print Network

In this paper we present a comprehensive theoretical description of molecular spectral converters in the specific context of Luminescent Solar Concentrators (LSCs). The theoretical model is an extension to a three-level system interacting with a solar radiation bath of the standard quantum theory of atomic radiative processes. We derive the equilibrium equations of the conversion process and provide specific examples of application of this principle to the development of solar concentration devices.

Petra F. Scudo; Luigi Abbondanza; Roberto Fusco

2009-07-21

348

Converting Frequency Responses to Daily Frequency  

Cancer.gov

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

349

Design of a New Wide Bandwidth TE01-Mode Converter  

NASA Astrophysics Data System (ADS)

This study presents the design and cold testing of a Q-band TE01-mode converter. Integrating Marie transducer and the design of Ching-Fang Yu and Tsun-Hsu Chang, we have improved the design of circular TE01-mode converter. The working principle of each section are analyzed and discussed. Two identical converters are joined back-to-back to explore the field symmetry and to examine the existence of competing modes. The angle-independent transmissions manifest high mode purity. This converter features high back-to-back converting efficiency, high mode purity, compact converting section , and broad bandwidth (18% at a 1-dB transmission).

Wang, Yongshuai; Cai, Zhongbin; Kang, Xiaoke; Liu, Yueling

2011-11-01

350

Thermionic converter performance with oxide collectors  

NASA Technical Reports Server (NTRS)

Thermionic converters using a variety of metal oxide collector surfaces have been fabricated and tested. Both work function and power output data are presented and evaluated. Oxides of barium, strontium, zinc, tungsten and titanium have been incorporated into a variable spacing converter. Tungsten oxide was found to give the highest converter performance and to furnish oxygen for the emitter at the same time. Oxygenated emitters operate at reduced cesium pressure with an increase in electrode spacing. Electron spectroscopy for chemical analysis (ESCA) performed on several tungsten oxide collectors showed cesium penetration of the oxide layer, possibly forming a cesium tungstate bronze. Titanium oxide showed high performance but did not furnish oxygen for the emitter; strontium oxide, in the form of a sprayed layer, appeared to dissociate in the presence of cesium. Sprayed coatings of barium and zinc oxides produced collector work functions of about 1.3 eV, but had excessive series resistance. Lanthanum hexaboride, in combination with oxygen introduced through a silver tube, and cesium produced a low work function collector and better than average performance.

Lieb, D.; Goodale, D.; Briere, T.; Balestra, C.

1977-01-01

351

Modulation and control of matrix converter for aerospace application  

NASA Astrophysics Data System (ADS)

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

Kobravi, Keyhan

352

A low-power reconfigurable analog-to-digital converter  

E-print Network

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

Gulati, Kush

2001-01-01

353

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

1994-01-01

354

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2010 CFR

...Convertibility of military payment certificates. 538.4 Section 538.4 National...CLAIMS AND ACCOUNTS MILITARY PAYMENT CERTIFICATES § 538.4 Convertibility of military payment certificates. (a) For authorized...

2010-07-01

355

78 FR 40132 - Wave Energy Converter Prize Administration Webinar  

Federal Register 2010, 2011, 2012, 2013

...entities with experience in testing wave energy converters in tank test facilities...administering technical competitions. Wave Energy Converter Prize Background...potential for success in the actual open-ocean wave energy harvesting environment....

2013-07-03

356

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

357

32 CFR 538.4 - Convertibility of military payment certificates.  

Code of Federal Regulations, 2011 CFR

...Convertibility of military payment certificates...For authorized personnel. Authorized personnel having in their possession military payment certificates...areas to convert military payment certificates for authorized personnel returning...

2011-07-01

358

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

359

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

360

7 CFR 12.32 - Converted wetland identification criteria.  

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

2014-01-01

361

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

362

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

363

Simulation studies of the three-phase inverse dual converter  

E-print Network

Watson (Member) Supramaniam Srinivasan (Member) J. . Howze (Head of Department) August 1991 ABSTRACT Simulation Studies of the Three-phase Inverse Dual Converter. (August 1991) Jayanthi Arvind, B. E. , Bangalore University; M. S. , Bowling... patience, help and support throughout my research effort. TABLE OF CONTENTS CHAPTER Page I INTRODUCTION . A. DC ? DC Converters B. Previous Research in High-power DC - DC Converters. . . C. Previous Research in Inverse Dual Converter. . . D. Research...

Arvind, Jayanthi

2012-06-07

364

Hierarchical Control of Bridge-of-Bridge Multilevel Power Converters  

Microsoft Academic Search

Multilevel converters are among the members of the family of power-converter topologies for realizing higher power levels and better waveform quality. In addition to the established topologies of neutral-point-clamped three-level and cascaded H-bridge converters, novel topologies that offer attractive features, such as ease of modularity and functionality, continue to be introduced. Among these, the bridge-of-bridge multilevel converters have the potential

Dan C. Ludois; Justin K. Reed; Giri Venkataramanan

2010-01-01

365

Improvement performance of step-down converter through intelligent controllers  

Microsoft Academic Search

In this paper, several different control methods based on intelligent system on DC-DC converter are compared with together. These DC-DC converters are used for the stabilization or the control of DC voltage of a battery. Lately, improvement the performance of the step-down converter is one of the goals of the engineers in the industries. In this paper controlled step-down converter

M. R. Yousefi; M. Bayati Poudeh; S. Eshtehardiha

2008-01-01

366

A monolithic CMOS step-down DC-DC converter  

Microsoft Academic Search

A monolithic CMOS switch-mode step-down power converter, with on-chip PWM technique, has been designed and implemented. Also, a micropower bandgap reference generator is developed for the dc-dc converter. This power converter occupied a chip area of 880times1040 mum2 is fabricated in a 2P4M 0.35-mum CMOS process. The simulation results show that the converter is well regulated over an output range

Yeong-Tsair Lin; Wen-Yaw Chung; Dong-Shiu Wu; Hung-Chan Wang; Hung-Yih Lin; Jiann-Jong Chen

2005-01-01

367

Novel zero-current-switching PWM step down Sepic converter  

Microsoft Academic Search

This paper presents a new step down PWM (pulse width modulation) Sepic (single ended primary inductance converter) converter, featuring soft commutation at zero-current (ZCS), using IGBTs (insulated gate bipolar transistors) as the power switches. This new ZCS-PWM cell provides conditions to obtain a new family of isolated converters. The new ZCS-PWM Sepic converter is used to provide output voltage lower

Lourival T. S. Sobrinho; Roger A. Kitamura; C. A. Canesin

1998-01-01

368

New transformerless, scalable Modular Multilevel Converters for HVDC-transmission  

Microsoft Academic Search

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

Silke Allebrod; Roman Hamerski; Rainer Marquardt

2008-01-01

369

High energy-efficient and compact AC-AC converters  

Microsoft Academic Search

AC-AC converters offer much better energy efficiency than conventional two-stage power converters or inverters. This paper reports a new modular phase bank design approach of AC-AC converters that significantly reduces the size and weight of the power converter and improves the power density. The modular approach and integrated AC power modules offer a much improved design for the power circuits

Jie Chang; T. Sun; Anhua Wang

2001-01-01

370

A fuzzy controller for DC-DC converters  

Microsoft Academic Search

A controller for DC-DC converters based on fuzzy logic is proposed. Being free of complex equations and heavy computation, the controller is expected to control converters that operate at high frequencies. This paper presents the derivation of fuzzy control rules for the basic converter circuits and simulations of the performance of the closed-loop converters in respect of start-up transient, load

W. C. So; C. K. Tse; Y. S. Lee

1994-01-01

371

Optimization of a Multi-Target Voltages Switched Capacitor Converter  

E-print Network

Optimization of a Multi-Target Voltages Switched Capacitor Converter Natan Krihely, Sam Ben--In this paper, an efficient voltage scalable switched capacitor converter (SCC) for 1.1V battery-powered system dissipation in ultra low power systems, the DC-DC converter needs to supply variable sub- threshold load

372

An integrated flyback converter for DC uninterruptible power supply  

Microsoft Academic Search

An integrated flyback power converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SMPS) is presented. This power converter has a high voltage main power input and a low voltage backup battery input. DC output is obtained from the main input via a flyback power converter during normal operation and from the backup battery via

Kwok-Wai Ma; Yim-Shu Lee

1996-01-01

373

Phase controlled dc-ac converter with high frequency switching  

NASA Astrophysics Data System (ADS)

A sinusoidal dc-ac converter is presented in which a pair of switches is placed on each side of the primary and secondary of the isolation transformer. This converter is controlled by the phase difference between the two pairs of switches. The transformer is miniaturized by making the switching frequency high. This converter is especially suitable for small uninterruptible power supply systems.

Harada, Koosuke; Sakamoto, Hiroshi; Shoyama, Masahito

374

An integrated flyback converter for DC uninterruptible power supply  

Microsoft Academic Search

An integrated flyback power converter performing the combined functions of uninterruptible power supply (UPS) and switch-mode power supply (SMPS) is presented. This power converter has a high voltage main power input and a low voltage backup battery input. DC output is obtained from the main input via a flyback power converter during normal operation, and from the backup battery via

Kwok-Wai Ma; Yim-Shu Lee

1994-01-01

375

Life cycle assessment of a catalytic converter for passenger cars  

Microsoft Academic Search

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

Wathanyu Amatayakul; Olle Ramnäs

2001-01-01

376

A high precision resolver-to-DC converter  

Microsoft Academic Search

A newly developed resolver converter, providing a pseudolinear voltage proportional to the shaft angle, is presented. This converter is based on a new concept involving the absolute values of the demodulated sine and cosine resolver signals together with a dedicated linearization technique. The converter enables instantaneous determination of the mechanical angle with a theoretical error of nonlinearity below 0.011° over

Mohieddine Benammar; Lazhar Ben-Brahim; Mohd A. Alhamadi

2005-01-01

377

New transfer function model for PWM power converter  

Microsoft Academic Search

An equivalent circuit for a power converter bridge leg is derived. In this circuit model the PWM (pulsewidth modulation) power switches are represented by dependent power sources. By this approach PWM switching converters can be represented by a continuous, but nonlinear, electric circuit. By making reasonable assumptions, a linear transfer function model for the power converter is developed. The root

Guijun Yao; Lars Norum

1990-01-01

378

Drive System for Traction Applications Using 81-Level Converter  

E-print Network

. The voltage waveform is based on a cascade of n converters scaled in a "trinary" form, using three-state "h Principle The circuit of Fig.1 shows the basic topology of a "H" converter used for the implementation: +Vdc, -Vdc, and Zero. Driver Vdc + _ LOAD Figure 1. "H" module for building the multi-stage converter B

Catholic University of Chile (Universidad Católica de Chile)

379

Reduced Switching Frequency Computed PWM Method for Multilevel Converter Control  

E-print Network

. An experimental 11-level H-bridge multilevel converter with a first-on first-off switching strategy (usedReduced Switching Frequency Computed PWM Method for Multilevel Converter Control Zhong Du, Leon M computed PWM methods for 11-level multilevel converters to eliminate the specified harmonics in the output

Tolbert, Leon M.

380

Harmonic Elimination for Multilevel Converter with Programmed PWM Method  

E-print Network

wave is produced. An experimental 11-level H-bridge multilevel converter with a first- on, first. An experimental 11-level H-bridge multilevel converter with a first-on, first-off switching strategy (usedHarmonic Elimination for Multilevel Converter with Programmed PWM Method Zhong Du, Leon M. Tolbert

Tolbert, Leon M.

381

Decentralized control of a cascaded H-Bridge multilevel converter  

Microsoft Academic Search

Despite its inherently modular hardware structure, the control system of most cascaded H-bridge converters is usually highly centralized, and relies on a high bandwidth intra- converter communication system to transmit time critical control signals to the module controllers. In contrast, this paper presents a decentralized control strategy for a modular cascaded converter, where each module controller determines its own switching

W. Y. Kong; D. G. Holmes; B. P. McGrath

2011-01-01

382

Double input Z-source DC-DC converter  

Microsoft Academic Search

This paper proposes a double input dc-dc converter based on Z-source converters. In the proposed converter, the input dc voltage can be boosted and also input dc sources can deliver power to the load individually or simultaneously, so combination of a battery with one of the new energy sources such as solar array, wind turbine or fuel cell can be

Farzad Sedaghati; Ebrahim Babaei

2011-01-01

383

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

Microsoft Academic Search

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

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

2002-01-01

384

Design of LLC resonant converter using planar magnetic component  

Microsoft Academic Search

This paper presents the design and implementation of LLC resonant converter using planar magnetic component. In the LLC resonant converter, ZVS turn-on and ZCS turn-off of MOSFETs and diode rectifiers can be achieved over the entire operating range, respectively. Therefore, the switching loss is reduced and we can operate the converter at higher switching frequency. At that frequency, planar magnetic

Sihun Yang; Seiya Abe; Masahito Shoyama

2009-01-01

385

A low profile LLC resonant converter using novel planar transformer  

Microsoft Academic Search

In this paper, a low profile LLC resonant converter with two planar transformers is proposed for a slim SMPS (Switching Mode Power Supply). Design procedures and voltage gain characteristics on the proposed planar transformer and converter are described in detail. Two planar transformers applied to LLC resonant converter are connected in series at primary and in parallel by the center-tap

Eun-Soo Kim; Young-Jae No; Seung-Min Lee; Bong-Gun Chung; Jae-Sam Lee; Min-Soo Park; Dong-Young Huh

2012-01-01

386

A front end self-sustained LLC resonant converter  

Microsoft Academic Search

This paper presents a LLC resonant converter working with a self-sustained oscillation controller (SSOC). It provides the optimization of the converter elements ratings, and has an overall higher efficiency than when working with the conventional variable frequency controller (VF). A performance comparison for the converter is performed for both control techniques. It is shown that the self-sustained oscillation controller (SSOC)

Mohamed Z. Youssef; Praveen K. Jain

2004-01-01

387

A unified method to model resonant switching converters  

Microsoft Academic Search

A method for modeling resonant switching converters is developed. Its starting point is the output characteristic obtained from a static analysis. A canonical circuit model is proposed, whose fixed topology contains all the essential input-output and control properties of a resonant switching converter. A classification of the resonant switching converter has been done taking into account the main topologies which

M. Rico; V. Garcia; M. Hernando; F. Nuno; J. Sebastian; J. Uceda

1990-01-01

388

Evaluation of Conducted Noise of Resonant Switched Capacitor Converter  

Microsoft Academic Search

Conventional switched capacitor converters have an inherent drawback that their efficiency is much decreased as the output current is increased. To solve this problem we presented a novel resonant switched capacitor converter topology that uses a resonant operation instead of the forced charging and discharging operation. Its advantages over a conventional switched capacitor converter are a high efficiency and a

Masahito Shoyama; Fumitoshi Deriha; Tamotsu Ninomiya

2006-01-01

389

Output Voltage Control of Resonant Boost Switched Capacitor Converter  

Microsoft Academic Search

Conventional switched capacitor converters have an inherent drawback that their efficiency is much decreased as the output current is increased. To solve this problem we presented a novel switched capacitor converter topology that uses a resonant operation instead of the forced charging and discharging operation. Its advantage over a conventional switched capacitor converter is a high efficiency even in a

M. Shoyama; T. Ninomiya

2007-01-01

390

Sources of pressure drop in bead-bed catalytic converters  

Microsoft Academic Search

The peak power of some vehicles can be limited by exhaust system backpressure contributed by a catalytic converter. A computer model was developed for flow and pressure drop in a generalized single-bed bead-bed catalytic converter to determine the sources of converter pressure drop and suggest improved designs with lower restriction. In an accompanying experimental study, pressure losses in the components

Wendland

1987-01-01

391

Special-Purpose AC Converter Systems for Constant Horsepower Applications  

Microsoft Academic Search

The ac converter system discussed involves a design concept that results in a total cost that is competitive with dc converter systems when applied to specific application requirements. The particular application used as a reference is the limited speed range, constant horsepower grinder. This application may be satisfied by a constant voltage, adjustable frequency converter, and motor combination. First, the

Adolf C. Betke; James F. Billings; Kenneth P. Phillips

1972-01-01

392

Synthesis of Optimum Gain Functions for Static Power Converters  

Microsoft Academic Search

The optimization of transfer characteristics of static power converters has been largely based on converter definition in terms of its circuit configuration. Since converter circuits lack mathematical definition, this approach has failed to produce a comprehensive optimization procedure. Instead, it has led to several unwieldy optimization schemes with limited range of application. A different approach, which employs a more effective

Phoivos D. Ziogas

1983-01-01

393

Voltage balanced multilevel voltage source converter system  

DOEpatents

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.

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

1997-01-01

394

Optical analog-to-digital converter  

NASA Technical Reports Server (NTRS)

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

Evanchuk, Vincent L. (Inventor)

1984-01-01

395

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

396

A variable parameter thermionic energy converter  

E-print Network

, collector temperature and emitter tempera- ture relatively constant while varying the spacing down to a minimum of approximately 0. 5 mil, noting the variation of power output. 4 o c Spa c. ing F~i;, rp Power !ersu' Spacing wit, '"; gin&mum Power... Motive Diagram in Presence of Space Charge converters which have spacings of 4 to 40 mils and operate at a cesium pressure of 1 mm Hg or greater (2). The pressure, PC , in mm Hg is determined by the expression En P = 11. 0531-1. 35 Jn T 8- (10). ~01...

Bragg, Bobby Joe

2012-06-07

397

Converted silicon carbide technology developments for optics  

NASA Astrophysics Data System (ADS)

Silicon carbide structures fabricated by converting near-net-shape graphite preforms via Chemical Vapor Conversion (CVC) phase reaction have long provided improved performance components for electronics processing. In recent years, this same technology has been applied to the fabrication of simple and lightweighted mirrors and is moving into optical bench applications. To support the expanded applications, Poco has further evaluated the material properties of SUPERSiC® silicon carbide, developed technologies to mount silicon carbide mirrors on benches of similar and dissimilar materials, and fabricated complex monolithic geometries using in situ conversion bonding of mating graphite components. Overviews of each of these areas will be presented.

Duston, Christopher; Woestman, Ken; Vargas, Hugo; deBlonk, Brett

2007-09-01

398

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

399

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

400

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

401

Sources of pressure drop in bead-bed catalytic converters  

SciTech Connect

The peak power of some vehicles can be limited by exhaust system backpressure contributed by a catalytic converter. A computer model was developed for flow and pressure drop in a generalized single-bed bead-bed catalytic converter to determine the sources of converter pressure drop and suggest improved designs with lower restriction. In an accompanying experimental study, pressure losses in the components of two different converters were determined in an engine-dynamometer test cell over a wide range of engine operating conditions. The measured and predicted pressure drops were in good agreement. The experience gained in this study was used to develop a low-restriction converter for truck applications.

Wendland, D.W.

1987-01-01

402

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

403

Prototype of Free Piston Stirling Converter for Household Use  

NASA Astrophysics Data System (ADS)

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

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

404

Ultraviolet converter transients induced by electrons  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

405

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

406

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

407

Data Converters Performance at Extreme Temperatures  

NASA Technical Reports Server (NTRS)

Space missions often require radiation and extreme-temperature hardened electronics to survive the harsh environments beyond earth's atmosphere. Traditional approaches to preserve electronics incorporate shielding, insulation and redundancy at the expense of power and weight. However, a novel way of bypassing these problems is the concept of evolutionary hardware. A reconfgurable device, consisting of several switches interconnected with analog/digital parts, is controlled by an evolutionary processor (EP). When the EP detects degradation in the circuit it sends signals to reconfgure the switches, thus forming a new circuit with the desired output. This concept has been developed since the mid-90s, but one problem remains - the EP cannot degrade substantially. For this reason, extensive testing at extreme temperatures (-180' to 120(deg)C) has been done on devices found on FPGA boards (taking the role of the EP) such as the Analog to Digital and the Digital to Analog Converter. Analysis of the results has shown that FPGA boards implementing EP with some compensation may be a practical solution to evolving circuits. This paper describes results on the tests of data converters at extreme temperatures.

Rejeshuni, Rarnesham; Kumar, Nikil; Mao, James; Keymeulen, Didier; Zebulum, Ricardo S.; Stoica, Adrian

2006-01-01

408

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

409

Converting simple vegetation surveys in functional dynamics  

NASA Astrophysics Data System (ADS)

This study assessed an integrated method for estimating the structural and functional trends of Mediterranean vegetation based on simple field characterizations. Despite considerable effort made by scientists to estimate vegetation dynamics, most methods are too complex to be applied and quantification achieved by non-specialists. We propose an alternative approach that converts simple measures such as generic vegetation cover into life forms or life traits. We used the Stochastic Dynamic Methodology, a dynamic approach based on a sequential process, to calculate the functional response to succession and anthropogenic disturbances using Raunkiaer's life form spectra. Using derived scenarios, the model was able to successfully translate functional and structural trends from simple field descriptions. The simulations demonstrate that this methodology can be used in environmental studies, particularly when specialised field botanists are not available.

Fernandes, Claúdia; Cabral, João Alexandre; Crespí, António Luís; Hughes, Samantha Jane; Santos, Mário

2013-04-01

410

Mechanical vibration to electrical energy converter  

DOEpatents

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

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

2009-03-03

411

Transdermal delivery of Angiotensin Converting Enzyme inhibitors.  

PubMed

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

Helal, Fouad; Lane, Majella E

2014-09-01

412

Fluid energy converting method and apparatus  

SciTech Connect

A method and apparatus are disclosed for converting the kinetic energy of a moving fluid stream into useful work by means of a cascade of thin airfoils positioned therein. In one embodiment, the airfoils are provided with at least two degrees of freedom and adjacent airfoils are movable out of phase. The airfoils are subjected to the aerodynamically induced oscillations caused by the aeroelastic phenomenon known as flutter and the oscillatory movement is then harnessed to do useful work. In an alternate embodiment, a cascade of airfoils is mechanically oscillated within a moving fluid stream to increase the propulsion of the fluid. Where the fluid is a liquid, the cascade includes a plurality of hydrofoils.

Arnold, L.

1980-01-22

413

Fluid energy converting method and apparatus  

SciTech Connect

There is disclosed a method and apparatus for converting the kinetic energy of a moving fluid stream into useful work by means of a cascade of thin airfoils positioned therein. In one embodiment, the airfoils are provided with at least two degrees of freedom and adjacent airfoils are movable out of phase. The airfoils are subjected to the aerodynamically induced oscillations caused by the aeroelastic phenomenon known as flutter and the oscillatory movement is then harnessed to do useful work. In an alternate embodiment, a cascade of airfoils is mechanically oscillated within a moving fluid stream to increase the propulsion of the fluid. Where the fluid is a liquid, the cascade includes a plurality of hydrofoils.

Arnold, L.

1982-08-31

414

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

415

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

416

State space analysis and quick control methods for the series parallel resonant converter.  

E-print Network

??Resonant converters have been used as DC/DC power converters in many applications. Compared with hard-switching PWM converters,thesoft-switching resonant converter performs better for higher switching frequency… (more)

Chen, Hao.

2010-01-01

417

An integrated flyback converter for DC uninterruptible power supply  

SciTech Connect

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

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

1996-03-01

418

Synchronously Driven Power Converter Controller Solution for MedAustron  

E-print Network

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

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

2011-01-01

419

High-power Mode Converter of Overmoded Bent Circular Waveguide  

NASA Astrophysics Data System (ADS)

Based on the mode coupling theory, a TE01—TM11 mode converter was designed and optimal results were obtained. In this paper, bandwidth of mode converter with axis exponential structure is the largest, and mode converter with axis sinusoidal structure is the most compact in the case of the center frequency is 28GHz and the waveguide radius is 16mm. If the bending angle between input port and output port of mode converter was demanded for 90°, mode converter with axis parabola structure had the characteristics of compact structure, higher mode purity and larger relative bandwidth. Meanwhile, we found that the converter could be also used as TE11 mode transition with transmission efficiency above 99%. But due to bending angle of this structure was restricted, its center frequency and waveguide radius had the obvious corresponding relation.

Niu, Xin-Jian; Wang, Li-Xuan; Liu, Ying-Hui; Zhu, Xian-Neng; Yu, Xin-Hua

2014-09-01

420

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

421

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

422

Applications and benefits of catalytic converter thermal management  

Microsoft Academic Search

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

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

1996-01-01

423

Active harmonic elimination in multilevel converters using FPGA control  

Microsoft Academic Search

This paper presents an optimal total harmonic distortion (THD) control algorithm referred to as active harmonic elimination method for cascaded H-bridges multilevel converter control with unequal DC sources. First, the multilevel converter is decoupled into unipolar converters, the low order harmonics, such as the 5th, 7th, 11th and 13th are eliminated by using elimination theory, and the minimum THD combination

Zhong Du; Leon M. Tolbert; John N. Chiasson

2004-01-01

424

Analysis of LLC Resonant Converter considering effects of parasitic components  

Microsoft Academic Search

Nowadays the trend of power supply market is more inclined to high switching frequency, high efficiency and high power density. To meet this trend, resonant power supply holds more attraction, because it can be operated in high switching frequency with high efficiency. There are many resonant power supplies such as Series-Resonant Converter (SRC), Parallel-Resonant Converter (PRC) and Series-Parallel Resonant Converter

Byoung-Hee Lee; Moon-Young Kim; Chong-Eun Kim; Ki-Bum Park; Gun-Woo Moon

2009-01-01

425

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

Microsoft Academic Search

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

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

1990-01-01

426

The plasmatron as an advanced performance thermionic converter  

NASA Technical Reports Server (NTRS)

A study concerned with the improvement of thermionic converter performance has shown that the plasma arc drop of the conventional arc (ignited) mode converter can be suppressed by use of an auxiliary ion source as in a plasmatron converter. However, this improved performance is now limited to low current densities and narrow interelectrode spacings because of voltage losses due to plasma resistance. An examination of plasmatron performance characteristics for both argon and cesium plasma has shown that the argon plasmatron is superior.

Hansen, L. K.; Hatch, G. L.; Fitzpatrick, G. O.; Rasor, N. S.

1976-01-01

427

Novel Three-Phase AC–AC Sparse Matrix Converters  

Microsoft Academic Search

A novel three-phase ac-ac sparse matrix converter having no energy storage elements and employing only 15 IGBTs, as opposed to 18 IGBTs of a functionally equivalent conventional ac-ac matrix converter, is proposed. It is shown that the realization effort could be further reduced to only nine IGBTs in an ultra sparse matrix converter (USMC) in the case where only unidirectional

Johann W. Kolar; Frank Schafmeister; Simon D. Round; Hans Ertl

2007-01-01

428

Analysis of switched capacitor DC-DC step down converter  

Microsoft Academic Search

A 5V\\/1V switched capacitor (SC) DC-DC converter designed for a 0.18 ?m CMOS process is analyzed in detail, in this paper. Analytical equations are derived for the voltages and currents through the main components of the SC converter. The model includes switches, capacitors, equivalent series resistances and the load. The switches in the converter are represented by MOSFETs in the

Andrabadu K. P. Viraj; Gehan Amarathunga

2004-01-01

429

Novel Vortex Generator and Mode Converter for Electron Beams  

NASA Astrophysics Data System (ADS)

A mode converter for electron vortex beams is described. Numerical simulations, confirmed by experiment, show that the converter transforms a vortex beam with a topological charge m=±1 into beams closely resembling Hermite-Gaussian HG10 and HG01 modes. The converter can be used as a mode discriminator or filter for electron vortex beams. Combining the converter with a phase plate turns a plane wave into modes with topological charge m=±1. This combination serves as a generator of electron vortex beams of high brilliance.

Schattschneider, P.; Stöger-Pollach, M.; Verbeeck, J.

2012-08-01

430

GaxIn1-xAs thermophotovoltaic converters  

Microsoft Academic Search

Preliminary research into the development of single-junction Ga xIn1-xAs thermophotovoltaic (TPV) power converters is reviewed. The devices structures are grown epitaxially on single-crystal InP substrates. Converter band gaps of 0.50 -0.74 eV have been considered in accordance with modeling calculations. A 1-sun, AMO efficiency of 12.8% is reported for a lattice-matched, 0.74-eV converter. Converters with lower band gaps are fabricated

M. W. Wanlass; J. S. Ward; K. A. Emery; T. J. Coutts

1994-01-01

431

High-power converters for space applications  

NASA Astrophysics Data System (ADS)

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

1991-06-01

432

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

433

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

434

Photoresponsive Polymers: Converting Light to Mechanical Work  

NASA Astrophysics Data System (ADS)

The ability to remotely control the creation of mechanical work, rapidly, with high spatial precision, and over long distances, offers many intriguing possibilities. Whether driving direct conformational changes, initiating reversible chemical reactions to release stored strain, or converting the photon to a local temperature increase, combinations of photoactive units, nanoparticles, ordered mesophases and polymeric networks are providing an expansive array of photo-responsive polymer options. By combining these material responses with kinematic concepts, mechanical devices can be demonstrated that exhibiting tunable and controllable macroscopic deformation, high-frequency oscillation or directional motion. Specifically, we will discuss recent investigation of liquid crystal polymer networks containing main chain and pendent azobenzene moieties (azo-LCN) with modulus ˜1.3GPa that are actuated at the absorptive overlap of the cis and trans confirmers (442 nm). Cantilevers and unconstrained beams of these azo-LCNs can be controlled by polarization angle of the source, as well as by a specific optical exposure history (on-off), with responses ranging from lateral motion to oscillations in excess of 30Hz. These phenomena reflect an underlying interaction between the mesophase order, the network architecture and kinematic constraints of the exposed material. In collaboration with Timothy Bunning, Timothy White, Hilmar Koerner, Air Force Research Laboratory; and Nelson Tabiryan, BEAM Co.

Vaia, Richard A.

2009-03-01

435

Optimization of Aperiodic Waveguide Mode Converters  

SciTech Connect

Previous studies by Haq, Webb and others have demonstrated the design of aperiodic waveguide structures to act as filters and mode converters. These aperiodic structures have been shown to yield high efficiency mode conversion or filtering in lengths considerably shorter than structures using gradual transitions and periodic perturbations. The design method developed by Haq and others has used mode-matching models for the irregular, stepped waveguides coupled with computer optimization to achieve the design goal using a Matlab optimization routine. Similar designs are described here, using a mode matching code written in Fortran and with optimization accomplished with the downhill simplex method with simulated annealing using an algorithm from the book Numerical Recipes in Fortran. Where Haq et al. looked mainly for waveguide shapes with relatively wide cavities, we have sought lower profile designs. It is found that lower profiles can meet the design goals and result in a structure with lower Q. In any case, there appear to be very many possible configurations for a given mode conversion goal, to the point that it is unlikely to find the same design twice. Tolerance analysis was carried out for the designs to show edge sensitivity and Monte Carlo degradation rate. The mode matching code and mode conversion designs were validated by comparison with FDTD solutions for the discontinuous waveguides.

Burke, G J; White, D A; Thompson, C A

2004-12-09

436

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

437

Three-phase, power quality improvement ac\\/dc converters  

Microsoft Academic Search

The generation of harmonics and reactive power flow in a power system is greatly influenced by the widespread use of power electronic converters in addition to other sources of harmonics and reactive power. The design, development and successful application of single-phase, power quality improvement converters in domestic, commercial and industrial environment has made possible the design and development of three-phase,

Abdul Hamid Bhat; Pramod Agarwal

2008-01-01

438

Sequential color video to parallel color video converter  

NASA Technical Reports Server (NTRS)

The engineering design, development, breadboard fabrication, test, and delivery of a breadboard field sequential color video to parallel color video converter is described. The converter was designed for use onboard a manned space vehicle to eliminate a flickering TV display picture and to reduce the weight and bulk of previous ground conversion systems.

1975-01-01

439

BabeLO--An Extensible Converter of Programming Exercises Formats  

ERIC Educational Resources Information Center

In the last two decades, there was a proliferation of programming exercise formats that hinders interoperability in automatic assessment. In the lack of a widely accepted standard, a pragmatic solution is to convert content among the existing formats. BabeLO is a programming exercise converter providing services to a network of heterogeneous…

Queiros, R.; Leal, J. P.

2013-01-01

440

Reversed flow converter for emission control after automotive engines  

Microsoft Academic Search

A concept of catalytic reversed flow converter (RFC) is discussed for three emerging areas of emission control after automotive engines. The first potential application concerns with oxidation of methane and CO emitted from dual fueled, natural gas\\/diesel engines (DDF). The behavior of RFC is studied under typical transient conditions of DDF engine exhaust using mathematical modeling and experiments with converter

Yu. Sh. Matros; G. A. Bunimovich; V. O. Strots; E. A. Mirosh

1999-01-01

441

Advanced catalytic converter system for natural gas powered diesel engines  

Microsoft Academic Search

The paper discusses the development of catalytic converter for aftertreatment of exhaust gas from diesel engines powered with natural gas. The converter, operated with periodical reversals of the flow, ensures destruction of CO and hydrocarbons, including methane. Both computer simulation and engine testing results are presented.

Vadim O. Strots; Grigorii A. Bunimovich; Yurii Sh. Matros; Ming Zheng; Edward A. Mirosh

1998-01-01

442

Parasitic losses modeling of a series resonant converter circuit  

Microsoft Academic Search

This paper describes the formulation and verification of a SPICE macromodel for a practical series resonant converter circuit with parasitics. The macromodel is obtained by using a new proposed model of the power devices compared to the generic macromodel we have previously published. A 600 W series resonant converter has been built. Measurements of losses in each power device of

S. C. Wong; A. D. Brown; Y. S. Lee; S. W. Ng

1997-01-01

443

Digital parallel-to-series pulse-train converter  

NASA Technical Reports Server (NTRS)

Circuit converts number represented as two level signal on n-bit lines to series of pulses on one of two lines, depending on sign of number. Converter accepts parallel binary input data and produces number of output pulses equal to number represented by input data.

Hussey, J.

1971-01-01

444

Two Applications of Direct Digital Down Converters in Beam Diagnostics*  

E-print Network

. The technologies of direct digital down converters, digital frequency synthesis, and digital signal processing of the two reference signals. INTRODUCTION The technologies of digital down converters (DDC) and digital -SINCOS EXTERNAL SYNC JTAG PORT MPU INTERFACE Q I Q I SERIAL OR PARALLEL OUTPUTS 14 DIGITIZED IF SIGNAL

445

Design and Performance of a Converter Optimized AC Machine  

Microsoft Academic Search

The design and performance of a unique concentrated winding machine specifically designed for operation with a static power converter is described. When operating in tonjunction with a converter supply, the machine is theoretically capable of 15 percent more power output for the same active copper and iron than a conventionally designed synchronous machine of the same rating. The performance of

Thomas A. Lipo; Feng X. Wang

1984-01-01

446

Harmonic reduction in thyristor converters by harmonic current injection  

Microsoft Academic Search

The paper describes analytical and experimental results for a new method of current harmonic reduction in thyristor converters. The principle of the method is to modify the current waveforms on the d.c. windings of the converter transformer by injecting harmonic currents at a particular frequency. In practice, third harmonic currents of the power frequency is most efficient. Experimental results carried

A. Ametani

1976-01-01

447

Control of H-bridge based multilevel converters  

Microsoft Academic Search

Multilevel converters are suitable for high voltage and high power applications. Among them H-bridge ones have encountered good success due to their simpler layout and the reduced number of components over the counterparts. H-bridge multilevel converters used as active rectifiers represent an attractive solution in traction systems due to the possibility to reduce the AC filter size and to boost

A. Dell'Aquila; V. G. Monopoli; M. Liserre

2002-01-01

448

An improved design method of LLC resonant converter  

Microsoft Academic Search

For LLC resonant converter, design of the resonant tank influences much of the performance. In traditional design ideas, the transformer magnetizing inductance values are more dependent on engineering experience. In this paper, a model is constructed based on the proposed “current angle” theory by accurately calculating the LLC resonant converter in resonant frequency, and an improved design method of LLC

Xue Zhang; Wei You; Wei Yao; Shen Chen; Zhengyu Lu

2012-01-01

449

A Novel Precise Design Method for LLC Series Resonant Converter  

Microsoft Academic Search

In this paper, a novel precise analysis method based on time domain analysis for LLC series resonant converter is proposed and a clear design guide line is given. Because LLC resonant converter has simple structure, high efficiency and high switching frequency capability, it is widely used nowadays. To achieve an optimized design and propose a clear design guide line, understanding

Teng Liu; Ziying Zhou; Aiming Xiong; John Zeng; Jianping Ying

2006-01-01

450

Paralleling of LLC resonant converters using frequency controlled current balancing  

Microsoft Academic Search

Paralleling of two LLC resonant converters leads to a significant reduction of current stress in the output filter capacitor, provided that the driving signals of both converters are of equal frequency and with constant phase shift of 90deg. However, non influenceable tolerances of the circuit elements, especially those of the resonant tank circuit, cause unbalanced power distribution between the paralleled

H. Figge; T. Grote; N. Froehleke; J. Boecker; P. Ide

2008-01-01

451

Standby Mode Control Circuit Design of LLC Resonant Converter  

Microsoft Academic Search

This paper proposes to use the burst mode control as the standby control of the LLC resonant converter. A new standby control circuit is designed and implemented for the LLC converter. The experimental results show that the function of the proposed standby control circuit has been achieved and it has no compatibility problem with the other parts of the LLC

Yu Fang; Dehong Xu; Yanjun Zhang; Fengchuan Gao; Lihong Zhu; Yi Chen

2007-01-01

452

Efficiency study for a 150W LLC resonant converter  

Microsoft Academic Search

The paper presents and analyzes the efficiency of a 150 W LLC resonant converter in order to compare with the results obtained with a conventional 150 W flyback version. The experimental results of the LLC resonant converter show a maximum efficiency of 94%, and an efficiency of 92% under a full-load condition. Using the presented theoretical equations and design methods,

Chun-An Cheng; Hung-Wen Chen; En-Chih Chang; Chun-Hsien Yen; Kun-Jheng Lin

2009-01-01

453

Analysis and implementation of dual-output LLC resonant converter  

Microsoft Academic Search

A dual-output LLC resonant converter for LCD-TV applications is presented in this paper. Based on the LLC resonant behavior, the power MOSFETs are turned on at zero voltage switching (ZVS) and secondary rectifier diodes are turned off at zero current switching (ZCS). In the proposed converter, the primary windings of two transformers are connected in series so that the primary

B.-R. Lin; J.-J. Chen; C.-L. Yang

2008-01-01

454

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

455

A unified analysis of converters with resonant switches  

NASA Astrophysics Data System (ADS)

Quasiresonant converters are single-switch resonant converters featuring zero-current or zero-voltage switching. Understanding of the topological structure uniting these converters and the PWM converters on which they are based is used as the basis of general models of their dc and low-frequency ac behavior. An expression is derived that yields the dc conversion ratio of a quasiresonant converter in terms of the conversion ratio of the underlying PWM topology. A small-signal, low-frequency dynamic model is developed whose parameters also incorporate the PWM conversion ratio. The dc and ac models reveal that any quasiresonant converter with a full-wave resonant switch has dc and low-frequency behavior identical to that of its PWM parent, with switching-frequency control replacing duty-ratio control. Converters with half-wave resonant switches act more like PWM converters under current programming or discontinuous conduction mode, exhibiting lossless damping in the small-signal model and output resistance at dc.

Freeland, Steve; Middlebrook, R. D.

456

Aircraft power system harmonics involving single-phase PFC converters  

Microsoft Academic Search

AC-DC converters with active power factor correction (PFC) are replacing uncontrolled diode rectification circuits on commercial jet airplanes in order to meet harmonic distortion limits imposed by new airborne electrical system power quality standards. The high line frequency of airborne AC power systems presents a major challenge for the design of PFC converters capable of meeting these standards. This paper

Jian Sun; Min Chen; KAMIAR J. KARIMI

2008-01-01

457

Thermal-To-Electric Converter With Greater Power Density  

NASA Technical Reports Server (NTRS)

Proposed design for alkali-metal thermal-to-electric converter (AMTEC) incorporates refinements to increase power density and reduce input temperature below typical prior design. Converter has compact, planar configuration. Cells stacked densely with remote condenser for thermal efficiency and high power density. Either liquid- or vapor-fed cells utilized. Heat fed-in at lower temperature.

Williams, Roger M.; Suitor, Jerry W.; Jeffries-Nakamura, Barbara; Underwood, Mark L.; Ryan, Margaret A.; O'Connor, Dennis

1992-01-01

458

System management of a wind-energy converter  

Microsoft Academic Search

Wind energy converters are commonly used in converting wind energy into useful mechanical and electrical energies. But the problems of smooth start, tower effect and oscillations caused by aerodynamic forces acting on the rotor cause fluctuations in its power output. A system management was designed to reduce these effects. It consists of a microcontroller. This was verified with the help

Charles Lemogo Kana; Manoharan Thamodharan; Albrecht Wolf

2001-01-01

459

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

460

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

461

An experimental fuzzy controller for DC-DC converters  

Microsoft Academic Search

A fuzzy control algorithm for switching power converters is proposed. Being free of complex equations and heavy computation, the control algorithm can be implemented by a digital controller using a fixed point signal processor. This paper presents experimental results which demonstrate the capability of the fuzzy controller in regulating high speed switching DC\\/DC power converters

W. C. So; C. K. Tse; Y. S. Lee

1995-01-01

462

Converting hard copy documents for electronic dissemination  

SciTech Connect

Since the advent of computer systems, the goal of a paperless office, and even a paperless society, has been pursued. While the normal paper flow in an organization is far from totally automated, particularly for items requiring signatures or authorizations, electronic information dissemination is becoming an almost simple task. The reasons for providing on-line documents are many and include faster and easier access for everyone, elimination of printing costs, reduction of wasted shelf and desk space, and the security of having a centrally-located, always up-to-date document. New computer software even provides the user with the ability to annotate documents and to have bookmarks so that the old scribbled-in and dog-eared manual can be replaced without loosing this `customizability`. Moreover, new hypermedia capabilities mean that documents can be read in a non-linear fashion and can include color figures and photographs, audio, and even animation sequences, capabilities which exceed those of paper. The proliferation of network-based information servers, coupled with the growth of the Internet, has enticed academic, governmental, and even commercial organizations to provide increasing numbers of documents and data bases in electronic form via the network, not just to internal staff, but to the public as well. Much of this information, which includes everything from mundane company procedures to spiffy marketing brochures, was previously published only in hard copy. Converting existing documents to electronic form and producing only electronic versions of new documents poses some interesting challenges to the maintainer or author.

Hoffman, F.

1994-12-31

463

Three-phase step-down reversible AC-DC power converter  

Microsoft Academic Search

Bidirectional DC current flow is not a natural feature of the buck (step-down) switch-mode rectifier, which leaves it at a disadvantage to boost (step-up) designs. A circuit topology is presented that allows bidirectional flow and which, by dual use of components, uses fewer devices than anti-parallel bridges. Sinusoidal current, controlled displacement factor, and variable voltage transfer ratio are demonstrated in

Tim C. Green; Mohamed H. Taha; N. A. Rahim; B. W. Williams

1997-01-01

464

Three-phase step-down reversible AC-DC power converter  

Microsoft Academic Search

Bidirectional DC current flow is not a natural feature of the buck (step-down) switch-mode rectifier which leaves it at a disadvantage to boost (step-up) designs. A circuit topology is presented that allows bidirectional flow and which, by dual use of components, uses less devices than anti-parallel bridges. Sinusoidal current, controlled displacement factor and variable voltage transfer ratio are demonstrated in

N. A. Rahim; T. C. Green; B. W. Williams

1995-01-01

465

Postoperational examination of an externally configured thermionic converter  

NASA Technical Reports Server (NTRS)

An externally configured thermionic converter was operated for 200 h. The converter was disassembled and examined to determine internal changes as a result of operation. The metal/ceramic seals and all joints were unaffected by operation. Converter output voltage and operational time were sufficient to produce electrolysis of stabilized zirconia spacers used in the converter. Surface analysis of the electrode surfaces indicated the presence on the tungsten emitter of only oxygen, carbon, and silicon. The niobium collector was, however, 25 to 40% covered with other elements. This coverage represented all elements present within the converter as construction materials other than silicon and tungsten, which were not detected on the collector, and carbon, which was detected only in small amounts.

Phillips, W. M.

1973-01-01

466

A study of Schwarz converters for nuclear powered spacecraft  

NASA Technical Reports Server (NTRS)

High power space systems which use low dc voltage, high current sources such as thermoelectric generators, will most likely require high voltage conversion for transmission purposes. This study considers the use of the Schwarz resonant converter for use as the basic building block to accomplish this low-to-high voltage conversion for either a dc or an ac spacecraft bus. The Schwarz converter has the important assets of both inherent fault tolerance and resonant operation; parallel operation in modular form is possible. A regulated dc spacecraft bus requires only a single stage converter while a constant frequency ac bus requires a cascaded Schwarz converter configuration. If the power system requires constant output power from the dc generator, then a second converter is required to route unneeded power to a ballast load.

Stuart, Thomas A.; Schwarze, Gene E.

1987-01-01

467

1.2 MW dc-dc converter  

NASA Astrophysics Data System (ADS)

A dc-dc converter has been developed to charge capacitors to 16 kV from a 400 V battery bank. It is designed to charge an 8.5 MJ bank nine times in 3 min. The converter is comprised of six modules, each producing 12.5 A of charging current, and an enclosure which houses the modules and provides control power and a master controller. The six 200 kW modules have a combined power rating of 1.2 MW. The pulse width modulation converter system operates at 24 kHz and contains inverters with power MOSFETs as the principal inverter components, 200 kW transformers and inductors, and full bridge rectifiers with fast recovery diodes. The converter modules have a volume power density of 1.0 MW/cu m and a mass power density of 1.2 kW/kg. The converter design and test results are described.

Homeyer, W. G.; Callanan, R. J.; Bowles, E. E.; Nerem, A.

1993-01-01

468

Magnet Technology for Power Converters: Nanocomposite Magnet Technology for High Frequency MW-Scale Power Converters  

SciTech Connect

Solar ADEPT Project: CMU is developing a new nanoscale magnetic material that will reduce the size, weight, and cost of utility-scale PV solar power conversion systems that connect directly to the grid. Power converters are required to turn the energy that solar power systems create into useable energy for the grid. The power conversion systems made with CMU’s nanoscale magnetic material have the potential to be 150 times lighter and significantly smaller than conventional power conversion systems that produce similar amounts of power.

None

2012-02-27

469

Insightful analysis of carrier PWM algorithms for direct AC-AC matrix converter based on voltage-source converter modules  

Microsoft Academic Search

This paper discusses the carrier PWM algorithms suitable for the direct AC-AC matrix converter composed of three three-phase voltage source converter modules. The relationship between the conjugated and nonconjugated terms from the dyadic matrix control theory and the harmonic performance of input current and output voltage are outlined through extended harmonic analysis. Furthermore, two algorithms that result in a larger

D. O. Neacsu; A. Alistar; M. Kazerani

2002-01-01

470

Analysis and Design of Single-Stage AC\\/DC $LLC$ Resonant Converter  

Microsoft Academic Search

Analysis and design of a single-stage LLC resonant converter are proposed. A single-stage converter uses only one con- trol signal to drive two power converters, a power factor corrector (PFC) converter and a dc\\/dc converter, for reducing the cost of the system. However, this simplicity induces power imbalance between two converters, and then, the bus voltage between two converters drifts

Shih-Yu Chen; Zhu Rong Li; Chern-Lin Chen

2012-01-01

471

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

472

Architecture for a High-to-Medium-Voltage Power Converter  

NASA Technical Reports Server (NTRS)

A power converter now undergoing development is required to operate at a DC input potential ranging between 5.5 and 10 kV and a DC output potential of 400 V at a current up to 25 A. This power converter is also required to be sufficiently compact and reliable to fit and operate within the confines of a high-pressure case to be lowered to several miles (approx.5 km) below the surface of the ocean. The architecture chosen to satisfy these requirements calls for a series/ parallel arrangement of 48 high-frequency, pulse-width-modulation (PWM), transformer-isolation DC-to-DC power converter blocks. The input sides of the converter blocks would be connected in series so that the input potential would be divided among them, each of them being exposed to an input potential of no more than 10 kV/48 . 210 V. The series connection of inputs would also enforce a requirement that all the converter blocks operate at the same input current. The outputs of the converter blocks would be connected in a matrix comprising 6 parallel legs, each leg being a cascade of eight outputs wired in series (see figure). All the converter blocks would be identical within the tolerances of the values of their components. A single voltage feedback loop would regulate the output potential. All the converter blocks would be driven by the same PWM waveform generated by this feedback loop. The power transformer of each converter block would have a unity turns ratio and would be capable of withstanding as much as 10 kVDC between its primary and secondary windings. (Although, in general, the turns ratio could be different from unity, the simplest construction for minimizing leakage and maximizing breakdown voltage is attained at a turns ratio of unity.)

Vorpenian, Vatche

2008-01-01

473

Study of switching transients in high frequency converters  

NASA Technical Reports Server (NTRS)

As the semiconductor technologies progress rapidly, the power densities and switching frequencies of many power devices are improved. With the existing technology, high frequency power systems become possible. Use of such a system is advantageous in many aspects. A high frequency ac source is used as the direct input to an ac/ac pulse-density-modulation (PDM) converter. This converter is a new concept which employs zero voltage switching techniques. However, the development of this converter is still in its infancy stage. There are problems associated with this converter such as a high on-voltage drop, switching transients, and zero-crossing detecting. Considering these problems, the switching speed and power handling capabilities of the MOS-Controlled Thyristor (MCT) makes the device the most promising candidate for this application. A complete insight of component considerations for building an ac/ac PDM converter for a high frequency power system is addressed. A power device review is first presented. The ac/ac PDM converter requires switches that can conduct bi-directional current and block bi-directional voltage. These bi-directional switches can be constructed using existing power devices. Different bi-directional switches for the converter are investigated. Detailed experimental studies of the characteristics of the MCT under hard switching and zero-voltage switching are also presented. One disadvantage of an ac/ac converter is that turn-on and turn-off of the switches has to be completed instantaneously when the ac source is at zero voltage. Otherwise shoot-through current or voltage spikes can occur which can be hazardous to the devices. In order for the devices to switch softly in the safe operating area even under non-ideal cases, a unique snubber circuit is used in each bi-directional switch. Detailed theory and experimental results for circuits using these snubbers are presented. A current regulated ac/ac PDM converter built using MCT's and IGBT's is evaluated.

Zinger, Donald S.; Elbuluk, Malik E.; Lee, Tony

1993-01-01

474

Implementation of optimal trajectory control of series resonant converter  

NASA Technical Reports Server (NTRS)

Due to the presence of a high-frequency LC tank circuit, the dynamics of a resonant converter are unpredictable. There is often a large surge of tank energy during transients. Using state-plane analysis technique, an optimal trajectory control utilizing the desired solution trajectory as the control law was previously proposed for the series resonant converters. The method predicts the fastest response possible with minimum energy surge in the resonant tank. The principle of the control and its experimental implementation are described here. The dynamics of the converter are shown to be close to time-optimal.

Oruganti, Ramesh; Yang, James J.; Lee, Fred C.

1987-01-01

475

Status of NASA's Stirling space power converter program  

NASA Astrophysics Data System (ADS)

An overview is presented of the NASA free-piston stirling space power converter technology program. The authors discuss Stirling experience in space and progress toward 1050 K and 1300 K Stirling space power converters. Fabrication is nearly completed for the 1050 K component test power converter (CTPC); results of motoring tests of the cold end (525 K), are presented. The success of these and future designs is dependent upon supporting research and technology efforts including heat pipes, bearings, superalloy joining technologies, high efficiency alternators, life and reliability testing and predictive methodologies. The authors provide an update of progress in some of these technologies.

Dudenhoefer, James E.; Winter, Jerry M.

476

Phase substitution of spare converter for a failed one of parallel phase staggered converters  

NASA Technical Reports Server (NTRS)

Failure detection and substitution of a spare module is provided in a system having a plurality of phase staggered modules connected in parallel to deliver regulated voltage from an unregulated source. Phase control signals applied to the active converter modules are applied to the spare module through NOR gates associated with and disabled by the power output of respective modules such that failure of any one enables its phase control signal to be applied to the spare module, thus controlling the spare module to operate in the phase position of the failed module. A NAND gate detects when any one active module fails and enables a gate in the spare module, thus activating the spare module.

Mclyman, W. T.; Wester, G. W. (inventors)

1977-01-01

477

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

478

Burnout sensitivity of power MOSFETs operating in a switching converter  

SciTech Connect

Heavy ion tests of a switching converter using power MOSFETs have allowed the authors to identify the main parameters which affect the burnout sensitivity of these components. The differences between static and dynamic conditions are clarified in this paper.

Tastet, P.; Garnier, J. (Centre National d'Etudes Spatiales, Toulouse (France)); Constans, H.; Tizon, A.H. (EREMS, Flourens (France))

1994-06-01

479

INTERIOR OF BESSEMER BUILDING. LOOKING EAST. PLATFORM WHERE CONVERTERS STOOD. ...  

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

INTERIOR OF BESSEMER BUILDING. LOOKING EAST. PLATFORM WHERE CONVERTERS STOOD. - Jones & Laughlin Steel Corporation, Pittsburgh Works, Morgan Billet Mill Engine, 550 feet north of East Carson Street, opposite South Twenty-seventh Street, Pittsburgh, Allegheny County, PA

480

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

481

Quantum Mechanical Modeling of Surface Reactions in Storage Catalytic Converters.  

E-print Network

??Pollutant reduction of internal combustion engines plays an essential role in automotive industry research and development. Exhaust-gas after-treatment using catalytic converters is of key importance… (more)

Tutuianu, Monica

2007-01-01

482

A global maximum power point tracking DC-DC converter  

E-print Network

This thesis describes the design, and validation of a maximum power point tracking DC-DC converter capable of following the true global maximum power point in the presence of other local maximum. It does this without the ...

Duncan, Joseph, 1981-

2005-01-01

483

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

484

Multilevel Converter Topologies for Utility Scale Solar Photovoltaic Power Systems  

E-print Network

and phase angle of the inverter cells is proposed. This improves differential power processing amongst cells while keeping the voltage and current ratings of the devices low. A battery energy storage system for the multilevel PV converter has also been...

Essakiappan, Somasundaram

2014-04-30

485

Silicon RF-Photonic Filter and Down-Converter  

E-print Network

An RF-photonic filter and down-converter system based on a compact and fully tunable silicon optical filter has been demonstrated and analyzed. Its frequency down-conversion was implemented using optical heterodyne detection ...

Tu, Kun-Yii

486

8. INTERIOR VIEW, SHOWING CONVERTED STAND FOR COMPRESSOR RESEARCH. ...  

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

8. INTERIOR VIEW, SHOWING CONVERTED STAND FOR COMPRESSOR RESEARCH. - Wright-Patterson Air Force Base, Area B, Building No. 20A, Propeller Test Complex, Seventh Street, from E to G Streets, Dayton, Montgomery County, OH

487

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

488

Laser-to-electricity energy converter for short wavelengths  

NASA Technical Reports Server (NTRS)

Short-wavelength energy converter can be made using Schottky barrier structure. It has wider band gap than p-n junction silicon semiconductors, and thus it has improved response at wavelengths down to and including ultraviolet region.

Stirn, R. J.; Yeh, Y. C. M.

1975-01-01

489

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

490

Visceral angioedema due to angiotensin-converting enzyme inhibitor therapy.  

PubMed

Visceral angioedema is an uncommon but serious complication of therapy with angiotensin-converting enzyme (ACE) inhibitors. We report a case, review the literature, and discuss the incidence, features, and clinical recognition of this condition. PMID:21536824

Korniyenko, Aleksandr; Alviar, Carlos L; Cordova, Juan P; Messerli, Franz H

2011-05-01

491

Output ripple analysis of multiphase DC-DC converters  

Microsoft Academic Search

This paper presents an output ripple analysis of multiphase DC-DC power converters having an output LC filter. Analytical expressions for the output voltage ripple of two- and three-phase DC-DC power converters are derived. Influence of the coupling coefficient of the output filter inductor on the output ripple is investigated. Because the unique parameters of the LC filter cannot be determined

Pekik A. Dahono; Slamet Riyadi; Ahmad Mudawari; Yanuarsyah Haroen

1999-01-01

492

Low cost fuel cell converter system for residential power generation  

Microsoft Academic Search

The high installation cost is the major obstacle of the commercialization of the solid oxide fuel cell for distributed power generation. This paper presents a new low cost 10-kW converter system to overcome this obstacle. The proposed system consists of an isolated dc-dc converter to boost the fuel cell voltage to 400 V dc and a pulse-width modulated inverter with

Jin Wang; Fang Z. Peng; Joel Anderson; Alan Joseph; Ryan Buffenbarger

2004-01-01

493

Platinum emission rate of automobiles with catalytic converters  

Microsoft Academic Search

Inconsistent data presently available on the platinum emission rate of cars in Germany equipped with catalytic converters\\u000a are evaluated. Automobile sources of Pt other than autocatalysts are quantified and found to be 1–6 orders of magnitudes lower\\u000a than the Pt emissions attributed to catalytic converters. A transfer of emission rates derived from test stand experiments\\u000a to more realistic street conditions

Eckard Helmers

1997-01-01

494

Modeling dynamic phenomena in 3-way catalytic converters  

Microsoft Academic Search

Mathematical modeling of 3-way catalytic converter (3WCC) operation is increasingly employed in automotive catalyst and converter systems optimization. The majority of the models employed in this direction employ a `quasi-steady’ approach in the reaction kinetics computations. This approach is useful in predicting real-world performance of the catalyst. However, certain improvements, that are produced by the application of specially tuned redox

Grigorios C. Koltsakis; Anastasios M. Stamatelos

1999-01-01

495

Efficiency improvement of piezoelectric-transformer DC-DC converter  

Microsoft Academic Search

Piezoelectric-transformers (PT) have a lot of merits in comparison with magnetic transformers. We have previously presented some types of piezoelectric-transformer DC-DC converters (PT-converters) for AC-adapters, but their efficiency was restricted. The maximum efficiency was less than 80%. Furthermore, the frequency characteristics of efficiency are not good due to the power loss generated in the input filter circuit of the PT.

T. Yamane; S. Hamamura; Toshiyuki Zaitsu; T. Minomiya; M. Shoyama; Yoshiaki Fuda

1998-01-01

496

A unified SPICE compatible average model of PWM converters  

Microsoft Academic Search

A simple, unified, and topology-independent model of basic pulse-width modulated (PWM) power converters is developed using the switched inductor approach presented by S. Ben-Yaakov (1989). The model is compatible with SPICE or other similar general-purpose electronic circuit simulators. It can be used to simulate DC, small signal, and transient behavior of PWM converters operating in both discontinuous conduction mode (DCM)

Yair Amran; F. Huliehel; S. Ben-Yaakov

1991-01-01

497

Small-signal model for the series resonant converter  

NASA Technical Reports Server (NTRS)

The results of a previous discrete-time model of the series resonant dc-dc converter are reviewed and from these a small signal dynamic model is derived. This model is valid for low frequencies and is based on the modulation of the diode conduction angle for control. The basic converter is modeled separately from its output filter to facilitate the use of these results for design purposes. Experimental results are presented.

King, R. J.; Stuart, T. A.

1985-01-01

498

Theoretical analysis and optimal design of LLC resonant converter  

Microsoft Academic Search

A LLC resonant topology is analyzed to derive efficiency and cost optimal design for wide input ranges and load variations. In the LLC converter, a wide range of output power is controlled with only a narrow variation in operating frequency since this converter is capable of both step-up and step-down. In addition, ZVS turn-on and ZCS turn-off of MOSFETs and

Jee-hoon Jung; Joong-gi Kwon

2007-01-01

499

Design of LLC resonant converter with integrated magnetic technology  

Microsoft Academic Search

Under the condition of 300-400 V input voltage and 48 V output voltages, this paper presents a thin-film integrated magnetic converter based on LLC resonant converter. In this paper, equivalent circuit of integrated magnetic components was gained and its working modes were discussed, then its design results were given. Thin-film technology was used to design integrated magnetic components. At last,

Cheng Ruijun; Yang Yugang; Jiang Ying

2005-01-01

500

High efficiency, inductorless step-down DC\\/DC converter  

Microsoft Academic Search

A high efficiency, inductorless step-down DC\\/DC converter is proposed. High efficiency is achieved through the combination of the fractional conversion ratio charge pump and load current sensing circuit. The circuits have been designed in the TSMC 0.25mum 2.5V\\/5V mixed signal CMOS process. The DC\\/DC converter has an output voltage of 1.8V (load current les 200mA) with the accuracy of plusmn

Shao Bin; Yang Yujia; Wang Ying; Hong Zhiliang

2005-01-01