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1

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

SciTech Connect

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

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

2010-08-15

2

Power factor correction with flyback converter employing charge control  

Microsoft Academic Search

The charge control concept is applied to a flyback power converter for the purpose of power factor correction (PFC). Using charge control, a flyback converter can operate in continuous conduction-mode (CCM) with unity power factor. The simplicity of the flyback circuit is maintained and the power handling capacity is increased. The properties of charge control related to flyback PFC application

W. Tang; Y. Jiang; G. C. Hua; F. C. Lee; I. Cohen

1993-01-01

3

Zero voltage switching approach for flyback converter  

Microsoft Academic Search

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

K. Yoshida; T. Ishii; N. Nagagata

1992-01-01

4

An integrated flyback converter for DC uninterruptible power supply  

Microsoft Academic Search

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

Kwok-Wai Ma; Yim-Shu Lee

1996-01-01

5

An integrated flyback converter for DC uninterruptible power supply  

Microsoft Academic Search

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

Kwok-Wai Ma; Yim-Shu Lee

1994-01-01

6

A novel active clamped dual switch flyback converter  

Microsoft Academic Search

In this paper, A novel ZVZCS active clamped dual switch flyback converter was proposed, whose main switches and auxiliary switch all realize zero-voltage turning-on, and the rectifier diode on the secondary side also achieves ZCS. It overcomes the demerit of high voltage stress on the main switch in conventional flyback converter; meanwhile the duty circle can extend to more than

Ping Rong; Wei Chen; Zhengyu Lu

2009-01-01

7

An integrated flyback converter for DC uninterruptible power supply  

SciTech Connect

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

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

1996-03-01

8

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

9

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

Microsoft Academic Search

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

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

2007-01-01

10

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

Microsoft Academic Search

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

Murat Seker; Erkan Zergeroglu

2011-01-01

11

Series resonant converter using flyback control  

NASA Astrophysics Data System (ADS)

Series resonant converters are widely used in applications requiring high power density. They offer several advantages over other topologies such as simplicity of design, switching at zero current levels, and high efficiency due to low switching losses. A new converter will be proposed that delivers pulses of equal energy to the load with comparatively small pulse-to-pulse delay and draws sinusoidal input current pulses. Also, the conventional charge and discharge cycle of the commutation capacitor is eliminated. The capacitor voltage is bidirectional and energy is transferred from the capacitor to the load during each switching cycle. This topology does not generate any abruptly discontinuous current waveforms, therefore, the EMI produced is minimal.

Lee, H. T.; Josephs, L. C.

12

Active Clamp Interleaved Flyback Converter with Single-Capacitor Turn-off Snubber for Stunning Poultry Applications  

Microsoft Academic Search

The paper proposes an active clamp interleaved flyback converter with a single-capacitor turn-off snubber associated with a full-bridge inverter for stunning poultry applications. The proposed converter can use active clamp circuit to recover the energy of transformer and to achieve zero-voltage switching at turn-on transition. In addition, the proposed one adopts a single-capacitor snubber not only to smooth out switch

S.-Y. Tseng; C.-T. Hsieh; H.-C. Lin

2007-01-01

13

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

14

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

Microsoft Academic Search

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

B. Singh; G. D. Chaturvedi

2008-01-01

15

Design of a 28 V-to-300 V\\/12 kW Multicell Interleaved Flyback Converter Using Intercell Transformers  

Microsoft Academic Search

A low-input voltage high-power realization is presented with the aim to demonstrate the feasibility and the interest of topologies using intercell transformer. They constitute a promising option to interleave converter stages, and therefore, can answer to the specifications considered in this paper. These specifications require a galvanic insulation and the chosen topology is the Intercell Transformer (ICT) flyback converter, previously

François Forest; Bertrand Gelis; Jean-Jacques Huselstein; Bernardo Cougo; Eric Laboure; Thierry Meynard

2010-01-01

16

Coupled Input-Series and Output-Parallel Dual Interleaved Flyback Converter for High Input Voltage Application  

Microsoft Academic Search

This paper proposes an integrated magnetic dc-dc converter suitable for high input voltage application. The converter is based on a coupled input-series and output-parallel dual interleaved Flyback converter concept. All the center and outer legs are gapped, and the transformers are integrated into one magnetic core with not so tight coupling. The gap is beneficial for suppressing current spike caused

Ting Qian; Brad Lehman

2008-01-01

17

Cascaded resonant bridge converters  

NASA Technical Reports Server (NTRS)

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

Stuart, Thomas A. (Inventor)

1989-01-01

18

An approach to achieve ride-through of an adjustable-speed drive with flyback converter modules powered by super capacitors  

Microsoft Academic Search

Adjustable-speed drives under short-term power interruptions can interrupt a critical process. In this paper, an approach to provide ride-through with flyback converter modules powered by super capacitors is explored. The proposed approach is modular and facilitates additional modules to be added to suit higher voltage\\/power ratings. Both unidirectional and bidirectional flyback DC\\/DC converter topologies are examined. Simulation and experimental results

José Luis Durán-Gómez; Prasad N. Enjeti; Annette von Jouanne

2002-01-01

19

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

20

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

21

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

Microsoft Academic Search

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

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

2010-01-01

22

Design of boost-flyback converter with small capacitor for energy-storage  

Microsoft Academic Search

This paper presents the idea of utilizing large voltage ripple with small capacitance for energy storage in LED circuit, instead of large capacitance with small voltage ripple. A typical Single-Stage PFC converter with small capacitor is adopted. The presented converter has high input power factor and low output voltage ripple at the same time. Calculation method of main parameters are

Xuejun Ma; Xiumei Yue

2010-01-01

23

A Study on Optimization of the Wireless Power Transfer Using the Half-Bridge Flyback Converter  

Microsoft Academic Search

We considered about a wireless power transfer for breaking inconvenience of wiring power sources. The best way how to supply electric power through wireless system is using the electromagnetic coupled resonance phenomena. It can be supplied the electric power to the load. It is analyzed the transfer characteristics through the basic experiment with variable LED load. And we could apply

Jin-Ju Jang; Won-Yong Chae; Ho-Sung Kim; Dong-Gil Lee; Hee-Je Kim

2010-01-01

24

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

25

A novel soft-switching full-bridge converter  

Microsoft Academic Search

Inserting an auxiliary switch to the conventional hard-switch full-bridge topology, a novel soft-switching full-bridge converter is proposed. Instead of the main switches, the auxiliary switch is pulse-width modulated to regulate the output voltage and soft-switching operation of the main switches can be easily achieved over full line and load ranges. Consequently, the reduced switching losses can be compensated for the

Chia-Wei Lee; Ching-Shan Leu

2009-01-01

26

DC power supply based on half bridge LCC resonant converter  

Microsoft Academic Search

Design of DC power supply using half bridge LCC series-parallel resonant converter is proposed in this paper. The DC power supply input voltage is DC 24 V and output voltage is DC 3.3 V. The voltage regulation using variable frequency control is investigated for 3.3 V under different load condition. The performance of the system is first simulated by IsSpice.

Chin-Hsing Cheng; Yao-Chou Lee

2009-01-01

27

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

Microsoft Academic Search

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

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

1999-01-01

28

DC bus ripple minimization in cascaded H-bridge multilevel converters under staircase modulation  

Microsoft Academic Search

Cascade connected H bridge multilevel converters are becoming an attractive topology for very high power applications. Due the single phase loading of the individual bridges, the DC link capacitors required in these converters are faced with a heavy stress. The problem is particularly acute with stair-case type modulation strategies. This paper presents an approach for equalizing the power drawn from

Yusuke Fukuta; Giri Venkataramanan

2002-01-01

29

Furai Bakku Busuta (Fly-Back Boosters).  

National Technical Information Service (NTIS)

The first system review on rocket systems composed of fly-back booster and expendable upper-stage rockets which are capable of launching a payload of 30 tons into low earth orbit is conducted. Three types of winged reusable fly-back booster systems are re...

T. Makino S. Matsuda

1991-01-01

30

Tri-Modal Half-Bridge Converter Topology for Three-Port Interface  

Microsoft Academic Search

This letter proposes a novel converter topology that interfaces three power ports: a source, a bidirectional storage port, and an isolated load port. The proposed converter is based on a modified version of the isolated half-bridge converter topology that utilizes three basic modes of operation within a constant-frequency switching cycle to provide two independent control variables. This allows tight control

Hussam Al-Atrash; Feng Tian; Issa Batarseh

2007-01-01

31

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

32

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

33

Constant frequency controlled full-bridge LCC-type parallel resonant converter  

Microsoft Academic Search

A constant-frequency controlled full-bridge LCC-type parallel resonant converter is presented. By using a proper transformation on the state variables, the converter is analyzed by means of a two-dimensional state-plane diagram, which shows that the converter possesses three operation modes. Control characteristics and component stress curves are derived for only operation mode II. It is shown that operating that converter in

C. Q. Lee; S. Sooksatra; R. Liu

1991-01-01

34

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

35

A soft-switched, full-bridge boost converter employing an active-clamp circuit  

Microsoft Academic Search

A new full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation. The active-clamp network serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching. PWM phase-shift control of the bridge switches is utilized to obtain zero-current switching for

R. Watson; F. C. Lee

1996-01-01

36

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

37

Analysis of a full-bridge LCC-type parallel resonant converter with capacitive output filter  

Microsoft Academic Search

The purpose of this paper is to study the performance of a full-bridge three element LCC resonant power converter with a capacitive output filter. The study focuses on the operation under pulsewidth modulation with variable operation frequency. The operation modes of the LCC power converter are evaluated and their boundaries are given by means of normalised diagrams. Furthermore, optimal operation

C. Loef

1997-01-01

38

A simple firing delay control circuit for bridge converters  

Microsoft Academic Search

A simple ramp control firing circuit, suitable for use with fully controlled, line-commutated thyristor bridge circuits, is discussed here. This circuit uses very few components and generates the synchronized firing pulses in a simple way. It operates from a single 15 V Supply and has an inherent pulse inhibit facility. This circuit provides the synchronized firing pulses for both thyristors of

SUJIT KUMAR BISWAS

1982-01-01

39

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

40

A high-reliability, low-cost, interleaved bridge converter  

Microsoft Academic Search

The interleaved bridge topology uses two transformers in series to act as both inductor and transformer, allowing zero-voltage resonant transition switching for high-frequency, low-loss operation. High frequency reduces the requirement for large filter capacitors and reduces the size of the magnetics. Costs are reduced by trading electrolytic capacitors for ceramic capacitors, which also improves reliability. Costs are also reduced by

Joseph H. Mulkern; Christopher P. Henze; David S. Lo

1991-01-01

41

Flyback Versus Forward Switching Power Supply Topologies For Unipolar Pulsed-Power Applications  

Microsoft Academic Search

We discuss and compare modified flyback and forward switching power converter topologies in applications needing repetitive high-voltage (HV) low duty-cycle rectangular unipolar pulses. The output filters of these two converter topologies are removed, and the needed low duty-cycle operation is used advantageously to generate several kilovolts of pulses using only low-voltage seriesless semiconductors. The two circuits proposed are based on

L. M. Redondo; J. Fernando Silva

2009-01-01

42

Current Sharing Analysis of Arm Prototype for ITER PF Converter Bridge  

NASA Astrophysics Data System (ADS)

A bridge arm prototype of ITER poloidal field (PF) converter modules has been designed and fabricated. Non-cophase counter parallel connection is chosen as the arm structure of the prototype. Among all factors affecting current sharing, arm structure is the main one. During the design of the arm prototype, a novel method based on inductance matrixes is employed to improve the current sharing of the bridge arm. The test results on the prototype show that the current sharing performance of the arm prototype is much better than relevant design requirement, and that the matrix method is very effective to analyze and solve the current sharing problems of thyristor converters.

Li, Jinchao; Song, Zhiquan; Xu, Liuwei; Fu, Peng; Guo, Bin; Li, Sen; Dong, Lin; Wang, Min

2014-03-01

43

Stress analysis of a full bridge ZVS DC-DC converter  

Microsoft Academic Search

This paper presents the MOSFET electrical stresses in a full bridge (FB) ZVS DC-DC converter with a detailed study of the MOSFET body diode reverse recovery stress under normal and low load operating conditions. Experimental results are presented under normal and low load operation for a 350 V-3.5 V, 225 A FB ZVS DC-DC converter. Two-dimensional (2-D) numerical simulation results

S. Abedinpour; R. Burra; K. Shenai

2001-01-01

44

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

Microsoft Academic Search

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

Francois Guerin; Cecile Labarre; Dimitri Lefebvre

2011-01-01

45

Common-mode noise source and its passive cancellation in full-bridge resonant converter  

Microsoft Academic Search

In this paper the results of systematic investigation into identification of dominant source of CM noise generation in a full bridge resonant converter are presented. It is shown that a small mismatch in an apparently symmetrical circuit can result in large CM injection. Mathematical analysis to predict the CM current injection is presented and is validated using SPICE simulation. For

Mangesh Borage; Sunil Tiwari; S. Kotaiah

2003-01-01

46

Simplified input current waveshaping technique by using inductor voltage sensing for high power factor isolated Sepic, Cuk and flyback rectifiers  

Microsoft Academic Search

This paper, a new simple current waveshaping technique in CCM by using inductor voltage sensing for high power factor rectifier based on isolated Sepic, Cuk, and flyback converters is introduced and experimented. The duty ratio is obtained by comparing an integral signal of the rectified inductor voltage and a negative ramp carrier waveform. Using the proposed control technique, input voltage

T. Tanitteerapan; S. Mori

2002-01-01

47

Sliding mode control design of current fed full bridge DC to DC converter for fuel cell applications  

Microsoft Academic Search

Since a fuel cell system has a low voltage output, it requires a boost DC\\/DC converter for the most of vehicle and stationary power applications. In this paper, a robust sliding mode controller for the current fed full bridge DC\\/DC converter for PEM fuel cell systems is presented. The details of the sliding mode controller for the converter are derived

Woonki Na; Hoon Lee

2011-01-01

48

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

49

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

50

PWM and phase-shifted control method for isolated asymmetric half- bridge bi-directional converter  

Microsoft Academic Search

In this paper, a novel improved control method for Isolated asymmetric half bridge (IAHB) bi-directional converter (BDC) is proposed. Usually traditional phase-shift(PS) control method is applied in the topology. Theory analysis and simulation results show there are a big current press more than ration current and the loss will be greater under the case that the voltage of low voltage

Xuejun Ma; HongXia Wu; Xiumei Yue

2008-01-01

51

Novel half-bridge resonant converter topology realized by adjusting transformer parameters  

Microsoft Academic Search

This paper shows a new direction as to how the transformer parameters may be best utilized and presents the performance and control of novel DC\\/DC and AC\\/DC converter topologies. All three inductances of a transformer have been utilized to realize a CL3 topology having excellent characteristics and requiring no external inductor. For the half-bridge topology, the capacitor used for the

Chandan Chakraborty; Muneaki Ishida; Yoichi Hori

2002-01-01

52

Analysis and design of a saturable reactor assisted soft-switching full-bridge dc-dc converter  

SciTech Connect

Analysis and design considerations for a saturable reactor assisted soft-switching full-bridge dc-dc converter are presented. The converter has advantages such as low switching losses with no substantial increase in conduction losses, wide load range, and constant frequency operation. To show how to utilize the analysis results, a 350-W, 500-kHz converter is chosen as a design example. The results are verified experimentally on a prototype converter.

Hamada, Satoshi (Sansha Electric Manufacturing Co., Ltd., Osaka (Japan)); Nakaoka, Mutsuo (Kobe Univ. (Japan). Dept. of Electrical and Electronics Engineering)

1994-05-01

53

Analysis and Design of High-Frequency Isolated Dual-Bridge Series Resonant DC\\/DC Converter  

Microsoft Academic Search

Bidirectional dual-bridge dc\\/dc converter with high frequency isolation is gaining more attentions in renewable energy system due to small size and high-power density. In this paper, a dual-bridge series resonant dc\\/dc converter is analyzed with two simple modified ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and

Xiaodong Li; Ashoka K. S. Bhat

2010-01-01

54

Ac equivalent circuit analysis for high-frequency isolated dual-bridge series resonant dc\\/dc converter  

Microsoft Academic Search

Bidirectional dual-bridge DC\\/DC converter with high-frequency isolation is gaining more attentions due to small size, high power density. In this paper, a dual-bridge series resonant DC\\/DC converter is analyzed with two simple ac equivalent circuit analysis methods for both voltage source load and resistive load. In both methods, only fundamental components of voltages and currents are considered. All the switches

Xiaodong Li; A. K. S. Bhat

2008-01-01

55

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

56

A Three-phase Dual Active Bridge Bidirectional ZVS DC/DC Converter  

NASA Astrophysics Data System (ADS)

This paper discusses the detailed operations of a three-phase dual active bridge bidirectional zero-voltage switching (ZVS) DC/DC converter (TPDAB) which transfers a bidirectional power flow between a 12 V net and a high voltage DC net. The converter is controlled by phase-shift-modulation (PSM) with a fixed duty cycle D=1/3. It features isolation, smoother drawing and injecting current from the 12 V net, smaller capacitances, smaller switch current stress, ZVS over a wide range, high efficiency and a large power handling capability. The mathematic model is analyzed. The soft-switching principle is described and its ZVS criterias are derived. The simulation and experimental results are provided to verify the theoretical analysis.

Xuan, Zhang; Shenghua, Huang; Guoyun, Ning

57

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

58

Family of Zero-Current Transition PWM Converters  

Microsoft Academic Search

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

Ehsan Adib; Hosein Farzanehfard

2008-01-01

59

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.

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

60

Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.  

PubMed

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; Su, Jye-Chau; Tseng, Sheng-Yu

2013-01-01

61

Some criteria of topology selection for hybrid converters  

Microsoft Academic Search

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

S. Radosevic; M. Lazic; R. Ramovic

1997-01-01

62

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

63

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

Microsoft Academic Search

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

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

2006-01-01

64

Open-Circuit Fault Diagnosis and Fault-Tolerant Strategies for Full-Bridge DC–DC Converters  

Microsoft Academic Search

This paper proposes a four-step open-circuit fault diagnosis and fault-tolerant scheme for isolated phase-shifted full-bridge (PSFB) dc–dc converters to improve the reliability. The fault diagnostic method utilizes the primary voltage of the transformer as the diagnostic criterion, which can be obtained easily by adding an auxiliary winding. When an open-circuit fault occurs in any switch of the PSFB converter, the

Xuejun Pei; Songsong Nie; Yu Chen; Yong Kang

2012-01-01

65

An improved full bridge zero-voltage switching PWM DC-DC converter using a two inductor rectifier  

Microsoft Academic Search

An improved full bridge ZVS (zero-voltage switching) PWM (pulse-width-modulated) converter using a two inductor rectifier DC\\/DC power converter is presented. For this improved topology the main devices are switched on under ZVS conditions using the energy stored in the secondary filter inductors. It utilizes the low leakage inductance of a coaxial winding transformer to reset the currents in the rectifier

N. H. Kutkut; D. M. Divan; R. W. Gascoigne

1993-01-01

66

New Zero Current Transition PWM Converters  

Microsoft Academic Search

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

E. Adib; H. Farzaneh-fard

2006-01-01

67

New Zero Voltage Transition PWM Converters  

Microsoft Academic Search

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

E. Adib; H. Farzaneh-fard

2006-01-01

68

Cardiomyopathy mutations reveal variable region of myosin converter as major element of cross-bridge compliance.  

PubMed

The ability of myosin to generate motile forces is based on elastic distortion of a structural element of the actomyosin complex (cross-bridge) that allows strain to develop before filament sliding. Addressing the question, which part of the actomyosin complex experiences main elastic distortion, we suggested previously that the converter domain might be the most compliant region of the myosin head domain. Here we test this proposal by studying functional effects of naturally occurring missense mutations in the beta-myosin heavy chain, 723Arg --> Gly (R723G) and 736Ile --> Thr (I736T), in comparison to 719Arg --> Trp (R719W). All three mutations are associated with hypertrophic cardiomyopathy and are located in the converter region of the myosin head domain. We determined several mechanical parameters of single skinned slow fibers isolated from Musculus soleus biopsies of hypertrophic cardiomyopathy patients and healthy controls. Major findings of this study for mutation R723G were i), a >40% increase in fiber stiffness in rigor with a 2.9-fold increase in stiffness per myosin head (S( *)(rigor R723G) = 0.84 pN/nm S( *)(rigor WT) = 0.29 pN/nm); and ii), a significant increase in force per head (F( *)(10 degrees C), 1.99 pN vs. 1.49 pN = 1.3-fold increase; F( *)(20 degrees C), 2.56 pN vs. 1.92 pN = 1.3-fold increase) as well as stiffness per head during isometric steady-state contraction (S( *)(active10 degrees C), 0.52 pN/nm vs. 0.28 pN/nm = 1.9-fold increase). Similar changes were found for mutation R719W (2.6-fold increase in S( *)(rigor); 1.8-fold increase in F( *)(10 degrees C), 1.6-fold in F( *)(20 degrees C); twofold increase in S( *)(active10 degrees C)). Changes in active cross-bridge cycling kinetics could not account for the increase in force and active stiffness. For the above estimates the previously determined fraction of mutated myosin in the biopsies was taken into account. Data for wild-type myosin of slow soleus muscle fibers support previous findings that for the slow myosin isoform S( *) and F( *) are significantly lower than for fast myosin e.g., of rabbit psoas muscle. The data indicate that two mutations, R723G and R719W, are associated with an increase in resistance to elastic distortion of the individual mutated myosin heads whereas mutation I736T has essentially no effect. The data strongly support the notion that major elastic distortion occurs within the converter itself. Apparently, the compliance depends on specific residues, e.g., R719 and R723, presumably located at strategic positions near the long alpha-helix of the light chain binding domain. Because amino acids 719 and 723 are nonconserved residues, cross-bridge stiffness may well be specifically tuned for different myosins. PMID:19651039

Seebohm, B; Matinmehr, F; Köhler, J; Francino, A; Navarro-Lopéz, F; Perrot, A; Ozcelik, C; McKenna, W J; Brenner, B; Kraft, T

2009-08-01

69

Bridges  

MedlinePLUS

... This type of bridge is also called a resin-bonded bridge or an acid-etched bridge. Bonded bridges usually ... are only as strong as the bonding material. Resin-bonded bridges tend not to stay cemented in place as ...

70

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

71

Method of controlling switching of a multiphase inductor-converter bridge  

DOEpatents

In an inductor-convertor circuit for transferring electrical energy between a storage coil and a load coil using a storage thyristor bridge, a load thyristor bridge, and a set of commutating capacitors, operation is improved by a method of changing the rate of delivery of energy in a given direction. The change in rate corresponds to a predetermined change in phase angle between the load bridge and the storage bridge and comprises changing the phase of the bridge by two steps, each equal to half the predetermined change and occurring 180.degree. apart. The method assures commutation and minimizes imbalances that lead otherwise to overvoltages.

Kustom, Robert L. (Palos Heights, IL); Fuja, Raymond E. (Justice, IL)

1981-01-01

72

An improved full-bridge zero-voltage switching PWM converter using a two-inductor rectifier  

Microsoft Academic Search

An improved full-bridge ZVS PWM power convertor using a two-inductor rectifier DC\\/DC power converter is presented in this paper. For this improved topology, the main devices are switched under zero-voltage (ZVS) conditions using the energy stored in the secondary filter inductors. In addition, it utilizes the low leakage inductance of a coaxial winding transformer to reset the currents in the

Nasser H. Kutkut; Deepakraj M. Divan; Randal W. Gascoigne

1995-01-01

73

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

74

MOSFET flyback-diode conduction and dV\\/dt effects in power ICs in low-voltage motor control applications  

Microsoft Academic Search

In a power IC, the direct drive of a low-voltage motor by one or more MOSFET half-bridges results in inductive-flyback diode conduction during switching transitions. PISCES computer simulation reveals that this diode current in an integrated lateral MOSFET manifests itself as parasitic bipolar conduction where a substantial fraction of the carriers injected from the forward-biased drain-to-body junction is collected by

Richard K. Williams; Michael E. Cornell; James A. Harnden

1991-01-01

75

Bridges  

NSDL National Science Digital Library

Bridges have been drawing plenty of attention lately, with numerous construction projects around the world and the controversy over the deteriorating bridge infrastructure in the US. They have been an essential part of transportation for hundreds of years, and it is the job of civil engineers to design the safest, most durable bridges possible.Bridge Basics (1) has a large list of different types of bridges with brief explanations. This is a good place for beginners to learn about various bridge designs and parts. The Web site of a nationwide engineering design contest (2) offers free West Point Bridge Designer software. This educational tool allows the user to create a custom virtual bridge model. Although this year's contest is over, another one is planned for next year. Rice University is the home of the Bridges Project (3), a comprehensive database of "all 74 1,000 ft. span bridges in the United States." For each of these, a short description and construction history are given, and some include photos and other interesting facts. The Gibraltar Bridge, a proposed nine mile bridge that connects Europe and Africa, was recently featured on the Discovery Channel's Engineering the Impossible (4). This Web site discusses its specifications, as well as the many challenges that must be overcome for it to be a reality. The Innovative Bridge Research and Construction Program (5) investigates new technologies that can be used in the "repair, rehabilitation, replacement and new construction of bridges" in the US. This is particularly important now, since a large portion of the countries bridges are badly in need of maintenance. A more specific area of research being conducted to protect bridge infrastructure involves the corrosion of steel reinforcements in concrete bridges (6). The material on this site provides an in-depth report on the findings of the Turner-Fairbank Highway Research Center. Technical reports and papers are published in the bimonthly Journal of Bridge Engineering (7). It covers almost any topic related to bridges, and is offered free online by the American Society of Civil Engineers. Fun activities for grade school students are given on this page (8). Separated into three levels of difficulty, the projects give students freedom to learn about and design any kind of bridge structure that interests them. A list of materials and criteria are given, but there are few explicit instructions, allowing for maximum creativity.

Leske, Cavin.

2002-01-01

76

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

77

A new isolated bidirectional buck-boost PWM converter  

Microsoft Academic Search

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

M. Delshad; H. Farzanehfard

2010-01-01

78

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

SciTech Connect

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 period is reduced to zero, allowing the lagging-leg switches to be operated with zero-current-switching (ZCS). Meanwhile, the leading-leg switches are still operated with ZVS. The new converter is attractive for high-voltage (400--800 V), high-power (2--10 kW) applications where IGBT`s are predominantly used as the power switches. The principle of operation, features, and design considerations of the new converter are described and verified on a 2-kW, 100-kHz, IGBT-based experimental circuit.

Cho, J.G. [Korea Electrotechnology Research Inst., Changwon (Korea, Republic of). Power Electronics Div.; Sabate, J.A.; Hua, G.; Lee, F.C. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

1996-07-01

79

Basic DC-to-DC Converters  

Microsoft Academic Search

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

Barry W. Williams

2008-01-01

80

An optimal selective harmonic mitigation for cascaded H-bridge converters  

Microsoft Academic Search

In recent years, due to more intransigent regulations in the area of power quality and appearance of new grid codes which limit the maximum allowable harmonic levels, paying attention to the quality of power converters' output signal has become more important. Moreover, in order to achieve high efficiency in medium voltage and high power converters, the switching frequency has to

A. Marzoughi; H. Imaneini

2012-01-01

81

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

National Technical Information Service (NTIS)

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

A. Barnaba

1992-01-01

82

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

83

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

Microsoft Academic Search

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

M. Delshad; H. Farzanehfard

2009-01-01

84

Dual Liquid Flyback Booster for the Space Shuttle  

NASA Technical Reports Server (NTRS)

Liquid Flyback Boosters provide an opportunity to improve shuttle safety, increase performance, and reduce operating costs. The objective of the LFBB study is to establish the viability of a LFBB configuration to integrate into the shuttle vehicle and meet the goals of the Space Shuttle upgrades program. The design of a technically viable LFBB must integrate into the shuttle vehicle with acceptable impacts to the vehicle elements, i.e. orbiter and external tank and the shuttle operations infrastructure. The LFBB must also be capable of autonomous return to the launch site. The smooth integration of the LFBB into the space shuttle vehicle and the ability of the LFBB to fly back to the launch site are not mutually compatible capabilities. LFBB wing configurations optimized for ascent must also provide flight quality during the powered return back to the launch site. This paper will focus on the core booster design and ascent performance. A companion paper, "Conceptual Design for a Space Shuttle Liquid Flyback Booster" will focus on the flyback system design and performance. The LFBB study developed design and aerodynamic data to demonstrate the viability of a dual booster configuration to meet the shuttle upgrade goals, i.e. enhanced safety, improved performance and reduced operations costs.

Blum, C.; Jones, Patti; Meinders, B.

1998-01-01

85

Dual Liquid Flyback Booster for the Space Shuttle  

NASA Technical Reports Server (NTRS)

Liquid Flyback Boosters provide an opportunity to improve shuttle safety, increase performance, and reduce operating costs. The objective of the LFBB study is to establish the viability of a LFBB configuration to integrate into the shuffle vehicle and meet the goals of the Space Shuttle upgrades program. The design of a technically viable LFBB must integrate into the shuffle vehicle with acceptable impacts to the vehicle elements, i.e. orbiter and external tank and the shuttle operations infrastructure. The LFBB must also be capable of autonomous return to the launch site. The smooth integration of the LFBB into the space shuttle vehicle and the ability of the LFBB to fly back to the launch site are not mutually compatible capabilities. LFBB wing configurations optimized for ascent must also provide flight quality during the powered return back to the launch site. This paper will focus on the core booster design and ascent performance. A companion paper 'Conceptual Design for a Space Shuttle Liquid Flyback Booster' will focus on the flyback system design and performance. The LFBB study developed design and aerodynamic data to demonstrate the viability of a dual booster configuration to meet the shuttle upgrade goals, i.e. enhanced safety, improved performance and reduced operations costs.

Blum, C.; Jones, P.; Meinders, B.

1998-01-01

86

Liquid flyback booster pre-phase: A study assessment  

NASA Astrophysics Data System (ADS)

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.

1994-09-01

87

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

88

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

89

A low power topology derived from flyback with active clamp based on a very simple transformer  

Microsoft Academic Search

This paper presents and analyzes a low power (10W) topology derived from flyback with active clamp based on very simple and low cost transformers. The main feature of this flyback topology is that the ratio between magnetizing inductance and the series inductance (leakage or integrated inductor) is very low (around 10\\/1). Operation of the topology is analyzed and several transformer

P. Alou; A. Bakkali; I. Barbero; J. A. Cobos; M. Rascon

2006-01-01

90

An efficient switch-mode power supply using an AC-DC interleaved boost converter and a DC-DC full-bridge topology  

Microsoft Academic Search

This work presents the conception and analysis of a switch-mode power supply with desirable characteristics of high power factor, low harmonic distortion, regulated output voltage, and high efficiency. An interleaved boost converter associated with a nondissipative snubber is used as a preregulator stage. Additionally, a soft switching full-bridge converter is chosen as DC-DC stage. The combination of both topologies results

Fernando Lessa Tofoli; Carlos Alberto Gallo

2011-01-01

91

Characteristics of an equidistant firing system in 12-pulse converter bridges for HVDC  

NASA Astrophysics Data System (ADS)

The construction of a simulation model for a twelve pulse HVDC transmission line is discussed. The realized equidistant pulse phase control system is suitable for the operation in weak or strongly unbalanced ac systems from the viewpoint of harmonic instability and suppression of abnormal harmonic currents. The phase of the firing pulses is proportional to an absolute level of the control voltage, and the operation with a constant control angle is possible. The synchronism with an ac system is guaranteed by a phase-locked loop, not by the main control loop. Thus quick and ideal response is obtaind. The measurements show that this kind of grid conrol is stable also in many faulty conditions. Abnormal harmonic generation of the converter is very small compared with the traditional systems by utilizing this kind of grid control.

Juslin, K.; Laiho, Y.; Vauhkonen, V.

1981-05-01

92

A new zero voltage switching buck-boost bidirectional DC_DC converter  

Microsoft Academic Search

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

Majid Delshad; M. Mahdavi

2010-01-01

93

Analysis of implementation possibilities and benefits of three-level half-bridge NPC topology in static auxiliary converters for rolling stock  

Microsoft Academic Search

This paper is focused on the high-voltage (ges2 kV) high-power (ges20 kW) isolated DC\\/DC converters for the rolling stock applications. The 3.3 kV IGBT based three-level half-bridge neutral point clamped (NPC) inverter topology was analyzed as an alternative to the two-level half-bridge with 6.5 kV IGBTs. The properties of primary switches, theirs selection procedure as well as inverter loss distribution

Dmitri Vinnikov; Tanel Jalakas; Indrek Roasto

2009-01-01

94

Design and Comparison of 4kV Neutral-Point-Clamped, Flying-Capacitor, and Series-Connected H-Bridge Multilevel Converters  

Microsoft Academic Search

This paper describes the design of a (4-kV, 4.16-MVA) three-level neutral-point-clamped-, three-level flying-capacitor-, four-level flying-capacitor-, and nine-level seriesconnected H-bridge voltage-source converter on the basis of state-of-the-art 6.5-, 4.5-, 3.3- and 1.7-kV insulated gate bipolar transistors. The semiconductor loss distribution and the design of semiconductors and passive components are compared for a medium switching frequency assuming a constant converter efficiency of

Seyed Saeed Fazel; Steffen Bernet; Dietmar Krug; Kamran Jalili

2007-01-01

95

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

96

Protection and regulation on direct-direct chopping converters  

NASA Astrophysics Data System (ADS)

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

Barnaba, Alphonse

1992-01-01

97

Protection and regulation on direct-direct chopping converters  

Microsoft Academic Search

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

Alphonse Barnaba

1992-01-01

98

Control of the reactive line current provided by a Dual-Bridge Matrix Converter using the input-output feedback linearization approach  

Microsoft Academic Search

A new time-invariant reduced-order model expressed in the d-q rotating reference frame of a three-phase dual-bridge matrix converter is presented. Then, a closed-loop control of the reactive component of the line current is developed. The proposed control-law uses the input-output feedback linearization approach. It allows a unity input power factor operation independently of the voltage transfer ratio variation as well

M. hamouda; F. Fnaiech; K. Al-Haddad

2006-01-01

99

An adaptive reconfigurable dc-dc converter for renewable energy applications  

Microsoft Academic Search

A new adaptive reconfigurable flyback dc-dc converter topology is provided that can be used in a wide range of applications including PV energy systems. It provides the ability for plug and play use, as the output power can be adjusted by varying the energy passing through the reconfigurable secondary winding. A variable turn's ratio configuration adopted in the proposed converter

Muhammad F. Zulfiqar; Mahmoud Alahmad

2009-01-01

100

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

Microsoft Academic Search

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

Yuancheng Ren; Xiehua Wu; Zhaoming Qian; Ken Ruan

2000-01-01

101

Average modeling and analysis of a Flyback with Active Clamp topology based on a very simple transformer  

Microsoft Academic Search

This paper presents the average model and analyzes the dynamics of a low power (10W) topology derived from Flyback with Active Clamp based on very simple and low cost transformers. The main feature of this Flyback topology is that the ratio between magnetizing inductance and the series inductance (leakage or integrated inductor) is very low (around 10\\/1). Operation of the

A. Bakkali; P. Alou; J. A. Oliver; J. A. Cobos

2007-01-01

102

An Interleaved AC–DC Converter Based on Current Tracking  

Microsoft Academic Search

In this paper, an interleaved AC-DC converter based on current tracking without any current sharing required is presented and applied to a two-phase flyback converter. This is realized using two critical-conduction-mode (CRM) pulsewidth-modulated chips, together with a field-programmable gate array technique. By doing so, not only are the total harmonic distortion and the power factor improved but the output power

K. I. Hwu; Y. T. Yau

2009-01-01

103

A Hamiltonian viewpoint in the modeling of switching power converters  

Microsoft Academic Search

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

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

1999-01-01

104

A novel full bridge type novel delta-sigma modulated power factor correction converter applying pulse space modulation technique  

Microsoft Academic Search

With the evolution of power semiconductor device technology, static high frequency switched mode power converters and inverters are now being realized. In the field of high-frequency switching power converters, the pulse width modulation (PWM) technique is widely used, but this technique has the problem of appearance of noise peaks at whole switching frequency numbers. This is a disadvantage from the

Satoshi Nagai; Yoshimi Yunoki; Atsushi Hirota; Mutsuo Nakaoka

2001-01-01

105

A Pi-based control scheme for primary cascaded H-bridge rectifier in transformerless traction converters  

Microsoft Academic Search

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue

Tao Xinghua; Li Yongdong; Sun Min

2010-01-01

106

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

107

A detailed RL fed bridge converter model for power flow studies in industrial AC\\/DC power systems  

Microsoft Academic Search

Because of lower voltage levels and smaller power ratings, the R\\/X ratio of commutation impedance in industrial AC\\/DC distribution systems is usually higher than that in HVDC transmission systems. Considerable discrepancies may therefore occur in industrial AC\\/DC power flow results, especially the reactive power consumption of converters, if the commutation resistances of the converters are neglected. To describe the effects

Yii-Shen Tzeng; Nanming Chen; Ruay-Nan Wu

1995-01-01

108

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

109

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

110

Commercial Frequency AC to High Frequency AC Converter With Boost-Active Clamp Bridge Single Stage ZVS-PWM Inverter  

Microsoft Academic Search

This paper presents a novel soft-switching pulsewidth modulation (PWM) utility frequency ac to high frequency (HF) ac power conversion circuit incorporating boost-active clamp single stage inverter topology. This power converter is more suitable and acceptable for cost effective HF consumer induction heating applications. Its operating principle is presented using the switching mode equivalent circuits in addition to the operating voltage

Bishwajit Saha; Soon Kurl Kwon; Nabil A. Ahmed; Hideki Omori; Mutsuo Nakaoka

2008-01-01

111

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

112

A power-equalized harmonic-elimination scheme for utility-connected cascaded H-bridge multilevel converters  

Microsoft Academic Search

Although fundamental frequency switching has been the preferred method for high-power medium-voltage multilevel converters, the technology of current generation power semiconductors has made it possible to use higher rates. In utility-connected applications, where a restricted modulation index range is usually sufficient, a main requirement is for very tight control over individual harmonics. For these reasons, this paper considers the application

Joseph Vassallo; Jon C. Clare; Patrick W. Wheeler

2003-01-01

113

Discrete time domain small-signal modeling of full-bridge phase-shifted series resonant converter  

Microsoft Academic Search

This paper provides an analytical discrete small-signal state-space model of the phase-shift modulated series resonant converter used to obtain an explicit linearized phase-shift to output voltage transfer function. This transfer function is useful for linear closed loop control design. Initially, the effective duty-ratio to output voltage transfer function is derived. It is then proven, analytically and through results, that it

A. A. Aboushady; K. H. Ahmed; S. J. Finney; B. W. Williams

2010-01-01

114

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

115

A single switch boost-flyback DC-DC converter integrated with switched-capacitor cell  

Microsoft Academic Search

Without extreme duty ratio or complexity of circuits, by employing coupled-inductor and switched-capacitor cell achieved high voltage conversion ratio with a single switch is proposed in this paper. Coupled-inductor transfer source energy to secondary side through entire switching period, the leakage energy of coupled inductor is efficiently recycled; the inrush current problem on switched capacitors was restrained by leakage inductor

Tsorng-Juu Liang; Shih-Ming Chen; Lung-Sheng Yang; Jiann-Fuh Chen; Adrian Ioinovici

2011-01-01

116

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

117

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

118

Recognition of dynamic patterns in dc-dc switching converters  

NASA Astrophysics Data System (ADS)

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

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

119

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

120

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

121

Power converter  

NASA Technical Reports Server (NTRS)

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

Black, J. M. (inventor)

1981-01-01

122

Topology, Development, and Control of a Three-Port Triple-Half-Bridge DC-DC Converter for Hybrid Energy Storage Application  

Microsoft Academic Search

Recently, hybrid battery and ultracapacitor has growing applications in electrical vehicle, electric ship and distributed renewable energy generation to achieve higher overall performance. Most of the power electronics interface of hybrid battery and ultracapacitor is realized by connecting individual dc-dc converters. However, the advantages of using integrated power converters with multiple interfacing ports, which is defined as multi-port converter, instead

Danwei Liu

2006-01-01

123

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

124

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

125

A computer-aided design and simulation tool for switching converters  

NASA Astrophysics Data System (ADS)

A fully automated computer-aided design approach is presented which results in an optimal power stage and control circuit design. The design meets all dc, small signal and large signal closed-loop performance specifications. The proposed approach is efficient. It can help in reducing component and manufacturing costs as well as design time and has been successfully demonstrated on a multiple-output flyback converter breadboard.

Kelkar, S. S.; Ridley, R. B.; Hsiao, C. J.; Ramkumar, R.; Lee, F. C.

126

An averaged modeling technique for dc to dc converters developed for the Space Station Freedom dc to dc Converter Unit (DDCU)  

NASA Astrophysics Data System (ADS)

An averaged modeling technique for dc to dc converters has been developed and applied to the dc to dc Converter Unit (DDCU) of the Space Station Freedom. The averaged model can be used for frequency domain, transient, and steady-state simulations. The DDCU model derivation is included to demonstrate a technique for modeling other complex topologies. The equations for a special case of the Weinberg topology where the power transformer and flyback transformer turns ratios are different are also included. Averaged modeling results have been correlated with test data as well as linearized small signal and full order switching model results.

Needham, Bruce R.

127

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

128

Single-Stage Power-Factor-Correction Circuit with Flyback Converter to Drive LEDs for Lighting Applications  

Microsoft Academic Search

White light emitting diode (LED) with high brightness has attracted a lot of attention from both industry and academia for its high efficiency, ease to drive, environmental friendliness, and long lifespan. They become possible applications to replace the incandescent bulbs and fluorescent lamps in residential, industrial and commercial lighting. The realization of this new lighting source requires both tight LED

Ying-Chun Chuang; Yu-Lung Ke; Hung-Shiang Chuang; Chia-Chieh Hu

2010-01-01

129

Fast Referenceless PRF Thermometry Using Spatially Saturated, Spatial-spectrally Excited Flyback EPI  

NASA Astrophysics Data System (ADS)

High intensity focused ultrasound (HIFU) is a promising technique for noninvasive treatment of liver tumors. To safely monitor HIFU, accurate temperature measurements must be acquired. However, respiratory motion impairs the performance of conventional MR-guided PRF-thermometry sequences, leading to inaccurate temperature measurements and locations. We developed an MR imaging system to minimize these with the following key elements: imaging at 3.62 frames/sec and utilizing real-time referenceless thermometry processing. A spatially saturated, spectral-spatially excited flyback echo planar readout pulse sequence that allows rapid temperature acquisition was developed. The spatial-spectral pulse ignores lipids, and other off-resonance effects are mitigated with linear delays of the EPI readout. The saturation pulse restricts the field of view in the phase encode direction, allowing for increased resolution without aliasing. The pulse sequence was constructed in RTHawk, a real time MR environment, and tested by creating lesions in a phantom using the ExAblate 2000 (Insightec, Haifa, Israel). The experiment was performed when the transducer and phantom were stationary and when both were manually moved back and forth to simulate respiratory motion. Both lesions mainly followed the same shape, and the lesion appeared as a round growing spot during motion. The real-time sequence in conjunction with referenceless thermometry is promising for HIFU in the presence of motion.

Holbrook, Andrew B.; Kaye, Elena; Santos, Juan M.; Rieke, Viola; Pauly, Kim Butts

2009-04-01

130

Bridge permeameter  

DOEpatents

A system for single-phase, steady-state permeability measurements of porous rock utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors.

Graf, Darin C. (Edgewood, NM); Warpinski, Norman R. (Albuquerque, NM)

1996-01-01

131

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

132

Designing Bridges  

NSDL National Science Digital Library

Students learn about the types of possible loads, how to calculate ultimate load combinations, and investigate the different sizes for the beams (girders) and columns (piers) of simple bridge design. Students learn the steps that engineers use to design bridges: understanding the problem, determining the potential bridge loads, calculating the highest possible load, and calculating the amount of material needed to resist the loads.

Integrated Teaching And Leaning Program And Laboratory

133

Spaghetti Bridge  

NSDL National Science Digital Library

In this engineering activity, learners investigate the differences between the strength of bridges made from flat and round building materials. They construct simple bridges out of linguine, which has a rectangular shape, and spaghetti, which has a circular shape. They then test and compare the weight capacity of the bridges.

Cosi

2009-01-01

134

Spaghetti Bridge  

NSDL National Science Digital Library

Civil engineers design structures such as buildings, dams, highways and bridges. Students explore the field of engineering by making a bridge 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

Bridge permeameter  

DOEpatents

A system is described for single-phase, steady-state permeability measurements of porous rock which utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors. 8 figs.

Graf, D.C.; Warpinski, N.R.

1996-08-13

136

Digital Bridges  

NSDL National Science Digital Library

"The Digital Bridges Web site consists of a collection of thirty representative 19th century American bridge engineering monographs, manuals, and documents from the Lehigh University Libraries' Special Collections." The archive provides an interesting retrospective into the beginnings of major bridge projects; the material is complete with high-resolution photographs and text scanned from original books. In addition to historical literature, Digital Bridges also features brief accounts of notable people and companies that influenced bridge construction across the country. A glossary of terms commonly used in the documents is also provided.

2002-01-01

137

Bidirectional converter interface for a battery energy storage test bench  

Microsoft Academic Search

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

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

2011-01-01

138

Spaghetti Bridge  

NSDL National Science Digital Library

Learners explore the field of civil engineering by making a bridge using spaghetti as their primary building material. Then they test their bridges to see how much weight they can carry before breaking. This activity allows learners to engage in the entire engineering process as they design, build, test, then discuss their bridges. Resource includes investigating questions to extend learning. Time estimated for activity can be split across multiple meetings.

Institute, Worcester P.

2005-01-01

139

Soft switching active snubbers for DC/DC converters  

SciTech Connect

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

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

1996-09-01

140

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

141

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

142

Safer Bridges  

NASA Technical Reports Server (NTRS)

Safer bridges are among a number of spinoff benefits from NASA procedures for testing 'cfracture toughness" of a structural part, meaning its ability to -siscracktsh at might cause failure. The New River Bridge in West Virginia, shown under construction, is the world's largest single span bridge. U.S. Steel fracture toughness requirements for such bridges include NASA-developed test procedures. Bridge materials and other metal structures may develop flaws during their service lifetimes. Such flaws can affect the structural integrity of the part. Thus, it is important to know the "fracture toughness" of a structural part, or its ability to resist cracks. NASA has long experience in developing fracture toughness tests for aerospace hardware. Since 1960, NASA-Lewis has worked closely with the American Society for Testing & Materials. Lewis and NASA-funded industrial contractors have made many important contributions to test procedures, now recommended by ASTM, for measuring fracture toughness.

1977-01-01

143

Thermophotovoltaic converter  

SciTech Connect

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

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

1982-05-25

144

Cable Stayed Timber Bridges.  

National Technical Information Service (NTIS)

A growing market segment open to timber bridges is pedestrian bridges crossing highways, railways and watercourses. These bridges are often calling for a long span and large vertical clearance under the bridge. Suspended and cable stayed bridges are attra...

A. Pousette

2001-01-01

145

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

Microsoft Academic Search

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

Shweta Gautam; Anil Kumar Yadav; Rajesh Gupta

2012-01-01

146

Bridging Anticoagulation  

MedlinePLUS

... Institution: NIH Library User Name Password Sign In Cardiology Patient Page Bridging Anticoagulation Is it Needed When ... Extract Free » Full Text Free PDF Free Classifications Cardiology Patient Page Services E-mail this article to ...

147

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

148

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

149

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

150

Interleaved converters based on hysteresis current control  

Microsoft Academic Search

A method is proposed to improve the interleaved operation of half-bridge converters with variable switching frequency. It is based on cycle-by-cycle measurements of the switching period of one module, with the needed phase shift for the other bridges obtained by means of analog circuitry to allow fast dynamic response. Furthermore, in case of failure of one module, phase shift can

J. S. Batchvarov; J. L. Duarte; M. A. M. Hendrix

2000-01-01

151

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

152

Bridges, 2002.  

ERIC Educational Resources Information Center

This document is comprised of the one issue in volume 7 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 2002 issue focuses on several topics of interest to…

Silver, Michael, Ed.; Zito, Michael, Ed.

2002-01-01

153

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

154

Bridges, 1999.  

ERIC Educational Resources Information Center

This volume contains articles about writing, best practice, portfolio assessment, and technology, as well as original poetry and book reviews. Articles in the volume are: "Teaching Writing: Making Connections" (Eric Schott); "Empowering Teachers: A Success Story" (Sandra L. Krivak); "Bridging the Gap between the Classroom and Employment" (Linda C.…

Wilcox, Bonita; Manear, John; Slifkin, Josh M.

155

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.

156

The Belizean Bridge Activity.  

ERIC Educational Resources Information Center

Describes the famous swing bridge in Belize. Students build bridges from a variety of materials and answer the questions, What are different types of bridges?, How do bridges work?, How can you tell if a bridge design will be safe?, and What is the best way to build a bridge over a river while still allowing boat traffic? (SAH)

Murfin, Brian

2000-01-01

157

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

158

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

159

Multi-objective optimization of LCC resonant converter applied in VLF HV generator  

Microsoft Academic Search

The demands for decreasing cost and increasing efficiency are popular for converter systems. In high voltage converter systems, such demands become more important and emergent since it is well-known that high voltage converter systems often consume greater cost and has lower efficiency compared with usual one. In this paper, a LCC resonant converter, which is comprised of full-bridge inverter, LCC

Manli Hu; Norbert Froehleke; Wilhelm Peters; Joachim Boecker

2011-01-01

160

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

161

Convertible Stadium  

NASA Technical Reports Server (NTRS)

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

1978-01-01

162

Analysis, control and modeling of cascaded multilevel converter-based IPC  

Microsoft Academic Search

This paper proposes a novel interphase power controller (IPC) based on multilevel cascaded H-bridge converters, which are fed by diode bridge sources. In the proposed structure the fundamental modulation scheme is applied to decrease the switching loss in the converters. Furthermore, in this paper the mathematical model of IPC is derived. Based on this model a new method with the

Afshin Samadi; Shahrokh Farhangi

2008-01-01

163

A novel power converter for photovoltaic applications  

NASA Astrophysics Data System (ADS)

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

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

164

LCLC resonant converter for multiple lamp operation ballast  

Microsoft Academic Search

This paper presents a design methodology, analysis, and practical considerations of LCLC resonant converter for multiple lamp operation ballast. According to the basic requirements of multiple lamp operation ballast (MLOB), the design procedure can be outlined to determine resonant parameter. Consequently, independent MLOB can be achieved under voltage-source half-bridge LCLC resonant converter with zero voltage switching (ZVS). Finally, some experimental

Chenyang Liu; Fanghua Teng; Changsheng Hu; Zhongchao Zhang

2003-01-01

165

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

166

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

167

Research on control type soft switching converters  

Microsoft Academic Search

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

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

2004-01-01

168

Bidirectional power electronics for driving dielectric elastomer transducers  

NASA Astrophysics Data System (ADS)

The operation of Dielectric Elastomer Transducers typically requires high voltages in the kilovolt range and relatively low currents. Therefore, for driving Dielectric Elastomer Transducers a high voltage power electronics is necessary. For realization of energy efficient actuator and generator applications bidirectional switched-mode converter topologies should be used enabling a bidirectional energy transfer as well as a high efficiency. In this contribution a modular converter system consisting of several switched-mode converter modules featuring galvanic isolation is presented as a basic concept for realization of a high voltage power supply. Three converter topologies - bidirectional flyback, Dual Active Bridge and Isolated Bidirectional Full-Bridge converter - are investigated and suitable modulation schemes are presented, which are based on hysteretic current-mode control, enabling a high converter dynamic and limitation of the converter output current in order to prevent electrode damage. Simulation results for the proposed converter topologies are presented and experimental results for a single bidirectional flyback converter module are shown.

Eitzen, L.; Graf, C.; Maas, J.

2012-03-01

169

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

170

Bridge Needs, Design, and Performance,  

National Technical Information Service (NTIS)

The 14 papers in the report deal with the following areas: bridge strengthening needs in the United States; a bridge automated design and drafting system; bridge deck expansion joints; nonlinear analysis of highway bridges; prestressed waffle slab bridges...

K. F. Dunker F. W. Klaiber W. W. Sanders T. J. Tiberio J. C. Hayward

1987-01-01

171

A minimized switch count single-phase AC\\/AC converter with active front end  

Microsoft Academic Search

A three-switch single-phase converter is introduced in this paper which is a counterpart to back-to-back half-bridge converters. Introducing the new converter and elaborating its modulation scheme, a single-phase ac\\/ac converter is proposed based on it. The proposed topology enjoys the benefits of an ideal single-phase ac\\/ac converter such as low THD input current, unity power factor, fast dynamic response and

A. Fatemi; M. Azizi; M. Mohamadian; F. Ashrafzadeh

2012-01-01

172

Bridging the Gaps  

NSDL National Science Digital Library

Students are presented with a brief history of bridges as they learn about the three main bridge types: beam, arch and suspension. They are introduced to two natural forces â tension and compression â common to all bridges and structures. Throughout history, and today, bridges are important for connecting people to resources, places and other people. Students become more aware of the variety and value of bridges around us in our everyday lives.

Integrated Teaching and Learning Program, College of Engineering,

173

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

174

Active power balance in cascaded multilevel converter under bipolar and unipolar modulation  

Microsoft Academic Search

Multilevel converters have turned into a mature technology that has helped their use in high power applications. This paper presents the performance comparison of the active power imbalance in the cells of a cascaded H-bridge (CHB) multilevel converter under bipolar and unipolar modulation based converter control. This paper also analyses the condition of power balance and imbalance across each cells

Vijay Kumar Singh; S. Jegannathan; Shobhit Mishra; Manojit Biswas; Rajesh Gupta

2012-01-01

175

An LCC DC\\/DC resonant converter designed for applications with variable load and output voltage  

Microsoft Academic Search

A full-bridge LCC DC\\/DC resonant power converter is presented. This power converter can operate with variable load and output voltage, enlarging typical applications of resonant power converters. Good values of efficiency and output voltage margin, as well as moderate voltages across the resonant capacitors and currents through the resonant inductor are obtained

Josep Bordonau; Rafael M. Lamaison; Juan Peracaula

1995-01-01

176

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

177

Semiconductor bridge (SCB) detonator  

Microsoft Academic Search

The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge 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

Bickes Jr. Robert W; Mark C. Grubelich

1999-01-01

178

Semiconductor bridge (SCB) detonator  

Microsoft Academic Search

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

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

1999-01-01

179

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 can occur with infections or genetic diseases. A decrease in the height of the nasal bridge is best seen from a side ...

180

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

181

Design of photovoltaic high frequency link inverter based on push-pull forward converter  

Microsoft Academic Search

In this paper, a photovoltaic high frequency link inverter is proposed. The inverter is constituted of push-pull forward DC-DC converter and DC-AC inverter full bridge. The push-pull forward converter has some superiority in low voltage high current situation and achieves electrical isolation between the photovoltaic battery and the AC output. The push-pull forward converter is used to convert the photovoltaic

Shungang Xu

2010-01-01

182

Sliding mode-a new way to control series resonant converters  

Microsoft Academic Search

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

Fares BOUDJEMA; Jean-Louis ABATUT

1990-01-01

183

Open-loop approach to control a Modular Multilevel Frequency Converter  

Microsoft Academic Search

Frequency converters are required to supply power from the public three-phase network to railways using 16.7 Hz single-phase in their rolling stock. The emerging Modular Multilevel Converter (M2C) technology offers the possibility to make such power conversion in one step using Modular Multilevel Frequency Converters (MMFC) with full-bridge sub-modules. A detailed study of the modulation and control of such converters

Lennart Angquist; Arif Haider; Hans-Peter Nee; Hongbo Jiang

2011-01-01

184

Modeling of multilevel converters  

Microsoft Academic Search

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

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

1997-01-01

185

The PWM control of modular multi-level converter  

Microsoft Academic Search

MMC (modular multilevel converter) is a voltage converter with good character, such as low harmonic, no additional filters and transformers, suitable for modular produce etc. However, due to the bridge arm of MMC cascading multiple sub-modules, balance control of the sub-module is needed, and the balance between the various sub-module control systems affect the normal operation of MMC largely. This

Jiahu Guo; Qi-yan Liao

2011-01-01

186

A wide output range reconfigurable structure dc-dc converter  

Microsoft Academic Search

The paper presents a new wide output range reconfigurable structure (WOR-RS) dc-dc converter, which is an extension of the full bridge isolated dc-dc converter with two output channels by adding an active switch and two diodes. The proposed WOR-RS is able to smoothly reconfigure the two output channels in parallel or series to realize wide output range. With this approach,

Pengju Sun; Luowei Zhou; Keyue Smedley

2010-01-01

187

Nanoparticle bridge DNA biosensor  

NASA Astrophysics Data System (ADS)

A new DNA sensing method is demonstrated in which DNA hybridization events lead to the formation of nanoparticle satellites that bridge two electrodes and are detected electrically. The hybridization events are exclusively carried out only on specific locations, the surfaces of C-ssDNA modified 50 nm GNPs. The uniqueness of this work is that only a small number of T-ccDNA molecules (<10) is required to form the nanoparticle satellites, allowing ultra-sensitive DNA sensing. The principle of this new DNA sensing technique has been demonstrated using target DNA and three-base-pair-mismatched DNA in 20nM concentrations. Three single-stranded DNA (ssDNA) system is used in our experiment which includes Capture-ssDNA (C-ssDNA), Target-ssDNA (T-ssDNA) and Probe-ssDNA (P-ssDNA). Both C-ssDNA and P-ssDNA are modified by a thiol group and can hybridize with different portions of T-ssDNA. T-ssDNA requires no modification in three ssDNA system, which is beneficial in many applications. C-ssDNA modified 50nm gold nanoparticle (C-50au) and P-ssDNA modified 30nm gold nanoparticle (P-30au) are prepared through the reaction of thiol-gold chemical bonding between thiolated ssDNA and gold nanoparticle (GNP) (C-ssDNA with 50nm GNP, P-ssDNA with 30nm GNP). We controllably place the C-50au only on the SiO2 band surface (˜ 90nm width) between two gold electrodes (source and drain electrodes) by forming positively- and negatively-charged self-assembled monolayers (SAMs) on SiO2 and gold surface, respectively. DNA modified GNP is negatively charged due to ionization of phosphate group on DNA back bone. C-50au therefore is negatively charged and can only be attracted toward SiO2 area (repelled by negatively charged gold electrode surface). The amine group of positively-charged SAMs on SiO2 surface is then passivated by converting to non-polar methyl functional group after C-50au placement. P-30au is first hybridized with T-ssDNA in the solution phase (T-P- 30au formed) and is introduced into DNA detection device in which C-50au are immobilized on ˜90nm width SiO2 band (between two gold electrodes). The passivation step ensures every TP-30au are attached only to C-50au through hybridization (T-P-30au will not be attracted toward SiO2 surface or gold electrodes). GNP bridges are formed across the electrodes and provide an electrical path between two gold electrodes. We ensure that every T-P-30au only hybridizes on the surface of C-50au by (1) accurately controlling C-50au placement between two gold electrodes, (2) passivating positively-charged SAMs on SiO2 surface after C-50au immobilization. When T-P-30au hybridize with C-50au on ˜90nm wide SiO 2 surface, GNP bridges form and provide an electrical path between two gold electrodes even with only a few hybridization events. Experimental results show that even a few GNP bridges formed on SiO2 band can provide a significant conductance change from an open circuit to a conductive circuit (current = 0.5 uA at voltage = 0.1 V with four GNP bridge). We also used 3-base-pair-mismatched ssDNA (3mm-ssDNA) as a control experiment, which always resulted in an open circuit (no GNP bridge formed). Our detection device is compatible with current CMOS fabrication technology and can be manufactured on a wafer scale. The direct electrical output of this DNA detection technique provides a promising basis for high-throughput screening (can be fabricated on a wafer scale) with no expensive equipment required.

Huang, Hong-Wen

188

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

189

Embedded controlled low-frequency AC to high-frequency AC converter fed induction heater  

Microsoft Academic Search

Purpose – The purpose of this paper is to present, a novel boost-active clamp bridge single stage high-frequency zero voltage soft-switching-pulse width modulation (ZVS-PWM) inverter, which converts the utility frequency AC power into high-frequency AC power with an embedded controller. This single stage high-frequency inverter is composed of a single-phase diode bridge rectifier, a non-smoothing filter, a boost-active clamp bridge

Kirubakaran Dhandapani; Rama Reddy Sathi

2011-01-01

190

Boost bridge audio amplifier  

Microsoft Academic Search

The main difference in topology of a boost bridge amplifier and state-of-the-art class-D amplifier is in the connection of a loudspeaker between a power supply and a switching bridge. The boost bridge amplifier provides four times higher peak power at the loudspeaker than the power, which can be achieved by a class-D amplifier from the same power supply. Total harmonic

Milan Prokin

2001-01-01

191

Convertible Exchangeable Preferred Stock  

Microsoft Academic Search

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

Arnold R. Cowan

1996-01-01

192

Semiconductor bridge (SCB) detonator  

SciTech Connect

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

193

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.

194

GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE ...  

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

GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE IN FOREGROUND - Goethals Bridge, Spanning Arthur Kill from New Jersey to Staten Island, Staten Island (subdivision), Richmond County, NY

195

DISTANT ELEVATION, NOTE CREEK BRIDGE FOREGROUND, COVERED BRIDGE OVER DIFFERENT ...  

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

DISTANT ELEVATION, NOTE CREEK BRIDGE FOREGROUND, COVERED BRIDGE OVER DIFFERENT STREAM IN THE BACKGROUND, NORTHEAST PORTAL - Larwood Bridge, Spanning Crabtree Creek, Fish Hatchery Road (CR 648), Lacomb, Linn County, OR

196

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...  

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

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM BELOW, SHOWING VALVE TOWER TO RIGHT. VIEW FACING NORTH - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

197

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...  

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

APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM ENTRY. VIEW FACING NORTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream East Range, Wahiawa, Honolulu County, HI

198

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

199

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

200

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

201

Three-Phase Hybrid Multilevel Inverter Based on Half-Bridge Modules  

Microsoft Academic Search

A novel three-phase hybrid multilevel converter is proposed for medium-voltage applications. The converter employs a conventional three-phase voltage source inverter (VSI) linking series connected half-bridge modules at each phase. With the proposed connection, a large portion of energy can be processed by the VSI by employing a single multi-pulse rectifier, while smaller power shares are processed within the half-bridge modules.

Alessandro Luiz Batschauer; Samir Ahmad Mussa; Marcelo Lobo Heldwein

2012-01-01

202

TWIN SKEWED TRUSS RAILROAD BRIDGES NEAR BRIDGE STREET AT THE ...  

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

TWIN SKEWED TRUSS RAILROAD BRIDGES NEAR BRIDGE STREET AT THE WEST END OF THE PLANT. THIS VIEW PROBABLY LOOKING NORTHWEST. BRIDGES BUILT OVER ERIE CANAL (WHICH FLOWED RIGHT THROUGH THE MIDDLE OF THE PLANT) BY AMERICAN BRIDGE COMPANY IN 1902. SINCE THIS PHOTO WAS TAKEN, NEAR BRIDGE HAS BEEN DEMOLISHED; FAR BRIDGE IS STILL IN SERVICE. - Solvay Process Company, Between Willis & Milton Avenues, Solvay, Onondaga County, NY

203

Parametric energy converter  

Microsoft Academic Search

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

Johnson

1981-01-01

204

The microminiature thermionic converter  

Microsoft Academic Search

The design, fabrication, testing, and analysis of the microminiature thermionic converter (MTC) is discussed. MTCs are two electrode devices that convert heat energy into electrical energy. The electrodes are spaced opposite each other in a vacuum environment with one electrode heated and the second cooled. Electrons are emitted from the hot electrode to the cool electrode creating electrical power. The

Donald Bryan King

2000-01-01

205

Variable Geometry Torque Converter.  

National Technical Information Service (NTIS)

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

K. W. Benn G. L. Perrone

1978-01-01

206

Sulphite Railroad Bridge1896, Title Sheet Sulphite Railroad Bridge, Former ...  

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

Sulphite Railroad Bridge-1896, Title Sheet - Sulphite Railroad Bridge, Former Boston & Maine Railroad (originally Tilton & Franklin Railroad) spanning Winnipesautee River, Franklin, Merrimack County, NH

207

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

208

Bridges and Culverts.  

National Technical Information Service (NTIS)

The 16 papers in this report deal with the following areas: field testing of the Fremont Bridge; seismic design of curved box girders; test to failure of the Hannacroix Creek Bridge; load factor design applied to truss members in design of Greater New Orl...

M. J. Koob J. M. Hanson C. P. Heins I. C. Lin D. B. Beal

1983-01-01

209

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

210

Support Column of Bridge  

USGS Multimedia Gallery

Support column of bridge across Struve Slough, Highway 1. Enlargement of hole where support enters the ground is an effect of lateral shaking, which caused the concrete to break up where the column joined the bridge and was instrumental in the roadbed collapse....

2009-01-26

211

1.2 MW dc-dc converter  

NASA Astrophysics Data System (ADS)

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

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

1993-01-01

212

Bridge and Hydrology Research, 1991.  

National Technical Information Service (NTIS)

Partial Contents: Aesthetically Pleasing Steel Pipe Bridge Rail; Oak A-Frame Timber Bridges Meeting the Modern Deflection Requirement; Behavior and Design of Moment-Reducing Details for Bridge Column-Foundation Connections; Climbing: A Unique and Effectiv...

1991-01-01

213

Constant Current Strain Gauge Bridge.  

National Technical Information Service (NTIS)

All the early electrical strain gauge bridge circuits employed constant voltage sources for bridge excitation. The techniques developed for the classical direct-current and alternating-current component-measuring bridges were transferred to the strain gau...

E. S. Moody

1984-01-01

214

DC circulating current for capacitor voltage balancing in modular multilevel matrix converter  

Microsoft Academic Search

A high voltage matrix converter for interconnecting two AC power networks has been described previous in which the links bridging the phases of the two AC networks are formed from a large number of capacitive submodules linked in series. The operation of the converter was described, including the method of maintaining the charge in the individual submodules equal within a

Colin Oates; Gopal Mondal

2011-01-01

215

Operation of a modular multilevel converter with selective harmonic elimination PWM  

Microsoft Academic Search

The modular multilevel converter (MMC) is based on the cascaded interconnection of half-bridge switching sub- modules and features modular characteristics that allow its expandability while providing high quality voltage and current output waveforms and removing the need for filtering. The switching frequency of each of the individual converter sub modules being maintained low and the balancing of the capacitor voltages

Georgios S. Konstantinou; Mihai Ciobotaru; Vassilios G. Agelidis

2011-01-01

216

A new soft switching direct converter for residential fuel cell power system  

Microsoft Academic Search

In this paper a new soft switching direct converter suitable for residential fuel cell system is discussed. The proposed system consists of two power stages which are soft switching full bridge dc\\/dc converter and three phase voltage source inverter without dc link capacitors. A new PWM strategy (with different placement of the zero-vector) for the 3 phase inverter is presented

Han Ju Cha; Prasad N. Enjeti

2004-01-01

217

A Simple, Passive 24Pulse AC–DC Converter With Inherent Load Balancing  

Microsoft Academic Search

A new converter topology for a three-phase multipulse rectifier circuit is described. This converter draws almost sinusoidal currents from the ac system with very low harmonic content and typically less than 3% total harmonic distortion. The topology uses only passive components and has a lower component count than other rectifier circuits with similar performance. Two six-pulse rectifier bridges are connected

F. Javier Chivite-Zabalza; Andrew J. Forsyth; David R. Trainer

2006-01-01

218

State space representation of current converters in extensive three-phase AC systems  

Microsoft Academic Search

In this paper the approach for the calculation of networks, including current converter bridges presented previously by the authors (1996, 1997) is adapted to extensive 3-phase AC systems. It still utilises the periodicity of all state variables in steady-state operating mode. The entire system consisting of the entire 3-phase network, the current converter and the DC network is represented in

G. Herold; C. Weindl

1998-01-01

219

Building Our Bridge to Fun!  

NSDL National Science Digital Library

Students identify different bridge designs and construction materials used in modern day engineering. They work in construction teams to create paper bridges and spaghetti bridges based on existing bridge designs. Students progressively realize the importance of the structural elements in each bridge. They also measure vertical displacements under the center of the spaghetti bridge span when a load is applied. Vertical deflection is measured using a LEGO® MINDSTORMS® NXT intelligent brick and ultrasonic sensor. As they work, students experience tension and compression forces acting on structural elements of the two bridge prototypes. In conclusion, students discuss the material properties of paper and spaghetti and compare bridge designs with performance outcomes.

Applying Mechatronics to Promote Science (AMPS) GK-12 Program,

220

Microminiature thermionic converters  

DOEpatents

Microminiature thermionic converts (MTCs) having high energy-conversion efficiencies and variable operating temperatures. Methods of manufacturing those converters using semiconductor integrated circuit fabrication and micromachine manufacturing techniques are also disclosed. The MTCs of the invention incorporate cathode to anode spacing of about 1 micron or less and use cathode and anode materials having work functions ranging from about 1 eV to about 3 eV. Existing prior art thermionic converter technology has energy conversion efficiencies ranging from 5-15%. The MTCs of the present invention have maximum efficiencies of just under 30%, and thousands of the devices can be fabricated at modest costs.

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

2001-09-25

221

Advanced thermionic converter development  

NASA Technical Reports Server (NTRS)

Recent progress at Thermo Electron in developing advanced thermionic converters is summarized with particular attention paid to the development of electrodes, diodes, and triodes. It is found that one class of materials (ZnO, BaO and SrO) provides interesting cesiated work functions (1.3-1.4 eV) without additional oxygen. The second class of materials studied (rare earth oxides and hexaborides) gives cesiated/oxygenated work functions of less than 1.2 eV. Five techniques of oxygen addition to thermionic converters are discussed. Vapor deposited tungsten oxide collector diodes and the reflux converter are considered.

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

1976-01-01

222

Fluorescent radiation converter  

NASA Technical Reports Server (NTRS)

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

Viehmann, W.

1980-01-01

223

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

224

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

225

Efficient and ripple-mitigating dc–dc converter for residential fuel cell system  

Microsoft Academic Search

Proton exchange membrane fuel cell (PEMFC) systems for residential application require efficient and ripple-mitigating power conditioning system (PCS). The key point to reach it, is the design and control of the dc–dc converter. Based on the theoretical and experimental analysis of the traditional converter, this paper proposes a novel parallel-series full bridge (P-SFB) dc–dc converter, and improves its phase shifting

Yong Wang; Seeyoung Choi; Eunchul Lee

2009-01-01

226

Relay based digital auto-tuning techniques for isolated DC-DC switching converters  

Microsoft Academic Search

A simple auto-tuning technique, based on the relay feedback, for voltage-mode synchronous half bridge isolated POL converter is here reported. By means of the relay control, small oscillations on the output voltage are generated during converter soft-start. Based on the measurements of the frequency and amplitude of the oscillations, the gain and phase of the converter transfer function at the

Andrea Pizzutelli; Alberto Carrera; Stefano Saggini

2007-01-01

227

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

Microsoft Academic Search

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

Richard Morrison; Michael G. Egan

2001-01-01

228

Wheatstone Bridge Learning Module  

NSDL National Science Digital Library

This page from the Southwest Center for Microsystems Education features a learning module on the electronic circuitry of a Wheatstone bridge. After completing the unit, students will be able to define the variable components of the Wheatstone bridge and describe how it works.A participant guide, instructor guide (both in PDF format) and two Power Point presentations (one on the Wheatstone bridge and another with a pressure sensor activity) are included. Users are encouraged to register and log in in order to access the full content on the site.

2011-10-11

229

Wirephoto Standards Converter.  

National Technical Information Service (NTIS)

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

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

1968-01-01

230

Circuit bridging of components by smoke  

SciTech Connect

Smoke can adversely affect digital electronics; in the short term, it can lead to circuit bridging and in the long term to corrosion of metal parts. This report is a summary of the work to date and component-level tests by Sandia National Laboratories for the Nuclear Regulatory Commission to determine the impact of smoke on digital instrumentation and control equipment. The component tests focused on short-term effects such as circuit bridging in typical components and the factors that can influence how much the smoke will affect them. These factors include the component technology and packaging, physical board protection, and environmental conditions such as the amount of smoke, temperature of burn, and humidity level. The likelihood of circuit bridging was tested by measuring leakage currents and converting those currents to resistance in ohms. Hermetically sealed ceramic packages were more resistant to smoke than plastic packages. Coating the boards with an acrylic spray provided some protection against circuit bridging. The smoke generation factors that affect the resistance the most are humidity, fuel level, and burn temperature. The use of CO{sub 2} as a fire suppressant, the presence of galvanic metal, and the presence of PVC did not significantly affect the outcome of these results.

Tanaka, T.J.; Nowlen, S.P.; Anderson, D.J. [Sandia National Labs., Albuquerque, NM (United States)

1996-10-01

231

Multilevel converters -- A new breed of power converters.  

National Technical Information Service (NTIS)

Multilevel voltage source converters are emerging as a new breed of power converter options for high-power applications. The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc capacitor voltages....

J. S. Lai F. Z. Peng

1995-01-01

232

PDF to HTML Converter  

NSDL National Science Digital Library

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

2010-01-01

233

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

234

X-ray converter  

US Patent & Trademark Office Database

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

2009-02-24

235

Implant-Supported Bridge  

MedlinePLUS

... dental lab. Porcelain-fused-to-metal bridge The restoration (the part that looks like teeth) is a ... who has advanced training in the placement and restoration of implants. Your dentist will do a comprehensive ...

236

Magnetic Bridge Proximity Sensor.  

National Technical Information Service (NTIS)

A proximity sensor for indicating the spatial proximity of a ferrous object comprising a magnetic reluctance bridge formed from a plurality of high and low permeability sections and with a ring core flux gate magnetometer disposed therebetween to form the...

F. W. Heemstra

1982-01-01

237

Clinical Study of Myocardial Bridge  

Microsoft Academic Search

Background and Objectives:Myocardial bridge is a congenital coronary anomaly that causes myocardial ischemia by a milking effect. The general study of myocardial bridge is weak, therefore we retrospectively examined clinical records of cases of myocardial bridge. Materials and Method:This study included 36 bridge cases out of 1048 patients who underwent coronary angiography due to chest pain from Jan. 1993 to

Kil Hyun Cho; Jun Yong Jung; Jin Ho Song; Jong Cheol Ryu; Doo Il Kim; Dong Soo Kim

238

Germ Cell Intercellular Bridges  

PubMed Central

Stable intercellular bridges are a conserved feature of gametogenesis in multicellular animals observed more than 100 years ago, but their function was unknown. Many of the components necessary for this structure have been identified through the study of cytokinesis in Drosophila; however, mammalian intercellular bridges have distinct properties from those of insects. Mammalian germ cell intercellular bridges are composed of general cytokinesis components with additional germ cell–specific factors including TEX14. TEX14 is an inactive kinase essential for the maintenance of stable intercellular bridges in gametes of both sexes but whose loss specifically impairs male meiosis. TEX14 acts to impede the terminal steps of abscission by competing for essential component CEP55, blocking its interaction in nongerm cells with ALIX and TSG101. Additionally, TEX14-interacting protein RBM44, whose localization in stabile intercellular bridges is limited to pachytene and secondary spermatocytes, may participate in processes such as RNA transport but is nonessential to the maintenance of intercellular bridge stability.

Greenbaum, Michael P.; Iwamori, Tokuko; Buchold, Gregory M.; Matzuk, Martin M.

2011-01-01

239

A high-efficiency soft-switched AC\\/DC converter with current-doubler synchronous rectification  

Microsoft Academic Search

An improved ac\\/dc converter based on asymmetrical half-bridge topology is proposed in this paper. To substantially enhance the efficiency for low-voltage\\/high-current output applications, a current-doubler synchronous rectifier is combined with a modified asymmetrical half-bridge converter that retains the inherent zero-voltage-switching property. The power losses in the secondary rectification stage and the primary switches can be significantly reduced. The proposed architecture

Huang-Jen Chiu; Li-Wei Lin

2005-01-01

240

Conversion of midbodies into germ cell intercellular bridges  

PubMed Central

Whereas somatic cell cytokinesis resolves with abscission of the midbody, resulting in independent daughter cells, germ cell cytokinesis concludes with the formation of a stable intercellular bridge interconnecting daughter cells in a syncytium. While many proteins essential for abscission have been discovered, until recently, no proteins essential for mammalian germ cell intercellular bridge formation have been identified. Using TEX14 as a marker for the germ cell intercellular bridge, we show that TEX14 co-localizes with the centralspindlin complex, mitotic kinesin-like protein 1 (MKLP1) and male germ cell Rac GTPase-activating protein (MgcRacGAP), and converts these midbody matrix proteins into stable intercellular bridge components. In contrast, septins (SEPT) 2, 7, and 9 are transitional proteins in the newly forming bridge. In cultured somatic cells, TEX14 can localize to the midbody in the absence of other germ cell specific factors, suggesting that TEX14 serves to bridge the somatic cytokinesis machinery to other germ cell proteins to form a stable intercellular bridge essential for male reproduction.

Greenbaum, Michael P.; Ma, Lang; Matzuk, Martin M.

2009-01-01

241

Multilevel converters-a new breed of power converters  

Microsoft Academic Search

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

Jih-Sheng Lail; Fang Zheng Peng

1995-01-01

242

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

243

Analog to Digital Converter.  

National Technical Information Service (NTIS)

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

B. L. Lewis

1981-01-01

244

Heat flux converter  

Microsoft Academic Search

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

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

1968-01-01

245

How to Convert Temperatures  

NSDL National Science Digital Library

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

2003-05-09

246

Fractional Watt AMTEC Converter  

NASA Astrophysics Data System (ADS)

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

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

2006-01-01

247

Ocean wave energy converter  

Microsoft Academic Search

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

1982-01-01

248

Ocean wave energy converter  

Microsoft Academic Search

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

1987-01-01

249

Converting industrial boilers  

Microsoft Academic Search

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

D. F. Dunphy; V. S. Ramapriya

1981-01-01

250

Converting Bookmobiles to Paperbacks  

ERIC Educational Resources Information Center

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

Little, Paul

1976-01-01

251

Digitise this: converting content  

Microsoft Academic Search

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

Cathie Jilovsky; George Panagiotidis

252

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.

253

The aesthetic composite bridge.  

PubMed

New developments are constantly introduced in the search for the optimal treatment modality to restore a single anterior tooth. The patient attention has shifted to aesthetics of the restoration, biocompatibility of the dental materials utilized, conservative preparation of the teeth to be restored, and the retention of intact adjacent dentition. The learning objective of this article is to review the methods currently utilized and to present a recently introduced treatment modality--the two-component bridge, which combines the strength and resiliency of composite resin with the aesthetic advantages of porcelain. The technology of the material is reviewed, the predominantly lingual tooth preparation procedures are outlined, and the bridge try-in is described. The advantages of the two-component bridge are presented along with the contraindications and suggestions of careful case selection. Three cases with congenitally missing maxillary lateral incisors in youthful patients are presented to supplement the theoretical outline and to describe and illustrate the clinical procedure. PMID:9550061

Feinman, R A

1997-01-01

254

Liquid metal thermal electric converter  

DOEpatents

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

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

1989-01-01

255

Dog Bridge, view of the deck of the bridge and ...  

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

Dog Bridge, view of the deck of the bridge and rails looking from Linden Lane - National Park Seminary, Bounded by Capitol Beltway (I-495), Linden Lane, Woodstove Avenue, & Smith Drive, Silver Spring, Montgomery County, MD

256

Bridg.me  

NSDL National Science Digital Library

What if you could have a conference call that called you? Such a thing is now possible courtesy of Bridg.me. Apparently one of the co-founders of Bridg.me was never on time for meetings and conferences, so this handy website was created to solve the problem. Visitors just need to register online, put a meeting in their Google Calendar, and the conference will call them at the appointed hour and minute. It's quite easy to use and it's compatible with all operating systems.

257

Contribution to the AC-analysis of resonant converters; analysis of the series-parallel resonant converter including effects of parasitics and lossless snubbers for optimized design  

Microsoft Academic Search

A stress analysis is performed based on the complex AC-analysis technique for half-bridge resonant power converters. Selecting the series-parallel topology (LCC) for high-power applications with low output voltage, the ideal and the lossy converter are analyzed in the time domain and evaluated by measurements and in comparison to the simplified analysis to find an optimum operating range and design

N. Frohleke; J. Kunze; A. Fiedler; H. Grotstollen

1992-01-01

258

16. LOG AND PLANK BRIDGE ON ACCESS ROAD NEAR BRIDGE ...  

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

16. LOG AND PLANK BRIDGE ON ACCESS ROAD NEAR BRIDGE SITE; SAME STRUCTURE AS SHOWN IN PHOTO #12. ZION NP NEGATIVE NO. 967 ZIO. - Zion-Mount Carmel Highway, Virgin River Bridge, Spanning North Fork of Virgin River on Zion-Mount Carmel Highway, Springdale, Washington County, UT

259

1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT ...  

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

1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT LEFT AND THE ROCK CREEK AND POTOMAC PARKWAY RAMP AT RIGHT. VIEW TAKEN FROM THE REAR OF THE LINCOLN MEMORIAL. - Arlington Memorial Bridge, Boundary Channel Extension, Spanning Mount Vernon Memorial Highway & Boundary Channel, Washington, District of Columbia, DC

260

Retrofitted Bridge Fragility Analysis for Typical Classes of Multispan Bridges  

Microsoft Academic Search

Retrofitted bridge fragility curves provide a powerful tool for assessing the effect of retrofit measures on the seismic performance of different bridge types under a range of loading levels. Traditional methods for retrofit assessment typically evaluate the effectiveness of retrofit based on the performance of individual components. However, the use of fragility curves for retrofitted bridges has the ability to

Jamie E. Padgett; Reginald DesRoches

2009-01-01

261

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

262

Bridge Types: Tensile & Compressive Forces  

NSDL National Science Digital Library

Students explore how tension and compression forces act on three different bridge types. Using sponges, cardboard and string, they create models of beam, arch and suspension bridges and apply forces to understand how they disperse or transfer these loads.

Integrated Teaching And Learning Program

263

Energy Harvesting on Highway Bridges.  

National Technical Information Service (NTIS)

This project is investigating the potential for generating electrical power from the vibrations of a bridge due to large vehicles. It utilizes state-of-the-art technology and interdisciplinary expertise in solid-state electronics and bridge engineering to...

J. Nolan J. D. Baldwin L. Holliday S. Roswurm

2011-01-01

264

Bridge Design, Testing, and Evaluation.  

National Technical Information Service (NTIS)

The 16 papers in this report deal with the following areas: analysis of a horizontally curved bridge through a geometric structural model; (abridgment) thermal stresses and deformations in nonprismatic indeterminate composite bridges; (abridgment) thermal...

1976-01-01

265

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

266

An improved ZVZCS PWM FB DC\\/DC converter using energy recovery snubber  

Microsoft Academic Search

The conventional high frequency phase-shifted full-bridge DC\\/DC power converter has a disadvantage that a circulating current flows through the transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free-type high-frequency ZVZCS phase-shifted full bridge

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

1997-01-01

267

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

Microsoft Academic Search

A full bridge DC-DC power 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% efficiency

Keming Chen; Thomas A. Stuart

1993-01-01

268

A 1.6 kW, 110 kHz DC-DC converter optimized for IGBTs  

Microsoft Academic Search

A full-bridge DC-DC converter using zero-current and zero-voltage switching techniques 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% efficiency

Keming Chen; Thomas A. Stuart

1991-01-01

269

High Input Voltage Step-Down DC-DC Converters for Integration in a Low Voltage CMOS Process  

Microsoft Academic Search

A cascode bridge circuit for monolithic switching DC- DC converters operating at high input voltages is pro- posed in this paper. The proposed circuit can also be used as an I\\/O buffer to interface circuits operating at signifi- cantly different voltages. The circuit technique permits the full integration of the active and passive devices of a switching DC-DC converter with

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

2004-01-01

270

Parametric energy converter  

SciTech Connect

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

Johnson, R.N.

1981-10-20

271

Bridging The Resource Gap.  

National Technical Information Service (NTIS)

With the Department of Defense under the scrutiny of the American public and the media always nearby, how should the military best prepare the leaders of tomorrow to cope with change during fiscally austere times. In my opinion, the key to bridging what I...

A. H. Villarreal

1995-01-01

272

Bridging the Gaps.  

ERIC Educational Resources Information Center

Discusses a model water quality monitoring project, Project Bridge, established to train minority girls about to enter eighth grade in scientific procedures followed by hands-on experimentation. Students spent a week monitoring water in an urban stream and analyzing results. (LZ)

Netzer, Greg

1995-01-01

273

Design Squad: Suspension Bridge  

NSDL National Science Digital Library

In this video segment adapted from Design Squad—a PBS TV series featuring high school contestants tackling engineering challenges—students employ the concepts of tension and compression to build a suspension bridge without the aid of power tools.

Foundation, Wgbh E.

2007-08-09

274

Design Squad: Truss Bridge  

NSDL National Science Digital Library

In this video segment adapted from Design Squad—a PBS TV series featuring high school contestants tackling engineering challenges—students employ the concepts of tension and compression as they build a truss bridge without the aid of power tools.

Foundation, Wgbh E.

2007-08-09

275

Virtual Bridge Design  

ERIC Educational Resources Information Center

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…

Bisogno, Janet; JeanPierre, Bobby

2008-01-01

276

Bridging the Gap.  

ERIC Educational Resources Information Center

Describes interdisciplinary activities with real-world applications ranging from science to mathematics to technology. Cites the study and construction of model bridges as a way for students to learn about engineering concepts and some of their relationships. States that the exercise enhanced teacher cooperation between the different fields. (RT)

Kroto, Joseph J.

1988-01-01

277

Bridge Deck Drainage Guidelines.  

National Technical Information Service (NTIS)

The document presents criteria to determine if bridge drainage scuppers and drains are required. A design nomograph allows a rapid decision to be made. A key variable, design rain intensity, is analyzed: the rational method is reviewed and new methods for...

G. K. Young J. Phillippe S. J. Bellomo J. Normann W. E. Hughes

1986-01-01

278

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

279

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

280

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

281

Quantum Bidding in Bridge  

NASA Astrophysics Data System (ADS)

Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been 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 an advantage in a 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 a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate 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 game, which is equivalent to a 2?1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.

Muhammad, Sadiq; Tavakoli, Armin; Kurant, Maciej; Paw?owski, Marcin; ?ukowski, Marek; Bourennane, Mohamed

2014-04-01

282

Semiconductor Bridge Cable Tests.  

National Technical Information Service (NTIS)

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 (FS). A series of tests were performed to identify smaller, lighter cables for firing single and multip...

T. L. King

2002-01-01

283

Semiconductor Bridge Cable Test  

Microsoft Academic Search

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

TONY L

2002-01-01

284

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

285

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

286

Jointless Bridge Decks.  

National Technical Information Service (NTIS)

The major focus of this research was to validate the concept of connecting two adjacent simple-span girders with a link slab to form a jointless bridge deck so as to eliminate the standard deck joint between the girders. Laboratory tests were conducted on...

P. Zia A. Caner A. K. El-Safty

1995-01-01

287

Tech Prep Bridge Programs.  

ERIC Educational Resources Information Center

Although tech prep is still in its infancy in Georgia, increasing numbers of students are entering technical institutes after having completed the secondary-level component of tech prep programs. Georgia's technical institutes must begin the process of developing bridge programs to help adult students with no tech prep experience develop academic…

Gohdes, William

1995-01-01

288

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

289

JHU Bridge Designer  

NSDL National Science Digital Library

The Bridge Designer is a web-based program that allows the user to design and analyze 2-Dimensional statically determinate trusses. The user can specify support types (fixed or rolling) and locations, as well as the locations of various truss nodes and members.

Karweit, Michael

290

Tension roofs and bridges  

Microsoft Academic Search

The term ‘Tension Structures’ is commonly used for those structures wherein one or more primary load bearing elements are in tension. Such structures include membrane roofs, cable roofs, cable bridges, guyed masts or towers, cooling towers though some of these are less common. The tension elements are strands, ropes or membranes, which have to combine with structural elements carrying compression,

P Krishna

2001-01-01

291

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.

292

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

293

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

294

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

295

Construction of an Experimental Segmental Bridge.  

National Technical Information Service (NTIS)

Concrete segmental bridge construction seems to offer many advantages over other types of bridge construction both in bridge replacement programs and in new bridge programs. This report discusses the construction process of the experimental segmental brid...

R. M. McClure H. R. Thomas J. E. Kehler

1980-01-01

296

Standard Plans for Southern Pine Bridges.  

National Technical Information Service (NTIS)

This publication contains standardized designs and details for three timber bridge superstructure types, including stress-laminated sawn lumber bridges, stress laminated glued laminated timber (glulam) bridges, and longitudinal sawn lumber stringer bridge...

M. Triche M. A. Ritter P. D. Hilbrich Lee

1995-01-01

297

Wikipedia: Cable-Stayed Bridge  

NSDL National Science Digital Library

This site contains a description of cable-stayed bridges and their advantages, illustrated by numerous photographs. It has a thorough explanation of the differences between the cable-stayed bridge and the suspension bridge, both in design and in the manner of construction. Variations and related types are shown, and links are included to a large number of examples.

2006-07-01

298

Fibre reinforced composite dental bridge  

Microsoft Academic Search

This experimental investigation aims at revealing the mechanical behaviour and failure pattern of direct fibre-reinforced resin-bonded dental bridge with various designs. To evaluate the overall effects of some newly developed dental materials, in the experiment, genuine composite dental bridge specimens are prepared and tested. The ultimate load, stiffness and mode at the failure of the bridges are measured and compared

W. Li; M. V. Swain; Q. Li; J. Ironside; G. P. Steven

2004-01-01

299

Cracks in Concrete Bridge Decks.  

National Technical Information Service (NTIS)

A study of cracks in bridge decks as reported in the literature and observed in NSW shows that certain types of cracks are predominant in particular bridge types. Cracks in composite bridges and in cast-in-place kerbs and cantilever deck slabs are shown t...

D. Campbell-Allen B. Lau

1978-01-01

300

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

301

A video assisted approach for structural health monitoring of highway bridges under normal traffic  

NASA Astrophysics Data System (ADS)

Structural condition assessment of highway bridges is traditionally performed by visual inspections or nondestructive evaluation techniques, which are either slow, unreliable or detects only local flaws. Instrumentation of bridges with accelerometers and other sensors, however, can provide real-time data useful for monitoring the global structural conditions of the bridges due to ambient and forced excitations. This paper reports a video-assisted approach for structural health monitoring of highway bridges, with results from field tests and subsequent offline parameter identification. The field tests were performed on a short-span instrumented bridge. Videos of vehicles passing by were captured, synchronized with data recordings from the accelerometers. For short-span highway bridges, vibration is predominantly due to traffic excitation. A stochastic model of traffic excitation on bridges is developed assuming that vehicles traversing a bridge (modeled as an elastic beam) form a sequence of Poisson process moving loads and that the contact force of a vehicle on the bridge deck can be converted to equivalent dynamic loads at the nodes of the beam elements. Basic information of vehicle types, arrival times and speeds are extracted from video images to develop a physics-based simulation model of the traffic excitation. This modeling approach aims at circumventing a difficulty in the system identification of bridge structural parameters. Current practice of system identification of bridge parameters is often based on the measured response (or system output) only, and knowledge of the input (traffic excitation) is either unknown or assumed, making it difficult to obtain an accurate assessment of the state of the bridge structures. Our model reveals that traffic excitation on bridges is spatially correlated, an important feature that is usually incorrectly ignored in most output-only methods. A recursive Bayesian filtering is formulated to monitor the evolution of the state of the bridge. The effectiveness and viability of this video-assisted approach are demonstrated by the field results.

Chen, Yangbo; Tan, Chin-An; Feng, Maria Q.; Fukuda, Yoshio

2006-04-01

302

A Novel T-Connected Autotransformer Based 30- Pulse AC-DC Converter for Power Quality Improvement  

Microsoft Academic Search

This paper presents the design and analysis of a novel T-connected autotransformer based 30-phase ac-dc converter which supplies direct torque controlled induction motor drives (DTCIMD's) in order to have better power quality conditions at the point of common coupling. The proposed converter output voltage is accomplished via three paralleled 10-pulse ac-dc converters each of them consisting of 5-phase diode bridge

Rohollah Abdollahi

2012-01-01

303

Open-loop approach for control of multi-terminal DC systems based on modular multilevel converters  

Microsoft Academic Search

In this paper a multi-terminal direct current (MTDC) system with modular multilevel converters (M2Cs) is suggested. An open loop control method is used for the control of the converters. Each converter is modeled with 36 sub-modules per arm with a total of 216 sub-modules consisting of half bridges. Power-synchronization control is used instead of a phase-locked loop (PLL) for synchronization.

Arif Haider; Noman Ahmed; Lennart Angquist; Hans-Peter Nee

2011-01-01

304

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

305

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

306

The convertible flywheel  

NASA Astrophysics Data System (ADS)

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

Ginsburg, B. R.

307

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

308

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

309

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

310

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

311

Cost of Impressed Current Cathodic Protection for Coastal Oregon Bridges  

SciTech Connect

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 average $14.08/ft2 ($151.47/m2), while zinc anode installation cost an average of $7.13/ft2 ($76.67/m2). Oregon's rugged and beautiful coastline is graced with a series of historical arched bridges designed by Conde B. McCullough. McCullough is the internationally recognized architect who designed many of the Oregon Coast Highway (U.S. 101) bridges in the 1920s and 1930s. Many are listed on the National Historic Register. After the expense ($45m) and public outcry associated with the replacement of the historic Alsea Bay Bridge in Waldport, Oregon, the Oregon Department of Transportation began using impressed current cathodic protection (ICCP) to extend the service life of reinforced concrete bridges. Figure 1 visually illustrates the need for such remediation. It shows exposed rebar from underneath the Brush Creek Bridge, which is very representative of the conditions found underneath many coastal Oregon bridges. Four ICCP projects have been funded, put out for bid, and completed. The four projects, their bid closing dates, and their completion dates are the Cape Creek Bridge (1990- 1992), the Yaquina Bay Bridge south arches (1991-1995), the Depoe Bay Bridge (1993-1997), and the Yaquina Bay Bridge south approach (1995-1997). The Cape Creek, Yaquina Bay, and Depoe Bay Bridges are shown in Figs. 2-4. Other ICCP projects are underway on the Oregon coast. In the ICCP systems, arc-sprayed zinc coatings on the concrete surface are anodes that protect the steel rebar. Accelerated laboratory studies at the Albany Research Center have predicted zinc anode service lives of approximately 27 years based on long-term bond strength measurements.1-3 Experience in California4 has documented zinc anode service lives of over 11 years. Both indicate a substantial savings in project costs compared to bridge replacement. For example, the replacement cost of the arc-sprayed sections of the three Oregon bridges is estimated to be $57m, while the four ICCP projects on those bridges have cost $20m. (The $45m to replace the Alsea Bay Bridge was more than simply the replacement cost--it included expanding the bridge to four lanes and making the bridge ''ICCP ready'' by ensuring electrically continuous rebar).

Holcomb, Gordon R.; Cryer, Curtis B.

1998-07-01

312

Electrical Actuation Technology Bridging  

NASA Technical Reports Server (NTRS)

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 (compiler); Sharkey, John (compiler)

1993-01-01

313

Bridging semiconductor and magnetism  

NASA Astrophysics Data System (ADS)

Carrier-induced ferromagnetism and its manipulation in Mn-doped III-V semiconductors, such as (In,Mn)As and (Ga,Mn)As, offer a wide variety of phenomena that originate from the interplay between magnetism and semiconducting properties, forming a bridge between semiconductor and magnetism. A review is given on the electrical manipulation of magnetism, its understanding, and potential applications both from the physics point of view and from the technological point of view. The electric-field study on magnetism is now being extended to magnetic metals, leading to an energy efficient way of magnetization reversal important for future semiconductor integrated circuit technology, yet another route to bridge semiconductor and magnetism in a fruitful way.

Ohno, H.

2013-04-01

314

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

315

A Transformerless Medium-Voltage STATCOM Topology Based on Extended Modular Multilevel Converters  

Microsoft Academic Search

A new transformerless four-leg topology is suggested for shunt compensation, the modular multilevel converters (MMC) based on the half-bridge converters, to achieve higher perfor- mance as a STATCOM in a distorted and unbalanced medium- voltage large-current (MV-LC) system. Further, an extended MMC (EMMC) is proposed in order to manage more accurate compen- sation for high-power applications. Both proposals can be

M. Tavakoli Bina

2011-01-01

316

A new resonant active clamping technique for bi-directional converters in HEVs  

Microsoft Academic Search

In this paper a resonant active clamp circuit is presented, addressing the efficient optimization of a bidirectional DCDC converter for hybrid electric vehicles applications. The converter structure is based on a combination of two dc\\/dc topologies connected through a high frequency transformer, a full-bridge stage modulated in phase shift for step-down operations and a current-source push-pull stage used as step-up.

Mario Cacciato; A. Consoli; V. Crisafulli; G. Vitale; N. Abbate

2010-01-01

317

Non-Dissipative Snubber for Rectifying Diodes in a High-Power DC-DC Converter  

NASA Astrophysics Data System (ADS)

In a high output current DC-DC converter, most power dissipation comes from rectifying diodes. In this paper, a novel non-dissipative snubber is proposed for the rectifying diodes to reduce the power dissipation of the rectifying circuit. This snubber is applied to the center-tapped rectifying circuit in a full-bridge DC-DC converter. As a result, the efficiency has been improved to 91% on the prototype of 12V/80A output.

Hirokawa, Masahiko; Ninomiya, Tamotsu

318

Power Quality Improvements Using Delta-Polygon Connected Autotransformer Based Nine Phase AC-DC Converter  

Microsoft Academic Search

This paper deals with a novel delta-polygon connected autotransformer based improved power quality nine-phase ac-dc converter feeding vector controlled induction motor drives (VCIMD's). The design of the proposed autotransformer is presented along with the necessary modifications required for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed ac-dc converter is found capable

B. Singh; V. Garg; G. Bhuvaneswari

2006-01-01

319

Effects of the saturable resonant inductor on the rectifying diode reverse recovery of ZVS converters  

Microsoft Academic Search

This paper presents an analysis of the effects of the saturable resonant inductor on the rectifying diode reverse recovery of zero-voltage-switching quasi-resonant power converters, and full-bridge zero-voltage-switched PWM power converter. The design of a clamping circuit considering a saturable resonant inductor is presented and compared with the design of a clamping circuit with a linear resonant inductor. A diode model

R. N. do Prado

1994-01-01

320

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

321

Bidirectional buck boost converter  

DOEpatents

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

Esser, A.A.M.

1998-03-31

322

Grid interconnection for variable-speed wind farm with multi-level inverter  

Microsoft Academic Search

This paper presents design, modeling, and control of grid interconnection for a wind farm with round-rotor synchronous generators. The grid interconnection proposed in this paper supports the variable-speed wind turbine concept with the three-phase diode bridge as a front-end rectifier. The wind energy resources and the utility grid are isolated by intermediate fly-back converters. The grid interface multi-level inverter with

Siriya Skolthanarat; Virgilio Centeno

2008-01-01

323

A waveguide-typed plasmonic mode converter.  

PubMed

Waveguide-typed plasmonic mode converters (WPMCs) at a wavelength of 1.55 ?m are presented. The WPMC is composed of an insulator-metal-insulator waveguide (IMI-W), a 1st reversely tapered insulator-metal-insulator-metal-insulator waveguide (RT-IMIMI-W), an insulator-metal-insulator-metal-insulator waveguide (IMIMI-W), a 2nd RT-IMIMI-W with lateral silver mirrors (LSMs), and a metal-insulator-metal waveguide (MIM-W) in series. The mode sizes for the IMI-W, IMIMI-W, and MIM-W via the IMIMI-W with LSMs were not only calculated using a finite element method but were also experimentally measured. The input mode size of 10.3 ?m × 10.3 ?m from a polarization-maintaining single-mode fiber was squeezed to the mode size of ~2.9 ?m × 2.9 ?m in measurement by converting an s0 mode to an Sa0 mode via an Ss0 mode. The WPMC may be potentially useful for bridging micro- to nano-plasmonic integrated circuits. PMID:23038504

Park, Hae-Ryeong; Park, Jong-Moon; Kim, Min-Su; Lee, Myung-Hyun

2012-08-13

324

Two new methanol converters  

SciTech Connect

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

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

1988-11-01

325

Converting industrial boilers  

SciTech Connect

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

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

1981-03-01

326

Fluorescent radiation converter  

NASA Technical Reports Server (NTRS)

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

Viehmann, W. (inventor)

1981-01-01

327

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

328

Unity power factor converter  

NASA Technical Reports Server (NTRS)

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

Wester, Gene W. (Inventor)

1980-01-01

329

Foundation Depth for Bridge Piers  

NASA Astrophysics Data System (ADS)

The safety of bridge piers built in rivers having the bed is one of the prime aspects in the study of scouring process around bridge piers. The stability of bridge piers depends on the depth of foundation provided below maximum scour level. The stability analysis of bridge piers is carried based on moment of forces acting on the caisson pier when the pier slides and tilts slightly in downstream from its position. The experiments are conducted for three pier shapes on two sediment beds and for different flow conditions. The curves indicating the stability limits are compared with Lacey's recommendations which are used in present day practice in India. The analysis presented here indicates that the Lacey's recommendation for railway bridges is safe and for some cases of the road bridges depends on grip length, angle of tilt and weight of caisson.

Veerappadevaru, G.; Gangadharaiah, T.; Jagadeesh, T. R.

2013-09-01

330

EARTHQUAKE RESPONSE OF SUSPENSION BRIDGES  

Microsoft Academic Search

Suspension bridges represent critical nodes of major transportation systems. Bridge failure during strong earthquakes poses\\u000a not only a threat of fatalities but causes a substantial interruption of emergency efforts. Although wind induced vibrations\\u000a have historically been the primary concern in the design of suspension bridges, earthquake effects have also gained importance\\u000a in recent decades. This study involves ambient vibration testing

Mustafa Erdik; Nurdan Apayd?n

331

Bridging the Watershed  

NSDL National Science Digital Library

Bridging the Watershed is a partnership between Washington DC area schools and the National Park Service that uses the Potomac River and Chesapeake Bay watersheds as "learning laboratories." The Students section of this site has some great interactive activities that help students learn how to identify plants and ecosystems, determine stream health based on macroinvertebrate identification, and understand the perils of migratory fish. This is a great Web site with a broad range of information suitable to a variety of different age levels and interests, yet with enough detail to make each section stand alone.

332

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

333

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. [CL

334

A Sparse Multilevel Matrix Converter Based on Diode-Clamped Topology  

Microsoft Academic Search

This paper presents a novel sparse matrix converter configuration that needs no bulky energy storage capacitors or inductors, and employs only unidirectional power semiconductor switches. The source side bridge is switched at the line frequency and therefore, this allows the use of the low speed high power rating switches. This feature and the use of diode-clamped multilevel topology at the

S. Ali Khajehoddin; Alireza Bakhshai; Praveen Jain

2007-01-01

335

Influence of the modulation method on the conduction and switching losses of a PWM converter system  

Microsoft Academic Search

The dependency of the conduction losses of a bridge leg of a PWM power converter system with a high pulse rate on the shape of the phase modulation functions is explored. This is done for modulation methods which are optimized with respect to minimum harmonic current RMS values. The results are compared to the results gained for simple sinusoidal modulation.

JOHANN W. KOLAR; HANS ERTL; FRANZ C. ZACH

1990-01-01

336

A parallel loaded DC\\/DC resonant converter with a new power and control circuit  

Microsoft Academic Search

In this paper a new power circuit and control scheme for a parallel loaded DC\\/DC converter with a smaller number of switching devices compared with analogue circuits is presented. Return of energy to the source, omitting of output rectifier bridge and simple control circuit for regulating of the output DC voltage are some of the advantages of the proposed power

S. H. Hosseini; M. Tarafdar Hague

2000-01-01

337

DC power transmission system of voltage source converter using pulse-interleaving auxiliary circuit  

US Patent & Trademark Office Database

A DC power transmission system of a voltage source converter using a pulse-interleaving auxiliary circuit is disclosed. The converter system comprises an IGBT converter for converting an AC power to a DC power or the DC power to the AC power; an open Y-Y transformer and a Y-.DELTA. transformer for stepping up or stepping down the AC power having a predetermined magnitude; a capacitor for dividing a DC voltage; and a DC Auxiliary circuit composed of a normal transformer and half-bridge for overlapping a pulse type input voltage to increase the number of pulses of an output waveform. In using a DC auxiliary circuit composed of normal transformer and 3-level half-bridge to increase the number of pulses of the output waveform by superposing the voltage in the form of the pulse, a normal transformer may be used instead of the tapped transformer to reduce the size thereof and to obtain an accurate transformer ratio, and a 3-level half-bridge may be used instead of the H-bridge to reduce the switching loss.

2009-03-03

338

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

Microsoft Academic Search

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

Ashish Shrivastava; Bhim Singh

2010-01-01

339

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

Microsoft Academic Search

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

Richard Morrison; Michael G. Egan

2000-01-01

340

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

341

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

342

75 FR 62181 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation  

Federal Register 2010, 2011, 2012, 2013

...Annual Materials Report on New Bridge Construction and Bridge Rehabilitation AGENCY...Federal Register a report describing construction materials used in new Federal-aid bridge construction and bridge rehabilitation...

2010-10-07

343

77 FR 53251 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation  

Federal Register 2010, 2011, 2012, 2013

...Annual Materials Report on New Bridge Construction and Bridge Rehabilitation AGENCY...Federal Register a report describing construction materials used in new Federal-aid bridge construction and bridge rehabilitation...

2012-08-31

344

76 FR 55160 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation  

Federal Register 2010, 2011, 2012, 2013

...Annual Materials Report on New Bridge Construction and Bridge Rehabilitation AGENCY...Federal Register a report describing construction materials used in new Federal-aid bridge construction and bridge rehabilitation...

2011-09-06

345

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

346

Thermionic Converter Life and Repeatability Investigation.  

National Technical Information Service (NTIS)

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

C. Z. Kamien L. van Someren

1966-01-01

347

3. HONEYWELL STREET BRIDGE AND ELEVATED SUBWAY BRIDGE CROSSING SUNNYSIDE ...  

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

3. HONEYWELL STREET BRIDGE AND ELEVATED SUBWAY BRIDGE CROSSING SUNNYSIDE YARDS. LONG ISLAND CITY, QUEENS CO., NY. Sec. 1411, MP 3.55. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

348

5. North side of throughtruss bridge over railroad tracks (bridge ...  

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

5. North side of through-truss bridge over railroad tracks (bridge #U182512605). View to southwest. - South Omaha Union Stock Yards, "O" Street Viaduct, "O" Street Spanning Hog Pens; South Omaha Terminal Railway Company Tracks & Union Pacific Railroad Tracks, Omaha, Douglas County, NE

349

Association for Bridge Construction and Design: Bridge Design Tips  

NSDL National Science Digital Library

The Association for Bridge Construction and Design was formed in response to "the bridge crisis" which leaves "only an extremely small percentage of bridges throughout the nation" receiving the attention they need. The goal of the Association is to educate bridge designers, constructors, federal, state, and local officials, as well as the general public in the vital role of safe bridges in our society; to improve the science of bridge design, construction and reconstruction through a professional forum; to provide technical information and assistance; and to educate and encourage public and private authorities to use new and improved techniques for testing and reconstruction. This section of the website provides a basic overview of bridge construction along with related drawings and pictures. By reading through the text and following the links, visitors are taken to a section that discusses ways to calculate the forces in your trusses and then use Java program to design trusses. Links to related articles and websites are available for further reading on the subject of bridge design. Although the website has not been updated recently, the resources are still relevant.

350

25. White Plains Road Bridge in foreground; Unionport Road Bridge ...  

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

25. White Plains Road Bridge in foreground; Unionport Road Bridge in background. Van Nest, Bronx Co., NY. Sec. 4207, MP 12.75./78. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY

351

Four quadrant operating Luo-converters  

Microsoft Academic Search

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

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

2000-01-01

352

Photovoltaic energy converters  

NASA Astrophysics Data System (ADS)

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

Bloss, W. H.

353

Wind power converter  

SciTech Connect

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

Tornquist, A.

1982-12-21

354

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

355

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.

356

NOVEL topology of traction converter with single phase Matrix converter  

Microsoft Academic Search

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

PITTERMANN Martin; DRÁBEK Pavel; CÉDL Marek

2009-01-01

357

High-frequency resonant transistor dc-dc converters  

NASA Astrophysics Data System (ADS)

The design of a transistor dc-dc resonant converter operating at 200-300 kHz is presented, and the operation of a 500-W breadboard version is reported. Several configurations of both voltage-input and current-input type are described and illustrated with circuit diagrams and waveforms, and a full-bridge voltage-input resonant inverter using gate turnoff devices is analyzed in detail, using a piecewise linear approach to obtain design curves. The performance of the breadboard voltage-input half bridge using FET power switches is shown in graphs, demonstrating the low switching losses and transistor stresses achieved by lossless-snubber design. It is predicted that similar designs using bipolar transistors or GTOs can attain energy efficiencies greater than 90 percent. Applications to switching power supplies and battery chargers are suggested.

Steigerwald, R. L.

1984-05-01

358

Multifunctional interleaved boost converter for PV systems  

Microsoft Academic Search

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

I. Sefa; S. O?zdemir

2010-01-01

359

Buck-boost integrated forward converter  

Microsoft Academic Search

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

Z. Nie; A. Emadi

2005-01-01

360

Evaluation of the Bridge Program.  

ERIC Educational Resources Information Center

This evaluation of the 1989-90 BRIDGE Project, a dropout prevention program in Hartford (Connecticut), found that grade 9 students felt a heightened sense of control over their lives after one year in the program. BRIDGE is a multifaceted program that focuses on reducing the disengagement of at-risk students facing the critical transition from…

Words + Numbers, Torrington, CT.

361

Fatigue of steel bridge infrastructure  

Microsoft Academic Search

This paper presents an overview of the development of fatigue design provisions and detailing for steel bridge structures. The historical performance of welded steel bridges in the USA is reviewed with focus on fatigue cracking at cover plate and similar attachment details, as well as distortion induced cracking at web gaps. The role of materials including modern high performance steels

J. W. Fisher; S. Roy

2011-01-01

362

The Bridge of Mandolin County  

Microsoft Academic Search

The Bridge of Mandolin County is a case designed to teach the general chemistry principles of molar mass, ions and aqueous reactions, solubility rules, and inorganic nomenclature. Through the instructor-facilitated class discussion, students consider the options before the Mandolin Town Council regarding deicing the newly constructed bridge connecting Mandolin with a large nearby city. The students must decipher contradictory claims

Juliette M. Lantz; Jenny E. Feindt; Eric P. B. Lewellyn; Mary M. Walczak

1999-01-01

363

Seismic Isolation of Highway Bridges.  

National Technical Information Service (NTIS)

More than 200 bridges have been designed or retrofitted in the United States using seismic isolation in the last 20 years, and more than a thousand bridges around the world now use this cost- effective technique for seismic protection. Intended to supplem...

2006-01-01

364

Life Cycle Cost of Bridges.  

National Technical Information Service (NTIS)

This is a continuation of the 2004 project to use historical cost data from a variety of geographically distributed bridges of different structural designs to (a) formulate a cost model for bridge life cycle cost, (b) assess the impact of deferred mainten...

R. Krizek

2009-01-01

365

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

366

Prioritization of Bridges for Seismic Retrofitting.  

National Technical Information Service (NTIS)

This report presents a prioritization method developed for seismic retrofitting of bridges. The method is used to identify bridges that are in most need of retrofitting and rank order these bridges based on the vulnerability and importance criteria. Vulne...

N. Basoez A. S. Kiremidjian

1995-01-01

367

Developing Deterioration Models for Nebraska Bridges.  

National Technical Information Service (NTIS)

Nebraska Bridge Management System (NBMS) was developed in 1999 to assist in optimizing budget allocation for the maintenance, rehabilitation and replacement needs of highway bridges. This requires the prediction of bridge deterioration to calculate life-c...

A. Hatami G. Morcous

2011-01-01

368

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

369

Bandwidth considerations for multilevel converters  

Microsoft Academic Search

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

Geoff Walker; Gerard Ledwich

1999-01-01

370

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

371

Thyristor converter simulation and analysis  

SciTech Connect

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

Zhang, S.Y.

1991-01-01

372

Magnetic integration for interleaved converters  

Microsoft Academic Search

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

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

2003-01-01

373

The Angiotensin I Converting Enzyme.  

National Technical Information Service (NTIS)

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

E. G. Erdos

1977-01-01

374

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

375

Resonant AC to AC converter  

Microsoft Academic Search

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

Vineeta Agarwal; Sachin Nema

2005-01-01

376

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

377

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

378

A bridge between cultures  

NASA Astrophysics Data System (ADS)

Journalists who report on scientific discoveries and the scientists who make them are, in many cases, separated by a Grand Canyon-sized gap. A recent U.S. survey revealed that journalists believe that scientists' jargon prevents effective communication. Scientists polled in the same survey, conducted by Today Show host Jim Hartz and NASA scientist Rick Chappell, said that journalists need to do a better job of verifying facts and interpreting scientific results.Panelists representing the scientific and media communities will discuss ways to bridge that gap during the “Science and the Media” episode of Freedom Speaks, to be aired by Public Broadcasting Stations in May and June (check your local listings).

Friebele, Elaine

379

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.

380

Inverse dual converter (IDC) for high power dc-dc applications  

NASA Astrophysics Data System (ADS)

The inverse dual converter (IDC), suitable for high-power dc-dc conversion applications, is presented. The IDC is a voltage source converter with an ac link and has been derived from an inductor converter bridge. This capacitor commutated converter is capable of continuous voltage step-up or step-down control over a wide range without the need of a transformer. In addition to high-frequency switching the converter is characterized by soft switching techniques, reducing constraints on the ratings of the switches. The average model developed with the help of gyrator theory provides sufficient information for control strategies and design considerations. The results of gyrator modeling and computer simulation are compared with experimental results obtained from a prototype IDC.

Ehsani, M.; Husain, I.; Bilgic, M. O.

381

Construction Technologies: Construct the Strongest Bridge  

NSDL National Science Digital Library

Learners work in pairs to create three simple types of bridges, a beam bridge, an arch bridge, and a suspension bridge. They will observe how the bridges work under load and discover why engineers use different types of bridges for different places. Learners are introduced to the parts needed to build a bridge, and what they are for. Resource contains detailed diagrams and photos to assist in bridge building. Investigating questions allow learners to discuss the activity and apply their understanding to their world. Activity time can be split across multiple meetings.

Trahan-Liptak, Joy

2005-01-01

382

Minimizing the current harmonics RMS value of three-phase PWM converter systems by optimal and suboptimal transition between continuous and discontinuous modulation  

Microsoft Academic Search

A given converter voltage space vector can be realized by a three-phase PWM converter system by switching only two bridge legs. There, the third phase is clamped to the positive or negative DC link voltage. This method is called discontinuous modulation, due to the discontinuous shape of the generating phase modulation functions. As a closer analysis shows, the discontinuous method

JOHANN W. KOLAR; HANS ERTL; FRANZ C. ZACH

1991-01-01

383

High frequency resonant MOS-FET dc-dc converter  

NASA Astrophysics Data System (ADS)

The authors explain the operation of a 100-W half-bridge resonant dc-dc converter, the method of determining the LC constants, and the condition of gate drive for achieving no-loss switching. Since the circuit operation is of a zero-volt-switching type, the switching loss at turn-off as well as turn-on can be zeroed by strengthening the gate drive circuit. It is confirmed that the LC constants can be determined by using a simple circuit model, and that setting a low resonant capacitor voltage is effective for reducing the main circuit loss. The characteristics of some dc-dc converters trial-manufactured on the basis of these results are shown.

Karube, K.; Nomura, T.; Nakano, T.

384

A phase-disposition PWM method for DC voltage balance in cascaded H-Bridge rectifier  

Microsoft Academic Search

In this paper, a novel control scheme for cascaded H-Bridge rectifier (CHBR), which can be used as the primary end of high voltage high power multilevel converters, is presented. The controller is similar with the one for single phase rectifier. To improve the performance of the controller, notch filter and proportion resonance (PR) controller are employed and the discrete methods

Tao Xinghua; Li Yongdong; Sun Min

2010-01-01

385

Switched-capacitor DC-DC converters  

Microsoft Academic Search

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

K. Kuwabara; E. Hiyachika

1988-01-01

386

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

387

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

388

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.

1998-07-01

389

High-temperature solar converter  

NASA Technical Reports Server (NTRS)

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

Ascher, G.

1978-01-01

390

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

391

Method for Converting Chrysotile Asbestos.  

National Technical Information Service (NTIS)

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

Y. Harada

1973-01-01

392

Singly bridged calix  

PubMed

Crowned calix[8]arenes are obtained by direct alkylation of p-tert-butylcalix[8]arene (1) with poly(ethylene glycol) ditosylates in the presence of various bases. K2CO3 promotes the preferential formation of 1,3-calix[8]crowns. Cs2CO3 mainly gives the 1,5-isomers, which are selectively obtained in high yields when shorter chains are used (1,5-crown-2, 88%; 1,5-crown-3, 78%). NaH affords the 1,4-isomers in yields up to 46%, often as the sole crown derivative, besides unreacted 1. 1,2-Calix[8]crowns are also obtained in appreciable amount in some instances. The observed regioselectivity is rationalized in terms of preferential formation of specific anions in dependence of the base strength. Dynamic NMR and modeling studies prove that the polyether chain, depending on its bridging mode, may significantly reduce the available space for the through the annulus passages leading to derivatives conformationally blocked (on the NMR time scale). PMID:10993339

Geraci; Piattelli; Chessari; Neri

2000-08-25

393

An Alternative to Bridge Painting.  

National Technical Information Service (NTIS)

A novel approach to the protection of the structural steelwork of composite bridges is proposed by physically changing the environment to which the steelwork is exposed. Clean steel does not corrode at relative humidities up to 99 percent if environmental...

R. R. Bishop M. A. Winnett

1980-01-01

394

Semiconductor bridge ignited gas generator.  

National Technical Information Service (NTIS)

Compact, lightweight, self-contained gas generator systems are required for a variety of inflation or deployment applications. We designed a generic gas generator employing a semiconductor bridge, SCB, igniter to evaluate the characteristics of the black ...

M. C. Grubelich R. W. Bickes

1992-01-01

395

Resistance Bridge Transducer Conditioning Circuit.  

National Technical Information Service (NTIS)

The patent application relates to a conditioning circuit for a resistance bridge transducer that includes output signal amplification, a voltage regulated DC power source for transducer excitation and a calibration select circuit for selectively inserting...

D. J. Ray

1976-01-01

396

Radiation tolerant power converter controls  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

397

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

398

Transformerless dc-Isolated Converter  

NASA Technical Reports Server (NTRS)

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

Rippel, Wally E.

1987-01-01

399

Washed Out Bridge, Snake Creek Near Whitesburg  

USGS Multimedia Gallery

Tributary to Snake Creek, near Whitesburg, Georgia, showing a washed out bridge. When bridges such as this one collapse during a flood, it is rarely the pressure of the rushing water against the bridge that causes the bridge to fail. Rather, the rushing water erodes the ground underneath and surroun...

2009-10-01

400

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.

401

Feedback bridging fault detection using current monitoring  

Microsoft Academic Search

Feedback bridging faults in CMOS circuits are difficult to detect by monitoring logic values. The authors study the possibility of detecting feedback bridging faults by using current monitoring. It is shown that by monitoring current, the feedback bridging faults that cause a metastable state can be detected. Using the same method, the feedback bridging faults can also be detected that

D. Lu; C. Q. Tong

1992-01-01

402

User-friendly Indices for Bridge Management  

Microsoft Academic Search

The Road Bureau of the Ministry of Land, Infrastructure and Transport (MLIT) is promoting scientific bridge management to effectively preserve the enormous number of bridges in Japan. In the process of strategic bridge management, it is important to explain the needs for preventive investment or management level of highway bridges using proper indices. The National Institute for Land and Infrastructure

Takashi Tamakoshi; Keita Nakasu; Ryoichi Watanabe

403

Earthquake Response of Suspension Bridges  

NASA Astrophysics Data System (ADS)

Suspension bridges represent critical nodes of major transportation systems. Bridge failure during strong earthquakes poses not only a threat of fatalities but causes a substantial interruption of emergency efforts. Although wind induced vibrations have historically been the primary concern in the design of suspension bridges, earthquake effects have also gained importance in recent decades. This study involves ambient vibration testing and sophisticated three-dimensional dynamic finite element analysis and earthquake performance assessment of Fatih Sultan Mehmet and suspension Bo?aziçi bridges in Istanbul under earthquake excitation. Nonlinear time history analysis of 3D finite-element models of Fatih Sultan Mehmet and Bo?aziçi suspension bridges included initial stresses in the cables, suspenders, and towers in equilibrium under dead load conditions. Multi-support scenario earthquake excitation was applied to the structure. Suspension bridges are complex 3-D structures that can exhibit a large number of closely spaced coupled modes of vibration. The large number of closely spaced modes, spatially different ground motion characteristics, and the potential for nonlinear behaviour complicate the seismic response of suspension bridges. Spatial variation of ground motion exhibits itself with different ground motions at supports due to the wave passage, incoherence and local site effects. The source of nonlinear behaviour is due to geometric nonlinearity and the presence of cables that can only carry tensile forces. The natural frequencies of vibration and the corresponding mode shapes in their dead load and live load configurations are determined. Displacement time histories and stresses at critical points of the bridges are computed and their earthquake performance under the action of scenario earthquake are estimated.

Erdik, Mustafa; Apayd?n, Nurdan

404

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

405

An 18Pulse AC-DC Converter for Power Quality Improvement in Vector Controlled Induction Motor Drives  

Microsoft Academic Search

This paper deals with a novel autotransformer based improved power quality eighteen-pulse ac-dc converter feeding vector controlled induction motor drives (VCIMD's). The design of the proposed autotransformer is presented along with the necessary modifications required for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed ac-dc converter is found capable of improving

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2006-01-01

406

Power-quality improvements in vector-controlled induction motor drive employing pulse multiplication in AC-DC converters  

Microsoft Academic Search

This paper deals with the pulse doubling in a 12-pulse ac-dc converter for improving power quality in vector-controlled induction motor drives (VCIMDs). The design of proposed magnetics shows the flexibility in varying the voltage ratio of the autotransformer for making it suitable for retrofit applications, where presently a six-pulse diode bridge rectifier is being used. The proposed ac-dc converter is

Bhim Singh; G. Bhuvaneswari; Vipin Garg

2006-01-01

407

Fuzzy Logic Speed Control of D.C. Motors Fed by Single-Ended Primary Inductance Converters (SEPIC)  

Microsoft Academic Search

The paper presents a closed loop speed control of a separately excited D.C. motor. The D.C. motor is fed from an A.C. supply through a cascade combination of a diode bridge rectifier and a single-ended primary inductance converter (SEPIC). This converter offers both step-up and step-down characteristics of the motor terminal voltage as well as an approximately sinusoidal supply current

M. M. R. Ahmed; G. A. Putrus

2006-01-01

408

Utilization of three-phase thyristor-controlled AC\\/DC converters for reactive power compensation with minimum losses  

Microsoft Academic Search

This paper presents a new control method for three-phase, thyristor-controlled reactors for reactive power compensation applications. A conventional AC\\/DC, three-phase, phase-controlled, bridge power converter is utilized. A relatively small inductance is used for a discontinuous rated inductor current. This results in reducing the inductor size, cost and loss, and greatly reduces the power converter switching losses. Experimental results are shown

D. A. Deib; H. W. Hill

1995-01-01

409

LCC Resonant Converter Operating under Discontinuous Resonant Current Mode in High Voltage, High Power and High Frequency Applications  

Microsoft Academic Search

The full-bridge series-parallel resonant converters (also known as LCC resonant converters) with capacitive output filter is evaluated in high output voltage (>50 kV), high power (>50 kW) and high frequency (20 kHz) ESP (Electrostatic Precipitator) power supply applications. By using the leakage inductance and the winding capacitance of the transformer as the resonant elements only an additional series resonant capacitor

Jun Liu; Licheng Sheng; Jianjiang Shi; Zhongchao Zhang; Xiangning He

2009-01-01

410

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

411

Structural Health Indices for Steel Truss Bridges  

Microsoft Academic Search

\\u000a Steel bridges represent a significant portion of the nation’s aging bridge inventory. The United States Army’s inventory has\\u000a over two hundred steel bridges that are vital to the operation of nearly every Army Installation. The Army regularly inspects\\u000a their bridges to ensure the continued functionality of the bridges. However, current inspection techniques and schedules may\\u000a not be able to detect

Ryan Kent Giles; Robin Kim; Billie F. Spencer; M. Nathan; Anne M. Newmark; Lawrence A. Bergman; Carol K. Shield; Steven C. Sweeney

412

Development of Inspection Robots for Bridge Cables  

PubMed Central

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.

Kim, Se-Hoon; Lee, Jong-Jae

2013-01-01

413

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

414

Multilevel converters for power system applications.  

National Technical Information Service (NTIS)

Multilevel converters are emerging as a new breed of power converter options for power system applications. These converters are most suitable for high voltage high power applications because they connect devices in series without the need for component m...

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

1995-01-01

415

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

416

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

417

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

418

Development of Wood Bridges: Prospects of Wood in Various Types of Bridges.  

National Technical Information Service (NTIS)

Economics and aesthetics of various types of wood bridges are considered. The main emphasis is focused on light traffic bridges, but some road bridges are examined, as well. Basic assumptions are specified concerning loading, material properties, allowabl...

A. Jutila A. Tesar H. Rautakorpi L. Salokangas P. Haakana R. Maekpuro

1993-01-01

419

PWM Converter Power Density Barriers  

NASA Astrophysics Data System (ADS)

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

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

420

Angiotensin converting enzyme inhibitor therapy.  

PubMed

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

Róna, G

1991-01-01

421

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

422

1. Photocopied January 1973 from the Keystone Bridge Company Album, ...  

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

1. Photocopied January 1973 from the Keystone Bridge Company Album, 1874. THE KEYSTONE BRIDGE COMPANY: LUCY FURNACE. - Baltimore & Ohio Railroad, Parkersburg Bridge, Ohio River, Parkersburg, Wood County, WV

423

Construction Technologies: Create the Strongest Bridge  

NSDL National Science Digital Library

Students work in pairs to create three simple types of model bridges (beam, arch, suspension). They observe quantitatively how the bridges work under load and why engineers use different types of bridges for different places. They also get an idea of the parts needed to build bridges, and their functions. The strength of model bridges is mainly a factor of the quality of materials used, and therefore they do not provide a clear visual representation of tension and compression forces involved. Yet, students are able to see these forces at work in three prototype designs and draw conclusions about their dependence on span, width and supporting structures of the bridge designs.

K-12 Outreach Office,

424

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.

425

Topological constraints on basic PWM converters  

NASA Astrophysics Data System (ADS)

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

Liu, Kwang-Hwa; Lee, Fred C.

426

High-power converters for space applications  

NASA Astrophysics Data System (ADS)

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

Park, J. N.; Cooper, Randy

1991-06-01

427

2.NBT Toll Bridge Puzzle  

NSDL National Science Digital Library

This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: The picture shows islands connected by bridges. To cross a bridge, you must pay a toll in coins. If you start on the island marked in blue with 100 coi...

428

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

429

Converting Work into College Credits  

ERIC Educational Resources Information Center

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

Hoffman, Joseph A.

1976-01-01

430

Charge-pump voltage converter  

DOEpatents

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

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

2009-11-03

431

Converting accounts receivable into cash.  

PubMed

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

Folk, M D; Roest, P R

1995-09-01

432

Hoffman HSPP-1 Solar Converter.  

National Technical Information Service (NTIS)

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

R. W. Witter

1968-01-01

433

Bridges: Chesapeake & Ohio Canal National Monument Historic Structures Report. Part II: Historical Data Section.  

National Technical Information Service (NTIS)

Contents: The Georgetown Bridges 1829-1850; The Georgetown Bridges 1850-1889; Bridges on the Washington Branch; Embankment Bridges; Bridges from College Run to Seneca Aqueduct; Bridges from Seneca Aqueduct to Antietam Aqueduct: Bridges from Antietam Aqued...

1968-01-01

434

Integration of traffic information in the structural health monitoring of highway bridges  

NASA Astrophysics Data System (ADS)

Structural condition assessment of highway bridges is traditionally performed by visual inspections or nondestructive evaluation techniques, which are either slow, unreliable or detects only local flaws. Instrumentation of bridges with accelerometers and other sensors, however, can provide real-time data useful for monitoring the global structural conditions of the bridges due to ambient and forced excitations. Traditionally, videos are used for surveillance purposes and environmental monitoring of civil structures. In this paper the potential for the utilization of videos in an integrated structural health monitoring of highway bridges beyond the mentioned traditional applications are reported. Results obtained from the field tests, which were carried out on a short-span instrumented bridge, are presented. Videos of vehicles passing by, together with signals from laser beam sensors placed on the side of the bridge, were captured, and synchronized with data recordings from the accelerometers. For short-span highway bridges, vibration is predominantly due to traffic excitation. A stochastic model of traffic excitation on bridges is developed assuming that vehicles traversing a bridge (modeled as an elastic beam) form a sequence of Poisson process moving forces and that the contact force of a vehicle on the bridge deck can be converted to equivalent dynamic loads at the nodes of the beam elements. Basic information of vehicle types, arrival times and speeds are extracted from the video images to develop a physics-based simulation model of the traffic excitation. This modeling approach aims at circumventing a difficulty in the system identification of bridge structural parameters. Current practice of system identification of bridge parameters is often based on the measured response (or system output) only, and knowledge of the input (traffic excitation) is either unknown or assumed, making it difficult to obtain an accurate assessment of the state of the bridge structures. The effectiveness and viability of this video-assisted approach are demonstrated by the field results. Finally, a technique on how to integrate the weights of vehicles in the image processing algorithm is proposed.

Tan, Chin An; Beyene Ashebo, Demeke; Feng, Maria Q.; Fukuda, Yoshio

2007-05-01

435

An improved ZVZCS PWM FB DC\\/DC converter using the modified energy recovery snubber  

Microsoft Academic Search

The conventional high frequency phase-shifted full bridge DC\\/DC converter has a disadvantage 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 transformer and switching devices are increased. To alleviate that problem, the paper proposes a circulating current free type high frequency soft switching phase-shifted

Eun-Soo Kim; Kee-Yeon Joe; Soon-Gu Park; Yoon-Ho Kim

2000-01-01

436

High power factor control system in multilevel converters for AC heavy traction drives  

Microsoft Academic Search

A quasi-zero reactive power demand which is mandatory in single-phase AC (25 kV\\/50 Hz) traction systems is considered. Multilevel converter structures and high-performance control techniques have been developed to fulfil this goal in AC heavy traction drives. The tasks of the three level rectifier are described in detail. The current control logic is particularly suitable for applications to multilevel bridges.

T. Ghiara; M. Marchesoni; G. Sciutto

1990-01-01

437

Investigations on a unified controller for a practical hybrid multilevel power converter  

Microsoft Academic Search

This paper is devoted to the investigation of a practically feasible and commercially viable hybrid multilevel power converter topology typically suitable for active rectifier or static reactive power compensation applications at distribution voltage levels. This system comprises a three-phase neutral point clamped (NPC) main inverter supported by three auxiliary single-phase H-bridge inverters fed from independent DC links. The main and

Tilak Gopalarathnam; Madhav D. Manjrekar; Peter K. Steimer

2002-01-01

438

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

439

A Four-Level Converter with Optimized Switching Patterns for High-Speed Electric Drives  

Microsoft Academic Search

High-speed electrical machines at multi-MW power level are being designed to drive high-speed compressor trains in oil and gas industry applications and for directly driving generators with gas turbines for shipboard and mobile power generation applications. The paper describes a converter topology to address such high power high frequency drive requirements. The proposed topology uses a three-phase bridge with series-connected

Haiqing Weng; Kunlun Chen; Jianmei Zhang; Rajib Datta; Xianghui Huang; Luis J. Garces; Robert Wagoner; Allen M. Ritter; Paola Rotondo

2007-01-01

440

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

441

Unity Power Factor Control in Three-Phase AC\\/DC Boost Converter Using Sliding Modes  

Microsoft Academic Search

A problem of power factor correction for a class of three-phase boost ac\\/dc power converters is addressed in this paper. A full-bridge hardware topology is studied and used to address the basics of the efficient power conversion with high values of power factor. The sliding mode control drives the output voltage to the desired dc level in the presence of

Yuri Shtessel; Simon Baev; Haik Biglari

2008-01-01

442

A novel multilevel PWM control scheme of the AC\\/DC\\/AC converter for AC drives  

Microsoft Academic Search

An AC\\/DC\\/AC power converter with three-level pulse width modulation is proposed in this paper. A single-phase power factor correction circuit to improve the power quality in the rectifier and a three-level PWM inverter to reduce the harmonic contents of the inverter output voltages are presented. In the rectifier side, the hysteresis current control (HCC) technique for a bridge diode with

Bor-Ren Lin; Hsin-Hung Lu

1999-01-01

443

Component minimized AC\\/DC\\/AC converter with DC-link capacitors voltages balancing  

Microsoft Academic Search

This paper investigates component minimized topology of single-phase to three-phase AC\\/DC\\/AC pulse width modulated (PWM) converter. It consists of half-bridge rectifier and two-leg (B4) inverter and is designed for low-power induction machine (IM) drive application. Effect of voltage imbalance between split capacitor bank is discussed and improved control algorithm is proposed to minimize imbalance and compensate its impact on output

Krzysztof Rafal; Malgorzata Bobrowska; Jon A. Barrena; Marian P. Kazmierkowski

2009-01-01

444

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

Microsoft Academic Search

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

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

2011-01-01

445

Switched-capacitorized DC\\/DC converters  

Microsoft Academic Search

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

Fang Lin Luo

2009-01-01

446

Prediction of Impact Factor for Military Bridges.  

National Technical Information Service (NTIS)

A numerical study has been conducted on the dynamic response of nonuniform bridges subjected to the passage of heavy, multi-axle vehicles. For practical purposes, short span military bridges are made from lightweight components. As a consequence, the vehi...

V. J. Virchis

1979-01-01

447

Operación IceBridge: Explorando la Antártida  

NASA Video Gallery

Operación IceBridge es una misión aérea de la NASA dedicada a estudiar cambios en el hielo marino y terrestre en ambos polos del planeta. En octubre y noviembre de 2012, IceBridge completó su cuart...

448

Design and Construction of Modern Curved Bridges.  

National Technical Information Service (NTIS)

The overall objectives of this project were to investigate and synthesize state-of-the-art practice for the efficient design and construction of curved bridges, and to identify research needs regarding strength and stability of curved bridges. The project...

J. S. Davidson R. S. Abdalla M. Madhavan

2002-01-01

449

Underwater Inspection and Repair of Bridge Substructures.  

National Technical Information Service (NTIS)

This synthesis will be of special interest to bridge maintenance engineers and others concerned with the inspection and repair of bridge elements below the waterline. Problems with substructures are identified, and procedures, equipment, and techniques cu...

H. C. Lamberton A. J. Sainz R. A. Crawford W. B. Ogletree J. E. Gunn

1981-01-01

450

Stability of Curved Bridges During Construction.  

National Technical Information Service (NTIS)

Because of the increasing demand for curved bridges combined with challenges of design and construction, there is need to improve practices for the efficient design and construction of curved bridges. This report presents the results of two projects aimed...

J. S. Davidson R. S. Abdalla M. Madhavan

2004-01-01

451

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

452

Mechanics of Crack Bridging Under Dynamic Loads.  

National Technical Information Service (NTIS)

A bridging law for fiber reinforced composites under dynamic crack propagation conditions has been derived. Inertial effects in the mechanism of fiber pullout during dynamic propagation of a bridged crack are critically examined for the first time. By rep...

N. Sridhar B. N. Cox C. L. Dunn I. J. Beyerlein

2001-01-01

453

Practical Evaluations of a Novel Asymmetrical ZCS-PWM DC-DC Converter with High-Frequency Transformer-Link  

NASA Astrophysics Data System (ADS)

This paper presents a novel Zero Current Switching (ZCS)-PWM controlled half-bridge DC-DC converter with High-Frequency (HF)-link. The newly-proposed soft switching DC-DC converter consists of a multi-resonant half-bridge HF-isolated inverter controlled by an asymmetrical PWM scheme and a center-tapped diode rectifier with a choke input filter. In order to attain the wide range of soft-commutation under the condition of constant switching frequency, the single Active Edge-Resonant Cell (AERC) that is composed of a lossless inductor and a switched resonant capacitor is originally employed for the half-bridge inverter arm, providing and assisting ZCS operations in the switching power devices. The ZCS-PWMDC-DC converter treated here is evaluated in experiments using the 800 W-55 kHz prototype. The practical effectiveness of the proposed soft switching DC-DC converter is actually demonstrated and discussed with the experimental results under open loop and closed loop configurations. Finally, the feasibility of the DC-DC converter topology is discussed from the view points of the high efficiency and high power density.

Mishima, Tomokazu; Hiraki, Eiji; Nakaoka, Mutsuo

454

"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

455

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

456

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

457

EOS NPOESS the Bridge Mission  

NSDL National Science Digital Library

A Dynamic proposal between the National Aeronautics and Space Administration and the National Polar Orbiting Environmental Satellite System Integrated Program Office. A project to bridge or link between the operations of the Earth Observing System AM-1 and the PM-1 Spacecraft and the National Polar Orbiting Environmental Satellite System Spacecraft (NPOESS)

Carnahan, Tim; Snodgrass, Stuart; Murphy, Robert

1999-02-02

458

Bridge Standards-Local Governments.  

National Technical Information Service (NTIS)

In the study a survey was conducted to ascertain the needs of employees of local governmental agencies with regard to the conduct of the design of bridges. Recommendations, relative to the development of standard plans which can be used by county engineer...

H. C. Sorensen

1988-01-01

459

Adhesive Development for Military Bridging.  

National Technical Information Service (NTIS)

The objective of this effort was to develop a family of adhesives suited to structural bonding of U.S. Army bridge members. To be joined were: aluminum to aluminum, aluminum to composite, and composite to composite materials. The adhesives should be non-b...

D. I. Basiulis E. Catsiff R. D. Hermansen S. E. Lau W. E. Elias

1988-01-01

460

Evaluation of Summer Bridge Programs  

ERIC Educational Resources Information Center

Many colleges and universities in the United States offer summer programs for their incoming students. While programs are structured and administered in a variety of ways and target various student populations, the most common type of summer bridge program aims to serve historically underrepresented students and students of low socioeconomic…

Garcia, Lisa D.; Paz, Chiara C.

2009-01-01

461

AGU receives Crystal Bridge Award  

Microsoft Academic Search

On 23 June the San Francisco Travel Association presented AGU with its Crystal Bridge Award, given to honor major convention customers who bring outstanding events with significant impact to San Francisco, Calif. For the past 43 years, AGU has held its Fall Meeting in San Francisco; for the past 17 years the meeting has been at San Francisco's Moscone Center.

Brenda Weaver

2011-01-01

462

Evaluating Concrete Bridge Deck Performance.  

National Technical Information Service (NTIS)

Since the service life of concrete bridge decks designed by traditional procedures is often shorter than desired, their ability to withstand constant and heavy use in a variety of operating environments is of major concern. In this project, the relative p...

E. Cuelho J. Johnson J. Stephens P. Smolenski

2006-01-01

463

Parametric studies on cable-stayed bridges  

Microsoft Academic Search

Parametric studies on cable-stayed bridges are performed in the paper for investigating the individual influence of different sources of nonlinearity in such bridges. The sources of nonlinearity in the cable-stayed bridge mainly include the large deflection, beam-column and cable sag effects. The influence of such kind of effects on the analysis and the structural behavior of cable-stayed bridges has been

Pao-Hsii Wang; Chiung-Guei Yang

1996-01-01

464

Suicide from the Golden Gate Bridge.  

PubMed

The Golden Gate Bridge is the number one suicide site in the world. In this clinical case conference, the authors begin by presenting vignettes to capture the diversity of bridge suicide. They then examine the demographic characteristics of those who commit suicide from the bridge as well as the fatal attraction of the Golden Gate Bridge. Interviews with jump survivors and potential jumpers are presented, and the authors examine the evidence for the efficacy of suicide barriers. PMID:19797444

Blaustein, Mel; Fleming, Anne

2009-10-01

465

49 CFR 237.71 - Determination of bridge load capacities.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Determination of bridge load capacities. 237.71 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Capacity of Bridges § 237.71 Determination of bridge load...

2010-10-01

466

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

467

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

468

49 CFR 237.109 - Bridge inspection records.  

Code of Federal Regulations, 2010 CFR

... 4 2010-10-01 2010-10-01 false Bridge inspection records. 237.109 Section 237...RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection § 237.109 Bridge inspection...

2010-10-01

469

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

470

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

471

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

472

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

473

49 CFR 237.71 - Determination of bridge load capacities.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Determination of bridge load capacities. 237.71 Section 237...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Capacity of Bridges § 237.71 Determination of bridge load...

2013-10-01

474

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

475

Time Domain Buffeting Analysis of Suspension Bridges Subjected to Turbulent Wind with Effective Attack Angle  

NASA Astrophysics Data System (ADS)

Suspension bridges are long-span flexible structures susceptible to various types of wind-induced vibrations such as buffeting actions. In this paper, a three-dimensional finite element model formulated to deal with suspension bridges under turbulent wind with effective attack angle is presented. In this model, all sources of geometric non-linearity such as cable sag, force-bending moment interaction in the bridge deck and towers as well as changes in bridge geometry due to large displacements are fully considered. The wind loads which include buffeting loads and self-excited loads are converted into the time domain by using a computer simulation technique to form aerodynamic damping and stiffness matrices as well as element loading vectors. Furthermore, a more refined model of wind loads is constructed in order to investigate the effect of an instantaneous change in effective attack angle of turbulent wind on bridge buffeting response. By comparing the results with those obtained by classic buffeting theory through an example bridge, the validity of the presented method is verified.

DING, Q.; LEE, P. K. K.; LO, S. H.

2000-06-01

476

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

477

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

478

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

479

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

480

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

481

Rehabilitation of Precast Deck Panel Bridges  

Microsoft Academic Search

USF completed a research study in 2005, which prioritized the replacement of 85 deteriorating composite precast deck panel bridges. This thesis re-evaluates the original recommendations in the wake of failures of two of these bridges in 2007. Since funding will not allow all identified bridges to be replaced, it was necessary to determine the most effective repair methods. To assess

Atiq H. Alvi

2010-01-01

482

Shake Table Testing of Lightweight Concrete Bridges.  

National Technical Information Service (NTIS)

This report is the third in a series on the seismic behavior of lightweight concrete bridges. Presented are the results of a series of shake table tests on lightweight concrete bridges. A pair of two column bridge bents were designed and tested on the UCS...

F. Seible M. Kowalsky N. Priestley

1997-01-01

483

Probalistic analysis of highway bridge traffic loading  

Microsoft Academic Search

Many bridges of the world’s highway networks have been in service for decades and are subject to escalating volumes of traffic. Consequently, there is a growing need for the rehabilitation or replacement of bridges due to deterioration and increased loading. The assessment of the strength of the existing bridge is relatively well understood, whereas the traffic loading it is subject

Colin C. Caprani

2005-01-01

484

Structural behaviour of aluminium bridge deck panels  

Microsoft Academic Search

The use of lightweight bridge decks made of FRP composites or aluminium alloys is particularly effective for replacing deteriorated bridge decks. Therefore a research program has been undertaken to develop and implement an innovative aluminium bridge deck system, which would be applicable and realizable in domestic conditions. Several service load and ultimate load tests have been carried out on the

Tomasz W. Siwowski

2009-01-01

485

The breaking of axisymmetric slender liquid bridges  

Microsoft Academic Search

Liquids held by surface tension forces can bridge the gap between two solid bodies placed not too far apart from each other. The equilibrium conditions and stability criteria for static, cylindrical liquid bridges are well known. However, the behaviour of an unstable liquid bridge, regarding both its transition toward breaking and the resulting configuration, is a matter for discussion. The

J. Meseguer

1983-01-01

486

?-Bridged BODIPY oligomers with switchable near-IR photoproperties by external-stimuli-induced foldamer formation and disruption.  

PubMed

We designed and synthesized a series of new ?-bridged linear BODIPY oligomers, which exhibited strong absorption and high fluorescence efficiency in the near infrared region. The oligomers can be reversibly converted to the first NIR emissive BODIPY foldamers upon selective complexation with Cs(+). PMID:22302032

Sakamoto, Naoya; Ikeda, Chusaku; Yamamura, Masaki; Nabeshima, Tatsuya

2012-05-18

487

Portable convertible blast effects shield  

DOEpatents

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

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

2010-10-26

488

Portable convertible blast effects shield  

DOEpatents

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

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

2007-05-22

489

Portable convertible blast effects shield  

DOEpatents

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

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

2011-03-15

490

An improved interleaved forward converter  

Microsoft Academic Search

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

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

2006-01-01

491

Resonant converter power line conditioner  

Microsoft Academic Search

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

S. Deb; R. G. Hoft

1988-01-01

492

High efficiency thermionic converter studies  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

493

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

494

Theory of water and charged liquid bridges  

NASA Astrophysics Data System (ADS)

The phenomenon of liquid bridge formation due to an applied electric field is investigated. A solution of a charged catenary is presented, which allows one 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 are 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.

Morawetz, K.

2012-08-01

495

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

Microsoft Academic Search

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

Tasi-Fu Wu; Yu-Kai Chen

1998-01-01

496

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.

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

2012-01-01

497

Characteristics of an Equidistant Firing System in 12-Pulse Converter Bridges for HVDC.  

National Technical Information Service (NTIS)

This research paper deals with the construction of a simulation model for a twelve pulse HVDC transmission line. The realized equidistant pulse phase control system is suitable for the operation in weak or strongly unbalanced ac systems from the viewpoint...

K. Juslin Y. Laiho V. Vauhkonen

1981-01-01

498

Diode-quad bridge circuit means  

NASA Technical Reports Server (NTRS)

Diode-quad bridge circuit means is described for use as a transducer circuit or as a discriminator circuit. It includes: (1) a diode bridge having first, second, third, and fourth bridge terminals consecutively coupled together by four diodes polarized in circulating relationship; (2) a first impedance connected between the second bridge terminal and a circuit ground; (3) a second impedance connected between the fourth bridge terminal and the circuit ground; (4) a signal source having a first source terminal capacitively coupled to the first and third bridge terminals, and a second source terminal connected to the circuit ground; and (5) an output terminal coupled to the first bridge terminal and at which an output signal may be taken.

Harrison, D. R.; Dimeff, J. (inventors)

1975-01-01

499

Experimental Study on Alkali Metal Thermoelectric Converter.  

National Technical Information Service (NTIS)

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

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

1989-01-01

500

Large wind energy converter: Growian 3 MW  

NASA Technical Reports Server (NTRS)

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

Koerber, F.; Thiele, H. A.

1979-01-01