These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

An improved Flyback converter  

Microsoft Academic Search

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

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

2009-01-01

2

A 400 W flyback converter  

Microsoft Academic Search

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

B. Assow

1989-01-01

3

Active-clamping quad-flyback converter  

Microsoft Academic Search

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

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

2009-01-01

4

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

Microsoft Academic Search

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

Hongmei Wang; Chunying Gong; Haixiao Ma; Yangguang Yan

2006-01-01

5

Active-Clamping ZVS Flyback Converter Employing Two Transformers  

Microsoft Academic Search

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

Yu-Kang Lo; Jing-Yuan Lin

2007-01-01

6

Analysis, design and implementation of an active clamp flyback converter  

Microsoft Academic Search

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

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

2005-01-01

7

Active-clamp ZVS two-switch flyback converter  

Microsoft Academic Search

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

Dakshina Murthy-Bellur; Marian K. Kazimierczuk

2011-01-01

8

A Single-stage Boost-Flyback PFC Converter  

Microsoft Academic Search

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

Zhao Qinglin; Wen Yi; Wu Weiyang; Chen Zhe

2006-01-01

9

Design of high efficiency Flyback converter with energy regenerative snubber  

Microsoft Academic Search

The flyback converter is frequently used for multiple outputs and low power application due to its simplicity and both step-up and step-down characteristics. However, the high leakage inductance of the flyback transformer can causes high voltage spike and could damage the main transistor when the switch is turned off. Therefore, a turn-off snubber is needed to limit the peak voltage

Chih-Sheng Liao; Keyue M. Smedley

2008-01-01

10

Coupled Dual Interleaved Flyback Converter for High Input Voltage Application  

E-print Network

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

Lehman, Brad

11

Dynamic modeling and controller design of flyback converter  

Microsoft Academic Search

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

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

1999-01-01

12

Cross regulation in flyback converters: analytic model and solution  

Microsoft Academic Search

An analytical model for studying cross regulation among the multiple outputs of flyback converters is presented in this paper. Both the theoretical and experimental results show that the cross regulation can be improved by lowering the clamp voltage, which has not been previously reported. Many other factors, such as the leakage inductance in primary and secondary windings, the magnetizing inductance,

Chuanwen Ji; K. M. Smedley; K. King

2001-01-01

13

A High Efficiency Flyback Converter With New Active Clamp Technique  

Microsoft Academic Search

This paper proposes a flyback converter with a new noncomplementary active clamp control method. With the proposed control method, the energy in the leakage inductance can be fully recycled. The soft switching can be achieved for the main switch and the absorbed leakage energy is transferred to the output and input side. Compared to the conventional active clamp technique, the

Junming Zhang; Xiucheng Huang; Xinke Wu; Zhaoming Qian

2010-01-01

14

A high efficiency Flyback converter with new active clamp technique  

Microsoft Academic Search

This paper proposes a Flyback converter with a non-complementary active clamp method. With the proposed control method, the energy in the leakage inductance can be fully recycled and the soft switching is achieved for the main switch. Compared to the conventional active clamp technique, the proposed method features high efficiency on both heavy load and light load conditions and the

Xiucheng Huang; Weijing Du; Wei Yuan; Junming Zhang; Zhaoming Qian

2010-01-01

15

High-Step-Up and High-Efficiency Fuel-Cell Power-Generation System With Active-Clamp Flyback–Forward Converter  

Microsoft Academic Search

A high-efficiency fuel-cell power-generation system with an active-clamp flyback-forward converter is presented in this paper to boost a 12-V dc voltage into a 220-V 50-Hz ac voltage. The proposed system includes a high-efficiency high-step-up inter- leaved soft-switching flyback-forward converter and a full-bridge inverter. The front-end active-clamp flyback-forward converter has the advantages of zero-voltage-switching performance for all the primary switches, reverse-recovery-problem

Wuhua Li; Lingli Fan; Yi Zhao; Xiangning He; Dewei Xu; Bin Wu

2012-01-01

16

Planar LTCC transformers for high voltage flyback converters: Part II.  

SciTech Connect

This paper is a continuation of the work presented in SAND2007-2591 'Planar LTCC Transformers for High Voltage Flyback Converters'. The designs in that SAND report were all based on a ferrite tape/dielectric paste system originally developed by NASCENTechnoloy, Inc, who collaborated in the design and manufacturing of the planar LTCC flyback converters. The output/volume requirements were targeted to DoD application for hard target/mini fuzing at around 1500 V for reasonable primary peak currents. High voltages could be obtained but with considerable higher current. Work had begun on higher voltage systems and is where this report begins. Limits in material properties and processing capabilities show that the state-of-the-art has limited our practical output voltage from such a small part volume. In other words, the technology is currently limited within the allowable funding and interest.

Schofield, Daryl (NASCENTechnology, Inc., Watertown, SD); Schare, Joshua M., Ph.D.; Slama, George (NASCENTechnology, Inc., Watertown, SD); Abel, David (NASCENTechnology, Inc., Watertown, SD)

2009-02-01

17

Efficiency characterization and optimization in flyback DC-DC converters  

Microsoft Academic Search

This paper presents efficiency characterization and optimization in conventional flyback DC-DC converters over wide ranges of operating conditions based on power loss modeling and multi-variable non-linear constrained optimization over design parameters and controller parameters. A valley switching technique is applied to reduce MOSFET turn-on switching loss in discontinuous conduction mode (DCM). An optimization procedure is formulated to minimize power loss

Sang Hee Kang; Hien Nguyen; D. Maksimovic?; I. Cohen

2010-01-01

18

Improved integrated boost-flyback high step-up converter  

Microsoft Academic Search

High step-up ratio converters for low-voltage high-current energy sources are nowadays the focus of an intensive research activity by the power electronics community, thanks to the increasing interest for renewable energy sources like those based on photovoltaic modules and fuel-cells. One interesting topology presented in literature is based on the combination of a boost section and a flyback one, featuring

G. Spiazzi; P. Mattavelli; J. R. Gazoli; R. Magalhaes; G. Frattini

2010-01-01

19

An isolated interleaved active-clamp ZVT flyback-boost converter with coupled inductors  

Microsoft Academic Search

The fundamental limitations of interleaved flyback converters for high step-up DC\\/DC applications are analyzed in this paper. A novel interleaved flyback-boost converter is derived with further modifications on the interleaved flyback converter, which extends the voltage gain and reduces the voltage stress of the switch. The active-clamp circuits are employed to recycle the leakage energy. Both the main and the

Wuhua Li; Jianjiang Shi; Min Hu; Xiangning He

2007-01-01

20

High voltage generator using boost\\/flyback hybrid converter for stun gun applications  

Microsoft Academic Search

This paper presents high voltage generator for stun gun applications. The proposed high voltage generator consists of coupled-inductor boost and flyback converters, which adopts active clamp circuit to recover energy stored in leakage inductances of coupled inductor and transformer simultaneously. With this approach, coupled-inductor boost converter can boost voltage of battery up to high output voltage for driving flyback converter,

S.-Y. Tseng; C.-M. Yang; K.-C. Wang; G.-W. Hsu

2010-01-01

21

Analysis of leakage-inductance effect on characteristics of flyback converter without right half plane zero  

Microsoft Academic Search

The conventional flyback converter has a drawback of instability occurrence due to a right-half-plane zero. We have proposed a solution to delete this RHPZ and to keep the flyback converter always stable by introducing a novel control strategy. This method is to control the holding time of transformer's magnetizing current with the fixed discharging time. As a result, its operation

Hiroto Terashi; Tamotsu Ninomiya

2003-01-01

22

Research on photovoltaic grid-connected inverter based on soft-switching interleaved flyback converter  

Microsoft Academic Search

A grid-connected photovoltaic inverter based on interleaved flyback converter and a novel control strategy with BCM and soft switching are proposed in this paper. Power rating of the inverter can be dramatically increased due to the fact that the peak rated power of each of N interleaved flyback converter is 2\\/N of the total rated power. In order to increase

Gu Jun-yin; Wu Hong-fei; Chen Guo-cheng; Xing Yan

2010-01-01

23

Analysis of leakage-inductance effect in a flyback DC-DC converter using time keeping control  

Microsoft Academic Search

Flyback DC-DC converter is often used as power supply for many electronic systems because of circuit simplicity. We have already presented novel flyback DC-DC converter with improved stability (time keeping controlled flyback converter) by using the technique of keeping inductor current constant (H.Terashi, et al.). This converter behaves as like forward converter without RHPZ (Right Half Plane Zero), therefore the

Hiroto Terashi; Tarnotsu Ninomiya

2004-01-01

24

Development of an isolated flyback converter employing boundary-mode operation and magnetic flux sensing feedback  

E-print Network

This thesis focuses on the marriage of magnetic-flux-sensing feedback and boundary-mode operation in a flyback converter to create a simple, small, low-cost, isolated, and tightly regulated power supply. Although each ...

Kenia, Mayur V. (Mayur Vasant), 1981-

2004-01-01

25

Computer Aided Analysis of a Multi-Winging Flyback Converter Including the EMI Line Filter  

Microsoft Academic Search

A two-transistor flyback-converter, originally built to be used as a measure object for measuring electromagnetic interference is thoroughly analyzed by using the circuit analysis programme KREAN. the flyback converter is operated in current-mode using the switchmode control-IC UC3842. Input voltage is 230 V mains. The output is on multiple windings with a total power of 260 W. The analysis is

Terje Rogne; Arne Steinbakk

1987-01-01

26

Soft switching interleaved active clamp flyback inverter for a photovoltaic AC module system  

Microsoft Academic Search

A soft switching interleaved active clamp flyback inverter for a photovoltaic AC module system is proposed. The proposed system includes an interleaved active clamp flyback converter and an unfolding bridge inverter. The interleaved active clamp flyback converter has the advantages of zero voltage switching (ZVS) performance for the primary switches, reverse-recovery problem alleviation for the secondary output diodes and small

Young-Ho Kim; Jun-Gu Kim; Chung-Yuen Won; Yong-Chae Jung; Tae-Won Lee

2011-01-01

27

A wide-band modeling of DC-DC two-transistor flyback converter  

Microsoft Academic Search

This paper presents results on wide-band modeling of DC-DC flyback converter. The model of converter is composed of detailed models of transformer, transistors, diodes and tracks. Parameter identification methods are based on manufacturer data sheet and externally measurable characteristics and parameters. The templates of models are written in the MAST and implemented for simulation in the SABER simulator. Validation of

Marek Turzynski; Maciej Haras; Grzegorz Kostro; Piotr Musznicki

2011-01-01

28

RC-RCD clamp circuit for ringing losses reduction in a flyback converter  

Microsoft Academic Search

An RCD clamp circuit is usually used in flyback converters, in order to limit the voltage spikes caused by leakage transformer inductance. Oscillation ringing appears due to the clamp diode, which deteriorates the converter's power rate. This brief describes this ringing phenomenon and the use of an RC-RCD clamp circuit for damping the clamp diode's oscillation. This clamp circuit is

Alenka Hren; Joze Korelic; Miro Milanovic

2006-01-01

29

A zero-current-switching PWM flyback converter with a simple auxiliary switch  

Microsoft Academic Search

A simple and effective approach of turning an isolated hard-switched converter design into a soft-switched one is presented. By adding an auxiliary winding, switch and small capacitor to the conventional pulsewidth modulation (PWM) isolated flyback converter, all switches and diodes are softly turned on and off. No extra active or passive voltage clamp circuit is needed to suppress voltage stress

Henry Shu-Hung Chung; S. Y. R. Hui; Wei-Hua Wang

1999-01-01

30

A novel variable frequency soft switching method for Flyback converter with synchronous rectifier  

Microsoft Academic Search

This paper proposes a variable frequency zero-voltage-switching (ZVS) control method for Flyback converter with synchronous rectifier. A lossless snubber capacitor is paralleled to the drain and source of primary switch to absorb the leakage inductance energy. The conventional passive clamp circuit with RCD is omitted, and no auxiliary switch or winding is needed. Synchronous rectifier is turned on additionally for

Xiucheng Huang; Weijing Du; Wei Yuan; Junming Zhang; Zhaoming Qian

2010-01-01

31

Design and Analysis of an Interleaved Flyback–Forward Boost Converter With the Current Autobalance Characteristic  

Microsoft Academic Search

An interleaved flyback-forward boost converter is proposed in this paper. The switched capacitors are used to realize the controllable voltage source function and balance the currents of the interleaved two phases without an additional current-sharing module. Voltage lift function of the switched capacitor also reduces the turns ratio of the transformers and alleviates the voltage stresses of the output diodes.

Dong Wang; Xiangning He; Jianjiang Shi

2010-01-01

32

Interleaved ZVS Flyback-Forward converter with reduced output voltage stress on secondary rectifier diodes  

Microsoft Academic Search

In this paper, a novel active clamp Flyback-Forward converter is proposed for large voltage gain and high power applications. The interleaved configuration on the primary side is employed to handle the large input current. An improved voltage doubler configuration is adopted on the secondary side to make the output diodes sustain only half of the high output voltage. Furthermore, the

Wuhua Li; Yi Zhao; Xiangning He; David Xu; Bin Wu

2011-01-01

33

Narrow pulsed electric field generator using forward \\/ flyback hybrid converters for liquid food processing  

Microsoft Academic Search

This paper presents a high pulsed electric field generator for microbial inhibition of liquid food in continuous treatment applications. The proposed pulsed electric field generator adopts forward\\/flyback hybrid converters to achieve a bidirectional narrow pulse voltage output. With this circuit structure, the proposed one can reduce voltage stresses of output diodes and switches in secondary winding of transformer, resulting in

Y.-D. Chang; S.-Y. Tseng; T.-F. Wu; H.-R. Yang

2008-01-01

34

Analysis and design considerations for EMI and losses of RCD snubber in flyback converter  

Microsoft Academic Search

The RCD snubber is usually used in flyback converter, in order to limit the voltage spikes caused by leakage inductance of the transformer. The design considerations of RCD snubber are commonly on the power losses dissipated in the snubber and the voltage spikes of the transistor. In fact, the design of RCD snubber will also affect the EMI performance of

Peipei Meng; Xinke Wu; Jianyou Yang; Henglin Chen; Zhaoming Qian

2010-01-01

35

Digital primary-side sensing and PFC control of a flyback converter  

Microsoft Academic Search

Primary-side sensing (PSS) technique can be used for the output voltage or current regulation of a flyback converter by employing an auxiliary winding for the indirect detection of output voltage and conduction period of the output rectifier diode. However, errors in the estimation of output voltage or current may be induced by the voltage drop of the secondary diode, secondary

Chih-Wei Lin; Ying-Yu Tzou

2011-01-01

36

Active voltage clamp in flyback converters operating in CCM mode under wide load variation  

Microsoft Academic Search

Active clamp topologies of low power dissipation have become a very attractive solution in order to limit overvoltages in flyback converters. Although many suitable topologies have been introduced for the case of discontinuous conduction mode (DCM), where the duty cycle value depends on the load level, in continuous conduction mode (CCM) it is more difficult to appropriately design such topologies

Nikolaos P. Papanikolaou; Emmanuel C. Tatakis

2004-01-01

37

A new modular 3-phase AC-DC flyback converter for telecommunication  

Microsoft Academic Search

A novel mode of parallel operation of a modular three-phase AC-DC flyback converter for power factor correction along with tight regulation was recently analyzed and presented. The advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost-type three-phase converter. In this paper, the detailed small signal analysis of

J. Y. Choi; J. P. Lee; I. Choy; J. H. Song; T. Y. Kim

1998-01-01

38

An isolated high step-up forward\\/flyback active-clamp converter with output voltage lift  

Microsoft Academic Search

This paper presents an isolated high step-up forward\\/flyback active-clamp converter with output voltage lift. In order to obtain high step-up voltage gain, the output voltage lift is adopted. The characteristics of the output voltage lift are similar to the forward converter in the charging mode and the flyback converter in the discharging mode. The active-clamp circuit is employed to recycle

P. H. Kuo; T. J. Liang; K. C. Tseng; J. F. Chen; S. M. Chen

2010-01-01

39

A variable frequency soft switching boost-flyback converter for high step-up applications  

Microsoft Academic Search

This paper proposes a variable frequency zero- voltage-switching (ZVS) digital controlled boost-flyback converter (BFC) to achieve high efficiency and high step-up conversion. With no auxiliary switch introduced, ZVS of the MOSFETs can be achieved and reverse-recovery of diode eliminated naturally by operating the converter in boundary- conduction-mode. With the proposed control, both soft- switching and high efficiency are achieved in

Junjun Zhang; Hongfei Wu; Yan Xing; Kai Sun; Xudong Ma

2011-01-01

40

Analysis of a high step-up ratio flyback converter with active clamp and voltage multiplier  

Microsoft Academic Search

In this paper, an isolated high step-up ratio dc-dc converter aimed to be used in interface systems between low voltage renewable energy sources, like photovoltaic panels and fuel-cells, and the utility grid is presented. The converter is based on the active clamp flyback topology with a voltage multiplier at the transformer secondary side. Such configuration, while naturally clamping the rectifier

G. Spiazzi; P. Mattavelli; A. Costabeber

2010-01-01

41

Digitally controlled active clamp interleaved flyback converters for improving efficiency in photovoltaic grid-connected micro-inverter  

Microsoft Academic Search

Flyback converters show the characteristics of current source when operating in discontinuous conduction mode (DCM) and boundary conduction mode (BCM), which makes it widely used in photovoltaic grid-connected micro-inverter. In this paper, an active clamp interleaved flyback converter operating with combination of DCM and BCM is proposed in micro-inverter to achieve zero voltage switching (ZVS) for both of primary switches

Qiong Mo; Min Chen; Zhe Zhang; Yuru Zhang; Zhaoming Qian

2012-01-01

42

High Step-Up Ratio Flyback Converter With Active Clamp and Voltage Multiplier  

Microsoft Academic Search

In this paper, an isolated high step-up ratio dc-dc con- verter aimed to be used in interface systems between low-voltage renewable energy sources, such as photovoltaic panels and fuel cells and the utility grid, is presented. The converter is based on the active clamp flyback topology with a voltage multiplier at the transformer secondary side. Such configuration, while naturally clamping

Giorgio Spiazzi; Paolo Mattavelli; Alessandro Costabeber

2011-01-01

43

An isolated ZVS\\/ZCS flyback converter using the leakage inductance of the coupled inductor  

Microsoft Academic Search

This paper describes a simple and effective way to modify an existing hard-switched flyback power converter into a circuit with zero-voltage switching (ZVS) and zero-current switching (ZCS). The key improvement is to turn the unattractive features of the coupled inductor leakage inductance and snubber capacitor into attractive ones. The coupled inductor leakage inductance and snubber are used to form a

Henry Chung; S. Y. R. Hui; W. H. Wang

1998-01-01

44

Analysis and simulation of the influence of transformer parasitics to low power high voltage output flyback converter  

Microsoft Academic Search

The influence of transformer parasitics to low power high voltage output flyback converter is analyzed by using the transformer equivalent circuit, and through the way of simulation. Its mechanism under DCM working mode is discussed from the aspect of the flow of energy, stage by stage. Based on this analysis, the theory of balanced state of the low power high

Huang Kewei; Li Jie; Hu Xiaolin; Fan Ningjun

2008-01-01

45

The effect of different winding techniques on the stray capacitances of high frequency transformers used in flyback converters  

Microsoft Academic Search

In this paper, the effect of different winding techniques on the stray capacitances of high frequency transformers used in flyback converters has been studied. Since stray capacitances are affected by winding methods, all the typical kinds of winding techniques used for these transformers and their effects on the stray capacitances were analyzed. Furthermore, some modifications were applied to the typical

Sina Emrani Saravi; Abdolhossein Tahani; Firuz Zare; Reza Ahmadi Kordkheili

2008-01-01

46

Optimizing the winding strategy of the transformer in a flyback converter  

Microsoft Academic Search

This work presents a study of the influence of the winding strategy in the parameters of the flyback transformer. A frequency and geometry dependent model generated from FEM simulations has been employed in order to study the influence of the position of the windings on the leakage energy and AC resistance. A study of the interleaving technique in the flyback

R. Prieto; J. A. Cobos; O. Garcia; R. Asensi; J. Uceda

1996-01-01

47

Analysis and experimental results of a single-stage high-power-factor electronic ballast based on flyback converter  

Microsoft Academic Search

A new single-stage high-power-factor electronic ballast based on a flyback converter is presented in this paper. The ballast is able to supply a fluorescent lamp assuring a high-input power factor for the utility line. Other features are lamp power regulation against line voltage variations and low lamp current crest factor, both assuring long lamp life. The ballast is analyzed at

Antonio J. Calleja; J. Marcos Alonso; E. Lopez; J. Ribas; J. A. Martinez; M. Rico-Secades

1999-01-01

48

Pulse Current Regenerative Resonant Snubber-Assisted Two-Switch Flyback Type ZVS PWM DC-DC Converter  

NASA Astrophysics Data System (ADS)

In this paper, a two-switch high frequency flyback transformer type zero voltage soft switching PWM DC-DC converter using IGBTs is proposed. Effective applications for this power converter can be found in auxiliary power supplies of rolling stock transportation and electric vehicles. This power converter is basically composed of two active power switches and a flyback high frequency transformer. In addition to these, two passive lossless snubbers with power regeneration loops for energy recovery, consisting of a three winding auxiliary high frequency transformer, auxiliary capacitors and diodes are introduced to achieve zero voltage soft switching from light to full load conditions. Furthermore, this power converter has some advantages such as low cost circuit configuration, simple control scheme and high efficiency. Its operating principle is described and to determine circuit parameters, some practical design considerations are discussed. The effectiveness of the proposed power converter is evaluated and compared with the hard switching PWM DC-DC converter from an experimental point of view and the comparative electromagnetic conduction and radiation noise characteristics of both DC-DC power converter circuits are also depicted.

Inaba, Claudio Y.; Konishi, Yoshihiro; Nakaoka, Mutsuo

49

Utilization of an active-clamp circuit to achieve soft switching in flyback converters  

Microsoft Academic Search

Flyback derived power convertor topologies are attractive because of their relative simplicity when compared with other topologies used in low power applications. Incorporation of active-clamp circuitry into the flyback topology serves to recycle transformer leakage energy while minimizing switch voltage stress. The addition of the active-clamp circuit also provides a mechanism for achieving zero-voltage-switching (ZVS) of both the primary and

R. Watson; F. C. Lee; G. C. Hua

1996-01-01

50

Utilization of an active-clamp circuit to achieve soft switching in flyback converters  

Microsoft Academic Search

Flyback derived topologies are attractive because of their relative simplicity when compared with other topologies used in low power applications. Incorporation of active-clamp circuitry into the flyback topology serves to recycle transformer leakage energy while minimizing switch voltage stress. The addition of the active-clamp circuit also provides a mechanism for achieving zero-voltage-switching (ZVS) of both the main and auxiliary-switches. ZVS

R. Watson; F. C. Lee; G. C. Hua

1994-01-01

51

Flyback Transformer Based Transient Suppression Method for Digitally Controlled Buck Converters  

E-print Network

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

Prodiæ, Aleksandar

52

A modified topology of isolated interleaved flyback boost converter with Winding-Cross-Coupled inductors  

Microsoft Academic Search

This paper presents a new topology of Isolated Interleaved Boost Converter with Winding-Cross-Coupled Inductors (WCCIs) that reduces the switching losses. Primitive structure has active clamp circuit that is used to obtain zero voltage switching (ZVS) operation for two main switches during the whole switching transition but the clamp switch itself has high switching losses. In this paper, the clamp switch

Karim Abbaszadeh; Mohsen Yazdaninejad

2010-01-01

53

The New Bridge Converter Control Method  

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

54

A comparison of half-bridge resonant converter topologies  

Microsoft Academic Search

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

R. L. Steigerwald

1988-01-01

55

A Three-in-One Converter for Regular and Emergency Lighting Applications  

Microsoft Academic Search

This paper presents a three-in-one converter for regular and emergency lighting applications. The converter can function as regular ballast, emergency ballast, and battery charger\\/discharger, achieving regular and emergency lighting features. The three-in-one converter used in the ballast is an integration of a bidirectional flyback converter and two half-bridge series-resonant parallel-loaded inverters. The derivation and operating principle of the proposed converter

Yung-Chun Wu; Yu-Kai Chen

2009-01-01

56

ZVS Bridge Leg and ZCS Bridge Leg DC-DC Converter with Tapped Inductor Filter  

NASA Astrophysics Data System (ADS)

In this paper, a novel full-bridge soft-switching phase-shifted PWM DC-DC power converter circuit is presented. A tapped inductor filter is implemented in the proposed converter topology to achieve soft switching commutation for the active power switches under wide load variation range, to minimize circulating current without using additional resonant circuit and/or auxiliary switching devices. The effectiveness of the proposed soft-switching DC-DC power converter is verified in experiment with 2kW-100kHz breadboard circuit using IGBTs.

Moisseev, Serguei; Hamada, Satoshi; Nakaoka, Mutsuo

57

Low Cost Embedded Controlled Full Bridge LC Parallel Resonant Converter  

NASA Astrophysics Data System (ADS)

In this paper the converter requirements for an optimum control of an electrolyser linked with a DC bus are analyzed and discussed. An electrolyser is a part of renewable energy system which generates hydrogen from water electrolysis. The hydrogen generating device is part of a complex system constituted by a supplying photovoltaic plant, the grid and a fuel cell battery. The characterization in several operative conditions of an actual industrial electrolyser is carried out in order to design and optimize the DC/DC converter. A dedicated zero voltage switching DC/DC converter is presented and simulated inside the context of the distributed energy production and storage system. The proposed supplying converter gives a stable output voltage and high circuit efficiency in all the proposed simulated scenarios. The adopted DC/DC converter is realized in a full-bridge topology technique in order to achieve zero voltage switching for the power switches and to regulate the output voltage. This converter has advantages like high power density, low EMI and reduced switching stresses. The simulation results are verified with the experimental results.

Chandrasekhar, P.; Reddy, S.

2009-01-01

58

Half Bridge Boost Converter for Power Quality Improvement in PMBLDCM Drive  

Microsoft Academic Search

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

Bhim Singh; Sanjeev Singh

2009-01-01

59

Power sharing analysis of double-input converters based on H-bridge cells  

Microsoft Academic Search

This paper concludes the previous works on the synthesis of double input converters based on H-bridge cells. First it derives a new double input converter topology called the boost-boost converter based on cascaded H-bridge cells. Next it presents a thorough power sharing analysis of the H-bridge based double input converters. Finally, it provides simulation results to support the theoretical outcomes.

Reza Ahmadi; Nima Yousefpoor; Mehdi Ferdowsi

2011-01-01

60

Single phase unity power factor control for dual active bridge converter  

Microsoft Academic Search

An AC line fed switching power supply with a single power converter stage is described which operates with high input power factor while maintaining good regulation of the desired output DC voltage. The single-power converter is a dual active bridge DC-to-DC power converter (DABC), comprising high-frequency transformer-coupled input and output bridge converters. The DABC receives a rectified AC line voltage

M. H. Kheraluwala; R. W. De Doncker

1993-01-01

61

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

Microsoft Academic Search

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

Sanjeev Singh; Bhim Singh

2010-01-01

62

An active-clamp snubber for isolated half-bridge DC-DC converters  

Microsoft Academic Search

In the conventional isolated half-bridge DC-DC converter, the leakage-inductance-related losses degrade the converter efficiency and limit the increase of the converter switching frequency. A novel active-clamp circuit is proposed to recycle the energy stored in the leakage inductance and thus improves the converter efficiency. By transferring the energy in the leakage inductance to a capacitor, the leakage inductance energy is

Hong Mao; Songquan Deng; J. A. Abu-Qahoup; Yangyang Wen; Issa Batarseh

2003-01-01

63

Temperature compensation of Wheatstone bridge magnetoresistive sensors based on generalized impedance converter with input reference current  

NASA Astrophysics Data System (ADS)

A compensation method of the sensitivity drift of the Wheatstone bridge sensor is proposed. The technique was carried out by placing a temperature sensor and the bridge to be compensated inside a generalized impedance converter with input reference current. No internal modification of the bridge arms is required so that the circuit is capable to compensate practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a commercial magnetoresistive bridge sensor.

Ramírez Muñoz, Diego; Sánchez Moreno, J.; Casans Berga, Silvia; Castro Montero, Enrique; Reig Escrivà, Càndid; Navarro Antón, A. Edith

2006-10-01

64

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

Microsoft Academic Search

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

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

1992-01-01

65

Pseudo-resonant full bridge DC\\/DC converter  

Microsoft Academic Search

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

O. D. Patterson; D. M. Divan

1991-01-01

66

Experimental studies and computer simulation of the control of energy transfer using inductor-converter bridges  

SciTech Connect

An inductor-converter bridge (ICB) is a solid state DC-AC-DC power converter system for bidirectional, controllable, energy transfer between two coils. The ICB is suitable for supplying large pulsed power to such magnets as the superconducting equilibrium field coil of the proposed tokamak power reactors from another superconducting energy storage coil.

Hirano, M.; Kustom, R.L.

1984-03-01

67

A self oscillated half bridge converter using impulse resonant soft-switching  

Microsoft Academic Search

A novel circuit of DC-TO-DC converter for the battery charger of telecommunication equipment is proposed. For the circuit, a novel self oscillated half-bridge converter with an impulse resonant soft-switching using saturating inductance of the oscillator is developed. In this converter, the self oscillated frequency control circuit has the switches operated soft-switching by impulse charging and discharging the parasitic capacitance of

H. Sakamoto; K. Harada; C. H. Kang; Y. Matsuda; H. J. Kim

2002-01-01

68

Power Quality Improvement of PMBLDCM Driven Air-Conditioner Using a Single-Stage PFC Boost Bridge Converter  

Microsoft Academic Search

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

Sanjeev Singh; Bhim Singh

2009-01-01

69

Radiation Effects on DC-DC Converters  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

70

Handheld Flyback driven coaxial dielectric barrier discharge: Development and characterization  

SciTech Connect

The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10-33 W to generate a 1.2-1.6 kV 3.5 {mu}s pulse. An argon discharge breakdown voltage of {approx}768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5-10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in the volume discharge increases linearly at a rate of 75{+-}20% mW/cm{sup 3} per 1 slm of gas. Electrical power transfer efficiency between the secondary Flyback coil and the discharge volume increases from 0.1% to 0.65%. Neutral argon gas forced convection analysis yields a similar energy loss rate to the electrical discharge process. Optical emission spectroscopy studies of the expanding discharge plume into ambient air reveal that the air climatically controls the plume chemistry to produce an abundance of neutral argon atoms and molecular nitrogen.

Law, V. J. [National Center of Plasma Science and Technology (NCPST), Dublin City University, Dublin 9 (Ireland); Milosavljevic, V. [School of Physics and NCPST, Dublin City University, Dublin 9, Ireland and Faculty of Physics, University of Belgrade, P.O. Box 368, Belgrade (Serbia); O'Connor, N.; Daniels, S. [School of Electronic Engineering and NCPST, Dublin City University, Dublin 9 (Ireland); Lalor, J. F. [NCPST, Dublin City University, Dublin 9 (Ireland)

2008-09-15

71

Handheld Flyback driven coaxial dielectric barrier discharge: Development and characterization.  

PubMed

The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10-33 W to generate a 1.2-1.6 kV 3.5 micros pulse. An argon discharge breakdown voltage of approximately 768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5-10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in the volume discharge increases linearly at a rate of 75+/-20% mW/cm(3) per 1 slm of gas. Electrical power transfer efficiency between the secondary Flyback coil and the discharge volume increases from 0.1% to 0.65%. Neutral argon gas forced convection analysis yields a similar energy loss rate to the electrical discharge process. Optical emission spectroscopy studies of the expanding discharge plume into ambient air reveal that the air climatically controls the plume chemistry to produce an abundance of neutral argon atoms and molecular nitrogen. PMID:19044446

Law, V J; Milosavljevi?, V; O'Connor, N; Lalor, J F; Daniels, S

2008-09-01

72

Discussion on the control method of the inductor-converter bridge by simulation and experiment  

SciTech Connect

With the development of the superconducting magnet as an energy storage unit, pulsed power loads between superconducting magnets of increasing magnitude up to several hundred megawatts or more appear within the realm of possibility. An energy storage unit that is independent of the power grid can be used in applications where the pulsed power required from the power grid may cause a hazardous effect on the power system. An energy transfer system between the storage and the load units eliminates the disturbance on the power grid. An inductor-converter bridge is proposed for such a purpose. The inductor-converter bridge (ICB) is a solid state DC-AC-DC converter system for reversible energy transfer between two high-inductance inductors. The converter thyristors are naturally commutated by a set of wye-connected capacitors on the AC lines of the circuit. The circuit is designed so that, in every converter cycle, a very small fraction of the magnet energy is stored in these capacitors. The characteristics of the inductor-converter bridge are briefly summarized as follows: low energy loss, reversibility of the energy transfer direction, controllability of the energy transfer rate, and no conversion to another energy form.

Hirano, M.; Kustom, R.L.

1983-07-01

73

Novel zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converter using coupled output inductor  

Microsoft Academic Search

A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed. The new converter improves the drawbacks of the previously proposed ZVZCS FB PWM converters. A simple auxiliary circuit with neither lossy components nor active switches achieves ZVZCS of the primary switches. Since the proposed converter has many advantages such as simple auxiliary circuit, high

Hang-Seok Choi; J. W. Kim; B. H. Cho

2001-01-01

74

Novel zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converter using coupled output inductor  

Microsoft Academic Search

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width-modulated (PWM) converter is proposed to improve the previously proposed ZVZCS full-bridge PWM converters. By employing a simple auxiliary circuit with neither lossy components nor active switches, soft-switching of the primary switches is achieved. The proposed converter has many advantages such as simple auxiliary circuit, high efficiency, low voltage stress of the rectifier

Hang-Seok Choi; Jung-Won Kim; Bo Hyung Cho

2002-01-01

75

Performance characterization of a high power dual active bridge DC\\/DC converter  

Microsoft Academic Search

The analysis, control, and performance of a high-power, high-power-density DC\\/DC power converter that is based on the single-phase dual active bridge topology is described. For high-output voltages, on the order of kilovolts, a cascaded output structure is considered. The impact of snubber capacitance and magnetizing inductance on the soft switching region and various control strategies are discussed. Computer simulation results

M. H. Kheraluwala; R. W. Gasgoigne; D. M. Divan; E. Bauman

1990-01-01

76

A modular power electronic transformer based on a cascaded H-bridge multilevel converter  

Microsoft Academic Search

In this paper a modular power electronic transformer (PET) for feeding critical loads is presented. The PE-based transformer is a multi-cellular step-down converter that can directly connect to medium voltage levels on the primary side and provide a low voltage, highly stable interface for consumer applications. The presented structure consists of three stages: a cascaded H-bridge (CHB) rectifier, an isolation

H. Iman-Eini; Sh. Farhangi; J.-L. Schanen; M. Khakbazan-Fard

2009-01-01

77

Performance evaluation of half-bridge cascaded multilevel converters operated with multicarrier sinusoidal PWM techniques  

Microsoft Academic Search

High-power high-voltage power electronics systems with fully-controlled semiconductors can benefit from the development of modular solutions based on voltage-sourced building blocks. This paper offers a performance comparison of various multicarrier sinusoidal pulse width modulation (PWM) techniques for the control of the modular multilevel converter (MMC) based on the half-bridge capacitor cell. It is found that the PWM method can significantly

Georgios S. Konstantinou; Vassilios G. Agelidis

2009-01-01

78

Voltage Oscillation Reduction Technique for Phase-Shift Full-Bridge Converter  

Microsoft Academic Search

A conventional phase-shift full-bridge (PSFB) converter has a serious voltage oscillation problem across the secondary rectifier diodes. To overcome this problem, a new voltage oscillation reduction technique (VORT), which effectively reduces the rectifier voltage oscillation by a simple nondissipative manner, is proposed. The concept of VORT is to utilize the operation of leading-leg transition, which does not cause severe rectifier

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

2007-01-01

79

High-voltage, high-power, ZVS, full-bridge PWM converter employing an active snubber  

Microsoft Academic Search

The authors present the analysis, design, and applications of a high-voltage, high-power, zero-voltage switched (ZVS), full-bridge (FB) pulse-width-modulated (PWM) converter with an active snubber in the secondary circuit. The nondissipative snubber completely eliminates the voltage overshoot and ringing across the rectifiers. The ringing of the parasitic capacitance of the rectifiers and the leakage inductance of the transformer are eliminated in

J. A. Sabate; V. Vlatkovic; R. B. Ridley; F. C. Lee

1991-01-01

80

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

E-print Network

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

Dr. M. Sridhar; Sayed Baji Shaik

81

Novel Full-bridge ZVS DC-DC Converter with an Clamp Diodes  

NASA Astrophysics Data System (ADS)

The two arms of this converter all work at zero-voltage switching condition, that bring many advantages, such as little loss of power, simple control, etc. But these also exists some problems, such as parasitic oscillation on the output rectifier diodes. A novel full-bridge ZVS PWM DC-DC converter which adopts two clamping diodes in the first side of the transformer is proposed to reduce the parasitic oscillation in this paper. In this paper, It heavily analyzes the realization process of their soft-switching and the reason of related issues and solution, we establishes simulation model and simulates using orCAD. Finally,a 5 kW ZVS PWM DC-DC converter Prototype in that TMS320F2812 is the core controlled chip has been set up, and the experiments showed us the validation of the correlative theory.

Guangqun, Nan; Xue, Hu

82

Soft-switching PWM full-bridge DC-DC converter with energy recovery transformer and auxiliary passive lossless snubbers  

Microsoft Academic Search

This paper proposes a novel soft-switching full-bridge PWM DC-DC converter using passive regenerative snubber. The newly proposed circuit topology is composed of a full-bridge converter with a high frequency linked transformer and passive snubbers configured with energy regenerative circuit and controlled under the conventional PWM actions to prevent freewheeling current. The leakage inductance of main transformer (Tm) helps to achieve

Yung-Fu Huang; Chih-Wen Liu; Yoshihiro Konishi

2007-01-01

83

ZVS Full-Bridge Based DC-DC Converter with Linear Voltage Gain According to Duty Cycle  

NASA Astrophysics Data System (ADS)

This paper presents a zero-voltage-switching (ZVS) full-bridge based DC-DC converter with linear voltage gain according to duty cycle. The proposed converter is based on an asymmetrical pulse-width-modulation (APWM) full-bridge converter which has various advantages over other converters. However, it has some drawbacks such as limited maximum duty cycle to 0.5 and narrow input range. The proposed converter overcomes these problems. The duty cycle is not limited and input voltage range is wide. Also, the ZVS operation of all power switches is achieved. Therefore, switching losses are significantly reduced and high-efficiency is obtained. Steady-state analysis and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter.

Do, Hyun-Lark

2013-09-01

84

Development of a digital solar simulator based on full-bridge converter  

NASA Astrophysics Data System (ADS)

With the development of solar photovoltaic, distribution schemes utilized in power grid had been commonly application, and photovoltaic (PV) inverter is an essential equipment in grid. In this paper, a digital solar simulator based on full-bridge structure is presented. The output characteristic curve of system is electrically similar to silicon solar cells, which can greatly simplify research methods of PV inverter, improve the efficiency of research and development. The proposed simulator consists on a main control board based on TM320F28335, phase-shifted zero-voltage-switching (ZVS) DC-DC full-bridge converter and voltage and current sampling circuit, that allows emulating the voltage-current curve with the open-circuit voltage (Voc) of 900V and the short-circuit current (Isc) of 18A .When the system connected to a PV inverter, the inverter can quickly track from the open-circuit to the maximum power point and keep stability.

Liu, Chen; Feng, Jian; Liu, Zhilong; Tong, Weichao; Ji, Yibo

2014-02-01

85

"Forback" Dc-To-Dc Converters  

NASA Technical Reports Server (NTRS)

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

Lukemire, Alan T.

1992-01-01

86

Zero-voltage and zero-current-switching full bridge PWM converter for high-power applications  

Microsoft Academic Search

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse-width modulated (PWM) converter is proposed. The new converter overcomes the limitations of the zero-voltage-switching (ZVS)-FB-PWM converter, such as high circulating energy, loss of duty cycle, and limited ZVS load range for the lagging-leg switches. By using the DC blocking capacitor and adding a saturable inductor, the primary current during the freewheeling

Jung-Goo Cho; J. A. Sabate; Guichao Hua; Fred C. Lee

1996-01-01

87

Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier  

PubMed Central

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500?W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

88

A Novel Half-Bridge Asymmetrical ZCS-PWM DC-DC Converter with High Frequency-Link  

NASA Astrophysics Data System (ADS)

A novel zero current soft-switching (ZCS)-PWM cell-assisted half-bridge DC-DC converter topology with a high frequency link is proposed in this paper. The newly-proposed DC-DC converter consists of a PWM-controlled single-ended half-bridge high frequency (HF) inverter and a current doubler rectifier linked with a HF transformer. In order to attain the wide range of ZCS-PWM operation in the primary-side HF inverter, an active edge resonant snubber cell composed by a switched capacitor and a lossless inductor is adopted in the half-bridge leg, providing ZCS commutation for a wide range of output power. The operation characteristics of the DC-DC converter proposed here are described, and its feasibility data is demonstrated and evaluated with simulation and experimental results.

Mishima, Tomokazu; Hiraki, Eiji; Tanaka, Toshihiko; Nakaoka, Mutsuo

89

Redesign of the H-Bridge Switch Plate of the SNS High Voltage Converter Modulator  

SciTech Connect

The 1-MW High Voltage Converter Modulators [1] have operated in excess of 250,000 hours at the Spallation Neutron Source. Increased demands on the accelerator performance require increased modulator reliability. An effort is underway at SLAC National Accelerator Laboratory to redesign the modulator H-bridge switch plate with the goals of increasing reliability and performance [2]. The major difference between the SLAC design and the existing design is the use of press-pack IGBTs. Compared to other packaging options, these IGBTs have been shown to have increased performance in pulsed-power applications, have increased cooling capability, and do not fragment and disassemble during a fault event. An overview of the SLAC switch plate redesign is presented. Design steps including electrical modeling of the modulator and H-bridge, development of an integrated IGBT clamping mechanism, and fault tests are discussed. Experimental results will be presented comparing electrical performance of the SLAC switch plate to the existing switchplate under normal and fault conditions.

Kemp, M.A.; Burkhart, C.; Nguyen, M.N.; /SLAC; Anderson, D.E.; /Oak Ridge

2009-05-07

90

Control scheme of three-level H-bridge converter for interfacing between renewable energy resources and AC grid  

Microsoft Academic Search

This paper presents a control strategy of multilevel converters for integration of renewable energy resources into power grid. The proposed technique provides compensation for active, reactive, and harmonic current components of grid-connected loads. A three-level H-bridge converter is proposed as the interfacing system between renewable energy resources and utility grid. High performance of the proposed technique is indicated with injection

Edris Pouresmaeil; Daniel Montesinos-Miracle; Oriol Gomis-Bellmunt

2011-01-01

91

Phase-shifted PWM full-bridge DC-DC converters for automotive applications: reduction of ringing voltages  

Microsoft Academic Search

This work analyzes two solutions for ringing voltage problems occurring in the output voltage of a zero-voltage and zero-current switching phase-shifted pulsewidth modulation full-bridge DC-DC converter intended for automotive applications. An RCD snubber and an active snubber (thereafter called \\

A. Jangwanitlert; J. C. Balda

2004-01-01

92

Bridges  

NSDL National Science Digital Library

Bridges come in a wide variety of sizes, shapes, and lengths and are found all over the world. It is important that bridges are strong so they are safe to cross. Design and build a your own model bridge. Test your bridge for strength using a force sensor that measures how hard you pull on your bridge. By observing a graph of the force, determine the amount of force needed to make your bridge collapse.

Consortium, The C.

2012-05-21

93

An Alternative Energy Recovery Clamp Circuit for Full-Bridge PWM Converters With Wide Ranges of Input Voltage  

Microsoft Academic Search

A full-bridge DC-DC converter employing a diode rectifier in the output experiences a severe voltage overshoot and oscillation problem across the diode rectifier caused by interaction between junction capacitance of the rectifier diode and leakage inductance of the transformer. The pronounced reverse-recovery current of high-power diodes significantly contributes to these issues by increasing power lossand voltage overshoot. Conventional energy recovery

Honnyong Cha; Lihua Chen; Rongjun Ding; Qingsong Tang; Fang Zheng Peng

2008-01-01

94

Three-level half-bridge ZVS DC\\/DC converter for electrolyzer integration with renewable energy systems  

Microsoft Academic Search

This paper presents findings of a R&D project tar geted to the development of a galvanically isolated step-down DC\\/DC converter for electrolyzer integration with renewable energy systems. The topology proposed is a three-level neutral point clamped half-bridge with a high-frequency isolation transformer and a current doubler rectifier that fulfils all the targets set by the designers. Despite an increased component

Anna Andrijanovits; Dmitri Vinnikov; Indrek Roasto; Andrei Blinov

2011-01-01

95

Cascaded H-bridge multilevel converter for grid connected photovoltaic generators with independent maximum power point tracking of each solar array  

Microsoft Academic Search

This paper introduces a new control method and proportional PWM modulation of the cascaded H-bridge multilevel converter for grid-connected photovoltaic systems. This control makes each H-bridge module supply different power levels, allowing therefore for each module an independent maximum power point tracking of the corresponding photovoltaic array.

O. Alonso; P. Sanchis; E. Gubia; L. Marroyo

2003-01-01

96

Bridges  

NSDL National Science Digital Library

Through a five-lesson series that includes numerous hands-on activities, students are introduced to the importance and pervasiveness of bridges for connecting people to resources, places and other people, with references to many historical and current-day examples. In learning about bridge typesâarch, beam, truss and suspensionâstudents explore the effect of tensile and compressive forces. Students investigate the calculations that go into designing bridges; they learn about loads and cross-sectional areas by designing and testing the strength of model piers. Geology and soils are explored as they discover the importance of foundations, bearing pressure and settlement considerations in the creation of dependable bridges and structures. Students learn about brittle and ductile material properties. Students also learn about the many cost factors that comprise the economic considerations of bridge building. Bridges are unique challenges that take advantage of the creative nature of engineering.

Integrated Teaching And Learning Program

97

Ac-Ac Dual Active Bridge Converter for Solid State Transformer  

E-print Network

is required at some stage of power conversion. A high frequency transformer is preferred to reduce the weight network to convert the source ac voltage to an intermediate high frequency ac voltage and another switching network to convert the high frequency voltage back to grid frequency. Bi-directional power flow

Kimball, Jonathan W.

98

Multiphase Bidirectional Flyback Converter Topology for Hybrid Electric Vehicles  

Microsoft Academic Search

For hybrid electric vehicles, the batteries and the drive dc link may be at different voltages. The batteries are at low voltage to obtain higher volumetric efficiencies, and the dc link is at higher voltage to have higher efficiency on the motor side. Therefore, a power interface between the batteries and the drive's dc link is essential. This power interface

Tanmoy Bhattacharya; V. Shriganesh Giri; K. Mathew; L. Umanand

2009-01-01

99

Converter  

NSDL National Science Digital Library

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

2010-01-01

100

H-bridge multilevel voltage source converter for direct grid connection of renewable energy systems  

Microsoft Academic Search

The conventional approach based on low-voltage converter with power frequency transformer is commonly employed for grid connection of offshore renewable power generation systems. Because of the heavy weight and large size of the transformer, the system can be expensive and complex for installation and maintenance. As an alternative approach to achieve a compact and light direct grid connection, a high-voltage

M. R. Islam; Y. G. Guo; J. G. Zhu

2011-01-01

101

Bridges  

MedlinePLUS

... mouth where there is a lot of biting force. They also may not be the best choice if the wings will have to be small to avoid getting in the way of the bite or the gums. Getting a bridge requires at ...

102

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

103

Analysis, optimized design and adaptive control of a ZCS full-bridge converter without voltage over-stress on the switches  

Microsoft Academic Search

This paper presents the analysis and design of a new current-driven soft-switched full-bridge converter, in which all main switches are zero-current-switched (ZCS), and the switches in a switched-capacitor snubber are zero-voltage-switched (ZVS). For each value of the supply and load, the snubber capacitor is adaptively charged at the minimum necessary value for assuring soft-switching; thus, less resonant energy is circulated.

Xin Zhang; Henry Shu-hung Chung; Xinbo Ruan; Adrian Ioinovici

2010-01-01

104

A high-frequency 1.5 MVA H-bridge building block for cascaded multilevel converters using emitter turn-off thyrister  

Microsoft Academic Search

This paper proposes a 1.5 MVA H-bridge building block (HBBB) using the newly developed emitter turn-off (ETO) thyristor to demonstrate the superior performance of the ETO. The modular HBBB is intended to be used in high-power cascaded multilevel voltage source converters for reactive power compensation applications. Because of theirs identical layouts, the HBBB are easily manufactured for both the building

Siriroj Sirisukprasert; Zhenxue Xu; Bin Zhang; Jason Lai; Alex Q. Huang

2002-01-01

105

Liquid flyback booster pre-phase: A study assessment  

NASA Technical Reports Server (NTRS)

The concept of a flyback booster has been around since early in the shuttle program. The original two-stage shuttle concepts used a manned flyback booster. These boosters were eliminated from the program for funding and size reasons. The current shuttle uses two Redesigned Solid Rocket Motors (RSRM's), which are recovered and refurbished after each flight; this is one of the major cost factors of the program. Replacement options have been studied over the past ten years. The conclusion reached by the most recent study is that the liquid flyback booster (LFBB) is the only competitive option from a life-cycle cost perspective. The purpose of this study was to assess the feasibility and practicality of LFBB's. The study provides an expansion of the recommendations made during the aforementioned study. The primary benefits are the potential for enhanced reusability and a reduction of recurring costs. The potential savings in vehicle turnaround could offset the up-front costs. Development of LFBB's requires a commitment to the shuttle program for 20 to 30 years. LFBB's also offer enhanced safety and abort capabilities. Currently, any failure of an RSRM can be considered catastrophic, since there are no intact abort capabilities during the burn of the RSRM's. The performance goal of the LFBB's was to lift a fully loaded orbiter under optimal conditions, so as not to be the limiting factor of the performance capability of the shuttle. In addition, a final benefit is the availability of growth paths for applications other than shuttle.

Peterson, W.; Ankney, W.; Bell, J.; Berning, M.; Bryant, L.; Bufkin, A.; Cain, L.; Caram, J.; Cockrell, B.; Curry, D.

1994-01-01

106

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

E-print Network

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

C. B. Saravanan; G. Devanatha Reddy

107

Isolated ZVT boost converter with switched capacitors and coupled inductors  

Microsoft Academic Search

An interleaved and isolated boost converter with switched capacitors is proposed in this paper. The switched capacitors are used to realize the inherent voltage-lift function which increases the voltage gain and reduces the turns ratio of the transformers greatly. Because the transformers can operate in flyback and forward modes which make part of the output energy stored in the switched

Dong Wang; Yan Deng; Xiangning He

2008-01-01

108

Surge analysis of current-mode resonant converter  

Microsoft Academic Search

Noise characteristics at output stage in a current-mode resonant flyback converter has been quantitatively studied by experiment and analysis. The influence of parasitic elements such as parasitic inductance and stray capacitance in a rectifying diode, smoothing capacitor and transformer on noise generation is clarified

Toru HIGASHI; H. Tsuruta; M. Nakahara

1997-01-01

109

Konigsberg Bridge  

NSDL National Science Digital Library

The webpage provides an overview of how the Konigsberg Bridge problem led Euler to develop graph theory and establish the basis for topology. The page includes links to images of the bridge. It also includes an animated image which converts the map of Konigsberg into a graph.

2010-07-30

110

Design considerations for high-voltage high-power full-bridge zero-voltage-switched PWM converter  

Microsoft Academic Search

A steady-state analysis is presented with complete characterization of the converter operation. A small-signal model of the converter is established. The design procedures based on the analysis are presented and the various losses in the circuit assessed. Critical design considerations for a high-power, high-voltage application are analyzed. The results of the analysis are verified using a high-voltage. 2 kW prototype

J. A. Sabate; V. Vlatkovic; R. B. Ridley; F. C. Lee; B. H. Cho

1990-01-01

111

Performance analysis of isolated ZVT interleaved converter with winding-cross-coupled inductors and switched-capacitors  

Microsoft Academic Search

In this paper, a third winding and an additional switched capacitor are inserted into each phase of the conventional interleaved Flyback converter to derive a novel triple boost converter for high step-up conversion. Furthermore, the active clamp circuit, which is composed of a power MOSFET and a small capacitor, is inserted to the primary side of each phase to recycle

Rui Xie; Wuhua Li; Yi Zhao; Jing Zhao; Xiangning He; Fengwen Cao

2010-01-01

112

IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 22, NO. 2, MARCH 2007 461 Current-Fed Dual-Bridge DCDC Converter  

E-print Network

­DC Converter Wei Song, Member, IEEE, and Brad Lehman, Member, IEEE Abstract--A new isolated current., Shanghai 200241, China (e-mail: wsong@ece.neu.edu; wayne.song@intel.com). B. Lehman is with the Department

Lehman, Brad

113

Digital Bridges: Bridges of the Nineteenth Century  

NSDL National Science Digital Library

The collection consists of thirty representative 19th-century American bridge engineering monographs, manuals, and documents from the Lehigh University Libraries' Special Collections. The source documents have been scanned, converted to text, and partially corrected to make all significant terms and personal and proper names retrievable through the site's search engine. Topics include specific bridges (the Brooklyn Bridge, the East River Bridge), bridge types (suspension bridges, wrought iron bridges), bridge components (cabling, foundations), bridge design, bridge disasters, and others. The collection is browseable by title and searchable by keyword. Printable versions of the documents are also available. A glossary is also provided with definitions of terms, short biographies of authors, and descriptions of some of the bridges

2002-01-01

114

Transient analysis and control of bias magnetic state in the transformer of on-line pulse-width-modulation switching full bridge direct current-direct current converter  

NASA Astrophysics Data System (ADS)

This paper presents a finite element analysis (FEA) based method for analyzing and controlling the bias magnetic state of the transformer of a pulse-width-modulation (PWM) switching full bridge dc-dc converter. A field-circuit indirect coupling method for predicting the transient bias magnetic state is introduced first. To increase flexibility of the proposed method, a novel transformer model which can address not only its basic input-output characteristic, but also the nonlinear magnetizing inductance, is proposed. Both the asymmetric characteristic and the variable laws of the current flowing through the two secondary windings during the period of PWM switching-off state are highlighted. Finally, the peak magnetizing current controlled method based on the on-line magnetizing current computation is introduced. Analysis results show that this method can address the magnetic saturation at winding ends, and hence many previous difficulties, such as the start-up process and asymmetry of power electronics, can be easily controlled.

Chen, Jiaxin; Guo, Youguang; Zhu, Jianguo; Wei Lin, Zhi

2012-04-01

115

A novel soft-switching full-bridge DC\\/DC converter: analysis, design considerations, and experimental results at 1.5 kW, 100 kHz  

Microsoft Academic Search

The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulsewidth modulated) full-bridge DC\\/DC converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors give analyses, practical design considerations, and experimental results for a 1.5 kW converter with 60 V, 25 A output, operating at 100

R. Redl; N. O. Sokal; L. Balogh

1991-01-01

116

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

Microsoft Academic Search

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

Wuhua Li; Xiangning He

2008-01-01

117

Full bridge converter Transformers and isolated converters  

E-print Network

A transformer consists of two or more coils that are magnetically coupled (a common magnetic flux flows through: the current of the inductor, is the voltage from the left side of the inductor to the middle tap, no energy is accumulated in the inductor, hence the time integral of the inductor voltage over one switching

Knobloch,Jürgen

118

Interleaved power converter  

DOEpatents

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

Zhu, Lizhi (Canton, MI)

2007-11-13

119

Advanced High Power DC-DC Converter using A Novel Type Voltage Source Full-Bridge Soft-Switching PWM Inverter with High Frequency Transformer Link for Arc Welding Applications  

NASA Astrophysics Data System (ADS)

This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.

Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo

120

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

Microsoft Academic Search

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

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

2009-01-01

121

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

Microsoft Academic Search

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

Jingquan Chen; Dragan MaksimoviC; Robert Erickson

2001-01-01

122

Volume optimization of a PFC flyback structure under electromagnetic compatibility, loss and temperature constraints  

Microsoft Academic Search

The aim of this paper is to present an analytical optimization approach of a flyback structure in PFC mode. Indeed, softwares like Saber, Pspice or Simplorer are effective means for the power electronics structure time-domain studies. However, if these structures have an AC input and a high switching frequency (various time scales), time-domain simulation becomes painful and expensive in memory

C. Larouci; J. P. Ferrieux; L. Gerbaud; J. Roudet; J. P. Keradec

2002-01-01

123

Flyback Inverter Controlled by Sensorless Current MPPT for Photovoltaic Power System  

Microsoft Academic Search

This paper presents a flyback inverter controlled by sensorless current maximum power point tracking (MPPT) for a small photovoltaic (PV) power system. Although the proposed system has small output power such as 300 W, a few sets of small PV power systems can be easily connected in parallel to yield higher output power. When a PV power system is constructed

N. Kasa; T. Iida; L. Chen

2005-01-01

124

High-efficiency grid-connected photovoltaic module integrated converter system with high-speed communication interfaces for small-scale distribution power generation  

SciTech Connect

This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DC converter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DC converter. The proposed step-up DC-DC converter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, for centralized power control of distributed PV MIC systems, a PV power control scheme with both a central control level and a local control level is presented. The central PV power control level controls the whole power production by sending out reference power signals to each individual PV MIC system. The proposed step-up DC-DC converter achieves a high-efficiency of 97.5% at 260 W output power to generate the DC-link voltage of 350 V from the PV voltage of 36.1 V. The PV MIC system including the DC-DC converter and the DC-AC inverter achieves a high-efficiency of 95% with the PV current ripple less than 3% variation of the rated PV current. (author)

Choi, Woo-Young; Lai, Jih-Sheng (Jason) [Future Energy Electronics Center, Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA (United States)

2010-04-15

125

Boost Converter Animation  

NSDL National Science Digital Library

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

2009-11-06

126

Discontinuous Buck Converter  

NSDL National Science Digital Library

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

2009-11-19

127

Aerodynamic control, recovery, and sensor design for a first stage flyback booster  

NASA Technical Reports Server (NTRS)

The mission of the flyback group is to control and recover the first stage of a commercially developed winged booster launched from a B-52 at 40,000 ft and Mach 0.8. First-stage separation occurs at 210,000 ft and Mach 8.7; the second and third stages will continue deployment of their 600 lb payload into low Earth orbit. The job of the flyback group begins at this point, employing a modified control system developed to stabilize and maneuver the separated first-stage vehicle to a suitable landing site approximately 130 miles from the launch point over the Pacific Ocean. This multidisciplinary design was accomplished by four subgroups: aerodynamic design/vehicle configuration (ADVC), trajectory optimization, controls, and thermal management.

1989-01-01

128

Liquid Flyback Booster Pre-Phase A Study Assessment. Volume 1  

NASA Technical Reports Server (NTRS)

Mw concept of a flyback booster has been around since early in the Shuttle program. The original two-stage Shuttle concepts used a manned flyback booster. These boosters were eliminated from the program for funding and size reasons. The current Shuttle uses two Redesigned Solid Rocket Motors (RSRMs), which are recovered and refurbished after each flight; this is one of the major cost factors of the program. Replacement options have been studied over the past ten years. The conclusion reached by the most recent study is that the liquid flyback booster (LFBB) is the only competitive option from a life-cycle cost perspective. The purpose of this study was to assess the feasibility and practicality of LFBBs. The study provides an expansion of the recommendations made during the during the aforementioned study. The primary benefits are the potential for enhanced reusability and a reuction of recurring costs. The potential savings in vehicle turnaround could offset the up-front costs. Development of LFBBs requires a commitment to the Shuttle program for 20 to 30 years. LFBBs also offer enhanced safety and abort capabilities. Currently, any failure of an RSRM can be considered catastrophic since them we no intact abort capabilities during the burn of the RSRMS. The performance goal of the LFBBs was to lift a fully loaded Orbiter under optimal conditions, so as not to be the limiting factor of the performance capability of the Shuttle. In addition, a final benefit is the availability of growth paths for applications other than the Shuttle.

Peterson, W.; Ankney, W.; Bell, J.; Berning, M.; Bryant, L.; Bufkin, A.; Cain, L.; Caram, J.; Cockrell, B.; Curry, D.; Diegelman, T.; Gomez, R.; Hong, A.; Jih, D.; Labbe, S.; Le, M.; Leblanc, M.; Lunney, B.; Masciarelli, J.; Musler, J.

1994-01-01

129

Comparison of converter topologies for charging capacitors used in pulsed load applications  

NASA Technical Reports Server (NTRS)

The authors present a qualitative comparison of different power converter topologies which may be utilized for charging capacitors in pulsed power applications requiring voltages greater than 1 kV. The operation of the converters in capacitor charging applications is described, and relevant advantages are presented. All of the converters except one may be classified in the high-frequency switching category. One of the benefits from high-frequency operation is a reduction in size and weight. The other converter discussed is a member of the command resonant changing category. The authors first describe a boost circuit which functions as a command resonant charging circuit and utilizes a single pulse of current to charge the capacitor. The discussion of high-frequency converters begins with the flyback and Ward converters. Then, the series, parallel, and series/parallel resonant converters are examined.

Nelms, R. M.; Schatz, J. E.; Pollard, Barry

1991-01-01

130

Myocardial Bridge  

MedlinePLUS

... surface of the heart. What is a myocardial bridge? A myocardial bridge is a band of heart muscle that lies ... artery, instead of underneath it. With a myocardial bridge, part of a coronary artery dips into and ...

131

Straw Bridges  

NSDL National Science Digital Library

Learners design, build and test a model bridge out of straws. The bridge must span 25 cm across a gap between two tables or two chairs. To measure the load, the bridge must securely hold a small cup. Learners test the load by placing as many pennies in the cup as possible and counting how many the bridge can hold.

Museum Of Science And Industry, Chicago

2012-01-01

132

Four-quadrant flyback converter for direct audio power amplification Petar Ljusev and Michael A.E. Andersen  

E-print Network

) [3] approach for direct conversion of the mains power into acoustic output in one simplified@oersted.dtu.dk Acknowledgments The SICAM project is funded under the grant of the Danish Energy Authority EFP no. 1273 for the switching-mode power conversion. One of them is certainly the audio power amplification, where the switching

133

Popsicle Bridge  

NSDL National Science Digital Library

In this activity, learners explore how engineering has impacted the development of bridges over time, including innovative designs and the challenge of creating bridges that become landmarks for a city. Learners work in teams of "engineers" to design and build their own bridge out of glue and popsicle sticks. Learners test their bridges using weights, evaluate their results, and present their findings to the group.

Ieee

2013-08-30

134

Spaghetti Bridge  

NSDL National Science Digital Library

Civil engineers design structures such as buildings, dams, highways and bridges. Student teams explore the field of engineering by making bridges using spaghetti as their primary building material. Then they test their bridges to see how much weight they can carry before breaking.

K-12 Outreach Office,

135

Compressed Sensing for Resolution Enhancement of Hyperpolarized 13C Flyback 3D-MRSI  

PubMed Central

High polarization of nuclear spins in liquid state through dynamic nuclear polarization has enabled the direct monitoring of 13C metabolites in vivo at very high signal to noise, allowing for rapid assessment of tissue metabolism. The abundant SNR afforded by this hyperpolarization technique makes high resolution 13C 3D-MRSI feasible. However, the number of phase encodes that can be fit into the short acquisition time for hyperpolarized imaging limits spatial coverage and resolution. To take advantage of the high SNR available from hyperpolarization, we have applied compressed sensing to achieve a factor of 2 enhancement in spatial resolution without increasing acquisition time or decreasing coverage. In this paper, the design and testing of compressed sensing suited for a flyback 13C 3D-MRSI sequence are presented. The key to this design was the undersampling of spectral k-space using a novel blipped scheme, thus taking advantage of the considerable sparsity in typical hyperpolarized 13C spectra. Phantom tests validated the accuracy of the compressed sensing approach and initial mouse experiments demonstrated in vivo feasibility. PMID:18367420

Hu, Simon; Lustig, Michael; Chen, Albert P.; Crane, Jason; Kerr, Adam; Kelley, Douglas A.C.; Hurd, Ralph; Kurhanewicz, John; Nelson, Sarah J.; Pauly, John M.; Vigneron, Daniel B.

2008-01-01

136

Efficient Design in a DC to DC Converter Unit  

NASA Technical Reports Server (NTRS)

Space Flight hardware requires high power conversion efficiencies due to limited power availability and weight penalties of cooling systems. The International Space Station (ISS) Electric Power System (EPS) DC-DC Converter Unit (DDCU) power converter is no exception. This paper explores the design methods and tradeoffs that were utilized to accomplish high efficiency in the DDCU. An isolating DC to DC converter was selected for the ISS power system because of requirements for separate primary and secondary grounds and for a well-regulated secondary output voltage derived from a widely varying input voltage. A flyback-current-fed push-pull topology or improved Weinberg circuit was chosen for this converter because of its potential for high efficiency and reliability. To enhance efficiency, a non-dissipative snubber circuit for the very-low-Rds-on Field Effect Transistors (FETs) was utilized, redistributing the energy that could be wasted during the switching cycle of the power FETs. A unique, low-impedance connection system was utilized to improve contact resistance over a bolted connection. For improved consistency in performance and to lower internal wiring inductance and losses a planar bus system is employed. All of these choices contributed to the design of a 6.25 KW regulated dc to dc converter that is 95 percent efficient. The methodology used in the design of this DC to DC Converter Unit may be directly applicable to other systems that require a conservative approach to efficient power conversion and distribution.

Bruemmer, Joel E.; Williams, Fitch R.; Schmitz, Gregory V.

2002-01-01

137

Bookmark Converter  

NSDL National Science Digital Library

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

Broding, Magnus.

138

Straw Bridges  

NSDL National Science Digital Library

Working as engineering teams, students design and create model beam bridges using plastic drinking straws and tape as their construction materials. Their goal is to build the strongest bridge with a truss pattern of their own design, while meeting the design criteria and constraints. They experiment with different geometric shapes and determine how shapes affect the strength of materials. Let the competition begin!

Integrated Teaching And Learning Program

139

Active Bridging  

Microsoft Academic Search

Active networks accelerate network evolution by permitting the network infrastructure to be programmable, on a per-user, per-packet, or other basis. This programmability must be balanced against the safety and security needs inherent in shared resources.This paper describes the design, implementation, and performance of a new type of network element, an Active Bridge. The active bridge can be reprogrammed \\

D. Scott Alexander; Marianne Shaw; Scott M. Nettles; Jonathan M. Smith

1997-01-01

140

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

141

Spaghetti Bridge  

NSDL National Science Digital Library

Play with your food while learning about engineering! Build a spaghetti bridge, then test its strength by piling on the marshmallows, raw spaghetti, raw linguine and coins. Investigate the difference between the strength of bridges made from flat and round building materials (spaghetti is round, while linguine is flat). Learn by doing that circles are among the strongest shapes in nature, and that external and internal stress distributes itself evenly throughout a round structure.

Sciencenter

1999-01-01

142

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

143

Design of power converter for induction furnaces with computer simulations  

Microsoft Academic Search

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

Goce Stefanov; Ljupco Karadzinov; Dejan Karanfilov

2010-01-01

144

Basswood Bridges  

NSDL National Science Digital Library

The Elementary Engineering Design course for freshmen students at Purdue University Calumet consists of two components: one ME and one EE. Due to the two part structure and in order to expose the students to the faculty, it is also team taught. The course counts as two credits, with the format one hour lecture and three hours lab. The basswood bridge is the major project of the ME half and counts for one quarter of the total course grade. The object, as is usual with bridge projects, is to design, build and test a truss bridge having a high strength to weight ratio. The design process includes statics analysis in combination with the tensile and compressive properties of the basswood. The details of the project from initial design to final testing are provided.

Abramowitz, Harvey

2009-09-16

145

Linking Bridges  

NSDL National Science Digital Library

This blog post presents three puzzles which provide an opportunity for learners to use the strategy of trial and error and logical reasoning. The challenge is to connect all of the islands with bridges so that the number on the island corresponds to the number of bridges going to it or from it. This activity also provides the opportunity for students to be puzzle designers by including a blank grid page on which students can design their own versions of the puzzle to share with classmates.

Young, David

2014-01-28

146

Paper Bridge  

NSDL National Science Digital Library

In this engineering activity, challenge learners to construct a paper bridge that can support 100 pennies. Learners discover how they can make a weak material like paper strong enough to support a load pennies by changing the shape of the paper (by rolling, crumpling or folding it).

Boston, Wgbh

2002-01-01

147

Bridges, 2001.  

ERIC Educational Resources Information Center

This document is comprised of the one issue in volume 6 of "Bridges," a publication produced by the California Head Start-State Collaboration Office to detail the activities of the educational partnership and to provide relevant information to programs participating in the partnership. The Summer 2001 issue focuses on providing practitioners with…

Zito, Michael, Ed.

2001-01-01

148

Bridged graphite oxide materials  

NASA Technical Reports Server (NTRS)

Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

2010-01-01

149

Bridge Inspector's Training Manual.  

ERIC Educational Resources Information Center

A guide for the instruction of bridge inspectors is provided in this manual as well as instructions for conducting and reporting on a bridge inspection. The chapters outline the qualifications necessary to become a bridge inspector. The subject areas covered are: The Bridge Inspector, Bridge Structures, Bridge Inspection Reporting System,…

Federal Highway Administration (DOT), Washington, DC. Bureau of Public Roads.

150

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

NASA Technical Reports Server (NTRS)

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

Divan, Deepakraj M.

1990-01-01

151

Building Bridges  

NSDL National Science Digital Library

In this lesson, students build bridges from arithmetical to algebraic thinking by exploring problems that are not limited to single-solution responses. Values organized into tables and graphs are used to move toward symbolic representations. Problem situations at the middle school level involve linear, quadratic, and exponential models. The site is valuable not only for its problems for students but also for the teaching strategy illustrated here.

Day, Roger; Illustrations, Nctm

2000-01-01

152

Bridge Building  

NSDL National Science Digital Library

This is a quick activity (on page 2 of the PDF) about how the arrangement of carbon atoms determines carbon's different properties. Learners will build bridges with Post-It notes that model two types of carbon molecules, graphite and carbon nanotubes, and test which structure of the same material can bear the weight of the most pennies. Also relates to linked video, DragonflyTV Nano: Hockey Sticks.

Twin Cities Public Television, Inc.

2008-01-01

153

Novel Converter Concept for Bearingless Slice Motor Systems  

Microsoft Academic Search

The general trend towards smaller and more economical designs has also reached bearingless slice motor (BSM) systems. Up to now, full-bridge converters have been used in order to independently control the phases of the active magnetic bearing and the drive system. In this paper, a simplified topology based on three half-bridges is proposed to replace two conventional full-bridges. With this,

Martin T. Bartholet; Thomas Nussbaumer; Peter Dirnberger; Johann. W. Kolar

2006-01-01

154

A New Topology of Cascaded Multilevel Converters With Reduced Number of Components for High-Voltage Applications  

Microsoft Academic Search

In this paper, a new topology of a cascaded multilevel converter is proposed. The proposed topology is based on a cas- caded connection of single-phase submultilevel converter units and full-bridge converters. Compared to the conventional multilevel converter, the number of dc voltage sources, switches, installation area, and converter cost is significantly reduced as the number of voltage steps increases. In

Javad Ebrahimi; Ebrahim Babaei; Goverg B. Gharehpetian

2011-01-01

155

Bridge Builders  

NSDL National Science Digital Library

In this interactive game, students build bridges using fractional lengths in the form of fraction bars. Gap length may be known or unknown, entirely empty or partially filled. Fractions to fill the gap must be constructed in specific ways, using the four basic operations. After five tries at one level, the game resets. Note that the game sometimes expects particular answers: students may need to multiply 2/5 by 3 rather than multiplying 3/5 by 2, for example, even though both computations would produce the same result.

2010-01-01

156

A new cascaded multilevel H-bridge drive  

Microsoft Academic Search

In this paper, a general structure for cascaded power converters is presented in which any number of H-bridge cells having any number of voltage levels are series connected to form an inverter phase leg. Equations are introduced for determining an optimal voltage ratio of DC voltages for the H-bridge cells which will maximize the number of voltage levels obtainable resulting

Keith Corzine; Yakov Familiant

2002-01-01

157

Building Big: Bridges  

NSDL National Science Digital Library

This web page describes different aspects of designing bridges. It relates the concept of bridge designing with the real life scenarios. It also includes some bridges around the world and gives some specifications of them.

Foundation, Wgbh E.

2006-07-11

158

Building Big--Bridges  

NSDL National Science Digital Library

This web page describes different aspects of designing bridges. It relates the concept of bridge designing with the real life scenarios. It also includes some bridges around the world and gives some specifications of them.

2008-05-22

159

Build A Bridge  

NSDL National Science Digital Library

This wonderful site, provided by NOVA Online, brings to life the engineering challenges inherent to bridge-building. Designed for those who want the challenge, the site offers four bridging scenarios (with photos): "a 5,000-foot span across an ocean bay where huge ships come and go, ... a 700-foot span across a deep canyon gorge," and two others. A step-by-step tutorial teaches about four different bridge types (arch, beam, suspension, and cable-stayed), after which the user may select a bridge type for each scenario. The site is enhanced by links to other bridge resources, such as the famous bridge-building disaster of the century (Tacoma Narrows Bridge) and the Golden Gate Bridge site, which in turn, links users to other famous bridges including Japan's brand new Akashi Kaikyo Bridge, the longest bridge in the world.

1997-01-01

160

A New Multilevel Converter Topology With Reduced Number of Power Electronic Components  

Microsoft Academic Search

In this paper, a new topology for cascaded multilevel converter based on submultilevel converter units and full-bridge converters is proposed. The proposed topology significantly re- duces the number of dc voltage sources, switches, IGBTs, and power diodes as the number of output voltage levels increases. Also, an algorithm to determine dc voltage sources magnitudes is proposed. To synthesize maximum levels

Javad Ebrahimi; Ebrahim Babaei; Gevorg B. Gharehpetian

2012-01-01

161

Analysis and design of matrix converters for adjustable speed drives and distributed power sources  

E-print Network

. In order to increase the inherent low voltage transfer ratio of the matrix converter, a new three-phase high-frequency link matrix converter is proposed, where a dual bridge matrix converter is modified by adding a high-frequency transformer into dc...

Cha, Han Ju

2004-11-15

162

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

163

Science Shorts: Building Bridges  

NSDL National Science Digital Library

London Bridge is falling down, falling down...Can you finish the song? Although there are various stories that suggest the meaning of this famous nursery rhyme, the London Bridge, which spans the River Thames, did indeed "fall down" several times throughout history. This month's Science Shorts explores what makes bridges stay up. A corresponding activity is included.

Adams, Barbara

2006-07-01

164

Low nasal bridge  

MedlinePLUS

A low nasal bridge is a flattening of the top part of the nose. ... Decreased growth (hypoplasia) of the nasal bridge may due to infections or genetic diseases. A decrease in the height of the nasal bridge is best seen from a side ...

165

Leakage Energy Recovered Narrow Pulsed Voltage Generator Associated with Ultrasound Generator for Liquid Food Sterilization  

Microsoft Academic Search

This paper presents a narrow pulsed voltage generator along with an ultrasound generator for liquid food sterilization. The generator is derived from a bidirectional flyback converter with leakage energy recovery circuits, which can improve efficiency about 12%. In addition, the proposed generator is associated with a half-bridge inverter for generating ultrasound to clean sterilizer electrodes. In this combined generator, the

S.-Y. Tseng; Y.-D. Chang; P.-L. Huang; T.-F. Wu; Y.-M. Chen

2007-01-01

166

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

167

A Current Mode Analysis on Ground Leakage Current Noise Generation in Unbalanced and Balanced Switching Converters  

NASA Astrophysics Data System (ADS)

This paper presents the new switching converter model used for analyzing the generation mechanism of ringing ground leakage (GL) current, generated during the transient, at switch on/off of any switching converter. By applying the Norton model, the proposed new model of switching converter can be formulated. The ringing GL current is evaluated at the switching on/off of the unbalanced (half-bridge converter) and the balanced converter (full-bridge converter) for bidirectional D.C. motor drive used as an example. It is concluded that the measured and simulated results of the generated GL current agree well with the numerical analysis results, analyzed by the proposed new model of switching converter, in terms of the minimum or maximum peak currents and the ringing frequency.

Intachot, Terdsak; Chuladaycha, Nontawat; Prempraneerach, Yothin; Nitta, Shuichi

168

LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED ...  

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

LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED NORTH AND SOUTH PORTIONS OF FACTORY COMPLEX. DANIEL LUTEN DESIGNED THE BRIDGE, AND ILLINOIS BRIDGE COMPANY BUILT IT IN 1918. THE BRIDGE WAS THE SITE OF THE BATTLE OF RUNNING BULLS IN THE 1936-1937 GM SIT DOWN STRIKE. - Delphi Flint West, 300 Chevrolet Avenue, Flint, Genesee County, MI

169

BridgeSPA: Improving Tor Bridges with Single Packet Authorization  

E-print Network

BridgeSPA: Improving Tor Bridges with Single Packet Authorization Rob Smits rdfsmits of the publicly listed relays. To deal with such an adversary, Tor uses bridges, which are unlisted relays's bridge implementation make it easy to dis- cover large numbers of bridges. An adversary that hoards

Hengartner, Urs

170

Semiconductor bridge (SCB) detonator  

DOEpatents

The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge (SCB) igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length. 3 figs.

Bickes, R.W. Jr.; Grubelich, M.C.

1999-01-19

171

Harmonic Modelling of Thyristor Bridges using a Simplified Time Domain Method  

E-print Network

of a 6-pulse thyristor bridge connected to an ac network. Balanced firing of the converter and a balanced interface transformer inductance are assumed. For the special case when the ac network is linear, a closed

Lehn, Peter W.

172

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.

173

LOOKING WEST, BETWEEN READING DEPOT BRIDGE AND SKEW ARCH BRIDGE ...  

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

LOOKING WEST, BETWEEN READING DEPOT BRIDGE AND SKEW ARCH BRIDGE (HAER No. PA-116). - Philadelphia & Reading Railroad, Reading Depot Bridge, North Sixth Street at Woodward Street, Reading, Berks County, PA

174

SULPHITE BRIDGE FROM DOWNSTREAM, BEARING NORTHEAST 25 DEGREES. THE BRIDGE ...  

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

SULPHITE BRIDGE FROM DOWNSTREAM, BEARING NORTHEAST 25 DEGREES. THE BRIDGE ONCE HAD VERTICAL BOARD SIDING BUT VANDALS BURNED IT OFF IN 1981 - Sulphite Railroad Bridge, Former Boston & Maine Railroad (originally Tilton & Franklin Railroad) spanning Winnipesautee River, Franklin, Merrimack County, NH

175

Plans: Poop Deck, Boat Deck, Housetop, Bridge Deck, Upper Bridge ...  

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

Plans: Poop Deck, Boat Deck, Housetop, Bridge Deck, Upper Bridge Deck, Navigating Bridge, Forecastle Deck, Upper Deck, Second Deck and Hold - Saugatuck, James River Reserve Fleet, Newport News, Newport News, VA

176

1. VIEW OF SWING BRIDGE FROM KEDZIE AVENUE BRIDGE, LOOKING ...  

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

1. VIEW OF SWING BRIDGE FROM KEDZIE AVENUE BRIDGE, LOOKING EAST. - Chicago, Madison & Northern Railroad, Sanitary & Ship Canal Bridge, Spanning Sanitary & Ship Canal, east of Kedzie Avenue, Chicago, Cook County, IL

177

Modelling a Suspension Bridge.  

ERIC Educational Resources Information Center

The quadratic function can be modeled in real life by a suspension bridge that supports a uniform weight. This activity uses concrete models and computer generated graphs to discover the mathematical model of the shape of the main cable of a suspension bridge. (MDH)

Rawlins, Phil

1991-01-01

178

Bridge Program Planning Guide  

NSDL National Science Digital Library

This report discusses bridge training programs which are designed to "prepare individuals without the requisite basic skills for postsecondary training leading to career-path employment and further learning in a specific industry or occupational sector." This guide is intended to help those representing community colleges, community organizations, and others plan the development of bridge training programs.

Jenkins, Davis

2012-01-26

179

Dynamic modeling of the Dual-Active Bridge topology for high-power applications  

Microsoft Academic Search

In the present paper the steady-state and the dynamic behavior of the dual-active bridge topology have been studied. The small-signal model of the converter has been derived and theoretical and experimental results are presented. The dual-active bridge is an attractive solution for high- power applications where a bi-directional operation is needed.

Georgios D. Demetriades; Hans-Peter Nee

2008-01-01

180

Overload permit rules applicable to H-type and HS-type bridges  

E-print Network

weight which may be safely carried by a given axle configuration over either a specific bridge or an unknown bridge, the proposed formulae may also yield the "X" rating for any specific truck. Being able to quickly convert any truck to an equivalent HX...

Litchfield, Stephen Charles

2012-06-07

181

Multilevel Cascade H-bridge Inverter DC Voltage Estimation Through Output Voltage Sensing  

E-print Network

Multilevel Cascade H-bridge Inverter DC Voltage Estimation Through Output Voltage Sensing Faete to determine the input voltage value of each cell in a cascade H-bridge multilevel inverter using a sensor multilevel inverter operating under a RLC load. I. INTRODUCTION Multilevel converters make it possible

Tolbert, Leon M.

182

Isolated H-bridge VSC Based 3-phase 4-wire DSTATCOM for power quality improvement  

Microsoft Academic Search

A new topology of DSTATCOM (distribution static compensator) consisting of a H-bridge VSC (voltage source converter) and a star\\/delta transformer is proposed for power quality improvement in a three-phase four-wire distribution system. The star\\/delta transformer provides isolation to the H- bridge VSC as well as mitigates the zero sequence current in a three-phase four-wire distribution system. The H-bridge VSC is

Bhim Singh; P. Jayaprakash; D. P. Kothari

2008-01-01

183

Photocapacitive image converter  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

184

Dead time optimization method for power converter  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

185

An improved soft switching PWM FB DC\\/DC converter for reducing conduction losses  

Microsoft Academic Search

An improved soft switching topology of a full bridge PWM DC\\/DC converter is described. The new topology employs an energy recovery snubber to minimize a circulating current flowing through the transformer and switching devices. By using an energy recovery snubber instead of adding a tapped inductor and a saturable reactor to reduce RMS current stress, the converter achieves nearly zero

Eun-Soo Kim; Kee-Yeon Joe; Moon-Ho Kye; Yoon-Ho Kim; Byung-Do Yoon

1996-01-01

186

Implementation and Control of a Hybrid Multilevel Converter With Floating DC Links for Current Waveform Improvement  

Microsoft Academic Search

Multilevel converters offer advantages in terms of the output waveform quality due to the increased number of levels used in the output voltage modulation. This advantage is particularly true for cascade H-bridge (CHB) converters that can be built to produce a large number of levels owing to their modular structure. Nevertheless, this advantage comes at the cost of multiple dc

César A. Silva; Leopoldo A. Cordova; Pablo Lezana; Lee Empringham

2011-01-01

187

Adaptive dynamic control of a bi-directional DC-DC converter  

Microsoft Academic Search

It is important for a bi-directional dual active bridge DC-DC converter to maintain a stable output voltage under input voltage and output load changes, as well as providing a fast transient step response. However, designing a voltage regulator that achieves this performance is challenging, and requires a precise analytical converter model. This paper develops such a model, firstly by analysing

D. Segaran; B. P. McGrath; D. G. Holmes

2010-01-01

188

A Novel direct AC\\/DC converter for efficient low voltage energy harvesting  

Microsoft Academic Search

In this paper, a direct ac-to-dc power converter is proposed for efficient energy harvesting from the low voltage inertial microgenerators. The conventional power converters use diode bridge rectifiers and condition the microgenerator outputs in two stages. Hence, they are inefficient and may not be a feasible option for very low voltage microgenerators. Moreover, they are not conducive for optimum energy

Suman Dwari; Rohan Dayal; Leila Parsa

2008-01-01

189

Comparison of power converter topologies for permanent magnet small wind turbine system  

Microsoft Academic Search

Permanent magnet based wind generators are one of the more promising technology. This paper presents a comparison of power converter topologies for permanent magnet small wind turbine systems to improve the power quality and to extract the maximum power from wind. Two detailed models are presented and explained: the first configuration is made by a diode-bridge rectifier, a boost converter

N. A. Orlando; M. Liserre; V. G. Monopoli; R. A. Mastromauro; A. Dell'Aquila

2008-01-01

190

To avoid population issue, cable car transports, pedestrian bridge, and  

E-print Network

To avoid population issue, cable car transports, pedestrian bridge, and underground train between membrane and get converted to o2 when ready to be released. Photovoltaic paints applied on wall, solar to the tower, while the others are on the tower such as photovoltaic paint and solar panel on window panes

Farritor, Shane

191

Bay Bridge 360  

NSDL National Science Digital Library

This website was created by the various California transportation agencies that are involved in the enormous job of retrofitting the San Francisco-Oakland Bay Bridge to protect it from being damaged by seismic activity. It is an extremely well thought out website, with an interactive aerial graphic of the Bridge on its homepage that introduces visitors to their work. If you click on the colored circles on the bridge, you can see a slideshow of the construction on that section of the Bridge, and some of the Bridge sections include a time-lapse video of the construction. Additionally, there is a short film visitors can watch to get an overview of the project, by clicking on the blue circle above "Bay Bridge Overview" in the right-hand corner of the homepage. Clicking on the arrow in the left-hand corner of the homepage takes you inside the website where you can find links to "Closures and Detours", "Environmental Issues", for the Final Environmental Impact Statement, detailed explanations of the construction methods under the "Information Center" link, and even "Construction Cams". If you just can't get enough of traffic where you live, just click on "Construction Cams" and see Bay Bridge traffic.

2009-06-08

192

VIEW OF BRIDGE, LOOKING SOUTHWEST, WITH SOUTHERN PACIFIC RAILROAD BRIDGE ...  

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

VIEW OF BRIDGE, LOOKING SOUTHWEST, WITH SOUTHERN PACIFIC RAILROAD BRIDGE IN BACKGROUND. THE PAVEMENT OF THE NORTH APPROACH IS SEEN BURIED ON THE RIGHT. ROADWAY (CENTER) CROSSES THE USUALLY DRY CHANNEL OF THE SALT RIVER. A BALUSTRADE OF THE MILL AVENUE BRIDGE IS SEEN AT THE LOWER LEFT CORNER - Ash Avenue Bridge, Spanning Salt River at Foot of Ash Avenue, Tempe, Maricopa County, AZ

193

M.E. Bridges 1 MELISSA E. BRIDGES  

E-print Network

M.E. Bridges 1 MELISSA E. BRIDGES melbrid@gmail.com Education: Ph.D. Ecology Presentations and Publications): Bridges, M., B.D. Maxwell, and L.J. Rew. 2010. The role of current and historic. 7-11. Denver, CO. [Oral presentation]. Bridges, M., D.L. Shaner, and P. Westra. 2009. The effects

Maxwell, Bruce D.

194

A new ZVS bidirectional DC-DC converter for fuel cell and battery application  

Microsoft Academic Search

This paper presents a new zero-voltage-switching (ZVS) bidirectional dc-dc converter. Compared to the traditional full and half bridge bidirectional dc-dc converters for the similar applications, the new topology has the advantages of simple circuit topology with no total device rating (TDR) penalty, soft-switching implementation without additional devices, high efficiency and simple control. These advantages make the new converter promising for

Fang Z. Peng; Hui Li; Gui-Jia Su; Jack S. Lawler

2004-01-01

195

Multilevel Voltage-Source-Converter Topologies for Industrial Medium-Voltage Drives  

Microsoft Academic Search

This paper presents a technology review of voltage-source-converter topologies for industrial medium-voltage drives. In this highly active area, different converter topologies and circuits have found their application in the market. This paper covers the high-power voltage-source inverter and the most used multilevel-inverter topologies, including the neutral-point-clamped, cascaded H-bridge, and flying-capacitor converters. This paper presents the operating principle of each topology

JosÉ Rodriguez; Steffen Bernet; Bin Wu; Jorge O. Pontt; Samir Kouro

2007-01-01

196

Thermionic photovoltaic energy converter  

NASA Technical Reports Server (NTRS)

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

Chubb, D. L. (inventor)

1985-01-01

197

Gallium phosphide energy converters  

Microsoft Academic Search

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

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

1995-01-01

198

Bridge : an unraveled architecture  

E-print Network

The bridge is an inhabitable structure housing live/work artists studios, galleries and workshops. It is an urban/architectural/personal intervention that strives to explore issues of Iatent/potential narratives within a ...

ElHusseiny, Ahmed

2006-01-01

199

Semiconductor bridge (SCB) igniter  

SciTech Connect

An explosive device is described comprising: a non electrically conducting substrate; an electrical material mounted on the substrate and having a negative temperature coefficient of electrical resistivity at an elevated temperature. The material covers an area of the substrate and defines a pair of spaced pads connected by a bridge; a metallized layer covering each of the spaced pads; an electrical conductor connected to each of the metallized layers, whereby the electrical resistance between the electrical conductors is substantially determined by the electrical resistance of the bridge; and an explosive material covering the device, the area of the bridge in contact with the explosive material being sufficient to ignite the explosive material when the bridge forms a plasma due to electrical current passing therethrough.

Bickes, R.W. Jr.; Schwartz, A.C.

1987-11-24

200

Bridge Rectifier Animation  

NSDL National Science Digital Library

This is an animation of a bridge rectifier circuit or diode bridge. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations. A link provides an optional Quicktime version of this same animation.Other 3-D Circuit Animations can be seen here.

2009-11-26

201

Anatomy and prevalence of atlas vertebrae bridges in a Kenyan population: An osteological study.  

PubMed

Atlas bridges are bony outgrowths over the third segment of the vertebral artery. They may exist as incipient, incomplete, or complete bridges, converting the groove into a deep sulcus, incomplete, or complete foramen respectively. These bridges and their associated foramina display bilateral and sex differences in their prevalence and type. Occurrence of these bridges may predispose to vertebrobasilar insufficiency and Barre-Lieou syndrome. The coexistence of lateral and posterior bridges as well as side predilection is not clear in either sex. Their relative occurrence may also point to some evolutionary patterns. We studied the prevalence, side predilection, coexistence, and anatomical features of atlas bridges using 102 dry atlases (49 males and 53 females) obtained from the osteology department of the National Museums of Kenya. Complete posterior bridges occurred in 14.7% and 13.7% on the right and left sides, respectively. A lateral bridge was found in 3.9% of cases on the right side only. There was positive correlation in the coexistence of the bridges. A retrotransverse foramen was found in 13% of cases. This study has found that posterior and lateral atlas bridges occur in association especially on the right side. Complete bridges were more prevalent in females and were more often present on the right side. This pattern seems to mirror the sexual predilection of vertebral artery compression syndromes. Gender roles may have an influence on the occurrence of these bridges and therefore the syndromes as well. PMID:20533509

Karau, Paul Bundi; Ogengo, Julius A; Hassanali, Jameela; Odula, Paul

2010-09-01

202

DC\\/DC converter for high input voltage: four switches with peak voltage of Vin\\/2, capacitive turn-off snubbing and zero-voltage turn-on  

Microsoft Academic Search

A new four-switch full-bridge DC\\/DC converter topology is especially well-suited for power converters operating from high input voltage: it imposes only half of the input voltage across each of the four switches. The two legs of a full-bridge converter are connected in series with each other, across the DC input source, instead of the usual topology in which each leg

Ivo Barbi; Roger Gules; R. Redl; N. O. Sokal

1998-01-01

203

Performance testing of a high frequency link converter for Space Station power distribution system  

NASA Technical Reports Server (NTRS)

The testing of a brassboard version of a 20-kHz high-frequency ac voltage link prototype converter dynamics for Space Station application is presented. The converter is based on a three-phase six-pulse bridge concept. The testing includes details of the operation of the converter when it is driving an induction machine source/load. By adapting a field orientation controller (FOC) to the converter, four-quadrant operation of the induction machine from the converter has been achieved. Circuit modifications carried out to improve the performance of the converter are described. The performance of two 400-Hz induction machines powered by the converter with simple V/f regulation mode is reported. The testing and performance results for the converter utilizing the FOC, which provides the capability for rapid torque changes, speed reversal, and four-quadrant operation, are reported.

Sul, S. K.; Alan, I.; Lipo, T. A.

1989-01-01

204

A New ZVS Non-Isolated Full-Bridge Voltage Regulator Module with Gate Energy Recovery  

Microsoft Academic Search

In this paper, a novel self-driven zero-voltage-switching (ZVS) non-isolated full bridge (FB) converter is presented for 12 V input VRM application. Existing multiphase buck controller and buck driver can be directly used in the proposed converter. The advantages of the proposed converter are: (1) duty cycle extension; (2) significant switching losses reduction due to ZVS of all the control MOSFETs;

Zhiliang Zhang; Eric Meyer; Yan-Fei Liu; P. C. Sen

2009-01-01

205

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

206

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

207

Thermionic energy converter investigations  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

208

Modular voltage source converter  

US Patent & Trademark Office Database

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

2013-08-06

209

Pennsylvania Covered Bridges  

NSDL National Science Digital Library

Covered bridges cause moments of delight for historic preservationists, and they entered a new place in American popular culture when they figured prominently in a certain Clint Eastwood film in the early 1990s. Recently, staff members and student assistants at Bucknell University spent a significant amount of time creating this digital collection of covered bridge photographs. Interestingly enough, the original photographs were taken by a long-time member of the biology faculty at Bucknell, one Professor Nelson F. Davis. The photos date from 1898 to 1939, and all told, there are over 300 images in this collection. Visitors will enjoy looking over this collection, and these documents will be of great interest to anyone fascinated by these types of bridges, engineering, or the history of rural Pennsylvania.

210

Catalytic Converters and Nanocatalysts  

NSDL National Science Digital Library

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

2014-09-08

211

Muslim Converts in Prison  

Microsoft Academic Search

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

BASIA SPALEK; SALAH EL-HASSAN

2007-01-01

212

3. View northeast showing Kenyon Arch Bridge (Rhode Island Bridge ...  

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

3. View northeast showing Kenyon Arch Bridge (Rhode Island Bridge No. 148) over Pawcatuck River (foreground) and portion of Kenyon Industries mill complex (background). - Kenyon Village, Kenyon School Road, Sherman Avenue, & Lewiston Avenue, Richmond (historical), Providence County, RI

213

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

214

SBIR Phase II Bridge Award  

Cancer.gov

National Cancer Institute Bridging the Funding Gap for Promising Cancer Therapeutics, Imaging Technologies, Interventional Devices, Diagnostics, and Prognostics SBIR Phase II Bridge Award The National Cancer Institute (NCI) Small Business Innovation

215

Application of a Modular Multilevel Cascade Converter (MMCC-SDBC) to a STATCOM  

NASA Astrophysics Data System (ADS)

This paper presents the application of a modular multilevel cascade converter based on single-delta bridge-cells (MMCC-SDBC) to a STATic synchronous COMpensator (STATCOM), particularly for negative-sequence reactive-power control. The SDBC is characterized by cascade connection of multiple single-phase H-bridge (or full-bridge) converter cells per leg, which facilitates flexible circuit design, low voltage steps, and low electro-magnetic interference (EMI) emissions. However, there is no published report on such a STATCOM with experimental verification or a control strategy. This paper designs, constructs, and tests a 100-V 5-kVA PWM STATCOM based on the SDBC with focus on the operating principle and performance. Experimental results confirm that this converter can control not only the positive-sequence reactive power but also the negative-sequence reactive power and low-frequency active power intended for the flicker compensation of arc furnaces.

Hagiwara, Makoto; Maeda, Ryo; Akagi, Hirofumi

216

The Bridge to Somewhere  

ERIC Educational Resources Information Center

Since its inception in 2000, Pan-Asian American Community House's (PAACH's) education mission has bridged Asian-American studies to student life. PAACH initiatives have helped spread Asian-American diaspora to thousands of students at the University of Pennsylvania. They have also helped students determine for themselves what it means to be a…

Lum, Lydia

2009-01-01

217

Building Migratory Bridges  

ERIC Educational Resources Information Center

The Building Migratory Bridges (BOMB) program--a collaboration between the Marvel wood School and Audubon Sharon in Connecticut and Conservation Research Education Action (CR EA), a U.S. not-for-profit in Panama--uses nontropical migratory bird research in the United States and Panama to demonstrate how negative environmental impacts in one…

Roy, Michael; Doss, Laurie K.

2007-01-01

218

URI Student Bridge  

Microsoft Academic Search

The project that came to be known as URI Student Bridge began with my amazing college experience and my desire to share that experience with others who were making the decision of whether to begin a college experience of their own. I have been very fortunate to have the funding and motivation to attend college, and have had many opportunities

Nicole Aragi

2008-01-01

219

Bridging Disciplinary Boundaries  

ERIC Educational Resources Information Center

Interdisciplinary education promotes the unity of knowledge by bridging the cultural divide between the social constructs of disciplines and encourages the development of knowledge to enhance society. As an inquiry-based and relevant approach that expands and advances knowledge, interdisciplinary education facilitates creativity and flexibility,…

Mei, Linda

2009-01-01

220

Bridges link the world.  

PubMed

Organizations that use videoconferencing quickly discover how a video call connecting two sites can be a productive and cost effective way to hold meetings, offer remote diagnosis and participate in distance learning. But, administrative and education applications, in particular, are likely to require that multiple sites be networked at the same time. A simple solution is video bridging. PMID:10173298

Kaiser, F

1997-01-01

221

Semiconductor bridge (SCB) igniter  

Microsoft Academic Search

An explosive device is described comprising: a non electrically conducting substrate; an electrical material mounted on the substrate and having a negative temperature coefficient of electrical resistivity at an elevated temperature. The material covers an area of the substrate and defines a pair of spaced pads connected by a bridge; a metallized layer covering each of the spaced pads; an

R. W. Jr. Bickes; A. C. Schwartz

1987-01-01

222

Quantum bidding in Bridge  

E-print Network

Quantum methods allow to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this fact are thus far limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain advantage in famous, immensely popular, card game - Bridge. The essence of a winning strategy in Bridge is efficient communication between the partners. The rules of the game allow only specific form of communication, of a very low complexity (effectively one has a strong limitations on number of exchanged bits). Surprisingly, our quantum technique is not violating the existing rules of the game (as there is no increase in information flow). We show that our quantum Bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt (CHSH) game, which is equivalent to a $2\\to 1$ quantum random access code. Thus our experiment is also a realization of such protocols. However, this correspondence is not full which enables the Bridge players to have efficient strategies regardless of the quality of their detectors.

S. Muhammad; A. Tavakoli; M. Kurant; M. Pawlowski; M. Zukowski; M. Bourennane

2014-03-17

223

Bridging the Gap?  

ERIC Educational Resources Information Center

The political context of the conversion of the Historic Tramway Bridge, adjacent to Sandon Point in Bulli (NSW, Australia), and how this was exploited to serve predetermined ends, illustrates that technologies can be designed to have particular social (and political) effects. Through reflection on this relatively small engineering project, this…

Salter, Colin

2009-01-01

224

CMOS Bridging Fault Detection  

Microsoft Academic Search

The authors compare the performance of two test generation techniques, stuck fault testing and current testing, when applied to CMOS bridging faults. Accurate simulation of such faults mandated the development of several new design automation tools, including an analog-digital fault simulator. The results of this simulation are analyzed. It is shown that stuck fault test generation, while inherently incapable of

Thomas M. Storey; Wojciech Maly

1990-01-01

225

BUILDING BRIDGES IN HEALTHCARE  

Microsoft Academic Search

or those who have not been in the Charleston area for several years, 2005 has marked the opening of a fabulous new span that links Charleston with Mount Pleasant. In mid July, the entire region turned out to stroll over the new bridges and celebrate their completion with a monumental fireworks display. The two dilapidated structures that had offered an

Bill Hueston

226

A Guide to Covered Bridges  

NSDL National Science Digital Library

A Guide to Covered Bridges, offered by Drexel University, Philadelphia, Pennsylvania, transforms the Web into a time machine. Find the answer to the question, why are there so many covered bridges, and why in Pennsylvania and the Northeast? The Drexel University Honors Program sponsors this guide to dozens of covered bridges of the Philadelphia region. Driving tours are suggested, and bridge images are indexed by season (fall color, winter, snow and ice, spring/summer) and structure as well as county.

227

A 10 kW dc-dc converter using IGBTs with active snubbers. [Insulated Gate Bipolar Transistor  

NASA Technical Reports Server (NTRS)

This full bridge dc-dc converter employs zero voltage switching (ZVS) on one leg and zero current switching (ZCS) on the other. This technique produces exceptionally low IGBT switching losses through the use of an active snubber that recycles energy back to the source. Experimental results are presented for a 10 kW, 20 kHz converter.

Masserant, Brian J.; Shriver, Jeffrey L.; Stuart, Thomas A.

1993-01-01

228

77 FR 16784 - General Bridge Regulation; Amendment  

Federal Register 2010, 2011, 2012, 2013

...USCG-2008-1188] RIN 1625-AB36 General Bridge Regulation; Amendment AGENCY: Coast...rulemaking concerning amendments to the general bridge regulations. The rulemaking was initiated...clarify the statutory responsibilities of bridge owners to remove their bridges from...

2012-03-22

229

A ZVZCS PWM FB DC\\/DC converter using a modified energy-recovery snubber  

Microsoft Academic Search

The conventional high-frequency phase-shifted zero-voltage-switching (ZVS) full-bridge DC\\/DC converter has a disadvantage, in that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of the transformer and switching devices are increased. To alleviate this problem, this paper proposes an improved zero-voltage zero-current switching (ZVZCS) phase-shifted full-bridge

Eun-Soo Kim; Yoon-Ho Kim

2002-01-01

230

Maintaining Minnesota's Unique Bridge Inventory  

E-print Network

Bridge revealed condition issues with the wire rope suspenders · A similar inspection of the Bong Bridge;Install New Suspender #12;Replace ­ New Hanger #12;Testing ­ Visual Inspection Areas of corrosion;Blatnik and Bong Bridges Wire Rope Replacement · In 2007, a fracture critical inspection of the Blatnik

Minnesota, University of

231

System reliability of suspension bridges  

Microsoft Academic Search

Provisions for the design of existing suspension bridges often rely on a deterministic basis. Consequently, the reliability of these bridges cannot be assessed if current provisions are applied. In order to develop cost-effective design and maintenance strategies for suspension bridges a system reliability-based approach has to be used. This is accomplished by a probabilistic finite element geometrically nonlinear analysis approach.

Kiyohiro Imai; Dan M. Frangopol

2002-01-01

232

Gaussian bridges Dario Gasbarra1  

E-print Network

Gaussian bridges Dario Gasbarra1 , Tommi Sottinen2 , and Esko Valkeila3 1 Department of Mathematics.valkeila@hut.fi Summary. We consider Gaussian bridges; in particular their dynamic representa- tions. We prove a Girsanov theorem between the law of Gaussian bridge and the original Gaussian process, which holds with natural

Sottinen, Tommi

233

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

234

Power electronic converter technology  

Microsoft Academic Search

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

ROBERT L. STEIGERWALD

2001-01-01

235

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

236

Purplemath: Cancelling / Converting Units  

NSDL National Science Digital Library

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

Stapel, Elizabeth

237

Digital to synchro converter  

NASA Technical Reports Server (NTRS)

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

Predina, Joseph P. (Inventor)

1989-01-01

238

Multilevel converters -- A new breed of power converters  

SciTech Connect

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

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

1996-05-01

239

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

240

Vehicle Impact in Box Girder Bridges and Bridge Substructures. Phase 1. Straight Box Girder Bridges.  

National Technical Information Service (NTIS)

This is the first part of the three-year project on vehicle impact in box girder bridges and bridge substructures. The objective of this investigation is to present a procedure for the study of the dynamic response of straight box girder bridges and to an...

D. Huang, T. L. Wang

1994-01-01

241

A three-phase soft-switched high power density DC\\/DC converter for high power applications  

Microsoft Academic Search

The authors present three DC\\/DC converter topologies suitable for high-power-density high-power applications. All three circuits operate in a soft-switched manner, making possible a reduction in device switching losses and an increase in switching frequency. The three-phase dual-bridge converter proposed is seen to have the most favorable characteristics. This converter consists of two three-phase inverter stages operating in a high frequency

R. W. De Doncker; D. M. Divan; M. H. Kheraluwala

1988-01-01

242

A three-phase soft-switched high-power-density DC\\/DC converter for high-power applications  

Microsoft Academic Search

Three DC\\/DC converter topologies suitable for high-power-density high-power applications are presented. All three circuits operate in a soft-switched manner, making possible a reduction in device switching losses and an increase in switching frequency. The three-phase dual-bridge converter proposed is shown to have the most favorable characteristics. This converter consists of two three-phase inverter stages operating in a high-frequency six-step mode.

Rik W. A. A. De Doncker; Deepakraj M. Divan; Mustansir H. Kheraluwala

1991-01-01

243

Molecular engineering with bridged polysilsesquioxanes  

SciTech Connect

Bridged polysilsesquioxanes are a class of hybrid organic-inorganic materials that permit molecular engineering of bulk properties including porosity. Prepared by sol-gel polymerization of monomers with two or more trialkoxysilyl groups, the materials are highly cross-linked amorphous polymers that are readily obtained as gels. The bridging configuration of the hydrocarbon group insures that network polymers are readily formed and that the organic functionality is homogeneously distributed throughout the polymeric scaffolding at the molecular level. This permits the bulk properties, including surface area, pore size, and dielectric constant to be engineered through the selection of the bridging organic group. Numerous bridging groups have been incorporated. This presentation will focus on the effects that the length, flexibility, and substitution geometry of the hydrocarbon bridging groups have on the properties of the resulting bridged polysilsesquioxanes. Details of the preparation, characterization, and some structure property relationships of these bridged polysilsesquioxanes will be given.

LOY,DOUGLAS A.; SHEA,KENNETH J.

2000-05-09

244

Cost of Impressed Current Cathodic Protection for Coastal Oregon Bridges  

Microsoft Academic Search

The State of Oregon is using arc-sprayed zinc coatings for anodes in impressed current cathodic protection (ICCP) systems on reinforced concrete coastal bridges. The two lowest bids for four ICCP projects were averaged and converted to 1997 dollars. The total average cost for the ICCP projects was $51.63\\/ft2 ($555.51\\/m2) of protected concrete. The cathodic protection part of the ICCP projects

Gordon R. Holcomb; Curtis B. Cryer

1998-01-01

245

Asymmetric Switching For A PWM H-Bridge Power Circuit  

NASA Technical Reports Server (NTRS)

Only two of four switches interrupt substantial current. An asymmetric timing scheme improves design and operation of pulse-width-modulation (PWM) H-bridge switch-and-transformer circuit. Circuit part of dc-to-dc converter or dc-to-ac inverter; in either case, output current or voltage regulated by adjusting times of opening and closing of semiconductor switches 1 through 4 to adjust durations of current pulses in primary winding of transformer.

Wong, See-Pok

1995-01-01

246

Electrical Actuation Technology Bridging  

NASA Astrophysics Data System (ADS)

This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.

Hammond, Monica; Sharkey, John

1993-05-01

247

Bridge-NOAA Collection  

NSDL National Science Digital Library

The Bridge-NOAA Collection is a selection of exemplary resources from the National Oceanic and Atmospheric Administration (NOAA) that have been reviewed by educators and found to be well-suited for educational purposes. The collection also emphasizes professional-development opportunities for teachers. There is a strong focus on research data and its use in teaching. The collection provides educators with accurate and useful information on global, national, and regional ocean-science topics.

2007-10-19

248

Bridging the Gap  

NSDL National Science Digital Library

A newly appointed joint hire in the College of Arts and Sciences, Department of Natural Sciences and the College of Education, Department of Middle/Secondary Education, was charged with the responsibility of bridging the communication gap between these two departments and colleges. To meet this challenge, four collaborative projects were developed between the Natural Sciences faculty and Middle/Secondary Education science students that will become formally established in future university courses.

Eason, Grace

2004-11-01

249

Build a Bridge  

NSDL National Science Digital Library

In this activity, learners use recycled materials to build a bridge that holds as many potatoes as possible. They investigate weight, height, strength, and measurement as they seek design solutions. The activity instructions include ways to adjust the level of challenge for learners of different ages. Try this at family events or to engage all ages. Available as a web page and a downloadable PDF. Students should have the ability to use tape and scissors.

2010-01-01

250

BATS IN AMERICAN BRIDGES  

Microsoft Academic Search

Bridges and culverts were evaluated as bat roosting habitat in 25 U.S. states at elevations from sea level to 10,000 feet. Field surveys were conducted at 2,421 highway structures. Scientific literature was reviewed, and local biologists and engineers were interviewed, leading to the discovery of approximately 4,250,000 bats of 24 species living in 211 highway structures. Only one percent of

Brian W. Keeley; Merlin D. Tuttle

251

BRIDGE Other Resources  

NSDL National Science Digital Library

Bridge Ocean Resources provide access to ocean sciences educational materials with particular emphasis on K-12 audiences. The collection emphasizes biological oceanography, aquaria, research institutions, career information, student opportunities and announcements. There is a strong focus on research data and its use in teaching. The collection provides educators with a source of accurate and useful information on global, national, and regional ocean science topics, and gives researchers a contact point for educational outreach.

252

Low pressure solar thermal converter  

Microsoft Academic Search

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

Gerald Muller

253

164 Currencies Converter  

NSDL National Science Digital Library

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

1997-01-01

254

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

255

Cycloidal Wave Energy Converter  

SciTech Connect

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

Stefan G. Siegel, Ph.D.

2012-11-30

256

An improved soft-switching PWM FB DC\\/DC converter for reducing conduction losses  

Microsoft Academic Search

An improved soft-switching topology of a full-bridge (FB) pulsewidth-modulated (PWM) DC\\/DC converter is described. The new topology employs an energy-recovery snubber to minimize a circulating current flowing through the transformer and switching devices. By using an energy-recovery snubber instead of adding a tapped inductor and a saturable reactor to reduce RMS current stress, the converter achieves zero-current switching (ZCS) for

Eun-Soo Kim; Kee-Yeon Joe; Moon-Ho Kye; Yoon-Ho Kim; Byung-Do Yoon

1999-01-01

257

A Voltage-Controlled PFC Cuk Converter-Based PMBLDCM Drive for Air-Conditioners  

Microsoft Academic Search

This paper deals with a Cuk dc–dc converter as a single-stage power-factor-correction converter for a permanent-magnet (PM) brushless dc motor (PMBLDCM) fed through a diode bridge rectifier from a single-phase ac mains. A three-phase voltage-source inverter is used as an electronic commutator to operate the PMBLDCM driving an air-conditioner compressor. The speed of the compressor is controlled to achieve optimum

Sanjeev Singh; Bhim Singh

2012-01-01

258

A Voltage Controlled PFC Cuk Converter Based PMBLDCM Drive for Air-Conditioners  

Microsoft Academic Search

This paper deals with a Cuk DC-DC converter as a single-stage power factor correction (PFC) converter for a permanent magnet brushless DC motor (PMBLDCM) fed through a diode bridge rectifier (DBR) from a single-phase AC mains. A three-phase voltage source inverter is used as an electronic commutator to operate the PMBLDCM driving an air conditioner compressor. The speed of the

Sanjeev Singh; Bhim Singh

2010-01-01

259

The three-level ZVS-PWM DC-to-DC converter  

Microsoft Academic Search

A novel high-frequency DC-to-DC power converter for high voltage and high power is introduced which features zero voltage switching (ZVS), operation at constant frequency, regulation by pulse width modulation (PWM), and low RMS current stress upon power switches. Its greatest attribute, in comparison with the full-bridge (FB-ZVS-PWM) converter, is that the voltage across the switches is half of the input

J. R. Pinheiro; I. Barbi

1993-01-01

260

Sinusoidal line current rectification at unity power factor with boost quasi-resonant converters  

Microsoft Academic Search

A sinusoidal line current rectifier is considered at unity power factor, where the conventional boost converter, usually utilized between the diode rectifier bridge and the DC bus capacitor, is replaced with a boost zero-current switching quasi-resonant converter (boost ZCS-QRC). The zero-current switching quasi-resonant rectifier (ZCS-QRR) is analyzed theoretically. Normalized curves are plotted, and equations that allow high flexibility in design

Ivo Barbi; S. A. Oliveira da Silva

1990-01-01

261

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

262

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

263

Gallium phosphide energy converters  

SciTech Connect

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

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

1995-10-01

264

Gallium phosphide energy converters  

NASA Astrophysics Data System (ADS)

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

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

1995-10-01

265

Tacoma Narrows Bridge: Extreme History  

NSDL National Science Digital Library

Stretching across the southern portion of Puget Sound, the elegant Tacoma Narrows bridge is considered one of the finest suspension bridges in the United States. The current bridge is the second on the site, as it was constructed in 1950 to serve as a replacement to the famous "Galloping Gertie" bridge, which collapsed in a windstorm in the fall of 1940. Currently, the Washington State Department of Transportation is building a bridge to replace the existing structure, and it is anticipated that it will be completed in 2007. This site offers a host of materials on all three structures, including ample information on the construction of the bridges and their aesthetic appeal. Along with these materials, the site also provides a glossary of related terms, Weird Facts, and some information about the dog "Tubby", who perished when "Galloping Gertie" collapsed on that fateful fall day back in 1940.

266

Resistive anode image converter  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

267

Electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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

Bailey, R. L. (inventor)

1973-01-01

268

Virtual Bridge Design  

NSDL National Science Digital Library

The West Point Bridge Design (WPBD) building project engages students in project-based learning by giving them a real-life problem to solve. By using technology, students are able to become involved in solving problems that they normally would not encounter. Involvement with interactive websites, such as WPBD, assists students in using higher-level thinking skills and problem solving (NSTA 2006). It is important that we keep our students engaged in learning science, as the scientific society of tomorrow depends upon the science students of today.

Jeanpierre, Bobby; Bisogno, Janet

2008-09-01

269

West Point Bridge Design Contest  

NSDL National Science Digital Library

The second annual West Point Bridge Design Contest concluded in May 2003. Although it is uncertain whether the contest will receive funding for future competitions, its Web site has a number of educational resources for middle and high school students. The main feature is the bridge design software, which allows the user to "model, test, and optimize a steel highway bridge, based on realistic specifications, constraints, and performance criteria." Completed designs can be submitted online for unofficial judging. The book, Designing and Building File-Folder Bridges, can also be freely downloaded. This site is also reviewed in the July 4, 2003 NSDL MET Report.

2003-01-01

270

West Point Bridge Design Contest  

NSDL National Science Digital Library

The West Point Bridge Design Contest Web site has a number of educational resources for middle and high school students. The main feature is the bridge design software, which allows the user to "model, test, and optimize a steel highway bridge, based on realistic specifications, constraints, and performance criteria." Completed designs can be submitted online for unofficial judging. The book, Designing and Building File-Folder Bridges, can also be freely downloaded. This site is also reviewed in the July 4, 2003 NSDL MET Report.

2007-03-27

271

47 CFR 80.331 - Bridge-to-bridge communication procedure.  

Code of Federal Regulations, 2012 CFR

...Telecommunication 5 2012-10-01 2012-10-01 false Bridge-to-bridge communication procedure. 80.331 Section 80...Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a)...

2012-10-01

272

47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.  

Code of Federal Regulations, 2011 CFR

...Telecommunication 5 2011-10-01 2011-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section...SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1007...

2011-10-01

273

47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.  

Code of Federal Regulations, 2013 CFR

...Telecommunication 5 2013-10-01 2013-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section...SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1007...

2013-10-01

274

47 CFR 80.331 - Bridge-to-bridge communication procedure.  

Code of Federal Regulations, 2013 CFR

...Telecommunication 5 2013-10-01 2013-10-01 false Bridge-to-bridge communication procedure. 80.331 Section 80...Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a)...

2013-10-01

275

47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.  

Code of Federal Regulations, 2012 CFR

...Telecommunication 5 2012-10-01 2012-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section...SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1007...

2012-10-01

276

47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.  

Code of Federal Regulations, 2010 CFR

...Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section...SERVICES Radiotelephone Installations Required by the Bridge-to-Bridge Act § 80.1007...

2010-10-01

277

47 CFR 80.331 - Bridge-to-bridge communication procedure.  

Code of Federal Regulations, 2010 CFR

...Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge communication procedure. 80.331 Section 80...Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a)...

2010-10-01

278

47 CFR 80.331 - Bridge-to-bridge communication procedure.  

Code of Federal Regulations, 2011 CFR

...Telecommunication 5 2011-10-01 2011-10-01 false Bridge-to-bridge communication procedure. 80.331 Section 80...Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a)...

2011-10-01

279

Extended bridge algorithms for large networks  

Microsoft Academic Search

A network bridge is a device that operates at the ISO data link level and routes packets across extended networks, commonly composed of multiple local area networks (LANs) and bridges. A set of algorithms that greatly extends the application of the network bridge is presented. This multitree bridge algorithm allows networks of arbitrary topology and capacity to use bridge routing.

W. D. Sincoskie; C. J. Cotton

1988-01-01

280

Accurate Small-Signal Model for the Digital Control of an Automotive Bidirectional Dual Active Bridge  

Microsoft Academic Search

The derivation of an accurate small-signal model for a galvanically isolated, bidirectional dc-dc converter and the implementation of a corresponding controller on a DSP as well as key methods and functions required for the digital implementation are detailed in this paper. The investigated dc-dc converter, an automotive dual active bridge (DAB) system, enables power transfer between a low-voltage port (ranging

Florian Krismer; Johann W. Kolar

2009-01-01

281

Efficient Power Converters for PV Arrays : Scalable Submodule Power Conversion for Utility-Scale Photovoltaics  

SciTech Connect

Solar ADEPT Project: SolarBridge is developing a new power conversion technique to improve the energy output of PV power plants. This new technique is specifically aimed at large plants where many solar panels are connected together. SolarBridge is correcting for the inefficiencies that occur when two solar panels that encounter different amounts of sun are connected together. In most conventional PV system, the weakest panel limits the energy production of the entire system. That’s because all of the energy collected by the PV system feeds into a single collection point where a central inverter then converts it into useable energy for the grid. SolarBridge has found a more efficient and cost-effective way to convert solar energy, correcting these power differences before they reach the grid.

None

2012-02-23

282

Pulsed thermionic converter study  

NASA Technical Reports Server (NTRS)

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

1976-01-01

283

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.

284

WILLIAM B. BRIDGES INTERVIEWED BY  

E-print Network

WILLIAM B. BRIDGES (1934 ­ ) INTERVIEWED BY SHIRLEY K. COHEN May ­ June 2001, March 2004 Photo, and an Addendum, March 2004, with William B. Bridges, Carl F. Braun Professor of Engineering in the Division, and GTE. Concludes the interview with his recollections of Caltech President Marvin L. (Murph) Goldberger

Low, Steven H.

285

Mathematical models of suspension bridges  

Microsoft Academic Search

In this work we try to explain various mathematical models describing the dynamical behaviour of suspension bridges such as the Tacoma Narrows bridge. Our attention is concentrated on the derivation of these models, an interpretation of particular parameters and on a discussion of their advantages and disadvantages. Our work should be a starting point for a qualitative study of dynamical

Gabriela Taj?ová

1997-01-01

286

Mathematics in Use: Suspension Bridges.  

ERIC Educational Resources Information Center

Reviews the mathematics utilized in the design and construction of suspension bridges, in general, then illustrates these mathematical concepts by examining data associated with the Mackinac Bridge, which connects the two peninsulas of Michigan. Emphasizes the strong interest factor these gigantic structures have for students by attaching a sense…

Ginther, John L.

1992-01-01

287

Toni Rttimann Bridges for people  

E-print Network

Toni Rüttimann Bridges for people 1 March 2013 Politecnico di Milano - Campus Bovisa­ aula BL2701 personal effects, the second one for his suspension bridgebuilding. Toni helps the more destitute people to build or re-build their own bridges, often after a hurricane, an earthquake, a war event. The story

288

Causes of Bridge Pier Staining.  

National Technical Information Service (NTIS)

Four types of bridge stains exist in Arkansas: Rust stains - those stains directly traceable to rust; red stains - broad stains which are not directly traceable to rust; gray stains - similar to red stains except for color; and graffiti. Bridge stains in ...

S. I. Thornton, C. Springer

1974-01-01

289

Halliburton Composite Bridge Plug Assembly  

Microsoft Academic Search

The overall objectives of this CRADA were to assist Halliburton in analyzing a composite bridge plug and to determine why their original design was failing in the field. In Phase 1, finite element analyses were done on the original composite slip design and several alternative designs. The composite slip was the component in the bridge plug that was failing. The

J. M. Starbuck; C. R. Luttrell; G. Aramayo

2005-01-01

290

Trigenomic Bridges for Brassica Improvement  

Microsoft Academic Search

We introduce and review Brassica crop improvement via trigenomic bridges. Six economically important Brassica species share three major genomes (A, B, and C), which are arranged in diploid (AA, BB, and CC) and allotetraploid (AABB, AACC, and BBCC) species in the classical triangle of U. Trigenomic bridges are Brassica interspecific hybrid plants that contain the three genomes in various combinations,

Sheng Chen; Matthew N. Nelson; Anne-Marie Chèvre; Eric Jenczewski; Zaiyun Li; Annaliese S. Mason; Jinling Meng; Julie A. Plummer; Aneeta Pradhan; Kadambot H. M. Siddique; Rod J. Snowdon; Guijun Yan; Weijun Zhou; Wallace A. Cowling

2011-01-01

291

75 FR 41281 - Bridge Safety Standards  

Federal Register 2010, 2011, 2012, 2013

...sudden damage from severe weather conditions or heavy water...all available design and modification documents and current reports...other purposes. Bridge modification and bridge repair. ``Bridge modification'' means a change to...

2010-07-15

292

33 CFR 115.40 - Bridge repairs.  

Code of Federal Regulations, 2012 CFR

...Waters 1 2012-07-01 2012-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...

2012-07-01

293

33 CFR 115.40 - Bridge repairs.  

Code of Federal Regulations, 2010 CFR

...Waters 1 2010-07-01 2010-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...

2010-07-01

294

49 CFR 236.713 - Bridge, movable.  

Code of Federal Regulations, 2010 CFR

...Transportation 4 2010-10-01 2010-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation...SYSTEMS, DEVICES, AND APPLIANCES Definitions § 236.713 Bridge, movable. That section of a structure bridging a...

2010-10-01

295

33 CFR 115.40 - Bridge repairs.  

Code of Federal Regulations, 2013 CFR

...Waters 1 2013-07-01 2013-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...

2013-07-01

296

33 CFR 115.40 - Bridge repairs.  

Code of Federal Regulations, 2011 CFR

...Waters 1 2011-07-01 2011-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE...

2011-07-01

297

Bridge Building: Art and Science  

NSDL National Science Digital Library

This site is one of the most substantial, comprehensive sources on the Internet dedicated to bridge design and history. It has an incredible list of sections from which to choose, and each describes a particular bridge type or characteristic. Several pictures are included from all over the world that give examples of arch, truss, suspension, and many other bridge designs. There are also explanations of forces that act upon bridges, as well as what issues are considered when choosing the kind of bridge to build over a span. Perhaps the only drawback to the site is that there is so much information; the main page seems a bit cluttered. However, it does not really hamper navigating the site.

298

Burning trees and bridges  

NASA Technical Reports Server (NTRS)

Most burning of biomass is the result of human activity, and on a global scale it is increasing. Tropospheric concentrations of CO2, CO, CH4, non-methane hydrocarbons, and ozone are all increasing with time; global biomass burning may make an important contribution to this increase and thus to potential global climate change. The nitrogen cycle also can have important climatic effects. Nitrous oxide put into the atmosphere by biomass burning is a greenhouse gas 250 times more powerful (molecule for molecule) than carbon dioxide. Nitric oxide, as well as being a photochemical precursor of ozone, a major pollutant in the troposphere, produces nitric acid, the fastest-growing component of acid rain. Hence, the new bridge in the nitrogen cycle is of more than mere technical interest.

Levine, Joel S.

1990-01-01

299

Stanford: The Bridge Project  

NSDL National Science Digital Library

Stanford University's Bridge Project: Strengthening K-16 Transition Policies emphasizes that "reforms affecting K-12 and higher education must occur across systems in order to achieve the desired outcomes." Their approach is to improve opportunities for all students to enter and succeed in higher education by strengthening the alignment between higher education admissions-related requirements and K-12 curriculum frameworks, standards, and assessments. They conduct research that is meant to inform educational institutions and federal, state, and local agencies through descriptive analysis of the policies, identification of "disjunctures that exist in the current policy environment," and recommendations for improving the current system. Details about this program as well as their policy reports and briefs are available from their website.

300

The Bridges Organization  

NSDL National Science Digital Library

The connection between art and mathematics is well known, and the Bridges Organization has been bringing together these two worlds since 1998. The group started in Kansas, and since then they have traveled to cities in North America and Europe. On this site, visitors can learn about their past conferences, and view some of their galleries of images. The "Virtual Museum" area is a real treat, and visitors can look at spherical paintings, geometric sculptures, and algorithmic visual art. Moving on, the "Educational Resource Center" area features links of interest to educators, including sites dedicated to teaching mathematical thinking through origami and such. The site is rounded out by past conference reports and information about their leadership.

301

Bridges to Structure  

NSDL National Science Digital Library

This project's goals are to investigate structural components at a variety of levels: molecularly, cellularlly (histologically),phylogenetically, organismally, etc. Traditionally the stuctural classes at many institutions have used primarily dissection and histology for comparison of different vertebrate classes. In this project, we began to develop exercises at the molecular level using gemonmic and proteomic information to form phylogenetic trees, started a chart of materials available at NCBI for use in comparison (phylogentically and visually) of characteristic proteins from specific organ systems, and initiated thinking about a project to start a pictorial archive of dissection activities and histological meassurements. With the signifcant movement to integrate more material within biology and other areas of science and mathematics, building bridges (exercises) amongst a number of levels seems relevant. In addition, adding more open-ended projects with greater manipulation of data and mathematical manipulation in these courses is very desirable.

Peter Woodruff (Champlain-St. Lambert College;); Joyce Cadawallader (Saint-Mary-of-the-Woods College;)

2004-06-12

302

Semiconductor Bridge Cable Test  

SciTech Connect

The semiconductor bridge (SCB) is an electroexplosive device used to initiate detonators. A C cable is commonly used to connect the SCB to a firing set. A series of tests were performed to identify smaller, lighter cables for firing single and multiple SCBs. This report provides a description of these tests and their results. It was demonstrated that lower threshold voltages and faster firing times can be achieved by increasing the wire size, which reduces ohmic losses. The RF 100 appears to be a reasonable substitute for C cable when firing single SCBs. This would reduce the cable volume by 68% and the weight by 67% while increasing the threshold voltage by only 22%. In general, RG 58 outperforms twisted pair when firing multiple SCBs in parallel. The RG 58's superior performance is attributed to its larger conductor size.

KING, TONY L.

2002-01-01

303

Proposed electromagnetic wave energy converter  

NASA Technical Reports Server (NTRS)

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

Bailey, R. L.

1973-01-01

304

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

305

Chesapeake Bay Bridge-Tunnel  

NSDL National Science Digital Library

The Chesapeake Bay Bridge-Tunnel is a 20 mile long series of bridges and tunnels that connect Virginia Beach/Norfolk to Virginia's Eastern Shore. The project is an engineering marvel; besides supporting vehicular traffic, the tunnels allow sea-going vessels passage into and out of the bay. A great deal of information is given on the project's home page, including a map of the surrounding area, historical perspectives, interesting facts, tourist attractions, and frequently asked questions. There are also a few pictures scattered throughout the site that show the enormity of the bridge-tunnel.

2002-01-01

306

The Higgs Bridge  

E-print Network

The particle recently discovered at the Large Hadron Collider near Geneva is almost certainly a Higgs boson, the long-sought completion of the Standard Model of particle physics. But this discovery, an achievement by more than six thousand scientists (including students), is actually much more than a mere capstone of the Standard Model. It instead represents a bridge from the Standard Model to exciting discoveries of the future, at higher energies or in other experiments, and to the properties of matter at very low temperatures. The mere existence of a particle with zero spin implies a need for new physics, with the most likely candidate being supersymmetry, which requires that every known particle has a superpartner yet to be discovered. And phenomena similar to the Higgs are seen in superconducting metals and superfluid gases at low temperatures, which extend down to a millionth or even a billionth of a degree Kelvin. So the discovery of a Higgs boson has a central place in our attempts both to achieve a true understanding of Nature and to harness Nature in practical applications.

Roland E. Allen

2013-11-11

307

Smart measurement system for resistive (bridge) or capacitive sensors  

NASA Astrophysics Data System (ADS)

A low-cost smart measurement system for resistive (bridge) and capacitive sensors is presented and demonstrated. The measurement system consists of three main parts: the sensor element, a universal transducer interface (UTI) and a microcontroller. The UTI is a sensor-signal-to-time converter, based on a period-modulated oscillator, which is equipped with front-ends for many types of resistive (bridge) and capacitive sensors, and which generates a microcontroller-compatible output signal. The microcontroller performs data acquisition of the output signals from the interface UTI, controls the working status of the UTI for a specified application and communicates with a personal computer. Continuous auto-calibration of the offset and the gain of the complete system is applied to eliminate many nonidealities. Experimental results show that the accuracy and resolution are 14 bits and 16 bits, respectively, for a measurement time of about 100 ms.

Wang, Guijie; Meijer, Gerard C. M.

1998-07-01

308

Performance of an angular flange aeroelastic wind energy converter  

SciTech Connect

ALL conventional wind turbines operate on the principles of turbomachinaries, with wind being made to flow over a set of rotating vanes. Recently, a new concept for wind energy conversion based on aeroelastic instability was introduced. It is well known that couplings between the vibration of an elastic structure and fluid stream may lead to aeroelastic instability. Energy then is transferred from the airstream into the elastic structure, which results in a destructive monotonic increase of the vibration amplitude of the structure. The failure of the Tacoma Narrows Bridge is one of the well-known examples of such a disaster. The use of an aeroelastic instability (or flutter) mechanism for constructing a wind energy converter was suggested. The theory for a torsional wind energy converter and the results of some model tests were also presented. Recently, some studies on similar types of wind energy converters using oscillating airfoils were reported. In the present study an angular flange H-section model of a torsional aeroelastic wind energy converter is constructed, and its performances under various conditions are investigated. The effects of the variations of the flange angle and the flange width on the performance of the model are studied. The weight of the pendulum is also varied, and its effects on the power coefficient of the model are investigated. It is observed that the efficiency of energy conversion decreases with an increase in wind speed. A method for possible improvement of the theoretical prediction is suggested and discussed.

Ahmadi, G.

1983-05-01

309

Mineral bridges in nacre revisited  

E-print Network

We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200 nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (> 100 nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (< 60 nm), earlier reported to be mineral bridges, found to be such.

Antonio G. Checa; Julyan H. E. Cartwright; Marc-Georg Willinger

2012-07-20

310

Mineral bridges in nacre revisited  

E-print Network

We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200 nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (> 100 nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (< 60 nm), earlier reported to be mineral bridges, found to be such.

Checa, Antonio G; Willinger, Marc-Georg

2012-01-01

311

SURROGATE BRIDGE FREEZING SRDJAN JANKOVIC  

E-print Network

for advanced bridge deck heating control strategies. In order to develop the "smart" control system, some data Department of Transportation and the Federal Highway Administration for funding this project. I also extend

312

Bridges, Switches, Routers 1.1 Introduction  

E-print Network

Chapter 1 Bridges, Switches, Routers 1.1 Introduction ¯ Packet vs circuit (and virtual circuit ¯ Packet processors--Bridges, Routers, ATM switches 1 #12;2 CHAPTER 1. BRIDGES, SWITCHES, ROUTERS Routing in an extended LAN. See Problem 2. #12;4 CHAPTER 1. BRIDGES, SWITCHES, ROUTERS Figure 1.3: LAN vs VLAN topology

Varaiya, Pravin

313

Geology Fieldnotes: Natural Bridges National Monument, Utah  

NSDL National Science Digital Library

This site describes how natural bridges form in crossbedded sandstone, the three stages of bridge maturity, and the differences between bridges and arches. Also included are photographs, park maps, visitor information, and details on the discovery of the Owachomo, Sipapu, and Kachina Bridges.

314

Effective plasmonic mode-size converter.  

PubMed

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

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

2011-10-24

315

Wind/water energy converter  

NASA Technical Reports Server (NTRS)

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

Paulkovich, J.

1979-01-01

316

Converting Technology into a Company  

E-print Network

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

Yang, Eui-Hyeok

317

Sacrificial bridges for MEMS fabrication  

NASA Astrophysics Data System (ADS)

This study discusses sacrificial bridges that are used to release MEMS devices. Before being released, sacrificial bridges connect all the component structures into an integral structure. Solder bump bonding is used to mount the MEMS chip on another chip or a printed circuit board (PCB) and to maintain the alignment among all component structures after removal of the sacrificial bridges. Two types of sacrificial bridges were designed, analyzed and fabricated. The fabrication process—which used low resistivity single crystal silicon (SCS) wafers as the device material—was developed to implement the sacrificial bridges. Novel SCS through silicon vias (TSVs), which interconnect stacked chips, was made using the same process. An electrostatic comb drive actuator was fabricated and mounted onto a PCB. The fabricated actuator was tested to demonstrate the feasibility of the fabrication process, sacrificial bridges and SCS TSVs. The results show that the actuator worked well. Its maximum displacement and resonant frequency were 69.9 µm and 406 Hz, respectively. This method is promising for the delivery of a novel 3D system in package for MEMS devices.

Chang, Chao-Min; Chen, Yang-Che; Fong, Chien-Fu; Guu, Yunn-Horng; Chen, Rongshun; Yeh, J. Andrew; Hou, Max T.

2011-09-01

318

HIGH EFFICIENCY AUXILIARY POWER CONVERTERS  

Microsoft Academic Search

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

Geoff Walker

319

A Binary Coded Decimal Converter  

Microsoft Academic Search

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

Martin Ziserman

1956-01-01

320

Bridges of RWRE Bridges of Random Walks in a Random Environment  

E-print Network

Bridges of RWRE Bridges of Random Walks in a Random Environment Jonathon Peterson Cornell Jonathon Peterson 2/25/2010 1 / 24 #12;Bridges of RWRE Introduction Bridges of Random Walks Sn simple on {S2n = 0}? Cornell University Jonathon Peterson 2/25/2010 2 / 24 #12;Bridges of RWRE Introduction

Peterson, Jonathon

321

SoftBridge: An Architecture for Building IP-based Bridges over the Digital Divide  

E-print Network

SoftBridge: An Architecture for Building IP-based Bridges over the Digital Divide John Lewis, Bill, effective communication between the different media has be able to bridge across these options: the bridges preferences and capabilities. Our research proposes a Soft- Bridge, an abstracted communications platform

Blake, Edwin

322

High efficiency converter with charge pump and coupled inductor for wide input photovoltaic AC module applications  

Microsoft Academic Search

Existing photovoltaic (PV) panels have widely varying input voltages based on the panel configuration and size. In this paper, a novel topology with a single active switch - combining boost, flyback, and charge-pump circuits - is proposed in order to achieve wide input range, high voltage gain, high efficiency, and low cost simultaneously. It meets the input-voltage and power-level needs

Wensong Yu; Chris Hutchens; Jih-Sheng Lai; Jianhui Zhang; Gianpaolo Lisi; Ali Djabbari; Greg Smith; Tim Hegarty

2009-01-01

323

MODELING OF HIGH-POWER-FACTOR RECTIFIERS BASED ON SWITCHING CONVERTERS  

E-print Network

Alter design. A line-frequency averaged model is presented for the purpose of designing the output flyback rectifier. 1 Introduction Nonlinear-carrier control (NLC) has recently been introduced for single-phase, high-power factor rectifiers [I, 21. The NLC control, with a block diagram shown in Fig. I, features

324

Control Design of a Three-Phase Matrix-Converter-Based AC–AC Mobile Utility Power Supply  

Microsoft Academic Search

This paper describes the control analysis and design of an ac-to-ac three-phase mobile utility power supply using a matrix converter capable of high-quality 50-, 60-, and 400-Hz output voltage and reduced input harmonic distortion. Instead of the traditional structure employing a diode bridge rectifier, a dc link and a pulsewidth-modulated inverter, a three-phase-to-three-phase direct ac-ac (matrix) converter has been used

Pericle Zanchetta; Patrick W. Wheeler; Jon C. Clare; Michael Bland; Lee Empringham; Dimosthenis Katsis

2008-01-01

325

The three-level ZVS PWM converter-a new concept in high voltage DC-to-DC conversion  

Microsoft Academic Search

A novel high-frequency DC-to-DC power converter for high-voltage and high power is introduced, which features zero voltage switching (ZVS) operation at constant frequency, regulation by pulse width modulation (PWM) and low RMS current stress upon power switches. Its greatest attribute, in comparison to the ZVS-PWM full bridge converter, is that the voltage across the switches is half the input voltage.

J. R. Pinheiro; I. Barbi

1992-01-01

326

The Influence of the Material of the Transformer Core on Characteristics of the Selected DC-DC Converters  

NASA Astrophysics Data System (ADS)

In the paper the influence of the ferromagnetic material used for the construction of the core of the impulse-transformer on the characteristics of a half-bridge converter is considered. The investigated network is described and some results of measurements are shown. On the basis of the obtained characteristics of the investigated converters some suggestions for the designers of such circuits are formulated.

Górecki, Krzysztof; Zar?bski, Janusz

327

A 1.6-kW, 110-kHz dc-dc converter optimized for IGBT's  

NASA Technical Reports Server (NTRS)

A full bridge dc-dc converter using a zero-current and zero-voltage switching technique is described. This circuit utilizes the characteristics of the IGBT to achieve power and frequency combinations that are much higher than previously reported for this device. Experimental results are included for a 1.6-kW, 110-kHz converter with 95 percent efficiency.

Chen, Keming; Stuart, Thomas A.

1993-01-01

328

Development of inspection robots for bridge cables.  

PubMed

This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented. PMID:24459453

Yun, Hae-Bum; Kim, Se-Hoon; Wu, Liuliu; Lee, Jong-Jae

2013-01-01

329

Test and evaluation of load converter topologies used in the Space Station Freedom power management and distribution dc test bed  

NASA Technical Reports Server (NTRS)

Power components hardware in support of the Space Station freedom dc Electric Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switch-mode converter, and a switching full-bridge forward converter. The topology, operation principles, and test results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.

Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.

1991-01-01

330

Test and evaluation of load converter topologies used in the Space Station Freedom Power Management and distribution DC test bed  

NASA Technical Reports Server (NTRS)

Power components hardware in support of the Space Station Freedom dc Electrical Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switchmode converter, and a switching full-bridge forward converter. The topology, operation principles, and tests results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.

Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.

1991-01-01

331

Non-Seismology Seismology: Using QuakeCatchers to Analyze the Frequency of Bridge Vibrations  

NASA Astrophysics Data System (ADS)

We conducted an experiment to test the feasibility of measuring seismic waves generated by traffic near James Madison University. We used QuakeCatcher seismometers (originally designed for passive seismic measurement) to measure vibrations associated with traffic on a wooden bridge as well as a nearby concrete bridge. This experiment was a signal processing exercise for a student research project and did not draw any conclusions regarding bridge safety or security. The experiment consisted of two temporary measurement stations comprised of a laptop computer and a QuakeCatcher - a small seismometer that plugs directly into the laptop via a USB cable. The QuakeCatcher was taped to the ground at the edge of the bridge to achieve good coupling, and vibrational events were triggered repeatedly with a control vehicle to accumulate a consistent dataset of the bridge response. For the wooden bridge, the resulting 'seismograms' were converted to Seismic Analysis Code (SAC) format and analyzed in MATLAB. The concrete bridge did not generate vibrations significant enough to trigger the recording mechanism on the QuakeCatchers. We will present an overview of the experimental design and frequency content of the traffic patterns, as well as a discussion of the instructional benefits of using the QuakeCatcher sensors in this non-traditional setting.

Courtier, A. M.; Constantin, C.; Wilson, C. F.

2013-12-01

332

26. NEW STEEL BRIDGE COMPLETED ASSEMBLED. OLD BRIDGE BELOW. U.S.G.S. ...  

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

26. NEW STEEL BRIDGE COMPLETED ASSEMBLED. OLD BRIDGE BELOW. U.S.G.S. GAGING STATION IN RIGHT BACKGROUND. VIEW LOOKING NORTHEAST - Kaibab Trail Suspension Bridge, Spanning Colorado River, Grand Canyon, Coconino County, AZ

333

Design of a bridge bumper to protect bridge girders against collisions of overheight vehicles  

E-print Network

of the damaged bridges can be costly and time consuming. This research investigates the feasibility of developing a bridge bumper that minimizes the physical injuries and the likelihood of fatalities and protects the structural elements of bridges by absorbing...

Sharma, Hrishikesh

2009-05-15

334

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2011-10-01

335

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2013-10-01

336

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2010-10-01

337

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312...Interlocking Standards § 236.312 Movable bridge, interlocking of signal appliances with...

2012-10-01

338

East elevation of lift bridge, with U.S. Rt. 11 bridge ...  

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

East elevation of lift bridge, with U.S. Rt. 11 bridge in background. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD

339

Characterization of the Dual-Active Bridge topology for high-power applications employing a duty-cycle modulation  

Microsoft Academic Search

In the present paper the dual-active bridge topology employing a duty-cycle modulation is studied. The behavior of the converter at steady-state is examined. Additionally, the small-signal model of the topology is presented and the dynamic behavior is examined. Simulations and experimental results are presented. It is worth noticing that the converter is operated under softs-witching conditions in a wide load

Georgios D. Demetriades; Hans-Peter Nee

2008-01-01

340

New converter circuitry for PV applications using multilevel converters  

Microsoft Academic Search

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

Mostafa Mousa; Mahrous E. Ahmed; M. Orabi

2009-01-01

341

Bridging the Vector Calculus Gap  

NSDL National Science Digital Library

This paper was written collaboratively by a physicist and a mathematician to raise awareness about the "vector calculus gap" and offer realistic solutions to bridge the gap. The authors define the vector calculus gap as a disparity between the way mathematicians and physical scientists think about vectors, which they argue results in performance difficulties for students of physics and engineering. In this paper, they advocate emphasizing geometric reasoning over algebraic computation when introducing vectors. In addition, their proposed instructional method uses differentials to bridge the vector calculus gap. Included are sample group activities and tips for incorporating these ideas in the classroom. SEE RELATED ITEMS BELOW for a link to the authors' full web site on Bridging the Vector Calculus Gap.

Dray, Tevian; Manogue, Corinne A.

2008-12-23

342

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

343

Convertible Gas-Turbine Engines  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

344

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

345

Bridge Construction and Engineering Learning Center  

NSDL National Science Digital Library

This website is a great resource for information on bridges. The site provides links to websites like PBS's Nova, where you can learn about different types of bridges and then test your knowledge by matching the right bridge to the right location (over a freeway, river, canyon or ocean waterway), or where you can read more about the forces, loads and materials that affect bridges. Another link takes you to Better Bridges, where you can find out how many bridges are in your state. Definitely a great resource for those armchair engineers but also for teachers and students of physics looking for some great information on this fascinating type of construction.

346

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

347

Excitation Methods for Bridge Structures  

SciTech Connect

This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.

Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.

1999-02-08

348

Balanced bridge feedback control system  

NASA Technical Reports Server (NTRS)

In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.

Lurie, Boris J. (inventor)

1990-01-01

349

Stochastic bridges of linear systems  

E-print Network

We study a generalization of the Brownian bridge as a stochastic process that models the position and velocity of inertial particles between the two end-points of a time interval. The particles experience random acceleration and are assumed to have known states at the boundary. Thus, the movement of the particles can be modeled as an Ornstein-Uhlenbeck process conditioned on position and velocity measurements at the two end-points. It is shown that optimal stochastic control provides a stochastic differential equation (SDE) that generates such a bridge as a degenerate diffusion process. Generalizations to higher order linear diffusions are considered.

Yongxin Chen; Tryphon Georgiou

2014-07-12

350

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

351

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

352

New ?-? voltage to frequency converter  

Microsoft Academic Search

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

Milan Stork

2002-01-01

353

Parametric study of laser photovoltaic energy converters  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

354

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

Microsoft Academic Search

Three new dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. Of the three circuits the single-phase and three-phase versions of the dual-active-bridge topology demonstrate minimal

Kheraluwala

1991-01-01

355

An improved energy recovery clamp circuit for PWM converters with a wide range of input voltage  

Microsoft Academic Search

A full-bridge dc-dc converter employing diode rectifier in the output experiences severe voltage overshoot and oscillation problem across the diode rectifier caused by the interaction between the junction capacitance of the rectifier diode and the leakage inductance of transformer. The pronounced reverse-recovery current of high power diodes enforces these issues significantly by increasing power loss and voltage overshoot. Conventional energy

Honnyong Cha; Lihua Chen; Fang Z. Peng; Qingsong Tang

2007-01-01

356

A Three-Phase Controlled-Current PWM Converter with Leading Power Factor  

Microsoft Academic Search

Experimental tests performed on a three-phase bipolartransistor controlled-current PWM power modulator show that it can operate with near-sinusoidal currents at 60 Hz with a 360-degree power angle range. Because of its capability to operate with leading power factor and good waveform, the PWM converter is a promising alternative to the thyristor Graetz bridge. A theoretical method based on the concept

Boon Teck Ooi; John C. Salmon; Juan W. Dixon; Ashok B. Kulkarni

1987-01-01

357

Combined deadbeat control of a series-parallel converter combination used as a universal power filter  

Microsoft Academic Search

This paper presents the notion of combined control of a system of interconnected power electronic converters. The concept is demonstrated using a three-phase series-parallel active power filter as an example. The described active power filter consists of a series-parallel combination of two full bridge VSIs capable of arbitrarily controlling the input current and output voltage. The proposed control scheme treats

Farrukh Kamran; Thomas G. Habetler

1998-01-01

358

NASA Now: Operation IceBridge  

NASA Video Gallery

During this NASA Now program, you'??ll meet Michael Studinger, Project Scientist for Operation IceBridge. He'??ll describe the purpose of the IceBridge campaign and how the campaign objectives will...

359

Performance Analysis of LAN Bridges and Routers.  

National Technical Information Service (NTIS)

Bridges and routers are used to interconnect Local Area Networks (LANs). The performance of these devices is important since they can become bottlenecks in large multi-segment networks. Performance metrics and test methodology for bridges and routers were...

A. R. Hajare

1991-01-01

360

Approach to Setting Bridge Crossing Rating Criteria.  

National Technical Information Service (NTIS)

Document describes a methodology for rating bridges for non-normal crossing conditions. This methodology is based on probability of failure calculations, for normal crossings, for the recommended caution crossing rating the bridge will have the same proba...

P. D. Hilton, P. R. Nayak

1983-01-01

361

Wind effect on long span bridge  

E-print Network

This thesis has studied different types of reactions of long span bridge under wind load, such as vortex shedding, flutter and buffeting. Since all of these conditions have the chance to damage bridge structure, we calculate ...

Zhang, Xi, M. Eng. Massachusetts Institute of Technology

2012-01-01

362

Seismic Design of Monolithic Bridge Abutments,  

National Technical Information Service (NTIS)

The objective of the research was to investigate the soil-structure interaction characteristics between monolithic bridge abutments and the surrounding soil. The investigation consisted of: (1) vibration tests on the Horsethief Bridge, a single span struc...

B. Hushmand, C. B. Crouse, G. Liang, G. Martin, J. Wood

1986-01-01

363

Determination of Bridge Response Using Acceleration Data.  

National Technical Information Service (NTIS)

Knowledge of the actual displacement response of a bridge subjected to random traffic loading is useful in evaluating bridge performance and serviceability. However, mounting displacement transducers is difficult, and the feasibility of and cost associate...

B. C. Faulkner, F. W. Barton, T. T. Baber, W. T. McKeel

1996-01-01

364

Bridges on the River Quad  

NSDL National Science Digital Library

In this activity, students graph a quadratic function that models the shape of a bridge trestle and then solve the related quadratic equation by completing the square. Students use the calculatorsâ capabilities to find the x-intercepts and the maximum value on the graph. Teacher notes, detailed instructions on using graphing calculators, and questions to check comprehension aid in teaching the lesson.

2011-03-27

365

A Bridge to the Future  

ERIC Educational Resources Information Center

Career and technical education (CTE) has a promising future at Darlington (WI) High School. In this article, the author describes how a class bridge project became a real-world, project-based learning opportunity involving higher-level thinking skills that are at the core of CTE at his school. It began when a local citizen approached him at the…

Anderson, Richard

2008-01-01

366

The Bridge to Manufacturing Project  

ERIC Educational Resources Information Center

A grant project was designed to facilitate the transition of students from a community college adult education program into a community college credit-degree program in manufacturing. Key features of the program included a focus on identifying policy implications; bridging the separation between the adult education segment of the community college…

Puchner, Laurel; Taylor, Ann R.; Harris, Valorie K.; Marshall, Rick W.; Powell, Margaret

2010-01-01

367

WSC Bridge Program Planning Guide  

ERIC Educational Resources Information Center

Increasingly jobs that pay more than subsistence wages and offer opportunities for career advancement require at least some training beyond high school, even at the entry level. Bridge training programs are designed to prepare individuals without the requisite basic skills for postsecondary training leading to career-path employment and further…

Jenkins, Davis

2004-01-01

368

to China: A Bridge Between  

E-print Network

From Yale to China: A Bridge Between Cultures Students often invoke the metaphor of a journey in China," she said. "Yale oered a vast array of resources to help me improve my language compe- tency program and myriad exchanges with China. The summer before her sophomore year at Yale, Jenna received

369

Bridge Funding Program 2007 Awardees  

E-print Network

Reactivity Model for Assessing Pharmacologic Intervention in Treatment of Cannabis Use Disorders Ananda-Assisted Integrated Approach for Enhancing Bridge Health Monitoring Guri Tzivion, Pathology Regulation of c-Raf-1 on Preimplantation Mouse Development Melissa Runge-Morris, Institute of Environmental Health Sciences

Berdichevsky, Victor

370

"Sand Boil" on Bay Bridge  

USGS Multimedia Gallery

"Sand boil" or sand volcano measuring 2 m (6.6 ft) in length erupted in median of Interstate Highway 80 west of the Bay Bridge toll plaza when ground shaking transformed loose water-saturated deposit of subsurface sand into a sand-water slurry (liquefaction). Vented sand contains-marine shell f...

2009-01-26

371

NONLINEAR AERODYNAMIC ANALYSIS OF BRIDGES UNDER TURBULENT WINDS: THE NEW FRONTIER IN BRIDGE  

E-print Network

with the conventional linear approach is made through response analysis of a long-span suspension bridge. KEYWORDSNONLINEAR AERODYNAMIC ANALYSIS OF BRIDGES UNDER TURBULENT WINDS: THE NEW FRONTIER IN BRIDGE. In this study, a time domain analysis framework for predicting the flutter and buffeting responses of bridges

Kareem, Ahsan

372

Bridge Programs in Illinois: Results of the 2010 Illinois Bridge Status Survey  

ERIC Educational Resources Information Center

This report provides a summary of major results of the Illinois Bridge Status Survey, administered online between April and June 2010. The purpose of the survey was to understand the extent to which bridge programs are being implemented in Illinois, as well as to build an online directory of bridge programs. Bridge programs are an emerging…

Taylor, J. L.; Harmon, T.

2010-01-01

373

47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Watch required by the Bridge-to-Bridge Act. 80.309 Section 80.309 Telecommunication...Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch...

2011-10-01

374

47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Operator requirements of the Bridge-to-Bridge Act. 80.163 Section 80.163 Telecommunication...Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the...

2013-10-01

375

47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Operator requirements of the Bridge-to-Bridge Act. 80.163 Section 80.163 Telecommunication...Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the...

2012-10-01

376

47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Operator requirements of the Bridge-to-Bridge Act. 80.163 Section 80.163 Telecommunication...Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the...

2010-10-01

377

47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Watch required by the Bridge-to-Bridge Act. 80.309 Section 80.309 Telecommunication...Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch...

2013-10-01

378

47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Operator requirements of the Bridge-to-Bridge Act. 80.163 Section 80.163 Telecommunication...Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the...

2011-10-01

379

47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Watch required by the Bridge-to-Bridge Act. 80.309 Section 80.309 Telecommunication...Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch...

2010-10-01

380

47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Watch required by the Bridge-to-Bridge Act. 80.309 Section 80.309 Telecommunication...Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch...

2012-10-01

381

49 CFR 237.33 - Content of bridge management programs.  

Code of Federal Regulations, 2010 CFR

...33 Content of bridge management programs. Each bridge management program adopted in compliance...bridge, its location, configuration, type of construction...necessary to provide for the management of bridge safety;...

2010-10-01

382

49 CFR 237.103 - Bridge inspection procedures.  

Code of Federal Regulations, 2013 CFR

... 4 2013-10-01 2013-10-01 false Bridge inspection procedures. 237.103 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.103 Bridge inspection...

2013-10-01

383

49 CFR 237.53 - Railroad bridge inspectors.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Railroad bridge inspectors. 237.53 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.53 Railroad bridge inspectors. A railroad bridge...

2012-10-01

384

49 CFR 237.53 - Railroad bridge inspectors.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Railroad bridge inspectors. 237.53 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.53 Railroad bridge inspectors. A railroad bridge...

2010-10-01

385

49 CFR 237.103 - Bridge inspection procedures.  

Code of Federal Regulations, 2010 CFR

... 4 2010-10-01 2010-10-01 false Bridge inspection procedures. 237.103 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.103 Bridge inspection...

2010-10-01

386

23 CFR 650.807 - Bridges requiring a USCG permit.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Bridges requiring a USCG permit. 650.807... ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges requiring a...

2012-04-01

387

49 CFR 237.111 - Review of bridge inspection reports.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Review of bridge inspection reports. 237.111 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.111 Review of bridge...

2010-10-01

388

23 CFR 650.807 - Bridges requiring a USCG permit.  

...2014-04-01 2014-04-01 false Bridges requiring a USCG permit. 650.807... ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges requiring a...

2014-04-01

389

49 CFR 237.111 - Review of bridge inspection reports.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Review of bridge inspection reports. 237.111 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.111 Review of bridge...

2011-10-01

390

49 CFR 237.107 - Conduct of bridge inspections.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Conduct of bridge inspections. 237.107 Section 237.107 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.107 Conduct of bridge...

2013-10-01

391

49 CFR 237.107 - Conduct of bridge inspections.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Conduct of bridge inspections. 237.107 Section 237.107 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.107 Conduct of bridge...

2012-10-01

392

23 CFR 650.807 - Bridges requiring a USCG permit.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bridges requiring a USCG permit. 650.807... ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges requiring a...

2013-04-01

393

49 CFR 237.103 - Bridge inspection procedures.  

Code of Federal Regulations, 2011 CFR

... 4 2011-10-01 2011-10-01 false Bridge inspection procedures. 237.103 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.103 Bridge inspection...

2011-10-01

394

33 CFR 118.90 - Bridges crossing channel obliquely.  

Code of Federal Regulations, 2013 CFR

...Waters 1 2013-07-01 2013-07-01 false Bridges crossing channel obliquely. 118.90 Section 118...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges...

2013-07-01

395

33 CFR 118.90 - Bridges crossing channel obliquely.  

Code of Federal Regulations, 2012 CFR

...Waters 1 2012-07-01 2012-07-01 false Bridges crossing channel obliquely. 118.90 Section 118...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges...

2012-07-01

396

49 CFR 237.111 - Review of bridge inspection reports.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Review of bridge inspection reports. 237.111 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.111 Review of bridge...

2013-10-01

397

49 CFR 237.107 - Conduct of bridge inspections.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Conduct of bridge inspections. 237.107 Section 237.107 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.107 Conduct of bridge...

2011-10-01

398

49 CFR 237.107 - Conduct of bridge inspections.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Conduct of bridge inspections. 237.107 Section 237.107 ...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.107 Conduct of bridge...

2010-10-01

399

49 CFR 237.53 - Railroad bridge inspectors.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Railroad bridge inspectors. 237.53 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.53 Railroad bridge inspectors. A railroad bridge...

2013-10-01

400

23 CFR 650.807 - Bridges requiring a USCG permit.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Bridges requiring a USCG permit. 650.807... ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.807 Bridges requiring a...

2011-04-01

401

33 CFR 118.90 - Bridges crossing channel obliquely.  

Code of Federal Regulations, 2011 CFR

...Waters 1 2011-07-01 2011-07-01 false Bridges crossing channel obliquely. 118.90 Section 118...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges...

2011-07-01

402

33 CFR 118.90 - Bridges crossing channel obliquely.  

Code of Federal Regulations, 2010 CFR

...Waters 1 2010-07-01 2010-07-01 false Bridges crossing channel obliquely. 118.90 Section 118...Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges...

2010-07-01

403

49 CFR 237.109 - Bridge inspection records.  

Code of Federal Regulations, 2013 CFR

... 4 2013-10-01 2013-10-01 false Bridge inspection records. 237.109 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.109 Bridge inspection...

2013-10-01

404

49 CFR 237.103 - Bridge inspection procedures.  

Code of Federal Regulations, 2012 CFR

... 4 2012-10-01 2012-10-01 false Bridge inspection procedures. 237.103 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.103 Bridge inspection...

2012-10-01

405

49 CFR 237.111 - Review of bridge inspection reports.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Review of bridge inspection reports. 237.111 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.111 Review of bridge...

2012-10-01

406

49 CFR 237.109 - Bridge inspection records.  

Code of Federal Regulations, 2012 CFR

... 4 2012-10-01 2012-10-01 false Bridge inspection records. 237.109 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.109 Bridge inspection...

2012-10-01

407

49 CFR 237.53 - Railroad bridge inspectors.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Railroad bridge inspectors. 237.53 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Qualifications and...Responsible Persons § 237.53 Railroad bridge inspectors. A railroad bridge...

2011-10-01

408

Conservation of Salt Bridges in Protein Families  

Microsoft Academic Search

A detailed computational analysis is presented that focuses on the relationship between structural attributes and the degree and mode of salt bridge conservation. A data set of conserved and non-conserved salt bridges was constructed from eight protein families, based on the structural alignment of family members. Salt bridges were defined at the secondary structure level rather than at the residue

Ora Schueler; Hanah Margalit

1995-01-01

409

Building Bridges One Line at a Time  

ERIC Educational Resources Information Center

In this article, first-grade students were taught the different kinds of lines that were part of the construction of various bridges--the curved lines of the arches of stone bridges, straight lines connecting the cables of a suspension bridge, vertical lines, horizontal lines, and so on. They gained practice in drawing structures and in fine brush…

Grigsby, Cathy Murray

2012-01-01

410

Imaging radar for bridge deck inspection  

Microsoft Academic Search

Lawrence Livermore National Laboratory is developing a prototype imaging radar for inspecting steel reinforced concrete bridge decks. The system is designed to acquire synthetic aperture radar data and provide high-resolution images of internal structure, flaws, and defects enabling bridge inspectors to nondestructively evaluate and characterized bridge deck condition. Concrete delamination resulting from corrosion of steel reinforcing bars (rebars) is an

John P. Warhus; Jeffrey E. Mast; Scott D. Nelson

1995-01-01

411

Removal of failed crown and bridge  

PubMed Central

Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in completing restorative/endodontic procedures. There are different mechanisms available to remove a failed crown or bridge. But there is no information published about the classification of available systems for crown and bridge removal. So it is logical to classify these systems into different groups which can help a clinician in choosing a particular type of system depending upon the clinical situation. The aim of this article is to provide a classification for various crown and bridge removal systems; describe how a number of systems work; and when and why they might be used. A PubMed search of English literature was conducted up to January 2010 using the terms: Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. Additionally, the bibliographies of 3 previous reviews, their cross references as well as articles published in various journals like International Endodontic Journal, Journal of Endodontics and were manually searched. Key words:Crown and bridge removal, Crown and bridge disassembly, Crown and bridge failure. PMID:24558549

Rahul, G R.; Poduval, Soorya T.; Shetty, Karunakar

2012-01-01

412

Dynamic response of highway girder bridges  

Microsoft Academic Search

The objective of the paper is to investigate the variation of dynamic loading of girder bridges with different girder number and span length due to several vehicles moving across rough bridge decks. Nine girder bridges with girder number ranging from four to eight and span length changing from 40 to 120 ft are designed based on the AASHTO standard highway

Ton-Lo Wang; Dongzhou Huang; Mohsen Shahawy; Kaizan Huang

1996-01-01

413

Simulation of multivariate diffusion bridges Mogens Bladt  

E-print Network

Simulation of multivariate diffusion bridges Mogens Bladt Instituto de Investigacion en Matem Abstract We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental simulation method for one-dimensional bridges to the multi-variate setting. First a method of simulating

Sørensen, Michael

414

MARKOVIAN BRIDGES: WEAK CONTINUITY AND PATHWISE CONSTRUCTIONS  

E-print Network

MARKOVIAN BRIDGES: WEAK CONTINUITY AND PATHWISE CONSTRUCTIONS LO¨IC CHAUMONT AND GER´ONIMO URIBE BRAVO Abstract. A Markovian bridge is a probability measure taken from a disintegration of the law of an initial part of the path of a Markov process given its terminal value. As such, Markovian bridges admit

Paris-Sud XI, Université de

415

PALESTRA -PPGEC Efficient Management of Bridges  

E-print Network

PALESTRA - PPGEC Efficient Management of Bridges Ales Znidaric Slovenian National Building and Civil Engineering Institute Dia: 26/03/2012 Hora: 14:00 Local: Auditório PPGEC #12;Resumo: Bridges planning of rehabilitation measures is often difficult as bridges deteriorate while loading over time

Floeter, Sergio Ricardo

416

Remediation: Higher Education's Bridge to Nowhere  

ERIC Educational Resources Information Center

The intentions were noble. It was hoped that remediation programs would be an academic bridge from poor high school preparation to college readiness. Sadly, remediation has become instead higher education's "Bridge to Nowhere." This broken remedial bridge is travelled by some 1.7 million beginning students each year, most of whom will not reach…

Complete College America, 2012

2012-01-01

417

CONVEX, ROTATIONALLY SYMMETRIC LIQUID BRIDGES BETWEEN SPHERES  

E-print Network

CONVEX, ROTATIONALLY SYMMETRIC LIQUID BRIDGES BETWEEN SPHERES Thomas I. Vogel Department of Mathematics Texas A&M University College Station, TX 77843 tvogel@math.tamu.edu A liquid bridge between two different contact an- gles: one for each ball). If we consider rotationally symmetric bridges, then the free

Vogel, Thomas

418

A Participatory Public Art Project: Community Bridge  

ERIC Educational Resources Information Center

This article introduces Community Bridge, a participatory public art project that brought together artists and residents to address aesthetic needs of an urban environment. The Community Bridge is an exemplary work of art by American artist William Cochran. In addition to creating a natural gathering place for residents of all ages, the bridge is…

Stephens, Pam

2005-01-01

419

MELISSA E. BRIDGES melbrid@gmail.com  

E-print Network

MELISSA E. BRIDGES melbrid@gmail.com Education: Ph.D. Ecology and Environmental Sciences Expected, South Carolina Professional Development (Selected Publications and Presentations): Bridges, M., B]. Bridges, M., B.D. Maxwell, J. Rotella, and L.J. Rew. 2009. Evaluating the relationship between invasive

Maxwell, Bruce D.

420

ADVANCED COMPOSITE MATERIALS FOR BRIDGES Sami RIZKALLA  

E-print Network

1. SUMMARY ADVANCED COMPOSITE MATERIALS FOR BRIDGES Sami RIZKALLA ISIS Canada Network of Centres bridges are being built with materials that have significantly higher strength in comparison to steel associated with concrete bridges due to the corrosion of steel reinforcements. This paper presents

421

2014 APPLICATION FORM BRIDGING TRIBAL COLLEGE STUDENTS TO MONTANA STATE UNIVERSITY (BRIDGES)  

E-print Network

and a suspension bridge? Which type permits a longer span? Give three different types of bridges and the span is the average speed of the bicyclists in mi/hr and ft/s. Bridges What's the difference between a steel truss that is typical for each type of bridge. What is the most common type of bridge? Why is it so common? Is this type

422

Performance analysis of LAN bridges and routers  

NASA Technical Reports Server (NTRS)

Bridges and routers are used to interconnect Local Area Networks (LANs). The performance of these devices is important since they can become bottlenecks in large multi-segment networks. Performance metrics and test methodology for bridges and routers were not standardized. Performance data reported by vendors is not applicable to the actual scenarios encountered in an operational network. However, vendor-provided data can be used to calibrate models of bridges and routers that, along with other models, yield performance data for a network. Several tools are available for modeling bridges and routers - Network II.5 was used. The results of the analysis of some bridges and routers are presented.

Hajare, Ankur R.

1991-01-01

423

Theory of water and charged liquid bridges  

E-print Network

The phenomena of liquid bridge formation due to an applied electric field is investigated. A new solution for the charged catenary is presented which allows to determine the static and dynamical stability conditions where charged liquid bridges are possible. The creeping height, the bridge radius and length as well as the shape of the bridge is calculated showing an asymmetric profile in agreement with observations. The flow profile is calculated from the Navier Stokes equation leading to a mean velocity which combines charge transport with neutral mass flow and which describes recent experiments on water bridges.

Klaus Morawetz

2011-07-03

424

Human Lung Angiotensin Converting Enzyme  

PubMed Central

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

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

1981-01-01

425

Low Head, Vortex Induced Vibrations River Energy Converter  

SciTech Connect

Vortex Induced Vibrations Aquatic Clean Energy (VIVACE) is a novel, demonstrated approach to extracting energy from water currents. This invention is based on a phenomenon called Vortex Induced Vibrations (VIV), which was first observed by Leonardo da Vinci in 1504AD. He called it ‘Aeolian Tones.’ For decades, engineers have attempted to prevent this type of vibration from damaging structures, such as offshore platforms, nuclear fuel rods, cables, buildings, and bridges. The underlying concept of the VIVACE Converter is the following: Strengthen rather than spoil vortex shedding; enhance rather than suppress VIV; harness rather than mitigate VIV energy. By maximizing and utilizing this unique phenomenon, VIVACE takes this “problem” and successfully transforms it into a valuable resource for mankind.

Bernitsas, Michael B.; Dritz, Tad

2006-06-30

426

A Hybrid Energy System Using Cascaded H-bridge Converter , Zhong Du2  

E-print Network

proposes a hybrid energy system to integrate the variable-speed wind turbine, fuel cell, and battery using if the rest of energy sources are diminished, resulting in increased robustness. Another advantage-speed wind turbine, fuel cell, and battery as an energy storage element. As shown in Fig. 2, the speed

Tolbert, Leon M.

427

Disulfide Bridges Remain Intact while Native Insulin Converts into Amyloid Fibrils  

PubMed Central

Amyloid fibrils are ?-sheet-rich protein aggregates commonly found in the organs and tissues of patients with various amyloid-associated diseases. Understanding the structural organization of amyloid fibrils can be beneficial for the search of drugs to successfully treat diseases associated with protein misfolding. The structure of insulin fibrils was characterized by deep ultraviolet resonance Raman (DUVRR) and Nuclear Magnetic Resonance (NMR) spectroscopy combined with hydrogen-deuterium exchange. The compositions of the fibril core and unordered parts were determined at single amino acid residue resolution. All three disulfide bonds of native insulin remained intact during the aggregation process, withstanding scrambling. Three out of four tyrosine residues were packed into the fibril core, and another aromatic amino acid, phenylalanine, was located in the unordered parts of insulin fibrils. In addition, using all-atom MD simulations, the disulfide bonds were confirmed to remain intact in the insulin dimer, which mimics the fibrillar form of insulin. PMID:22675475

Kurouski, Dmitry; Washington, Jacqueline; Ozbil, Mehmet; Prabhakar, Rajeev; Shekhtman, Alexander; Lednev, Igor K.

2012-01-01

428

Comparative Study of Power Factor Correction Converters For Single Phase Half-Bridge Inverters  

E-print Network

. The diode rectifier on the front end causes seri- ous harmonic pollution to the utility as the number of UPSs increases. The other disadvantage resultes from the direct connection of the storage battery to the dc bus. Many battery cells connected in series are required to support a high dc bus voltage, which

Tolbert, Leon M.

429

A 1MHz, 12-V ZVS Nonisolated Full-Bridge VRM With Gate Energy Recovery  

Microsoft Academic Search

In this paper, a new self-driven zero-voltage-switching (ZVS) nonisolated full-bridge converter is presented for 12-V input VRM applications. The advantages of the new circuit are: 1) duty cycle extension; 2) ZVS of all the control MOSFETs; 3) lower voltage stress and reduced reverse recovery loss of the synchronous rectifier (SR) MOSFETs; 4) high-drive voltage to reduce R DS( ON) and

Zhiliang Zhang; Eric Meyer; Yan-Fei Liu; Paresh C. Sen

2010-01-01

430

Redesign of the SNS Modulator H-Bridge for Utilization of Press-Pack IGBTs  

SciTech Connect

The power conversion group at SLAC is currently redesigning the H-bridge switch plates of the High Voltage Converter Modulators at the Spallation Neutron Source. This integral part to the modulator operation has been indentified as a source of several modulator faults and potentially limits reliability with pulse width modulation operation. This paper is a presentation of the design and implementation of a redesigned switch plate based upon press-pack IGBTs.

Kemp, Mark A.; Burkhart, Craig; /SLAC; Anderson, David E.; /Oak Ridge

2008-09-25

431

Robot-Assisted Bridge Inspection  

Microsoft Academic Search

The Center for Robot-Assisted Search and Rescue (CRASAR®) deployed a customized AEOS man-portable unmanned surface vehicle\\u000a and two commercially available underwater vehicles (the autonomous YSI EcoMapper and the tethered VideoRay) for inspection\\u000a of the Rollover Pass bridge in the Bolivar peninsula of Texas in the aftermath of Hurricane Ike. A preliminary domain analysis\\u000a with the vehicles identified key tasks in

Robin R. Murphy; Eric Steimle; Michael Hall; Michael Lindemuth; David Trejo; Stefan Hurlebaus; Zenon Medina-Cetina; Daryl Slocum

432

Bridging Nonliving and Living Matter  

Microsoft Academic Search

Assembling non-biological materials (geomaterials) into a proto-organism constitutes a bridge between nonliving and living matter. In this article we present a simple step-by-step route to assemble a proto-organism. Many pictures have been proposed to describe this transition within the origins-of-life and artificial life communities, and more recently alternative pictures have been emerging from advances in nanoscience and biotechnology. The proposed

Steen Rasmussen; Liaohai Chen; Martin Nilsson; Shigeaki Abe

2003-01-01

433

Halliburton Composite Bridge Plug Assembly  

SciTech Connect

The overall objectives of this CRADA were to assist Halliburton in analyzing a composite bridge plug and to determine why their original design was failing in the field. In Phase 1, finite element analyses were done on the original composite slip design and several alternative designs. The composite slip was the component in the bridge plug that was failing. The finite element code ABAQUS was used for these calculations and I-DEAS was used as the pre- and post-processor in the analyses. Several different designs and materials were analyzed and recommendations were made towards improving the design. In Phase 2, the objective was to develop finite element models that would accurately represent the deformations in the entire all-composite 4-1/2' diameter bridge plug assembly. The finite element code LS-DYNA was used and the results from this effort were intended to expand Halliburton's composite design and analysis capabilities with regard to developing future composite components for downhole tools. In addition to the finite element modeling, this effort involved the utilization of micromechanics to determine the necessary composite material properties that were needed as input for finite element codes.

Starbuck, J.M.; Luttrell, C.R.; Aramayo, G.

2005-01-15

434

Cell modulated DC/DC converter  

E-print Network

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

Warren, James Raymond, III

2005-01-01

435

A study of DC-DC converters with MCT's for arcjet power supplies  

NASA Technical Reports Server (NTRS)

Many arcjet DC power supplies use PWM full bridge converters with large arrays of parallel FET's. This report investigates an alternative supply using a variable frequency series resonant converter with small arrays of parallel MCT's (metal oxide semiconductor controlled thyristors). The reasons for this approach are to: increase reliability by reducing the number of switching devices; and decrease the surface mounting area of the switching arrays. The variable frequency series resonant approach is used because the relatively slow switching speed of the MCT precludes the use of PWM. The 10 kW converter operated satisfactorily with an efficiency of over 91 percent. Test results indicate this efficiency could be increased further by additional optimization of the series resonant inductor.

Stuart, Thomas A.

1994-01-01

436

A Compact, Soft-Switching DC-DC Converter for Electric Propulsion  

NASA Technical Reports Server (NTRS)

A hybrid, soft-switching, DC-DC converter has been developed with superior soft switching characteristics, high efficiency, and low electro-magnetic interference. This hybrid topology is comprised of an uncontrolled bridge operating at full pulse-width, and a controlled section operating as a conventional phase modulated converter. The unique topology is able to maintain zero voltage switching down to no load operating conditions. A breadboard prototype was developed and tested to demonstrate the benefits of the topology. Improvements were then made to reduce the size of passive components and increase efficiency in preparation for packaging. A packaged prototype was then designed and built, and several innovative packaging techniques are presented. Performance test data is presented that reveals deficiencies in the design of the power transformer. A simple redesign of the transformer windings eliminated the deficiency. Future plans to improve the converter and packaging design are presented along with several conclusions.

Button, Robert; Redilla, Jack; Ayyanar, Raja

2003-01-01

437

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

438

Scour assessment at bridges from Flag Point to Million Dollar Bridge, Copper River Highway, Alaska  

USGS Publications Warehouse

Twelve bridges are located along the Copper River Highway from Flag Point (Mile 27) to lhe Million Dollar Bridge (Mile 48). These bridges cross all or parts of the Copper River. Channel scour at these bridges was assessed by collecting and analyzing discharge and sediment data, analyzing aerial photography for eight different years, surveying and comparing cross sections, and utilizing scour equations. Between 1968 and 1992, scour occurring at Bridge 331 has formed two distinct channels at the bridge. The channel at Bridge 1187 has remained relatively unchanged between 1968 and 1992. During this same time period, the channel at Bridge 332 appears to have gradually filled. However, during the 1992 runoff season, the channel at this bridge scoured significantly, probably because of its unstable nature. The most significant scour has occurred at Bridge 342. A high-water period in 1981 probably shifted much of the flow of the Copper River through this bridge. As a result, severe contraction scour occurred which required major repairs to the bridge. During 1991 and 1992, the approach channel to Bridge 342 has been migrating, causing scour in the left side of the channel. Bed material at the Million Dollar Bridge consists of hard unweathered boulders nested in dense gravel. Because of this type of erosion-resistant material, no significant scour has occurred at this site. Contraction scour equations overestimated the mean depth of flow at Bridge 331 by 2.6 to 5.0 ft, but were within 1.0 ft of the mean depth of flow for Bridge 1187. The local scour equations generally overestimated local scour at both Bridge 331 and Bridge 1187. The accuracy of some equations was probably affected because water velocities could not be obtained upstream from the piers.

Brabets, T. P.

1994-01-01

439

Heat flow in a pyroelectric converter  

Microsoft Academic Search

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

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

1985-01-01

440

Electromagnetic Compatibility of Matrix Converter System  

Microsoft Academic Search

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

Ji?í Lettl; Stanislav Flígl

441

Nonlinear-optic IR radiation converters  

NASA Astrophysics Data System (ADS)

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

Gainer, Aleksandr V.

442

Salt Bridges: Geometrically Specific, Designable Interactions  

PubMed Central

Salt bridges occur frequently in proteins, providing conformational specificity and contributing to molecular recognition and catalysis. We present a comprehensive analysis of these interactions in protein structures by surveying a large database of protein structures. Salt bridges between Asp or Glu and His, Arg, or Lys display extremely well-defined geometric preferences. Several previously observed preferences are confirmed and others that were previously unrecognized are discovered. Salt bridges are explored for their preferences for different separations in sequence and in space, geometric preferences within proteins and at protein-protein interfaces, cooperativity in networked salt bridges, inclusion within metal-binding sites, preference for acidic electrons, apparent conformational side chain entropy reduction upon formation, and degree of burial. Salt bridges occur far more frequently between residues at close than distant sequence separations, but at close distances there remain strong preferences for salt bridges at specific separations. Specific types of complex salt bridges, involving three or more members, are also discovered. As we observe a strong relationship between the propensity to form a salt bridge and the placement of salt-bridging residues in protein sequences, we discuss the role that salt bridges might play in kinetically influencing protein folding and thermodynamically stabilizing the native conformation. We also develop a quantitative method to select appropriate crystal structure resolution and B-factor cutoffs. Detailed knowledge of these geometric and sequence dependences should aid de novo design and prediction algorithms. PMID:21287621

Donald, Jason E.; Kulp, Daniel W.; DeGrado, William F.

2010-01-01

443

Photovoltaic converters for solar-pumped lasers  

NASA Technical Reports Server (NTRS)

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

Walker, Gilbert H.; Heinbockel, John H.

1988-01-01

444

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

Microsoft Academic Search

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

Scott Matthew Kleinmann

2012-01-01

445

Network Bridging Potential in Later Life  

PubMed Central

Objectives Much work in social gerontology has examined older adults’ social connectedness, but we know little about the extent to which older adults occupy positions of power and independence in their networks. The author uses health and life-course frameworks to understand older adults’ prospects of occupying bridging positions between otherwise unconnected individuals. Methods Egocentric social network data were collected from a nationally representative sample of 3,005 older adults between the ages of 57 and 85 in 2005–2006. A series of multivariate regression analyses was used to examine how health and life-course factors relate to bridging. Results Age is not significantly associated with bridging. However, retirees and people with poor health are less likely to have bridging potential. At the same time, widows are more likely to serve as bridges. Discussion The discusses the need for more dialogue between social network researchers and social gerontologists to help explain older adults’ bridging prospects. PMID:19144972

Cornwell, Benjamin

2009-01-01

446

A comparison of bridging fault simulation methods  

Microsoft Academic Search

This study provides bridging fault simulation data obtained from the AMD-K6 microprocessor. It shows that: (1) high stuck-at fault coverage (99.5%) implies high bridging fault coverage; (2) coverage of a bridging fault by both wired-AND and wired-OR behavior does not guarantee detection of that fault when compared against a more accurate (transistor-level simulation) modeling method. A set of netname pairs

R. Scott Fetherston; Imtiaz P. Shaik; Siyad C. Ma

1999-01-01

447

WORLD WISE'99-Winnipeg, Manitoba Taylor Bridge -A Bridge For the 21st  

E-print Network

and build the Taylor "smart" Bridge utilizing fibre reinforced polymer (FRP) reinforcing materials, is considered to be the world's longest highway bridge with girders prestressed with FRP reinforcements and FRP

448

Finding bridges in packings of colloidal spheres  

E-print Network

We identify putative load-bearing structures (bridges) in experimental colloidal systems studied by confocal microscopy. Bridges are co-operative structures that have been used to explain stability and inhomogeneous force transmission in simulated granular packings with a range of densities. We show that bridges similar to those found in granular simulations are present in real experimental colloidal packings. We describe critically the bridge-finding procedure for real experimental data and propose a new criterion-Lowest Mean Squared Separation (LSQS)-for selecting optimum stabilisations.

Matthew C. Jenkins; Mark D. Haw; Gary C. Barker; Wilson C. K. Poon; Stefan U. Egelhaaf

2010-06-17

449

Microcomputer control of power converters  

SciTech Connect

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

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

1984-08-01

450

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

451

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

452

9. VIEW OF BRIDGE NEAR CENTER SPAN, LOOKING NORTH FROM ...  

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

9. VIEW OF BRIDGE NEAR CENTER SPAN, LOOKING NORTH FROM THE ARROYO SECO. THE PARKER-MAYBERRY BRIDGE IS BELOW THE COLORADO STREET BRIDGE, THE PIONEER BRIDGE IS IN THE BACKGROUND. - Colorado Street Bridge, Spanning Arroyo Seco at Colorado Boulevard, Pasadena, Los Angeles County, CA

453

3. CONTEXTUAL VIEW OF BRIDGE IN SETTING, LOOKING SOUTHWEST FROM ...  

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

3. CONTEXTUAL VIEW OF BRIDGE IN SETTING, LOOKING SOUTHWEST FROM ELEVATED GRADE OF EUREKA SOUTHERN RAILROAD. EUREKA SOUTHERN TRUSS BRIDGE AT EXTREME LEFT, 1924 HIGHWAY BRIDGE IN CENTER, 1952 HIGHWAY BRIDGE AT RIGHT - Van Duzen River Bridge, Spanning Van Duzen River at CA State Highway 101, Alton, Humboldt County, CA

454

Bridge Fault Simulation Strategies for CMOS Integrated Circuits Brian Chess  

E-print Network

circuit. The bridge fault transforms the two gates for which the bridged wires are outputs into a singleBridge Fault Simulation Strategies for CMOS Integrated Circuits Brian Chess Tracy Larrabee \\Lambda present a theorem for detecting feedback bridge faults. We discuss two different methods of bridge fault

Larrabee, Tracy

455

MULTI-HAZARD RESISTANT HIGHWAY BRIDGE PIERS HAVING  

E-print Network

of California to its main suspension bridges and the detailed shots of the Golden Gate and Brooklyn bridgesMULTI-HAZARD RESISTANT HIGHWAY BRIDGE PIERS HAVING CONCRETE-FILLED STEEL TUBE Shuichi FUJIKURA1 of a multi-hazard bridge pier concept, i.e., a bridge pier system capable of providing an adequate level

Bruneau, Michel

456

STUDENT STEEL BRIDGE COMPETITION The mission of the Student Steel Bridge Competition (SSBC) is to supplement  

E-print Network

) Co-sponsors are American Iron and Steel Institute (AISI) Bentley Systems, Inc. Canadian Institute but are considered formal addenda to the Rules. #12;4 Section 1 INTRODUCTION Students design and erect a steel bridge1 STUDENT STEEL BRIDGE COMPETITION 2012 RULES #12;2 MISSION The mission of the Student Steel Bridge

Duchowski, Andrew T.

457

Life-Cycle Cost Survey of Concrete Bridge Decks- A Benchmark for FRP Bridge Deck Replacement  

Microsoft Academic Search

A study on the life-cycle cost and performance of concrete bridge decks was conducted to establish a benchmark for fiber-reinforced polymer (FRP) bridge decks. A survey was developed and distributed to State Departments of Transportation engineers and the responses were analyzed. The survey facilitated identifying and estimating the cost parameters associated to concrete bridge deck replacement, and correlating cost with

Roberto Lopez-Anido

2001-01-01

458

Bridge afflux analysis through arched bridge constrictions using artificial intelligence methods  

Microsoft Academic Search

Although many studies have been carried out for estimating the afflux through modern straight deck bridge constrictions, little attention has been given to medieval arched bridge constrictions. Hydraulic Research Wallingford in the UK (Brown, P.M., 1988. Afflux at arch bridges. Report SR 182. Wallingford, UK: HR Wallingford) recently published a major coverage of both experimental and field afflux data obtained

Mustafa Mamak; Galip Seckin; Murat Cobaner; Ozgur Kisi

2009-01-01

459

Capacitance bridge measurements of magnetostriction  

NASA Astrophysics Data System (ADS)

Magnetostriction effects were investigated for three different materials by using a simple, reproducible, and cost-effective method recently developed in our laboratory. The magnetostriction effects were generated by a large oscillating magnetic field produced by a high current 60 Hz ac welder power supply, capable of reaching saturation levels for the material, and then detected by a change in capacitance between a hollow cylindrical sample and a concentric brass ring. This capacitance change was continuously monitored at a high frequency rate by a standard laboratory capacitance bridge meter. The output voltage of the bridge was fed into a storage cathode-ray oscilloscope and its voltage versus time signals were then analyzed by a computer program. Two ferromagnetic rings, constructed of high-speed steels 4620 and 4340, which have proven applicability for use in magnetoelastic torque sensing, were used as the samples for investigating the magnetostriction effects, while a paramagnetic aluminum ring was used for the control sample. Our study showed that the 4340 ring, which had higher nickel, cobalt, and chromium content than that of the 4620 ring, had the largest magnetostriction effect, and that the aluminum ring displayed no magnetostriction effect, as was expected. We have found this experimental method to be both reproducible and sufficient to rank different ferromagnetic materials by their magnetostriction level, which is a significant consideration in producing effective magnetoelastic torque sensors.

Boley, Mark S.; Shin, Won C.; Rigsbee, David K.; Franklin, Doug A.

2002-05-01

460

Salt-Bridge Energetics in Halophilic Proteins  

PubMed Central

Halophilic proteins have greater abundance of acidic over basic and very low bulky hydrophobic residues. Classical electrostatic stabilization was suggested as the key determinant for halophilic adaptation of protein. However, contribution of specific electrostatic interactions (i.e. salt-bridges) to overall stability of halophilic proteins is yet to be understood. To understand this, we use Adaptive-Poison-Boltzmann-Solver Methods along with our home-built automation to workout net as well as associated component energy terms such as desolvation energy, bridge energy and background energy for 275 salt-bridges from 20 extremely halophilic proteins. We then perform extensive statistical analysis on general and energetic attributes on these salt-bridges. On average, 8 salt-bridges per 150 residues protein were observed which is almost twice than earlier report. Overall contributions of salt-bridges are ?3.0 kcal mol?1. Majority (78%) of salt-bridges in our dataset are stable and conserved in nature. Although, average contributions of component energy terms are equal, their individual details vary greatly from one another indicating their sensitivity to local micro-environment. Notably, 35% of salt-bridges in our database are buried and stable. Greater desolvation penalty of these buried salt-bridges are counteracted by stable network salt-bridges apart from favorable equal contributions of bridge and background terms. Recruitment of extensive network salt-bridges (46%) with a net contribution of ?5.0 kcal mol?1 per salt-bridge, seems to be a halophilic design wherein favorable average contribution of background term (?10 kcal mol?1) exceeds than that of bridge term (?7 kcal mol?1). Interiors of proteins from halophiles are seen to possess relatively higher abundance of charge and polar side chains than that of mesophiles which seems to be satisfied by cooperative network salt-bridges. Overall, our theoretical analyses provide insight into halophilic signature in its specific electrostatic interactions which we hope would help in protein engineering and bioinformatics studies. PMID:24743799

Nayek, Arnab; Sen Gupta, Parth Sarthi; Banerjee, Shyamashree; Mondal, Buddhadev; Bandyopadhyay, Amal K.

2014-01-01

461

Thermionic converter studies at Thermo Electron  

NASA Technical Reports Server (NTRS)

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

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

1977-01-01

462

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

463

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

464

Heat flow in a pyroelectric converter  

NASA Astrophysics Data System (ADS)

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

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

1985-12-01

465

Gadolinium sheet converter for neutron radiography.  

PubMed

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

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

2007-12-01

466

Simplified Heat-Source/Thermionic Converter  

NASA Technical Reports Server (NTRS)

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

Shimada, K.

1983-01-01

467

Integral abutment bridge response under thermal loading  

Microsoft Academic Search

This paper presents a parametric study and approximate integral abutment bridge (IAB) response prediction models. IABs are complex structures due to the nonlinearity and uncertainties in bridge materials and soil boundaries. Current design specifications and guides do not provide clearly defined analysis methods; therefore, there is a need for easily implemented preliminary analysis and accurate two-dimensional (2D) analysis methods. Based

WooSeok Kim; Jeffrey A. Laman

2010-01-01

468

Small Schools: Bridging the Need for Community  

ERIC Educational Resources Information Center

This article describes the experience of teaching in a small school in New York City. It is observed that this offers opportunities for individuals to grow independently and to understand their impact on community and society. As they bridge the gap between becoming a teacher and understanding how to build bridges for children that are moving…

Hamilton, Greg

2005-01-01

469

Balsa Wood Bridge Competition Sponsored by  

E-print Network

capable of supporting a given load over a given span. The bridge must allow the passage of one Hot Wheel surface of the test supports. � The road surface is defined as the surface that will allow a Hot Wheel Car high wooden block. The Hot Wheel's car will be placed on the elevated portion of the bridge

Wang, Xiaorui "Ray"

470

Balsa Wood Bridge Competition Sponsored by  

E-print Network

capable of supporting a given load over a given span. The bridge must allow the passage of one Hot Wheel. · The road surface is defined as the surface that will allow a Hot Wheel Car to pass the length. However block. The Hot Wheel's car will be placed on the elevated portion of the bridge and will be allowed

Tennessee, University of

471

BEHAVIOUR OF BRIDGE DECKS REINFORCED BY GFRP  

E-print Network

-scale highway bridge deck model reinforced by glass fibre reinforced polymer (GFRP) reinforcements and tested of the reinforcement ratio and type of reinforcement on the behaviour ofbridge decks are presented. KEYWORDS: bridge structures subjected to aggressive environmental conditions is attributed to the corrosion of the steel

472

Bridges to Healthy Communities. AACC Project Brief.  

ERIC Educational Resources Information Center

The Bridges to Healthy Communities project assists community colleges in offering education and information services that help prevent HIV infection and other serious health problems in students. The five-year Bridges project emphasizes service learning as a community-building and intervention strategy for preventing HIV infection. This initiative…

Ottenritter, Nan; Barnett, Lynn

473

RELIABILITY ANALYSIS OF SUSPENSION BRIDGES AGAINST FLUTTER  

Microsoft Academic Search

A reliability analysis of suspension bridges against flutter failure is presented using the basic theory of reliability. For the purpose of analysis, uncertainties considered are those arising from the variations in geometric and mechanical properties of bridge, modelling, damping and experimentally obtained flutter derivatives. These uncertainties are incorporated by multiplying the computed flutter wind speed with a number of independent

S. Pourzeynali; T. K. DATTA

2002-01-01

474

Build and Test a Paper Bridge  

NSDL National Science Digital Library

In this hands-on activity, learners make a bridge out of a folded piece of paper and two blocks. Then they test their structure by stacking coins (and other things) on it, discovering how much weight the bridge can support before it collapses. This activity explores engineering, technology, architecture, weight, compression, tension, and balance.

Science, New Y.

1999-01-01

475

Bridges and the City: An Interdisciplinary Project.  

ERIC Educational Resources Information Center

Describes an interdisciplinary project to help elementary school children discover the relationship among technology, history, and geography that involved the building of a model Brooklyn Bridge and considering the history and role of the real bridge. Suggestions for similar projects for other cities are appended. (JPB)

Singer, Judith Y.; Goodman, Cecelia; Ridley, Theodora; Singer, Alan

2000-01-01

476

Simple Bridge for Pulsed Nuclear Magnetic Resonance  

Microsoft Academic Search

An asymmetrical rf bridge for pulsed magnetic resonance experiments is described. The balancing adjustments, which can be made quickly and easily, ensure a proper impedance match to transmitter and receiver. The bridge is particularly well suited for pure nuclear quadrupole resonance experiments.

K. R. Jeffrey; R. L. Armstrong

1967-01-01

477

Recent Innovation for Concrete Highway Bridges  

E-print Network

, Calgary, Alberta) is prestressed by carbon fiber reinforced plastic (CFRP) tendons and instrumented in Manitoba using straight and draped CFRP tendons for prestressing the girder, CFRP stirrups for shear reinforcement. CFRP for flexural reinforcement of the deck slab and GFRP for the bridge curbs. All bridges

478

THE BRIDGE COUPLING CAVITIES IN THE SEPARATED  

Microsoft Academic Search

The Separated Drift Tube Linac (SDTL) structure was pro- posed for medium energy range of proton linacs. The ac- celerating cavity consists of several SDTL units with fo- cusing lenses between sections. To drive several SDTL sections from single RF source, application of both RF power dividers and coupling bridge cavities seems feasible. Through bridge couplers, the field distribution, in

V. V. Paramonov; L. V. Kravchuk; A. S. Levchenko

479

BDES: A bridge design expert system  

Microsoft Academic Search

The expert system described here designs superstructures for small to medium span highway bridges. The system addresses a domain within the engineering design consultation paradigm. It is installed in a personal microcomputer environment. This paper examines the nature of the bridge design domain as practiced in the United States and its suitability for expert system application. The architecture, the context

Mrinmay Biswas; James G. Welch

1987-01-01

480

Teaching Elements and Principles of Bridge Design  

ERIC Educational Resources Information Center

Bridge construction is a popular classroom activity. However, the basic principles of tension, compression, and counterbalance are not always clearly represented and defined. The common materials used to construct model bridges, such as straws, toothpicks, Legos[TM], and building blocks, are often too flexible or stationary to demonstrate the…

Beck, Charles

2005-01-01

481

A bridging model for parallel computation  

Microsoft Academic Search

The success of the von Neumann model of sequential computation is attributable to the fact that it is an efficient bridge between software and hardware: high-level languages can be efficiently compiled on to this model; yet it can be effeciently implemented in hardware. The author argues that an analogous bridge between software and hardware in required for parallel computation if

Leslie G. Valiant

1990-01-01

482

Resiliency of Bridges on the BOSFOLK Corridor.  

National Technical Information Service (NTIS)

Built with a design life of 50-years, many of the bridges on the Boston to Norfolk (BOSFOLK) corridor are nearing the end of their design life. Neglect, poor maintenance, and insufficient funding have left many of them in very bad condition. As the bridge...

H. W. Shenton, P. Seymour

2013-01-01

483

The adventures of the bridge jumper  

Microsoft Academic Search

Steve Brodie's 1886 jump from the Brooklyn Bridge created a particularly modern fame that has much to tell us about the emergence of modern media celebrity and the kinds of spectacular stunt performances that could be mobilised to create it in the years just before the cinema. Bridge jumpers such as Brodie took the modern urban landscape as their backdrop,

Jacob Smith

2010-01-01

484

On configurable oversampled A/D converters  

SciTech Connect

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

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

1993-07-01

485

DC/DC Converter Stability Testing Study  

NASA Technical Reports Server (NTRS)

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

Wang, Bright L.

2008-01-01

486

1. Contextual view of bridge in setting, from downstream, view ...  

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

1. Contextual view of bridge in setting, from downstream, view to southwest along Port Kenyon Road. South end of bridge at left. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

487

27. View of underside of ninth bridge, showing concrete mixture, ...  

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

27. View of underside of ninth bridge, showing concrete mixture, view to the NW. - Vicksburg National Military Park Roads & Bridges, Melan Arch Bridges, Spanning various tributaries at Confederate Avenue, Vicksburg, Warren County, MS

488

15. View of Tombigbee River Bridge facing same direction as ...  

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

15. View of Tombigbee River Bridge facing same direction as in photograph no. MS-13-14 except this view is the underside of the bridge. - Tombigbee River Bridge, Spanning Tombigbee River at State Highway 182, Columbus, Lowndes County, MS

489

7. View of Tombigbee River Bridge facing just right on ...  

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

7. View of Tombigbee River Bridge facing just right on view shown in photograph no. MS-13-G. New bridge is partially shown in the background. - Tombigbee River Bridge, Spanning Tombigbee River at State Highway 182, Columbus, Lowndes County, MS

490

13. Fourth Melan Bridge on tour route, Union Avenue near ...  

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

13. Fourth Melan Bridge on tour route, Union Avenue near bust of General John Thayer, elevation detail view to the north. - Vicksburg National Military Park Roads & Bridges, Melan Arch Bridges, Spanning various tributaries at Confederate Avenue, Vicksburg, Warren County, MS

491

STEEL ERECTION. View of upstream side of bridge, looking north ...  

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

STEEL ERECTION. View of upstream side of bridge, looking north from the old suspension bridge at unjoined cantilever arms - South Fork Trinity River Bridge, State Highway 299 spanning South Fork Trinity River, Salyer, Trinity County, CA

492

Aeroelastic Analysis of Bridges: Effects of Turbulence and Aerodynamic Nonlinearities  

E-print Network

by utilizing an example of a long span suspension bridge with aerodynamic characteristics sensitiveAeroelastic Analysis of Bridges: Effects of Turbulence and Aerodynamic Nonlinearities Xinzhong Chen for capturing the emerging concerns in bridge aerodynamics introduced by aerodynamic nonlinearities

Kareem, Ahsan

493

9. View of bridge looking west. A fundraising marathon is ...  

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

9. View of bridge looking west. A fund-raising marathon is in prgress. The traffic levels outside the main arch were added in 1965 when the bridge underwent extensive rehabilitation. - Detroit Superior High Level Bridge, Cleveland, Cuyahoga County, OH

494

2. Contextual view of bridge in setting, from north end ...  

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

2. Contextual view of bridge in setting, from north end of bridge, view to north along Dillon Road. Former Valley Flower Creamery at right center. - Salt River Bridge, Spanning Salt River at Dillon Road, Ferndale, Humboldt County, CA

495

1. Photocopy from George S. Morison's The Plattsmouth Bridge, 1882. ...  

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

1. Photocopy from George S. Morison's The Plattsmouth Bridge, 1882. Photographer unknown, circa 1880. SOUTH WEB AND WEST PORTAL OF BRIDGE - Plattsmouth Bridge, Spanning Missouri River, Plattsmouth, Cass County, NE

496

1. Photocopy from George S. Morison's The Sioux City Bridge, ...  

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

1. Photocopy from George S. Morison's The Sioux City Bridge, 1890. Photographer unknown, circa 1889. SOUTH WEB AND WEST PORTAL OF BRIDGE - Sioux City Bridge, Spanning the Missouri River, Sioux City, Woodbury County, IA

497

1. Photocopy from George S. Morison's The Blair Crossing Bridge, ...  

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

1. Photocopy from George S. Morison's The Blair Crossing Bridge, 1886. Photographer unknown, circa 1883. SOUTH WEB AND WEST PORTAL OF BRIDGE - Blair Crossing Bridge, Spanning Missouri River, Blair, Washington County, NE

498

General perspective view of the North Fork Butter Creek Bridge, ...  

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

General perspective view of the North Fork Butter Creek Bridge, view looking north - North Fork Butter Creek Bridge, Spanning North Fork Butter Creek Bridge at Milepost 76.63 on Heppner Highway (Oregon Route 74), Pilot Rock, Umatilla County, OR

499

Approach view of the North Fork Butter Creek Bridge, view ...  

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

Approach view of the North Fork Butter Creek Bridge, view looking north - North Fork Butter Creek Bridge, Spanning North Fork Butter Creek Bridge at Milepost 76.63 on Heppner Highway (Oregon Route 74), Pilot Rock, Umatilla County, OR

500

Elevation view of the North Fork Butter Creek Bridge, view ...  

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

Elevation view of the North Fork Butter Creek Bridge, view looking west - North Fork Butter Creek Bridge, Spanning North Fork Butter Creek Bridge at Milepost 76.63 on Heppner Highway (Oregon Route 74), Pilot Rock, Umatilla County, OR