Sample records for bridge flyback converter

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

    SciTech Connect

    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

    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)

  2. Coupled Dual Interleaved Flyback Converter for High Input Voltage Application

    E-print Network

    Lehman, Brad

    -Bridge [5,6], and buck-boost mode topologies, such as dual Flyback [9,10]. More recently, there are newly for buck mode topologies. Historically, magnetic integration is utilized for Forward converters [1Coupled Dual Interleaved Flyback Converter for High Input Voltage Application Ting Qian, Brad

  3. Quasiresonant flyback converter for transdermal drug delivery applications

    Microsoft Academic Search

    S.-Y. Tseng; Y.-M. Chen; Y.-K. Huang; H.-T. Hsieh; T.-F. Wu

    2004-01-01

    This paper explores a new application field of power electronics. A soft-switching quasiresonant flyback converter is designed for transdermal drug delivery (TDD) applications with the processes of electroporation and phonophoresis. The converter can generate a constant DC voltage output for a pulsed generator in electroporation processing and can generate a variable DC voltage to drive a radial type of piezoelectric

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

    SciTech Connect

    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

    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.

  5. Performance comparison of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) flyback converters

    Microsoft Academic Search

    S. Howimanporn; C. Bunlaksananusorn

    2003-01-01

    This paper presents performance comparison of continuous conduction mode (CCM) and discontinuous conduction mode (DCM) flyback converters. The comparison is conducted through experiment on the 5 V\\/25 W, 50 kHz prototype CCM and DCM flyback converters, which have been designed and built with similar circuit layouts, components, and power ratings. Aspects to be compared are component stress, output voltage regulation

  6. Interleaved boost-flyback converter with boundary conduction mode for power factor correction

    Microsoft Academic Search

    Bor-Ren Lin; Chia-Hung Chao; Chih-Cheng Chien

    2011-01-01

    This paper presents a new interleaved pulse-width modulation (PWM) boost-flyback converter to achieve power factor correction (PFC) and regulate DC bus voltage. The adopted boost-flyback converter has a high voltage conversion ratio to overcome the limit of conventional boost or buck-boost converter with narrow turn-off period. The proposed converter has wide turn-off period compared with a conventional boost converter. Thus

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

    E-print Network

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

    2004-01-01

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

  8. Microbial fuel cell energy harvesting using synchronous flyback converter

    NASA Astrophysics Data System (ADS)

    Alaraj, Muhannad; Ren, Zhiyong Jason; Park, Jae-Do

    2014-02-01

    Microbial Fuel Cells (MFCs) use biodegradable substrates, such as wastewater and marine sediments to generate electrical energy. To harvest more energy from an MFC, power electronic converters have recently been used to replace resistors or charge pumps, because they have superior controllability on MFC's operating point and higher efficiency in energy storage for different applications. Conventional diode-based energy harvesters suffer from low efficiency because of the energy losses through the diode. Replacing the diode with a MOSFET can reduce the conduction loss, but it requires an isolated gate signal to control the floating secondary MOSFET, which makes the control circuitry complex. This study presents a new MFC energy harvesting regime using a synchronous flyback converter, which implements a transformer-based harvester with much simpler configuration and improves harvesting efficiency by 37.6% compared to a diode based boost converter, from 33.5% to 46.1%. The proposed harvester was able to store 2.27 J in the output capacitor out of 4.91 J generated energy from the MFC, while the boost converter can capture 1.67 J from 4.95 J.

  9. Soft-Switching Zeta–Flyback Converter With a Buck–Boost Type of Active Clamp

    Microsoft Academic Search

    Bor-Ren Lin; Fang-Yu Hsieh

    2007-01-01

    This paper presents the system analysis, design consideration, and implementation of a soft-switching zeta-flyback converter to achieve zero-voltage switching (ZVS). In the proposed converter, the zeta and flyback topologies are adopted in the output side to achieve the following features: to share the power components in the transformer primary side, to achieve the partial magnetizing flux reset, and to share

  10. Design of a simple high-power-factor rectifier based on the flyback converter

    Microsoft Academic Search

    Robert Erickson; Michael Madigan; Sigmund Singer

    1990-01-01

    An equivalent circuit model for the discontinuous conduction mode flyback converter based on the loss-free resistor concept is presented. This simple model correctly describes the basic power processing properties of the converter, including input port resistor emulation, output port power source characteristics, and control characteristics. Based on this model, steady-state design equations are described and are used in a design

  11. Planar LTCC transformers for high voltage flyback converters.

    SciTech Connect

    Schofield, Daryl (NASCENT Technology Inc. , Watertown, SD); Schare, Joshua M.; Glass, Sarah Jill; Roesler, Alexander William; Ewsuk, Kevin Gregory; Slama, George (NASCENT Technology Inc. , Watertown, SD); Abel, Dave (NASCENT Technology Inc. , Watertown, SD)

    2007-06-01

    This paper discusses the design and use of low-temperature (850 C to 950 C) co-fired ceramic (LTCC) planar magnetic flyback transformers for applications that require conversion of a low voltage to high voltage (> 100V) with significant volumetric constraints. Measured performance and modeling results for multiple designs showed that the LTCC flyback transformer design and construction imposes serious limitations on the achievable coupling and significantly impacts the transformer performance and output voltage. This paper discusses the impact of various design factors that can provide improved performance by increasing transformer coupling and output voltage. The experiments performed on prototype units demonstrated LTCC transformer designs capable of greater than 2 kV output. Finally, the work investigated the effect of the LTCC microstructure on transformer insulation. Although this paper focuses on generating voltages in the kV range, the experimental characterization and discussion presented in this work applies to designs requiring lower voltage.

  12. A Digitally Controlled DCM Flyback Converter With a Low-Volume Dual-Mode Soft Switching

    E-print Network

    Prodiæ, Aleksandar

    A Digitally Controlled DCM Flyback Converter With a Low-Volume Dual-Mode Soft Switching Circuit conduction mode (DCM). The new ZVS/ZCS solution provides soft switching feature and high efficiency operating in discontinuous conduction mode (DCM) is widely used in power factor correction rectifiers

  13. Synthetic design of the transformer in flyback switching AC-DC converters

    Microsoft Academic Search

    Ge Chen; Jiaxin Chen; Youguang Guo; Jianguo Zhu

    2008-01-01

    This paper presents the synthetic design of the transformer in flyback switching AC-DC converters. Firstly, the maximal power transferred by a standard size magnetic core such as EE-20 or EE-25 is theoretically determined. To obtain accurate analysis, a method based on the nonlinear finite element analysis (FEA) of electromagnetic field is employed. Secondly, from the view of reducing the maximal

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

    Microsoft Academic Search

    Dong Wang; Xiangning He; Jianjiang Shi

    2010-01-01

    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.

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

    Microsoft Academic Search

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

    2010-01-01

    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

  16. Performance analysis and circuit design of an interleaved active clamp zero voltage switching Flyback-Forward boost converter

    Microsoft Academic Search

    Fengwen Cao; Yiwang Wang; Ji Suo; Chunqing Qi; Qingrui Tu

    2010-01-01

    An isolated interleaved zero voltage switching (ZVS) Flyback-Forward boost type converter with active clamp scheme is designed in this paper. Both the main and the clamp switches canswitching losses operate with ZVS soft switching performance to reduce the switching losses. Furthermore, the leakage energy is recycled and the turn-off voltage spikes on the main switches are absorbed by the active

  17. Full bridge converter Transformers and isolated converters

    E-print Network

    Knobloch,Jürgen

    control. 2. High power factor PFC - discussed previously. 3. Isolation 4. Multiple outputs IsolatedFull bridge converter Transformers and isolated converters Most DC power supplies have the following requirements: 1. Regulated output voltage Solved by a large capacitor at the output, and feedback

  18. Estudio Comparativo entre los Convertidores Flyback y Flyback Multifase para Corrección Activa del Factor de Potencia

    Microsoft Academic Search

    Luis Alejandro Flores Oropeza; Eleazar Padilla Guardado; Alejandro Román Loer; Luis Enrique; Arámbula Miranda

    2008-01-01

    This paper proposes a multiphase flyback converter for the correction active of power factor as a viable alternative to a single conventional flyback converter. Similarly, there are advantages to be gained by using a multiphase converter front of a single converter for the correction of active power factor. This paper, presents the results in simulation as well as the advantages

  19. High Efficiency Single Output ZVS-ZCS Voltage Doubled Flyback Converter

    NASA Astrophysics Data System (ADS)

    Kaliyaperumal, Deepa; Saju, Hridya Merin; Kumar, M. Vijaya

    2014-12-01

    A switch operating at high switching frequency increases the switching losses of the converter resulting in lesser efficiency. Hence this paper proposes a new topology which has resonant switches [zero voltage switching (ZVS)] in the primary circuit to eliminate the above said disadvantages, and voltage doubler zero current switching (ZCS) circuit in the secondary to double the output voltage, and hence the output power, power density and efficiency. The design aspects of the proposed topology for a single output of 5 V at 50 kHz, its simulation and hardware results are discussed in detail. The analysis of the results obtained from a 2.5 W converter reveals the superiority of the proposed converter.

  20. Thermographic Analysis of a Bridge Power Converter

    NASA Astrophysics Data System (ADS)

    Anna, V. Andonova; Nikolay, L. Hinov

    2015-01-01

    Any loss of power in converters is dissipated as heat in the components of the circuit. The article presents a new approach to measuring heat dissipation in a bridge power converter with hard switches using infrared thermography. Parallel measurements by thermocouples have been carried out. The experimental results are compared and used from the both cases. The proposed approach can be used for various circuit implementations of the converters in a similar manner.

  1. Present States and Development of the Single-stage Uninterruptible AC-DC Converters

    Microsoft Academic Search

    Daolian Chen

    2009-01-01

    Circuit topologies of single-stage, single-stage combined, single-stage paralled uninterruptible AC-DC converters with high power factor are proposed based on presenting research present states of the single-stage uninterruptible AC-DC converters. This kind of AC-DC converters, which is constituted of full-bridge rectifier and multifunctional integrated flyback converter, can realize uninterruptible power supply, power factor correction, and dc output voltage's regulation. Three operating

  2. Cycling firing method for bypass operation of bridge converters

    DOEpatents

    Zabar, Zivan (99-72 66th Rd., Apt. 9N, Forest Hills, NY 11375)

    1982-01-01

    The bridge converter comprises a number of switching elements and an electronic logic system which regulated the electric power levels by controlling the firing, i.e., the initiation of the conduction period of the switching elements. Cyclic firing of said elements allows the direct current to bypass the alternating current system with high power factor and negligible losses.

  3. A dual bridge high current DC-to-DC converter with soft switching capability

    Microsoft Academic Search

    Nasser H. Kutkut; Glen Luckjiff; Deepak M. Divan

    1997-01-01

    This paper presents a dual bridge high current DC-to-DC converter with soft switching capability. The proposed dual bridge power supply is based on the two switch isolated forward converter. Unlike conventional dual bridge forward converters, phase shift control is employed to regulate the output voltage and achieve soft switching. In addition, a single high frequency power transformer is proposed to

  4. Low Cost Embedded Controlled Full Bridge LC Parallel Resonant Converter

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, P.; Reddy, S.

    2009-01-01

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

  5. Active-clamp snubbers for isolated half-bridge DC-DC converters

    Microsoft Academic Search

    Hong Mao; Songquan Deng; Jaber Abu-Qahouq; Issa Batarseh

    2005-01-01

    In conventional isolated half-bridge dc-dc converters, the leakage-inductance-related losses degrade converter efficiency and limit the ability to increase the converters' switching frequencies. In this paper, a novel active-clamp snubber circuit for half-bridge dc-dc converters is proposed to recycle the energy stored in the leakage inductance by transferring this energy to a capacitor with zero-voltage zero-current-switching switched auxiliary switches, such that

  6. A Novel ZVZCS Full-Bridge DC\\/DC Converter Used for Electric Vehicles

    Microsoft Academic Search

    Majid Pahlevaninezhad; Pritam Das; Josef Drobnik; Praveen K. Jain; Alireza Bakhshai

    2012-01-01

    This paper presents a novel ZVZCS full-bridge DC\\/DC converter, which is able to process and deliver power efficiently over very wide load variations. The proposed DC\\/DC converter is part of a plug-in AC\\/DC converter used to charge the traction battery (high voltage battery) in an electric vehicle. The key challenge in this application is operation of the full-bridge converter from

  7. Key Issues of Clamping Diodes in DCM Phase-Shift Full-Bridge Converter

    Microsoft Academic Search

    Lanlan Yin; Qianhong Chen; Bo Peng; Jian Wang; Xinbo Ruan

    2007-01-01

    When the phase-shifted full-bridge converter (PSFB converter) with clamping diodes (CD) operating in discontinuous current mode (DCM), clamping diodes are apt to be damaged, especially in high input voltage applications, which deteriorates the reliability of the converter dramatically. The operation principle of the DCM PSFB converter with CD is analyzed in detail. Analysis shows that the clamping diode has different

  8. Zero voltage soft-commutation PWM DC-DC converter with saturable reactor switch-cascaded diode rectifier

    Microsoft Academic Search

    Junming Sun; Satoshi Hamada; Junji Yoshitsugu; Bin Guo; Mutsuo Nakaoka

    1998-01-01

    An improved single-ended push-pull (SEPP) half-bridge type zero-voltage soft-switching pulse width modulation (ZVS-PWM) DC-DC power converter is presented in this paper, which makes use of a saturable reactor-assisted lossless capacitor type zero voltage soft-switching method. The SEPP power converter with a high-frequency forward and flyback hybrid transformer link has some advantages such as lowered switching and conduction losses, soft-switching transition

  9. A fully soft-switched ZVZCS Full-Bridge PWM converter

    Microsoft Academic Search

    Mohsen Packnezhad; Hosein Farzanehfard

    2009-01-01

    A zero-voltage and zero-current switching full-bridge pulse width modulation (ZVZCS-FB-PWM) converter is proposed to improve the performance of existing converter with active clamp. The proposed converter can eliminate the switching loss of the active clamp switch. Efficiency is improved since the clamp switch operates at twice the converter switching frequency. The topology including the clamp circuit is very simple with

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

    SciTech Connect

    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

    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.

  11. A Pulse-Frequency-Modulated Full-Bridge DC\\/DC Converter With Series Boost Capacitor

    Microsoft Academic Search

    Yong-Saeng Shin; Chang-Seop Kim; Sang-Kyoo Han

    2011-01-01

    The conventional zero-voltage switching phase-shift full-bridge (ZVS PSFB) converter has a large circulating energy during the freewheeling interval caused by the small duty cycle, which could increase the primary-side conduction losses, the turn-off switching losses of lagging-leg switches, and the current ripple through the output inductor. To overcome these problems, this paper proposes a new pulse-frequency-modulated full-bridge direct-current (dc)\\/dc converter

  12. Zero voltage and zero current switching full bridge PWM converter using secondary active clamp

    Microsoft Academic Search

    Jung G. Cho; Geun H. Rim; Fred C. Lee

    1996-01-01

    A new zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to improve the performance of the previously presented ZVZCS-FB-PWM converters. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS (for leading leg switches) and ZCS (for lagging leg switches) are achieved without any lossy components, the reverse avalanche break down

  13. A Universal Functional Electrical Stimulator Based on Merged Flyback-SC Circuit

    E-print Network

    Prodiæ, Aleksandar

    A Universal Functional Electrical Stimulator Based on Merged Flyback-SC Circuit Santa C. Huerta1 novel functional electrical stimulation (FES) system architecture. Compared to the existing state -- FES, DC-DC converters, digital control. I. INTRODUCTION Functional electrical stimulation (FES) [1

  14. Radiation Effects on DC-DC Converters

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  15. Hybrid Full-Bridge Three-Level LLC Resonant Converter—A Novel DC–DC Converter Suitable for Fuel-Cell Power System

    Microsoft Academic Search

    Ke Jin; Xinbo Ruan

    2006-01-01

    This paper proposes a novel hybrid full-bridge (H-FB) three-level (TL) LLC resonant converter. It integrates the advantages of the H-FB TL converter and the LLC resonant converter. It can operate under both three-level mode and two-level mode, so it is very suitable for wide-input-voltage-range applications, such as fuel-cell power systems. Compared with the traditional full-bridge converter, the input current ripple

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

    Microsoft Academic Search

    Jung G. Cho; Juan A. Sabate; Guichao Hua; Fred C. Lee

    1994-01-01

    A novel zero-voltage and zero-current-switching (ZVZCS) full bridge (FB) PWM converter is proposed. The new converter overcomes the limitations of the ZVS-FB-PWM converter such as high circulating energy, severe parasitic ringing on the rectifier diodes, and limited ZVS load range for lagging leg switches. By utilizing the DC blocking capacitor and adding a saturable inductor, the primary current during the

  17. Analysis and design considerations of zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converters

    Microsoft Academic Search

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

    2002-01-01

    In this paper, a detailed analysis of the zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converters is performed. The differences of the zero-voltage-switching (ZVS) operation between the conventional ZVS full-bridge PWM converters and the ZVZCS full-bridge PWM converters are analyzed in depth. Circuit parameters that affect the soft-switching conditions are examined and the critical parameters are identified. Based on the analysis,

  18. Research and improvement of a zero-voltage zero-current switching full-bridge converter

    Microsoft Academic Search

    Yan Bao; Sheng Li; Jiuchun Jiang; Weige Zhang

    2008-01-01

    As is known to all, full-bridge topology is one of the most common circuits in the field of power technology. In pursuit of the efficient and diminutive power equipment all the while, soft-switching technology has been widely applied as an important instrument at present. In this paper, a novel zero-voltage zero-current switching (ZVZCS) full-bridge DC\\/DC converter is presented to improve

  19. Hybrid half- and full-bridge converter with high efficiency and full soft-switching range

    Microsoft Academic Search

    Wensong Yu; Jih-Sheng Lai; Wei-Han Lai; Hongmei Wan

    2011-01-01

    A novel soft-switching converter combining resonant half-bridge and phase shifted full-bridge configuration is proposed to ensure the switches in the leading-leg operating at zero-voltage switching from true zero to full load, and the switches in the lagging-leg at zero-current switching with minimum duty cycle loss and circulating conduction loss by significantly reducing leakage or series inductance. A 3.4 kW hardware

  20. Static and dynamic analysis of zero-voltage-switched half-bridge converter with PWM control

    Microsoft Academic Search

    T. Ninomiya; N. Matsumoto; M. Nakahara; K. Harada

    1991-01-01

    The static and dynamic characteristics of a zero-voltage-switched half-bridge converter are analyzed quantitatively. This converter is controlled by pulse width modulation (PWM) with the asymmetrical drive of a pair of semiconductor switches and the zero-voltage switching is maintained by the partial resonance during the off interval of both switches. The effects of circuit parameters, such as the input capacitance, and

  1. Zero-Voltage- and Zero-Current-Switching Full-Bridge Converter With Secondary Resonance

    Microsoft Academic Search

    Eung-Ho Kim; Bong-Hwan Kwon

    2010-01-01

    A zero-voltage- and zero-current-switching full-bridge (FB) converter with secondary resonance is presented and analyzed. The primary side of the converter is composed of FB insulated-gate bipolar transistors, which are driven by phase-shift control. The secondary side is composed of a resonant tank and a half-wave rectifier. Without an auxiliary circuit, zero-voltage switching (for leading-leg switches) and zero-current switching (for lagging-leg

  2. An improved zero voltage and zero current switching full bridge PWM converter with secondary active clamp

    Microsoft Academic Search

    J. W. Baek; J. G. Cho; D. W. Yoo; G. H. Rim; H. G. Kim

    1998-01-01

    An improved zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to solve the problems of the previously presented ZVZCS-FB-PWM converter with secondary active clamp such as narrow ZVS range of leading-leg switches. By adding an auxiliary inductor in between the leading-leg and separated input source voltages, the ZVS of leading leg switches can be

  3. Full bridge DC-DC converter with zero voltage resonant transition switching and immersion cooling

    Microsoft Academic Search

    C. P. Henze

    1992-01-01

    A full-bridge topology was used to implement a family of DC-DC power converters which operate with zero voltage resonant transition (ZVRT) switching and a modified pulse width modulation technique at nominal output voltages ranging from 2.0 to 6.0 V DC at full load currents ranging from 1400 to 1000 A DC. Liquid-immersion cooling was used. The converter was packaged in

  4. A simple three-phase single-stage ac-dc ZVZCS full bridge converter

    Microsoft Academic Search

    Dunisha Wijeratne; Gerry Moschopoulos

    2009-01-01

    A new three-phase AC-DC single-stage PWM full-bridge converter is proposed in the paper. The outstanding features of the converter are that it can simultaneously perform input power factor correction (PFC) and isolated dc-dc conversion, it can operate using standard phase-shift PWM control, it is simple and low cost, and it has a dc bus capacitor that allows it operate with

  5. A novel zero-current-transition full bridge DC\\/DC converter

    Microsoft Academic Search

    Junming Zhang; Xiaogao Xie; Xinke Wu; Guoliang Wu; Zhaoming Qian

    2006-01-01

    This paper proposes a novel zero-current-transition pulse-width modulation full-bridge dc\\/dc converter. The proposed converter not only achieves zero current switching for the main switches and auxiliary switch in the entire load ranges, but it also realizes soft commutation for the output rectifier diodes. Furthermore, the auxiliary circuit also helps to turn on the main switches softly. Simulation results and experimental

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

    Microsoft Academic Search

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

    2001-01-01

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

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

    Microsoft Academic Search

    Mangesh Borage; Sunil Tiwari; S. Kotaiah

    2003-01-01

    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

  8. A new mode changeable full bridge dc\\/dc converter for wide input voltage range

    Microsoft Academic Search

    Yong-Saeng Shin; Sung-Soo Hong; Dong-Joong Kim; Dong-Sung Oh; Sang-Kyoo Han

    2011-01-01

    Generally, a zero voltage switching (ZVS) phase shift full bridge (PSFB) converter is suitable for high power density\\/high efficiency application and its efficiency is maximized at 50% duty cycle. However, the steady state duty cycle is as small as approximately 30% at full load and nominal input voltage conditions which is because the PSFB must be designed to be ensure

  9. Soft Switched Full Bridge DC–DC Converter With Reduced Circulating Loss and Filter Requirement

    Microsoft Academic Search

    Xinke Wu; Xiaogao Xie; Junming Zhang; Rongxiang Zhao; Zhaoming Qian

    2007-01-01

    A new soft switched full bridge converter with phase-shift control is proposed to reduce the circulating loss in primary and the voltage stress in secondary side. Using a coupled winding of the filter inductor, two auxiliary voltage sources are generated to reset the primary current at circulating interval. An auxiliary clamp diode is used to clamp the voltage spike across

  10. A pulse frequency modulated full bridge DC\\/DC converter with series boost capacitor

    Microsoft Academic Search

    Yong-Saeng Shin; Chung-Wook Roh; Sung-Soo Hong; Sang-Kyoo Han

    2010-01-01

    The conventional Zero Voltage Switching (ZVS) Phase Shift Full Bridge converter(PSFB) has large circulating energy during freewheeling interval caused by the small duty cycle, which could increase the primary side conduction losses, turn off switching losses of lagging leg switches and current ripple through the output inductor. To overcome these problems, this paper proposes a new pulse frequency modulated full

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

    Microsoft Academic Search

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

    2002-01-01

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

  12. A novel ZVZCS full-bridge PWM DC-DC converter with active voltage clamp and energy recovery circuit

    Microsoft Academic Search

    Tiecheng Sun; Xueguang Zhang; Pinghua Tang; Lin Mei

    2005-01-01

    An improved zero voltage and zero current switching (ZVZCS) full-bridge (FB) PWM DC-DC converter is proposed. The new converter overcomes drawbacks such as voltage ringing and voltage overshoot in conventional ZVZCS converter. An auxiliary circuit consists of auxiliary switcher, clamping capacitor, diode rectifier and energy recovery transformer. The auxiliary circuit alleviates the voltage ringing and voltage overshoot in secondary side

  13. Analysis of an improved zero-voltage and zero-current switching (ZVZCS) full bridge DC-DC PWM converter

    Microsoft Academic Search

    Yang Xiaobo; Zhou Huisheng; Shen Hong; Zheng Yingnan

    2004-01-01

    By the analysis of the ZVZCS phase shifted full bridge PWM DC-DC converter with secondary auxiliary circuit, the parameters of the circuit are optimized to improve the performance of the converter. The conditions to achieve ZVS (leading-leg) and ZCS (lagging leg) are discussed. The loss of the ZVZCS. converter is decreased under the novel working mode. The principle of operation

  14. Comparison of zero-voltage-switching current-fed full-bridge and half-bridge isolated Dc\\/Dc converters with active-clamp

    Microsoft Academic Search

    Akshay K Rathore; Xiaodong Li

    2011-01-01

    This short paper presents a comparison between high-frequency current-fed full-bridge and half-bridge isolated dc\\/dc converters with active-clamp snubber. Active-clamp snubber, in addition to absorbing the turn-off voltage spike across the switch, acts as a zero-voltage transition auxiliary circuit resulting in zero-voltage switching (ZVS) of the semiconductor devices of converters. ZVS range depends upon the design, in particular, ratio of leakage

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

    Microsoft Academic Search

    Georgios S. Konstantinou; Vassilios G. Agelidis

    2009-01-01

    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

  16. Zero-voltage and zero-current-switching half bridge DC\\/DC converter

    Microsoft Academic Search

    Vencislav Valchev; Dimitre Yudov; J. Batchvarov; A. Van den Bossche; J. Melkebeek

    2002-01-01

    This paper introduces an improved zero-voltage and zero-current-switching half bridge (ZV-ZCS HB) DC\\/DC converter for medium and high-power applications. The soft switching is obtained by adding only small capacitors. The operation principle and design procedure are presented together with an analysis of the total losses in the switch. By using the proposed operation principle and design procedure zero-voltage-zero-current switching and

  17. A novel full-bridge ZVZCS PWM DC\\/DC converter with a secondary clamping circuit

    Microsoft Academic Search

    Byeong-Hoo Choo; Dong-Yun Lee; Sang-Bong Yoo; Dong-Seok Hyun

    1998-01-01

    This paper proposes a novel secondary clamping circuit for soft switching FB (full-bridge) PWM DC\\/DC converter. The proposed circuit eliminates the reflected output current which is reflected from the secondary side to the primary side so that it reduces the needless conduction losses of the primary side during the current circulating mode. Also, it ensures the zero-voltage\\/zero-current switching of the

  18. Zero-voltage-switching PWM hybrid full-bridge three-level converter

    Microsoft Academic Search

    Xinbo Ruan; Zhiying Chen; Wu Chen

    2005-01-01

    This paper proposes a zero-voltage-switching (ZVS) pulse-width modulation (PWM) hybrid full-bridge three-level converter, which has a three-level leg and a two-level leg. The switches of the three-level leg sustain only the half of the input voltage, and they can realize ZVS in a wide load range. The switches of the two-level leg sustain the input voltage, and they can realize

  19. A novel zero-voltage and zero-current-switching full-bridge PWM converter

    Microsoft Academic Search

    Xu Feng; Xu DianGuo; Liu YuXiu

    2003-01-01

    A novel zero voltage and zero current switching full bridge pulse width modulation (ZVZCS-FB-PWM) converter is proposed and analyzed. An auxiliary circuit, which consists of a diode and auxiliary winding coupled with output inductor, are added to provide zero current switching (ZCS) conditions. The ZCS of lagging-leg switches is achieved by resetting the primary current with induced EMF of auxiliary

  20. A novel zero-Voltage and zero-current-switching full-bridge PWM converter

    Microsoft Academic Search

    TingTing Song; Nianci Huang

    2005-01-01

    A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width modulation converter is proposed. The ZCS condition of the lagging-leg is obtained by a simple secondary auxiliary circuit resetting the primary current during the freewheeling stage. The auxiliary circuit's capacitor is charged by the center tape of the secondary through a diode, and the capacitor's voltage is clamped through another diode to

  1. Analysis and design of zero-voltage-switching current-fed isolated full-bridge Dc\\/Dc converter

    Microsoft Academic Search

    U R Prasanna; Akshay K Rathore

    2011-01-01

    This paper presents steady-state analysis and design of current-fed full-bridge dc\\/dc converter with active-clamp. The converter utilizes the energy stored in the transformer leakage, aided by its magnetizing inductance to maintain zero-voltage-switching of H-bridge switches over wide range of input voltage and load variation. Active-clamp clamps the voltage across the switches at turn-off, allowing the selection and use of low

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

    E-print Network

    Lehman, Brad

    advantages of cur- rent-fed topologies include immunity from transformer flux-im- balance and no output on all primary side power switches or soft switching properties when different driving schemes Terms--Current-fed, dc­dc converter, deadtime, dual-bridge, full-bridge, zero voltage switching (ZVS). I

  3. Phase-Shifted Full Bridge DC-DC Converter with Energy Recovery Clamp and Reduced Circulating Current

    Microsoft Academic Search

    Milan Ilic; Dragan Maksimovic

    2007-01-01

    This paper introduces a full bridge converter with reduced circulating current and a reduction of the switch conduction and turn-off losses achieved by an energy recovery secondary clamp circuit. The proposed clamp circuit allows the converter to operate with wide input or output voltage range with minimum voltage stress across the output diodes. The paper describes an experimental 25 kW

  4. Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter using a simple auxiliary circuit

    Microsoft Academic Search

    Jung G. Cho; Ju W. Baek; Chang Y. Jeong; Dong W. Yoo; Hong S. Lee; Geun H. Rim

    1998-01-01

    A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM power converter is presented to simplify the circuits of the previously presented ZVSCS power converters. A simple auxiliary circuit which consists of one small capacitor and two small diodes is added in the secondary to provide ZVZCS conditions to primary switches as well as to clamp secondary

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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.

  6. A Three-Level Full-Bridge Zero-Voltage Zero-Current Switching Converter With a Simplified Switching Scheme

    Microsoft Academic Search

    Joseph Alexander Carr; Brian Rowden; Juan Carlos Balda

    2009-01-01

    Multilevel DC-DC converters making use of high-frequency transformers are suitable for integration in solid-state solutions for applications in electric power distribution systems. This paper presents a simplified switching scheme for three-level full-bridge DC-DC converters that enables zero-voltage and zero-current switching of all the main power devices. It describes the main operational modes and design equations of the converter as well

  7. Study on optimum design procedure of charger based on full-bridge phase-shifted ZVZCS converter

    Microsoft Academic Search

    Niu Liyong; Jiang Jiuchun; Zhang Weige

    2008-01-01

    An optimum design procedure of an Electric Vehicle charger based on a full-bridge phase-shifted zero-voltage and zero-current switching (FB-PS-ZVZCS) dc-dc converter is proposed. The converter uses a small capacitor and two small diodes to form the clamp circuit, which makes the converter simple and easy to control. According to the analysis of the operation principles, several conclusions about the influences

  8. A fuzzy logic controller for half-bridge DC-DC PWM ZVZCS converter to high power applications

    Microsoft Academic Search

    H. R. De Azevedo; H. L. Hey; R. Paschoareli; R. C. Rende

    1993-01-01

    The authors propose a fuzzy controller applied for controlling a half-bridge DC-DC PWM zero-voltage zero-current switching converter'. The circuit operation follows the concept of lossless commutation. The authors present the analysis and simulation results for this converter, operating in closed-loop with fuzzy controller. The aim of the fuzzy logic controller is to control the output voltage of the converter so

  9. A Three-Level Full-Bridge Zero-Voltage Zero-Current Switching Converter With a Simplified Switching Scheme

    Microsoft Academic Search

    Joseph Carr; Brian Rowden; Juan Carlos Balda

    2007-01-01

    This paper presents a simplified switching scheme enabling zero-voltage and zero-current switching of all the main power devices of a three-level full-bridge dc-dc converter. It also describes the main operational modes and design equations of the converter. Simulation and experimental results demonstrate the feasibility of the proposed ideas. Multilevel dc-dc converters making use of high frequency transformers are suitable for

  10. Preventing transformer saturation in bi-directional dual active bridge buck-boost DC\\/DC converters

    Microsoft Academic Search

    Sangtaek Han; I. Munuswamy; D. Divan

    2010-01-01

    In switch-mode power electronic converters, DC offset of the magnetizing flux in the isolation transformer can cause saturation. In typical single-ended dc\\/dc converters, this is handled using a current loop which ensures that the average current in the winding is zero. For bi-directional dc\\/dc converters with active bridges on both sides, there exists a danger of impressing dc offsets from

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

    PubMed Central

    Tsai, Cheng-Tao; Tseng, Sheng-Yu

    2013-01-01

    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

  12. Bridges

    USGS Multimedia Gallery

    Bridges from top to bottom: Expressway Bridge, Liberty Memorial Bridge, Burlington Northern SantaFe Railway Bridge, and Interstate 94 Grant Marsh Bridge. Photo taken by USGS personnel on a Civil Air Patrol flight....

  13. A passive auxiliary circuit achieves zero-voltage-switching in full-bridge converter over entire conversion range

    Microsoft Academic Search

    Mangesh Borage; Sunil Tiwari; Swarna Kotaiah

    2005-01-01

    A passive auxiliary circuit is proposed to achieve zero-voltage-switching (ZVS) over the entire conversion range in a full-bridge (FB) pulse-width modulated (PWM) converter (FBZVS converter) with minimum conduction loss penalty. The stored energy in the auxiliary circuit is minimal under the full-load condition. It increases progressively as the load current decreases. The proposed auxiliary circuit is passive, simple and can

  14. Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter using transformer auxiliary winding

    Microsoft Academic Search

    Jung G. Cho; Ju W. Baek; D. W. Yoo; H. S. Lee; Geun H. Rim

    1997-01-01

    A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS

  15. Novel zero-voltage and zero-current-switching full bridge PWM converter using transformer auxiliary winding

    Microsoft Academic Search

    Jung-Goo Cho; Ju-Won Baek; Chang-Yong Jeong; Dong-Wook Yoo; Kee-Yeon Joe

    2000-01-01

    A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) pulse width modulation (PWM) converter is proposed to improve the demerits of the previously presented ZVZCS-FB-PWM converters, such as use of lossy components or additional active switches. A simple auxiliary circuit which includes neither lossy components nor active switches provides ZVZCS conditions to primary switches, ZVS for leading-leg

  16. Zero-voltage-zero-current switching in high-output-voltage full-bridge PWM converters using the interwinding capacitance

    Microsoft Academic Search

    Djordje Garabandic; William G. Dunford; Mark Edmunds

    1999-01-01

    A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulsewidth-modulated (PWM) power converter is proposed. The new converter uses the interwinding capacitance and a small primary-side inductor to achieve a zero-current-zero-voltage turn off and a zero-current turn on of the passive-to-active leg transistors. The turn off of the active-to-passive leg transistors is with zero voltage, and the turn on is with

  17. Zero-voltage-zero-current switching in high-output-voltage full bridge PWM converters using the interwinding capacitance

    Microsoft Academic Search

    Djordje Garabandic; W. G. Dunford; M. Edmunds

    1998-01-01

    A novel zero-voltage and zero-current switching (ZVZCS) full-bridge (FB) pulse width modulated (PWM) converter is proposed. The new converter uses the interwinding capacitance and a small primary side inductor to achieve a zero-current-zero-voltage turn off and a zero-current turn on of the passive-to-active leg transistors. The turn off of the active-to-passive leg transistors is with zero-voltage and the turn on

  18. Zero-voltage and zero-current-switching full-bridge PWM converter using secondary active clamp

    Microsoft Academic Search

    Jung-Goo Cho; Chang-Yong Jeong; Fred C. Y. Lee

    1998-01-01

    A new zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) pulse width modulation (PWM) power converter is proposed to improve the performance of the previously presented ZVZCS FB PWM power converters. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS (for leading-leg switches) and ZCS (for lagging-leg switches) are achieved without adding any lossy components or the saturable

  19. Zero-Voltage and Zero-Current Switching Full-Bridge DC–DC Converter With Auxiliary Transformer

    Microsoft Academic Search

    Jaroslav Dudrik; P. Spanik; N.-D. Trip

    2006-01-01

    A novel zero-voltage and zero-current switching (ZVZCS) full-bridge phase-shifted pulsewidth modulation (PWM) converter using insulated gate bipolar transistors (IGBTs) with auxiliary transformer is proposed to improve the properties of the previously presented converters. ZVZCS for all power switches is achieved for full load range from no-load to short circuit by adding active energy recovery snubber and auxiliary circuits. The principle

  20. ZVZCS Full-Bridge PWM DC\\/DC Converter using a Novel LCD Energy-Recovery Snubber

    Microsoft Academic Search

    Nam-In Kim; Gyu-Hyeong Cho

    2006-01-01

    The novel energy-recovery snubber (ERS) suitable for zero-voltage zero-current switching (ZVZCS) phase-shift full-bridge (PSFB) DC\\/DC converter is presented. The proposed ERS consists of an inductor, two capacitor and three diodes. With this LCD ERS, PSFB converter can achieve ZVZCS independent of various line and load conditions. The operation, features and analysis of this ERS are illustrated in this paper. Computer

  1. A zero-voltage and zero-current switching full bridge DC-DC converter with transformer isolation

    Microsoft Academic Search

    Seong-Jeub Jeon; Gyu-Hyeong Cho

    2001-01-01

    A new primary-side-assisted zero-voltage and zero-current switching full bridge DC-DC converter with transformer isolation is proposed. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to obtain ZCS for the leading leg. It has a simple and robust structure, and load current control capability even in short circuit conditions, The possibility of magnetic saturation due to asymmetricity

  2. Novel zero-voltage and zero-current-switching full-bridge PWM converter using a simple auxiliary circuit

    Microsoft Academic Search

    Jung-Goo Cho; Ju-Won Baek; Chang-Yong Jeong; Geun-Hie Rim

    1999-01-01

    A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulsewidth modulation converter is presented to simplify the circuits of the previously presented ZVSCS converters. A simple auxiliary circuit, which consists of one small capacitor and two small diodes, is added in the secondary to provide ZVZCS conditions to primary switches, as well as to clamp secondary rectifier voltage. The additional clamp circuit

  3. A Full-Bridge DC–DC Converter WithZero-Voltage-Switching Overthe Entire Conversion Range

    Microsoft Academic Search

    Mangesh Borage; Sunil Tiwari; Shubhendu Bhardwaj; Swarna Kotaiah

    2008-01-01

    A new topology of full-bridge dc-dc converter is proposed featuring zero-voltage-switching (ZVS) of active switches over the entire conversion range. In contrast to conventional techniques, the stored energy in the auxiliary inductor of the proposed converter is minimal under full-load condition and it progressively increases as the load current decreases. Therefore, the ZVS operation over the entire conversion range is

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

    SciTech Connect

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

    2009-05-07

    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.

  5. Novel zero-voltage and zero-current-switching (ZVZCS) full bridge PWM converter with low output current ripple

    Microsoft Academic Search

    J. W. Baek; C. Y. Jung; J. G. Cho; D. W. Yoo; G. H. Rim

    1997-01-01

    A novel zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter with low output current ripple is presented. A simple auxiliary circuit added in the secondary provides ZVZCS conditions to primary switches, ZVS for leading-leg switches and ZCS for lagging-leg switches, as well as reducing the output current ripple (ideally zero ripple). The auxiliary circuit includes neither

  6. Analysis and design of an auxiliary commutated full bridge DC\\/DC converter topology including the effect of leakage inductance

    Microsoft Academic Search

    Dheeraj K. Jain; Praveen K. Jain; Haibo Zhang

    2002-01-01

    This paper presents the analysis and design of an auxiliary commutated full bridge DC\\/DC converter topology including the effect of leakage inductance of the output transformer. In applications where the transformer has high turns-ratio between the primary and secondary windings, the value of leakage inductance is relatively high. This high value of leakage inductance, however, is not large enough to

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

    Microsoft Academic Search

    A. Jangwanitlert; J. C. Balda

    2004-01-01

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

  8. Modulation Extension Control of Hybrid Cascaded H-Bridge Multilevel Converters with 7-Level Fundamental Frequency Switching Scheme

    SciTech Connect

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

    2007-01-01

    This paper presents a modulation extension control algorithm for hybrid cascaded H-bridge multilevel converters. The hybrid cascaded H-bridge multilevel motor drive using only a single DC source for each phase is promising for high power motor drive applications since it can greatly decrease the number of required DC power supplies, has high quality output power due to its high number of output levels, and has high conversion efficiency and low thermal stress by using fundamental frequency switching scheme. But one disadvantage of the 7-level fundamental frequency switching scheme is that its modulation index range is too narrow when capacitor's voltage balance is maintained. The proposed modulation extension control algorithm can greatly increase capacitors' charging time and decrease the capacitors' discharging time by injecting triplen harmonics to extend the modulation index range of the hybrid cascaded H-bridge multilevel converters.

  9. A Three-Phase Single-Stage AC-DC Full Bridge Converter with High Power Factor and Phase-Shift PWM

    Microsoft Academic Search

    Dunisha Wijeratne; Gerry Moschopoulos

    2009-01-01

    Converters that integrate the functions of power factor correction (PFC) and isolated dc-dc conversion in a single power converter have been proposed to reduce the cost associated with operating two separate switch-mode converters. Many low power ac-dc single-stage converters have been proposed in the power electronics literature, but very few three-phase single-stage full-bridge converters and these require sophisticated methods of

  10. Bridges

    NSDL National Science Digital Library

    2012-07-19

    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.

  11. Method of controlling switching of a multiphase inductor-converter bridge

    DOEpatents

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

    1981-01-01

    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.

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

    Microsoft Academic Search

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

    2008-01-01

    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

  13. Applications of soft-switching full-bridge converter and rotational electric field to transdermal drug delivery

    Microsoft Academic Search

    T.-F. Wu; S.-Y. Tseng; D.-S. Su; Y.-M. Chen; Y.-K. Chen

    2004-01-01

    This paper presents applications of a soft-switching full-bridge converter to generate pulsed voltage (PV) for exciting tissue, which includes transdermal drug delivery (TDD), transcutaneous electrical nerve stimulation, functional electrical stimulation, etc. Particularly, in TDD it offers many potential advantages over conventional methods, such as oral and injection, and it avoids drug degradation through gastro-intestinal and liver. To design a portable

  14. An improved zero-voltage and zero-current-switching full-bridge PWM converter using a simple resonant circuit

    Microsoft Academic Search

    Kyoung-Wook Seok; Bong-Hwan Kwon

    2001-01-01

    An improved zero-voltage and zero-current-witching full-bridge pulsewidth modulation (ZVZCS-FB-PWM) DC-to-DC converter is presented and analyzed. An auxiliary resonant circuit, which consists of a switch and a capacitor, are added to provide zero-current switching (ZCS) conditions to the primary lagging-leg switches. Due to the auxiliary circuit, when the primary current is being extinguished, the voltage applied on the leakage inductance of

  15. An improved zero-voltage and zero-current-switching PWM full-bridge DC-DC converter

    Microsoft Academic Search

    A. Jangwanitlert; K. J. Olejniczak; J. C. Balda

    2003-01-01

    An improved isolated zero-voltage and zero-current switching full-bridge pulse width modulation (ZVZCS-FB-PWM) DC-DC converter having dual voltage outputs of 42 V and 5 V are presented. The leading leg achieves zero voltage switching, and the lagging leg with a series diode and active snubber circuit achieves zero current switching. A phase-shifted (PS) PWM technique is used to obtain ZVZCS by

  16. Zero-voltage and zero-current-switching PWM hybrid full-bridge three-level converter

    Microsoft Academic Search

    Xinbo Ruan; Bin Li

    2005-01-01

    This paper proposes a zero-voltage and zero-current-switching pulsewidth modulation hybrid full-bridge three-level (ZVZCS PWM H-FB TL) converter, which has a TL leg and a two-level leg. The voltage stress of the switches of the TL leg is half of the input voltage, and the switches can realize ZVS, so MOSFETs can be adopted; the voltage stress of the switches of

  17. Low Voltage and Current Stress ZVZCS Full Bridge DC–DC Converter Using Center Tapped Rectifier Reset

    Microsoft Academic Search

    Xinke Wu; Xiaogao Xie; Chen Zhao; Zhaoming Qian; Rongxiang Zhao

    2008-01-01

    An improved zero-voltage and zero-current-switching (ZVZCS) full bridge dc-dc converter is proposed based on phase shift control. With an auxiliary center tapped rectifier at the secondary side, an auxiliary voltage source is applied to reset the primary current of the transformer winding. Therefore, zero-voltage switching for the leading leg switches and zero-current switching for the lagging leg switches can be

  18. Bridges

    MedlinePLUS

    Bridges A bridge, also known as a fixed removable denture, is made to replace one or more missing teeth. Bridges can be supported in any of three ways: ... a combination of teeth and implants A traditional bridge is made by creating a crown for the ...

  19. A new soft switching high step-up converter

    Microsoft Academic Search

    M. Delshad; M. Zamani Sedeh

    2011-01-01

    In this paper a high step-up soft switching converter is presented. The proposed converter consists of a flyback transformer for increasing voltage gain and an active clamp circuit for providing ZVS conditions for all switches. In this converter the secondary of transformer is rectified by a voltage multiplier which is connected series with output and increase voltage gain of proposed

  20. Study and Implementation of a Current-Fed Full-Bridge Boost DC–DC Converter With Zero-Current Switching for High-Voltage Applications

    Microsoft Academic Search

    Ren-Yi Chen; Tsorng-Juu Liang; Jiann-Fuh Chen; Ray-Lee Lin; Kuo-Ching Tseng

    2008-01-01

    This paper presents a comprehensive study of a current-fed full-bridge boost dc-dc converter with zero-current switching (ZCS), based on the constant on-time control for high-voltage applications. The current-fed full-bridge boost converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. In order to achieve ZCS under a wide load range and with various input

  1. A Novel Soft-Commutating Isolated Boost Full-Bridge ZVS-PWM DC–DC Converter for Bidirectional High Power Applications

    Microsoft Academic Search

    Lizhi Zhu

    2006-01-01

    A soft-commutating method and control scheme for an isolated boost full bridge converter is proposed in this paper to implement dual operation of the well-known soft-switching full bridge dc\\/dc buck converter for bidirectional high power applications. It provides a unique commutation logic to minimize a mismatch between current in the current-fed inductor and current in the leakage inductance of the

  2. Operation principles of bi-directional full-bridge DC\\/DC converter with unified soft-switching scheme and soft-starting capability

    Microsoft Academic Search

    Kunrong Wang; Fred C. Lee; Jason Lai

    2000-01-01

    A new bi-directional dual full-bridge DC\\/DC converter with a unified soft-switching scheme and soft-start capability is proposed in this paper. A simple voltage clamp branch is used to limit transient voltage across the current-fed bridge and realize zero-voltage-switching (ZVS) in boost mode operation, while achieving hybrid zero-voltage\\/zero-current switching (ZVZCS) for the voltage-fed bridge in buck mode operation. The theory of

  3. Bridges

    NSDL National Science Digital Library

    Leske, Cavin.

    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.

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

    SciTech Connect

    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

    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.

  5. Waveform dependent switching losses in flyback transformer foil windings

    Microsoft Academic Search

    Doug Lavers; Eric Lavers

    2002-01-01

    The copper losses in a foil wound flyback transformer are examined using a time domain 2-D finite element model. The purpose of the study is to examine the losses as a function of switching waveform. It is shown that the windings carry nonnegligible induced current at times when the net current in the winding is zero. As with eddy current

  6. Bridges

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

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

  7. ZVS-ZCS full-bridge DC-DC converter for voltage step-up in fuel cell distributed generation systems

    Microsoft Academic Search

    R. Bojoi; G. Griva; G. Kovacevic; A. Tenconi

    2007-01-01

    This paper proposes a ZVS-ZCS full-bridge converter for voltage step-up applications, where only a few solutions have been proposed in the literature. A new auxiliary circuit is used on the high-voltage side of the proposed converter to achieve Zero Current Switching (ZCS) for one converter leg, while Zero Voltage Switching (ZVS) is achieved for the other leg by means of

  8. Feasibility study of half- and full-bridge isolated DC\\/DC converters in high-voltage high-power applications

    Microsoft Academic Search

    Dmitri Vinnikov; Tanel Jalakas; Mikhail Egorov

    2008-01-01

    This paper discusses the half- and full-bridge DC\\/DC converter topologies for high-power (200 kW) high-voltage (3.6 kV) applications. Focus is on the primary part of these topologies, i.e. the feasibility of replacement of two high-voltage IGBTs in the full-bridge by two high-voltage film capacitors in the half-bridge. The implementation of a half-bridge topology will lead to a sufficient simplification of

  9. Converter

    NSDL National Science Digital Library

    2010-01-01

    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.

  10. Ac-Ac Dual Active Bridge Converter for Solid State Transformer

    E-print Network

    Kimball, Jonathan W.

    converter topologies have been proposed for SST in literatures. A multi-stage ac-dc-ac-dc-ac SST scheme flow. The advantages of direct ac-ac conversion include fewer power conversion stages and minimized single-stage direct ac-ac power conversion to an SST. Fewer conversion stages reduce conduction loss

  11. Dual Liquid Flyback Booster for the Space Shuttle

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    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.

  12. Liquid flyback booster pre-phase: A study assessment

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  13. An improved full-bridge zero-voltage-transition PWM DC\\/DC converter with zero-voltage\\/zero-current switching of the auxiliary switches

    Microsoft Academic Search

    Dong-Yun Lee; Byoung-Kuk Lee; Dong-Seok Hyun

    1998-01-01

    In this paper, an improved full-bridge (FB) zero-voltage-transition (ZVT) PWM DC\\/DC power converter topology is proposed. The proposed FB-ZVT PWM DC\\/DC power converter has the advantage of achieving zero voltage and zero current switching of the auxiliary switches using an auxiliary network. The auxiliary network is simply composed of a saturable inductor, auxiliary capacitors and auxiliary diodes. With the help

  14. Design procedure and modeling of high power, high performance, zero-voltage zero-current switched, full-bridge PWM converter

    Microsoft Academic Search

    C. Cuadros; C. Y. Lin; D. Boyevich; R. Watson; G. Skutt; F. C. Lee; P. Ribardiere

    1997-01-01

    A general design procedure for the high power, high performance, zero-voltage zero-current switched full-bridge (ZVZCS-FB), PWM power converter is presented. Average and small-signal models of the power converter are developed. The former shows a decrease in loss of duty-cycle with increasing output power, whereas the latter reveals negative damping effects. Both effects are produced by the interaction between blocking capacitor

  15. A novel full-bridge zero-voltage-transition PWM DC\\/DC converter with zero-voltage\\/zero-current switching of the auxiliary switches

    Microsoft Academic Search

    Dong-Yun Lee; Byoung-Kuk Lee; Dong-Seok Hyun

    1998-01-01

    In this paper, a novel full-bridge (FB) zero-voltage-transition (ZVT) PWM DC\\/DC converter topology is proposed. The proposed FB-ZVT PWM DC\\/DC converter has ZVS of main switches for wide load and line ranges and an advantage of achieving zero voltage and zero current switching of the auxiliary switches using the auxiliary network. The auxiliary network is simply composed of saturable inductor,

  16. An improved full-bridge zero-voltage-transition PWM DC\\/DC converter with zero-voltage\\/zero-current switching of the auxiliary switches

    Microsoft Academic Search

    Dong-Yun Lee; Byoung-Kuk Lee; Sang-Bong Yoo; Dong-Seok Hyun

    2000-01-01

    In this paper, a novel full-bridge (FB) zero-voltage-transition (ZVT) pulsewidth modulation (PWM) DC\\/DC converter topology is proposed. The proposed FB-ZVT PWM DC\\/DC converter has zero-voltage switching (ZVS) of main switches for the entire line and load range and an advantage of achieving ZVS and zero-current switching of the auxiliary switches using the auxiliary network. The auxiliary network is simply composed

  17. Analysis of conducted EMI emissions on a soft-switched full bridge dc-dc converter with a fixed switching frequency

    Microsoft Academic Search

    A. Jangwanitlert; J. C. Balda; K. J. Olejniczak

    2003-01-01

    This paper presents a comparative study between a soft-switched full bridge DC-DC converter using phase-shifted pulse-width-modulation (PSFB-PWM) and another one with PWM control without phase-shifted strategy. The converter using phase-shifted control achieves zero-voltage and zero-current switching (ZVZCS), whereas the other without using phase-shifted control achieves ZVS. The paper describes the operating characteristics and analyzes the performance of both circuits, includes

  18. Novel zero-current switching current-fed half-bridge isolated Dc\\/Dc converter for fuel cell based applications

    Microsoft Academic Search

    Akshay K. Rathore; Sudip K. Mazumder

    2010-01-01

    This paper presents a novel zero-current switching (ZCS) current-fed half-bridge isolated dc\\/dc converter. It is a potential topology for front-end dc\\/dc power conversion for fuel cell inverters. This proposed converter is unique, not reported in literature and provides a simple solution to switch turn-off problem with ZCS without increase in components count. This will lead to reduced size, lower cost

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

    NASA Astrophysics Data System (ADS)

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

    1981-05-01

    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.

  20. Interleaved soft-switched active-clamped L–L type current-fed half-bridge DC–DC converter for fuel cell applications

    Microsoft Academic Search

    Akshay K. Rathore

    2009-01-01

    In this paper, an interleaved soft-switched active-clamped L–L type current-fed half-bridge isolated dc–dc converter has been proposed. The L–L type active-clamped current-fed converter is able to maintain zero-voltage switching (ZVS) of all switches for the complete operating range of wide fuel cell stack voltage variation at full load down to light load conditions. Active-clamped circuit absorbs the turn-off voltage spike

  1. An adaptive reconfigurable dc-dc converter for renewable energy applications

    Microsoft Academic Search

    Muhammad F. Zulfiqar; Mahmoud Alahmad

    2009-01-01

    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

  2. Modeling and Analysis of a Current-Fed ZCS Full-Bridge DC\\/DC Converter with Adaptive Soft-Switching Energy

    Microsoft Academic Search

    H. Wang; H. S. H. Chung; S. Tapuchi; A. Ioinovici

    2009-01-01

    A full dc and ac analysis of a previous proposed boost-type-input soft-switching full-bridge converter is presented. The primary-side switches turn-on\\/off under a zero-current condition (ZCS). The soft-switching is realized by using a simple snubber, formed by two uni-directional switches and a resonant capacitor, in the primary side. The snubber's switches commute under a zero-voltage condition. The resonant energy used for

  3. A class of zero-voltage-zero-current switching full bridge PWM converters with a parallel capacitor for primary current reset

    Microsoft Academic Search

    Djordje Garabandic; W. G. Dunford; M. Kuzmanovic

    1999-01-01

    This paper presents and analyses the principle of zero-voltage-zero-current switched phase shifted full-bridge DC\\/DC converters using the parallel capacitor. In principle, the parallel capacitance across the secondary terminals of the transformer and the primary side inductor (usually referred to as leakage inductor) are used to achieve a zero-current-zero-voltage turn off and a zero current turn on of the passive-to-active leg

  4. A novel zero-voltage and zero-current-switching PWM full-bridge converter using two diodes in series with the lagging leg

    Microsoft Academic Search

    Xinbo Ruan; Yangguang Yan

    2001-01-01

    This paper proposes a novel phase-shifted zero-voltage and zero-current-switching (ZVZCS) pulsewidth modulation full-bridge converter, which realizes ZVS for the leading leg and ZCS for the lagging leg. A blocking capacitor is added in series with the primary winding of the transformer to make the primary current decay to zero during zero state to ensure ZCS for the lagging leg. In

  5. Reusable, flyback liquid rocket booster for the Space Shuttle

    NASA Astrophysics Data System (ADS)

    Benton, Mark G.

    1989-08-01

    This paper outlines a preliminary design for an unmanned, reusable, flyback liquid rocket booster (LRB) as an evolutionary follow-on to the Shuttle solid rocket booster (SRB). Previous Shuttle liquid-propellant booster concepts are reviewed in order to gain insight into these designs. The operating costs, environmental impacts, and abort options of the SRB are discussed. The LRB flight profile and advantages of LRB use are discussed. The preliminary design for the LRB is outlined in detail using calculations and drawings. This design maximizes the use of existing hardware and proven technology to minimize cost and development time. The LRB design is presented as a more capable, more environmentally acceptable, and safer Shuttle booster.

  6. Analysis and Modeling of the ZVZCS Full Bridge PWM DC-DC Converter Using a Secondary Auxiliary Circuit

    Microsoft Academic Search

    Yang Xiaobo; Wu Weiyang; Shen Hong

    2005-01-01

    In this paper a novel ZVZCS FB-PWM DC\\/DC converter is analyzed. Comparing with the small signal models of the buck converter and the ZVS-FB PWM converter, the paper indicates that the characters of ZVZCS small signal model are significantly different from the latter. On the basis of small signal modeling, the compensation network is designed and verified by the simulation

  7. A novel high-efficiency flyback power-factor-correction circuit with regenerative clamping and soft switching

    Microsoft Academic Search

    Kam-Wah Siu; Yim-Shu Lee

    2000-01-01

    Although most power factor correction (PFC) circuits use the boost topology, the flyback topology does have the advantages of input-output isolation, inrush current limiting and voltage step-down capability. In this paper, the problems associated with flyback PFC circuits are identified. These problems are solved by using a novel regenerative clamping circuit. The circuit topology, analysis, design considerations and experimental results

  8. A Novel Zero-Voltage Zero-Current Switching Full-Bridge PWM Converter Using Improved Secondary Active Clamp

    Microsoft Academic Search

    Te-Fang Chen; Shu Cheng

    2006-01-01

    A novel FB-PS-ZVZCS converter is proposed. By turning on the clamping MOSFET during the primary current circulating period, this converter clamps the voltage of the output filter inductor to zero, so the voltage of the output filter capacitor is reflected to the primary and applied on the leakage inductance to quickly reset the primary circulating current. This new topology has

  9. Buck-boost converter with dual-mode control for battery charging

    Microsoft Academic Search

    1985-01-01

    A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode. These instabilities are avoided in

  10. Monolithic cascade device in low power converter applications with wide range input voltage

    Microsoft Academic Search

    S. Buonomo; C. Cavallaro; F. Chimento; S. Musumeci; A. Raciti; R. Scollo

    2006-01-01

    An improved converter for low power and wide range input voltage, which is particularly suitable for auxiliary uses in three-phase grid of industrial applications, is studied. A flyback quasi-resonant topology has been chosen, which offers the good characteristics of high voltage operations and good efficiency. A comparison is performed among available kinds of semiconductor devices with good peculiarities for the

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

    Microsoft Academic Search

    Wuhua Li; Xiangning He

    2008-01-01

    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

  12. Modeling, Analysis and Design of 15kW Zero-Voltage Zero-Current Switched Full Bridge PWM Converter

    Microsoft Academic Search

    Yimeng Shi; Guozhu Chen; Yulin Li

    2007-01-01

    This paper presents the modeling and design of a novel ZVZC FB-PWM converter. Compared to the traditional topology which employs a saturated inductor to block the reverse current in order to achieve ZCS for the lagging leg, a novel one using two diodes in series with the lagging leg is adopted. Both the duty ratio loss is reduced and the

  13. Simple time domain analysis of a five-level H-bridge Flying Capacitor converter voltage balancing

    Microsoft Academic Search

    Steven Thielemans; Alex Ruderman; Boris Reznikov; Jan Melkebeek

    2010-01-01

    Flying Capacitor (FC) multilevel Pulse Width Modulated (PWM) converters are an attractive choice due to the natural balancing property of the capacitor voltages. The balancing can be studied in the time domain, which results in easy to interpret expressions regarding parameter influence. Time domain analysis is normally done by time averaging of the system model over a PWM-period. In this

  14. Digital Bridges: Bridges of the Nineteenth Century

    NSDL National Science Digital Library

    2002-01-01

    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

  15. Progress on the 140kV 10Megawatt Peak, 1Megawatt Average Polyphase Quasiresonant Bridge, Boost Converter\\/Modulator for the Spallation Neutron Source (SNS) Klystron Power System

    Microsoft Academic Search

    William A. Reass; James D. Doss; Robert F. Gribble; Michael T. Lynch; Paul J. Tallerico

    2000-01-01

    This paper describes electrical design and operational characteristics of a zero-voltage-switching 20 kHz polyphase bridge, boost converter\\/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three \\

  16. Magnetorheological converters

    SciTech Connect

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

    1986-04-01

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

  17. Buck-boost converter with dual-mode control for battery charging

    SciTech Connect

    Ray, R. C.

    1985-08-20

    A voltage controlled flyback converter used as a battery charging circuit avoids the power dissipation of the more conventional series-type regulator-type charging circuits but cannot be readily utilized because of the high gain in the feedback loop due to the battery voltage, which causes instabilities therein when it is operated in a continuous current mode. These instabilities are avoided in a flyback converter used for battery charging by using current control techniques to control current on the primary side of the converter during high-rate battery charging. During low-rate charging, normal voltage feedback from an output current sensing resistor is used as long as the converter operates in a discontinuous mode.

  18. Interleaved power converter

    DOEpatents

    Zhu, Lizhi (Canton, MI)

    2007-11-13

    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.

  19. Multi Power Port Converter for Hybrid Electric Vehicles Using Multi Phase Bidirectional FlyBack Topology

    Microsoft Academic Search

    T. Bhattacharya; S. Giri V; K. Mathew; L. Umanand

    2006-01-01

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

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

    NASA Technical Reports Server (NTRS)

    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

    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.

  1. A novel full-bridge DC-DC converter for battery charging using secondary-side control combines soft switching over the full load range and low magnetics requirement

    Microsoft Academic Search

    Rajapandian Ayyanar; Ned Mohan

    2001-01-01

    A novel full-bridge DC-DC configuration with a tapped transformer and secondary side control is proposed. It achieves zero-voltage switching for the primary side switches and zero-current switching for the secondary side switches, under all operating conditions. The conduction losses are significantly lower than those in the conventional soft-switching DC-DC converters. Due to superior filter waveforms, the filter requirements, both at

  2. Power converters and amplifiers (review of \\

    Microsoft Academic Search

    Marian Kazmierkowski

    2009-01-01

    This book is a comprehensive textbook in the areas of electrical, electronics, and telecommunications engineering. It consists of 17 chapters and two appendices. Some of the topics covered include: buck PWM DC-DC converters; boost PWM DC-DC converters; buck-boost-PWM DC-DC converters; half-bridge and full-bridge converters; push-pull PWM DC-DC converters; open-loop small-signal characteristics of boost converters for CCM; current-mode control of boost

  3. High power density dc\\/dc converter: Selection of converter topology

    Microsoft Academic Search

    Deepakraj M. Divan

    1990-01-01

    The work involved in the identification and selection of a suitable converter topology is described. Three new dc\\/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC\\/DC Converter; Single Phase Dual Active Bridges DC\\/DC Converter; and Three Phase Dual Active Bridges DC\\/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each

  4. Integrated 0.9 V charge-control switching converter with self-biased current sensor

    Microsoft Academic Search

    Yat-Hei Lam; Wing-Hung Ki; Chi-Ying Tsui; Dongsheng Ma

    2004-01-01

    A charge-control non-inverting flyback converter that works in pseudo-continuous conduction mode is presented. Charge control is realized through the introduction of an integrated self-biased current sensor for fast response with a fully-matched structure for accuracy down to the mA range. The topology allows an output voltage of 1.2 V to be derived from a supply voltage of 1.5 V down

  5. 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.

  6. 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.

  7. Zero-voltage switching technique in dc/dc converters

    NASA Astrophysics Data System (ADS)

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

    1990-07-01

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

  8. High-speed 3T MR spectroscopic imaging of prostate with flyback echo-planar encoding.

    PubMed

    Chen, Albert P; Cunningham, Charles H; Ozturk-Isik, Esin; Xu, Duan; Hurd, Ralph E; Kelley, Douglas A C; Pauly, John M; Kurhanewicz, John; Nelson, Sarah J; Vigneron, Daniel B

    2007-06-01

    Prostate MR spectroscopic imaging (MRSI) at 3T may provide two-fold higher spatial resolution over 1.5T, but this can result in longer acquisition times to cover the entire gland using conventional phase-encoding. In this study, flyback echo-planar readout trajectories were incorporated into a Malcolm Levitt's composite-pulse decoupling sequence (MLEV)-point-resolved spectroscopy sequence (PRESS) to accelerate the acquisition of large array (16 x 16 x 8), high spatial (0.154 cm(3)) resolution MRSI data by eight-fold to just 8.5 minutes. Artifact free, high-quality MRSI data was obtained in nine prostate cancer patients. Easy data reconstruction and the robustness of the flyback echo-planar encoding make this technique particularly suitable for the clinical setting. The short acquisition time provided by this method reduces the 3T prostate MRI/MRSI exam time, allows longer repetition times, and/or allows the acquisition of additional MR acquisitions within the same exam. PMID:17520729

  9. Progress on the 140 KV, 10 Megawatt Peak, 1 Megawatt Average Polyphase Quasi-Resonant Bridge, Boost Converter/Modulator for the Spallation Neutron Source (SNS) Klystron Power System

    E-print Network

    Reass, W A; Gribble, R F; Lynch, M T; Tallerico, P J; Reass, William A.; Doss, James D.; Gribble, Robert F.; Lynch, Michael T.; Tallerico, Paul J.

    2000-01-01

    This paper describes electrical design and operational characteristics of a zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three "H-Bridge" IGBT switching networks are used to generate the polyphase 20 kHz transformers primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to ...

  10. New Phase Shift Modulated ZVS Full-Bridge DC\\/DC Converter with Minimized Auxiliary Current for Medium Power Fuel Cell Application

    Microsoft Academic Search

    Andrew J. Mason; Praveen K. Jain

    2005-01-01

    This paper presents a new DC\\/DC converter topology for low input voltage, medium power applications such as a 7.75 kW residential solid oxide fuel cell (SOFC). The proposed converter uses adaptive energy storage to minimize auxiliary circulating currents and maximize efficiency. It also has a simple topology and low component count. Analysis and a design process are presented. The proposed

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  12. A No DC-Gain Error Small-Signal Model for the Zero-Voltage-Switching Phase-Shift-Modulated Full-Bridge DC-DC Converter

    Microsoft Academic Search

    Cleber Zanatta; José Renes Pinheiro

    2006-01-01

    In this paper, an improved small-signal model for the zero-voltage-switching phase-shift-modulated full-bridge which eliminates the DC-gain errors of its line-to-output and control-to-output model transfer functions is presented. A DC-gain and a frequency response comparison among small-signal models are evaluated. The model presented here demonstrates to be accurate for different designs parameters, being it in a simple s-domain polynomial ratio form.

  13. Common-Duty-Ratio Control of Input-Series Output-Parallel Connected Phase-shift Full-Bridge DC–DC Converter Modules

    Microsoft Academic Search

    Jianjiang Shi; Jie Luo; Xiangning He

    2011-01-01

    Input-series output-parallel (ISOP)-connected con- verters allow the use of low-voltage and low-power converter mod- ules for high input-voltage and high-power applications. Further, the use of high-frequency, low-voltage MOSFETs, which are opti- mized for very low on-resistance, is enabled, resulting in lower con- duction losses and higher power density. In this paper, a common- duty-ratio control scheme is proposed for an

  14. Modeling, analysis and design of 10 kW parallel module zero-voltage zero-current switched full bridge PWM converter

    Microsoft Academic Search

    Hangseok Choi; J. W. Kim; J. H. Lee; B. H. Cho

    2000-01-01

    In this paper, the modeling and the design of the 10 kW parallel module converter are presented. Due to the high input voltage and power level, IGBTs are selected for the switching devices. The ZVZCS techniques enable the ZVZCS FB-PWM topology to operate at the switching frequency of 40 kHz, while maintaining an efficiency of over 94% at full load.

  15. Compressed sensing for resolution enhancement of hyperpolarized 13C flyback 3D-MRSI

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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.

  17. Booster Main Engine Selection Criteria for the Liquid Fly-Back Booster

    NASA Technical Reports Server (NTRS)

    Ryan, Richard M.; Rothschild, William J.; Christensen, David L.

    1998-01-01

    The Liquid Fly-Back Booster (LFBB) Program seeks to enhance the Space Shuttle system safety, performance and economy of operations through the use of an advanced, liquid propellant Booster Main Engine (BME). There are several viable BME candidates that could be suitable for this application. The objective of this study was to identify the key Criteria to be applied in selecting among these BME candidates. This study involved an assessment of influences on the overall LFBB utility due to variations in the candidate rocket-engines characteristics. This includes BME impacts on vehicle system weight, performance, design approaches, abort modes, margins of safety, engine-out operations, and maintenance and support concepts. Systems engineering analyses and trade studies were performed to identify the LFBB system level sensitivities to a wide variety of BME related parameters. This presentation summarizes these trade studies and the resulting findings of the LFBB design teams regarding the BME characteristics that most significantly affect the LFBB system. The resulting BME choice should offer the best combination of reliability, performance, reusability, robustness, cost, and risk for the LFBB program.

  18. Booster Main Engine Selection Criteria for the Liquid Fly-Back Booster

    NASA Technical Reports Server (NTRS)

    Ryan, Richard M.; Rothschild, William J.; Christensen, David L.

    1998-01-01

    The Liquid Fly-Back Booster (LFBB) Program seeks to enhance the Space Shuttle system safety performance and economy of operations through the use of an advanced, liquid propellant Booster Main Engine (BME). There are several viable BME candidates that could be suitable for this application. The objective of this study was to identify the key criteria to be applied in selecting among these BME candidates. This study involved an assessment of influences on the overall LFBB utility due to variations in the candidate rocket engines' characteristics. This includes BME impacts on vehicle system weight, perfortnance,design approaches, abort modes, margins of safety, engine-out operations, and maintenance and support concepts. Systems engineering analyses and trade studies were performed to identify the LFBB system level sensitivities to a wide variety of BME related parameters. This presentation summarizes these trade studies and the resulting findings of the LFBB design teams regarding the BME characteristics that most significantly affect the LFBB system. The resulting BME choice should offer the best combination of reliability, performance, reusability, robustness, cost, and risk for the LFBB program.

  19. Bridge permeameter

    DOEpatents

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

    1996-01-01

    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.

  20. Straw Bridges

    NSDL National Science Digital Library

    Museum of Science and Industry, Chicago

    2012-01-01

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

  1. Efficient Design in a DC to DC Converter Unit

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    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.

  2. Popsicle Bridge

    NSDL National Science Digital Library

    IEEE

    2013-08-30

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

  3. Spaghetti Bridge

    NSDL National Science Digital Library

    2012-06-23

    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.

  4. Bridge permeameter

    DOEpatents

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

    1996-08-13

    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.

  5. Designing Bridges

    NSDL National Science Digital Library

    2014-09-18

    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.

  6. Digital Bridges

    NSDL National Science Digital Library

    2002-01-01

    "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.

  7. Bookmark Converter

    NSDL National Science Digital Library

    Broding, Magnus.

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

  8. Spaghetti Bridge

    NSDL National Science Digital Library

    Worcester Polytechnic Institute

    2013-01-01

    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.

  9. Thermionic converter

    DOEpatents

    Fitzpatrick, G.O.

    1987-05-19

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

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

    Microsoft Academic Search

    Shweta Gautam; Anil Kumar Yadav; Rajesh Gupta

    2012-01-01

    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

  11. Straw Bridges

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    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!

  12. A Zero-Voltage-Switching DC–DC Converter With High Voltage Gain

    Microsoft Academic Search

    Hyun-Lark Do

    2011-01-01

    A zero-voltage-switching (ZVS) dc-dc converter with high voltage gain is proposed. It consists of a ZVS boost converter stage and a ZVS half-bridge converter stage and two stages are merged into a single stage. The ZVS boost converter stage pro- vides a continuous input current and ZVS operation of the power switches. The ZVS half-bridge converter stage provides a high

  13. A novel interleaved and isolated buck converter with high voltage ratio

    Microsoft Academic Search

    Huang-Hua Chiu; Ming-Fa Tsai; Chung-Shi Tseng; Shu-Yi Yen

    2010-01-01

    This paper presents a novel interleaved and isolated DC to DC buck converter with high voltage ratio. The converter consists of a half-bridge converter and a forward converter which are connected in parallel with a common load. As being one of interleaved DC to DC converters, it has smaller output current ripples within wide duty ratio, and it also has

  14. Thermionic converter

    DOEpatents

    Fitzpatrick, Gary O. (Livermore, CA)

    1987-05-19

    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.

  15. A PSR single-stage flyback LED driver with simple line regulation and quasi-resonant operation

    NASA Astrophysics Data System (ADS)

    Weidong, Nie; Zongguang, Yu; Haibing, Wang; Bin, Guo; Long, Teng; Lihang, Yang

    2014-08-01

    A single-stage flyback driving integrated circuit (IC) for light-emitting diodes (LEDs) is proposed. With an average primary-side current estimation and negative feedback networks, the driver operates in the boundary conduction mode (BCM), while the output current can be derived and regulated precisely. By means of a simple external resistor divider, a compensation voltage is produced on the ISEN pin during the turn-on period of the primary MOSFET to improve the line regulation performance. On the other hand, since the delay time between the time that the secondary diode current reaches zero and the turn-on time of the MOSFET can be automatically adjusted, the MOSFET can always turn on at the valley voltage even if the inductance of the primary winding varies with the output power, resulting in quasi-resonant switching for different primary inductances. The driving IC is fabricated in a Dongbu HiTek's 0.35 ?m bipolar-CMOS-DMOS process. An 18 W LED driver is finally built and tested. Results show that the driver has an average efficiency larger than 86%, a power factor larger than 0.97, and works under the universal input voltage (85-265 V) with the LED current variation within ±0.5%.

  16. Measurement Converter

    NSDL National Science Digital Library

    Many online calculators require a Java-capable browser. Here's one that doesn't, and will perform over 500 different unit conversions for distance, area, volume, mass, speed, temperature, pressure, energy, power, force, etc. And when you convert, say, 5 kilometers to miles, you not only get the conversion result, but a wealth of related measurements and sample conversions.

  17. Myocardial Bridge

    MedlinePLUS

    ... flow enough that myocardial ischemia develops, especially during exercise or when the heart is beating quickly. What are the symptoms? Up to one-third of patients with a myocardial bridge do not have any ...

  18. Bridging Anticoagulation

    MedlinePLUS

    ... dose regimen, for example, enoxaparin (Lovenox) 1 mg/kg twice daily, is often used in North America, ... allocated to receive bridging anticoagulation (dalteparin 100 IU/kg twice daily) or matching placebo when warfarin is ...

  19. Spaghetti Bridge

    NSDL National Science Digital Library

    2012-12-13

    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.

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

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.

    1990-01-01

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

  1. Bridged graphite oxide materials

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  2. Resonant converter topologies with three and four energy storage elements

    Microsoft Academic Search

    I. Batarseh

    1994-01-01

    Generalized half-bridge and full-bridge resonant converter topologies with two, three and four energy storage elements are presented. All possible circuit topologies for such converters under voltage\\/current driven and voltage\\/current sinks are discussed. Many of these topologies have not been investigated in open literature. Based on their circuit element connections and source and load excitation types, these topologies are classified into

  3. Paper Bridge

    NSDL National Science Digital Library

    2014-04-25

    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).

  4. The Belizean Bridge Activity.

    ERIC Educational Resources Information Center

    Murfin, Brian

    2000-01-01

    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)

  5. Bridge Inspector's Training Manual.

    ERIC Educational Resources Information Center

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

    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,…

  6. Bridge Building

    NSDL National Science Digital Library

    Twin Cities Public Television, Inc.

    2008-01-01

    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.

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

    Microsoft Academic Search

    Afshin Samadi; Shahrokh Farhangi

    2008-01-01

    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

  8. Bridge Builders

    NSDL National Science Digital Library

    2010-01-01

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

  9. A novel three-port bi-directional DC-DC converter

    Microsoft Academic Search

    Xie Jun; Zhang Xing; Zhang Chong-wei; Liu Sheng-yong

    2010-01-01

    Multi-port bidirectional DC-DC converters have attracted special interest in applications where multiple energy sources are used. In this paper, a three-port converter with two active full bridges, a active half bridge, and a three-winding high-frequency transformer is proposed. It uses a single power conversion stage with high-frequency link to control power flow between batteries, supercapacitors, and load. The converter has

  10. 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.

  11. An Evaluation of Two-Level and Three-Level Zero-Voltage Zero-Current Switching Converters

    Microsoft Academic Search

    A. Medury; J. Carr; C. Balda; H. A. Mantooth

    2007-01-01

    This paper presents a comparative evaluation of the two-level full-bridge zero-voltage zero-current switching (ZVZCS) converter and the three-level half-bridge ZVZCS converter. The paper analyzes the operation and soft-switching limits of both converters, compares them from a theoretical point of view, and presents an approach to optimize their designs. Experimental results are presented to illustrate the performance of both converters..

  12. 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.

  13. Buck Converter Animation

    NSDL National Science Digital Library

    This website from the Thayer School of Engineering at Dartmouth College features an animation of a buck converter. A buck converter is a step-down DC to DC converter. Its design is similar to the step-up boost converter, and like the boost converter it is a switched-mode power supply that uses two switches (a transistor and a diode), an inductor and a capacitor.

  14. Bridging the Gaps

    NSDL National Science Digital Library

    2014-09-18

    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 — tension and compression — 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.

  15. Switching Power Converter A/D Converters

    E-print Network

    " monitoring capable of measuring system performance and detecting faults or anomalies in the operation using A/D converters and the data is sent to a digital controller for processing. A system interface then displays processed data concerning the converter health status. Online Health Monitoring in Digitally

  16. Feasibility study for convertible engine torque converter

    NASA Technical Reports Server (NTRS)

    1985-01-01

    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.

  17. Open-loop approach to control a Modular Multilevel Frequency Converter

    Microsoft Academic Search

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

    2011-01-01

    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

  18. Bridging consent: from toll bridges to lift bridges?

    PubMed Central

    2011-01-01

    Background The ability to share human biological samples, associated data and results across disease-specific and population-based human research biobanks is becoming increasingly important for research into disease development and translation. Although informed consent often does not anticipate such cross-domain sharing, it is important to examine its plausibility. The purpose of this study was to explore the feasibility of bridging consent between disease-specific and population-based research. Comparative analyses of 1) current ethical and legal frameworks governing consent and 2) informed consent models found in disease-specific and population-based research were conducted. Discussion Ethical and legal frameworks governing consent dissuade cross-domain data sharing. Paradoxically, analysis of consent models for disease-specific and population-based research reveals such a high degree of similarity that bridging consent could be possible if additional information regarding bridging was incorporated into consent forms. We submit that bridging of consent could be supported if current trends endorsing a new interpretation of consent are adopted. To illustrate this we sketch potential bridging consent scenarios. Summary A bridging consent, respectful of the spirit of initial consent, is feasible and would require only small changes to the content of consents currently being used. Under a bridging consent approach, the initial data and samples collection can serve an identified research project as well as contribute to the creation of a resource for a range of other projects. PMID:21970509

  19. Evaluation of Conducted EMI Emissions on ZVZCS PWM dc-dc Converters with a Fixed Switching Frequency

    Microsoft Academic Search

    A. Jangwanitlert; J. Songboonkaew

    2005-01-01

    This paper presents a comparative study between a Zero-Voltage and Zero-Current Switching Full-Bridge (ZVZCS-FB) dc-dc converter and ZVZCS-Three-Level (TL) dc-dc converter. Both converters uses Phase-Shifted PulseWidth Modulation (PS-PWM) strategy. The paper describes the operating characteristics and analyzes the performance of both converters, includes a comparison of conducted ElectroMagnetic Interference (EMI) emissions from both converters, and provides experimental results that are

  20. Superconductive energy storage inductor-converter units for power systems

    Microsoft Academic Search

    H. A. Peterson; N. Mohan; R. W. Boom

    1975-01-01

    Large magnets with superconductive windings could serve to perform a power system function analogous to pumped storage hydro. A conventional Graetz bridge converter as used in dc transmission provides an ideal interface between the three-phase power system and the superconductive magnet or inductor. Such Inductor-Converter or I-C units, when properly controlled, provide significant power system benefits. Power reversibility is achievable

  1. Measurement: Converting Distances

    NSDL National Science Digital Library

    2006-01-01

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

  2. Concrete Bridges in Germany

    Microsoft Academic Search

    Konrad Zilch; Hermann Weiher; Mathias Riesemann

    This article gives an overview over the state of the art of concrete bridges in Germany. In addition to the presentation of actual bridges projects (e.g. winners of German bridge award) new trends in bridge construction and post-tensioning technology will be presented. One is prestressing by combining unbonded internal and external tendons which already had been realized at the pilot-projects

  3. Low nasal bridge

    MedlinePLUS

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

  4. Comparison of power converters for small-scale wind turbine operation

    Microsoft Academic Search

    M. Pathmanathan; C. Tang; W. L. Soong; N. Ertugrul

    2008-01-01

    Small-scale wind turbines commonly use AC\\/DC converters such as rectifiers, switched mode rectifiers (SMRs) and inverters. Another power converter, the semi-bridge SMR has been researched for automotive applications, and is utilised by a number of small-scale wind turbine manufacturers. This paper applies a novel modulation technique developed for automotive applications of the semi-bridge SMR for Lundell and interior permanent magnet

  5. Performance Evaluation of a Novel Hybrid Multipulse Rectifier for Utility Interface of Power Electronic Converters

    Microsoft Academic Search

    Luiz Carlos Gomes de Freitas; M. G. Simoes; Carlos Alberto Canesin

    2007-01-01

    This paper presents an improved analysis of a novel programmable power-factor-corrected-based hybrid multipulse power rectifier (PFC-HMPR) for utility interface of power electronic converters. The proposed hybrid multipulse rectifier is composed of an ordinary three-phase six-pulse diode-bridge rectifier (Graetz bridge) with a parallel connection of single-phase switched converters in each three-phase rectifier leg. In this paper, the authors present a complete

  6. A three-phase power electronic converter for grid integration of distributed generation

    Microsoft Academic Search

    D. Schulz; R. Fabis; R. E. Hanitsch

    2003-01-01

    We designed a flexible DSP-controlled three-phase power electronic converter for the integration of distributed energy generation into networks. The further increase of energy conversion from renewable energy sources demands a share of the conventional centralized grid control. This requires a fast and flexible control system. Our converter consists of two IGBT inverter bridges, a diode rectifier bridge and an IGBT-chopper.

  7. Rotorcraft convertible engine study

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  8. Bridging the Gap: Linking Simulation and Testing

    SciTech Connect

    Krajewski, Paul E.; Carsley, John; Stoudt, Mark R.; Hovanski, Yuri

    2012-09-01

    The Materials Genome Initiative (MGI) which is a key enabler for the Advanced Manufacturing Partnership, announced in 2011 by U.S. President Barack Obama, was established to accelerate the development and deployment of advanced materials. The MGI is driven by the need to "bridge the gap" between (I) experimental results and computational analysis to enable the rapid development and validation of new mateirals, and (II) the processes required to convert these materials into useable goods.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    Microsoft Academic Search

    Kirubakaran Dhandapani; Rama Reddy Sathi

    2011-01-01

    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

  11. Myocardial bridges: A review.

    PubMed

    Loukas, Marios; Von Kriegenbergh, Katrina; Gilkes, Mathangi; Tubbs, R Shane; Walker, Christi; Malaiyandi, Deepa; Anderson, Robert H

    2011-09-01

    Much has been written regarding the potential clinical significance of myocardial bridges. As such bridging is often seen in normal individuals, it is clear that not all arteries bridged by myocardial segments produce clinical symptoms thereby suggesting that this feature may simply be an anatomical variant. However, some authors who have considered these bridges as the cause of cardiac ischemia have suggested two potential mechanisms for their pathophysiology. The first is a phasic systolic compression of the bridged segment with persistent mid-to-late diastolic reduction in arterial diameter and the second proposes a reduction in arterial flow. Both mechanisms may contribute to a reduced reserve in coronary blood flow. In this review, we discuss the evidence that exists regarding myocardial bridging and the potential for bridging to cause myocardial ischemia. PMID:21751254

  12. Dc-To-Dc Converter Uses Reverse Conduction Of MOSFET's

    NASA Technical Reports Server (NTRS)

    Gruber, Robert P.; Gott, Robert W.

    1991-01-01

    In modified high-power, phase-controlled, full-bridge, pulse-width-modulated dc-to-dc converters, switching devices power metal oxide/semiconductor field-effect transistors (MOSFET's). Decreases dissipation of power during switching by eliminating approximately 0.7-V forward voltage drop in anti-parallel diodes. Energy-conversion efficiency increased.

  13. 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, Watergate & Bridge Plaza, Adjacent to Arlington Memorial Bridge & Lincoln Memorial, Washington, District of Columbia, DC

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

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

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

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

    Microsoft Academic Search

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

    2008-01-01

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

  16. Rapid bridge deck replacement

    E-print Network

    Osegueda, Roberto Alejandro

    1983-01-01

    . Background and Significant Work Purdue University-Indiana State Highway Corrnrission New York State Thruway Authority . . . . . . . . . . . . New York State Department of Transportation . Pennsylvania Turnpike Commission Interstate 80 Overpass, Oakland... York Thruway Authority 7 Roundout Creek Bridge Deck, Kingston, New York. New York State Department of Transportation 8 Delaware River Bridge, New York-Pennsylvania. New York State Department of Transportation 10 9 Erie County Bridge Deck...

  17. Wave-energy converter

    Microsoft Academic Search

    1985-01-01

    The invention provides a device for converting wave energy into useful work, and comprises a body adapted to be moved to and fro by waves on a liquid, and means such as a hydraulic piston in a cylinder for converting this movement of the body into a power output. The body may be disposed about a horizontal cable along which

  18. Wave-energy converter

    Microsoft Academic Search

    1982-01-01

    The invention provides a device for converting wave energy into useful work, and comprises a body adapted to be moved to and fro by waves on a liquid, and means such as a hydraulic piston in a cylinder for converting this movement of the body into a power output. The body may be disposed about a horizontal cable along which

  19. The microminiature thermionic converter

    Microsoft Academic Search

    Donald Bryan King

    2000-01-01

    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

  20. Semiconductor bridge (SCB) detonator

    DOEpatents

    Bickes, Jr., Robert W. (Albuquerque, NM); Grubelich, Mark C. (Albuquerque, NM)

    1999-01-01

    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 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.

  1. Semiconductor bridge (SCB) detonator

    DOEpatents

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

    1999-01-19

    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.

  2. Photocapacitive image converter

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  3. 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

  4. 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

  5. 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

  6. 4. View of bridge deck from northeast approach (bridge deck ...

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

    4. View of bridge deck from northeast approach (bridge deck from southwest approach is virtually identical - Big Cottonwood River Bridge No. 246, Spanning Big Cottonwood River at Cottonwood Street (City Road No. 165), New Ulm, Brown County, MN

  7. Design, modeling, and analysis of integrated magnetics for power converters

    Microsoft Academic Search

    David Ki-Wai Cheng; Leung-Pong Wong; Yim-Shu Lee

    2000-01-01

    Some guidelines on the synthesis of integrated magnetics are introduced. Potential problems of integrated magnetics are identified. PSpice models are developed for computer-aided analysis and design purposes. A boost-flyback SSIPP (single-stage isolated power-factor-corrected power supply) with regenerative clamping is used as an example circuit to verify the application and performance of integrated magnetics

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

    Microsoft Academic Search

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

    2004-01-01

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

  9. Constant switching frequency series resonant three-port bi-directional DC-DC converter

    Microsoft Academic Search

    H. Krishnaswami; N. Mohan

    2008-01-01

    Multi-port converters have attracted special interest in applications such as self sustaining residential homes and buildings with multiple energy sources and energy storage. In this paper a constant switching frequency series resonant three-port bi-directional DC-DC converter is proposed. The converter uses a three-winding transformer with two of its windings connected to H-bridges through series resonant circuits. To control the output

  10. Clamping for current-fed de\\/dc converters with recovery of clamping energy in fuel cell inverter systems

    Microsoft Academic Search

    Malte Mohr; Friedrich W. Fuchs

    2007-01-01

    Current-fed dc\\/dc converters like current-fed full bridge converters or boost converters with autotransformer, which are appropriate solutions in medium power fuel cell systems, need clamping circuits to protect the main semiconductors against overvoltages. Depending on the stray inductances of the inductive components the power drawn by the clamping circuit can be up to 5-10% of the converter's transferred power. This

  11. Zero-Voltage and Zero-Current-Switching PWM Combined Three-Level DC\\/DC Converter

    Microsoft Academic Search

    Fuxin Liu; Jiajia Yan; Xinbo Ruan

    2010-01-01

    This paper proposes a zero-voltage and zero-current-switching (ZVZCS) PWM combined three-level (TL) dc\\/dc converter, which is a combination of a ZVZCS PWM TL converter with a ZVZCS PWM full-bridge converter. The proposed converter has the following advantages: all power switches suffer only half of the input voltage; the voltage across the output filter is very close to the output voltage,

  12. Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

    Microsoft Academic Search

    Osman S. Senturk; Lars Helle; Stig Munk-Nielsen; Pedro Rodriguez; Remus Teodorescu

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter topological features and the simulation results demonstrating the converter performance, these three 3L-VSCs are discussed and compared in

  13. 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

  14. LODGEPOLE BRIDGE, FACING SOUTHEAST Generals Highway, Lodge Pole Bridge, ...

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

    LODGEPOLE BRIDGE, FACING SOUTHEAST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA

  15. LODGEPOLE BRIDGE, FACING NORTHWEST Generals Highway, Lodge Pole Bridge, ...

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

    LODGEPOLE BRIDGE, FACING NORTHWEST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA

  16. Microminiature thermionic converters

    DOEpatents

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

    2001-09-25

    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.

  17. Active-bridge oscillator

    DOEpatents

    Wessendorf, Kurt O. (Albuquerque, NM)

    2001-01-01

    An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.

  18. Bryce Canyon Natural Bridge

    USGS Multimedia Gallery

    The Bryce Canyon Natural Bridge. Technically, this is not a natural bridge, which forms when running water erodes a tunnel into a rock formation. Instead, this is a natural arch, similar to the ones in nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is...

  19. Bridge Program Planning Guide

    NSDL National Science Digital Library

    Jenkins, Davis

    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.

  20. 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....

  1. Analysis of land bridge transportation

    Microsoft Academic Search

    Yong Qi; Yan Wang

    1991-01-01

    Land bridge transportation means transportation from one seaport to another by railway across continents instead of by ocean\\u000a ship. At present, there are two common routes for using land bridge transportation in the world. One is Asia—America—Europe\\u000a land bridge, the other is Europe—Asia land bridge.\\u000a \\u000a Eurasia land bridge has obvious advantages over Asia—America—Europe land bridge due to its shorter distance,

  2. PDF to HTML Converter

    NSDL National Science Digital Library

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Circuit bridging of components by smoke

    SciTech Connect

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

    1996-10-01

    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.

  5. New dc rail side soft-switching PWM dc-dc converter with high frequency planar transformer

    Microsoft Academic Search

    Khairy Sayed; Keiki Morimoto; Soon-Kurl Kwon; Katsumi Nishida; Mutsuo Nakaoka

    2011-01-01

    This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type dc-dc high power converter for DC bus feeding power plants. The proposed dc-dc power converter is composed of typical voltage source-fed half- bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side

  6. Mineral bridges in nacre.

    PubMed

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

    2011-12-01

    We confirm with high-resolution techniques the existence of mineral bridges between superposed nacre tablets. In the towered nacre of both gastropods and the cephalopod Nautilus there are large bridges aligned along the tower axes, corresponding to gaps (150-200nm) in the interlamellar membranes. Gaps are produced by the interaction of the nascent tablets with a surface membrane that covers the nacre compartment. In the terraced nacre of bivalves bridges associated with elongated gaps in the interlamellar membrane (>100nm) have mainly been found at or close to the edges of superposed parental tablets. To explain this placement, we hypothesize that the interlamellar membrane breaks due to differences in osmotic pressure across it when the interlamellar space below becomes reduced at an advanced stage of calcification. In no cases are the minor connections between superimposed tablets (<60nm), earlier reported to be mineral bridges, found to be such. PMID:21982842

  7. The Königsberg Bridge Problem

    NSDL National Science Digital Library

    2011-01-01

    This article, written for middle grades students, relates the history of the famous Konigsberg Bridge problem and introduces the idea of networks and paths that do not retrace themselves. The article concludes with a path the student must work out.

  8. Implant-Supported Bridge

    MedlinePLUS

    ... made by the dental lab. Porcelain-fused-to-metal bridge The restoration (the part that looks like ... porcelain attached and fused to a framework of metal. The Implant Process The time it takes to ...

  9. Build Your Bridge

    NSDL National Science Digital Library

    These interactive learning modules and simulations allow students to explore the science, technology and people involved in building the New Bay Bridge, which is intended as a replacement for the historic San Francisco-Oakland Bay Bridge that was damaged in the 1989 Loma Prieta Earthquake. In the interactive module "Quake Country," students investigate plate tectonics as the driving force behind the faulting and resulting earthquakes in the Bay area. In the "Engineering for Earthquakes" simulation, students act as engineers, design their own bridges, and test them against the Maximum Credible Earthquake (MCE), the worst earthquake that might hit the Bay area every 1500 years. In the module "Two Miles and 2,000 Hands," students learn about the people who perform a large variety of jobs in building the new bridge.

  10. Design Squad: Suspension Bridge

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2007-08-09

    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.

  11. Vector generator scan converter

    DOEpatents

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

    1988-02-05

    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.

  12. Vector generator scan converter

    DOEpatents

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

    1990-01-01

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

  13. Woodrow Wilson Bridge Project

    Microsoft Academic Search

    2001-01-01

    A detailed 3D model was created to show the 500-million dollar construction project of a 10-mile section of I-95 at the Virginia \\/ Maryland Border, it includes four multi-level interchanges and a major bridge (Woodrow Wilson Bridge) across the Potomac River. Using AutoCAD Land evelopment and 3D Studio Max 3.1, a multi gigabyte 3D database was created to engineering accuracy.

  14. Bridge Rectifier Animation

    NSDL National Science Digital Library

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

  15. Bridging spinal cord injuries

    E-print Network

    2008-10-15

    ] describe a particular type of immature astrocyte that seems to provide a very successful bridging material. The idea of using embryonic CNS tissue and embryonic astrocytes for repairing the spinal cord has a long history. Axons grow in the embryonic CNS, so... at various mechanisms, including neutrali- zation of inhibitory molecules, promotion of plasticity, direct stimulation of axon regeneration, bridging and control of inflammation. A combination of two or more of these approaches will be needed to achieve...

  16. Metallurgical study of thermionic converters

    Microsoft Academic Search

    PETER ROUKLOVE

    1969-01-01

    This paper describes some of the observations made as a result of the test of 180 thermionic converters and of the postmortem metallographic examination of approximately 50 converters. The causes and effects of converter abnormal performance are related to the results of the metallographic examinations. The materials and fabrication methods utilized in converter construction are discussed together with areas of

  17. Dual switched mode power converter

    Microsoft Academic Search

    PALLAB MIDYA; FRED H. SCHLERETH

    1989-01-01

    A dual power converter is introduced which addresses the problem of output ripple and switching losses in a switched power converter. One stage of the power converter is a conventional PWM (pulse-width modulated) converter, and the other stage is a linear source. The linear source controls the voltage directly, and the output current of the linear stage is used to

  18. HEAT DIODE CONVERTER

    Microsoft Academic Search

    M. Gottlieb; R. J. Zollweg; L. S. Richardson; A. E. Fein; J. G. DeSteese

    1963-01-01

    Experimental and theoretical investigations were made on several aspects ; of the cesium plasma thermionic converter. Data were taken on the electron ; emission properties of tungsten, tantalum, molybdenum, niobium, rhenium, iridium, ; and tantalum carbide. Two methods were used in this study; one was the ; measurement of the I-V characteristics of diodes using eminers of these materials ;

  19. Catalytic Converters and Nanocatalysts

    NSDL National Science Digital Library

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

  20. Liquid metal thermal electric converter

    DOEpatents

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

    1989-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  2. Inductorless DC-AC Cascaded H-bridge Multilevel Boost Inverter for Electric/Hybrid Electric Vehicle

    E-print Network

    Tolbert, Leon M.

    - DC boost converter to boost the battery voltage for a traditional 3-phase inverter. The present HEV) and an H-bridge in series with each inverter leg which uses a capacitor as the DC power source. Fundamental that the proposed inductorless DC-AC cascaded H-bridge multilevel boost inverter can output a boosted AC voltage. I

  3. New control scheme for AC-DC-AC converter without DC link electrolytic capacitor

    Microsoft Academic Search

    J. S. Kim; S. K. Sul

    1993-01-01

    A novel concept for a static three-phase to three-phase power converter for an AC motor drive with unity power factor and reduced harmonics on the utility line is presented. The power circuit consists of two back-to-back connected six-pulse bridges having only a 5-?F ceramic capacitor in the DC link. By controlling the active power balance between two bridges, the DC

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

    Microsoft Academic Search

    Eun-Soo Kim; Yoon-Ho Kim

    2002-01-01

    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

  5. 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.

  6. Axionometric Cutaway of Bridge Structure Shoreham Railroad Bridge, Former ...

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

    Axionometric Cutaway of Bridge Structure - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT

  7. Shoreham Railroad Bridge, Title Sheet Shoreham Railroad Bridge, Former ...

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

    Shoreham Railroad Bridge, Title Sheet - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT

  8. `Smart bridge' technology helps monitor I-35W bridge behavior

    E-print Network

    Minnesota, University of

    the bridge's structural behavior in a project funded by the Minnesota Department of Transportation (MnDOT). During its construction, the bridge was instrumented with more than 500 sensors that monitor strain, load

  9. 4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ...

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

    4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ROAD OVER SOURIS RIVER NEAR SOUTH END OF REFUGE, LOOKING NORTHEAST - Upper Souris National Wildlife Refuge Dams, Souris River Basin, Foxholm, Ward County, ND

  10. 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

  11. 22. BRIDGE CREEK BRIDGE, AVENUE OF THE GIANTS, OLD HIGHWAY ...

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

    22. BRIDGE CREEK BRIDGE, AVENUE OF THE GIANTS, OLD HIGHWAY 101. HUMBOLDT COUNTY, CALIFORNIA. LOOKING E. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  12. Thermionic energy converters

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (inventor)

    1983-01-01

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

  13. Multilevel converters -- A new breed of power converters

    SciTech Connect

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

    1995-09-01

    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.

  14. Purplemath: Cancelling / Converting Units

    NSDL National Science Digital Library

    2009-08-14

    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.

  15. Advanced thermionic converter development

    Microsoft Academic Search

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

    1976-01-01

    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

  16. Free FLV Converter

    NSDL National Science Digital Library

    2007-01-01

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

  17. Thermionic energy converters

    SciTech Connect

    Morris, J.F.

    1983-02-08

    This invention is concerned with improving the efficiency of thermionic energy converters. The invention is particularly directed to the reduction of plasma losses in these converters. This beneficial technical effect is achieved by internal distribution of tiny shorted cesium diodes driven by the thermal gradient between the primary emitter and the collector. Specifically, the tiny, shorted diode distribution comprises protrusions of the emitter material from the main emitter face which contact the main collector face thermally but not electrically. The main collector ends of the protrusions are separated from the main collector by a thin layer of insulation, such as aluminum oxide. The diode effect will increase with the use of metals that adsorb cesium less readily for the main emitter ends of the tiny protrusions and metals that adsorb cesium more readily for the main collector ends of the protrusions. By way of example, the main emitter can be made of rhenium or irridium; the main emitter ends of the protrusions can be made of tantalum or niobium; and the main collector ends of the protrusions can be made of platinum or irridium. The shorted tiny diode distribution augments cesium ionization through internal thermal effects only within the main diode. No electrical inputs are required. This ionization enhancement by the distribution of the tiny shorted diodes not only reduces the plasma voltage drop but also increases the power output and efficiency of the overall thermionic energy converter.

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

    Microsoft Academic Search

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

    2011-01-01

    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.

  19. AC\\/DC\\/AC Converter Modulation Strategy With Natural Zero sequence Rejection Using Only One Six-Switch Inverter Module

    Microsoft Academic Search

    A. N. Velpuri; H. L. Hess; J. D. Law; E. J. Cegnar; E. Muljadi

    2007-01-01

    This paper reports an innovative power converter modulation strategy that converts energy from a poly-phase variable frequency source to a single-phase fixed frequency load using only one of the customary two six-switch bridge circuits characteristic of a dc link based power converter. To achieve this, a six-switch dc link CPRWM inverter is creatively modulated with two voltage components. The application

  20. Evaluating vehicular-induced bridge vibrations for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Reichenbach, Matthew; Fasl, Jeremiah; Samaras, Vasilis A.; Wood, Sharon; Helwig, Todd; Lindenberg, Richard

    2012-04-01

    Highway bridges are vital links in the transportation network in the United States. Identifying possible safety problems in the approximately 600,000 bridges across the country is generally accomplished through labor-intensive, visual inspections. Ongoing research sponsored by NIST seeks to improve inspection practices by providing real-time, continuous monitoring technology for steel bridges. A wireless sensor network with a service life of ten years that is powered by an integrated energy harvester is targeted. In order to achieve the target ten-year life for the monitoring system, novel approaches to energy harvesting for use in recharging batteries are investigated. Three main sources of energy are evaluated: (a) vibrational energy, (b) solar energy, and (c) wind energy. Assessing the energy produced from vehicular-induced vibrations and converted through electromagnetic induction is the focus of this paper. The goal of the study is to process acceleration data and analyze the vibrational response of steel bridges to moving truck loads. Through spectral analysis and harvester modeling, the feasibility of vibration-based energy harvesting for longterm monitoring can be assessed. The effects of bridge conditions, ambient temperature, truck traffic patterns, and harvester position on the power content of the vibrations are investigated. With sensor nodes continually recharged, the proposed real-time monitoring system will operate off the power grid, thus reducing life cycle costs and enhancing inspection practices for state DOTs. This paper will present the results of estimating the vibration energy of a steel bridge in Texas.

  1. 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

  2. 18. GRAYS RIVER BRIDGE PLAN, DATED 1905 (Original bridge plan ...

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

    18. GRAYS RIVER BRIDGE PLAN, DATED 1905 (Original bridge plan was lost after the plan was photographed.) this photograph is an 8x10-inch enlargement from a 4x5-inch negative) - Grays River Covered Bridge, Worrel Road spanning Grays River, Grays River, Wahkiakum County, WA

  3. Bridging Brown County Case Study Bridging Brown County Case Study

    E-print Network

    Minnesota, University of

    Bridging Brown County Case Study Bridging Brown County Case Study Connecting Communities Capacity 4 Collaboration 4 Networking 4 Community Vitality 4 Social Capital #12;Bridging Brown County Case, in 1998 a tornado caused severe damage in parts of the county. As Katie assisted groups and coordinated

  4. SBIR Phase II Bridge Award

    Cancer.gov

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

  5. Bridge Types: Tensile & Compressive Forces

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    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.

  6. 77 FR 16784 - General Bridge Regulation; Amendment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-22

    ...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...

  7. 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.

  8. Bridging the Generation Gap

    ERIC Educational Resources Information Center

    Johnson, Susan Moore; Kardos, Susan M.

    2005-01-01

    The lack of instructional continuity in schools negates every effort of principals to provide an environment where all students would be successful. One solution could be to bridge the gap between the professional knowledge and skills of experienced teachers and the energy and fresh ideas of new recruits so that the latter are provided support…

  9. Quantum Bidding in Bridge

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  10. Bryce Canyon Natural Bridge

    USGS Multimedia Gallery

    Bryce Canyon's Natural Bridge is technically a natural arch, similar to those in the nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates...

  11. Bridging the Gap?

    ERIC Educational Resources Information Center

    Salter, Colin

    2009-01-01

    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…

  12. CMOS Bridging Fault Detection

    Microsoft Academic Search

    Thomas M. Storey; Wojciech Maly

    1990-01-01

    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

  13. Long term bridge monitoring

    Microsoft Academic Search

    Jean Carracilli

    2001-01-01

    This study is based on the development and implementation of the REVE system, an acquisition system of traffic load effects over long periods, from one to several years. The objective is to measure, globally and experimentally, the dynamic effects of real road traffic by measuring strain extrema on a certain number of bridge construction details, using smart sensors networks. It

  14. URI Student Bridge

    Microsoft Academic Search

    Nicole Aragi

    2008-01-01

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

  15. Building Migratory Bridges

    ERIC Educational Resources Information Center

    Roy, Michael; Doss, Laurie K.

    2007-01-01

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

  16. Design Squad: Truss Bridge

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2007-08-09

    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.

  17. The Bridges Program.

    ERIC Educational Resources Information Center

    Bohnen, Elizabeth; Klie, Judy

    This report describes BRIDGES, an employment equity special measures training program developed by the City of Toronto (Ontario, Canada). It was designed to help women employees move from their traditional jobs into trades, technical or operation (TTO) jobs within their own organization. The program is a combination of classroom sessions, shop…

  18. USGS Gage At Covered Bridge

    USGS Multimedia Gallery

    This photograph shows Lowe's Bridge off ME-15 in Guilford, Maine, spanning the Piscataquis River. USGS gaging station 01031500 is located on the downstream side of the bridge. The original bridge, built in 1857, washed away in the flood of 1987, and was rebuilt on the original abutments in 1990....

  19. Schrodinger Bridges classical and quantum

    E-print Network

    system to a final probability distribution Yongxin Chen, Tryphon T. Georgiou, Michele Pavon #12;· History://arxiv.org/abs/1405.6650 Positive contraction mappings for classical and quantum Schrodinger systems Tryphon T of Schrodinger bridges · Bridges for Markov chains · The Hilbert metric · Bridges for quantum (TPTP) evolutions

  20. Voltage fed zero-voltage zero-current switching PWM DC-DC converter

    Microsoft Academic Search

    Jaroslav Dudrik; V. Ruscin

    2008-01-01

    A new zero-voltage zero-current switching full-bridge phase-shifted PWM converter with controlled output rectifier is presented in this paper. IGBT switches are used in the high-frequency inverter of the DC-DC converter. Zero-voltage turn-on and zero-current turn-off for all power switches of the inverter is achieved for full load range from no-load to short circuit by using new secondary energy recovery clamp

  1. A 1 megawatt polyphase boost converter-modulator for klystron pulse application

    Microsoft Academic Search

    W. A. Reass; J. D. Doss; R. F. Gribble

    2001-01-01

    This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter\\/modulator for klystron pulse application. The DC-DC converter derives the bus voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction

  2. A 1 megawatt polyphase boost converter-modulator for klystron pulse application

    Microsoft Academic Search

    W. A. Reass; J. D. Doss; R. F. Gribble

    2001-01-01

    Summary form only given, as follows. This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 10 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter\\/modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided

  3. A Three-Phase Bidirectional DC-DC Converter for Automotive Applications

    SciTech Connect

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL

    2008-01-01

    This paper presents a three-phase soft-switching, bidirectional dc-dc converter for high-power automotive applications. The converter employs dual three-phase active bridges and operates with a novel asymmetrical but fixed duty cycle for the top and bottom switches of each phase leg. Simulation and experimental data on a 6-kW prototype are included to verify the novel operating and power flow control principles.

  4. Cycloidal Wave Energy Converter

    SciTech Connect

    Stefan G. Siegel, Ph.D.

    2012-11-30

    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.

  5. The microminiature thermionic converter

    NASA Astrophysics Data System (ADS)

    King, Donald Bryan

    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 fabrication of the MTC uses micromachining and semiconductor integrated circuit fabrication methods. These fabrication techniques allow the MTC to have an inter-electrode spacing of 20 microns or less with electrode materials having work functions ranging from 0.75 to 3 eV. The small gap size and low work function features of the MTC give it the potential to produce electricity at relatively high conversion efficiencies (20--25%). MTC designs may be tailored to function for different heat sources (combustion, solar, advanced nuclear reactors, radioisotopes, waste heat) over broad temperature regimes. The MTC diode prototype has been successfully fabricated, operated, and analyzed over a wide range of emitter and collector temperatures in the power production mode as well as power consumption mode. The emitter temperatures of interest ranged from 770 through 1220K. Maximum power output densities of 2mW/cm2 have been produced, and maximum output voltages approaching 1 Volt have also been produced. The MTC has been used to power an external load consisting of a Motorola 1N4004 diode. Models have been developed to characterize thermionic surface emission and electron transport across the gap. The MTC diode current-voltage characteristics and features have been successfully modeled over all five operational modes that characterize a thermionic converter. Power production has not been as high as expected. The shortcomings are due to the low work function material, (Ba,Sr,Ca)O, used in the diode. The tests and models indicate that the irregularities in work function across the emission material are detrimental to power production that occurs at low voltage in all thermionic converters. Modest improvements in surface homogeneity could increase the power output density by at least three orders of magnitude.

  6. 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.

  7. 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.

  8. Reduction of voltage stress in the full bridge BIBRED by duty ratio and phase shift control

    Microsoft Academic Search

    M. A. Johnston; R. W. Erickson

    1994-01-01

    A new control scheme is presented which provides simultaneous control of the output voltage and the energy storage capacitor voltage in the full-bridge boost integrated with buck rectifier\\/energy storage\\/DC-DC power converter (full-bridge BIBRED). The new control scheme solves the problem of wide voltage excursions for the energy storage capacitor voltage under variable load conditions. A low frequency, large signal AC

  9. Cascaded H-Bridge Multilevel Boost Inverter without Inductors for Electric\\/Hybrid Electric Vehicle Applications

    Microsoft Academic Search

    S. Dhayanandh; A. P. Ramya Sri; S. Rajkumar; N. Lavanya

    \\u000a This paper presents a cascaded H-bridge multilevel boost inverter for electric vehicle (EV) and hybrid EV (HEV) applications\\u000a implemented without the use of inductors. Currently available power inverter systems for HEVs use a dc–dc boost converter\\u000a to boost the battery voltage for a traditional three-phase inverter. A cascaded H-bridge multilevel boost inverter design\\u000a for EV and HEV applications implemented without

  10. Bidirectional buck boost converter

    DOEpatents

    Esser, A.A.M.

    1998-03-31

    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.

  11. Gallium phosphide energy converters

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  12. Bidirectional buck boost converter

    DOEpatents

    Esser, Albert Andreas Maria (Niskayuna, NY)

    1998-03-31

    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.

  13. Climbing techniques for bridge inspection

    NASA Astrophysics Data System (ADS)

    Kaslan, Erol C.

    1998-03-01

    California has about 24,000 publicly owned bridges that require routine structural evaluations to comply with National Bridge Inspection Standard (NBIS) mandates. Of these, about 800 are identified as possessing fatigue prone or fracture critical details requiring thorough tactile investigations. Gaining access to bridge elements to perform these investigations has become increasingly difficult and costly. The traditional uses of under bridge inspection trucks, lift equipment and rigging are economically and practically limited by bridge size, structure type, traffic demands and support costs. In some cases, bridges that have become damaged by earthquakes cannot safely support the loads of heavy personnel lift equipment. The California Department of Transportation (Caltrans)'s Office of Structural Materials and Office of Structure Maintenance and Investigations evaluated the use of rock climbing and mountaineering techniques as an alternative means of gaining access for bridge inspections. Under a small research grant, a bridge climbing training course was developed through a local University of California outdoor recreation group and 7 engineers and technicians were initially trained. A comprehensive Code of Safe Practices was created and standards of training, procedures and equipment required for bridge inspections were established. A successful climb investigation on a large, previously inaccessible arch bridge was completed at the end of the training that proved the techniques safe, economical and effective. Within one year, 20 bridge maintenance engineers were trained, and a formal program was established to organize, schedule, equip and certify engineers and technicians for bridge climbing. Several other offices within Caltrans as well as the California Department of Water Resources have since adopted these techniques for specialized structural inspection tasks. Climbing techniques are now used routinely in California as an alterative means of gaining access to bridges and structures, and over 100 bridges have been identified as those where climbing is the only means available to perform structural investigations.

  14. Electrical Actuation Technology Bridging

    NASA Technical Reports Server (NTRS)

    Hammond, Monica (compiler); Sharkey, John (compiler)

    1993-01-01

    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.

  15. Bridging the Gap

    NSDL National Science Digital Library

    Grace Eason

    2004-11-01

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

  16. Build a Bridge

    NSDL National Science Digital Library

    2010-01-01

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

  17. Update in bridging anticoagulation

    Microsoft Academic Search

    Scott Kaatz; David Paje

    2011-01-01

    Patients treated with a vitamin K antagonist may require interruption of their anticoagulation prior to an invasive procedure\\u000a or surgery, and as a result, may be placed at a higher risk for thromboembolic events during this time. Either low-molecular-weight\\u000a heparin (LMWH) or unfractionated heparin is frequently used to bridge the gap in anticoagulation treatment because of their\\u000a relatively rapid onset

  18. Electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L. (inventor)

    1973-01-01

    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.

  19. Unity power factor converter

    NASA Technical Reports Server (NTRS)

    Wester, Gene W. (Inventor)

    1980-01-01

    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.

  20. Converting Biomass to Products

    SciTech Connect

    Graybeal, Judith W.

    2006-06-01

    For nearly 30 years, PNNL has been developing and applying novel thermal, chemical and biological processes to convert biomass to industrial and consumer products, fuels and energy. Honors for technologies resulting from this research include the Presidential Green Chemistry Award and several Federal Laboratory Consortium and R&D 100 Awards. PNNL’s research and development activities address the complete processing scheme, from feedstock pretreatment to purified product recovery. The laboratory applies fundamental science and advanced engineering capabilities to biomass conversion and processing to ensure effective recovery of optimal value from biomass; carbohydrate polymer systems to maximize energy efficiencies; and micro-technology systems for separation and conversion processes. For example, bioproducts researchers in the laboratory’s Institute for Interfacial Catalysis develop and demonstrate the utility of new catalyst formulations for production of bio-based chemicals. This article describes a sampling of current and recent catalysis projects for biomass conversion.

  1. High-Power Converters and AC Drives IEEE PESC2005 Tutorial

    E-print Network

    Wu, Bin

    Current Source Inverters 6. PWM Current Source Rectifiers 7. Voltage Source Inverter (VSI) Fed Drives 8 · Multilevel Voltage Source Inverters N dC Cascaded H-bridge (CHB) Inverter dC Two Level Inverter dC Flying. Current Source Inverter (CSI) Fed Drives Main Topics High-Power Converters and AC Drives Bin Wu 3 Topic 1

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

    SciTech Connect

    None

    2012-02-23

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

  3. Self-powered microthermionic converter

    DOEpatents

    Marshall, Albert C.; King, Donald B.; Zavadil, Kevin R.; Kravitz, Stanley H.; Tigges, Chris P.; Vawter, Gregory A.

    2004-08-10

    A self-powered microthermionic converter having an internal thermal power source integrated into the microthermionic converter. These converters can have high energy-conversion efficiencies over a range of operating temperatures. Microengineering techniques are used to manufacture the converter. The utilization of an internal thermal power source increases potential for mobility and incorporation into small devices. High energy efficiency is obtained by utilization of micron-scale interelectrode gap spacing. Alpha-particle emitting radioisotopes can be used for the internal thermal power source, such as curium and polonium isotopes.

  4. Tacoma Narrows Bridge: Extreme History

    NSDL National Science Digital Library

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

  5. The active-bridge oscillator

    SciTech Connect

    Wessendorf, K.O.

    1998-07-01

    This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is ab ridge-type oscillator design that is easly to design and overcomes many of the operational and design difficulties associated with standard bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. for this and other reasons, bridge oscilaltors are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator.

  6. The Adaptive Use Bridge Project

    NSDL National Science Digital Library

    University of Massachusetts, Amherst

    The Adaptive Use Bridge Project website is a repository for work being conducted at the University of Massachusetts, Amherst, in which historic iron bridges are rehabilitated, documented, and analyzed. The purpose of the project is to preserve the civil engineering heritage of New England and to develop instructional material for use in undergraduate civil engineering curricula. Upon completion of this long-term project, a protocol for adaptive pedestrian use of historic bridges will be created.

  7. BRIDGE: Briefings on Development & Gender

    NSDL National Science Digital Library

    BRIDGE (briefings on development and gender) is an information service provided by the Institute of Development Studies (IDS) at the University of Sussex. BRIDGE supplies development agencies with briefings that "present state of the art research findings, review current policy debates, synthesize best practice, and evaluate strategies for translating gender policies into practice." This site includes full-text BRIDGE publications, a bibliographic database, and links to other gender and development resources.

  8. 47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  9. 47 CFR 80.331 - Bridge-to-bridge communication procedure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  10. 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

  11. West Point Bridge Design Contest

    NSDL National Science Digital Library

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

  12. West Point Bridge Design Contest

    NSDL National Science Digital Library

    2003-01-01

    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.

  13. Nasal Bridge Intramuscular Hemangioma

    PubMed Central

    Hamir Basah, Zulkifli; Ramza Ramli, Ramiza; Gayadh, Maha Khadum; Mutum, Samarendra Singh

    2015-01-01

    Intramuscular haemangioma (IMH) is a benign mesenchymal tumour. It appears as a deep, nontender mass within the soft tissue, particularly in the extremities. This tumour may not be obvious on clinical examination. Head and neck IMHs represent only 13.5% of the total IMHs. The most common site for a head and neck IMH is the masseter muscle, followed by trapezius, sternocleidomastoid, and very rarely temporalis muscle. We present a patient with left nasal bridge swelling which was excised and histologically confirmed as intramuscular hemangioma. PMID:25709848

  14. Strengthen a Paper Bridge

    NSDL National Science Digital Library

    Twin Cities Public Television, Inc.

    2006-01-01

    In this quick activity (page 1 of the PDF), learners will test how many pennies a flat paper index card bridging the gap between two stacks of books is able to support. Then, learners alter the structure of the same card by folding it accordion-style and retest by again stacking pennies on top. Learners look for a relationship between the number of folds and the number of pennies the card can hold by creating a scatter plot. Relates to the linked video, DragonflyTV: Tug O’ War.

  15. Virtual Bridge Design

    NSDL National Science Digital Library

    Bobby JeanPierre

    2008-09-01

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

  16. Extended bridge algorithms for large networks

    Microsoft Academic Search

    W. D. Sincoskie; C. J. Cotton

    1988-01-01

    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.

  17. ZVZCS, dual, two-transistor forward DC-DC converter with peak voltage of Vin\\/2, high input and high power application

    Microsoft Academic Search

    Dharmraj V. Ghodke; K. Muralikrishnan

    2002-01-01

    This paper presents a zero voltage and zero current switching (ZVZCS), dual, two-transistor forward converter (DTTFC) for high input voltage and high power application. Two identical two-transistor forward converters (TTFC) are connected in series and coupled through a single transformer using two primary windings, because of which it operates like a full bridge and makes it suitable for high power

  18. Proposed electromagnetic wave energy converter

    NASA Technical Reports Server (NTRS)

    Bailey, R. L.

    1973-01-01

    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.

  19. Matrix converters: a technology review

    Microsoft Academic Search

    Patrick W. Wheeler; José Rodríguez; Jon C. Clare; Lee Empringham; Alejandro Weinstein

    2002-01-01

    The matrix converter is an array of controlled semiconductor switches that connects directly the three-phase source to the three-phase load. This converter has several attractive features that have been investigated in the last two decades. In the last few years, an increase in research work has been observed, bringing this topology closer to the industrial application. This paper presents the

  20. 49 CFR 236.713 - Bridge, movable.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  1. 33 CFR 115.40 - Bridge repairs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  2. Hybrid Cascaded H-bridges Multilevel Motor Drive Control for Electric Vehicles

    E-print Network

    Tolbert, Leon M.

    Hybrid Cascaded H-bridges Multilevel Motor Drive Control for Electric Vehicles Zhong Du1 , Leon M for electric/hybrid electric vehicles where each phase of a three-phase cascaded multilevel converter can vehicle motor drive applications and hybrid electric vehicle motor drive applications. Keywords: hybrid

  3. An integrated high power factor three-phase AC-DC-AC converter for AC-machines implemented in one microcontroller

    Microsoft Academic Search

    Frede Blaabjerg; John K. Pedersen

    1993-01-01

    A high power factor three-phase AC-DC-AC power converter for AC machines has been designed and tested. The AC-DC-AC converter is controlled by one single 16-b microcontroller. The converter has two PWM-VSI bridges with common snubber- and drive-circuit topologies. The high power factor rectifier is space vector controlled and the inverter controls an AC-induction machine by an energy optimized strategy. Common

  4. Burning trees and bridges

    NASA Technical Reports Server (NTRS)

    Levine, Joel S.

    1990-01-01

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

  5. Bridging the Watershed

    NSDL National Science Digital Library

    Bridging the Watershed (BTW) is an outreach program of the Alice Ferguson Foundation in partnership with the National Park Service and area schools. It promotes national parks as learning laboratories and provides a model that can be replicated in other parks and watersheds. The program is based in the Washington, D.C. metropolitan area. BTW partners share a fundamental goal to educate the public about the Potomac River and Chesapeake Bay watersheds in order to heighten awareness and develop stewardship for these resources. Science curriculum modules have been developed for high school students studying Earth science, chemistry, and the life sciences. Each module is composed of performance-based activities in which students examine and analyze the health of their watershed by applying science, math, problem-solving and action skills. Students gather authentic data to assess and problem solve real-world issues in the parks and watershed.

  6. 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.

  7. CRIME BULLETIN INCIDENT: Catalytic Converter Thefts

    E-print Network

    Barrett, Jeffrey A.

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

  8. OPERATIONAL RESULTS OF THE SPALLATION NEUTRON SOURCE (SNS) POLYPHASE CONVERTER-MODULATOR FOR THE 140 KV KLYSTRON RF SYSTEMS

    Microsoft Academic Search

    W. A. REASS; J. D. DOSS

    2001-01-01

    This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three

  9. Converting Petroleum Coke to Electricity

    E-print Network

    Pavone, A.

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

  10. Wind/water energy converter

    NASA Technical Reports Server (NTRS)

    Paulkovich, J.

    1979-01-01

    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.

  11. Transformerless dc-Isolated Converter

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.

    1987-01-01

    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.

  12. 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)

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

    1991-01-01

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

  13. 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)

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

    1991-01-01

    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.

  14. Binary/BCD-to-ASCII data converter

    NASA Technical Reports Server (NTRS)

    Miller, A. J.

    1977-01-01

    Converter inputs multiple precision binary words, converts data to multiple precision binary-coded decimal, and routes data back to computer. Converter base can be readily changed without need for new gate structure for each base changeover.

  15. 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...

  16. Mineral bridges in nacre revisited

    E-print Network

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

    2012-07-20

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

  17. Bridges.org

    NSDL National Science Digital Library

    Bridges.org is "an international non-profit organisation that promotes the effective use of Information and communications technology (ICT) in the developing world to reduce poverty and improve people's lives." The focus of its work involves ICT-related policy analysis, but organization "also promote best practice in ground-level technology implementation through research and evaluations." It provides information and resources, support grassroots projects and other efforts, and advise decision-makers and the public on key issues. As members of the technology community, the organization brings "an entrepreneurial attitude" and an understanding of technology as well as its commitment to work with governments and the private sector to achieve the goal of "spanning the international digital divide." The website provides an overview of the "digital divide" and describes the organization's approach to addressing these issues. Policy reports, case studies and evaluation guidelines are posted on this website. The organization's current work includes a comparison study of open source and proprietary software, which is also described here.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  19. BRIDGES IN VIBRATED GRANULAR MEDIA

    Microsoft Academic Search

    Anita Mehta

    We study a particular consequence of the dynamics of vibrated granular media, which is the spontaneous formation of stable\\u000a bridges. Here we examine their geometrical characteristics, and compare the results of a simple theory with those of independent\\u000a simulations of three-dimensional hard spheres. Our conclusion is that bridges are the signatures of spatiotemporal inhomogeneities,\\u000a the carriers of the so-called ‘force

  20. Development of Inspection Robots for Bridge Cables

    PubMed Central

    Kim, Se-Hoon; Lee, Jong-Jae

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Suskis, P.; Rankis, I.

    2012-01-01

    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.

  2. Power Flow Characterization of a Bidirectional Galvanically Isolated High-Power DC\\/DC Converter Over a Wide Operating Range

    Microsoft Academic Search

    Yanhui Xie; Jing Sun; James S. Freudenberg

    2010-01-01

    This paper studies the power flow characterization of a bidirectional galvanically isolated high-power dual active bridge DC\\/DC converter. In experimental tests at the University of Michigan, we have observed three phenomena, which we term as internal power transfer, phase drift, and low system efficiency, that are present under certain operating conditions. These phenomena cannot be explained by conventional power transfer

  3. A Comparison of Zero-Voltage and Zero-Current Switching Phase-Shifted PWM DC-DC Converters

    Microsoft Academic Search

    A. Jangwanitlert; J. Songboonkaew

    2005-01-01

    This paper presents a comparative study between an improved full-bridge (FB) zero-voltage and zero-current switching (ZVZCS) phase-shifted pulsewidth modulation (PS-PWM) DC-DC converter and an improved three-level (TL) ZVZCS PS-PWM DC-DC converter. Both converters operate at fixed frequency and achieve zero-voltage-switching on the leading leg of FB or outer switches of TL, and also achieve zero-current-switching on lagging leg of FB

  4. A Novel Prototype of Auxiliary Edge Resonant Bridge Leg-Link Snubber-Assisted Soft-Switching Sinewave PWM Inverter

    Microsoft Academic Search

    Mantaro Nakamura; Takayuki Yamazaki; Yuma Fujii; Tarek Ahmed; Mutsuo Nakaoka

    2004-01-01

    This paper proposes a new circuit topology of the three-phase soft switching PWM inverter and PFC converter using IGBT power modules, which has the improved active auxiliary switch and edge resonant bridge leg-commutation-link soft-switching snubber circuit with pulse current regenerative feedback loop as compared with the typical auxiliary resonant pole snubber discussed previously. This three-phase soft switching PWM double converter

  5. The Geography of European Convertible Bonds: Why Firms Issue Convertibles?

    E-print Network

    Saskatchewan, University of

    the global convertible market, suggesting that country-specific factors may play an important role in the use share of about 40% of the global market whereas most other countries have experienced dramatic changes to about 25% of the global market by the end of 2005. Why CBs find a more conducive growth environment

  6. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  7. A thermionic converter success story

    SciTech Connect

    Donovan, B.D.; Lamp, T.R. (Aerospace Power Division, Wright Laboratory Wright-Patterson AFB, OH 45433-6563 (United States)); Ramaligam, M.L. (UES, Inc. 4401 Dayton-Xenia Road, Dayton, OH 45432-1894 (United States))

    1993-01-20

    This paper summarizes the advanced out-of-core thermionic technology program being managed at Wright Laboratory: The Thermionic Critical Technology (TCT) Investigation. This program has been supported primarily by the United State Air Force for design and fabrication, and supported by Strategic Defense Initiative Organization (SDIO) for performance and life testing efforts. Converter design parameters, specifications, and performance testing data is summarized. Converters fabricated by Loral Electro Optical Systems (Loral EOS) under this program have exceeding performance requirements, and have demonstrated efficiencies as high as 14%.

  8. 49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  9. Current sharing in multiphase ZVT boost converter

    Microsoft Academic Search

    Esther de Jódar; José A. Villarejo; Jacinto Jiménez; Miguel Moreno

    2010-01-01

    Paralleling converters is a good choice for designing high frequency and high power converters. Nevertheless there must be a mechanism to share the load among phases to achieve all the benefits of parallel operation. A simple method to achieve current sharing is paralleling converters with high impedance. The ZVT Boost converter has interesting properties: Zero Voltage Transition, less semiconductors stress

  10. Damping assembly for a torque converter clutch

    Microsoft Academic Search

    Dull

    1989-01-01

    This patent describes a turbine damped torque converter and clutch. It comprises: a pressure plate; a torque converter turbine; a torque converter impeller; means including a control chamber for the pressure plate means for controlling the apply and release of the clutch for engaging the clutch with the impeller; a torque converter output shaft; a planetary gear arrangement including an

  11. Multilevel converters for power system applications

    SciTech Connect

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

    1995-09-01

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

  12. High-power converters for space applications

    NASA Technical Reports Server (NTRS)

    Park, J. N.; Cooper, Randy

    1991-01-01

    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.

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

    Microsoft Academic Search

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

    1987-01-01

    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

  14. Online partial discharge measurement of a high-voltage direct current converter wall-bushing

    Microsoft Academic Search

    N. D. Jacob; W. M. McDermid; B. Kordi

    2010-01-01

    An online Partial Discharge (PD) measurement performed on a High Voltage Direct Current (HVDC) wall bushing successfully identified the presence of internal discharges. The wall bushing is a sulfur hexafluoride gas-insulated bushing, rated for 500kVdc and terminated on a thyristor controlled HVDC converter bridge. The measurement of PD within the HVDC station environment is particularly challenging due to the high

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

    Microsoft Academic Search

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

    2007-01-01

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

  16. A novel integrated AC choke for common-mode voltage suppression in power converter systems

    Microsoft Academic Search

    Ning Zhu; Jinsong Kang; Dewei Xu; Bin Wu; Yuan Xiao

    2011-01-01

    This paper presents a novel three-phase choke that integrates the common-mode (CM) suppression and differential- mode (DM) filtering functions. The proposed choke provides a transformerless solution to issues caused by the switching common-mode voltage (CMV) in power converter systems. The magnetic core involves three bridge legs and a peripheral part on which one set (three-phase) of coils are wound. While

  17. Weigh-in-motion and smart bridges

    NASA Astrophysics Data System (ADS)

    Lai, Leon L.

    1997-05-01

    The bridge Weigh-In-Motion (WIM) system uses bridge structures as weigh scales to measure axle and gross vehicle weights and vehicle configurations without stopping or detouring the vehicles. Because the system is mobile and is almost invisible to the truck drivers, it can be used to collect unbiased traffic data for transportation and loadometer study. The WIM + RESPONSE system, which is an expansion of the original WIM system, was developed to collect additional bridge response data and perform bridge structural evaluation. These additional bridge response data provide bridge engineers with information necessary for improving bridge design and evaluation procedures. Bridge health monitoring and damage detection may also be conducted with long term installation of the WIM + RESPONSE system. This paper discusses what has been achieved by the WIM + RESPONSE system and how the system can be further improved to enhance its functions in a smart bridge.

  18. Hybrid-mode thermionic converter

    NASA Technical Reports Server (NTRS)

    Rasor, N. S.; Britt, E. J.

    1976-01-01

    Converter's collector electrode has uniform low work-function surface and operates at sufficiently low temperature to produce negligible electron emission. Emitter electrode has main region which has intermediate work-function and auxiliary region which has relatively high work-function surface.

  19. Converting Work into College Credits

    ERIC Educational Resources Information Center

    Hoffman, Joseph A.

    1976-01-01

    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.…

  20. Direct Drive Wave Energy Converters

    Microsoft Academic Search

    N. J. Baker; M. A. Mueller

    2001-01-01

    Over the last 25 years there have been numerous proposals for the conversion of energy contained within sea waves into electricity. Despite this fact, there is not yet one definitive wave energy device that stands out from the rest and developments in several concepts still continues. One aspect of a wave energy converter is the manner in which the physical

  1. Charge-pump voltage converter

    DOEpatents

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

    2009-11-03

    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.

  2. Parametric study of laser photovoltaic energy converters

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  3. A strange bridge by Leonardo

    E-print Network

    Huylebrouck, Dirk

    2013-01-01

    On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum col...

  4. 23 CFR 650.307 - Bridge inspection organization.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...

  5. 23 CFR 650.307 - Bridge inspection organization.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...

  6. 23 CFR 650.409 - Evaluation of bridge inventory.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...

  7. 23 CFR 650.307 - Bridge inspection organization.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...

  8. 23 CFR 650.409 - Evaluation of bridge inventory.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...

  9. 23 CFR 650.307 - Bridge inspection organization.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...

  10. 23 CFR 650.409 - Evaluation of bridge inventory.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...

  11. 23 CFR 650.409 - Evaluation of bridge inventory.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...

  12. 23 CFR 650.409 - Evaluation of bridge inventory.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program § 650.409 Evaluation of bridge inventory. (a)...

  13. 23 CFR 650.307 - Bridge inspection organization.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards § 650.307 Bridge inspection organization. (a) Each State...

  14. Construction Technologies: Create the Strongest Bridge

    NSDL National Science Digital Library

    K-12 Outreach Office,

    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.

  15. Bridge Decomposition of Restriction Measures

    NASA Astrophysics Data System (ADS)

    Alberts, Tom; Duminil-Copin, Hugo

    2010-08-01

    Motivated by Kesten's bridge decomposition for two-dimensional self-avoiding walks in the upper half plane, we show that the conjectured scaling limit of the half-plane SAW, the SLE(8/3) process, also has an appropriately defined bridge decomposition. This continuum decomposition turns out to entirely be a consequence of the restriction property of SLE(8/3), and as a result can be generalized to the wider class of restriction measures. Specifically we show that the restriction hulls with index less than one can be decomposed into a Poisson Point Process of irreducible bridges in a way that is similar to Itô's excursion decomposition of a Brownian motion according to its zeros.

  16. Bridge Decomposition of Restriction Measures

    E-print Network

    Tom Alberts; Hugo Duminil-Copin

    2010-07-03

    Motivated by Kesten's bridge decomposition for two-dimensional self-avoiding walks in the upper half plane, we show that the conjectured scaling limit of the half-plane SAW, the SLE(8/3) process, also has an appropriately defined bridge decomposition. This continuum decomposition turns out to entirely be a consequence of the restriction property of SLE(8/3), and as a result can be generalized to the wider class of restriction measures. Specifically we show that the restriction hulls with index less than one can be decomposed into a Poisson Point Process of irreducible bridges in a way that is similar to Ito's excursion decomposition of a Brownian motion according to its zeros.

  17. Balanced bridge feedback control system

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J. (inventor)

    1990-01-01

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

  18. Local scour at bridge abutments

    USGS Publications Warehouse

    Froehlich, David C.

    1989-01-01

    Comparison of local scour depths at bridge abutments computed using different equations yields a large variation in predicted values. To consolidate the fragmented results of previous investigations and assemble the most comprehensive data set possible, reported laboratory measurements of local scour at the end of an obstruction protruding from the side of an open channel of rectangular cross section were compiled from several sources. Regression analysis of these data was used to develop an equation that predicts maximum relative depth of local scour at bridge abutments for both clear-water and live-bed scour conditions.

  19. Excitation Methods for Bridge Structures

    SciTech Connect

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

    1999-02-08

    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.

  20. 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...

  1. Improved power regenerative controls by using thyristor rectifier bridge of voltage source inverter and a switching transistor

    Microsoft Academic Search

    K. Matsui; U. Mizuno; Y. Murai

    1992-01-01

    A few improved techniques of regenerative control for the voltage source inverter are described. In the proposed equipment, the thyristor rectifier bridge can be also utilized for regeneration through a DC reactor or capacitor. For the first converter mentioned, a novel pulse-width-modulated (PWM) strategy is proposed in which the polarity of the sawtooth carrier waveforms is reversed alternately at every

  2. Portable convertible blast effects shield

    DOEpatents

    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

    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.

  3. Portable convertible blast effects shield

    DOEpatents

    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

    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.

  4. Portable convertible blast effects shield

    DOEpatents

    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

    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.

  5. Microenergy Converter Using Insect Wings

    Microsoft Academic Search

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

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

  6. Modular packaging of VSCF converters

    NASA Astrophysics Data System (ADS)

    Pollard, David D.

    1987-10-01

    The use of modular building blocks to configure VSCF converters of ratings varying from 40 to 110 kVA with an unvarying geometry for uniform circuit impedances is demonstrated. The various modules are described and means of implementating rating changes are considered. Alternate cooling methods such as air and oil are discussed and a description is given of the physical adjustments necessary for cooling compatibility. Weight, size, and efficiency data are provided for all ratings and cooling methods.

  7. 75 FR 41281 - Bridge Safety Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-15

    ...bridges. The evaluation of a bridge requires...conduct regular comprehensive inspections of...might begin a comprehensive inspection and evaluation of a large structure...necessary for a comprehensive evaluation and...

  8. Wind effect on long span bridge

    E-print Network

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

    2012-01-01

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

  9. Overweight permit formulas for simply supported bridges

    E-print Network

    Mattox, Michael Joseph

    1992-01-01

    operational moments will not cause failure, the loads allowed will do more long term damage to the bridge than inventory values. Therefore, the lifetime of a bridge will be shortened if repeated loadings based on operational values pass over it...

  10. High efficiency thermionic converter studies

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    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.

  11. 1. NORTH HAMMA HAMMA BRIDGE LOOKING SOUTH THROUGH PORTALS OF ...

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

    1. NORTH HAMMA HAMMA BRIDGE LOOKING SOUTH THROUGH PORTALS OF BOTH THE NORTH AND SOUTH BRIDGES - North Hamma Hamma River Bridge, Spanning Hamma Hamma River Bridge at U.S. Route 101, Eldon, Mason County, WA

  12. 33 CFR 118.90 - Bridges crossing channel obliquely.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

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

  13. 49 CFR 237.103 - Bridge inspection procedures.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 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...

  14. 49 CFR 237.107 - Conduct of bridge inspections.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  15. 49 CFR 237.71 - Determination of bridge load capacities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...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...

  16. 49 CFR 237.109 - Bridge inspection records.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 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...

  17. 49 CFR 237.53 - Railroad bridge inspectors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  18. 49 CFR 237.111 - Review of bridge inspection reports.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  19. 23 CFR 650.809 - Movable span bridges.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...

  20. 23 CFR 650.809 - Movable span bridges.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...

  1. 23 CFR 650.809 - Movable span bridges.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...

  2. 23 CFR 650.809 - Movable span bridges.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...

  3. 23 CFR 650.809 - Movable span bridges.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge shall be selected wherever...

  4. 28. Under ninth bridge, view to concrete dam and eighth ...

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

    28. Under ninth bridge, view to concrete dam and eighth bridge in background during heavy rain, view to the SW. - Vicksburg National Military Park Roads & Bridges, Melan Arch Bridges, Spanning various tributaries at Confederate Avenue, Vicksburg, Warren County, MS

  5. Low Head, Vortex Induced Vibrations River Energy Converter

    SciTech Connect

    Bernitsas, Michael B.; Dritz, Tad

    2006-06-30

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

  6. A Multicell Converter Model of DBD Plasma Discharges

    SciTech Connect

    Flores-Fuentes, A. A.; Piedad-Beneitez, A. de la [Instituto Tecnologico de Toluca, AP 890, Toluca (Mexico); Pena-Eguiluz, R.; Mercado-Cabrera, A.; Valencia A, R.; Barocio, S. R. [Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, Mexico D.F. (Mexico); Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Benitez-Read, J. S.; Pacheco-Sotelo, J. O. [Instituto Tecnologico de Toluca, AP 890, Toluca (Mexico); Instituto Nacional de Investigaciones Nucleares, AP 18-1027, 11801, Mexico D.F. (Mexico)

    2006-12-04

    A compact Matlab model of plasma discharges in a DBD reactor consisting of two parallel electrode plates with a small gap and a thin dielectric sheet between them is reported. Its DBD plasma is modelled as a voltage controlled current-source switched on when the voltage across the gap exceeds the breakdown voltage. A three cell voltage-source inverter, configured in half-bridge, has been used as a power supply. This configuration has an excellent performance when operating as an open-loop. The distribution of total energy between a large number of low power converters proofs to be advantageous, allowing an efficient high power drive. Simulation results show that the current source and its output current tend to follow an exponential behaviour. A phenomenological characteristic of the voltage-current behaviour of DBD is then described by power laws with different voltage exponent function values.

  7. Utilizing zero-sequence switchings for reversible converters

    DOEpatents

    Hsu, John S.; Su, Gui-Jia; Adams, Donald J.; Nagashima, James M.; Stancu, Constantin; Carlson, Douglas S.; Smith, Gregory S.

    2004-12-14

    A method for providing additional dc inputs or outputs (49, 59) from a dc-to-ac inverter (10) for controlling motor loads (60) comprises deriving zero-sequence components (V.sub.ao, V.sub.bo, and V.sub.co) from the inverter (10) through additional circuit branches with power switching devices (23, 44, 46), transforming the voltage between a high voltage and a low voltage using a transformer or motor (42, 50), converting the low voltage between ac and dc using a rectifier (41, 51) or an H-bridge (61), and providing at least one low voltage dc input or output (49, 59). The transformation of the ac voltage may be either single phase or three phase. Where less than a 100% duty cycle is acceptable, a two-phase modulation of the switching signals controlling the inverter (10) reduces switching losses in the inverter (10). A plurality of circuits for carrying out the invention are also disclosed.

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

    ERIC Educational Resources Information Center

    Taylor, J. L.; Harmon, T.

    2010-01-01

    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…

  9. 47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  10. 47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  11. FEM analysis of vehicle-bridge vibration considering bridge deck's vibration

    Microsoft Academic Search

    Yong Ding; Shuqing Kong; Jianyuan Huang; Xu Xie

    2010-01-01

    This paper is to analyze the vehicle-bridge interaction system based on finite element method (FEM). The vehicle is studied as FEM model as well as the bridge: the bridge structure modeled by shell element considering the bridge deck's vibration, and the vehicle is also modeled by FEM. The coupling effect is implemented by displacement coordination condition and Newmark-? method is

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

    E-print Network

    Kareem, Ahsan

    , Wind load, Bridge, Random vibration. INTRODUCTION The estimation of wind induced buffeting responseNONLINEAR AERODYNAMIC ANALYSIS OF BRIDGES UNDER TURBULENT WINDS: THE NEW FRONTIER IN BRIDGE. In this study, a time domain analysis framework for predicting the flutter and buffeting responses of bridges

  13. Bridge building and bridge conservation in agreement with the genius loci

    Microsoft Academic Search

    Dirk Bühler

    Bridges ideally stand for the convergence of engineering landmarks and aesthetical attractions. But what's even more: bridges can be signs that reveal their meaning only by means of a skilful integration to their surrounding landscape or urban context. The appreciation of the spirit of place where bridge building happens is a substantial part for successful bridge design. The paper includes

  14. A Bridge to the Future

    ERIC Educational Resources Information Center

    Anderson, Richard

    2008-01-01

    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…

  15. Timber bridge ruins, not passable.

    E-print Network

    , sandstone, mudstone, and shale of the Lambert Shale, and San Lorenzo and Purisma Formations. Tertiary Basalt. Fractured, weathered lava flows and shallow intrusives of the Mindego Basalt. Veins of calcite and quartz over basalt. Qf Qs Qt Qc Tb Ts House. Rip rap revetment. Concrete wall. Geogrid. Bridge or crossing

  16. Bridges on the River Quad

    NSDL National Science Digital Library

    2012-08-30

    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 calculators’ 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.

  17. BRIDGING ACADEMIA, PRACTICE, LAW AND

    E-print Network

    Martin, Ralph R.

    INSIDE BRIDGING ACADEMIA, PRACTICE, LAW AND POLICY - MISSION CRITICAL FOR THE IISTL Page 2 team of experts from academia, industry and legal practice and provided a platform for its members figure both in legal practice and academia. On individual level, the members of the IISTL remain

  18. The Bridge School: A Profile.

    ERIC Educational Resources Information Center

    Sementelli, Catherine

    2001-01-01

    At the Bridge School (Hillsborough, California), children with severe speech and physical disabilities are trained in the use of augmentative and alternative communication technologies, transitioned back to their home school districts, and given continuing support. Outreach and research endeavors keep the broader community informed and educated…

  19. Building Cultural Bridges. Research Brief

    ERIC Educational Resources Information Center

    Burton, Ella

    2007-01-01

    The book "Building Cultural Bridges" is designed to increase multi-cultural awareness and sensitivity. There are supplemental materials available that include a leader's guide, reproducible student workbook, readings, worksheets, and activities. This material is recommended for use with students in grades 7-12. The materials included with this…

  20. Percentage Problems in Bridging Courses

    ERIC Educational Resources Information Center

    Kachapova, Farida; Kachapov, Ilias

    2012-01-01

    Research on teaching high school mathematics shows that the topic of percentages often causes learning difficulties. This article describes a method of teaching percentages that the authors used in university bridging courses. In this method, the information from a word problem about percentages is presented in a two-way table. Such a table gives…

  1. Bridging steady states with renormalization group analysis

    E-print Network

    Li, Charles

    Outline Bridging steady states with renormalization group analysis Yueheng Lan Department of Physics Tsinghua University April, 2013 Yueheng Lan Bridging steady states with RG analysis #12;Outline Yueheng Lan Bridging steady states with RG analysis #12;Outline Main contents 1 Introduction Physics

  2. Remediation: Higher Education's Bridge to Nowhere

    ERIC Educational Resources Information Center

    Complete College America, 2012

    2012-01-01

    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…

  3. Stability of connected cylindrical liquid bridges.

    PubMed

    Patel, Neha M; Dodge, Mohammad Reza; Alexander, J Iwan D; Slobozhanin, Lev A; Taylor, P L; Rosenblatt, Charles

    2002-02-01

    Two cylindrical liquid bridges, with a conduit to facilitate flow of liquid from one bridge to the other, were levitated against gravity in a magnetic field gradient. The stability limit of the bridges subjected to near zero total body force was measured as a function of their slenderness ratios, and found to be in good agreement with theoretical predictions. PMID:11863652

  4. The breaking of axisymmetric slender liquid bridges

    Microsoft Academic Search

    J. Meseguer

    1983-01-01

    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

  5. Building Bridges One Line at a Time

    ERIC Educational Resources Information Center

    Grigsby, Cathy Murray

    2012-01-01

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

  6. TAYLOR BRIDGE -FIELD ASSESSMENT Doug STEWARTi

    E-print Network

    system used to reduce the data collected from the bridge into engineering information which can be used as reinforcement and prestessing tendons, the bridge is I Wardrop Engineering Inc., Winnipeg, Manitoba, Canada R3CTAYLOR BRIDGE - FIELD ASSESSMENT Doug STEWARTi , Emile SHEHATAi , Gamil TADROS2 and Sami RIZKALLA2

  7. Removal of failed crown and bridge

    PubMed Central

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

    2012-01-01

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

  8. Canonical forms for cycles in bridge graphs

    Microsoft Academic Search

    S. Gill Williamson

    1993-01-01

    Let G = (V,E) be a biconnected graph and let C be a cycle in G. The subgraphs of G identified with the biconnected components of the contraction of C in G are called the bridges of C. Associated with the set of bridges of a cycle C is an auxilliary graphical structure GC called a bridge graph or an

  9. Removal of failed crown and bridge.

    PubMed

    Sharma, Ashu; Rahul, G R; Poduval, Soorya T; Shetty, Karunakar

    2012-07-01

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

  10. The capacitively coupled converter (C³) for high power DC-DC conversion

    E-print Network

    Khan, Shahriar

    1992-01-01

    at all times resulting in a very small resistive loss. At switch Si, the switching-off is done at close to zero voltage and therefore the switching losses are negligible even without the reasoning given above. 12 CONSTRAINTS ON CIRCUIT COMPONENTS... resistance St = switch at input Sq ? switch at output Vci ? voltage across flyback capacitor Vsi ? voltage across input switch Capital letters usually indicate the use of dc values (with exceptions). Small letters indicate variable values. 18 A...

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

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A.

    1994-01-01

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

  12. Large wind energy converter: Growian 3 MW

    NASA Technical Reports Server (NTRS)

    Koerber, F.; Thiele, H. A.

    1979-01-01

    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.

  13. Air-bridge high-speed InGaAs/InP waveguide photodiode

    NASA Astrophysics Data System (ADS)

    Yang, H.; Daunt, C. L. L. M.; Han, W.; Thomas, K.; Corbett, B.; Peters, F. H.

    2012-04-01

    The photodiode (PD) is a key component in optical transmission and optical measurement systems which receive optical signals and convert them into electric signals. High speed, high responsivity, high power and low dark current are desirable attributes of the PD in these applications, but also a simple fabrication process for high yield and low cost is essential for industry production. In this paper, an undercut-air-bridge high speed InGaAs/InP PIN structural photodiode is presented. By utilizing the crystal orientation dependent wet etching of InP material and designing the arms of the bridge with proper angle, the air bridge was easily obtained, which greatly eased the fabrication. The fabricated devices with 120?m×3?m ridge waveguides work robustly up to 30GHz in the measurements and potentially faster with optimized material.

  14. Chaos theory analysis of cable-stayed bridge vibration

    Microsoft Academic Search

    Richard A. Livingston; Shuang Jin

    2006-01-01

    Cable-stayed bridges are a recent development in bridge structural design in which the cables meet the bridge deck at an acute angle rather than perpendicularly. Some early cable-stayed bridges have exhibited large amplitude stay cable oscillations. One such bridge, the Fred Hartman Bridge across the Houston Ship Channel in Texas displayed two different modes of vibration: a local mode involving

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

    SciTech Connect

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

    2008-09-25

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

  16. Method for Controlling a Multilevel Cascade BTB System Using Bidirectional Isolated DC/DC Converters

    NASA Astrophysics Data System (ADS)

    Kitada, Ryohei; Akagi, Hirofumi

    This paper discusses a 6.6-kV next-generation BTB system in which bidirectional isolated dc/dc converters are combined with modular multilevel cascade converters. The system consists of N converter cells cascaded in each phase at both front ends. Each converter cell consists of a bidirectional isolated dc/dc converter and two voltage-source H-bridge PWM converters. This circuit configuration can be adopted to significantly reduce harmonic voltages and currents because the voltage steps are extremely low. In a conventional power conversion system, bulky line-frequency transformers are employed. On the other hand, in the present system, light and compact high-frequency transformers are used for providing galvanic isolation. Thus, the overall physical size and weight are reduced. The authors design, construct, and test a single-phase 120-V, 3.3-kW downscaled model with N=3, in order to verify the feasibility and effectiveness. The downscaled model helps to develop an operable 6.6-kV system with focus on control and performance.

  17. Vehicle Driving Comfort Analysis for a Cable-stayed Bridge Considering Vehicle Bridge Coupled Vibration

    Microsoft Academic Search

    Li Yan; Bi Hong-tao

    2010-01-01

    The vibration problem induced by vehicle moving over cable-stayed bridge has been widely investigated, but most of previous work focused on dynamic response and security of bridge. In the view of comfort properties, the effects of bridge vibration on vehicle driving comfort are discussed in present paper. Taking the Nanjing 2nd bridge in China for example, applying self-compiling vehicle-bridge coupling

  18. Design of a soft-switched three-port converter with DSP control for power flow management in hybrid fuel cell systems

    Microsoft Academic Search

    H. Tao; A. Kotsopoulos; J. L. Duarte; M. A. M. Hendrix

    2005-01-01

    A zero-voltage-switched three-port bidirectional converter which is able to handle wide input voltage ranges such as fuel cells and supercapacitors is presented in this paper. The converter consists of three active bridges coupled by a three-winding transformer. A simplified duty cycle control method is introduced to extend the soft-switching range. The system is modeled and a dual-PI-loop control strategy is

  19. A zero-voltage and zero-current switching three-level DC-DC converter with secondary-assisted regenerative passive snubber

    Microsoft Academic Search

    Tingting Song; Nianci Huang; Adrian Ioinovici

    2004-01-01

    An energy-recovery snubber, developed previously for full-bridge PWM phase-shift converters, is inserted in the secondary side of the transformer of a three-level converter. As a result, ZVS is obtained for the outer power switches and ZCS for the inner switches. The voltage on the rectifier diodes is clamped at a reasonable voltage, parasitic secondary ringing being avoided. The energy of

  20. Operational results of the Spallation Neutron Source (SNS) polyphase converter-modulator for the 140 kV klystron RF system

    Microsoft Academic Search

    W. A. Reass; James D. Doss; R. F. Gribble; M. T. Lynch; D. E. Rees; P. J. Tallerico; D. L. Borovina

    2001-01-01

    This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DC converter derives the bus voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three

  1. Design and implementation of high power DC-DC converter and speed control of DC motor using TMS320F240 DSP

    Microsoft Academic Search

    V. Kumar Chinnaiyan; J. Jerome; J. Karpagam; S. Shiek Mohammed

    2006-01-01

    This paper describes the design and implementation of high power DC-DC step- up converter using analog control circuits and speed control of DC motor using TMS320F240 DSP. In this technique a 24 V DC input supply is converted into 135 V DC by two-stage conversion. The full bridge topology is proposed for step up the DC voltage. The output of

  2. Thermionic converter studies at Thermo Electron

    Microsoft Academic Search

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

    1977-01-01

    The Thermionic Energy Converter (TEC) development program includes theoretical and experimental surface studies, diode evaluation, enhanced mode converter investigations and system studies, as well as materials fabrication and testing. The primary effort has been concentrated on increasing converter performance via improved electrodes. Diodes with oxide collectors (i.e., tungsten oxide, titanium oxide, zinc oxide and barium oxide) have provided the best

  3. Agilent 11982A Amplified Lightwave Converter

    E-print Network

    Park, Namkyoo

    Agilent 11982A Amplified Lightwave Converter Product Overview Wide bandwidth, sensitive O/E converter for characterizing lightwave systems and components Agilent's lightwave converter, the Agilent-end for lightwave frequency- and time- domain measurements. It can be used with Agilent spectrum analyzers

  4. Light-off behavior of catalytic converters

    Microsoft Academic Search

    P. S. Hagan; D. W. Schwendeman

    1994-01-01

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

  5. COMMUNITY ALERT INCIDENT: Catalytic Converter Thefts

    E-print Network

    Rose, Michael R.

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

  6. Right Coronary Artery Distribution of Myocardial Bridging

    PubMed Central

    Nguyen, Trung H.; Burnside, Patrick R.; Dieter, Robert S.; Nanjundappa, Aravinda

    2007-01-01

    Myocardial bridging has been observed to provoke symptoms in association with strenuous physical activity and hypertrophic cardiomyopathy; more recently, bridging has been thought to cause coronary vasospasm. Autopsy findings tend to reveal higher incidences of bridging than do angiography series, but both show an almost uniform predilection for left coronary artery distribution—especially in regard to bridging that manifests itself clinically. Herein, we report an unusual case of myocardial bridging with right coronary artery distribution and important clinical implications for physicians' management of similar cases in the future. PMID:18172538

  7. Lightweight multiple output converter development

    NASA Technical Reports Server (NTRS)

    Kisch, J. J.; Martinelli, R. M.

    1978-01-01

    A high frequency, multiple output power conditioner was developed and breadboarded using an eight-stage capacitor diode voltage multiplier to provide +1200 Vdc, and a three-stage for -350 Vdc. In addition, two rectifier bridges were capacitively coupled to the eight-stage multiplier to obtain 0.5 and 0.65 a dc constant current outputs referenced to +1200 Vdc. Total power was 120 watts, with an overall efficiency of 85 percent at the 80 kHz operating frequency. All outputs were regulated to three percent or better, with complete short circuit protection. The power conditioner component weight and efficiency were compared to the equivalent four outputs of the 10 kHz conditioner for the 8 cm ion engine. Weight reduction for the four outputs was 557 grams; extrapolated in the same ratio to all nine outputs, it would be 1100 to 1400 grams.

  8. Auxiliary resonant DC tank converter

    DOEpatents

    Peng, Fang Z. (Knoxville, TN)

    2000-01-01

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

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

    E-print Network

    Tolbert, Leon M.

    to the dc bus. Many battery cells connected in series are required to support a high dc bus voltage, which is about twice the peak line voltage. This re- quirement of a high voltage storage battery leads an isolation transformer, and sinu- soidal input currents if a power factor correction (PFC) con- verter

  10. Epidithiodiketopiperazine biosynthesis: a four-enzyme cascade converts glutathione conjugates into transannular disulfide bridges.

    PubMed

    Scharf, Daniel H; Chankhamjon, Pranatchareeya; Scherlach, Kirstin; Heinekamp, Thorsten; Willing, Karsten; Brakhage, Axel A; Hertweck, Christian

    2013-10-11

    Enzyme quartet: Isolation of the first sulfur-bearing intermediate of the gliotoxin pathway in Aspergillus fumigatus and successful in?vitro conversion of the bisglutathione adduct into an intact epidithiodiketopiperazine by a four-enzyme cascade (including glutamyltransferase GliK and dipeptidase GliJ) revealed an outstanding adaptation of a primary metabolic pathway into natural product biosynthesis that is widespread in fungi. PMID:24039048

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

    E-print Network

    Tolbert, Leon M.

    proposes a hybrid energy system to integrate the variable-speed wind turbine, fuel cell, and battery using-speed wind turbine, fuel cell, and battery as an energy storage element. As shown in Fig. 2, the speed. The ac output of the fuel cell energy source and the ac output of wind turbine - generator system can

  12. Strengthening Bridges with Prestressed CFRP Strips

    NASA Astrophysics Data System (ADS)

    Siwowski, Tomasz; ?ó?towski, Piotr

    2012-06-01

    Limitation of bridge's carrying bearing capacity due to aging and deterioration is a common problem faced by road administration and drivers. Rehabilitation of bridges including strengthening may be applied in order to maintain or upgrade existing bridge parameters. The case studies of strengthening of two small bridges with high modulus prestressed CFRP strips have been presented in the paper. The first one - reinforced concrete slab bridge - and the other - composite steel-concrete girder bridge - have been successfully upgraded with quite new technology. In both cases the additional CFRP reinforcement let increasing of bridge carrying capacity from 15 till 40 metric tons. The CFRP strip prestressing system named Neoxe Prestressing System (NPS), developed by multi-disciplinary team and tested at full scale in Rzeszow University of Technology, has been also described in the paper.

  13. Sustainability in bridge construction processes

    Microsoft Academic Search

    Pedro Pacheco; António P. Adão da Fonseca; André Resende; Rui Campos

    2010-01-01

    Sustainability must be seen as a global issue. In order to achieve that goal, it is necessary to apply its principles to all\\u000a industrial activities, including those that are not traditionally engaged with such guidelines, which is the case of Bridge\\u000a Construction. This paper evaluates the consumption of steel and energy and the emissions of carbon dioxide due to the

  14. Modeling and space vector control of a novel multilevel matrix converter for variable-speed wind power generators

    NASA Astrophysics Data System (ADS)

    Al-Naseem, Osama Abdulrahman

    A novel multilevel matrix converter is developed to efficiently transfer energy between a three-phase variable-speed generator of a wind turbine and a three-phase ac utility network. Optimizing the energy transfer efficiency at light load is critical in variable-speed wind generators. Laboratory experiment suggests that converter efficiency at light load may be increased via soft-switching and multilevel switching techniques. The new converter includes the advantages of multilevel converters, such as reduced harmonic content, increased power handling capability without additional switching loss, and high efficiency at low machine voltages. It also features the characteristics of conventional matrix converters, such as space vector control and improved efficiency via auxiliary resonant commutation soft-switching techniques. Similar to a conventional matrix converter, the novel multilevel matrix converter uses a nine-switch matrix with four-quadrant switches to connect input phases at one side of the converter with output phases at the other side of the converter. However, the switches of the new converter are configured differently from those used in the conventional matrix converter. Each switch of the new converter is a cell that resembles a full-bridge inverter topology and can assume three voltage levels while used. Semiconductor devices in a switch cell are always clamped to a known constant do voltage of a capacitor. This is a typical characteristic of multilevel converters where device voltage stresses are reduced by clamping the main transistor voltages to low levels. With reduced voltage stresses, switching frequency can be increased to allow for reduced size of filter magnetics. Unlike conventional matrix converter, the multilevel matrix converter uses inductors on both input and output sides of the converter. This symmetry allows for both step up and step down operations. Each switch cell features double the power handling capability compared to the four-quadrant switches used in a conventional matrix converter. This increase in power handling capability is due to the doubling of the number of devices in a multilevel matrix converter switch cell. Scaling up the power handling capability is accomplished by cascading more than one switch cell per branch. Control of the new converter is achieved through space vector modulation in which three-phase ac voltages are transformed to the d-q reference frame and compared with a set of space vectors prior to modulation. Since it has 19683 different switching combinations, control can be difficult and complex. Nevertheless, the multilevel matrix converter has been modeled and controlled through simulation. Simulation results show the possibility of operating the converter to produce the desired voltage waveforms with universal input and output power factors and maintain constant capacitor voltages simultaneously. Also in this dissertation is the derivation of an analytical averaged equivalent circuit model of a PWM converter. This model reveals how dominant loss mechanisms vary with converter operating point. The model is based on the operational characteristics of power diodes and IGBTs. Laboratory experiments support the derived model and confirm that IGBT current tailing and diode reverse-recovery are indeed the most critical losses in a PWM converter. These losses are more significant at light load, hence reducing the energy capture capability of converters used in wind generation. The results suggest that multilevel conversion, which has been employed in the novel multilevel matrix converter, could improve the low-wind converter efficiency.

  15. High power density dc-to-dc converters for aerospace applications

    NASA Astrophysics Data System (ADS)

    Divan, Deepakraj M.

    1990-12-01

    Three dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. Of the three circuits, the single-phase and three-phase versions of the dual active bridge topology demonstrate minimal stresses, better utilization of the transformer, bidirectional, and buck-boost modes of operation. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. The power transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. Based on the single-phase dual active bridge topology, a 50 kW, 50 kHz converter operating at an input voltage of 200 Vdc and an output voltage of 1600 Vdc was fabricated. Characteristics of current-fed output make the dual active bridge topologies amenable to paralleling and hence extension to megawatt power levels. Projections to a 1 MW system operating from a 500 Vdc input, at an output voltage of 10 kVdc and a switching frequency of 50 kHz, using MOS-controlled thyristors, coaxially wound transformers operating at three times the present current density with cooling, and multilayer ceramic capacitors, suggests an overall power density of 0.075 to 0.08 kg/kW and an overall efficiency of 96 percent.

  16. High power density dc-to-dc converters for aerospace applications

    NASA Technical Reports Server (NTRS)

    Divan, Deepakraj M.

    1990-01-01

    Three dc-to-dc converter topologies aimed at high-power high-frequency applications are introduced. Major system parasitics, namely, the leakage inductance of the transformer and the device output capacitance are efficiently utilized. Of the three circuits, the single-phase and three-phase versions of the dual active bridge topology demonstrate minimal stresses, better utilization of the transformer, bidirectional, and buck-boost modes of operation. All circuits operate at a constant switching frequency, thus simplifying design of the reactive elements. The power transfer characteristics and soft-switching regions on the Vout-Iout plane are identified. Two coaxial transformers with different cross-sections were built for a rating of 50 kVA. Based on the single-phase dual active bridge topology, a 50 kW, 50 kHz converter operating at an input voltage of 200 Vdc and an output voltage of 1600 Vdc was fabricated. Characteristics of current-fed output make the dual active bridge topologies amenable to paralleling and hence extension to megawatt power levels. Projections to a 1 MW system operating from a 500 Vdc input, at an output voltage of 10 kVdc and a switching frequency of 50 kHz, using MOS-controlled thyristors, coaxially wound transformers operating at three times the present current density with cooling, and multilayer ceramic capacitors, suggests an overall power density of 0.075 to 0.08 kg/kW and an overall efficiency of 96 percent.

  17. Catalytic converter for an automobile

    SciTech Connect

    Retallick, W.B.

    1986-03-18

    A catalytic converter is described for an automobile comprising a single strip of metal folded back and forth upon itself, the strip having at least one slot along each line of folding, the slots being aligned with each other across adjacent layers of the strip, each folded slot defining a notch. The notches together define at least one groove along the periphery of the folded strip, and at least one canister section, the canister section being shaped to coincide with the shape of the folded strip, the canister section having at least one ridge shaped to mate with the groove, the canister section being wrapped around the folded strip so as to maintain the strip in a fixed position.

  18. Thermionic converter studies at Thermo Electron

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  19. Performance of Power Converters at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DC converters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DC converters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.

  20. Radiation-Tolerant DC-DC Converters

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  1. Dynamics and Statics of Nonaxisymmetric Liquid Bridges

    NASA Technical Reports Server (NTRS)

    Alexander, J. Iwan D.; Resnick, Andrew H.; Slobozhanin, L. A.

    1996-01-01

    Theoretical and experimental investigation of the stability of nonaxisymmetric and nonaxisymmetric bridges contained between equal and unequal radii disks as a function of Bond and Weber number with emphasis on the transition from unstable axisymmetric to stable nonaxisymmetric shapes, are conducted. Numerical analysis of the stability of nonaxisymmetric bridges between unequal disks for various orientations of the gravity vector is performed. Experimental and theoretical investigation of large (nonaxisymmetric) oscillations and breaking of liquid bridges are also conducted.

  2. Measurement of Deflection Line on Bridges

    NASA Astrophysics Data System (ADS)

    Urban, Rudolf; Štroner, Martin

    2013-12-01

    Prestressed concrete bridges are very sensitive to the increase in long-term deflections. Reliable forecasts of deflections of bridge structures during construction and durability are crucial for achieving good durability. The main results of measurements are the changes of the deflection line of the bridge structures, which places special demands on the measurement procedure. Results from measurements are very useful for the improvement of mathematical prediction methods of behaviour of long span prestressed concrete structures.

  3. Harvesting traffic-induced bridge vibrations

    Microsoft Academic Search

    T. Galchev; J. McCullagh; R. L. Peterson; K. Najafi

    2011-01-01

    This paper demonstrates the harvesting of low-frequency and low-amplitude vibration energy from a suspension bridge. The performance of a Parametric Frequency Increased Generator (PFIG) (1) is evaluated at different locations along the bridge. Bridge vibrations have very low acceleration 0.1-1 m\\/s 2 and variable frequency characteristics (1-40 Hz), making them very challenging to harvest. Field test results show consistent operation

  4. A Novel Lossless Snubber for Boost Converters

    Microsoft Academic Search

    J. Marshall; M. Kazerani

    2006-01-01

    Advanced transportation technologies, such as hybrid-electric vehicles, battery-electric vehicles, and fuel cell vehicles, rely on high-power DC\\/DC converters to interconnect and manage their power systems. Boost converters are especially useful in stepping-up the voltage from a battery or fuel cell to match the electric motor voltage range. However, conventional high-power boost converters are very large and heavy, partly due to

  5. DC/DC Converter Stability Testing Study

    NASA Technical Reports Server (NTRS)

    Wang, Bright L.

    2008-01-01

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

  6. Development of Hybrid Bridges: State of Arts and Conceptual Design

    Microsoft Academic Search

    Suhaib Yahya Kasim Al-Darzi; Airong Chen

    2006-01-01

    A state of the art of developments of the Hybrid bridges is presented focusing on steel-concrete composite bridges, considering the steel beam, concrete deck and connections developments. The analysis and design methods of composite bridge structures, connections, the reliability and life cycle of bridges, new bridge system forms and the use of alternative materials are reviewed with some possible applications.

  7. Piezoelectric energy harvesting from traffic-induced bridge vibrations

    E-print Network

    Paris-Sud XI, Université de

    Piezoelectric energy harvesting from traffic-induced bridge vibrations Micha¨el Peigney1 harvesting of traffic-induced vibrations in bridges. Using a pre-stressed concrete highway bridge as a case-induced bridge vibrations 2 1. Introduction This paper focuses on using bridge vibrations as an energy source

  8. 1 INTRODUCTION Full-scale dynamic testing of operational bridges

    E-print Network

    Lynch, Jerome P.

    to monitor the vibration response of the 180 meter long Yeondae Bridge, Korea. The bridge consists of a steel1 INTRODUCTION Full-scale dynamic testing of operational bridges can be carried out for a multitude of a bridge. Fur- thermore, the overall state or condition of a bridge can be determined using response data

  9. 1 MHz, 1 kW series resonant converter for ultrasonic transducer using the high frequency power SITs

    Microsoft Academic Search

    Masataka TATSUTA; E. Yamanaka; H. Wada; T. Tamamushi; J.-I. Nishizawa

    1988-01-01

    A 1000 V, 30 A high-breakdown-voltage power static induction transistor (SIT) has been developed. It has a unity gain frequency of 50 MHz and a drain power dissipation of 500 W. Using these power SITs with a half bridge circuit, a 1 MHz, 1 kW series resonance converter for driving an ultrasonic transducer has been realized that has an efficiency

  10. 6. VIEW OF GDOT BRIDGE NO. 02700268X00678N BRIDGE PLATE IDENTIFYING ...

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

    6. VIEW OF GDOT BRIDGE NO. 027-00268X-00678N BRIDGE PLATE IDENTIFYING COUNTY COMMISSIONERS AT THE TIME OF CONSTRUCTION. - GDOT Bridge No. 027-00268X-00678N, County Road 268-Empress Road span Piscola Creek, Quitman, Brooks County, GA

  11. FBG bending gauge on bridges: an effort towards standardization of bridge structural health monitoring

    Microsoft Academic Search

    I.-Wen Wu; Chung-Yue Wang; Ming-Hung Chen; Hao-Lin Wang; Allen Cheng; Patrick Tsai; David Wu; Hung-Wei ChangChien; Hentai Shang

    2007-01-01

    The FBG bending gauge developed by POFC is applied in several situations involving bridge safety\\/health monitoring. Under static loading conditions, the FBG bending gauge serves as an excellent tool to deduce an overall deflection curve on the bridge section under study. The gauge also works well in dynamic situations where instantaneous vertical deflections of bridge structures resulting from a cruising

  12. A closely regulated TWT converter.

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

    The design concept for the TWT amplifier converter for possible use in the Thermoelectric Outer Planet Spacecraft (TOPS) is presented. An unusual combination of semiconductors and magnetics was utilized to achieve very stable voltage regulation on a number of separate outputs to satisfy the requirements of a high-power TWT, and at the same time operate at an efficiency of better than 90% from a 30-V source. The circuitry consists of an output filter, an auxiliary Jensen oscillator driving a high-reactance transformer to provide current limiting to the heater, a variable time delay, a main Jensen oscillator driving the power transformer with a maximum step-up ratio of 120 to 1, and series transistorized post regulators to provide precise voltage adjustment and low output impedance. This paper discusses the design of the high-reactance transformer and the high step-up ratio transformer, as well as the high-voltage series regulators that are limited in range and operate at the top of the unregulated output voltage. Test data are presented, and details of current transients caused by charging the filter circuits, input current ripple, and output voltage ripples are considered.

  13. Vacuum-insulated catalytic converter

    DOEpatents

    Benson, David K. (Golden, CO)

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  14. Salt-bridge energetics in halophilic proteins.

    PubMed

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

    2014-01-01

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

  15. Salt-Bridge Energetics in Halophilic Proteins

    PubMed Central

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

    2014-01-01

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

  16. The Bridge of Mandolin County

    NASA Astrophysics Data System (ADS)

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

    1999-12-01

    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 made on behalf of sodium chloride, the traditional deicer, and calcium magnesium acetate, a new environmentally friendly deicer, to arrive at the most cost-effective and environmentally appropriate deicing product. As they work through the analysis they raise questions that can be addressed in a laboratory setting. Four optional role-playing experiments are included, which can be used by the students to gather information helpful to resolution of the case. The case is intended to be used over two class periods, with a laboratory period in between, though suggestions for other models are provided. Laboratory procedures include an EDTA titration for Ca2+ and Mg2+, a gravimetric analysis, a qualitative examination of ions and solubility, an introduction to freezing point depression and measurement, and an experimental design activity. This case can also successfully be used without alteration in non-majors chemistry or environmental chemistry courses, or upper-level analytical or environmental chemistry courses.

  17. Digital control for phase shift converter

    Microsoft Academic Search

    R. Etz; T. Patarau; D. Petreus; S. Daraban; D. Moga

    2012-01-01

    The development of intelligent microgrids with renewable energy sources increased significantly nowadays. The present paper examines and compares analog and digital control of a bidirectional phase shift converter in order to find out which is best suited to be used in intelligent microgrid applications. New small signal models for the direct and reverse power flow transfer modes of the converter

  18. Control strategy for a Teniente Converter

    Microsoft Academic Search

    L. G. Bergh; P. Chacana; C. Carrasco

    2005-01-01

    A diagnosis of the actual distributed control and measurements system for a Teniente Converter, processing copper concentrates, is presented. Besides the importance of this converter in Caletones Smelter, there is a number of unsolved problems related to lack of instrumentation, lack of process knowledge, odd operating practices, and lack of procedures to process data to aid management and operating decisions.

  19. Distributed electrical leads for thermionic converter

    DOEpatents

    Fitzpatrick, Gary O. (Livermore, CA); Britt, Edward J. (Cupertino, CA)

    1979-01-01

    In a thermionic converter, means are provided for coupling an electrical lead to at least one of the electrodes thereof. The means include a bus bar and a plurality of distributed leads coupled to the bus bar each of which penetrates through one electrode and are then coupled to the other electrode of the converter in spaced apart relation.

  20. Power Converters Secure Electronics in Harsh Environments

    NASA Technical Reports Server (NTRS)

    2013-01-01

    In order to harden power converters for the rigors of space, NASA awarded multiple SBIR contracts to Blacksburg, Virginia-based VPT Inc. The resulting hybrid DC-DC converters have proven valuable in aerospace applications, and as a result the company has generated millions in revenue from the product line and created four high-tech jobs to handle production.