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

A novel four-branches-inverter-based-active-filter for harmonic suppression and reactive compensation of an unbalanced three-phase four-wires electrical distribution systems, feeding AC\\/DC loads  

Microsoft Academic Search

This paper deals with the design, analysis and digital simulation of a novel four-branches-inverter-based-active-filter, that compensates the reactive power and suppress the harmonic currents in the phases and neutral of an unbalanced three-phase four-wires electrical distribution system, feeding AC\\/DC loads. That is, the filter has the capability to instantaneously suppress the harmonics currents, in both the three-phases and the neutral,

Alfredo Nava-Segura; G. Mino-Aguilar

2000-01-01

2

LANSCE-R WIRE-SCANNER SYSTEM  

SciTech Connect

The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wirescanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sensewire interface with variable DC wire bias and wireintegrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.

Gruchalla, Michael E. [Los Alamos National Laboratory

2011-01-01

3

A Prototype Wire Position Monitoring System  

SciTech Connect

The Wire Position Monitoring System (WPM) will track changes in the transverse position of LCLS Beam Position Monitors (BPMs) to 1{micro}m over several weeks. This position information will be used between applications of beam based alignment to correct for changes in component alignment. The WPM system has several requirements. The sensor range must be large enough so that precision sensor positioning is not required. The resolution needs to be small enough so that the signal can be used to monitor motion to 1{micro}m. The system must be stable enough so that system drift does not mimic motion of the component being monitored. The WPM sensor assembly consists of two parts, the magnetic sensor and an integrated lock-in amplifier. The magnetic sensor picks up a signal from the alternating current in a stretched wire. The voltage v induced in the sensor is proportional to the wire displacement from the center of the sensor. The integrated lock-in amplifier provides a DC output whose magnitude is proportional to the AC signal from the magnetic sensor. The DC output is either read on a digital voltmeter or digitized locally and communicated over a computer interface.

Wang, Wei

2010-12-07

4

Experimental results of a three-level four-wire unidirectional AC-DC-AC converter  

Microsoft Academic Search

This paper presents a unidirectional neutral-point-clamped three-level four-wire AC-DC-AC converter topology and studies how space vector modulation and vector control can be applied to the converter. It is shown that either the rectifier or inverter can utilize discontinuous modulation if the injected zero-sequence voltage is properly chosen and a method for balancing the partial DC-link voltages is presented. The analysis

J. Alahuhtala; H. Tuusa

2010-01-01

5

An investigation on effects of wire-EDM machining parameters on surface roughness of newly developed DC53 die steel  

Microsoft Academic Search

DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper investigated the effects of machining parameters on surface roughness of wire EDMed DC53 die steel. The investigated

K. Kanlayasiri; S. Boonmung

2007-01-01

6

SpaceWire Data Handling Demonstration System  

NASA Astrophysics Data System (ADS)

The SpaceWire standard was published in 2003 with the aim of providing a standard for onboard communications, defining the physical and data link layers of an interconnection, in order to improve reusability, reliability and to reduce the cost of mission development. The many benefits which it provides mean that it has already been used in a number of missions, both in Europe and throughout the world. Recent work by the SpaceWire community has included the development of higher level protocols for SpaceWire, such as the Remote Memory Access Protocol (RMAP) which can be used for many purposes, including the configuration of SpaceWire devices. Although SpaceWire has become very popular, the various ways in which it can be used are still being discovered, as are the most efficient ways to use it. At the same time, some in the space industry are not even aware of SpaceWire's existence. This paper describes the SpaceWire Data Handling Demonstration System that has been developed by the University of Dundee. This system simulates an onboard data handling network based on SpaceWire. It uses RMAP for all communication, and so demonstrates how SpaceWire and standardised higher level protocols can be used onboard a spacecraft. The system is not only a good advert for those who are unfamiliar with the benefits of SpaceWire, it is also a useful tool for those using SpaceWire to test ideas.

Mills, S.; Parkes, S. M.; O'Gribin, N.

2007-08-01

7

dc Josephson current in a long multichannel quantum wire  

NASA Astrophysics Data System (ADS)

The dc Josephson current across a multichannel superconductor-normal-superconductor (SNS) junction is computed by summing contributions from subgap Andreev bound states, as well as from continuum states propagating within the superconducting leads. We show that, in a long multichannel SNS junction, at low temperatures, all these contributions add up, so that the current can be entirely expressed in terms of single-particle normal and Andreev reflection amplitudes at the Fermi level at both SN interfaces. Our derivation applies to a generic number of channels in the normal region and/or in the superconducting leads, without assumptions about scattering processes at the SN interfaces: if the channels within the central region have the same dispersion relation, it leads to simple analytical formulas for the current at low temperatures; if the channels within the central region have different dispersion relations, it allows for expressing the current in terms of a simple integral involving only scattering amplitudes at the Fermi level. Our result motivates using a low-energy effective boundary Hamiltonian formalism for computing the current, which is crucial for treating Luttinger liquid interaction effects.

Giuliano, Domenico; Affleck, Ian

2014-07-01

8

A Vibrating Wire System For Quadrupole Fiducialization  

SciTech Connect

A vibrating wire system is being developed to fiducialize the quadrupoles between undulator segments in the LCLS. This note provides a detailed analysis of the system. The LCLS will have quadrupoles between the undulator segments to keep the electron beam focused. If the quadrupoles are not centered on the beam axis, the beam will receive transverse kicks, causing it to deviate from the undulator axis. Beam based alignment will be used to move the quadrupoles onto a straight line, but an initial, conventional alignment must place the quadrupole centers on a straight line to 100 {micro}m. In the fiducialization step of the initial alignment, the position of the center of the quadrupole is measured relative to tooling balls on the outside of the quadrupole. The alignment crews then use the tooling balls to place the magnet in the tunnel. The required error on the location of the quadrupole center relative to the tooling balls must be less than 25 {micro}m. In this note, we analyze a system under construction for the quadrupole fiducialization. The system uses the vibrating wire technique to position a wire onto the quadrupole magnetic axis. The wire position is then related to tooling balls using wire position detectors. The tooling balls on the wire position detectors are finally related to tooling balls on the quadrupole to perform the fiducialization. The total 25 {micro}m fiducialization error must be divided between these three steps. The wire must be positioned onto the quadrupole magnetic axis to within 10 {micro}m, the wire position must be measured relative to tooling balls on the wire position detectors to within 15 {micro}m, and tooling balls on the wire position detectors must be related to tooling balls on the quadrupole to within 10 {micro}m. The techniques used in these three steps will be discussed. The note begins by discussing various quadrupole fiducialization techniques used in the past and discusses why the vibrating wire technique is our method of choice. We then give an overview of the measurement system showing how the vibrating wire is positioned onto the quadrupole axis, how the wire position detectors locate the wire relative to tooling balls without touching the wire, and how the tooling ball positions are all measured. The novel feature of this system is the vibrating wire which we discuss in depth. We analyze the wire dynamics and calculate the expected sensitivity of the system. The note should be an aid in debugging the system by providing calculations to compare measurements to.

Wolf, Zachary

2010-12-13

9

Spread spectrum modulation system for burst mode DC-DC converters  

E-print Network

This thesis develops a spread spectrum switching system for DC-DC converters operating in burst mode. Burst mode DC-DC converters have high efficiency under low-power conditions in applications such as cell phones and ...

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

2006-01-01

10

Integrated piezoelectric direct current sensor with actuating and sensing elements applicable to two-wire dc appliances  

NASA Astrophysics Data System (ADS)

A cantilever-based oscillating type MEMS dc current sensor integrated with actuating and sensing piezoelectric plates and a micromagnet was proposed for measuring electricity consumption in a single-wire or two-wire appliance cord. A prototype MEMS dc current sensor, with a resonant frequency of 32 Hz, was microfabricated and characterized. In the case of a two-wire electrical appliance cord, it was found that the relative change in the maximum value of the output voltage is approximately proportional to the applied dc current. The output voltage increased from 0 to 10 mV when the dc current was increased from 0 to 2 A under an excitation voltage of 6 Vpp. At the same time, the resonant frequency shift of the cantilever was observed to be monotonically increased over the applied dc current both theoretically and experimentally. In summary, the proposed MEMS dc current sensor was demonstrated to measure the output voltage constantly and nearly linearly over the applied dc current in a two-wire appliance without using a cord separator.

Wang, Dong F.; Suzuki, Yasuhiro; Suwa, Yosuke; Kobayashi, Takeshi; Itoh, Toshihiro; Maeda, Ryutaro

2013-12-01

11

Bidirectional DC to DC converters for fuel cell systems  

Microsoft Academic Search

This paper first describes the need of a bi-directional DC to DC converter for a fuel cell system. Various combinations of current-fed and voltage-fed converters are explored for the application of different voltage levels. With a preliminary study, putting current-fed on low-voltage side and voltage fed on high voltage side indicated higher efficiency than the other way around. Two low-side

K. Wang; C. Y. Lin; L. Zhu; D. Qu; F. C. Lee; J. S. Lai

1998-01-01

12

DC-DC converter design for battery-operated systems  

Microsoft Academic Search

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

B. Arbetter; R. Erickson; D. Maksimovic

1995-01-01

13

Application of genetic algorithm-based fuzzy logic control in wire transport system of wire-EDM machine  

Microsoft Academic Search

Wire tension as well as wire feed should be controlled tightly for the geometry and corner accuracy of wire-EDM. In this paper, a closed-loop wire tension control system for Micro-Wire-EDM is presented to guarantee a smooth wire transport and a constant tension value. In order to keep smooth wire transportation and avoid wire breakage during wire feeding, the reel roller

Mu-Tian Yan; Chi-Cheng Fang

2008-01-01

14

In-Situ Wire Damage Detection System  

NASA Technical Reports Server (NTRS)

An In-Situ Wire Damage Detection System (ISWDDS) has been developed that is capable of detecting damage to a wire insulation, or a wire conductor, or to both. The system will allow for realtime, continuous monitoring of wiring health/integrity and reduce the number of false negatives and false positives while being smaller, lighter in weight, and more robust than current systems. The technology allows for improved safety and significant reduction in maintenance hours for aircraft, space vehicles, satellites, and other critical high-performance wiring systems for industries such as energy production and mining. The integrated ISWDDS is comprised of two main components: (1) a wire with an innermost core conductor, an inner insulation film, a conductive layer or inherently conductive polymer (ICP) covering the inner insulation film, an outermost insulation jacket; and (2) smart connectors and electronics capable of producing and detecting electronic signals, and a central processing unit (CPU) for data collection and analysis. The wire is constructed by applying the inner insulation films to the conductor, followed by the outer insulation jacket. The conductive layer or ICP is on the outer surface of the inner insulation film. One or more wires are connected to the CPU using the smart connectors, and up to 64 wires can be monitored in real-time. The ISWDDS uses time domain reflectometry for damage detection. A fast-risetime pulse is injected into either the core conductor or conductive layer and referenced against the other conductor, producing transmission line behavior. If either conductor is damaged, then the signal is reflected. By knowing the speed of propagation of the pulse, and the time it takes to reflect, one can calculate the distance to and location of the damage.

Williams, Martha; Roberson, Luke; Tate, Lanetra; Smith, Trent; Gibson, Tracy; Medelius, Pedro; Jolley, Scott

2012-01-01

15

A novel bidirectional DC-DC converter with high power efficiency for isolation in high voltage DC power feeding systems  

Microsoft Academic Search

Recently, the high voltage DC feeding system has been researched and developed to save electrical energy and to make use of the green energy from the solar cell, wind turbine and so forth. This paper presents a novel high efficiency DC-DC converter for isolation in high voltage DC feeding systems. The prototype 4.0kW bidirectional DC-DC converter has been made and

Masayuki Suetomi; Daisuke Imamichi; Shinji Matsumoto; Daisuke Ueda; Jong-Ruey Yang; Yoichi Ishizuka; Wengzong Lin; Hirofumi Matsuo

2011-01-01

16

Printed wiring board system programmer's manual  

NASA Technical Reports Server (NTRS)

The printed wiring board system provides automated techniques for the design of printed circuit boards and hybrid circuit boards. The system consists of four programs: (1) the preprocessor program combines user supplied data and pre-defined library data to produce the detailed circuit description data; (2) the placement program assigns circuit components to specific areas of the board in a manner that optimizes the total interconnection length of the circuit; (3) the organizer program assigns pin interconnections to specific board levels and determines the optimal order in which the router program should attempt to layout the paths connecting the pins; and (4) the router program determines the wire paths which are to be used to connect each input pin pair on the circuit board. This document is intended to serve as a programmer's reference manual for the printed wiring board system. A detailed description of the internal logic and flow of the printed wiring board programs is included.

Brinkerhoff, C. D.

1973-01-01

17

Telephone wire is backbone of security system  

SciTech Connect

Video provides a variety of low-cost, high-quality solutions in today`s security environment. Cost-conscious managers of power generation stations, casinos, prison facilities, military bases and office buildings are considering using regular telephone wire (unshielded twisted pair-UTP) within their existing systems as the backbone of a video to the PC, personal and video-conferencing and training are other areas where phone wire in a building can save money and provide an alternative to coax or fiber for video. More and more, businesses and government agencies are meeting their needs efficiently by using telephone wires for more than just telephones.

Brede, K.; Rackson, L.T.

1995-09-01

18

Component Minimized AC–DC–AC Single-Phase to Three-Phase Four-Wire Converters  

Microsoft Academic Search

This paper proposes two sets of topologies for single-phase to three-phase four-wire ac-dc-ac power conversion. All proposed configurations are characterized by reduction in the number of switches. The first set includes five configurations using ten power switches, while the second one includes six configu- rations using eight power switches. Such configurations are con- ceived for supplying three-phase four-wire loads and

Euzeli Cipriano dos Santos; Cursino Brandão Jacobina; Gregory Arthur de Almeida Carlos; Isaac Soares de Freitas

2011-01-01

19

A Bidirectional DC–DC Converter for an Energy Storage System With Galvanic Isolation  

Microsoft Academic Search

This paper addresses a bidirectional dc-dc converter suitable for an energy storage system with an additional function of galvanic isolation. An energy storage device such as an electric double layer capacitor is directly connected to a dc side of the dc-dc converter without any chopper circuit. Nevertheless, the dc-dc converter can continue operating when the voltage across the energy storage

Shigenori Inoue; Hirofumi Akagi

2007-01-01

20

Wiring design based on Global Energy Requirement criteria: a first step towards optimization of DC distribution voltage  

E-print Network

Solaires, Institut National de l'Energie Solaire (CEA-INES) 50, avenue du Lac Léman, 73377 Le Bourget duWiring design based on Global Energy Requirement criteria: a first step towards optimization of DC distribution voltage International Conference on Renewable Energy and Eco-Design in Electrical Engineering

Paris-Sud XI, Université de

21

Modeling of DC spacecraft power systems  

NASA Technical Reports Server (NTRS)

Future spacecraft power systems must be capable of supplying power to various loads. This delivery of power may necessitate the use of high-voltage, high-power dc distribution systems to transmit power from the source to the loads. Using state-of-the-art power conditioning electronics such as dc-dc converters, complex series and parallel configurations may be required at the interface between the source and the distribution system and between the loads and the distribution system. This research will use state-variables to model and simulate a dc spacecraft power system. Each component of the dc power system will be treated as a multiport network, and a state model will be written with the port voltages as the inputs. The state model of a component will be solved independently from the other components using its state transition matrix. A state-space averaging method is developed first in general for any dc-dc switching converter, and then demonstrated in detail for the particular case of the boost power stage. General equations for both steady-state (dc) and dynamic effects (ac) are obtained, from which important transfer functions are derived and applied to a special case of the boost power stage.

Berry, F. C.

1995-01-01

22

Integrated Electrical Wire Insulation Repair System  

NASA Technical Reports Server (NTRS)

An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

2013-01-01

23

A review of wiring system safety in space power systems  

NASA Technical Reports Server (NTRS)

Wiring system failures have resulted from arc propagation in the wiring harnesses of current aerospace vehicles. These failures occur when the insulation becomes conductive upon the initiation of an arc. In some cases, the conductive path of the carbon arc track displays a high enough resistance such that the current is limited, and therefore may be difficult to detect using conventional circuit protection. Often, such wiring failures are not simply the result of insulation failure, but are due to a combination of wiring system factors. Inadequate circuit protection, unforgiving system designs, and careless maintenance procedures can contribute to a wiring system failure. This paper approaches the problem with respect to the overall wiring system, in order to determine what steps can be taken to improve the reliability, maintainability, and safety of space power systems. Power system technologies, system designs, and maintenance procedures which have led to past wiring system failures will be discussed. New technologies, design processes, and management techniques which may lead to improved wiring system safety will be introduced.

Stavnes, Mark W.; Hammoud, Ahmad N.

1993-01-01

24

System Identification of Wire Electrical Discharge Machining  

Microsoft Academic Search

In wire electrical discharge machining (wire-EDM), it is very important to restrain the vibration of the tool wire electrode for the improvement of machining accuracy. In this paper, investigation is carried out toward the dynamic wire vibration mechanism and a mathematical model is derived. This model is compared with experimental results. The measured displacement of a wire electrode in machining

N. Mohri; H. Yamada; K. Furutani; T. Narikiyo; T. Magara

1998-01-01

25

Headlamp modelling for simulating the capacity of automotive wiring systems  

Microsoft Academic Search

This paper presents a headlamp model that can be used as part of a computer simulation of a wiring system in a vehicle. As more electrical equipment is installed in a vehicle, the wiring system connecting such equipment becomes more complicated, and thus it is essential to conduct a simulation of the wiring system to coné rm its capacity. To

Hansang Lim; Jaehong Park

2003-01-01

26

ERCP wire systems: The long and the short of it  

PubMed Central

Guidewires are routinely used at the time of endoscopic retrograde cholangiopancreatography (ERCP) to gain and maintain access to the desired duct and aid in the advancement of various devices. Limitations of the traditional long-wire systems have led to the introduction of three proprietary short-wire systems. These systems differ in many respects but share two main principles: They lock a shorter wire in position to allow advancement or removal of various devices without displacement of the wire and they all allow for physician control of the wire. In this comprehensive review, we describe the key features of the three currently available short-wire systems: RX, Fusion and V systems. We also focus on the potential benefits and drawbacks that accompany the short-wire concept as a whole and each specific system in particular. Although the available data are limited, it appears that the use of the short-wire systems lead to reduced procedure, fluoroscopy and device exchange times, decreased sedation requirements, improved wire stability and increased endoscopist control of the wire. Furthermore, the physician-controlled wire-guided cannulation has the potential to decrease ampullary trauma and the rate of post-ERCP pancreatitis. The short guidewire systems appear to be an improvement over the traditional long-wire systems but further studies directly comparing the two approaches are needed. PMID:19115468

Reddy, Shilpa Chandrupatla; Draganov, Peter V

2009-01-01

27

Space vector modulated and vector controlled three-level four-wire unidirectional ac-dc-ac converter  

Microsoft Academic Search

This paper presents a unidirectional neutral-point-clamped three-level four-wire AC-DC-AC converter topology and studies how space vector modulation and vector control can be applied to the converter. The modulator is based on standard complex plane space vector modulation and the zero-sequence voltage space is treated as an offset. The zero-sequence offset is realized by proper weighting of redundant vectors of the

Jarno Alahuhtala; Heikki Tuusa

2008-01-01

28

The dream and reality of automated wiring systems  

SciTech Connect

This article examines the use of computer programs for automated substation/switchgear wiring in order to cut production costs associated with wiring diagrams and documentation. The topics of the article include automating the process, schematic capture editor, wiring diagram editor, design aids and documentation, display formats, and system benefits.

Manno, R.; Dugan, D.

1994-01-01

29

In-Situ Wire Damage Detection System  

NASA Technical Reports Server (NTRS)

An in-situ system for detecting damage in an electrically conductive wire. The system includes a substrate at least partially covered by a layer of electrically conductive material forming a continuous or non-continuous electrically conductive layer connected to an electrical signal generator adapted to delivering electrical signals to the electrically conductive layer. Data is received and processed to identify damage to the substrate or electrically conductive layer. The electrically conductive material may include metalized carbon fibers, a thin metal coating, a conductive polymer, carbon nanotubes, metal nanoparticles or a combination thereof.

Williams, Martha K. (Inventor); Roberson, Luke B. (Inventor); Tate, Lanetra C. (Inventor); Smith, Trent M. (Inventor); Gibson, Tracy L. (Inventor); Jolley, Scott T. (Inventor); Medelius, Pedro J. (Inventor)

2014-01-01

30

Effects of wire-EDM machining variables on surface roughness of newly developed DC 53 die steel: Design of experiments and regression model  

Microsoft Academic Search

DC53 is a newly developed cold die steel from Daido Steel, Japan. It is an improvement over the familiar cold die steel SKD11. Because DC53 is a new die steel, only little information is available in literature for its machining characteristics. This paper presents an investigation of the effects of machining variables on the surface roughness of wire-EDMed DC53 die

K. Kanlayasiri; S. Boonmung

2007-01-01

31

Integration Infrastructure in Wireless\\/Wired Heterogeneous Industrial Network System  

Microsoft Academic Search

\\u000a As various wired Field-bus systems are still pervasive in present industrial and factory environments, it is very unlikely\\u000a that wireless communications will be able to replace current wired Field-bus systems in many industrial environments completely.\\u000a The integration of wireless and wired segment (networks) was studied in this paper. Three integration patterns on application\\u000a layer, physical layer, data-link layer were discussed

Haikuan Wang; Weiyan Hou; Zhaohui Qin; Yang Song

2010-01-01

32

Design and manufacture of a D-shape coil-based toroid-type HTS DC reactor using 2nd generation HTS wire  

NASA Astrophysics Data System (ADS)

This paper describes the design specifications and performance of a real toroid-type high temperature superconducting (HTS) DC reactor. The HTS DC reactor was designed using 2G HTS wires. The HTS coils of the toroid-type DC reactor magnet were made in the form of a D-shape. The target inductance of the HTS DC reactor was 400 mH. The expected operating temperature was under 20 K. The electromagnetic performance of the toroid-type HTS DC reactor magnet was analyzed using the finite element method program. A conduction cooling method was adopted for reactor magnet cooling. Performances of the toroid-type HTS DC reactor were analyzed through experiments conducted under the steady-state and charge conditions. The fundamental design specifications and the data obtained from this research will be applied to the design of a commercial-type HTS DC reactor.

Kim, Kwangmin; Go, Byeong-Soo; Sung, Hae-Jin; Park, Hea-chul; Kim, Seokho; Lee, Sangjin; Jin, Yoon-Su; Oh, Yunsang; Park, Minwon; Yu, In-Keun

2014-09-01

33

Stray current characteristics of DC transit systems  

SciTech Connect

The re-emergence and rapid growth of use of DC-powered transit systems around the world has led to the adaptation of three distinct operational modes: grounded, ungrounded, and diode grounded. Each of these modes causes widely varying amounts of stray current in systems using the running rails for negative return current. The advantages of each operational mode and the possible stray current effects on transit and adjacent utility structures are discussed.

Moody, K.J. (Parsons Brinckerhoff Quade Douglas Inc., Atlanta, GA (United States). Transportation Technologies Div.)

1994-06-01

34

Superconductivity for Electric Systems Annual Peer Review Washington, DC July 23-25, 2003 OAK RIDGE NATIONAL LABORATORY  

E-print Network

Superconductivity for Electric Systems Annual Peer Review Washington, DC ­ July 23-25, 2003 OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY American Superconductor Corporation M. W. Rupich, D-in ORNL-AMSC CRADA: Development of 2G YBCO-RABiTS Wires #12;Superconductivity for Electric Systems Annual

35

A simple three-channel dc SQUID system using time domain multiplexing M. Mck and M. Korn  

E-print Network

A simple three-channel dc SQUID system using time domain multiplexing M. Mück and M. Korn Justus) Conventional multichannel superconducting quantum interference device (SQUID) systems require a SQUID read-out circuit for each channel, as well as many wires connecting each individual SQUID and feedback coil

Le Roy, Robert J.

36

Electric vehicle DC charger integrated within a photovoltaic power system  

Microsoft Academic Search

Mitigation of the variability in output power of renewable generators such as solar photovoltaic (PV) systems is a growing concern as these generators reach higher penetrations on electric grids. This paper presents a system where a bidirectional, highly efficient, DC-DC electric vehicle (EV) charger is placed between the high-voltage DC bus of a PV system and the EV battery. In

Joshua Traube; Fenglong Lu; Dragan Maksimovic

2012-01-01

37

Design of automotive X-by-Wire systems Cdric Wilwert  

E-print Network

Design of automotive X-by-Wire systems Cédric Wilwert PSA Peugeot - Citroën 92000 La Garenne Phone : +33 3 83 58 17 62 simonot@loria.fr CONTENTS Design of automotive X-by-Wire systems ................................................................................................................................ 9 3.2 Main time-triggered protocols for automotive industry

Paris-Sud XI, Université de

38

The biomechanics of wire fixation in the Ilizarov system.  

PubMed

The purpose of this study was to establish the optimal fixation of tensioned wires to the frame construct in the Ilizarov system. The usual torque to which the fixation bolts were tightened in clinical practice was established by serial testing of orthopaedic surgeons' work in our unit. The force required to produce wire slippage from the different types of wire fixation bolts, tightened to a predetermined torque, was measured using a testing rig. Analysis of the usual torque to which bolts were tightened in clinical practice, revealed values in the range of 5-10Nm. The load required to cause failure of the tensioned wire varied considerably depending on the bolt configuration used and the applied torque. In clinical practice, wires are tensioned using a dynamometer to a variety of loads, depending on the clinical situation, up to 1275N. In applying multiple wires across a single ring, as is normal practice, these loads may be increased still further. The total load transmitted by single wires in weightbearing may be up to 2000N. Utilising the results of our work has enabled us to choose, where practically possible, the optimal bolt configuration for wire fixation. In addition, this work has revealed that in order to withstand the loads seen in clinical practice, wire fixation bolts should be tightened to at least 10Nm. Post-operatively, we now tighten all our wire fixation bolts to 10Nm, using a calibrated torque wrench. PMID:12565025

Mullins, M M; Davidson, A W; Goodier, David; Barry, M

2003-02-01

39

System and method for evaluating a wire conductor  

DOEpatents

A method of evaluating an electrically conductive wire segment having an insulated intermediate portion and non-insulated ends includes passing the insulated portion of the wire segment through an electrically conductive brush. According to the method, an electrical potential is established on the brush by a power source. The method also includes determining a value of electrical current that is conducted through the wire segment by the brush when the potential is established on the brush. The method additionally includes comparing the value of electrical current conducted through the wire segment with a predetermined current value to thereby evaluate the wire segment. A system for evaluating an electrically conductive wire segment is also disclosed.

Panozzo, Edward; Parish, Harold

2013-10-22

40

The DC-DC conversion power system of the CMS Phase-1 pixel upgrade  

NASA Astrophysics Data System (ADS)

The pixel detector of the CMS experiment will be exchanged during the year-end technical stop in 2016/2017, as part of the experiment's Phase-1 upgrade. The new device will feature approximately twice the number of readout channels, and consequently the power consumption will be doubled. By moving to a DC-DC conversion powering scheme, it is possible to power the new pixel detector with the existing power supplies and cable plant. The power system of the Phase-1 pixel detector is described and the performance of the new components, including DC-DC converters, DC-DC converter motherboards and various power distribution boards, is detailed. The outcome of system tests in terms of electrical behaviour, thermal management and pixel module performance is discussed.

Feld, L.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Schmitz, St.; Wlochal, M.

2015-01-01

41

Impact of Power Density Maximization on Efficiency of DC–DC Converter Systems  

Microsoft Academic Search

The demand for decreasing costs and volume leads to a constantly increasing power density of industrial converter systems. In order to improve the power density, further different aspects, like thermal management and electromagnetic effects, must be considered in conjunction with the electrical design. Therefore, a comprehensive optimization procedure based on analytical models for minimizing volume of DC-DC converter systems has

Juergen Biela; Uwe Badstuebner; Johann W. Kolar

2009-01-01

42

New Solar Cell Power Supply System Using a Boost Type Bidirectinal DC-DC Converter  

Microsoft Academic Search

A new solar cell power supply system is presented, in which the boost type bidirectional dc-dc converter and the simple control circuit with a small monitor solar cell are employed to track the maximum power point of the solar array. It is confirmed by the experiment that the new system has sufficiently precise tracking operation performance and satisfactorily high power

Hirofumi Matsuo; Fujio Kurokawa

1984-01-01

43

KIM-1 interface adapter to 3-wire teletype systems  

NASA Technical Reports Server (NTRS)

The KIM-1 circuit designed for use with a full duplex isolated 4 terminal system is described. Operation of the circuit with a 3 wire system in conjunction with a single +5v supply interface is discussed.

Burhans, R. W.

1976-01-01

44

Power systems analysis for direct current (dc) distribution systems  

SciTech Connect

Many standards, guidelines, etc., currently exist which provide guidance for dc power systems analysis. These documents are scattered throughout the industry (i.e., IEEE, UL, NEMA, GE, etc.), and primarily treat the subject as though hand calculations are being performed. It is the intent of this paper to provide guidance for performing computer aided dc power systems analyzes. This paper will cover load flow/voltage drop and short circuit calculations.

Fleischer, K. [Public Service Electric and Gas, Hancock`s Bridge, NJ (United States). Salem Nuclear Generating Station] [Public Service Electric and Gas, Hancock`s Bridge, NJ (United States). Salem Nuclear Generating Station; Munnings, R.S. [VECTRA Technologies, Inc., Lincolnshire, IL (United States)] [VECTRA Technologies, Inc., Lincolnshire, IL (United States)

1996-09-01

45

Beam Position and Phase Monitor - Wire Mapping System  

SciTech Connect

The Los Alamos Neutron Science Center (LANSCE) deploys many cylindrical beam position and phase monitors (BPPM) throughout the linac to measure the beam central position, phase and bunched-beam current. Each monitor is calibrated and qualified prior to installation to insure it meets LANSCE requirements. The BPPM wire mapping system is used to map the BPPM electrode offset, sensitivity and higher order coefficients. This system uses a three-axis motion table to position the wire antenna structure within the cavity, simulating the beam excitation of a BPPM at a fundamental frequency of 201.25 MHz. RF signal strength is measured and recorded for the four electrodes as the antenna position is updated. An effort is underway to extend the systems service to the LANSCE facility by replacing obsolete electronic hardware and taking advantage of software enhancements. This paper describes the upgraded wire positioning system's new hardware and software capabilities including its revised antenna structure, motion control interface, RF measurement equipment and Labview software upgrades. The main purpose of the wire mapping system at LANSCE is to characterize the amplitude response versus beam central position of BPPMs before they are installed in the beam line. The wire mapping system is able to simulate a beam using a thin wire and measure the signal response as the wire position is varied within the BPPM aperture.

Watkins, Heath A [Los Alamos National Laboratory; Shurter, Robert B. [Los Alamos National Laboratory; Gilpatrick, John D. [Los Alamos National Laboratory; Kutac, Vincent G. [Los Alamos National Laboratory; Martinez, Derwin [Los Alamos National Laboratory

2012-04-10

46

DC2S : a dynamic car sharing system  

Microsoft Academic Search

This paper presents DC2S, a dynamic car sharing system. It aims to solve traffic congestion problem by reducing empty seats traveling. In DC2S, dynamic means pervasive and smart. DC2S involves two main components. One is the pervasive client (mainly smart phones) and the other is the smart server. Smart phones automatically log and share users' traveling information. The DC2S server

Jianhua Shao; Chris Greenhalgh

2010-01-01

47

Novel solar cell power supply system using the multiple-input DC-DC converter  

Microsoft Academic Search

Recently, clean electric power generation systems have attracted a great deal of social attention to exploit clean energy resources such as solar arrays, wind generators, fuel cells, etc. In this case, the multiple-input DC-DC power converter is useful to combine the several input power sources and to supply the regulated output voltage for the load. The novel solar cell power

Hirohmi Matsuo; Kimiyoshi Kobayashi; Yutaka Sekine; Matsuyoshi Asano; Lin Wenzhong

1998-01-01

48

Modelling AC\\/DC systems for the analysis of AC\\/DC interactions  

Microsoft Academic Search

It is well documented that any given harmonic (or any given oscillation) on the AC side of an HVDC power converter is converted into frequencies on the DC side with frequency shifts based on multiples and complements of the fundamental frequency of the AC power system. In a similar fashion, oscillations on the DC side are converted to new frequencies

R. S. Burton

1995-01-01

49

BAE Systems Radiation Hardened SpaceWire ASIC and Roadmap  

NASA Technical Reports Server (NTRS)

An Application Specific Integrated Circuit (ASIC) that implements the SpaceWire protocol has been developed in a radiation hardened 0.25 micron CMOS, technology. This effort began in March 2003 as a joint development between the NASA Goddard Space Flight Center (GSFC) and BAE Systems. The BAE Systems SpaceWire ASlC is comprised entirely of reusable core elements, many of which are already flight-proven. It incorporates a 4-port SpaceWire router with two local ports, dual PC1 bus interfaces, a microcontroller, 32KB of internal memory, -and a memory controller for additional external memory use. The SpaceWire ASlC is planned for use on both the Geostationary Operational Environmental Satellites (GOES)-R and the Lunar Reconnaissance Orbiter (LRO). Engineering parts have already been delivered to both programs. This paper discusses the SpaceWire protocol and those elements of it that have been built into the current SpaceWire reusable core. There are features within the core that go beyond the current standard that can be enabled or disabled by the user and these will be described. The adaptation of SpaceWire to BAE Systems' On Chip Bus (OCB) for compatibility with the other reusable cores will be discussed. Optional configurations within user systems will be shown. The physical imp!ementation of the design will be described and test results from the hardware will be discussed. Finally, the BAE Systems roadmap for SpaceWire developments will be discussed, including some products already in design as well as longer term plans.

Berger, Richard; Milliser, Myrna; Kapcio, Paul; Stanley, Dan; Moser, David; Koehler, Jennifer; Rakow, Glenn; Schnurr, Richard

2006-01-01

50

Modeling and Implementation for Embedded DC Motor Ethernet Control System  

E-print Network

Modeling and Implementation for Embedded DC Motor Ethernet Control System Lingbo Zhu, Guanzhong Dai of Embedded DC Motor Ethernet Control System is proposed with analysis on transmission time delay and data packet dropout. Based on this model, the ECS is described as a two-state asynchronous dynamical system

Paris-Sud XI, Université de

51

The batteries as a principal component in DC UPS systems  

Microsoft Academic Search

The authors discuss the duties of batteries in DC uninterruptible power supply (UPS) or telecommunications power systems. They show how the battery system affects the DC UPS system reliability and availability performance, discuss the impact of public power and engine alternators on battery sizing, and determine the essential parameters to be monitored. Also discussed are the issues of battery fault

Teuvo Suntio; Arto Glad

1990-01-01

52

A Laser-Wire System at the ATF Extraction Line  

SciTech Connect

A new laser-wire (LW) system has been installed at the ATF extraction line at KEK, Tsukuba. The system aims at a micron-scale laser spot size and employs a mode-locked laser system. The purpose-built interaction chamber, light delivery optics, and lens systems are described, and the first results are presented.

Boogert, S.T.; Blair, G.; Boorman, G.; Bosco, A.; Deacon, L.; Driouichi, C.; Karataev, P.; /Royal Holloway, U. of London; Kamps, T.; /BESSY, Berlin; Delerue, N.; Dixit, S.; Foster, B.; Gannaway, F.; Howell, D.F.; Qureshi, M.; Reichold, A.; Senanayake, R.; /Oxford U.; Aryshev, A.; Hayano, H.; Kubo, K.; Terunuma, N.; Urakawa, J.; /KEK, Tsukuba /Liverpool

2007-02-12

53

Automobile Brake-by-Wire Control System Design and Analysis  

Microsoft Academic Search

The automobile brake-by-wire (BBW) system, which is also called the electromechanical brake system, has become a promising vehicle braking control scheme that enables many new driver interfaces and enhanced performances without a mechanical or hydraulic backup. In this paper, we survey BBW control systems with focuses on fault tolerance design and vehicle braking control schemes. At first, the system architecture

Weidong Xiang; Paul C. Richardson; Chenming Zhao; Syed Mohammad

2008-01-01

54

DC voltage control in DC feeding systems with using SOFC  

Microsoft Academic Search

Recently, dispersed generators have been installed in distribution network to supply power to commercial facilities. Renewable energy generation contains output power fluctuations and distributed generator produces sluggish response for power demand. In order to overcome these problems, an ultracapacitor energy storage system are used for compensation instantaneous power imbalance. However, it needs large capacity of ultracapacitor energy system resulting for

Kenichi Tanaka

2009-01-01

55

A hybrid smart AC\\/DC power system  

Microsoft Academic Search

Recently, a smart grid has been attracted attention from the background of the introduction promotion of natural energy. At present, a smart grid based on AC grid has been proposed. However, no paper or article has been presented or published on a smart grid based on DC grid. This paper presents a AC\\/DC hybrid power system. The system has advantages

Kyohei Kurohane; Tomonobu Senjyu; Akie Uehara; Atsushi Yona; Toshihisa Funabashi; Chul-Hwan Kim

2010-01-01

56

System for energy storage and dc to ac conversion  

Microsoft Academic Search

A system is disclosed for storing electrical energy and for converting dc power to ac power. The system includes a very large flywheel which is mounted in an evacuated housing and is driven by a plurality of wheels powered by dc electric motors which receive current from an input power source. An independent plurality of wheels coupled to ac generators

Diggs

1976-01-01

57

Operational environments for electrical power wiring on NASA space systems  

NASA Technical Reports Server (NTRS)

Electrical wiring systems are used extensively on NASA space systems for power management and distribution, control and command, and data transmission. The reliability of these systems when exposed to the harsh environments of space is very critical to mission success and crew safety. Failures have been reported both on the ground and in flight due to arc tracking in the wiring harnesses, made possible by insulation degradation. This report was written as part of a NASA Office of Safety and Mission Assurance (Code Q) program to identify and characterize wiring systems in terms of their potential use in aerospace vehicles. The goal of the program is to provide the information and guidance needed to develop and qualify reliable, safe, lightweight wiring systems, which are resistant to arc tracking and suitable for use in space power applications. This report identifies the environments in which NASA spacecraft will operate, and determines the specific NASA testing requirements. A summary of related test programs is also given in this report. This data will be valuable to spacecraft designers in determining the best wiring constructions for the various NASA applications.

Stavnes, Mark W.; Hammoud, Ahmad N.; Bercaw, Robert W.

1994-01-01

58

Fuzzy control of AC-DC converters supplying high precision DC drive systems  

Microsoft Academic Search

The paper describes an application of fuzzy set theory in a DC speed control system supplied by an AC-DC converter. The fuzzy control is used to linearize the external characteristics of the converter in discontinuous-conduction mode occurring at light load and\\/or high speed. The nonlinear characteristics in discontinuous-conduction mode affect the control loop gain. The solution is to linearize the

Adriana Florescu; Vasile Alexandru; D. A. Stoichescu

2001-01-01

59

Novel Solar-Cell Power Supply System Using a Multiple-Input DC–DC Converter  

Microsoft Academic Search

Recently, the clean electric power generation systems have attracted a great deal of social attention to exploit the clean-energy resources such as solar arrays, wind generators, fuel cells, and so forth. In this case, a multiple-input dc–dc converter is useful to combine the several input power sources and to supply the regulated output voltage for the load from the power

Kimiyoshi Kobayashi; Hirofumi Matsuo; Yutaka Sekine

2006-01-01

60

Wired.  

ERIC Educational Resources Information Center

Discusses technology's impact on scoreboard design: the development of the light-emitting diode (LED) display. How the LED system works is explained, as are the advantages and disadvantages of LED compared with incandescent lamp boards. Final comments address deciding on materials for scoreboard casings. (GR)

Conklin, Aaron R.

1998-01-01

61

Damping phenomena in a wire rope vibration isolation system  

NASA Technical Reports Server (NTRS)

A study is presented of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators, with emphasis placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase plane trajectories, and frequency response curves are obtained. A semiempirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed, and the results are compared to experimental data. Several observations and conclusions are made about the dynamic phenomena in a typical wire rope vibration isolation system based on the experimental and semiempirical results.

Tinker, M. L.; Cutchins, M. A.

1992-01-01

62

Damping phenomena in a wire rope vibration isolation system  

NASA Technical Reports Server (NTRS)

A study of the dynamic characteristics of a wire rope vibration isolation system constructed with helical isolators is presented. Emphasis is placed on the analytical modeling of damping mechanisms in the system. An experimental investigation is described in which the static stiffness curve, hysteresis curves, phase trajectories, and frequency response curves were obtained. A semi-empirical model having nonlinear stiffness, nth-power velocity damping, and variable Coulomb friction damping is developed and results are compared to experimental data. Conclusions about dynamic phenomena in the wire rope system are made based on the experimental and semi-empirical results.

Tinker, Michael L.; Cutchins, Malcolm A.

1990-01-01

63

A Bi-Directional Isolated DC/DC Converter as a Core Circuit for 3.3-kV/6.6-kV Power Conversion Systems in the Next Generation  

NASA Astrophysics Data System (ADS)

This paper describes a bi-directional isolated dc/dc converter considered as a core circuit of 3.3-kV/6.6-kV high-power-density power conversion systems in the next generation. The dc/dc converter is intended to use power switching devices based on SiC and/or GaN, which will be available on the market in the near future. A 350-V, 10-kW and 20kHz dc/dc converter is designed, constructed and tested in this paper. It consists of two single-phase full-bridge converters with the latest trench-gate Si-IGBTs and a 20-kHz transformer with a nano-crystalline soft-magnetic material core and litz wires. The transformer plays an essential role in achieving galvanic isolation between the two full-bridge converters. The overall efficiency from the dc-input to dc-output terminals is accurately measured to be as high as 97%, excluding gate drive circuit and control circuit losses from the whole loss. Moreover, loss analysis is carried out to estimate effectiveness in using SiC-based power switching devices. The loss analysis clarifies that the use of SiC-based power devices may bring a significant reduction in conducting and switching losses to the dc/dc converter. As a result, the overall efficiency may reach 99% or higher.

Inoue, Shigenori; Akagi, Hirofumi

64

Investigation of factors affecting loosening of Ilizarov ring-wire external fixator systems at the bone-wire interface.  

PubMed

The potential for peri-implant bone yielding and subsequent loosening of Ilizarov ring-wire external fixation systems was investigated using non-linear finite element (FE) analyses. A strain-based plasticity model was employed to simulate bone yielding. FE models also incorporated contact behavior at the wire-bone interface, orthotropic elasticity, and periosteal-endosteal variation of bone properties. These simulations were used to determine the extent and location of yielding with change in age-related bone structure and properties for the bone-Ilizarov construct at the tibial midshaft. At critical wire-bone interfaces, the predicted volume of yielded bone with four wires (on either side of the fracture) was ?40% of that with two wires. Old-aged cases showed considerably greater bone yielding at the wire-bone interface than young cases (1.7-2.2 times greater volumes of yielded bone). The volume of yielded bone at all wire-bone interfaces decreased with an increase in wire pre-tension. The absence of continuous through-thickness yielding offers an explanation for the clinical observation that Ilizarov ring-wire fixation can provide stable fracture fixation even in bone with high porosity. PMID:22042453

Donaldson, Finn E; Pankaj, Pankaj; Simpson, A Hamish R W

2012-05-01

65

Approach to steer-by-wire system design  

Microsoft Academic Search

Steer-by-wire (SbW) systems are candidate to substitute the conventional (mechanical or hydraulic) steering systems in the new generation of vehicles. The task of a SbW system is twofold: turning the road wheels tracking the handwheel rotation and providing the driver with a feeling of the steering effort. In this paper, the issue of designing a SbW system is faced. An

Manuele Bertoluzzo; Giuseppe Buja; Roberto Menis; G. Sulligoi

2005-01-01

66

Microprocessor-based control for an ac-dc power conversion system with dc interrupter protection  

Microsoft Academic Search

The use of microprocessors in power converted controls is of interest, since they could potentially reduce system costs, increase system adaptability, and enhance system reliability where analog circuitry is conventionally used. This report discusses the techniques that were applied in designing a complete microprocessor-controlled ac\\/dc power conversion system, including thyristor-gating control and closed-loop regulation of system voltages. The project also

L. J. Kovalsky; R. P. Putkovich

1982-01-01

67

Hybrid drive system of an industrial truck using a three-phase DC-DC converter feeding ultra-capacitors  

Microsoft Academic Search

The diesel-electric drive system of an industrial truck is extended with an energy storage subsystem utilizing ultra-capacitors thus establishing a reliable technical solution with a great energy saving potential. A bidirectional three-phase DC-DC converter is proposed to charge the ultra-capacitors during the regenerative braking of the electric drive and to discharge them when peak power is demanded. The developed DC-DC

C. Rudolph

2009-01-01

68

DC and Pulsed Septa for the LNLS UVX Injection System  

Microsoft Academic Search

The design, construction and installation of a pulsed thin septum and a d.c. thick septum for the LNLS UVX injection system is presented. The injection system uses two septa and three kickers to inject the 120 MeV electron beam coming from the Linac into the storage ring. The present system uses two d.c. septa. A pulsed thin septum was constructed

Ruy H. A. Farias; M. J. Ferreira; R. T. Neuenschwander; F. S. Rafael

1997-01-01

69

Brushless DC motor drive for steer-by-wire and electric power steering applications  

Microsoft Academic Search

Due to the growing demand of cars, trucks, and sport utility vehicles (SUVs) in today's society, there becomes the need to create automobiles that are optimized in different aspects. In current cars, many mechanical systems are robbing the conventional internal combustion engine from valuable horsepower. For instance, the steering systems of the most later model vehicles could be observed to

F. Rodriguez; E. Uy; A. Emadi

2003-01-01

70

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

NASA Astrophysics Data System (ADS)

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.

Kitada, Ryohei; Akagi, Hirofumi

71

New DC–DC Converter for Energy Storage System Interfacing in Fuel Cell Hybrid Electric Vehicles  

Microsoft Academic Search

The use of energy storage devices such as batteries or supercapacitors is almost mandatory in fuel cell hybrid electric vehicles, in order to guarantee load leveling, assuring braking energy recovery and good performances in transient operations. To this end, converters with bidirectional power flows are needed to connect the accumulators to the dc-link of the motor drive system. In this

Mario Marchesoni; Camillo Vacca

2007-01-01

72

Novel Resonant DC Link Soft Switching Inverter for Brushless DC Motor Drive System  

Microsoft Academic Search

Brushless DC motor (BLDCM) has been widely used in drive systems and servo control because of its fast response, high power density and high efficiency and so on. It is usually driven by a hard-switching PWM inverter, which has low switching frequency, high switching loss, high electro magnetic interference (EMI) and acoustic noise, etc. To solve the drawbacks of the

He Hucheng; Liu Weiguo; Dou Manfeng; Ma Ruiqing

2007-01-01

73

Advanced DC–DC converter for power conditioning in hydrogen fuel cell systems  

Microsoft Academic Search

The fuel cell (FC) generators can produce electric energy directly from hydrogen and oxygen. The DC voltage generated by FC is generally low amplitude and it is not constant, depending on the operating conditions. Furthermore, FC systems have dynamic response that is slower than the transient responses typically requested by the load. For this reason, in many applications the FC

G. Kovacevic; A. Tenconi; R. Bojoi

2008-01-01

74

Channel Characterization and EMC Assessment of a PLC System for Spacecraft DC Differential Power Buses  

Microsoft Academic Search

This paper investigates the possibility of using the powerline communications (PLC) technology to transmit data along differential dc power buses employed in spacecraft. To this end, a point-to-point interconnection between the power control and distribution unit (PCDU) and a dc\\/dc converter is consid- ered. The power bus is composed of a twisted-wire pair (TWP) above ground, and capacitive coupling and

Flavia Grassi; Sergio A. Pignari; Johannes Wolf

2011-01-01

75

Commissioning a Vibrating Wire System for Quadrupole Fiducialization  

SciTech Connect

Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of the quadrupoles. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing such a system. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). A previous study investigated the error associated with each step by using a permanent quadrupole magnet on an optical mover system. The study reported an error of 11{micro}m for step 1 and a repeatability of 4{micro}m for step 2. However, the set up used a FARO arm to measure tooling balls and didn't allow to accurately check step 2 for errors; an uncertainty of 100{micro}m was reported. Therefore, even though the repeatability was good, there was no way to check that the error in step 2 was small. Following the recommendations of that study, we used a CMM (Coordinate Measuring Machine) instead of the FARO arm for measuring the tooling balls. In addition, a roller cam positioner system replaced the optical movers for moving the quadrupole. With the exception of the quadrupole itself, the system was identical to what will be used in fiducializing the undulator quadrupoles. In this study, we investigate the new vibrating wire set up, including the error associated with each step of fiducialization. A vibrating wire system was constructed to fiducialize the quadrupoles between undulator segments in the LCLS. This note is a continuation of previous work to study the ability of the system to fulfill the fiducialization requirements.

Levashov, Michael Y

2010-12-03

76

Partial discharge characteristics of oil-immersed insulation systems under DC, combined AC-DC and DC reversed polarity voltage  

Microsoft Academic Search

Breakdown characteristics of insulating oil, under combined ac-dc voltage and dc reversed polarity voltage, and partial discharge characteristics of oil-immersed insulation, under combined ac-dc voltage and polarity revesal of dc voltage Were made clear by elementary experiments. After that, a numerical dc field mapping method for electric field analysis of two-dimensional configurations which consist of composite insulation and field mapping

E. Takahashi; Y. Tsutsumi; K. Okuyama; F. Ogata

1976-01-01

77

Malfunction Issue of SiC-SIT Based DC Circuit Breaker in 400V DC Power Distribution Systems for Data Centers  

NASA Astrophysics Data System (ADS)

400V DC power distribution systems for data centers require a fast response DC circuit breaker is required. The semiconductor DC circuit breaker is an important key technology in DC power distribution systems. This paper considers the malfunction of Silicon Carbide- Static Induction Transistor (SiC-SIT) based DC circuit breakers in 400V DC power distribution systems for data centers. The malfunction mechanism is explained, and a solution is proposed. Investigations are achieved by MATLAB/Simulink and experimental verification.

Abe, Seiya; Yang, Sihun; Shoyama, Masahito; Ninomiya, Tamotsu; Matsumoto, Akira; Fukui, Akiyoshi

78

Dc power supplies and hard-tube power conditioning systems  

SciTech Connect

In this lecture, we shall discuss some of the major characteristics of dc power supplies and hard-tube pulsers, along with many of their PCS limiting properties and several of the more powerful vacuum tubes that are currently available for larger hard-tube pulsers systems. The initial topic will be elementary dc power supplies, operating with standard 60 Hz AC input power. The full-wave bridge design will be discussed in detail, illustrating the majority of the significant circuit parameters.

Sarjeant, W.J.

1980-01-01

79

AC versus DC distribution systems- Did we get it right?  

SciTech Connect

We presently enjoy a predominantly ac electrical distribution system, the engineering basis for which was designed over 100 years ago. While ac distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of ac electrical power distribution systems. What opportunities could be obtained by engineering dc distribution into at least portions of our present system? What advantages of the present ac distribution system should be recognized and protected? This paper will focus on distribution within premise and low-voltage distribution systems. Specifically, we will address the conversion efficiency costs of adopting various premise ac and dc distribution system topologies. According to a simple predictive model formulated in this paper, premise residential dc distribution will incur unfavorable total conversion efficiency compared with existing ac premise distribution. However, if a residence is supplied by a fuel cell or another dc generator, the total conversion efficiency within a residential dc distribution system could be similar to, or even better than, that for ac distribution.

Hammerstrom, Donald J.

2007-06-28

80

Compliant control of steer-by-wire systems  

Microsoft Academic Search

Vehicle directional control and driver interaction assemblies have been built to study and implement impedance control strategies on a steer-by-wire system. Adaptive online estimation is used to identify the dynamic parameters of vehicle directional control and driver interaction assemblies. A nonlinear 4 DOF vehicle model, including longitudinal, lateral, yaw and quasi-static roll motions is derived using Newtonian mechanics to simulate

A. Emre Cetin; M. Arif Adli; Duygun Erol Barkana; Haluk Kucuk

2009-01-01

81

A DC motor based cutting tool condition monitoring system  

Microsoft Academic Search

In this paper a cutting tool condition monitoring system for CNC lathes is presented. The system is based on the measurement of the main DC motor current of the lathes. It consists of current and rotation speed sensors, a cutting tool – part touch sensor, analogue memory, amplifiers, filters and a personal computer. The system is capable of functioning in

Tamas Szecsi

1999-01-01

82

Hydrogen Storage Systems Analysis Working Group Meeting Argonne DC Offices  

E-print Network

Hydrogen Storage Systems Analysis Working Group Meeting Argonne DC Offices L'Enfant Plaza and Kristin Deason Sentech, Inc. January 16, 2008 #12;SUMMARY REPORT Hydrogen Storage Systems Analysis Objectives This meeting was one of a continuing series of biannual meetings of the Hydrogen Storage Systems

83

AC versus DC distribution systems- Did we get it right?  

Microsoft Academic Search

We presently enjoy a predominantly ac electrical distribution system, the engineering basis for which was designed over 100 years ago. While ac distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of ac electrical power distribution systems. What opportunities could be obtained by engineering dc

Hammerstrom; Donald J

2007-01-01

84

A bidirectional DC\\/DC power electronic converter for an energy storage device in an autonomous power system  

Microsoft Academic Search

The paper discusses a bidirectional DC\\/DC converter for interfacing an energy storage device in an autonomous power system, which consists of wind turbines and diesel generation units. The operation condition variations, such as switching load, could cause significant dynamics in an autonomous system. An energy storage device can effectively increase the utilization of the renewable energy and improve the capability

Y. Hu; J. Tatler; Z. Chen

2004-01-01

85

A framework for SFC/DC system data analysis  

NASA Technical Reports Server (NTRS)

The Shop Floor Control/Data Collection (SFC/DC) system is one of four major modules of the Integrated Work Control System being implemented at the NASA Kennedy Space Center. The SFC/DC system, which has been in operation approximately one and a half years, collects detailed information regarding the duration of tasks as well as work stoppages duration. This information needs to be effectively analyzed, so as be able to manage the shuttle processing activities under the continuous improvement philosophy. We have studied the contents and form of the SFC/DC database, and based on the results of such study, we have designed a Shop floor Modeling, Analysis, and Reporting Tool (SMART). SMART is a collection of compatible tools (off-the-shelf as well as customized C-based tools) that work cohesively to prepare inputs for the analysis models and process the various models. The feasibility of SMART has been demonstrated through an initial prototype.

Centeno, Martha A.

1993-01-01

86

AC/DC Power Systems with Applications for future Lunar/Mars base and Crew Exploration Vehicle  

NASA Technical Reports Server (NTRS)

ABSTRACT The Power Systems branch at JSC faces a number of complex issues as it readies itself for the President's initiative on future space exploration beyond low earth orbit. Some of these preliminary issues - those dealing with electric power generation and distribution on board Mars-bound vehicle and that on Lunar and Martian surface may be summarized as follows: Type of prime mover - Because solar power may not be readily available on parts of the Lunar/Mars surface and also during the long duration flight to Mars, the primary source of power will most likely be nuclear power (Uranium fuel rods) with a secondary source of fuel cell (Hydrogen supply). The electric power generation source - With nuclear power being the main prime mover, the electric power generation source will most likely be an ac generator at a yet to be determined frequency. Thus, a critical issue is whether the generator should generate at constant or variable frequency. This will decide what type of generator to use - whether it is a synchronous machine, an asynchronous induction machine or a switched reluctance machine. The type of power distribution system - the distribution frequency, number of wires (3- wire, 4-wire or higher), and ac/dc hybridization. Building redundancy and fault tolerance in the generation and distribution sub-systems so that the system is safe; provides 100% availability to critical loads; continues to operate even with faulted sub-systems; and requires minimal maintenance. This report descril_es results of a summer faculty fellowship spent in the Power Systems Branch with the specific aim of investigating some of the lessons learned in electric power generation and usage from the terrestrial power systems industry, the aerospace industry as well as NASA's on-going missions so as to recommend novel surface and vehicle-based power systems architectures in support of future space exploration initiatives. A hybrid ac/dc architecture with source side and load side redundancies and including emergency generators on both ac and dc sides is proposed. The generation frequency is 400 Hz mostly because of the technology maturity at this frequency in the aerospace industry. Power will be distributed to several ac load distribution buses through solid state variable speed, constant frequency converters on the ac side. A segmented dc ring bus supplied from ac/dc converters and with the capability of connecting/disconnecting the segments will supply power to multiple de load distribution buses. The system will have the capability of reverse flow from dc to ac side in the case of an extreme emergency on the main ac generation side.

Chowdhury, Badrul H.

2005-01-01

87

Selection and stability issues associated with a navy shipboard DC zonal electric distribution system  

Microsoft Academic Search

The US Navy is currently investigating the implementation of a DC zonal electric distribution system (DC ZEDS) for the next generation of surface combatant. In replacing the current AC radial distribution system, significant gains can be realized in terms of survivability, weight, manning and cost. DC ZEDS is predicated on having starboard and port DC buses feeding electrical zones delineated

John G. Ciezki; Robert W. Ashton

2000-01-01

88

DC link stabilized field oriented control of electric propulsion systems  

Microsoft Academic Search

Induction motor based electric propulsion systems can be used in a wide variety of applications including locomotives, hybrid electric vehicles, and ships. Field oriented control of these drives is attractive since it allows the torque to be tightly and nearly instantaneously controlled. However, such systems can be prone to negative impedance instability of the DC link. This paper examines this

S. D. Sudhoff; K. A. Corzine; S. F. Glover; H. J. Hegner

1998-01-01

89

A Testing System for Diagnosing Misconceptions in DC Electric Circuits.  

ERIC Educational Resources Information Center

Outlines a test-based diagnosis system for misconceptions in DC electric circuits and its three parts: problem library, problem selector and diagnoser. Discusses misconception discrimination and diagnosis theories, and reports the system supports satisfactory diagnosis. Includes an analysis of nine student misconceptions about electrical circuits…

Chang, Kuo-En; Liu, Sei-Hua; Chen, Sei-Wang

1998-01-01

90

Ship Propulsion AC\\/DC Conversion System Modeling and Design  

Microsoft Academic Search

This paper presents the detailed physics-based model and design of a high voltage high power AC\\/DC power conversion system comprising a 3 to 12 phase transformer and a 24 pulse thyristor controlled rectifier. System level modeling is critical during the multi-year design of the 30-50 MW system. The goal of the modeling effort is to avoid re-designing the system which

Giovanna Oriti; Rob M. Cuzner

2006-01-01

91

A wire scanner system for characterizing the BNL energy recovery LINAC beam position monitor system  

SciTech Connect

A stepper motor controlled wire scanner system has recently been modified to support testing of the Brookhaven National Laboratory (BNL) Collider-Accelerator department's Energy Recovery Linac (ERL) beam position monitor (BPM) system. The ERL BPM consists of four 9.33 mm diameter buttons mounted at 90 degree spacing in a cube with 1.875 inch inside diameter. The buttons were designed by BNL and fabricated by Times Microwave Systems. Libera brilliance single pass BPM electronic modules with 700 MHz bandpass filter, manufactured by Instrumentation Technologies, will be used to measure the transverse beam positions at 14 locations around the ERL. The wire scanner assembly provides the ability to measure the BPM button response to a pulsed wire, and evaluate and calibrate the Libera position measurement electronics. A description of the wire scanner system and test result data will be presented.

Michnoff R.; Biscardi, C.; Cerniglia, P.; Degen, C.; Gassner, D.; Hoff, L.; Hulsart, R.

2012-04-15

92

Novel calibration system with sparse wires for CMB polarization receivers  

SciTech Connect

B-modes in the cosmic microwave background (CMB) polarization is a smoking gun signature of the inflationary universe. To achieve better sensitivity to this faint signal, CMB polarization experiments aim to maximize the number of detector elements, resulting in a large focal plane receiver. Detector calibration of the polarization response becomes essential. It is extremely useful to be able to calibrate 'simultaneously' all detectors on the large focal plane. We developed a novel calibration system that rotates a large 'sparse' grid of metal wires, in front of and fully covering the field of view of the focal plane receiver. Polarized radiation is created via the reflection of ambient temperature from the wire surface. Since the detector has a finite beam size, the observed signal is smeared according to the beam property. The resulting smeared polarized radiation has a reasonable intensity (a few Kelvin or less) compared to the sky temperature ({approx}10 K observing condition). The system played a successful role for receiver calibration of QUIET, a CMB polarization experiment located in the Atacama desert in Chile. The successful performance revealed that this system is applicable to other experiments based on different technologies, e.g. TES bolometers.

Tajima, O.; /KEK, Tsukuba /Chicago U., KICP; Nguyen, H.; /Fermilab; Bischoff, C.; /Chicago U., KICP /Harvard-Smithsonian Ctr. Astrophys.; Brizius, A.; Buder, I.; Kusaka, A. /Chicago U., KICP

2011-07-01

93

Brushless DC Motor Propulsion Using Synchronous Motors for Transit Systems  

Microsoft Academic Search

In this paper, a brushless dc motor propulsion system using synchronous motors is described which is suitable for transit applications. The propulsion system consists of two-quadrant transistorized front-end chopper and a three-phase transistorized inverter (forming the electronic commutator for the synchronous machine phase currents) to provide both controlled propulsion and regenerative braking. The control scheme makes the system operate stably

W. R. PEARSONAND; Paresh C. Sen

1984-01-01

94

Losses in pulsed DC fusing systems  

Microsoft Academic Search

Determining losses in an energy system can be more frustrating than the original design process of that system. A fusing technique utilizing a thin film planar geometry is currently being developed at the Energy Systems Institute as a pulsed light and fusing source. The thin film in question is capacitor grade, metallized polypropylene film. The film is seven microns thick

J. D. Buneo; J. L. Zirnheld; K. M. Burke; J. B. Kirkland; E. M. Halstead; A. J. Halstead; W. J. Sarjeant

2003-01-01

95

A magnetic-less DC-DC converter for dual-voltage automotive systems  

Microsoft Academic Search

The automotive industry is moving toward 42 V to meet more electrical needs. Several dual-voltage (42 and 14 V) architectures have been proposed for the transition and accommodation of 14-V loads. A DC-DC converter that connects the 42 and 14 V is one key device in any dual-voltage architecture. This paper presents a compact, efficient, magnetic-less bidirectional DC-DC converter for

Fang Zheng Peng; Fan Zhang; Zhaoming Qian

2003-01-01

96

Feasibility analysis of the application and positioning of DC HTS FCL in a DC microgrid through modeling and simulation using Simulink and SimPowerSystem  

NASA Astrophysics Data System (ADS)

DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.

Khan, U. A.; Shin, W. J.; Seong, J. K.; Oh, S. H.; Lee, S. H.; Lee, B. W.

2011-11-01

97

System For Characterizing Three-Phase Brushless dc Motors  

NASA Technical Reports Server (NTRS)

System of electronic hardware and software developed to automate measurements and calculations needed to characterize electromechanical performances of three-phase brushless dc motors, associated shaft-angle sensors needed for commutation, and associated brushless tachometers. System quickly takes measurements on all three phases of motor, tachometer, and shaft-angle sensor simultaneously and processes measurements into performance data. Also useful in development and testing of motors with not only three phases but also two, four, or more phases.

Howard, David E.; Smith, Dennis A.

1996-01-01

98

Digital simulation of AC\\/DC hybrid transmission system  

Microsoft Academic Search

For the 3000 MW Gui-Guang HVDC power transmission project, the NETOMAC (Network Torsion Machine Control) program was used to simulate the complete power system of South China, which includes AC\\/DC hybrid transmission systems. The simulation results of the NETOMAC program are compared with the results from the BPA (Bonneville Power Administration) program used by the owner of the Gui-Guang HVDC

Jing Yong; Wu Xiaochen; Du Zhongming; Jin Xiaoming; Wang Yuhong; D. H. Zhang; J. Rittiger

2002-01-01

99

Electromagnetic Energy Harvesting Circuit With Feedforward and Feedback DC–DC PWM Boost Converter for Vibration Power Generator System  

Microsoft Academic Search

This paper presents an integrated vibration power generator system. The system consists of a mini electromagnetic vibration power generator and a highly efficient energy harvesting circuit implemented on a minute printed circuit board and a 0.35-mum CMOS integrated chip. By introducing a feedback control into the dc-dc pulsewidth modulation (PWM) boost converter with feedforward control, the energy harvesting circuit can

Xinping Cao; Wen-Jen Chiang; Ya-Chin King; Yi-Kuen Lee

2007-01-01

100

On-line system for measuring electrophysical characteristics of superconducting wires  

Microsoft Academic Search

A system for measuring electrophysical characteristics of superconducting wires, containing a set of SUMMA modules controlled by the Elektronika-60 microcomputer is described. The system is intended for measuring magnetization, dynamic losses and critical current density in superconducting wires. The system structure, measurement methods and algorithm, and the results obtained are presented.

A. G. Aleksandrov; M. G. Vybornov; A. G. Goremykin

1987-01-01

101

Electrostatic coalescence system with independent AC and DC hydrophilic electrodes  

SciTech Connect

An improved electrostatic coalescence system is provided in which independent AC and DC hydrophilic electrodes are employed to provide more complete dehydration of an oil emulsion. The AC field is produced between an AC electrode array and the water-oil interface wherein the AC electrode array is positioned parallel to the interface which acts as a grounded electrode. The emulsion is introduced into the AC field in an evenly distributed manner at the interface. The AC field promotes drop-drop and drop-interface coalescence of the water phase in the entering emulsion. The continuous oil phase passes upward through the perforated AC electrode array and enters a strong DC field produced between closely spaced DC electrodes in which small dispersed droplets of water entrained in the continuous phase are removed primarily by collection at hydrophilic DC electrodes. Large droplets of water collected by the electrodes migrate downward through the AC electrode array to the interface. All phase separation mechanisms are utilized to accomplish more complete phase separation.

Hovarongkura, A. David (Arlington, VA); Henry, Jr., Joseph D. (Morgantown, WV)

1981-01-01

102

A Multiphase, Modular, Bidirectional, Triple-Voltage DC-DC Converter Power Systems  

SciTech Connect

Electrical power systems in future hybrid and fuel cell vehicles may employ three voltage [14 V, 42 V, and high voltage (HV)] nets. These will be necessary to accommodate existing 14-V loads as well as efficiently handle new heavy loads at the 42-V net and a traction drive on the HV bus. A low-cost DC-DC converter was proposed for connecting the three voltage nets. It minimizes the number of switches and their associated gate driver components by using two half-bridges and a high-frequency transformer. Another salient feature is that the half bridge on the 42-V bus is also utilized to provide the 14-V bus by operating at duty ratios around an atypical value of 1/3. Moreover, it makes use of the parasitic capacitance of the switches and the transformer leakage inductance for soft switching. The use of half bridges makes the topology well suited for interleaved multiphase modular configurations as a means to increase the power level because the capacitor legs can be shared. This paper presents simulation and experimental results on an interleaved two-phase arrangement rated at 4.5 kW. Also discussed are the benefits of operating with an atypical duty ratio on the transformer and a preferred multiphase configuration to minimize capacitor ripple currents.

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

2008-01-01

103

Efficient Design in a DC to DC Converter Unit  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

104

Multi-kw dc power distribution system study program  

NASA Technical Reports Server (NTRS)

The first phase of the Multi-kw dc Power Distribution Technology Program is reported and involves the test and evaluation of a technology breadboard in a specifically designed test facility according to design concepts developed in a previous study on space vehicle electrical power processing, distribution, and control. The static and dynamic performance, fault isolation, reliability, electromagnetic interference characterisitics, and operability factors of high distribution systems were studied in order to gain a technology base for the use of high voltage dc systems in future aerospace vehicles. Detailed technical descriptions are presented and include data for the following: (1) dynamic interactions due to operation of solid state and electromechanical switchgear; (2) multiplexed and computer controlled supervision and checkout methods; (3) pulse width modulator design; and (4) cable design factors.

Berkery, E. A.; Krausz, A.

1974-01-01

105

A 64-channel DC-SQUID magnetometer system  

Microsoft Academic Search

A modular 64-channel SQUID magnetometer system has been developed for biomagnetic applications. The square-shaped double washer DC-SQUIDs are fabricated by thin film technology based on the Nb metal process. The signal is detected by a first-order planar gradiometer with counter-wound 10 mm square-shaped coils and a baseline length of 40 mm. The SQUIDs are operated in a flux locked mode.

K. Okajima; T. Komuro; N. Harada; A. Adachi; M. Ueda; A. Kandori; G. Uehara; H. Kado

1993-01-01

106

1500 V DC traction system for the North East Line  

Microsoft Academic Search

The North East Line (NEL) traction system is operating at 1500 V DC obtained from a 22 kV distribution network supplying 16 stations, a depot and a route length of 20 km. There are two power intake points from the PowerGrid, one at the Sengkang Depot (66 kV) and the other at the Stamford Intake (22 kV). Inverters are installed

E. J. Goh; K. N. Chu; N. K. Ng

2004-01-01

107

DC and Pulsed Septa for the LNLS UVX Injection System  

NASA Astrophysics Data System (ADS)

The design, construction and installation of a pulsed thin septum and a d.c. thick septum for the LNLS UVX injection system is presented. The injection system uses two septa and three kickers to inject the 120 MeV electron beam coming from the Linac into the storage ring. The present system uses two d.c. septa. A pulsed thin septum was constructed in order to reduce the septum wall thickness from the present 5.5 mm to a thinner 1.5 mm septum. The passive septum wall consists of 1-mm-thick copper and of a 0.5-mm-thick magnetic screen. The magnet is driven by a 10-kHz, 1.6-kA half sine wave current pulse. The 0.4 meter ferrite core is housed inside vacuum and deflects the incoming beam by 52 mrad (0.09 T). A new d.c. thick septum has also been constructed in order to fit the septa to the already installed transport line.

Farias, Ruy H. A.; Ferreira, M. J.; Neuenschwander, R. T.; Rafael, F. S.

1997-05-01

108

CSMP (Continuous System Modeling Program) modeling of brushless DC motors  

NASA Astrophysics Data System (ADS)

Recent improvements in rare earth magnets have made it possible to construct strong, lightweight, high horsepower DC motors. This has occasioned a reassessment of electromechanical actuators as alternatives to comparable pneumatic and hydraulic systems for use in flight control actuators for tactical missiles. This thesis develops a low-order mathematical model for the simulation and analysis of brushless DC motor performance. This model is implemented in CSMP language. It is used to predict such motor performance curves as speed, current and power versus torque. Electronic commutation based on Hall effect sensor positional feedback is simulated. Steady state motor behavior is studied under both constant and variable air gap flux conditions. The variable flux takes two different forms. In the first case, the flux is varied as a simple sinusoid. In the second case, the flux is varied as the sum of a sinusoid and one of its harmonics.

Thomas, S. M.

1984-09-01

109

Genetic control of wiring specificity in the fly olfactory system.  

PubMed

Precise connections established between pre- and postsynaptic partners during development are essential for the proper function of the nervous system. The olfactory system detects a wide variety of odorants and processes the information in a precisely connected neural circuit. A common feature of the olfactory systems from insects to mammals is that the olfactory receptor neurons (ORNs) expressing the same odorant receptor make one-to-one connections with a single class of second-order olfactory projection neurons (PNs). This represents one of the most striking examples of targeting specificity in developmental neurobiology. Recent studies have uncovered central roles of transmembrane and secreted proteins in organizing this one-to-one connection specificity in the olfactory system. Here, we review recent advances in the understanding of how this wiring specificity is genetically controlled and focus on the mechanisms by which transmembrane and secreted proteins regulate different stages of the Drosophila olfactory circuit assembly in a coordinated manner. We also discuss how combinatorial coding, redundancy, and error-correcting ability could contribute to constructing a complex neural circuit in general. PMID:24395823

Hong, Weizhe; Luo, Liqun

2014-01-01

110

Modelling, Simulation and Construction of a DC/DC Boost Power Converter: A School Experimental System  

ERIC Educational Resources Information Center

We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…

Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.

2012-01-01

111

Plasma chemistry in wire chambers  

SciTech Connect

The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

Wise, J.

1990-05-01

112

X-wing fly-by-wire vehicle management system  

NASA Technical Reports Server (NTRS)

A complete, computer based, vehicle management system (VMS) for X-Wing aircraft using digital fly-by-wire technology controlling many subsystems and providing functions beyond the classical aircraft flight control system. The vehicle management system receives input signals from a multiplicity of sensors and provides commands to a large number of actuators controlling many subsystems. The VMS includes--segregating flight critical and mission critical factors and providing a greater level of back-up or redundancy for the former; centralizing the computation of functions utilized by several subsystems (e.g. air data, rotor speed, etc.); integrating the control of the flight control functions, the compressor control, the rotor conversion control, vibration alleviation by higher harmonic control, engine power anticipation and self-test, all in the same flight control computer (FCC) hardware units. The VMS uses equivalent redundancy techniques to attain quadruple equivalency levels; includes alternate modes of operation and recovery means to back-up any functions which fail; and uses back-up control software for software redundancy.

Fischer, Jr., William C. (Inventor)

1990-01-01

113

DC Bus Regulation with a Flywheel Energy Storage System  

NASA Technical Reports Server (NTRS)

This paper describes the DC bus regulation control algorithm for the NASA flywheel energy storage system during charge, charge reduction and discharge modes of operation. The algorithm was experimentally verified with results given in a previous paper. This paper presents the necessary models for simulation with detailed block diagrams of the controller algorithm. It is shown that the flywheel system and the controller can be modeled in three levels of detail depending on the type of analysis required. The three models are explained and then compared using simulation results.

Kenny, Barbara H.; Kascak, Peter E.

2003-01-01

114

Heavy ion beam scanning system of DC-110 accelerator  

NASA Astrophysics Data System (ADS)

A heavy ion acceleration complex for industrial applications based on the DC-110 cyclotron has been developed at the Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. It is planned to irradiate polymer films with a width of up to 600 mm at this complex. This paper presents a design of a system for scanning heavy ion beam which offers uniform film irradiation at a beam energy of up to 2.5 MeV/nucleon. The general concept of the two-channel scanning system and the design of the main deflecting magnets are described.

Gikal, B. N.; Gorbachev, E. V.; Lebedev, N. I.; Fateev, A. A.

2010-12-01

115

A Study of Steering System Model for Steering Feel's Improvement of Steer-by-Wire System  

Microsoft Academic Search

Steer-By-Wire(SBW) system is the one of the advanced technologies that will be applied to steering system for the next generation's vehicles. It removes mechanical linkages between steering wheel and front wheels. As a result, SBW enhances controllability of vehicle dynamic characteristic and safety of car crash, and simplifies vehicle design process. The main purpose of this study is to focus

Kim Ilhwan; Lee Jonghyun

116

Virtual Instrument Systems in Reality (VISIR) for Remote Wiring and Measurement of Electronic Circuits on Breadboard  

ERIC Educational Resources Information Center

This paper reports on a state-of-the-art remote laboratory project called Virtual Instrument Systems in Reality (VISIR). VISIR allows wiring and measuring of electronic circuits remotely on a virtual workbench that replicates physical circuit breadboards. The wiring mechanism is developed by means of a relay switching matrix connected to a PCI…

Tawfik, M.; Sancristobal, E.; Martin, S.; Gil, R.; Diaz, G.; Colmenar, A.; Peire, J.; Castro, M.; Nilsson, K.; Zackrisson, J.; Hakansson, L.; Gustavsson, I.

2013-01-01

117

A trajectory tracking steer-by-wire control system for ground vehicles  

Microsoft Academic Search

The application of multi-disciplinary automotive technologies to hybrid vehicles has resulted in the integration of alternative propulsion sources and drive-by-wire components for enhanced ground vehicle performance, fuel economy, and occupant safety. The integration of steer-by-wire systems in vehicles facilitates autonomous and semi-autonomous operations, better lateral vehicle behavior, an adjustable steering \\

Pradeep Setlur; John R. Wagner; Darren M. Dawson; David Braganza

2006-01-01

118

Adiabatic spin pumping in interacting quantum wires and mesoscopic systems  

Microsoft Academic Search

Periodic variations in time of interactions that locally break spin-rotation symmetry generates a spin current. In general such a spin current is itself alternating in time. A suitable choice of tunable symmetry-breaking perturbations can, however, lead to a dc spin current in response to their periodic temporal variation. This mechanism of pumping is shown to generate a dc spin current

Prashant Sharma

2004-01-01

119

Toward a reduced-wire readout system for ultrasound imaging.  

PubMed

We present a system-on-a-chip (SoC) for use in high-frequency capacitive micromachined ultrasonic transducer (CMUT) imaging systems. This SoC consists of trans-impedance amplifiers (TIA), delay locked loop (DLL) based clock multiplier, quadrature sampler, and pulse width modulator (PWM). The SoC down converts RF echo signal to baseband by quadrature sampling which facilitates modulation. To send data through a 1.6 m wire in the catheter which has limited bandwidth and is vulnerable to noise, the SoC creates a pseudo-digital PWM signal which can be used for back telemetry or wireless readout of the RF data. In this implementation, using a 0.35-?m std. CMOS process, the TIA and single-to-differential (STD) converter had 45 MHz bandwidth, the quadrature sampler had 10.1 dB conversion gain, and the PWM had 5-bit ENoB. Preliminary results verified front-end functionality, and the power consumption of a TIA, STD, quadrature sampler, PWM, and clock multiplier was 26 mW from a 3 V supply. PMID:25571135

Jaemyung Lim; Arkan, Evren F; Degertekin, F Levent; Ghovanloo, Maysam

2014-08-01

120

47 CFR 68.213 - Installation of other than “fully protected” non-system simple customer premises wiring.  

Code of Federal Regulations, 2012 CFR

...than âfully protectedâ non-system simple customer premises wiring...fully protected” non-system simple customer premises wiring...business telephone service. More complex installations of wiring for...line services, for use with systems such as PBX and key...

2012-10-01

121

47 CFR 68.213 - Installation of other than “fully protected” non-system simple customer premises wiring.  

Code of Federal Regulations, 2013 CFR

...than âfully protectedâ non-system simple customer premises wiring...fully protected” non-system simple customer premises wiring...business telephone service. More complex installations of wiring for...line services, for use with systems such as PBX and key...

2013-10-01

122

47 CFR 68.213 - Installation of other than “fully protected” non-system simple customer premises wiring.  

Code of Federal Regulations, 2014 CFR

...than âfully protectedâ non-system simple customer premises wiring...fully protected” non-system simple customer premises wiring...business telephone service. More complex installations of wiring for...line services, for use with systems such as PBX and key...

2014-10-01

123

A One Chip Hardened Solution for High Speed SpaceWire System Implementations. Session: Components  

NASA Technical Reports Server (NTRS)

An Application Specific Integrated Circuit (ASIC) that implements the SpaceWire protocol has been developed in a radiation hardened 0.25 micron CMOS technology. This effort began in March 2003 as a joint development between the NASA Goddard Space Flight Center (GSFC) and BAE Systems. The BAE Systems SpaceWire ASIC is comprised entirely of reusable core elements, many of which are already flight-proven. It incorporates a router with 4 SpaceWire ports and two local ports, dual PC1 bus interfaces, a microcontroller, 32KB of internal memory, and a memory controller for additional external memory use. The SpaceWire cores are also reused in other ASICs under development. The SpaceWire ASIC is planned for use on the Geostationary Operational Environmental Satellites (GOES)-R, the Lunar Reconnaissance Orbiter (LRO) and other missions. Engineering and flight parts have been delivered to programs and users. This paper reviews the SpaceWire protocol and those elements of it that have been built into the current and next SpaceWire reusable cores and features within the core that go beyond the current standard and can be enabled or disabled by the user. The adaptation of SpaceWire to BAE Systems' On Chip Bus (OCB) for compatibility with the other reusable cores will be reviewed and highlighted. Optional configurations within user systems and test boards will be shown. The physical implementation of the design will be described and test results from the hardware will be discussed. Application of this ASIC and other ASICs containing the SpaceWire cores and embedded microcontroller to Plug and Play and reconfigurable implementations will be described. Finally, the BAE Systems roadmap for SpaceWire developments will be updated, including some products already in design as well as longer term plans.

Marshall, Joseph R.; Berger, Richard W.; Rakow, Glenn P.

2007-01-01

124

Multi-KW dc distribution system technology research study  

NASA Technical Reports Server (NTRS)

The Multi-KW DC Distribution System Technology Research Study is the third phase of the NASA/MSFC study program. The purpose of this contract was to complete the design of the integrated technology test facility, provide test planning, support test operations and evaluate test results. The subjet of this study is a continuation of this contract. The purpose of this continuation is to study and analyze high voltage system safety, to determine optimum voltage levels versus power, to identify power distribution system components which require development for higher voltage systems and finally to determine what modifications must be made to the Power Distribution System Simulator (PDSS) to demonstrate 300 Vdc distribution capability.

Dawson, S. G.

1978-01-01

125

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

Microsoft Academic Search

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

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

1994-01-01

126

Development of a DC propulsion system for an electric vehicle  

NASA Technical Reports Server (NTRS)

The suitability of the Eaton automatically shifted mechanical transaxle concept for use in a near-term dc powered electric vehicle is evaluated. A prototype dc propulsion system for a passenger electric vehicle was designed, fabricated, tested, installed in a modified Mercury Lynx vehicle and track tested at the contractor's site. The system consisted of a two-axis, three-speed, automatically-shifted mechanical transaxle, 15.2 Kw rated, separately excited traction motor, and a transistorized motor controller with a single chopper providing limited armature current below motor base speed and full range field control above base speed at up to twice rated motor current. The controller utilized a microprocessor to perform motor and vehicle speed monitoring and shift sequencing by means of solenoids applying hydraulic pressure to the transaxle clutches. Bench dynamometer and track testing was performed. Track testing showed best system efficiency for steady-state cruising speeds of 65-80 Km/Hz (40-50 mph). Test results include acceleration, steady speed and SAE J227A/D cycle energy consumption, braking tests and coast down to characterize the vehicle road load.

Kelledes, W. L.

1984-01-01

127

Manchester Coding Option for SpaceWire: Providing Choices for System Level Design  

NASA Technical Reports Server (NTRS)

This paper proposes an optional coding scheme for SpaceWire in lieu of the current Data Strobe scheme for three reasons. First reason is to provide a straightforward method for electrical isolation of the interface; secondly to provide ability to reduce the mass and bend radius of the SpaceWire cable; and thirdly to provide a means for a common physical layer over which multiple spacecraft onboard data link protocols could operate for a wide range of data rates. The intent is to accomplish these goals without significant change to existing SpaceWire design investments. The ability to optionally use Manchester coding in place of the current Data Strobe coding provides the ability to DC balanced the signal transitions unlike the SpaceWire Data Strobe coding; and therefore the ability to isolate the electrical interface without concern. Additionally, because the Manchester code has the clock and data encoded on the same signal, the number of wires of the existing SpaceWire cable could be optionally reduced by 50. This reduction could be an important consideration for many users of SpaceWire as indicated by the already existing effort underway by the SpaceWire working group to reduce the cable mass and bend radius by elimination of shields. However, reducing the signal count by half would provide even greater gains. It is proposed to restrict the data rate for the optional Manchester coding to a fixed data rate of 10 Megabits per second (Mbps) in order to make the necessary changes simple and still able to run in current radiation tolerant Field Programmable Gate Arrays (FPGAs). Even with this constraint, 10 Mbps will meet many applications where SpaceWire is used. These include command and control applications and many instruments applications with have moderate data rate. For most NASA flight implementations, SpaceWire designs are in rad-tolerant FPGAs, and the desire to preserve the heritage design investment is important for cost and risk considerations. The Manchester coding option can be accommodated in existing designs with only changes to the FPGA.

Rakow, Glenn; Kisin, Alex

2014-01-01

128

Evaluating the communication impact on quality of service in steer-by-wire systems  

Microsoft Academic Search

X-by-Wire is a generic term referring to the replacement of mechanical or hydraulic systems, such as braking or steering, by electronic ones. The control of x-by-wire systems depends on communication network (like CAN, TTCAN or FlexRay), it must meet not only the control performance, but also the real-time requirements. This paper presents a system approach for evaluating the communication impact

Fang Li; Lifang Wang; Chenglin Liao

2008-01-01

129

Beam Emittance Measurement with Laser Wire Scanners in the ILC Beam Delivery System  

SciTech Connect

Accurate measurement of the beam phase-space is essential for the next generation of electron accelerators. A scheme for beam optics optimization and beam matrix reconstruction algorithms for the diagnostics section of the beam delivery system of the International Linear Collider based on laser-wire beam profile monitors are discussed. Possible modes of operation of the laser-wire system together with their corresponding performance are presented. Based on these results, prospects for reconstructing the ILC beam emittance from representative laser-wire beam size measurements are evaluated.

Agapov, I.; /CERN; Blair, G.A.; /Royal Holloway, U. of London; Woodley, M.; /SLAC

2008-02-01

130

Low speed phaselock speed control system. [for brushless dc motor  

NASA Technical Reports Server (NTRS)

A motor speed control system for an electronically commutated brushless dc motor is provided which includes a phaselock loop with bidirectional torque control for locking the frequency output of a high density encoder, responsive to actual speed conditions, to a reference frequency signal, corresponding to the desired speed. The system includes a phase comparator, which produces an output in accordance with the difference in phase between the reference and encoder frequency signals, and an integrator-digital-to-analog converter unit, which converts the comparator output into an analog error signal voltage. Compensation circuitry, including a biasing means, is provided to convert the analog error signal voltage to a bidirectional error signal voltage which is utilized by an absolute value amplifier, rotational decoder, power amplifier-commutators, and an arrangement of commutation circuitry.

Fulcher, R. W.; Sudey, J. (inventors)

1975-01-01

131

Application of Superconducting Power Cables to DC Electric Railway Systems  

NASA Astrophysics Data System (ADS)

For novel design and efficient operation of next-generation DC electric railway systems, especially for their substantial energy saving, we have studied the feasibility of applying superconducting power cables to them. In this paper it is assumed that a superconducting power cable is applied to connect substations supplying electric power to trains. An analysis model line was described by an electric circuit, which was analyzed with MATLAB-Simulink. From the calculated voltages and currents of the circuit, the regenerative brake and the energy losses were estimated. In addition, assuming the heat loads of superconducting power cables and the cryogenic efficiency, the energy saving of the total system was evaluated. The results show that the introduction of superconducting power cables could achieve the improved use of regenerative brake, the loss reduction, the decreased number of substations, the reduced maintenance, etc.

Ohsaki, Hiroyuki; Lv, Zhen; Sekino, Masaki; Tomita, Masaru

132

Dynamic Stiffness of a Railway Overhead Wire System and its Effect on PANTOGRAPH-CATENARY System Dynamics  

NASA Astrophysics Data System (ADS)

For an electrical railway overhead wire system there are two main factors which crucially affect the quality of current collection. One is the spatial stiffness variation of the overhead wire along each span and the other is the flexural wave motion in the wire. In this paper a periodically excited single-degree-of-freedom (SDOF) model of a combined pantograph-catenary system is introduced and its basic dynamic behaviour is discussed. To investigate the effect of wave propagation in the overhead wire on vibration of the pantograph the dynamic stiffness of the catenary is introduced into the model. The dynamic stiffness of the catenary is determined by representing the overhead wire system as an infinite periodically spring-supported string. The results show that the dynamic stiffness of the catenary varies with train speed and its effect on the performance of the pantograph-catenary system is discussed.

Wu, T. X.; Brennan, M. J.

1999-01-01

133

A Five-Phase Brushless DC-Machine Direct Drive System EPE Journal Vol. 14 no  

E-print Network

A Five-Phase Brushless DC-Machine Direct Drive System EPE Journal Vol. 14 no 3 August 2004 15 implementation of a high-torque, low- speed, multiphase, permanent magnet, brushless dc-machine. The paper machine in hub-wheel systems ­ high-torque low-speed motors can directly drive systems, avoi- ding

Simões, Marcelo Godoy

134

High-speed micro electrode tool fabrication by a twin-wire EDM system  

NASA Astrophysics Data System (ADS)

This paper describes a new machining process which combines twin-electro-wire together with two electro discharge circuits to rapidly fabricate micro electrode tools. The results show that transistor electro discharge and RC electro discharge circuits coexist to fabricate micro tools with rough and finish machining both on the same machine. Compared to conventional wire electro discharge grinding (WEDG) technology, a twin-wire EDM system that combines rough and finish machining into one process allows the efficient fabrication of micro tools. This high-speed micro tool fabrication process can be applied not only to micro electrode machining but also to micro punching tool and micro probing tips machining.

Sheu, Dong-Yea

2008-10-01

135

Discharging a DC bus capacitor of an electrical converter system  

DOEpatents

A system and method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle are presented here. The method begins by electrically shorting the AC interface of the converter after an AC energy source is disconnected from the AC interface. The method continues by arranging a plurality of switching elements of a second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of an isolation module, through an inductive element, and to a second terminal of the isolation module. The method also modulates a plurality of switching elements of a first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge a DC bus capacitor.

Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M

2014-10-14

136

Corridor-Based Emergency Evacuation System for Washington, D.C.: System Development and Case Study  

Microsoft Academic Search

The evacuation of large municipal areas in an efficient manner during emergencies and disasters is one of the critical tasks of emergency management agencies. This paper presents a corridor-based emergency evacuation system and an example application of the system for the Washington, D.C., metropolitan area. The proposed system features flexibility by accounting for various critical issues associated with both planning

Yue Liu; Gang-Len Chang; Ying Liu; Xiaorong Lai

2008-01-01

137

Power system monitoring and source control of the Space Station Freedom DC power system testbed  

Microsoft Academic Search

Unlike a terrestrial electric utility which can purchase power from a neighboring utility, the Space Station Freedom (SSF) has strictly limited energy resources; as a result, source control, system monitoring, system protection, and load management are essential to the safe and efficient operation of the SSF Electric Power System (EPS). These functions are being evaluated in the DC Power Management

Greg L. Kimnach; Anastacio N. Baez

1992-01-01

138

Power system monitoring and source control of the Space Station Freedom dc-power system testbed  

Microsoft Academic Search

Unlike a terrestrial electric utility which can purchase power from a neighboring utility, the Space Station Freedom (SSF) has strictly limited energy resources; as a result, source control, system monitoring, system protection, and load management are essential to the safe and efficient operation of the SSF Electric Power System (EPS). These functions are being evaluated in the dc Power Management

Greg L. Kimnach; Anastacio N. Baez

1992-01-01

139

Advanced medium-voltage bidirectional dc-dc conversion systems for future electric energy delivery and management systems  

NASA Astrophysics Data System (ADS)

The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed generation systems Furthermore, power electronics systems can provide additional intelligent energy management, grid stability and power quality capabilities. Medium-voltage isolated dc-dc converter will become one of the key interfaces for grid components with moderate power ratings. To address the demand of medium voltage (MV) and high power capability for future electric energy delivery and management systems, the power electronics community and industry have been reacting in two different ways: developing semiconductor technology or directly connecting devices in series/parallel to reach higher nominal voltages and currents while maintaining conventional converter topologies; and by developing new converter topologies with traditional semiconductor technology, known as multilevel converters or modular converters. The modular approach uses the well-known, mature, and cheaper power semiconductor devices by adopting new converter topologies. The main advantages of the modular approach include: significant improvement in reliability by introducing desired level of redundancy; standardization of components leading to reduction in manufacturing cost and time; power systems can be easily reconfigured to support varying input-output specifications; and possibly higher efficiency and power density of the overall system. Input-series output-parallel (ISOP) modular configuration is a good choice to realize MV to low voltage (LV) conversion for utility application. However, challenges still remain. First of all, for the high-frequency MV utility application, the low switching loss and conduction loss are must-haves for high efficiency, while bidirectional power flow capability is a must for power management requirement. To address the demand, the phase-shift dual-halfbridge (DHB) is proposed as the constituent module of ISOP configuration for MV application. The proposed ISOP DHB converter employs zero-voltage-switching (ZVS) technique combined with LV MOSFETs to achieve low switching and conduction losses under high frequency operation, and therefore high efficiency and high power density, and bidirectional power flow as well. Secondly, a large load range of high efficiency is desired rather than only a specific load point due to the continuous operation and large load variation range of utility application, which is of high importance because of the rising energy cost. This work proposes a novel DHB converter with an adaptive commutation inductor. By utilizing an adaptive inductor as the main energy transfer element, the output power can be controlled by not only the phase shift but also the commutation inductance, which allows the circulating energy to be optimized for different load conditions to maintain ZVS under light load conditions and minimize additional conduction losses under heavy load conditions as well. As a result, the efficiency at both light and heavy load can be significantly improved compared with the conventional DHB converter, and therefore extended high-efficiency range can be achieved. In addition, current stress of switch devices can be reduced. The theoretical analysis is presented and validated by the experimental results on a 50 kHz, 1 kW dc-dc converter module. Thirdly, input-voltage sharing and output-current sharing are critical to assure the advantages of the ISOP modular configuration. To solve this issue, an identically distributed control scheme is proposed in this work. The proposed control scheme, using only one distributed voltage loop to realize both input-voltage and output-current sharing, provides plug-and-play capability, possible high-level fault tolerance, and easy implementatio

Fan, Haifeng

2011-12-01

140

A high quality power supply system with DC smart grid  

Microsoft Academic Search

Due to the depletion of energy resources and consideration of the natural environment, introduction of natural energy facilities have been increasing yearly. However, due to the fluctuating power from renewable energy sources, the DC bus voltage fluctuation of DC grid becomes problematic. At the same time, there has been a increase in electrification house or residence and electric vehicles in

Kyohei Kurohane; Tomonobu Senjyu; Atsushi Yona; Naomitsu Urasaki; Endusa Billy Muhando; Toshihisa Funabashi

2010-01-01

141

A Novel Structure for Three-Phase Four-Wire Distribution System Utilizing Unified Power Quality Conditioner (UPQC)  

Microsoft Academic Search

This paper presents a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC). The 3P4W system is realized from a three-phase three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents

Vinod Khadkikar; Ambrish Chandra

2009-01-01

142

Novel DC ring topology and protection system - a comprehensive solution for mega city power grids  

NASA Astrophysics Data System (ADS)

The development of mega cities leads to increased load concentration and brings additional challenges to managing the electrical grid while keeping power available for critical loads. Techniques using FACTS devices are being applied to alleviate power management difficulties and to confine faults in their originating areas in order to limit the risk of cascading failures in the grid. The addition of many FACTS devices often results in control and protection coordination difficulties, power oscillations between connected networks, subsynchronous resonance problems, and torsional interactions with nearby generator units. The most effective solution is obtained when the individual AC subsystems representing sources and loads are decoupled so a fault in a given subsystem is not propagated to another subsystem. This solution can be achieved by the deployment of a DC system where power sources and loads are connected to the DC bus through voltage source converters. For a mega city, this would be conceived as a DC ring feeding multiple loads and connected to remote and local power sources. Unfortunately, the lack of fast DC circuit breakers has been one of the key issues affecting extensive applications of DC systems with common DC buses; a DC fault would discharge all the capacitors of the DC bus and cause delays in system recovery and possibly a wide system collapse. In this research, I provide a comprehensive solution to mega city power grid problems by proposing a DC system topology that enables grid expansions without affecting existing protection settings or changing existing AC breaker ratings. I also propose the means for protecting the DC system by designing a fast DC breaker and developing a control algorithm capable of isolating DC faults without blocking converter stations or depleting DC bus capacitors. My contribution is three folds: (1) I modeled and simulated Shanghai power grid and performed a study to identify short circuit and voltage stability problems using data provided by ABB corporate research located in China. I built on the work that had been performed in ABB China by considering different contingencies and I applied solutions using individual FACTS devices such as FCL, SVC-LightRTM, and HVDC-LightRTM. I analyzed the results from each solution in order to assess its merits and limitations in dealing with fault current and voltage stability problems. Then I presented a novel DC ring topology that provides redundancy, better protection against cascading faults, and does not increase short circuit levels. With this topology, adding loads or power sources does not impact system protection or performance. (2) I proposed two novel designs for a DC circuit breaker that is of critical importance to DC applications using multiple converter stations. The proposed designs solve the problem of DC fault clearing without causing significant voltage drops, current oscillations, or shutting down of any converter station connected to the DC bus. The DC breaker rated at a voltage of 320 kV and a current of 3000 A can interrupt DC currents as high as 70 kA within 800 mus. (3) I proposed a novel placement of the DC circuit breakers within the DC ring topology combined with an intelligent protection algorithm that optimizes fault detection and isolation without affecting the rest of the DC system. The protection scheme uses local measurements and special coordination techniques for clearing solid faults and uses differential measurements to identify and isolate high impedance faults.

Haj-Maharsi, Mohamed Yassine

2009-07-01

143

STEP-UP VERSUS STEP-DOWN DC/DC CONVERTERS FOR RF-POWERED SYSTEMS Sean Nicolson and Khoman Phang  

E-print Network

STEP-UP VERSUS STEP-DOWN DC/DC CONVERTERS FOR RF-POWERED SYSTEMS Sean Nicolson and Khoman Phang a design that uses a step- down converter. We analyze which system can operate from a lower input source step-down designs. We demonstrate that the step-down architecture can increase maximum operable link

Phang, Khoman

144

Research study on multi-KW-DC distribution system  

NASA Technical Reports Server (NTRS)

A detailed definition of the HVDC test facility and the equipment required to implement the test program are provided. The basic elements of the test facility are illustrated, and consist of: the power source, conventional and digital supervision and control equipment, power distribution harness and simulated loads. The regulated dc power supplies provide steady-state power up to 36 KW at 120 VDC. Power for simulated line faults will be obtained from two banks of 90 ampere-hour lead-acid batteries. The relative merits of conventional and multiplexed power control will be demonstrated by the Supervision and Monitor Unit (SMU) and the Automatically Controlled Electrical Systems (ACES) hardware. The distribution harness is supported by a metal duct which is bonded to all component structures and functions as the system ground plane. The load banks contain passive resistance and reactance loads, solid state power controllers and active pulse width modulated loads. The HVDC test facility is designed to simulate a power distribution system for large aerospace vehicles.

Berkery, E. A.; Krausz, A.

1975-01-01

145

Parallel Wire Driven System for Joint Torque Estimation of Human Leg in Passive Motion  

NASA Astrophysics Data System (ADS)

This paper presents a leg torque estimation system for a passive motion that uses an incompletely restrained parallel wire driven mechanism. After comparing completely and incompletely restrained parallel wire driven systems, we organize the characteristics of both systems for human torque estimation. Defining the work spaces of four kinds for the incompletely restrained mechanism, we analyze the realization of passive tracking for a leg. Then we demonstrate that the walking motion can be achieved using low-power actuators. A case example of design is introduced to manufacture a prototype for the leg torque estimation. Finally, the result of the leg torque estimation is presented through experiments conducted using a prototype system.

Kino, Hitoshi; Saisho, Kenichi; Miyazoe, Tsutomu; Kawamura, Sadao

146

Development of five-degree-of-freedom wire suspension power-assisted system using linear cylinders  

Microsoft Academic Search

In this paper, a power-assisted attitude control system consisting of parallel wires is proposed. This system controls the attitude of an object, thus reducing the burden on the operator and allowing direct manipulation. In our previous research, a power-assisted control system for an overhead crane was proposed. Operators could move a heavy object freely in horizontal and vertical directions and

Takanori Miyoshi; Kenji Suzuki; Kazuhiko Terashima

2011-01-01

147

DC Cool  

NSDL National Science Digital Library

When Forbes Magazine ranked Washington DC the coolest city in America back in August, the web exploded with commentary. A typical tweet: â??What makes DC Americaâ??s coolest city? The soul crushing architecture that lines our streets or the hordes of zombies that walk them?â? News outlets form the Wire to the Los Angeles Times balked. Even the Washington Post questioned the ranking. Still, DC has a lot to offer. And this hip little site, sponsored by the city, wants to tell you all about it. The Scene features links to Eat + Drink, See + Do, and other categories. Click any photo for a short vignette. For instance, a smiling panda links you to an interview with Nicole MacCorkle, the giant panda keeper at Smithsonianâ??s National Zoo.

148

Electrical endurance of Co/Ni wire for magnetic domain wall motion device  

NASA Astrophysics Data System (ADS)

We investigated electrical endurance of perpendicularly magnetized Co/Ni wires, which are a promising candidate material system for current-induced domain wall motion device. Monitoring the wire resistance while applying dc stress is shown to be a promising way to evaluate the electrical breakdown. An electromigration model describes well the observed time-to-failure as a function of temperature and current density. The dc stress current density which leads to 10-yr lifetime with 50% failure at 150 °C was twice as large as the threshold current density for domain wall motion, suggesting that the device with Co/Ni wire is highly durable against electrical stresses.

Fukami, S.; Yamanouchi, M.; Honjo, H.; Kinoshita, K.; Tokutome, K.; Miura, S.; Ikeda, S.; Kasai, N.; Ohno, H.

2013-06-01

149

R-Matrix Theory of Quantum Wire Systems  

NASA Astrophysics Data System (ADS)

In molecular wires the line between device and molecule becomes blurred. Scattering theory in general has been very useful to model the I-V characteristics of small devices and one approach, R-matrix theory, seems uniquely well suited. R-matrix theory allows one to quickly calculate the scattering amplitudes from a target region at any energy without having to repeatedly solve the Schrodinger equation in target region at every energy.^1,2 However previous approaches are limited in that they only dealt with two terminal devices, they do not take advantage of modern formulations of R-matrix theory, they ignore excitations of the interior states of the target/device, and they only allow for one electron to be output for every electron input. We develop a formalism that overcomes these deficiencies, and apply it to a simple T-junction device. We discuss the applications of the model to study electroluminescence and novel effects in quantum wires. This material is based on work supported by the National Science Foundation under Grant Nos. EPS-0132534, PHY-0071031, and NSF-MRSEC DMR-0080054. A. M. Lane and R. G. Thomas, Rev. Mod. Phys. 30, 257 (1958). U. Wulf et al., Phys. Rev. B58, 16209 (1998).

Jayasekera, Thushari; Morrison, Michael; Mullen, Kieran

2003-03-01

150

Microprocessor-Controlled DC Motor for Load-Insensitive Position Servo System  

Microsoft Academic Search

The conventional proportional P controller has been often used as the position controller of the dc servo motor. When the unknown and inaccessible load torque, such as the coulomb friction, the gravity, and so on, is imposed on the dc servo motor, this control system has the steady-and\\/or transient-state error.

Kiyoshi Ohishi; Masato Nakao; Kouhei Ohnishi; Kunio Miyachi

1987-01-01

151

A frequency domain model for AC\\/DC\\/AC conversion systems  

Microsoft Academic Search

A simple model in the frequency domain of AC\\/DC\\/AC conversion systems is presented and applied to predict DC and AC current harmonics and interharmonics. It is based on the modulation function theory, but differently from the classical approaches, it allows prediction in a fast and direct way those current interharmonics which are caused by the time variation of the actual

R. Carbone; A. Lo Schiavo; P. Marino; A. Testa

1999-01-01

152

Evaluation of EK System by DC and AC on Removal of Nitrate Complex  

Microsoft Academic Search

DC (Direct current) is used in electrokinetic (EK) technology to extract hazardous materials from soils. Besides, AC (alternating current) electric field is also used to induce particle and fluid motion in electrokinetics. The influence of AC and DC on electrokinetic phenomena was studied for the removal of nitrate complex in soil environment. The experiments were performed by employing three systems

Tae-Hyun Ha; Jeong-Hee Choi; Sundaram Maruthamuthu; Hyun-Goo Lee; Jeong-Hyo Bae

2009-01-01

153

Electrical Interference from Thyristor-Controlled DC Propulsion System of a Transit Car  

Microsoft Academic Search

Analysis and measurement of radiated and conducted electromagnetic interferences were performed on a transit car equipped with chopper-controlled dc propulsion system. The measured values of the radiated interference showed significant disagreement with the calculated values. It was determined from the analysis of the measured data that the voltage drop caused by the dc propulsion-current harmonics contributed to the discrepancies. Extensive

Pritindra Chowdhuri; Dennis F. Williamson

1977-01-01

154

Interface phonon-polaritons in quantum well wire systems of polar ternary mixed crystals  

NASA Astrophysics Data System (ADS)

The interface phonon-polaritons in quasi-one-dimensional rectangular quantum well wire systems consisting of polar ternary mixed crystals have been investigated with the modified random-element-isodisplacement model and the Born-Huang approximation, combined the Maxwell’s equations and the boundary condition of electromagnetic field. The numerical results of the frequencies of interface phonon-polaritons as functions of the wave-vector, geometric structures, as well as composition x for the quantum well wire systems GaAs/AlxGa1-xAs and ZnxCd1-xSe/ZnSe are gained and discussed. It is shown that there are six branches of interface phonon-polariton modes in quantum well wire systems. The effects of “one mode” and “two mode” behaviors of the ternary mixed crystals on the interface modes are also shown in the dispersion curves.

Yan, C. L.; Bao, J.

2014-10-01

155

Implementation and control of grid connected AC-DC-AC power converter for variable speed wind energy conversion system  

Microsoft Academic Search

30 kW electrical power conversion system is developed for a variable speed wind turbine system. In the wind energy conversion system (WECS) a synchronous generator converts the mechanical energy into electrical energy. As the voltage and frequency of generator output vary along the wind speed change, a DC-DC boosting chopper is utilized to maintain constant DC link voltage. The input

Seung-Ho Song; Shin-il Kang; Nyeon-kun Hahm

2003-01-01

156

An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic System with Battery Energy Storage  

PubMed Central

This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods. PMID:24883374

Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M. A.

2014-01-01

157

An optimal control strategy for DC bus voltage regulation in photovoltaic system with battery energy storage.  

PubMed

This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods. PMID:24883374

Daud, Muhamad Zalani; Mohamed, Azah; Hannan, M A

2014-01-01

158

Comparison of three phase current source inverters and voltage source inverters linked with DC to DC boost converters for fuel cell generation systems  

Microsoft Academic Search

Three phase current source inverters (CSI) and voltage source inverters linked with a DC to DC boost converter (VSI+BC) are appropriate solutions to convert electrical energy for distributed fuel cell generation systems. The performance of CSI's and VSI+BC's in this application is shown and both topologies are compared to each other concerning their power semiconductor design rating and their semiconductor

M. Mohr; F. W. Fuchs

2005-01-01

159

The DC-SQUID-based Magnetocardiographic Systems for Clinical Use  

NASA Astrophysics Data System (ADS)

The new line of dc-SQUID-based magnetocardiographic (MCG) systems (named as the "MAG-SCAN"-family) is designed, fabricated and tested. These systems are intended for routine MCG investigations of patients at conditions of real clinical electrophysiological labs. The "MAG-SCAN"-family includes the line of MCG devices compatible in terms of hardware and software with number of measuring channels from 1 to 36. Experimental prototypes of 7- and 9-channel MCG-systems (the models "MAG-SCAN-07" and "MAG-SCAN-09" fabricated at CRYOTON Co. Ltd.) were installed in a few hospitals of Moscow city and operated in an unshielded environment of usual clinical labs. Well balanced second-order gradiometers have been used for MCG data recording. They demonstrated an intrinsic noise level better than 5 fT/?Hz. The total noise level of about 20-40 fT/?Hz was measured at urban conditions of Moscow city. The package of special software (named as the "SOFTMAG") was developed as two autonomous subsystems that allow the preprocessing of the heart magnetic signals and the spatio-temporal analysis of the field characteristics and the field sources. The software employs the algorithms for the analysis and estimation of the spatio-temporal characteristics of the heart magnetic field and the correspondent electrical currents distributions. More than 2000 investigations of different volunteers including healthy persons, patients with high blood-pressure, ischemic disease (IHD), chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA) were carried out and sets of MCG-parameters specific for each group were found.

Maslennikov, Yu. V.; Primin, M. A.; Slobodchikov, V. Yu.; Khanin, V. V.; Nedayvoda, I. V.; Krymov, V. A.; Okunev, A. V.; Moiseenko, E. A.; Beljaev, A. V.; Rybkin, V. S.; Tolcheev, A. V.; Gapelyuk, A. V.

160

Research on CAD\\/CAPP integrated system for automobile wiring harness  

Microsoft Academic Search

In order to improve the efficiency of process planning, a CAD\\/CAPP integrated system for automobile wiring harness was researched. Firstly, its function model was proposed and every module was stated in detail. Secondly, the key technologies of system development were studied, which include graphic database design, the method of inputting product data and the principle of process planning. On the

Jingkui Ruan; Xueliang Zhou

2011-01-01

161

Three-dimensional wire-mesh capacitor system measures fluid density  

NASA Technical Reports Server (NTRS)

Gaging system automatically measures the bulk density of a stored, electrically nonconductive fluid containing varying portions of liquid and vapor. The system employs a three-dimensional wire-mesh capacitor whose capacitance varies with the bulk density of the fluid dielectric medium between the capacitor plates.

1965-01-01

162

Control of steering-by-wire system using bilateral control scheme with passivity approach  

Microsoft Academic Search

Steer-by-wire system, in which the conventional mechanical linkages between the steering wheel and the front wheel are removed, is suited to active steering control, improving vehicle stability, dynamics and maneuverability, and besides, is applied to autonomous steering control to assist the driver. Conventional controller for SBW system is designed by general feedback control method. However, driver can not exactly feel

Jae-Sung Im; Fuminori Ozaki; Nobutomo Matsunaga; Shigeyasu Kawaji

2007-01-01

163

An on-line pulse trains analysis system of the wire-EDM process  

Microsoft Academic Search

Ignition delay time (Td) has been widely used to distinguish the abnormal discharges from the normal ones in wire electrical discharge machining (WEDM) process. In this paper an on-line analysis system for the causality of the Td data sequences was developed to evaluate the machining performance of WEDM process. The system is composed of a stand-alone Td processing circuitry and

Y. S. Liao; M. P. Cheng; K. W. Liao

2009-01-01

164

Design and Analysis of the Main AC/DC Converter System for ITER  

NASA Astrophysics Data System (ADS)

A design of the main AC/DC converter system for ITER is described and the configuration of the main AC/DC converters is presented. To reduce the reactive power absorbed from the converter units, the main AC/DC converters are designed to be series-connected and work in a sequential mode. The structure of the regulator of the converter system is described. A simulation model was built up for the PSCAD/EMTDC code, and the design was validated accordingly. Harmonic analysis and reactive power calculation of the converters units are presented. The results reveal the advantage of sequential control in reducing reactive power and harmonics.

Sheng, Zhicai; Xu, Liuwei; Fu, Peng

2012-04-01

165

Modeling, control, and validation of an electro-hydraulic steer-by-wire system for articulated vehicle applications  

Microsoft Academic Search

X-by-wire control systems in automotive applications refer to systems where the input device used by the operator is connected to the actuation power subsystem by electrical wires, as opposed to being connected by mechanical or hydraulic means. The \\

Salem Haggag; David Alstrom; Sabri Cetinkunt; Alex Egelja

2005-01-01

166

Model Aerodynamic Tests with a Wire-driven Parallel Suspension System in Low-speed Wind Tunnel  

Microsoft Academic Search

Owing to the advantages of wire-driven parallel manipulator, a new wire-driven parallel suspension system for airplane model in low-speed wind tunnel is constructed, and the methods to measure and calculate the aerodynamic parameters of the airplane model are studied. In detail, a static model of the wire-driven parallel suspension is analyzed, a mathematical model for describing the aerodynamic loads exerted

Xiao Yangwen; Lin Qi; Zheng Yaqing; Liang Bin

2010-01-01

167

Low speed control of a DC motor driving a mechanical system with fuzzy adaptive compensation  

E-print Network

A fuzzy adaptive feedforward control scheme in conjunction with classical feedback control is proposed for the low speed control of DC motors driving mechanical systems in the presence of friction. In the fuzzy adaptive scheme, a fuzzy logic based...

Hyun, Dongyoon

1997-01-01

168

Testing of a flat conductor cable baseboard system for residential and commercial wiring  

NASA Technical Reports Server (NTRS)

The results of extensive testing (mechanical, electrical, chemical, environmental, thermal, and analytical) are reported for a flat conductor cable baseboard system for residential and commercial wiring. In all of the tests, Underwriters Laboratories (UL) Standards, UL Tentative Test Programs, or Accepted Engineering Practices were followed during test selection, test setup, and test accomplishment.

Hankins, J. D.

1974-01-01

169

Monitoring Battery System for Electric Vehicle, Based On "One Wire" Technology  

E-print Network

Monitoring Battery System for Electric Vehicle, Based On "One Wire" Technology Javier Ibáñez Vial Department of Electrical Engineering Pontificia Universidad Católica de Chile Santiago, Chile jibanezv@puc.cl Juan W. Dixon, Ph.D. Department of Electrical Engineering Pontificia Universidad Católica de Chile

Catholic University of Chile (Universidad Católica de Chile)

170

An adaptive neuro-fuzzy inference system (ANFIS) model for wire-EDM  

Microsoft Academic Search

A wire electrical discharge machined (WEDM) surface is characterized by its roughness and metallographic properties. Surface roughness and white layer thickness (WLT) are the main indicators of quality of a component for WEDM. In this paper an adaptive neuro-fuzzy inference system (ANFIS) model has been developed for the prediction of the white layer thickness (WLT) and the average surface roughness

Ulas Çaydas; Ahmet Hasçalik; Sami Ekici

2009-01-01

171

DC drive system for cine/pulse cameras  

NASA Technical Reports Server (NTRS)

Camera-drive functions are separated mechanically into two groups which are driven by two separate dc brushless motors. First motor, a 90 deg stepper, drives rotating shutter; second electronically commutated motor drives claw and film transport. Shutter is made of one piece but has two openings for slow and fast exposures.

Gerlach, R. H.; Sharpsteen, J. T.; Solheim, C. D.; Stoap, L. J.

1977-01-01

172

Set Up and Test Results for a Vibrating Wire System for Quadrupole Fiducialization  

SciTech Connect

Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of a quadrupole. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing it. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). The following break up of error was suggested for the fiducialization steps: 10{micro}m for step 1 (finding the center), 20{micro}m for step 2 (finding the wire), and 10{micro}m for step 3 (tooling ball measurements). The purpose of this study is to investigate whether the vibrating wire system meets the requirements for LCLS. In particular, if it can reliably fiducialize a quadrupole magnetic center to within 25{micro}m in both vertical and horizontal directions. The behavior of individual system components is compared to the expected performance. A vibrating wire system was constructed to fiducialize the quadrupoles between undulator segments in the LCLS. This note studies the ability of the system to fulfill the fiducialization requirements.

Not Available

2010-11-29

173

Set Up and Test Results for a Vibrating Wire System for Quadrupole Fiducialization  

SciTech Connect

Quadrupoles will be placed between the undulator segments in LCLS to keep the electron beam focused as it passes through. The quadrupoles will be assembled with their respective undulator segments prior to being placed into the tunnel. Beam alignment will be used to center the quadrupoles, along with the corresponding undulators, on the beam. If there is any displacement between the undulator and the quadrupole axes in the assemblies, the beam will deviate from the undulator axis. If it deviates by more than 80{micro}m in vertical or 140{micro}m in horizontal directions, the undulator will not perform as required by LCLS. This error is divided between three sources: undulator axis fiducialization, quadrupole magnetic axis fiducialization, and assembly of the two parts. In particular, it was calculated that the quadrupole needs to be fiducialized to within 25{micro}m in both vertical and horizontal directions. A previous study suggested using a vibrating wire system for finding the magnetic axis of a quadrupole. The study showed that the method has high sensitivity (up to 1{micro}m) and laid out guidelines for constructing it. There are 3 steps in fiducializing the quadrupole with the vibrating wire system. They are positioning the wire at the magnet center (step 1), finding the wire with position detectors (step 2), and finding the quadrupole tooling ball positions relative to the position detector tooling balls (step 3). The following break up of error was suggested for the fiducialization steps: 10{micro}m for step 1 (finding the center), 20{micro}m for step 2 (finding the wire), and 10{micro}m for step 3 (tooling ball measurements). The purpose of this study is to investigate whether the vibrating wire system meets the requirements for LCLS. In particular, if it can reliably fiducialize a quadrupole magnetic center to within 25{micro}m in both vertical and horizontal directions. The behavior of individual system components is compared to the expected performance. A vibrating wire system was constructed to fiducialize the quadrupoles between undulator segments in the LCLS. This note studies the ability of the system to fulfill the fiducialization requirements.

Levashov, Michael Y.

2010-12-01

174

Force-Feedback System Design for the Steer-By-Wire: Optimisation and Performance Evaluation  

Microsoft Academic Search

Current state of art power assisted steering systems used in vehicles are hydro-mechanical type systems, i.e. the steering column motion is transmitted and amplified by the main hydraulic circuit by hydro-mechanical means. Electrical versions of such steering systems are gaining success and are beginning to be implanted in most vehicles. Next step is the so-called by-wire concept. This paper presents

David Gualino; I.-J. Adounkpe

2006-01-01

175

Operation and force analysis of the guide wire in a minimally invasive vascular interventional surgery robot system  

NASA Astrophysics Data System (ADS)

To develop a robot system for minimally invasive surgery is significant, however the existing minimally invasive surgery robots are not applicable in practical operations, due to their limited functioning and weaker perception. A novel wire feeder is proposed for minimally invasive vascular interventional surgery. It is used for assisting surgeons in delivering a guide wire, balloon and stenting into a specific lesion location. By contrasting those existing wire feeders, the motion methods for delivering and rotating the guide wire in blood vessel are described, and their mechanical realization is presented. A new resistant force detecting method is given in details. The change of the resistance force can help the operator feel the block or embolism existing in front of the guide wire. The driving torque for rotating the guide wire is developed at different positions. Using the CT reconstruction image and extracted vessel paths, the path equation of the blood vessel is obtained. Combining the shapes of the guide wire outside the blood vessel, the whole bending equation of the guide wire is obtained. That is a risk criterion in the delivering process. This process can make operations safer and man-machine interaction more reliable. A novel surgery robot for feeding guide wire is designed, and a risk criterion for the system is given.

Yang, Xue; Wang, Hongbo; Sun, Li; Yu, Hongnian

2015-01-01

176

Operation and force analysis of the guide wire in a minimally invasive vascular interventional surgery robot system  

NASA Astrophysics Data System (ADS)

To develop a robot system for minimally invasive surgery is significant, however the existing minimally invasive surgery robots are not applicable in practical operations, due to their limited functioning and weaker perception. A novel wire feeder is proposed for minimally invasive vascular interventional surgery. It is used for assisting surgeons in delivering a guide wire, balloon and stenting into a specific lesion location. By contrasting those existing wire feeders, the motion methods for delivering and rotating the guide wire in blood vessel are described, and their mechanical realization is presented. A new resistant force detecting method is given in details. The change of the resistance force can help the operator feel the block or embolism existing in front of the guide wire. The driving torque for rotating the guide wire is developed at different positions. Using the CT reconstruction image and extracted vessel paths, the path equation of the blood vessel is obtained. Combining the shapes of the guide wire outside the blood vessel, the whole bending equation of the guide wire is obtained. That is a risk criterion in the delivering process. This process can make operations safer and man-machine interaction more reliable. A novel surgery robot for feeding guide wire is designed, and a risk criterion for the system is given.

Yang, Xue; Wang, Hongbo; Sun, Li; Yu, Hongnian

2015-03-01

177

Coordinating the dc power injections of a multiterminal HVDC system for dynamic control of AC line flows  

SciTech Connect

As more dc terminals, in the form of links or multiterminal systems, come into operation, the opportunity for controlling ac line flows using the injected dc powers increases. This paper describes a study undertaken to determine the feasibility of using an on-line method to coordinate the dc injections of a multiterminal dc system to dynamically control the power flows in certain ac lines of an integrated ac-dc power system. The proposed controller can be used to steer and to regulate the power flows, and also to damp the power oscillations in these ac lines. The effectiveness of the controller is demonstrated using a transient simulation program.

Hamzei-Nejad, A.; Ong, C.M.

1986-05-01

178

An integrated dc-dc power converter for use in distributed generation power systems  

Microsoft Academic Search

Distributed generation (DG) power systems are becoming increasingly attractive as alternatives to traditional centralized power systems. Fuel cells are an important resource that can be used in such systems, but power electronic converter interfaces are needed to ensure that fuel cells can provide fixed and regulated output voltages as the output of a fuel cell can vary with load. Given

Pritam Das; Gerry Moschopoulos

2008-01-01

179

Modeling of overhead transmission lines with segmented shield wires for signal attenuation calculation in power line carrier systems  

Microsoft Academic Search

This paper presents modeling methods for overhead transmission lines with segmented shield wires, as well as signal attenuation calculation for different coupling methods for use in power line carrier (PLC) systems. The purpose of this paper is to present a generalized method to model transmission lines with segmented shield wires, along with steps for signal attenuation calculation in the phase

Shanshan Yang; Gregory A. Franklin

2011-01-01

180

Radio frequency dc-dc power conversion  

E-print Network

THIS THESIS addresses the development of system architectures and circuit topologies for dc-dc power conversion at very high frequencies. The systems architectures that are developed are structured to overcome limitations ...

Rivas, Juan, 1976-

2007-01-01

181

Reversible AC Drive Systems Based on Parallel AC-AC DC-Link Converters  

Microsoft Academic Search

In this paper, two reversible single-phase to three-phase ac drive systems are proposed. They are composed of a single induction motor fed by two parallel single- phase to three-phase dc-link converters without isolation transformers. For sake of generalization a configuration composed of three parallel single-phase to three-phase dc-link converters is also discussed. The proposed topologies permit to reduce the current

C. B. Jacobina; E. C. dos Santos; B. de S. Gouveia; E. da Silva

2008-01-01

182

Stability of large DC power systems using switching converters, with application to the International Space Station  

Microsoft Academic Search

A stability approach has been developed for the International Space Station PV power system, which is applicable to any large DC power system. It is based on establishing a set of phase and gain requirements at key subsystem interface points throughout the power system, which provide good confidence that the system will be stable under small signal conditions, with reasonable

E. W. Gholdston; K. Karimi; F. C. Lee; J. Rajagopalan; Y. Panov; B. Manners

1996-01-01

183

Web-Based Agent System for Interworking Between Wired Network Devices and Mobile Devices  

Microsoft Academic Search

A web-based agent system has been proposed and demonstrated to realize the interworking services between wired network devices\\u000a and mobile devices. The agent system enables the resource-limited mobile device to support Jini network services without any\\u000a additional client program installation in it. It also provides the list of services available on the network in real time,\\u000a which facilitates the users

Sang Tae Kim; Hyun Deok Kim

2006-01-01

184

DC-DC converters for electric vehicle applications  

Microsoft Academic Search

An integral part of any modern day electric vehicle is power electronic circuits (PECs) comprising of DC-AC inverters and DC-DC converters. A DC-AC inverter supplies the high power electric motor and utility loads such as air-conditioning system, whereas a DC-DC converter supplies conventional low-power, low-voltage loads. However, the need for high power bidirectional DC- DC converters in future electric vehicles

Dakshina M. Bellur; Marian K. Kazimierczuk

2007-01-01

185

Comparison of solar hydrogen storage systems with and without power-electronic DC–DC-converters  

Microsoft Academic Search

For long-time-storage problems of electrical energy, hydrogen-storage-systems have some significant advantages. In photovoltaic systems, especially in island-applications, they can help to solve the seasonal storage problem with solar energy and a not correlated energy demand. In summer the surplus of photovoltaic energy is used to produce hydrogen-gas by water electrolysis. In winter the hydrogen is converted back to electricity with

H Solmecke; O Just; D Hackstein

2000-01-01

186

Modeling, analysis and design for hybrid power systems with dual-input DC\\/DC converter  

Microsoft Academic Search

Hybrid power systems derive power simultaneously from several renewable energy sources and deliver power continuously to the load. For such systems, the use of a multiple-input converter (MIC) has the advantage of simpler circuit design and lower cost, compared to the conventional use of several single-input converters. Taking dual-input Buck converter as the example in this paper, a new power

Yan Li; Xinbo Ruan; Dongsheng Yang; Fuxin Liu

2009-01-01

187

Development of hand-eye system with 3-D vision and microgripper and its application to assembling flexible wires  

Microsoft Academic Search

A hand-eye system with 3-D vision system and a microgripper has been developed for handling, forming and inserting flexible wires in electronic assembles. The hand-eye system performs its task based on visual sensor and force sensor data. The vision system uses a camera, a laser-multiplanar light projector, and a videorate image processor to measure the 3-D geometry of flexible wires

T. Maruyama; S. Kanda; M. Sato; T. Uchiyama

1989-01-01

188

Multiple-Module High-Gain High-Voltage DC–DC Transformers for Offshore Wind Energy Systems  

Microsoft Academic Search

Renewable energy sources, such as offshore wind farms, require high voltage gains in order to interface with power transmission networks. These conversions are normally made us- ing bulky, complex, and costly transformers and high-voltage ac- dc converters with unnecessary bidirectional power flow capability. Multiple modules of single-switch single-inductor dc- dc converters can reach high gains without transformers in these applications

Nicholas Denniston; Ahmed M. Massoud; Shehab Ahmed; Prasad N. Enjeti

2011-01-01

189

A DC-DC Converter-Based PEM Fuel Cell System Emulator  

E-print Network

. In contrast to classical electricity generation system, such as heat engines, the theoretical electrical). If hydrogen is produced from clean energy sources, this makes fuel cells an attractive and clean alternative reactor where hydrogen (or reformed gas) and oxygen (or air) are fed at the inlet of the fuel cell stack

Boyer, Edmond

190

Cable Bundle Wire Derating  

NASA Technical Reports Server (NTRS)

The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: 3.7 amps per wire, bundle of 15 or more wires, 70 C environment, and vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

Lundquist, Ray A.; Leidecker, Henning

1998-01-01

191

Cable Bundle Wire Derating  

NASA Technical Reports Server (NTRS)

The allowable operating currents of electrical wiring when used in the space vacuum environment is predominantly determined by the maximum operating temperature of the wire insulation. For Kapton insulated wire this value is 200 C. Guidelines provided in the Goddard Space Flight Center (GSFC) Preferred Parts List (PPL) limit the operating current of wire within vacuum to ensure the maximum insulation temperature is not exceeded. For 20 AWG wire, these operating parameters are: (1) 3.7 amps per wire; (2) bundle of 15 or more wires; (3) 70 C environment: and (4) vacuum of 10(exp -5) torr or less. To determine the behavior and temperature of electrical wire at different operating conditions, a thermal vacuum test was performed on a representative electrical harness of the Hubble Space Telescope (HST) power distribution system. This paper describes the test and the results.

Lundquist, Ray A.; Leidecker, Henning

1998-01-01

192

Comparison of Two Autonomous AC-DC Converters for Piezoelectric Energy Scavenging Systems  

E-print Network

- 1 - Comparison of Two Autonomous AC-DC Converters for Piezoelectric Energy Scavenging Systems E Cornaredo, Milan, Italy Abstract - Piezoelectric Energy Scavenging Systems (PESS) are used to convert scavenging systems are used to harvest the normally lost environmental energy (associated to vibrations

Boyer, Edmond

193

The optimal control of a constrained drive system with brushless DC motor  

Microsoft Academic Search

The optimal (according to the quadratic performance index) control method of a drive position system with an electronically commutated brushless DC motor is discussed. Initially developed for linear, unconstrained, and undistributed systems, this optimal control method is now applied to a system having constrained state and input variables (e.g. armature voltage, armature current, rotor speed) and unknown disturbances (e.g. load

P. M. Pelczewski; ULRICH H. KUNZ

1990-01-01

194

Nonlinear control for AC\\/DC power system with nonlinear loads  

Microsoft Academic Search

In view of the nonlinearity of loads and HVDC in power systems, the M derivative, M bracket and MIMO feedback linearization based on nonlinear differential algebraic system (NDAS) are introduced into the design of nonlinear controller for parallel AC\\/DC power system. Bronovsky normal form for NDAS is derived when the M relative degree of NDAS is less than its dimension

G. H. Xu; C. Chen; J. Wang; D. D. Li

2004-01-01

195

AC Versus DC Distribution SystemsDid We Get it Right?  

Microsoft Academic Search

We presently enjoy a predominantly AC electrical distribution system, the engineering basis for which was designed over 100 years ago. While AC distribution systems have served us well, we should periodically pause to assess what opportunities we have accepted or been denied by the overwhelming predominance of AC electrical power distribution systems. What opportunities could be obtained by engineering DC

Donald J. Hammerstrom

2007-01-01

196

System Security Authorization Agreement (SSAA) for the WIRE Archive and Research Facility  

NASA Technical Reports Server (NTRS)

The Wide-Field Infrared Explorer (WIRE) Archive and Research Facility (WARF) is operated and maintained by the Department of Physics, USAF Academy. The lab is located in Fairchild Hall, 2354 Fairchild Dr., Suite 2A103, USAF Academy, CO 80840. The WARF will be used for research and education in support of the NASA Wide Field Infrared Explorer (WIRE) satellite, and for related high-precision photometry missions and activities. The WARF will also contain the WIRE preliminary and final archives prior to their delivery to the National Space Science Data Center (NSSDC). The WARF consists of a suite of equipment purchased under several NASA grants in support of WIRE research. The core system consists of a Red Hat Linux workstation with twin 933 MHz PIII processors, 1 GB of RAM, 133 GB of hard disk space, and DAT and DLT tape drives. The WARF is also supported by several additional networked Linux workstations. Only one of these (an older 450 Mhz PIII computer running Red Hat Linux) is currently running, but the addition of several more is expected over the next year. In addition, a printer will soon be added. The WARF will serve as the primary research facility for the analysis and archiving of data from the WIRE satellite, together with limited quantities of other high-precision astronomical photometry data from both ground- and space-based facilities. However, the archive to be created here will not be the final archive; rather, the archive will be duplicated at the NSSDC and public access to the data will generally take place through that site.

2002-01-01

197

Modeling of Steer-by-Wire System Used in New Braking Handwheel Concept  

NASA Astrophysics Data System (ADS)

The handwheel is one of the primary control mechanisms of automobile thus interaction between the handwheel and the driver is critical to safety. The driver applies forces that direct the vehicle while the handwheel communicates feedback information to the driver of the forces experience by the car within its environment. The handwheel also provides a predictable mechanical feel to the driver to allow smooth and safe control. Many researchers tried to reproduce this feeling by creating steer-by-wire systems. This paper explores this new concept of handwheel and it describes the modeling steps of the components including the restitution mechanism for force feedback and its various links with the vehicle lateral dynamics and the pneumatic contacts. The aim is to explore the possibility to combine a braking device within the steer-by-wire system in order to provide a more suitable and ergonomic device to the driver.

Messaoudène, K.; Oufroukh, N. Ait; Mammar, S.

2008-06-01

198

Development of a uninterrupted power system: ac and dc to dc converter  

NASA Technical Reports Server (NTRS)

This program covered the design, fabrication and testing of an advanced development model uninterrupted power system. The input and output requirements imposed on the power processor were specified such that the unit is electrically interchangeable with existing power systems used by the Federal Aviation Administration in installations which have a history of failure due to electrical transient conditions. Input power is from either of two single-phase ac power sources or batteries with electronic selection and transfer between power sources. Battery reconditioning is automatic when either ac source is present. The output power is rated at 84OW; the nominal output is 24V at 35A. Within the 84OW limit, the regulated output voltage is adjustable from 22V to 30Vdc. Protection against continuous overloading or short circuit is provided. The unit is packaged in a standard 19-inch rack mount configuration with 7-inch panel height. Controls are on the front panel with power input and output through connectors on the rear surface. Cooling is by free convection from fin areas located on the side and rear panels. The packaged unit weighs 52.8 lbs., which can be reduced significantly if a three-phase ac power source is used.

Cronin, D. L.; Schoenfeld, A. D.

1973-01-01

199

Steering Chain HIL Simulator for Steer-By-Wire Systems  

Microsoft Academic Search

Advanced control for automotive is one of the most promising research topic in the forthcoming decade. Actually, the long-term target is the substitution of most hydraulic car systems with their electronic counterparts. A bright example is set by the steering function, which has passed from pure mechanical to power assisted and recently to pure electrically power assisted function. The next

Carlo Bernard; Silverio Bolognani; Luca Peretti; Mauro Zigliotto

2006-01-01

200

An Operating and Diagnostic Knowledge-Based System for Wire EDM  

Microsoft Academic Search

\\u000a The selection of machining parameters and machine settings for wire electrical discharge machining (WEDM) depends mainly on\\u000a both technologies and experience provided by machine tool manufacturers. The present work designs a knowledge-based system\\u000a (KBS) to select the optimal process parameters settings and diagnose the machining conditions for WEDM. Moreover, the present\\u000a results supply users of WEDM with beneficial data avoiding

Samy Ebeid; Raouf Fahmy; Sameh Habib

2003-01-01

201

Reliability of hybrid photovoltaic DC micro-grid systems for emergency shelters and other applications  

NASA Astrophysics Data System (ADS)

Improvement of energy efficiency in the SunSmart Schools Emergency Shelters requires new methods for optimizing the energy consumption within the shelters. One major limitation in current systems is the requirement of converting direct current (DC) power generated from the PV array into alternating current (AC) power which is distributed throughout the shelters. Oftentimes, this AC power is then converted back to DC to run certain appliances throughout the shelters resulting in a significant waste of energy due to DC to AC and then again AC to DC conversion. This paper seeks to extract the maximum value out of PV systems by directly powering essential load components within the shelters that already run on DC power without the use of an inverter and above all to make the system reliable and durable. Furthermore, additional DC applications such as LED lighting, televisions, computers and fans operated with DC brushless motors will be installed as replacements to traditional devices in order to improve efficiency and reduce energy consumption. Cost of energy storage technologies continue to decline as new technologies scale up and new incentives are put in place. This will provide a cost effective way to stabilize the energy generation of a PV system as well as to provide continuous energy during night hours. It is planned to develop a pilot program of an integrated system that can provide uninterrupted DC power to essential base load appliances (heating, cooling, lighting, etc.) at the Florida Solar Energy Center (FSEC) command center for disaster management. PV arrays are proposed to be installed on energy efficient test houses at FSEC as well as at private homes having PV arrays where the owners volunteer to participate in the program. It is also planned to monitor the performance of the PV arrays and functioning of the appliances with the aim to improve their reliability and durability. After a successful demonstration of the hybrid DC microgrid based emergency shelter together with the monitoring system, it is planned to replicate it at other schools in Florida and elsewhere to provide continuous power for essential applications, maximizing the value of PV generation systems.

Dhere, Neelkanth G.; Schleith, Susan

2014-10-01

202

A novel method for simulation of brushless DC motor servo-control system based on MATLAB  

NASA Astrophysics Data System (ADS)

This paper provides a research about the simulation of brush-less DC motor (BLDCM) servo control system. Based on the mathematical model of Brush-less DC motor (BLDCM), built the system simulation model with the MATLAB software. When the system model is made, the isolated functional blocks, such as BLDCM block, the rotor's position detection block, change-phase logic block etc. have been modeled. By the organic combination of these blocks, the model of BLDCM can be established easily. The reasonability and validity have been testified by the simulation results and this novel method offers a new thought way for designing and debugging actual motors.

Tao, Keyan; Yan, Yingmin

2006-11-01

203

Passive Obstacle Detection System (PODS) for Wire Detection  

Microsoft Academic Search

Boeing has developed algorithms and processing to detect power lines and cables in passive imagery from a wide variety of different sources. The algorithm has been demonstrated with imagery from visible, medium and long wave infra-red (MWIR and LWIR), and Passive MilliMeter Wave (PMMW) sensors. Flight demonstrations of the real-time system have been performed with both visible and LWIR image

John N. Sanders-Reed; Dennis J. Yelton; Christian C. Witt; Ralph R. Galetti

204

Passive obstacle detection system (PODS) for wire detection  

Microsoft Academic Search

Boeing has developed algorithms and processing to detect power lines and cables in passive imagery from a wide variety of different sources. The algorithm has been demonstrated with imagery from visible, medium and long wave infra-red (MWIR and LWIR), and Passive MilliMeter Wave (PMMW) sensors. Flight demonstrations of the real-time system have been performed with both visible and LWIR image

John N. Sanders-Reed; Dennis J. Yelton; Christian C. Witt; Ralph R. Galetti

2009-01-01

205

Strain behavior of quantum wires and quantum boxes in III-V material systems  

NASA Astrophysics Data System (ADS)

Directly etched and regrown quantum wires and quantum boxes have been fabricated, characterized, and modeled in order to study the behavior of non-uniform strain in quantum heterostructures in III-V material systems. Photoluminescence data show a dramatic decrease in peak intensity as quantum wire or box width decreases, while the energy at which peak emission occurs and the width of the emission peak both increase with decreasing feature width. It is shown that strain is primarily responsible for these three effects, as each quantum heterostructure's growth-direction dilation, caused by horizontal lattice-matching to the substrate and cap layer, is opposed by growth-direction compression from lattice-matching the cladding material on the heterostructure sidewalls. Through photoluminescence data and calculations based on transmission electron microscopy measurements of spatial variation of lattice constant, the peak intensity reduction, peak energy shift, and spectral broadening are quantitatively explained by a combination of non-uniform strain behavior and purely geometric considerations. That these factors suffice to explain the observed intensity reduction also refutes the presence of strain-induced dislocations. A new theoretical analysis of strain behavior in quantum heterostructures is developed, valid for small systems whose discreteness precludes classical continuum treatment. The variation of growth-direction and in-plane lattice constants within a quantum heterostructure and the surrounding cladding is systematically derived, and novel predictions are made; the aspect ratio of the quantum wire or quantum box cross-section is found to be the principal determinant of the qualitative strain behavior. A computer simulation, executing lattice dynamics at the atomic level using the Stillinger-Weber and modified Lennard-Jones potentials, is created and is successfully used to confirm all predictions of the theoretical model. The simulation, able to model any quantum well, quantum wire, or quantum box system in III- V zincblende materials, also adds quantitative predictability to the theoretical analysis and illuminates the experimental photoluminescence and microscopy data.

Tentarelli, Eric S.

206

Detection of High-impedance Arcing Faults in Radial Distribution DC Systems  

NASA Technical Reports Server (NTRS)

High voltage, low current arcing faults in DC power systems have been researched at the NASA Glenn Research Center in order to develop a method for detecting these 'hidden faults', in-situ, before damage to cables and components from localized heating can occur. A simple arc generator was built and high-speed and low-speed monitoring of the voltage and current waveforms, respectively, has shown that these high impedance faults produce a significant increase in high frequency content in the DC bus voltage and low frequency content in the DC system current. Based on these observations, an algorithm was developed using a high-speed data acquisition system that was able to accurately detect high impedance arcing events induced in a single-line system based on the frequency content of the DC bus voltage or the system current. Next, a multi-line, radial distribution system was researched to see if the arc location could be determined through the voltage information when multiple 'detectors' are present in the system. It was shown that a small, passive LC filter was sufficient to reliably isolate the fault to a single line in a multi-line distribution system. Of course, no modification is necessary if only the current information is used to locate the arc. However, data shows that it might be necessary to monitor both the system current and bus voltage to improve the chances of detecting and locating high impedance arcing faults

Gonzalez, Marcelo C.; Button, Robert M.

2003-01-01

207

Wire Weight  

USGS Multimedia Gallery

Wire weight is lowered to water surface to measure stage at a site. Levels are made to the wire weights elevation from known benchmarks to ensure correct readings. This wire weight is located along the Missouri River in Bismarck, ND....

208

Dc-SQUID sensor system for multichannel neuromagnetometry  

SciTech Connect

This paper reports on various DC-SQUID sensor configurations developed for use in the authors' 19-channel neuromagetometer. Apart from the standard type, resistively and indictively shunted SQUIDs were made, allowing for a large screening factor {beta} ({gt}1). In this way signal coupling from the pick-up coil to the SQUID is facilitated and capactive coupling between the input coil and the SQUID washer can be decreased. The number of turns of the input coil is decreased further by allowing for an inductance mismatch in the input circuit. Although theoretically both measures give rise to an increased field noise of the sensor, they may lead to a reduction of the excess noise and the noise balance may become positive.

Houwman, E.P.; Veldhuis, D.; Flokstra, ter Brake, H.J.M.; Jaszczuk, W.; Rogalla, H. (Univ. of Twente, Faculty of Applied Physics, P.O. Box 217, 7500 AE Enschede (NL)); Martinez, A. (Universidad de Zaragoza, E.T.S.I.I. Maria Zambrano 50, 50015 Zaragoza (ES))

1991-03-01

209

NASA/BAE Systems SpaceWire Efforts  

NASA Technical Reports Server (NTRS)

This paper discusses the state of the NASA and BAE SYSTEMS developments using Spacewire. NASA has developed intellectual property that implements Spacewire in Register Transfer Level VHDL for a Spacewire link and router. This design has been extensively verified using directed tests from the Spacewire Standard and design specification, as well as being randomly tested to flush out hard to find bugs in the code. The high level features of the design will be discussed, including the support for multiple time code masters, which will be useful for the James Webb Space Telescope electrical architecture. This design is now ready to be targeted to FPGA's and ASICs. Target utilization and performance information will be presented for some spaceflight qualified FPGA's and a discussion of the ASIC implementations will be addressed. In particular, the BAE SYSTEMS ASIC will be highlighted which will be implemented in their 0.25 micron rad-hard line. The chip will implement a 4-port router with the ability to tie chips together to make larger routers without external glue logic. This part will have integrated LVDS driver/receivers, include a PLL and include skew control logic. It will be targeted to run at greater than 300 MHz and include the implementation for the proposed Spacewire transport layer. The need to provide a reliable transport mechanism for Spacewire has been identified by both NASA and ESA, who are attempting to define a transport layer standard that utilizes a low overhead, low latency connection oriented approach. The Transport layer needs to be implemented in hardware-to prevent bottlenecks.

Rakow, Glenn Parker; Schnurr, Richard G.; Kapcio, Paul

2003-01-01

210

Feasibility study of a 270V dc flat cable aircraft electrical power distributed system  

Microsoft Academic Search

This report documents the efforts of a one man-year feasibility study to evaluate the usage of flat conductors in place of conventional round wires for a 270 volt direct current aircraft power distribution system. This study consisted of designing electrically equivalent power distribution harnesses in flat conductor configurations for a currently operational military aircraft. Harness designs were established for installation

M. J. Musga; R. J. Rinehart

1982-01-01

211

A multistep photothermic-driven drug release system using wire-framed au nanobundles.  

PubMed

Here, wire-framed Au nanobundles (WNBs), which consist of randomly oriented and mutually connected Au wires to form a bundle shape, are synthesized. In contrast to conventional nanoparticles (spheres, rods, cubes, and stars), which exhibit nanostructure only on the surface, cross-sectional view image shows that WNBs have nanostructures in a whole volume. By using this specific property of WNBs, an externally controllable multistep photothermic-driven drug release (PDR) system is demonstrated for in vivo cancer treatment. In contrast to conventional nanoparticles that encapsulate a drug on their surface, WNBs preserve the drug payload in the overall inner volume, providing a drug loading capacity sufficient for cancer therapy. An improved in vivo therapeutic efficacy of PDR therapy is also demonstrated by delivering sufficient amount of drugs to the target tumor region. PMID:25044601

Bang, Doyeon; Lee, Taeksu; Choi, Jihye; Park, Yeonji; Kim, Eunkyoung; Huh, Yong-Min; Haam, Seungjoo

2015-01-01

212

Low-Cost Undergraduate Control Systems Experiments Using Microcontroller-Based Control of a DC Motor  

ERIC Educational Resources Information Center

This paper presents low-cost experiments for a control systems laboratory module that is worth one and a third credits. The experiments are organized around the microcontroller-based control of a permanent magnet dc motor. The experimental setups were built in-house. Except for the operating system, the software used is primarily freeware or free…

Gunasekaran, M.; Potluri, R.

2012-01-01

213

DC Gas-Discharge Systems: (references refer to the list of publications given in chapter 12)  

E-print Network

4. DC Gas-Discharge Systems: Experiment (references refer to the list of publications given-dimensional gas-discharge systems are recorded in the gas space of the device fig. 4.1 most easily via gas-discharge specific modelling is based on a set of drift diffusion equations supplemented

Purwins, Hans-Georg

214

AC and DC output fuel cell hybrid system: Design, building and testing  

Microsoft Academic Search

This paper develops, builds and tests a hybrid system made up of a fuel cell stack and a battery bank. The hybrid system has been built to supply DC and AC outputs. Voltage levels established on electrical interconnection points are achieved with several power conditioning stages controlled by pulse width modulation (PWM) and gain scheduling techniques. This work means a

F. Segura; J. M. Andujar; E. Duran

2009-01-01

215

Evaluating alternatives for integrating distributed DC generation with AC power systems  

Microsoft Academic Search

Distributed generation generally means on site electric power generation devices such as photovoltaics or fuel cells that are installed at the customer end of the electric power system. One complication is that the photovoltaic panel and the fuel cell generate direct current (DC) while the electric power system and thus existing end use equipment has been designed for alternating current

F. Wicks

2000-01-01

216

Evaluation of harmonics and interharmonics produced by AC\\/DC\\/AC conversion systems  

Microsoft Academic Search

A new model of line commutated AC\\/DC\\/AC conversion systems is presented and discussed. It is based on the inclusion of the modulation function approach inside the iterative harmonic and interharmonic analysis algorithm. The new model allows to perform the evaluation of waveform distortion taking into account comprehensive representations of both supplying and load systems and overcoming their convergence problems and

Francesco De Rosa; Roberto Langella; A. Testa

2004-01-01

217

Application of SMES Unit in Improving the Performance of an AC\\/DC Power System  

Microsoft Academic Search

This paper investigates the use of a superconducting magnetic energy storage (SMES) unit to improve the performance of an ac\\/dc power system. In this context, investigations have been conducted on a large turbine-generator unit connected to a high- voltage direct current (HVDC) system. The impact of HVDC con- verter station faults on the torsional torques induced in turbine- generator shafts

A. Abu-Siada; Syed Islam

2011-01-01

218

SpaceWire-based thermal-infrared imager system for asteroid sample return mission HAYABUSA2  

NASA Astrophysics Data System (ADS)

A thermal-infrared (TIR) imager system is developed for HAYABUSA2, which is planned to be launched in 2014 and aims at sample-return from a C-class near-Earth asteroid 162173 (1999JU3) considered to contain organic or hydrated materials. The system consists of a TIR imager and digital electronics, which are used not only for the scientific investigation of physical properties of the asteroid surface, but also for the assessment of landing site selection and safe descent operation onto the asteroid surface with in situ measurement. TIR adopts an uncooled bolometer. Image operations such as multiple images summation, dark image subtraction, and the compensation of dead pixels are processed onboard. A processing module is connected to sensor interfaces through SpaceWire in order to provide deterministic processing time. Data compression is also provided to reduce the restriction of transmission time, which provides the equivalent compression ratio as JPEG2000 in 1/30 processing time in average. A high-speed data recorder is connected through SpaceWire in order to record TIR data in parallel with other sensor data. The modularity of SpaceWire enables us to use these as built devices for TIR and inherits the same design as the long-wavelength infrared imager developed for the Venus climate orbiter Akatsuki.

Hihara, Hiroki; Iwase, Kaori; Sano, Junpei; Otake, Hisashi; Okada, Tatsuaki; Funase, Ryu; Kashikawa, Ryoichi; Higashino, Isamu; Masuda, Tetsuya

2014-01-01

219

Wiring of Divergent Networks in the Central Auditory System  

PubMed Central

Divergent axonal projections are found throughout the central auditory system. Here, we evaluate these branched projections in terms of their types, distribution, and putative physiological roles. In general, three patterns of axon collateralization are found: intricate local branching, long-distance collaterals, and branched axons (BAs) involved in feedback-control loops. Local collaterals in the auditory cortex may be involved in local processing and modulation of neuronal firing, while long-range collaterals are optimized for wide-dissemination of information. Rarely do axons branch to both ascending and descending targets. Branched projections to two or more widely separated nuclei or areas are numerically sparse but widespread. Finally, branching to contralateral targets is evident at multiple levels of the auditory pathway and may enhance binaural computations for sound localization. These patterns of axonal branching are comparable to those observed in other modalities. We conclude that the operations served by BAs are area- and nucleus-specific and may complement the divergent unbranched projections of local neuronal populations. PMID:21847372

Lee, Charles C.; Kishan, Amar U.; Winer, Jeffery A.

2011-01-01

220

Design and test experience with a triply redundant digital fly-by-wire control system  

NASA Technical Reports Server (NTRS)

A triplex digital fly-by-wire flight control system was developed and then installed in a NASA F-8C aircraft to provide fail-operative, full authority control. Hardware and software redundancy management techniques were designed to detect and identify failures in the system. Control functions typical of those projected for future actively controlled vehicles were implemented. This paper describes the principal design features of the system, the implementation of computer, sensor, and actuator redundancy management, and the ground test results. An automated test program to verify sensor redundancy management software is also described.

Szalai, K. J.; Felleman, P. G.; Gera, J.; Glover, R. D.

1976-01-01

221

Manufacturing Technology For A High Resolution Real Time Infrared System For Printed Wiring Assemblies Testing  

NASA Astrophysics Data System (ADS)

A system has been developed under contract from the U. S. Air Force for noncontact testing of printed wiring assemblies (PWAs) in depot level environments. The testing is performed by sensing the thermal image of the powered PWA and comparing it to a thermal image from a known good PWA. Designed around a central host computer, the system is completely automatic and quite operator interactive. The complete system integrates a host computer with an Infrared Scanner, a Digital Image Processor, a trackball controller, a TV monitor, a video printer and a fixture for mounting the PWA under test.

Hershman, G.; Galter, I.; Grove, J.; McDonough, D.; Sanders, J.; Pearson, K.; Webster, J.

1985-03-01

222

Broadband slow-wave systems of subwavelength thickness excited by a metal wire  

NASA Astrophysics Data System (ADS)

We propose a broadband slow-wave system based on metallic graded grating structures of subwavelength thickness. A metal wire is used to excite the slow waves propagating along the gratings. The analysis and full-wave simulations show that the electromagnetic waves could be stopped at designed positions under different frequencies. Experiments are conducted in the microwave frequencies to verify the proposed system. The measured results show very good agreements to the full-wave simulations. We have further modeled a broadband slow-wave system of subwavelength thickness in the terahertz (THz) frequencies to demonstrate its validity.

Jin Zhou, Yong; Jun Cui, Tie

2011-09-01

223

Modified DSTATCOM Topology with Reduced DC Link Voltage for Reactive and Harmonic Power Compensation of Unbalanced Nonlinear Load in Distribution System  

NASA Astrophysics Data System (ADS)

This paper proposes a modified four-leg distribution static compensator (DSTATCOM) topology for compensation of unbalanced and nonlinear loads in three-phase four-wire distribution system. DSTATCOM, connected in parallel to the load, supplies reactive and harmonic powers demanded by unbalanced nonlinear loads. In this proposed topology, the voltage source inverter (VSI) of DSTATCOM is connected to point of common coupling (point of interconnection of source, load, DSTATCOM) through interface inductor and series capacitance, unlike the conventional topology which consists of interface inductor alone. Load compensation with a lower value of input DC link voltage of VSI is possible in this modified topology compared to conventional topology. A comparative study on modified and conventional topologies in terms of voltage rating of inverter power switches, switching losses in VSI and power rating of input DC capacitor of VSI is presented. The detailed design aspects of DC link capacitor and interface series capacitor are also presented. The reference filter currents are generated using instantaneous symmetrical component theory and are tracked using hysteresis current control technique. A detailed simulation study is carried out, to compare the compensation performances of conventional, modified topologies using PSCAD simulator and experimental studies are done to validate the simulation results.

Geddada, Nagesh; Karanki, Srinivas B.; Mishra, Mahesh K.

2014-06-01

224

Description of the SSF PMAD DC testbed control system data acquisition function  

NASA Technical Reports Server (NTRS)

The NASA LeRC in Cleveland, Ohio has completed the development and integration of a Power Management and Distribution (PMAD) DC Testbed. This testbed is a reduced scale representation of the end to end, sources to loads, Space Station Freedom Electrical Power System (SSF EPS). This unique facility is being used to demonstrate DC power generation and distribution, power management and control, and system operation techniques considered to be prime candidates for the Space Station Freedom. A key capability of the testbed is its ability to be configured to address system level issues in support of critical SSF program design milestones. Electrical power system control and operation issues like source control, source regulation, system fault protection, end-to-end system stability, health monitoring, resource allocation, and resource management are being evaluated in the testbed. The SSF EPS control functional allocation between on-board computers and ground based systems is evolving. Initially, ground based systems will perform the bulk of power system control and operation. The EPS control system is required to continuously monitor and determine the current state of the power system. The DC Testbed Control System consists of standard controllers arranged in a hierarchical and distributed architecture. These controllers provide all the monitoring and control functions for the DC Testbed Electrical Power System. Higher level controllers include the Power Management Controller, Load Management Controller, Operator Interface System, and a network of computer systems that perform some of the SSF Ground based Control Center Operation. The lower level controllers include Main Bus Switch Controllers and Photovoltaic Controllers. Power system status information is periodically provided to the higher level controllers to perform system control and operation. The data acquisition function of the control system is distributed among the various levels of the hierarchy. Data requirements are dictated by the control system algorithms being implemented at each level. A functional description of the various levels of the testbed control system architecture, the data acquisition function, and the status of its implementationis presented.

Baez, Anastacio N.; Mackin, Michael; Wright, Theodore

1992-01-01

225

DC current distribution mapping system of the solar panels using a HTS-SQUID gradiometer  

NASA Astrophysics Data System (ADS)

Solar panels are expected to play a major role as a source of sustainable energy. In order to evaluate solar panels, non-destructive tests, such as defect inspections and response property evaluations, are necessary. We developed a DC current distribution mapping system of the solar panels using a High Critical Temperature Superconductor Superconducting Quantum Interference Device (HTS-SQUID) gradiometer with ramp edge type Josephson junctions. Two independent components of the magnetic fields perpendicular to the panel surface (?Bz/?x, ?Bz/?y) were detected. The direct current of the solar panel is visualized by calculating the composition of the two signal components, the phase angle, and mapping the DC current vector. The developed system can evaluate the uniformity of DC current distributions precisely and may be applicable for defect detection of solar panels.

Miyazaki, Shingo; Kasuya, Syohei; Mawardi Saari, Mohd; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Tsukada, Keiji

2014-05-01

226

Interaction between MHD generator and dc-ac power conversion system  

NASA Astrophysics Data System (ADS)

Transient characteristics of an MHD power generating system including a DC-AC inverter are analyzed using a time-dependent quasi-one-dimensional approximation. The generator model considered is Faraday type of U-25 class with heavy-oil and air combustion gas. It is found that a short-circuited fault of the invertor may become more serious than an open-circuited fault, resulting in significant gas velocity reduction. An open-circuited fault, if retained for more than 5-8 ms, can substantially increase the gas velocity at the upstream end of the fault region. A protection system composed of a fast-acting DC circuit-breaker and an emergency load resistance is proposed. The switching speed of the DC breaker must be about 500 microsec to stop a pressure increase, resulting, for example, from the short-circuiting of 20 electrode pairs, before it reaches 120% of the initial level.

Tanaka, D.

1983-10-01

227

DC brushless motor and ITS driving control system  

SciTech Connect

A direct current brushless motor is structured by fixing a ring-shape magnetic rotor to a rotor shaft in one piece by way of the magnet yoke, and by arranging the position of the insulating plate on which the magnetic induction elements for detecting the magnetic field of the rotor magnet, stator windings and the rotor yoke are installed, so as to have the rotor magnet oppose the stator windings across an air gap. The stator windings are composed of delta connection wirings and the windings of each phase are placed on a concentric circle having the rotor shaft at its center and in a position dividing the said circle in equiangular areas. The magnetic induction elements are provided in three with the first, second and third elements being respectively fixed at the positions where their respective phases are advanced by ..pi../6 radian in the electric angle from the respective centers of the first phase, second phase and third phase coils. These magnetic induction elements pick up only the plus-side output signals and let the current flow respectively to the aforesaid three-phased stator windings through an amplifier, whereby they form a driving circuit for driving said rotor shaft.

Hagino, H.; Kotake, E.; Nakamura, K.

1984-03-06

228

Quantum-classical correspondence for a dc-biased cavity resonator--Cooper-pair transistor system  

E-print Network

We investigate the quantum versus classical dynamics of a microwave cavity-coupled-Cooper pair transistor (CPT) system, where an applied dc bias causes the system to self-oscillate via the ac Josephson effect. Varying the dc bias allows the self-oscillation frequency to be tuned. An unusual feature of the system design is that the dc bias does not significantly affect the high quality factor of the cavity mode to which the CPT predominantly couples. The CPT-cavity mode system has a mechanical analogue involving a driven coupled pendulum-oscillator system. The corresponding, nonlinear classical dynamical equations exhibit chaotic, as well as aperiodic motions depending on the initial conditions and the nature and strengths of the damping/noise forces. The quantum master equation exhibits such phenomena as dynamical tunneling and the generation of non-classical states from initial classical states. Obviating the need for an external ac-drive line, which typically is harder to noise filter than a dc bias line, the self-oscillating system described here has considerable promise for demonstrating macroscopic quantum dynamical behavior.

Miles Blencowe; Andrew Armour; Alex Rimberg

2011-06-29

229

Tunneling and nonlinear transport in a vertically coupled GaAs/AlGaAs double quantum wire system.  

SciTech Connect

We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a unique flip chip technique to align top and bottom split gates to form low-dimensional constrictions in each of the independently contacted quantum wells we explicitly control the subband occupation of the individual wires. In addition to the expected two-dimensional (2D)-2D tunneling results, we have found additional tunneling features that are related to the one-dimensional quantum wires.

Seamons, John Andrew; Lilly, Michael Patrick; Reno, John Louis; Bielejec, Edward Salvador

2004-11-01

230

Transient study of DC Zonal Electrical Distribution System in Next Generation Shipboard Integrated Power Systems using PSCAD™  

Microsoft Academic Search

Developing power management schemes for the Next Generation Integrated Power System (NGIPS) for ships requires an adequate model of the power system. NGIPS is the subject of ongoing research in different fields and a design handbook of this system is not available yet. This paper presents a design, modeling and simulation procedure for a DC Zonal Electrical Distribution System (ZEDS)

B. Farhangi; K. L. Butler-Purry

2009-01-01

231

Software Development for a CompactRIO-Based Wire Scanner Control and Data Acquisition SYstem  

SciTech Connect

The Beam Diagnostics and Instrumentation Team at the Los Alamos Neutron Science Center is developing a wire scanner data acquisition and control system with a National Instrument's compactRIO at its core. For this application, the compactRIO controller not only requires programming the FPGA and RT computer internal to the compactRIO, but also requires programming a client computer and a touch panel display. This article will summarize the hardware interfaces and describe the software design approach utilized for programming and interfacing the four systems together in order to fulfill the design requirements and promote reliable interoperability.

Sedillo, James Daniel [Los Alamos National Laboratory

2012-05-16

232

A High Efficiency DC-DC Converter Topology Suitable for Distributed Large Commercial and Utility Scale PV Systems  

SciTech Connect

In this paper a DC-DC power converter for distributed photovoltaic plant architectures is presented. The proposed converter has the advantages of simplicity, high efficiency, and low cost. High efficiency is achieved by having a portion of the input PV power directly fed forward to the output without being processed by the converter. The operation of this converter also allows for a simplified maximum power point tracker design using fewer measurements

Mohammed S. Agamy; Maja Harfman-Todorovic; Ahmed Elasser; Robert L. Steigerwald; Juan A. Sabate; Song Chi; Adam J. McCann; Li Zhang; Frank Mueller

2012-09-01

233

Design of a high voltage input - output ratio dc-dc converter dedicated to small power fuel cell systems  

NASA Astrophysics Data System (ADS)

Consuming chemical energy, fuel cells produce simultaneously heat, water and useful electrical power [J.M. Andújar, F. Segura, Renew. Sust. Energy Rev. 13, 2309 (2009)], [J. Larminie, A. Dicks, Fuel Cell Systems Explained, 2nd edn. (John Wiley & Sons, 2003)]. As a matter of fact, the voltage generated by a fuel cell strongly depends on both the load power demand and the operating conditions. Besides, as a result of many design aspects, fuel cells are low voltage and high current electric generators. On the contrary, electric loads are commonly designed for small voltage swing and a high V/I ratio in order to minimize Joule losses. Therefore, electric loads supplied by fuel cells are typically fed by means of an intermediate power voltage regulator. The specifications of such a power converter are to be able to step up the input voltage with a high ratio (a ratio of 10 is a classic situation) and also to work with an excellent efficiency (in order to minimize its size, its weight and its losses) [A. Shahin, B. Huang, J.P. Martin, S. Pierfederici, B. Davat, Energy Conv. Manag. 51, 56 (2010)]. This paper deals with the design of this essential ancillary device. It intends to bring out the best structure for fulfilling this function. Several dc-dc converters with large voltage step-up ratios are introduced. A topology based on a coupled inductor or tapped inductor is closely studied. A detailed modelling is performed with the purpose of providing designing rules. This model is validated with both simulation and implementation. The experimental prototype is based on the following specifications: the fuel cell output voltage ranges from a 50 V open-voltage to a 25 V rated voltage while the load requires a constant 250 V voltage. The studied coupled inductor converter is compared with a classic boost converter commonly used in this voltage elevating application. Even though the voltage regulator faces severe FC specifications, the measured efficiency reaches 96% at the rated power whereas conventional boost efficiency barely achieves 91.5% in the same operating conditions.

Béthoux, O.; Cathelin, J.

2010-12-01

234

Design and construction evaluation of a photovoltaic DC LED lighting system  

NASA Astrophysics Data System (ADS)

The market demand for commercialization of Photovoltaic (PV) systems depends a lot on the reliability, efficiency and performance of various components within the system. PV panels produce DC power when exposed to sunlight, and an inverter converts this to AC power in a typical solar powered building. Though, PV lighting has existed for a long time it hasn't been very effective, as incandescent light sources were commonly used which are inefficient. Today fluorescent fixtures are mostly used with PV's due to its high efficacy. Light-emitting diodes present a new vision to energy efficiency in lighting design with their low energy consumption. Current research predicts improved efficiencies of LED light fixtures and their commercial use is a few years away. LEDs which operate on DC voltages when coupled with photovoltaics can be a simple PV lighting application and a sustainable solution with potential for payback. This research evaluates the design and construction of a photovoltaic DC LED lighting system for a solar house at Pennsylvania State University. A detailed cost and payback analysis of a PV DC LED lighting system is presented in this research. PV output simulations for the solar house are presented. Results presented in this research indicate that the Solid state lighting market is evolving rapidly and that LED's are a choice in stand-alone photovoltaic DC lighting systems. The efficiency and the cost-effectiveness of such systems would however improve in the coming years with research and development now focused on PV systems and on Solid state lighting technologies.

Bhamidipati, Jyotsna

2008-08-01

235

Basic Wiring.  

ERIC Educational Resources Information Center

This module is the first in a series of three wiring publications; it serves as the foundation for students enrolled in a wiring program. It is a prerequisite to either "Residential Wiring" or "Commercial and Industrial Wiring." The module contains 16 instructional units that cover the following topics: occupational introduction; general safety;…

Kaltwasser, Stan; And Others

236

Development of ultra-precision machining system with unique wire EDM tool fabrication system for micro\\/nano-machining  

Microsoft Academic Search

Aiming at quality machining of very hard materials with nanometer level surface quality and 0.1?m dimensional accuracy, an ultra-precision machining system has been developed. The machine has feed axes accompanied by the counter motion mechanism driven at the center of gravity to eliminate the vibration caused by high acceleration\\/deceleration. A custom tool fabrication system consists of a 6-axis wire EDM

X. Cheng; K. Nakamoto; M. Sugai; S. Matsumoto; Z. G. Wang; K. Yamazaki

2008-01-01

237

Superconductivity for Electric Systems Annual Peer Review Washington, DC July 27-29, 2004. OAK RIDGE NATIONAL LABORATORY  

E-print Network

Superconductivity for Electric Systems Annual Peer Review Washington, DC ­ July 27-29, 2004. OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY American Superconductor Corporation U. Schoop, M. W&D support #12;Superconductivity for Electric Systems Annual Peer Review Washington, DC ­ July 27-29, 2004

238

Abstract--Many studies comparing AC and DC systems have focused on efficiency, stability, and controllability, but have not  

E-print Network

buffering and a control algorithm for the converters as ways to elevate the negative incremental impedance for droop control. The authors implement the existing converters in the DC system to perform load sharingAbstract--Many studies comparing AC and DC systems have focused on efficiency, stability

Tolbert, Leon M.

239

Development of a computer assistant programming system for micro\\/nano milling tool fabrication by multi-axis wire EDM  

Microsoft Academic Search

Micro\\/nano milling tools are usually made of ultra hard materials. Wire EDM (electrical discharge machining) may be the best choice to fabricate these tools conveniently and efficiently. For micro\\/nano milling tools with complicated three-dimensional (3D) geometries, manually programming method is not applicable. The CAM (computer-aided manufacturing) systems existing in the market don't take the special WEDM (Wire EDM) processes for

Xiang Cheng; Zhigang Wang; Shigeru Kobayashi; Kazuo Nakamoto; Kazuo Yamazaki

2009-01-01

240

A System for Speed and Torque Control of DC Motors with Application to Small Snake Robots  

E-print Network

A System for Speed and Torque Control of DC Motors with Application to Small Snake Robots Ankur equipped with small snake-like mechanisms, which challenge the controller design due to their requirement snake-like mechanism because it placed the most demands on the design of the low level controller, which

Simaan, Nabil

241

Modelling of AC\\/DC\\/AC conversion systems with PWM inverter  

Microsoft Academic Search

Modelling of AC\\/DC\\/AC power conversion systems with PWM inverters is considered and a new model is presented and discussed. The new model is based on the modulation function theory and uses the iterative harmonic and interharmonic analysis (IHIA), taking advantage of a new inverter model. The proposed model can be applied successfully to adjustable speed drives (ASD) for asynchronous motors,

Rosario Carbone; F. De Rosa; R. Langella; A. Sollazzo; A. Testa

2002-01-01

242

Analysis and modeling of a single-phase brushless DC motor drive system  

Microsoft Academic Search

A single-phase brushless DC motor drive system with a bifilar stator winding and asymmetrical stator pole faces is investigated. The form of the permanent-magnet component of the stator winding flux linkage is analyzed considering the asymmetry of the stator pole faces. Equations describing the electromechanical dynamics of the motor are then derived along with an expression for the electromagnetic torque.

J. S. Mayer; O. Wasynczuk

1989-01-01

243

Concept for a 48 V DC Power Supply System with Lithium Ion Batteries for Telecom Applications  

Microsoft Academic Search

The DC power supply systems of telecom applications for broadband and Internet access have increasing energy demands. However, in many cases the available space for the installation is already used to its maximum. A lithium ion battery can be the solution because of the higher energy density of about 150 Wh\\/kg and 380 Wh\\/l, good discharging performance and an operating

Markus Schweizer-Berberich; Hartwig Willmes

2005-01-01

244

Spatiotemporal patterns in a dc semiconductor-gas-discharge system: Stability analysis and full numerical solutions  

E-print Network

Spatiotemporal patterns in a dc semiconductor-gas-discharge system: Stability analysis and full by sandwiching a gas discharge and a high-ohmic semiconductor layer between two planar electrodes. In experiments in a technical process. Pattern formation occurs frequently in gas discharges, like in dielectric barrier

Ebert, Ute

245

A workstation based Langmuir probe system for low-pressure dc plasmas  

Microsoft Academic Search

A Langmuir probe measurement system suitable for characterization of extended, low-pressure dc or microwave plasmas has been developed around a VAXStation 3200 graphics workstation computer. Both planar and cylindrical probes have been constructed, but the latter has been deemed more satisfactory, and its design developed more fully. A novel interface circuit based on fast high voltage, transformer-coupled, isolation amplifiers has

Isaac D. Sudit; R. Claude Woods

1993-01-01

246

An Analog Computer Study of a Parallel AC and DC Power System  

Microsoft Academic Search

Overall critical evaluation of the dynamics of EHV dc-power transmission requires that a variety of system conditions and effects of many parameters be studied. Problems can be strictly electrical or electromechanical. In general, those that fall in the former category are of short time duration, while those in the latter may be either of intermediate duration, on the order of

H. A. Peterson; P. C. Jr. Krause; J. F. Luini; C. H. Thomas

1966-01-01

247

High frequency inverter-cycloconverter system for dc to ac conversion  

Microsoft Academic Search

A high frequency inverter-cycloconverter system for dc to ac conversion was studied. The primary stage produces a high frequency square wave (500 Hz) which is reduced to a lower frequency (50 Hz) by a cycloconverter which applies a sinusoidally weighted phase controlled technique to produce a pwm-like output. The modulation strategy is presented and harmonic analysis of the positive, negative

M. R. D. Al-Mothafar

1987-01-01

248

An Improved DC-Link Voltage Control Method for Multiple Grid Connected Converter in Direct Drive Wind Power Generation System  

Microsoft Academic Search

In order to reduce the current of each IGBT and reduce the harmonic current into the grid, a multiple AC-DC-AC full-scale converter which is suitable for high power direct drive wind power generation systems is adopted. The reasons of DC-link voltage fluctuation of the grid connected converter are analyzed. An improved DC-link voltage control method for multiple grid connected converter

Weihao Hu; Yue Wang; Xianwen Song; Zhaoan Wang

2009-01-01

249

Desicription and flight test results of the NASA F-8 digital fly-by-wire control system  

NASA Technical Reports Server (NTRS)

A NASA program to develop digital fly-by-wire (DFBW) technology for aircraft applications is discussed. Phase I of the program demonstrated the feasibility of using a digital fly-by-wire system for aircraft control through developing and flight testing a single channel system, which used Apollo hardware, in an F-8C airplane. The objective of Phase II of the program is to establish a technology base for designing practical DFBW systems. It will involve developing and flight testing a triplex digital fly-by-wire system using state-of-the-art airborne computers, system hardware, software, and redundancy concepts. The papers included in this report describe the Phase I system and its development and present results from the flight program. Man-rated flight software and the effects of lightning on digital flight control systems are also discussed.

1975-01-01

250

Mechanical considerations in using tensioned wires in a transosseous external fixation system.  

PubMed

Factors that affect wire tension were examined using external mechanical testing units as well as in-line load cells. The circular external fixator with wires supported at each end exhibits a self-stiffening effect such that wire stiffness increases with wire deflection. Mechanical slippage between wire and fixation bolt is the primary reason for loss of wire tension. Slippage can be avoided by adequate torque on the fixation nut (20 N.m). Guidelines are presented for proper and safe tensioning techniques to achieve clinically indicated tensions without risk of breakage. PMID:1611749

Aronson, J; Harp, J H

1992-07-01

251

Feedback stabilization for AC\\/DC power system with nonlinear loads  

Microsoft Academic Search

In view of the nonlinearity of loads and HVDC in power systems, the M derivative, M bracket and multi-input multi-output (MIMO) feedback linearization based on nonlinear differential algebraic system (NDAS) are introduced into the design of nonlinear controller for parallel AC\\/DC power system. Bronovsky normal form for NDAS is derived when the M relative degree of NDAS is less than

Guanghu Xu; Jie Wang; Chen Chen

2005-01-01

252

The state-of-the-art of dc power distribution systems/components for space applications  

NASA Technical Reports Server (NTRS)

This report is a survey of the state of the art of high voltage dc systems and components. This information can be used for consideration of an alternative secondary distribution (120 Vdc) system for the Space Station. All HVdc components have been prototyped or developed for terrestrial, aircraft, and spacecraft applications, and are applicable for general space application with appropriate modification and qualification. HVdc systems offer a safe, reliable, low mass, high efficiency and low EMI alternative for Space Station secondary distribution.

Krauthamer, S.

1988-01-01

253

LANSCE-R WIRE-SCANNER ANALOG FRONT-END ELECTRONICS  

SciTech Connect

A new AFE is being developed for the new LANSCE-R wire-scanner systems. The new AFE is implemented in a National Instruments Compact RIO (cRIO) module installed a BiRa 4U BiRIO cRIO chassis specifically designed to accommodate the cRIO crate and all the wire-scanner interface, control and motor-drive electronics. A single AFE module provides interface to both X and Y wire sensors using true DC coupled transimpedance amplifiers providing collection of the wire charge signals, real-time wire integrity verification using the normal dataacquisition system, and wire bias of 0V to +/-50V. The AFE system is designed to accommodate comparatively long macropulses (>1ms) with high PRF (>120Hz) without the need to provide timing signals. The basic AFE bandwidth is flat from true DC to 50kHz with a true first-order pole at 50kHz. Numeric integration in the cRIO FPGA provides real-time pulse-to-pulse numeric integration of the AFE signal to compute the total charge collected in each macropulse. This method of charge collection eliminates the need to provide synchronization signals to the wire-scanner AFE while providing the capability to accurately record the charge from long macropulses at high PRF.

Gruchalla, Michael E. [Los Alamos National Laboratory

2011-01-01

254

The SpaceWire-based thermal infrared imager system for asteroid sample return mission HAYABUSA2  

NASA Astrophysics Data System (ADS)

Thermal infrared imager system is developed for HAYABUSA2, which is planned to be launched in 2014 and aims at sample-return from a C class near-Earth asteroid 1999JU3 considered to contain organic or hydrated materials. The system consists of a thermal-infrared imager (TIR) and a digital electronics, which is used not only for the scientific investigation of physical properties of the asteroid surface, but also for the assessment of landing site selection and safe descent operation onto the asteroid surface with in situ measurement. Since round trip communication time between the asteroid and the Earth is more than thirty minutes, onboard automatic data processing function and high speed data recording capability are provided to exploit the limited downlink capacity which is up to 32kbps. TIR adopts an uncooled bolometer with 320 x 240 effective pixels. Image operations as multiple images summation, dark image subtraction, and the compensation of dead pixels are processed onboard. A processing module is connected to sensor interfaces through SpaceWire in order to provide deterministic processing time. Data compression is also provided to reduce restriction on storage capacity and operation time, which provides the equivalent compression ratio as JPEG2000 in 1/30 processing time in average. A high speed data recorder is also connected through SpaceWire in 50Mbps in order to record TIR data in parallel with other sensor data. The modularity of SpaceWire enables to use as built devices for TIR and inherits the same design as the long-wavelength infrared imager developed for the Venus climate orbiter Akatsuki.

Otake, Hisashi; Okada, Tatsuaki; Funase, Ryu; Hihara, Hiroki; Sano, Junpei; Iwase, Kaori; Kashikawa, Ryoichi; Higashino, Isamu; Masuda, Tetsuya

2013-09-01

255

DC/AC Student Guide: Solar Energy Power System  

NSDL National Science Digital Library

The purpose of this lab is to be able to measure and calculate basic values such as voltage, current, power, and efficiencies for a power system. Alternative energy is a hot topic these days and much emphasis is being placed on being "green." A "green" system is one that was intentionally designed with high-energy efficiency in mind and also that it be more environmental friendly that previous systems. As time passes more and more alternative energy systems will be placed "on-line." A technician must have the skills to measure such systems and determine if components are in need of replacement and if the systems are operating within operating specifications. Users must create a free account to download this resource.

256

Magnification of starting torques of dc motors by maximum power point trackers in photovoltaic systems  

NASA Technical Reports Server (NTRS)

Direct current (dc) motors are used in terrestrial photovoltaic (PV) systems such as in water-pumping systems for irrigation and water supply. Direct current motors may also be used for space applications. Simple and low weight systems including dc motors may be of special interest in space where the motors are directly coupled to the solar cell array (with no storage). The system will operate only during times when sufficient insolation is available. An important performance characteristic of electric motors is the starting to rated torque ratio. Different types of dc motors have different starting torque ratios. These ratios are dictated by the size of solar cell array, and the developed motor torque may not be sufficient to overcome the load starting torque. By including a maximum power point tracker (MPPT) in the PV system, the starting to rated torque ratio will increase, the amount of which depends on the motor type. The starting torque ratio is calculated for the permanent magnet, series and shunt excited dc motors when powered by solar cell arrays for two cases: with and without MPPT's. Defining a motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 was obtained for the permanent magnet motor and a magnification of 7 for both the series and shunt motors. The effect of the variation of solar insolation on the motor starting torque was covered. All motor types are less sensitive to insolation variation in systems including MPPT's as compared to systems with MPPT's. The analysis of this paper will assist the PV system designed to determine whether or not to include an MPPT in the system for a specific motor type.

Appelbaum, Joseph; Singer, S.

1989-01-01

257

Digital Wires  

NASA Astrophysics Data System (ADS)

We study hardware implementations of cellular automata as reliable, adjustable, and secure commication lines. We discuss energy efficient digital wires on a nano-scale, all-optical digital wires, and digital wires as power lines and present performance data of a prototype digital wire, a six cells wide and ten cells long Boolean network. We show that digital wires have the following advantages: (i) Fixed pulse shape (pulses have a rectangular shape with a constant height and a constant width and produce no echos); (ii) Robust against electric smog. Digital wires based on semiconductor technology are effectively inert against electro-magnetic radiation, except for low-frequency radiation (heat) and high frequency radiation (X-rays). Digital wires based on plasma technology have in addition a very high tolerance for heat and X-rays. In digital wire the pulse speed can be rapidly adjusted. Signals on digital wires can be encrypted. Some digital wires can be used as general purpose computers. The data and the code are the input of the wire. Then both travel along the wire and `collide'. The collision is the computation. The result travels to the end of the wire, for further processing, as parallel input by a CPU, an actuator, or another digital wire.

Brown, Benny; Hubler, Alfred

2009-03-01

258

A versatile DC-DC and DC-AC converter with zero current soft switching  

Microsoft Academic Search

A versatile DC-DC and DC-AC capacitively coupled power converter which is capable of zero current soft switching is presented. This converter can supply both DC and AC loads with a higher system efficiency due to its zero current switching operation. The DC output is regulated by pulse width modulation (PWM) while the AC waveform is controlled by amplitude modulation (AM)

T. S. Wu; M. Ehsani

1993-01-01

259

MIDAS, prototype Multivariate Interactive Digital Analysis System, phase 1. Volume 3: Wiring diagrams  

NASA Technical Reports Server (NTRS)

The Midas System is a third-generation, fast, multispectral recognition system able to keep pace with the large quantity and high rates of data acquisition from present and projected sensors. A principal objective of the MIDAS Program is to provide a system well interfaced with the human operator and thus to obtain large overall reductions in turn-around time and significant gains in throughput. The hardware and software generated in Phase I of the overall program are described. The system contains a mini-computer to control the various high-speed processing elements in the data path and a classifier which implements an all-digital prototype multivariate-Gaussian maximum likelihood decision algorithm operating at 2 x 100,000 pixels/sec. Sufficient hardware was developed to perform signature extraction from computer-compatible tapes, compute classifier coefficients, control the classifier operation, and diagnose operation. The MIDAS construction and wiring diagrams are given.

Kriegler, F. J.; Christenson, D.; Gordon, M.; Kistler, R.; Lampert, S.; Marshall, R.; Mclaughlin, R.

1974-01-01

260

Hybrid large scale system model for a DC microgrid  

Microsoft Academic Search

A microgrid power system with multiple energy sources and loads is considered in this paper. Such microgrids are common due to the needs of distributed generation, re- newable energy, and hybrid power sources. The system under study consists of a large number of power converters operating over a wide range of voltages and currents, interconnected via a distribution network. Stability

P. Tulpule; S. Yurkovich; J. Wang; G. Rizzoni

2011-01-01

261

A new approach to model AC\\/DC\\/AC conversion systems  

Microsoft Academic Search

A new approach for modeling AC\\/DC\\/AC power conversion systems is presented and discussed. It is based on the modulation function theory and utilizes the concept of the iterative harmonic analysis (IHA), taking advantage of a two-step procedure in which two different models are utilized. The proposed approach can be applied successfully on HVDC systems and adjustable speed drives for synchronous

R. Carbone; F. De Rosa; R. Langella; A. Testa

2001-01-01

262

Proposed design of axial injection system for the DC-280 cyclotron  

NASA Astrophysics Data System (ADS)

The design of the high-voltage axial injection system for the DC-280 cyclotron that is being constructed at the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR) is presented. The injection system will make it possible to efficiently inject ions of elements ranging from helium to uranium with the ratios of their atomic mass to the charge varying from 4 to 7.5.

Gulbekian, G. G.; Gikal, B. N.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Ivanenko, I. A.; Kazarinov, N. Yu.; Kalagin, I. V.; Melnikov, V. N.; Osipov, N. F.; Prokhorov, S. V.; Tikhomirov, A. V.; Khabarov, M. V.

2014-11-01

263

A novel resonant DC link bidirectional three phase PWM converter for battery energy storage system  

Microsoft Academic Search

In this paper, a simple prototype of a quasi-resonant DC link (QRDCL) voltage-fed bidirectional power converter operating in the zero voltage soft-switching PWM mode is presented for a battery energy storage system (BESS). The operating principle of this QRDCL circuit and multi-functional control-based power converter system, including PWM inverter mode in which energy flows through from the battery bank to

E. Hiraki; M. Kurokawa; S. Sugimoto; M. Nakaoka

1997-01-01

264

Reversible AC Drive Systems Based on Parallel AC–AC DC-Link Converters  

Microsoft Academic Search

In this paper, two reversible single-phase-to-three-phase ac drive systems are proposed. They are composed of an induction motor fed by two parallel single-phase-to-three-phase dc-link converters without isolation transformers. Suitable modeling and control strategy of the systems based on odq approach, including the unbalanced case, are developed. The proposed topologies permit reducing the harmonic distortion and presents fault tolerance characteristics. Even

Cursino Brandão Jacobina; Euzeli Cipriano dos Santos; Nady Rocha; Bernard de S Gouveia; Edison Roberto Cabral da Silva

2010-01-01

265

Effect of converter DC fault on the transient stability of a Multi-Machine Power System with HVDC transmission lines  

Microsoft Academic Search

This paper deals with the effect of DC faults on the transient stability of a multi-machine power system with two transmission line configurations; HVDC and a hybrid HVAC-HVDC transmission line. The faults are located at the DC terminals of the HVDC converter station. In order to carry out this study, two case studies are presented. In the first case study

D. T. Oyedokun; K. A. Folly; S. P. Chowdhury

2009-01-01

266

A comparative analysis of three-phase four-wire UPQC topologies  

Microsoft Academic Search

The unified power quality conditioner (UPQC) is a power conditioning device, which is a integration of back to back connected shunt active power filter (APF) and series APF to a common DC link voltage. For improvement of power quality (PQ) problems in a three-phase four-wire distribution system, two topologies are proposed in this paper. A comparative analysis of these topologies

Yash Pal; A. Swarup; Bhim Singh

2010-01-01

267

Nonlinear control of voltage source converters in AC-DC power system.  

PubMed

This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations. PMID:24906895

Dash, P K; Nayak, N

2014-07-01

268

Annular suspension and pointing system with controlled DC electromagnets  

NASA Technical Reports Server (NTRS)

The Annular Suspension and Pointing System (ASPS) developed by the Flight System division of Sperry Corporation is a six-degree of freedom payload pointing system designed for use with the space shuttle. This magnetic suspension and pointing system provides precise controlled pointing in six-degrees of freedom, isolation of payload-carrier disturbances, and end mount controlled pointing. Those are great advantages over the traditional mechanical joints for space applications. In this design, we first analyzed the assumed model of the single degree ASPS bearing actuator and obtained the plant dynamics equations. By linearizing the plant dynamics equations, we designed the cascade and feedback compensators such that a stable and satisfied result was obtained. The specified feedback compensator was computer simulated with the nonlinearized plant dynamics equations. The results indicated that an unstable output occurred. In other words, the designed feedback compensator failed. The failure of the design is due to the Taylor's series expansion not converging.

Vu, Josephine Lynn; Tam, Kwok Hung

1993-01-01

269

Research study on multi-KW DC distribution system  

NASA Technical Reports Server (NTRS)

Power distribution system noise and transient stress on switchgear in large space vehicle power systems were investigated in terms of the effect of flight designs of long power distribution cables on load interface EMI requirements. A fifty meter cable pair was simulated to study interactions between the cable, load, and power source terminations. Power system noise characteristics were evaluated based on current spacecraft data, interface hardware filter designs, and power cable parameters. Parametric approaches were defined for evaluating switching transients at various distribution voltage levels. It is concluded that the state-of-the-art semiconductor switches represent a viable approach toward the implementation of power system design with distribution voltages of 120 VDC or less. The interface definition and design for the bus control unit was updated to be consistent with the established requirements.

Berkery, E. A.

1975-01-01

270

A low cost, DC-coupled active vibration isolation system  

E-print Network

In this thesis, I designed and implemented an isolation system that interfaces with traditional air mounts for improved force disturbance rejection relative to passive optical tables.Force disturbance rejection and position ...

Miu, Kevin Kar-Leung

2008-01-01

271

Brushless DC motor control system responsive to control signals generated by a computer or the like  

NASA Technical Reports Server (NTRS)

A control system for a brushless DC motor responsive to digital control signals is disclosed. The motor includes a multiphase wound stator and a permanent magnet rotor. The motor is arranged so that each phase winding, when energized from a DC source, will drive the rotor through a predetermined angular position or step. A commutation signal generator responsive to the shaft position provides a commutation signal for each winding. A programmable control signal generator such as a computer or microprocessor produces individual digital control signals for each phase winding. The control signals and commutation signals associated with each winding are applied to an AND gate for that phase winding. Each gate controls a switch connected in series with the associated phase winding and the DC source so that each phase winding is energized only when the commutation signal and the control signal associated with that phase winding are present. The motor shaft may be advanced one step at a time to a desired position by applying a predetermined number of control signals in the proper sequence to the AND gates and the torque generated by the motor be regulated by applying a separate control signal and each AND gate which is pulse width modulated to control the total time that each switch connects its associated winding to the DC source during each commutation period.

Packard, D. T. (inventor)

1985-01-01

272

Brushless DC motor control system responsive to control signals generated by a computer or the like  

NASA Technical Reports Server (NTRS)

A control system for a brushless DC motor responsive to digital control signals is disclosed. The motor includes a multiphase wound stator and a permanent magnet rotor. The rotor is arranged so that each phase winding, when energized from a DC source, will drive the rotor through a predetermined angular position or step. A commutation signal generator responsive to the shaft position provides a commutation signal for each winding. A programmable control signal generator such as a computer or microprocessor produces individual digital control signals for each phase winding. The control signals and commutation signals associated with each winding are applied to an AND gate for that phase winding. Each gate controls a switch connected in series with the associated phase winding and the DC source so that each phase winding is energized only when the commutation signal and the control signal associated with that phase winding are present. The motor shaft may be advanced one step at a time to a desired position by applying a predetermined number of control signals in the proper sequence to the AND gates and the torque generated by the motor may be regulated by applying a separate control signal to each AND gate which is pulse width modulated to control the total time that each switch connects its associated winding to the DC source during each commutation period.

Packard, Douglas T. (Inventor); Schmitt, Donald E. (Inventor)

1987-01-01

273

Recovery semantics for a DB\\/DC system  

Microsoft Academic Search

Presented is a unified, systematic view of integrity\\/recovery as it relates to a data-processing system—whether man, machine, or both. The concept, sphere of control (SOC), as a bound around a process, is developed to permit describing and solving many of the rather aggravating problems of auditability, repeatability, reproducibility, scheduling, consistency, recovery and general integrity. Identified are the relationships among resources

Charles T. Davies Jr.

1973-01-01

274

DC graphite arc furnace and diagnostic system for soils  

Microsoft Academic Search

The need for systems to treat waste materials in a new manner has prompted the formation of an {open_quotes}Industry-National Laboratory-University{close_quotes} consortium to address the issue. The partners include Electro-Pyrolysis, Inc. (EPI), Massachusetts Institute of Technology (MIT), and Pacific Northwest Laboratory (PNL). The program includes technology transfer from industry to the national laboratory and university technology transfer to the national laboratory.

J. K. Wittle; C. H. Titus; R. A. Hamilton

1994-01-01

275

DC-ATLAS: a systems biology resource to dissect receptor specific signal transduction in dendritic cells  

PubMed Central

Background The advent of Systems Biology has been accompanied by the blooming of pathway databases. Currently pathways are defined generically with respect to the organ or cell type where a reaction takes place. The cell type specificity of the reactions is the foundation of immunological research, and capturing this specificity is of paramount importance when using pathway-based analyses to decipher complex immunological datasets. Here, we present DC-ATLAS, a novel and versatile resource for the interpretation of high-throughput data generated perturbing the signaling network of dendritic cells (DCs). Results Pathways are annotated using a novel data model, the Biological Connection Markup Language (BCML), a SBGN-compliant data format developed to store the large amount of information collected. The application of DC-ATLAS to pathway-based analysis of the transcriptional program of DCs stimulated with agonists of the toll-like receptor family allows an integrated description of the flow of information from the cellular sensors to the functional outcome, capturing the temporal series of activation events by grouping sets of reactions that occur at different time points in well-defined functional modules. Conclusions The initiative significantly improves our understanding of DC biology and regulatory networks. Developing a systems biology approach for immune system holds the promise of translating knowledge on the immune system into more successful immunotherapy strategies. PMID:21092113

2010-01-01

276

DC transport in two-dimensional electron systems under strong microwave illumination  

NASA Astrophysics Data System (ADS)

At low temperature (T) and weak magnetic field ( B), two dimensional electron systems (2DES) can exhibit strong 1/ B-periodic resistance oscillations on application of sufficiently strong microwave radiation. These oscillations are known as microwave induced resistance oscillations (MIROs), MIROs appearing near cyclotron resonance (CR) and its harmonics involve single photon processes and are called integer MIROs while the oscillations near CR subharmonics require multiphoton processes and are called fractional MIROs. Similar strong 1/B periodic resistance oscillations can occur due to strong dc current, and are known as Hall-field resistance oscillations (HIROs). Oscillations also occur for a combination of microwave radiation and strong dc current. In one prominent theory of MIROs, known as the displacement model, electrons make impurity-assisted transitions into higher or lower Landau levels by absorbing or emitting one or more (N) photons. In the presence of combined strong dc current and microwave radiation, electrons make transitions between Landau levels by absorbing or emitting photons followed by a space transition along the applied dc bias. The object of the dissertation is to explore how the different resistance oscillations area affected by strong microwave radiation when multiphoton processes are relevant. We used a coplanar waveguide (CPW) structure deposited on the sample, as opposed to simply placing the sample near the termination of a waveguide as is more the usual practice in this field. The CPW allows us to estimate the AC electric field (EAC) at the sample. In much of the work presented in this thesis we find that higher Nprocesses supersede the competing lower N processes as microwave power is increased. We show this in the presence and in the absence of a strong dc electric field. Finally, we look at the temperature evolution of fractional MIROs to compare the origin of the fractional MIROs with that of integer MIROs.

Chakraborty, Shantanu

277

Characteristic Analysis of DC Electric Railway Systems with Superconducting Power Cables Connecting Power Substations  

NASA Astrophysics Data System (ADS)

The application of superconducting power cables to DC electric railway systems has been studied. It could leads to an effective use of regenerative brake, improved energy efficiency, effective load sharing among the substations, etc. In this study, an electric circuit model of a DC feeding system is built and numerical simulation is carried out using MATLAB-Simulink software. A modified electric circuit model with an AC power grid connection taken into account is also created to simulate the influence of the grid connection. The analyses have proved that a certain amount of energy can be conserved by introducing superconducting cables, and that electric load distribution and concentration among the substations depend on the substation output voltage distribution.

Ohsaki, H.; Matsushita, N.; Koseki, T.; Tomita, M.

2014-05-01

278

Design and simulation of a wire position monitor for cryogenic systems in an ADS linac  

NASA Astrophysics Data System (ADS)

This paper introduces the design and simulation of a Wire Position Monitor (WPM) used in the cryogenic system of an Accelerator Driven System (ADS). The WPM is designed to monitor the contraction of cold masses during the cooling-down operation. In this paper, POISSON-2D electrostatic field software is used to calculate the best characteristic impedance for the WPM. Furthermore, the time domain signal of different end structures is theoretically analyzed and simulated. The coupling of electrodes and the influence of signal carrier size, which may influence the induced signal, are also discussed. Finally, the linearity of the induced voltage and the sensitivity of the WPM are analyzed. The time domain simulation results are consistent with the theoretical analysis. The influences of the coupling and carrier size are very small, and the linearity of the normalized voltage is good within r/2.

Zhu, Hong-Yan; Dong, Lan; Li, Bo

2014-08-01

279

Policies for Climate Change in the long Run: Wiring up the Innovation System for Eco-innovation  

E-print Network

systems for eco-innovation. 1. Introduction Global climate change is currently one of the hottest1 Policies for Climate Change in the long Run: Wiring up the Innovation System for Eco-innovation 1 399, DK-4000 Roskilde maj.munch.andersen@risoe.dk Abstract Policies for climate change have never

280

Flow gas transducer on basis of a hot wire with a nickel-titanium alloy in its flow calibration system  

Microsoft Academic Search

In our Latin American countries, little development has been carried out on medical control systems based on sensors (transducers) and actuators for our environment. This has motivated the present work. In medical applications such as breathing systems, hot wire flow sensors are already in use. Taking advantage of the sensor thermal convection, we can achieve a rapid operation using a

C. A. Mugruza Vassallo; Catdica del Perti

2001-01-01

281

Identification and adaptive neural network control of a DC motor system with dead-zone characteristics  

Microsoft Academic Search

In this paper, an adaptive control approach based on the neural networks is presented to control a DC motor system with dead-zone characteristics (DZC), where two neural networks are proposed to formulate the traditional identification and control approaches. First, a Wiener-type neural network (WNN) is proposed to identify the motor DZC, which formulates the Wiener model with a linear dynamic block in

Jinzhu Peng; Rickey Dubay

2011-01-01

282

A workstation based Langmuir probe system for low-pressure dc plasmas  

Microsoft Academic Search

The design considerations, software, and hardware of a workstation-based Langmuir probe system for low-pressure dc plasmas are presented, and some examples of measurements performed with it are given. A novel interface circuit based on fast high voltage, transformer-coupled, isolation amplifiers has been constructed to permit probing of regions where the plasma potential is hundreds of volts away from ground, which

Isaac D. Sudit; R. C. Woods

1993-01-01

283

An extended-state observer based system of brushless DC motor using fuzzy logic  

Microsoft Academic Search

com.cn Abstract-Brushle ss DC (BLDC) motors are widely used in vehicles because of its superior performance. The load disturbances in a BLDC have great influence on system performance. Some complex algorithms were proposed to overcome the deficiency are difficult to implement on a single DSP chip but they are not easy to implement. To solve the problem, an extended-state observer

Baifen Liul; Ying Gao

2011-01-01

284

High Performance Vertical Transition from DC to 70 GHz for System-on-Package Applications  

Microsoft Academic Search

High performance vertical transition from DC to 70 GHz was proposed for system-on-package (SoP) applications. The trough line, slab line and shielded multilayer coplanar waveguides were employed to minimize the radiation loss, crosstalk and discontinuity of a conventional via vertical transition. The half square via pad was used in order to prevent unwanted coupling between the transmission lines of the

Inkwon Ju; In-bok Yom; Ho-sin Lee; Seung-hyeup Oh

2008-01-01

285

Interaction between MHD generator and DC-AC power conversion system  

Microsoft Academic Search

Transient characteristics of an MHD power generating system including a DC-AC inverter are analyzed using a time-dependent quasi-one-dimensional approximation. The generator model considered is Faraday type of U-25 class with heavy-oil and air combustion gas. It is found that a short-circuited fault of the invertor may become more serious than an open-circuited fault, resulting in significant gas velocity reduction. An

D. Tanaka

1982-01-01

286

Z .Diamond and Related Materials 10 2001 370 375 Diamond deposition in a DC-arc Jet CVD system  

E-print Network

formation in these diamond CVD systems. Films grown in the present study have been analysed Z .by scanningZ .Diamond and Related Materials 10 2001 370 375 Diamond deposition in a DC-arc Jet CVD system of the chemical vapour deposition of diamond films at growth rates )100 m hy1 with a 10-kW DC-arc jet system are Z

Bristol, University of

287

NO removal characteristics of a corona radical shower system under DC and AC\\/DC superimposed operations  

Microsoft Academic Search

In this paper, the effects of the applied voltage modes on the positive corona discharge morphology and NO removal characteristics from air streams are experimentally investigated. By using a DC superimposed high frequency AC power supply (10-60 kHz), a uniform streamer corona can be generated, which is also less sensitive to electrode mis-arrangements. Hermstein glow can he transferred to streamer

Keping Yan; Takashi Yamamoto; Seiji Kanazawa; Toshikazu Ohkubo; Yukiharu Nomoto; Jen-Shih Chang

2001-01-01

288

Identification and adaptive neural network control of a DC motor system with dead-zone characteristics.  

PubMed

In this paper, an adaptive control approach based on the neural networks is presented to control a DC motor system with dead-zone characteristics (DZC), where two neural networks are proposed to formulate the traditional identification and control approaches. First, a Wiener-type neural network (WNN) is proposed to identify the motor DZC, which formulates the Wiener model with a linear dynamic block in cascade with a nonlinear static gain. Second, a feedforward neural network is proposed to formulate the traditional PID controller, termed as PID-type neural network (PIDNN), which is then used to control and compensate for the DZC. In this way, the DC motor system with DZC is identified by the WNN identifier, which provides model information to the PIDNN controller in order to make it adaptive. Back-propagation algorithms are used to train both neural networks. Also, stability and convergence analysis are conducted using the Lyapunov theorem. Finally, experiments on the DC motor system demonstrated accurate identification and good compensation for dead-zone with improved control performance over the conventional PID control. PMID:21788017

Peng, Jinzhu; Dubay, Rickey

2011-10-01

289

Advanced Medium-Voltage Bidirectional DC-DC Conversion Systems for Future Electric Energy Delivery and Management Systems  

Microsoft Academic Search

The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed

Haifeng Fan

2011-01-01

290

High-speed micro electrode tool fabrication by a twin-wire EDM system  

Microsoft Academic Search

This paper describes a new machining process which combines twin-electro-wire together with two electro discharge circuits to rapidly fabricate micro electrode tools. The results show that transistor electro discharge and RC electro discharge circuits coexist to fabricate micro tools with rough and finish machining both on the same machine. Compared to conventional wire electro discharge grinding (WEDG) technology, a twin-wire

Dong-Yea Sheu

2008-01-01

291

Final Results of the Protected Superficial Femoral Artery Trial Using the FilterWire EZ System  

SciTech Connect

The purpose of this study was to evaluate the safety and efficacy of debris-capture for distal protection using the FilterWire EZ Embolic Protection System (Boston Scientific, Mountain View, CA) with the additional aim to further define the incidence of distal embolization during superficial femoral artery (SFA) interventions. A prospective, single-centre registry was designed to evaluate the performance of the FilterWire EZ in capturing debris during standard SFA percutaneous intervention. The PRO-RATA study included 30 patients suitable for PTA (Fontaine IIb to III or Rutherford I to II classification). The primary end points were occurrence of distal embolization or decreased runoff, improvement in ankle-brachial index ankle-brachial index (ABI) after the procedure, and number of filters containing emboli. Secondary end points included major adverse events (i.e., procedure- or device-related death and/or clinical target lesion revascularisation), device delivery, deployment success, and incidence of embolic recovery (patients with device success exhibiting embolic protection in the filter). Procedural success was determined as {<=}30% residual stenosis with no worsening of distal runoff as determined on angiography. A total of 29 patients (age 66.2 {+-} 12 years; total no. of limbs = 30; total no. of lesions = 30) suitable for PTA were enrolled in the study between February 2007 and March 2008. There were 26 patients with claudication (Fontaine IIB) and 3 patients with stage IV peripheral vascular disease. In one patient, lesions in both legs were treated. No procedural or device-related complications occured. The average degree of stenosis was 86 {+-} 7%. Stenosis length ranged from 8 to 88 mm. The average degree of residual stenosis was 10 {+-} 10%. ABI improved from 0.56 {+-} 0.16 to 0.92 {+-} 0.19 (P < 0.05). No restenosis or dissection was seen at 1-month ultrasound follow-up. Macroscopic debris was found in 27 of 30 filters of all distal protection devices used in all 29 patients. Debris particle size ranged from 90 to 2000 {mu}m (1200 {+-} 640). Histological debris analysis showed platelets, erythrocytes, inflammatory cells, extracellular matrix, and cholesterol as being the major components of emboli. Additional immunochemistry showed no correlation between lesion morphology and debris components. The FilterWire EZ is easy and safe to handle. The system caused no complications. In all cases, macroscopic debris was captured. Using a distal protection device during femoropopliteal interventions has the potential to prevent migration of debris, which may be important for high-risk patients with limited distal runoff.

Mueller-Huelsbeck, Stefan, E-mail: muehue@diako.d [Academic Teaching Hospitals Flensburg, Department of Diagnostic and Interventional Radiology/Neuroradiology (Germany); Huemme, Tim H.; Philipp Schaefer, J.; Charalambous, Nikolas [University Hospitals Schleswig-Holstein-Campus Kiel, Department of Radiology (Germany); Paulsen, Friedrich [University of Erlangen-Nuernberg, Department of Anatomy II (Germany); Heller, Martin; Jahnke, Thomas [University Hospitals Schleswig-Holstein-Campus Kiel, Department of Radiology (Germany)

2010-12-15

292

Development of a liquid hydrogen transfer pump system with MgB2 wires  

NASA Astrophysics Data System (ADS)

An electric pump composed of an MgB2 motor is combined with superconducting level sensors using thin CuNi-sheathed MgB2 wires to transfer liquid hydrogen. An impeller is attached to the lower end of a rotating shaft on the MgB2 motor and covered with an outer casing to form a centrifugal pump. Then, the MgB2 motor and impeller are placed vertically inside a cryostat with an infill of liquid hydrogen. A glass Dewar vessel is prepared to receive the liquid hydrogen transferred from the cryostat containing the MgB2 motor. The MgB2 sensors are used not only to detect the level of liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube.

Kajikawa, Kazuhiro; Kuga, Hirotsugu; Inoue, Takuro; Watanabe, Kazuki; Uchida, Yushi; Nakamura, Taketsune; Kobayashi, Hiroaki; Hongo, Motoyuki; Kojima, Takayuki; Taguchi, Hideyuki; Naruo, Yoshihiro; Wakuda, Tsuyoshi; Tanaka, Kazuhide

293

Laser measuring system for incremental assemblies. [measuring wire-wrapped frame assemblies in spark chambers  

NASA Technical Reports Server (NTRS)

Wire-wrapped frame assemblies used in spark chambers and the like can be measured using a system which utilizes a laser, an interferometer, and a retroreflector to precisely measure distance. A light source and a photodetector are located adjacent the incremental assembly and mounted on a movable carriage. The interferometer is also mounted on the movable carriage, while the laser and retroreflector are positioned at either end of the carriage track. The carriage is moved along one edge of the incremental assembly between the retroreflector and the laser, and as the carriage is moved, the light from the light source to the photodetector is interrupted. This produces a trigger command to a control unit which in turn causes a distance measurement to be made. A printout is provided for each sampling trigger command to list such items as ideal position, actual position and amount of error.

Etzel, J. G.; Munford, J. A. (inventors)

1981-01-01

294

Cost Effective Open Geometry HTS MRI System amended to BSCCO 2212 Wire for High Field Magnets  

SciTech Connect

The original goal of this Phase II Superconductivity Partnership Initiative project was to build and operate a prototype Magnetic Resonance Imaging (MRI) system using high temperature superconductor (HTS) coils wound from continuously processed dip-coated BSCCO 2212 tape conductor. Using dip-coated tape, the plan was for MRI magnet coils to be wound to fit an established commercial open geometry, 0.2 Tesla permanent magnet system. New electronics and imaging software for a prototype higher field superconducting system would have added significantly to the cost. However, the use of the 0.2 T platform would allow the technical feasibility and the cost issues for HTS systems to be fully established. Also it would establish the energy efficiency and savings of HTS open MRI compared with resistive and permanent magnet systems. The commercial goal was an open geometry HTS MRI running at 0.5 T and 20 K. This low field open magnet was using resistive normal metal conductor and its heat loss was rather high around 15 kolwatts. It was expected that an HTS magnet would dissipate around 1 watt, significantly reduce power consumption. The SPI team assembled to achieve this goal was led by Oxford Instruments, Superconducting Technology (OST), who developed the method of producing commercial dip coated tape. Superconductive Components Inc. (SCI), a leading US supplier of HTS powders, supported the conductor optimization through powder optimization, scaling, and cost reduction. Oxford Magnet Technology (OMT), a joint venture between Oxford Instruments and Siemens and the world’s leading supplier of MRI magnet systems, was involved to design and build the HTS MRI magnet and cryogenics. Siemens Magnetic Resonance Division, a leading developer and supplier of complete MRI imaging systems, was expected to integrate the final system and perform imaging trials. The original MRI demonstration project was ended in July 2004 by mutual consent of Oxford Instruments and Siemens. Between the project start and that date a substantial shift in the MRI marketplace occurred, with rapid growth for systems at higher fields (1.5 T and above) and a consequent decline in the low field market (<1.0 T). While the project aim appeared technically attainable at that time, the conclusion was reached that the system and market economics do not warrant additional investment. The program was redirected to develop BSCCO 2212 multifilament wire development for high field superconducting magnets for NMR and other scientific research upon an agreement between DOE and Oxford Instruments, Superconducting Technology. The work t took place between September, 2004 and the project end in early 2006 was focused on 2212 multifilamentary wire. This report summarizes the technical achievements both in 2212 dip coated for an HTS MRI system and in BSCCO 2212 multifilamentary wire for high field magnets.

Kennth Marken

2006-08-11

295

Dynamical analysis of the deployable wire and probe antenna systems aboard the dual-spin satellite GEOTAIL  

NASA Astrophysics Data System (ADS)

In order to investigate the geomagnetic tail region of the magnetosphere, a joint project, called GEOTAIL, is planned between the Institute of Space and Astronautical Science (ISAS) of Japan and the United States National Aeronautics and Space Administration (NASA). The dual-spinning satellite, equipped with two pairs of wire antennas of 50 m in length, will contribute to deeper understanding of fundamental magnetospheric processes. The high degree of flexibility of the wire antennas and their dimensions may lead to undesirable wire vibrations as well as satellite attitude perturbations through in-orbit events such as antenna deployment, satellite spin-up, despun motor operation, attitude and orbital maneuvers, resulting in distortion of the attitude control accuracy and the scientific observation environment. In the study, the dynamics of dual spinning systems with highly flexible deployable wire antennas has been formulated in a relatively general manner. The associated extensive parametric analysis reveals the interactions among the attitude, orbital and vibrational dynamics as affected by wire deployment, mast extension and despun antenna operation as well as attitude and orbit maneuvers.

Morita, Y.; Hinada, M.; Kitsui, A.; Takemoto, Y.

296

An Overview of Power Electronics Applications in Fuel Cell Systems: DC and AC Converters  

PubMed Central

Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter. PMID:25478581

Ali, M. S.; Kamarudin, S. K.; Masdar, M. S.; Mohamed, A.

2014-01-01

297

An overview of power electronics applications in fuel cell systems: DC and AC converters.  

PubMed

Power electronics and fuel cell technologies play an important role in the field of renewable energy. The demand for fuel cells will increase as fuel cells become the main power source for portable applications. In this application, a high-efficiency converter is an essential requirement and a key parameter of the overall system. This is because the size, cost, efficiency, and reliability of the overall system for portable applications primarily depend on the converter. Therefore, the selection of an appropriate converter topology is an important and fundamental aspect of designing a fuel cell system for portable applications as the converter alone plays a major role in determining the overall performance of the system. This paper presents a review of power electronics applications in fuel cell systems, which include various topology combinations of DC converters and AC inverters and which are primarily used in fuel cell systems for portable or stand-alone applications. This paper also reviews the switching techniques used in power conditioning for fuel cell systems. Finally, this paper addresses the current problem encountered with DC converters and AC inverter. PMID:25478581

Ali, M S; Kamarudin, S K; Masdar, M S; Mohamed, A

2014-01-01

298

Time response simulation of the guidance and control system of an automatically steered wire-following vehicle  

NASA Technical Reports Server (NTRS)

Time-response simulation studies carried out in support of the development and validation of the guidance/steering subsystem of a wire-following-vehicle (WFV) are described. A lateral guidance system is outlined, field testing and simulation validation are covered, and time response simulation results are discussed.

Mukhopadhyay, A. K.; Dobrotin, B. M.

1979-01-01

299

A space release\\/deployment system actuated by shape memory wires  

Microsoft Academic Search

In this paper, the design of an innovative hold down\\/release and deployment device actuated by shape memory wires, to be used for the first time for the SMART microsatellite solar wings is shown. The release and deployment mechanisms are actuated by a Shape Memory wire (Nitinol), which allows a complete symmetrical and synchronous release, in a very short time, of

Marino Fragnito; Sergio Vetrella

2002-01-01

300

Magnification of starting torques of dc motors by maximum power point trackers in photovoltaic systems  

NASA Technical Reports Server (NTRS)

A calculation of the starting torque ratio of permanent magnet, series, and shunt-excited dc motors powered by solar cell arrays is presented for two cases, i.e., with and without a maximum-power-point tracker (MPPT). Defining motor torque magnification by the ratio of the motor torque with an MPPT to the motor torque without an MPPT, a magnification of 3 for the permanent magnet motor and a magnification of 7 for both the series and shunt motors are obtained. The study also shows that all motor types are less sensitive to solar insolation variation in systems including MPPTs as compared to systems without MPPTs.

Appelbaum, J.; Singer, S.

1989-01-01

301

Load converter interactions with the secondary system in the Space Station Freedom power management and distribution DC test bed  

NASA Astrophysics Data System (ADS)

The NASA LeRC in Cleveland, Ohio, is responsible for the design, development, and assembly of the Space Station Freedom (SSF) Electrical Power System (EPS). In order to identify and understand system level issues during the SSF Program design and development phases, a system Power Management and Distribution (PMAD) DC test bed was assembled. Some of the objectives of this test bed facility are the evaluation of, system efficiency, power quality, system stability, and system protection and reconfiguration schemes. In order to provide a realistic operating scenario, dc Load Converter Units are used in the PMAD dc test bed to characterize the user interface with the power system. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. This final regulation is required on the actual space station because the majority of user loads will require voltage levels different from the secondary bus voltage. This paper describes the testing of load converters in an end to end system environment (from solar array to loads) where their interactions and compatibility with other system components are considered. Some of the system effects of interest that are presented include load converters transient behavior interactions with protective current limiting switchgear, load converters ripple effects, and the effects of load converter constant power behavior with protective features such as foldback.

Lebron, Ramon C.

1992-08-01

302

Load converter interactions with the secondary system in the Space Station Freedom power management and distribution dc test bed  

NASA Astrophysics Data System (ADS)

The NASA LeRC in Cleveland, Ohio, is responsible for the design, development, and assembly of the Space Station Freedom (SSF) Electrical Power System (EPS). In order to identify and understand system level issues during the SSF program design and development phases, a system Power Management and Distribution (PMAD) dc test bed was assembled. Some of the objectives of this test bed facility are the evaluation of, system efficiency, power quality, system stability, and system protection and reconfiguration schemes. In order to provide a realistic operating scenario, dc Load Converter Units are used in the PMAD dc test bed to characterize the user interface with the power system. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. This final regulation is required on the actual space station because the majority of user loads will require voltage levels different from the secondary bus voltage. This paper describes the testing of load converters in an end to end system environment (from solar array to loads) where their interactions and compatibility with other system components are considered. Some of the system effects of interest that are presented include load converters transient behavior interactions with protective current limiting switchgear, load converters ripple effects, and the effects of load converter constant power behavior with protective features such as foldback.

Lebron, Ramon C.

303

Drive laser system for the DC-SRF photoinjector at Peking University  

E-print Network

Photoinjectors are widely used for linear accelerators as electron sources to generate high-brightness electron beam. Drive laser, which determines the timing structure and quality of the electron beam, is a crucial device of photoinjector. A new drive laser system has been designed and constructed for the upgraded 3.5-cell DC-SRF photoinjector at Peking University. The drive laser system consists of a 1064 nm laser oscillator, a four- stage amplifier, the second and fourth harmonic generators, the optical system to transfer the UV pulses to the photocathode, and the synchronization system. The drive laser system has been successfully applied in the stable operation of DC-SRF photoinjector and its performance meets the requirements. 266 nm laser with an average power close to 1W can be delivered to illuminate the Cs2Te photocathode and the instability is less than 5% for long time operation. The design consideration for improving the UV laser quality, a detailed description of laser system, and its performanc...

Wang, Zhiwen; Lin, Lin; Zhao, Gang; Quan, Shengwen; Liu, Kexin; Chen, Jiaer

2015-01-01

304

The dual-core fault-tolerant control for Electronic Control Unit of Steer-By- Wire system  

Microsoft Academic Search

In order to solve the reliability and security problems which are caused by the structural alteration to the traditional steering system, the fault diagnosis and fault-tolerant control method for the Electronic Control Unit (ECU) of Steer-By-Wire (SBW) system is studied. The architecture of the dual-core fault-tolerant control system based on the mechanisms of distributed processing and exception decision is proposed.

Lei He; Zhixin Yu; Changfu Zong; Honghui Zhao

2010-01-01

305

Next Generation Wiring  

NASA Technical Reports Server (NTRS)

Wiring is a major operational component on aerospace hardware that accounts for substantial weight and volumetric space. Over time wire insulation can age and fail, often leading to catastrophic events such as system failure or fire. The next generation of wiring must be reliable and sustainable over long periods of time. These features will be achieved by the development of a wire insulation capable of autonomous self-healing that mitigates failure before it reaches a catastrophic level. In order to develop a self-healing insulation material, three steps must occur. First, methods of bonding similar materials must be developed that are capable of being initiated autonomously. This process will lead to the development of a manual repair system for polyimide wire insulation. Second, ways to initiate these bonding methods that lead to materials that are similar to the primary insulation must be developed. Finally, steps one and two must be integrated to produce a material that has no residues from the process that degrades the insulating properties of the final repaired insulation. The self-healing technology, teamed with the ability to identify and locate damage, will greatly improve reliability and safety of electrical wiring of critical systems. This paper will address these topics, discuss the results of preliminary testing, and remaining development issues related to self-healing wire insulation.

Medelius, Petro; Jolley, Scott; Fitzpatrick, Lilliana; Vinje, Rubiela; Williams, Martha; Clayton, LaNetra; Roberson, Luke; Smith, Trent; Santiago-Maldonado, Edgardo

2007-01-01

306

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

Microsoft Academic Search

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

Malte Mohr; Friedrich W. Fuchs

2007-01-01

307

An EEG (electroencephalogram) recording system with carbon wire electrodes for simultaneous EEG-fMRI (functional magnetic resonance imaging) recording  

PubMed Central

Simultaneous EEG-fMRI (Electroencephalography-functional Magnetic Resonance Imaging) recording provides a means for acquiring high temporal resolution electrophysiological data and high spatial resolution metabolic data of the brain in the same experimental runs. Carbon wire electrodes (not metallic EEG electrodes with carbon wire leads) are suitable for simultaneous EEG-fMRI recording, because they cause less RF (radio-frequency) heating and susceptibility artifacts than metallic electrodes. These characteristics are especially desirable for recording the EEG in high field MRI scanners. Carbon wire electrodes are also comfortable to wear during long recording sessions. However, carbon electrodes have high electrode-electrolyte potentials compared to widely used Ag/AgCl (silver/silver-chloride) electrodes, which may cause slow voltage drifts. This paper introduces a prototype EEG recording system with carbon wire electrodes and a circuit that suppresses the slow voltage drift. The system was tested for the voltage drift, RF heating, susceptibility artifact, and impedance, and was also evaluated in a simultaneous ERP (event-related potential)-fMRI experiment. PMID:18588913

Negishi, Michiro; Abildgaard, Mark; Laufer, Ilan; Nixon, Terry; Constable, Robert Todd

2008-01-01

308

Description of the SSF PMAD dc testbed control system data acquisition function  

NASA Astrophysics Data System (ADS)

A functional description of the various levels of the SSF power management and distribution dc test-bed control system architecture is presented, and the data acquisition function and the status of its implementation are described. The data requirements for the test-bed control system are dictated by the functionality being implemented at each level of the architecture. The test-bed control system hierarchy data acquisition function is distributed among its various levels. Fast-acting control functions that require time critical data are implemented at the lowest level. These functions require periodic data sampling to assure safe system operation and performance. Slower response control functions are implemented at the higher levels and require data to be reported at least every second. The present data acquisition function meets the requirements for a hierarchical and distributed power management and control system.

Baez, Anastacio N.; Mackin, Michael; Wright, Theodore

309

Impact of quasi-dc currents on three-phase distribution transformer installations. Power Systems Technology Program  

SciTech Connect

This report summarizes a series of tests designed to determine the response of quasi-dc currents on three-phase power distribution transformers for electric power systems. In general, if the dc injection is limited to the primary side of a step-down transformer, significant harmonic distortion is noted and an increase in the reactive power demand results. For dc injection on the secondary (load) side of the step-down transformer the harmonic content at the secondary side is quite high and saturation occurs with a relatively low level of dc injection; however, the reactive power demand is significantly lower. These tests produced no apparent damage to the transformers. Transformer damage is dependent on the duration of the dc excitation, the level of the excitation, and on thermal characteristics of the transfer. The transformer response time is found to be much shorter than seen in power transformer tests at lower dc injection levels. This shorter response time suggests that the response time is strongly dependent on the injected current levels, and that higher levels of dc injection for shorter durations could produce very high reactive power demands and harmonic distortion within a few tenths of a second. The added reactive power load could result in the blowing of fuses on the primary side of the transformer for even moderate dc injection levels, and neutral currents are quite large under even low-level dc injection. This ``smoking neutral`` results in high-level harmonic injection into equipment via the neutral and in possible equipment failure.

McConnell, B.W.; Barnes, P.R. [Oak Ridge National Lab., TN (United States); Tesche, F.M. [Tesche (F.M.), Dallas, TX (United States); Schafer, D.A. [Mission Research Corp., Albuquerque, NM (United States)

1992-06-01

310

A COAXIAL TE011 CAVITY AND A SYSTEM TO MEASURE DC AND RF PROPERTIES OF SUPERCONDUCTORS  

SciTech Connect

A coaxial niobium cavity has been designed and built where the center conductor consists of a removable sample. In addition, a system to measure properties such as magnetization, penetration depth, critical temperature and thermal conductivity on the same cylindrical sample has been designed and built. The purpose of this effort is to investigate possible correlations between DC and RF properties of superconductors. In this contribution, the design of the various components is discussed and the test results on a niobium sample obtained so far are presented.

Gianluigi Ciovati; Peter Kneisel; Ganapati Myneni; Larry Turlington; Gary Slack; Michael Morrone; William Clemens; Richard Bundy; Thomas Elliott; Jayanta Mondal

2008-01-23

311

Analysis of system wide distortion in an integrated power system utilizing a high voltage DC bus and silicon carbide power devices  

E-print Network

This research investigates the distortion on the electrical distribution system for a high voltage DC Integrated Power System (IPS). The analysis was concentrated on the power supplied to a propulsion motor driven by an ...

Fallier, William F. (William Frederick)

2007-01-01

312

Residential Wiring.  

ERIC Educational Resources Information Center

The second in a series of three curriculum packages on wiring, these materials for a five-unit course were developed to prepare postsecondary students for entry-level employment in the residential wiring trade. The five units are: (1) blueprint reading and load calculations; (2) rough-in; (3) service; (4) trim out and troubleshooting; and (5) load…

Taylor, Mark

313

Wire chamber  

DOEpatents

A wire chamber or proportional counter device, such as Geiger-Mueller tube or drift chamber, improved with a gas mixture providing a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor.

Atac, Muzaffer (Wheaton, IL)

1989-01-01

314

Study of a guarded electrode system in the dc conductivity measurement of insulating liquid  

NASA Astrophysics Data System (ADS)

The design and choice of an electrode system is important in dc conductivity measurement of insulating liquid. In this paper, the electric field distribution of an electrode system which consists of two parallel circular metallic electrodes and a guard electrode has been studied using Comsol Multiphysics software. A new parameter, which is not yet involved in current standards, the edge radius, has been mentioned in the literature formerly and is currently discussed in a CIGRE working group. In this paper, the influence of this parameter has been investigated by means of field calculation. As seen from the simulating result, there are regions in the vicinity of the edges of the guard and measuring electrode that are under high electric field. If the edges of these two electrodes are sharp, the maximum electric field in the test cell will be much higher than the average field between the measuring electrode and the high voltage electrode. An empirical equation has been proposed to calculate this maximum field. The classic correction expression for an effective radius has been re-evaluated with the edge radius being taken into account. Experimental work has been performed to confirm this conclusion. Three kinds of mineral oils with different ageing times have been tested under the dc field using a guarded electrode system and the electric strengths of these oils have been estimated. A recommendation has been made to current standards in insulating liquid measurement.

Zhou, Yuan; Hao, Miao; Chen, George; Wilson, Gordon; Jarman, Paul

2014-07-01

315

Three dimensional finite element methods: Their role in the design of DC accelerator systems  

SciTech Connect

High Voltage Engineering has designed, built and tested a 2 MV dual irradiation system that will be applied for radiation damage studies and ion beam material modification. The system consists of two independent accelerators which support simultaneous proton and electron irradiation (energy range 100 keV - 2 MeV) of target sizes of up to 300 Multiplication-Sign 300 mm{sup 2}. Three dimensional finite element methods were used in the design of various parts of the system. The electrostatic solver was used to quantify essential parameters of the solid-state power supply generating the DC high voltage. The magnetostatic solver and ray tracing were used to optimize the electron/ion beam transport. Close agreement between design and measurements of the accelerator characteristics as well as beam performance indicate the usefulness of three dimensional finite element methods during accelerator system design.

Podaru, Nicolae C.; Gottdang, A.; Mous, D. J. W. [High Voltage Engineering Europa B.V., P.O. Box 99, 3800 AB, Amersfoort (Netherlands)

2013-04-19

316

A Kalman filtering based control scheme for the improvement of dynamic performance of an AC/DC power system  

NASA Astrophysics Data System (ADS)

In this dissertation, two major accomplishments are achieved. First, the feasibility of a proposed Wyoming to California HVDC system having the ratings of 1000 MW, ±500 kV, 2 kA, 860 miles and 12-pulse bipolar lines is shown for exporting Wyoming's electrical power resources to the heavy loaded western states. The second and the main objective of this dissertation is the development of a Kalman filtering (KF) based control scheme applied to an ac/dc power system. It is shown that the use KF algorithm to estimate some of the system states and utilizing them in a proportional Integral (PI) controller which has a better performance for this specific control scheme have resulted in a better dynamic performance of the proposed system. A set of case studies has shown that the system dynamic performance is improved for most of the contingencies. Ac and dc noisy voltage and current measurements received from the simulated ac/dc power system are sent to the KF estimation algorithm. The noise-separated best estimates of measurable states are computed and sent to a PI controller-based current and firing angle control subsections in order to provide a set of optimum thyristor firing angles for both converter stations during and after contingencies until the normal operation is reached. To evaluate the dynamic performance of the system with the KF algorithm, the model is simulated by a well-known digital simulation package, Electromagnetic Transients DC Program (PSCAD/EMTDC) of Manitoba HVDC Research Center. To apply the KF algorithm, a general, linearized, state-space model of the proposed ac/dc system, appropriate for analyzing both the KF and the electromagnetics transients, is derived first. The derived model enables the representation of an ac power system with two ac sources and one HVDC line with a parallel ac line connecting the two systems. It is shown that system eigenvalues of the discretized system model for a normal operating point are inside the unit circle that enables a stable operation. It is also shown that the system is controllable and observable for that specific point. The severity of a three-phase short circuit in the proposed ac/dc system is greatly reduced due to the HVDC link. One of the aims of this dissertation was to show that the addition of a parallel dc tie into an existing ac line resulted in dynamic performance improvement of the entire ac system, particularly during and after contingencies. It is also shown that a combination of the KF algorithm and PI control provides a stable recovery of the ac/dc system after a set of contingencies.

Pecen, Recayi

317

Development of the electronic control unit for the rack-actuating steer-by-wire using the hardware-in-the-loop simulation system  

Microsoft Academic Search

The steer-by-wire (SBW) system in a passenger car substitutes the typical mechanical linkage between the steering wheel and the front wheel with electric wires. The control conception of the rack-actuating SBW system was proposed in this paper. Basically, the controller should compensate for a conventional steering system composed of mechanical linkages. The hardware-in-the-loop-simulation (HILS) system was developed for the electronic

Tong-Jin Park; Chang-Soo Han; Sang-Ho Lee

2005-01-01

318

Design of a hybrid (wired/wireless) acquisition data system for monitoring of cultural heritage physical parameters in smart cities.  

PubMed

Preventive conservation represents a working method and combination of techniques which helps in determining and controlling the deterioration process of cultural heritage in order to take the necessary actions before it occurs. It is acknowledged as important, both in terms of preserving and also reducing the cost of future conservation measures. Therefore, long-term monitoring of physical parameters influencing cultural heritage is necessary. In the context of Smart Cities, monitoring of cultural heritage is of interest in order to perform future comparative studies and load information into the cloud that will be useful for the conservation of other heritage sites. In this paper the development of an economical and appropriate acquisition data system combining wired and wireless communication, as well as third party hardware for increased versatility, is presented. The device allows monitoring a complex network of points with high sampling frequency, with wired sensors in a 1-wire bus and a wireless centralized system recording data for monitoring of physical parameters, as well as the future possibility of attaching an alarm system or sending data over the Internet. This has been possible with the development of three board's designs and more than 5000 algorithm lines. System tests have shown an adequate system operation. PMID:25815447

Diego, Fernando-Juan García; Esteban, Borja; Merello, Paloma

2015-01-01

319

Performance analysis of radiation cooled dc transmission lines for high power space systems  

NASA Technical Reports Server (NTRS)

As space power levels increase to meet mission objectives and also as the transmission distance between power source and load increases, the mass, volume, power loss, and operating voltage and temperature become important system design considerations. This analysis develops the dependence of the specific mass and percent power loss on hte power and voltage levels, transmission distance, operating temperature and conductor material properties. Only radiation cooling is considered since the transmission line is assumed to operate in a space environment. The results show that the limiting conditions for achieving low specific mass, percent power loss, and volume for a space-type dc transmission line are the permissible transmission voltage and operating temperature. Other means to achieve low specific mass include the judicious choice of conductor materials. The results of this analysis should be immediately applicable to power system trade-off studies including comparisons with ac transmission systems.

Schwarze, G. E.

1985-01-01

320

Investigation of the effects of laser non-linearity and RIN in direct modulation hybrid wired/wireless PON systems employing an integrated two section laser  

NASA Astrophysics Data System (ADS)

In this paper the transmission of OFDM based wired/wireless services for hybrid PONs using direct laser modulation is studied. To overcome the limitations imposed by direct modulation of cost effective low bandwidth laser transmitters, we make use of novel monolithically integrated Discrete Mode lasers and optical injection. The system includes a wired OFDM signal, operating at 12.5 Gb/s and three wireless signals delivering Long Term Evolution (LTE) services encoded with 16 QAM. The system's performance is evaluated for various relative power ratios of the wired/wireless signals. Additionally, the impact of Relative Intensity Noise (RIN) on such a hybrid system is studied through computer simulations.

Saljoghei, Arsalan; Browning, Colm; Smyth, Frank; Barry, Liam P.

2015-03-01

321

An EMTP system level model of the PMAD DC test bed  

NASA Technical Reports Server (NTRS)

A power management and distribution direct current (PMAD DC) test bed was set up at the NASA Lewis Research Center to investigate Space Station Freedom Electric Power Systems issues. Efficiency of test bed operation significantly improves with a computer simulation model of the test bed as an adjunct tool of investigation. Such a model is developed using the Electromagnetic Transients Program (EMTP) and is available to the test bed developers and experimenters. The computer model is assembled on a modular basis. Device models of different types can be incorporated into the system model with only a few lines of code. A library of the various model types is created for this purpose. Simulation results and corresponding test bed results are presented to demonstrate model validity.

Dravid, Narayan V.; Kacpura, Thomas J.; Tam, Kwa-Sur

1991-01-01

322

An EMTP system level model of the PMAD DC test bed  

NASA Technical Reports Server (NTRS)

A power management and distribution direct current (PMAD DC) test bed was set up at the NASA Lewis Research Center to investigate Space Station Freedom Eelectric Power Systems issues. Efficiency of test bed operation significantly improves with a computer simulation model of the test bed as an adjunct tool of investigation. Such a model is developed using the Electromagnetic Transients Program (EMTP) and is available to the test bed developers and experimenters. The computer model is assembled on a modular basis. Device models of different types can be incorporated into the system model with only a few lines of code. A library of the various model types is created for this purpose. Simulation results and corresponding test bed results are presented to demonstrate model validity.

Dravid, Narayan V.; Kacpura, Thomas J.; Tam, Kwa-Sur

1991-01-01

323

Wire Wise.  

ERIC Educational Resources Information Center

Discusses how today's technology is encouraging schools to invest in furnishings that are adaptable to computer use and telecommunications access. Explores issues concerning modularity, wiring management, ergonomics, durability, price, and aesthetics. (GR)

Swanquist, Barry

1998-01-01

324

UN Wire  

NSDL National Science Digital Library

Provided by the UN Foundation, UN Wire is a new "daily news summary covering the United Nations, global affairs and key international issues." Users interested in the UN or global affairs will find UN Wire an excellent resource for quick, concise accounts of the day's major stories. Each day, UN Wire covers issues such as UN Affairs; Health; Women, Children, and Population; Environment; Trade; Humanitarian Aid; Human Rights; and Peacekeeping. Typical entries include a few short paragraphs and direct links to the original news source and/or related resources. Free registration is required and users can subscribe for free daily email summaries of the headlines. UN Wire should be available for email delivery in complete form in the next few months.

1999-01-01

325

Stretching Wires  

NSDL National Science Digital Library

In this activity, learners determine the elastic and plastic properties of different types of metal wires. Learners discover that wires of the same gauge, but made of different metals, typically support different loads (masses) before going through the elastic to plastic transition. Learners also learn the difference between elastic deformation, which is recoverable after the load is removed, and plastic deformation, which is not recoverable. Note: one way to save time on this lab is to have different groups test different metals.

2013-01-04

326

Superconductivity for Electric Systems Annual Peer Review Washington, DC July 27-29, 2004 University of Wisconsin-Madison  

E-print Network

1 Superconductivity for Electric Systems Annual Peer Review Washington, DC July 27-29, 2004. Gurevich, D. C. Larbalestier Industrial partner: American Superconductor Corporation Funding: ORNL: 225 k$ (DOE) LANL: 200 k$ (DOE) UW: 200 k$ (DOE, AFOSR-MURI) #12;2 Superconductivity for Electric Systems

327

An Analytical Design Method for a Regenerative Braking Control System for DC-electrified Railway Systems under Light Load Conditions  

NASA Astrophysics Data System (ADS)

A DC-electrified railway system that is fed by diode rectifiers at a substation is unable to return the electric power to an AC grid. Accordingly, the braking cars have to restrict regenerative braking power when the power consumption of the powering cars is not sufficient. However, the characteristics of a DC-electrified railway system, including the powering cars, is not known, and a mathematical model for designing a controller has not been established yet. Hence, the object of this study is to obtain the mathematical model for an analytical design method of the regenerative braking control system. In the first part of this paper, the static characteristics of this system are presented to show the position of the equilibrium point. The linearization of this system at the equilibrium point is then performed to describe the dynamic characteristics of the system. An analytical design method is then proposed on the basis of these characteristics. The proposed design method is verified by experimental tests with a 1kW class miniature model, and numerical simulations.

Saito, Tatsuhito; Kondo, Keiichiro; Koseki, Takafumi

328

An Advanced Fly-By-Wire Flight Control System for the RASCAL Research Rotorcraft: Concept to Reality  

NASA Technical Reports Server (NTRS)

Design features of a new fly-by-wire flight control system for the Rotorcraft-Aircrew Systems Concepts Airborne Laboratory (RASCAL) are described. Using a UH-60A Black Hawk helicopter as a baseline vehicle, the RASCAL will be a flying laboratory capable of supporting the research requirements of major NASA and Army guidance, control, and display research programs. The paper describes the research facility requirements of these pro-rams and the design implementation of the research flight control system (RFCS), with emphasis on safety-of-flight, adaptability to multiple requirements and performance considerations.

Rediess, Nicholas A.; Dones, Fernando; McManus, Bruce L.; Ulmer, Lon; Aiken, Edwin W. (Technical Monitor)

1995-01-01

329

Energy efficiency improvement in ac\\/dc\\/ac diode-clamped multilevel conversion systems  

Microsoft Academic Search

An analysis of the efficiency of AC\\/DC\\/AC diode-clamped multilevel converters is presented, where commanded and suitable variations of the DC-link voltages are proposed in order to decrease the energy losses. The study is carried out also aiming at the correct DC-link capacitor voltage balance, obtained with additional chopper stages together with a new PWM technique, considering both inverter and line-side

G. Borghetti; M. Carpaneto; M. Marchesoni; P. Tenca; L. Vaccaro

2008-01-01

330

Design of feedback laws for dc-to-ac conversion in photovoltaic systems  

Microsoft Academic Search

One-phase dc-ac stand-alone conversion for a photovoltaic standard panel is analyzed in this paper. A modular structure consisting of the cascade connection of a voltage step-up dc-to-dc switching converter with galvanic isolation and a buck converter-based inverter stage is proposed. Different feedback laws for the inverter stage are investigated to guarantee output voltage regulation. A comparative analysis of the modular

Angel Cid-Pastor; Corinne Alonso; Jose F. Cugat-Curto; Bruno Estibals; Luis Martinez-Salamero

2004-01-01

331

Transient current pulses in rocket-extended wires used to trigger lightning  

NASA Astrophysics Data System (ADS)

We analyze current, electric field, and optical signatures of the sudden electrical breakdown processes (precursors) that occur at the top of the upward extending, grounded, Kevlar-covered copper wires used to artificially trigger lightning. For one launch, before the sustained upward positive leader initiated, we estimate that up to 10,000 precursors occurred (one every few hundred microseconds) with peak currents from 1 to more than 100 A. Luminosity at the wire tip was observed for 339 of 410 precursors examined in detail and, in seven cases, discharge channels developed to lengths of 3 to 8 m over times of several hundred microseconds. The measured propagation speeds of current pulses on the triggering wires were less than the speed of light, and decreased from about 2.8 × 108 m s-1 to about 2.3 × 108 m s-1with increasing wire-top heights from about 80 m to about 340 m. The triggering wire and its grounding system are modeled as uniform transmission lines with model predictions that are consistent with the measured wire-base precursor current signatures. The modeling shows that (1) the characteristic impedance of the triggering wire, the ratio of the propagating precursor voltage pulse to its associated current pulse, is between 600 and 800 ?; (2) the 25 m ground rod grounding impedance for the peak precursor current is about 100 ?, while the DC grounding resistance is 20 ?; and (3) the current reflection coefficient at ground for peak precursor current is ˜0.9.

Biagi, C. J.; Uman, M. A.; Hill, J. D.; Rakov, V. A.; Jordan, D. M.

2012-04-01

332

Accuracy improvement of wire-EDM by real-time wire tension control  

Microsoft Academic Search

In this paper, a closed-loop wire tension control system for a wire-EDM machine is presented to improve the machining accuracy. Dynamic models of the wire feed control apparatus and wire tension control apparatus are derived to analyze and design the control system. PI controller and one-step-ahead adaptive controller are employed to investigate the dynamic performance of the closed-loop wire tension

Mu-Tian Yan; Pin-Hsum Huang

2004-01-01

333

Early Oscillation Detection for DC/DC Converter Fault Diagnosis  

NASA Technical Reports Server (NTRS)

The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.

Wang, Bright L.

2011-01-01

334

Synergetic aspects of gas-discharge: lateral patterns in dc systems with a high ohmic barrier  

NASA Astrophysics Data System (ADS)

The understanding of self-organized patterns in spatially extended nonlinear dissipative systems is one of the most challenging subjects in modern natural sciences. Such patterns are also referred to as dissipative structures. We review this phenomenon in planar low temperature dc gas-discharge devices with a high ohmic barrier. It is demonstrated that for these systems a deep qualitative understanding of dissipative structures can be obtained from the point of view of synergetics. At the same time, a major contribution can be made to the general understanding of dissipative structures. The discharge spaces of the experimentally investigated systems, to good approximation, have translational and rotational symmetry by contraction. Nevertheless, a given system may exhibit stable current density distributions and related patterns that break these symmetries. Among the experimentally observed fundamental patterns one finds homogeneous isotropic states, fronts, periodic patterns, labyrinth structures, rotating spirals, target patterns and localized filaments. In addition, structures are observed that have the former as elementary building blocks. Finally, defect structures as well as irregular patterns are common phenomena. Such structures have been detected in numerous other driven nonlinear dissipative systems, as there are ac gas-discharge devices, semiconductors, chemical solutions, electrical networks and biological systems. Therefore, from the experimental observations it is concluded that the patterns in planar low temperature dc gas-discharge devices exhibit universal behavior. From the theoretical point of view, dissipative structures of the aforementioned kind are also referred to as attractors. The possible sets of attractors are an important characteristic of the system. The number and/or qualitative nature of attractors may change when changing parameters. The related bifurcation behavior is a central issue of the synergetic approach chosen in the present article. A short review of possible theoretical approaches reveals that a theoretical description of the experimentally observed patterns is far from being satisfactory. Bearing this in mind, a qualitative model of the reaction-diffusion type is considered. Surprisingly enough, this model allows for a qualitative description of almost all fundamental patterns that have been observed experimentally. Also, so far the predictive power of this model is unmatched.

Purwins, H.-G.; Stollenwerk, L.

2014-12-01

335

Corner error simulation of rough cutting in wire EDM  

Microsoft Academic Search

This paper describes a novel simulation method for wire electrical discharge machining (EDM) in corner cut of rough cutting. In the simulation system, we analyzed the wire electrode vibration due to the reaction force acting on the wire electrode during the wire EDM, set up a geometrical model between the wire electrode path and NC path, and investigated the relationship

Fuzhu Han; Jie Zhang; Isago Soichiro

2007-01-01

336

Composite superconducting wires obtained by high-rate tinning in molten Bi-Pb-Sr-Ca-Cu-O system  

NASA Technical Reports Server (NTRS)

Long lengths of metal superconductor composites were prepared by passing a copper wire through the bismuth based molten oxide system at a constant speed. The key to successful composite preparation is the high pulling speed involved, which permits minimization of the severe interaction between the unbuffered metal surface and the oxide melt. Depending on the temperature of the melt and the pulling speed, a coating with different thickness and microstructure appeared. The nonannealed thick coatings contained a Bi2(Sr,Ca)2Cu1O6 phase as a major component. After relatively short time annealing at 800 C, both resistivity and initial magnetization versus temperature measurements show superconducting transitions beginning in the 110 to 115 K region. The effects of annealing and composition on obtained results are discussed. This method of manufacture led to the fabrication of wire with a copper core in a dense covering with uniform thickness of about h approximately equal to 5 to 50 microns. Composite wires with h approximately equal to 10 microns (h/d approximately equal to 0.1) sustained bending on a 15 mm radius frame without cracking during flexing.

Grosav, A. D.; Konopko, L. A.; Leporda, N. I.

1991-01-01

337

Dynamical Symmetry Breaking as the Origin of the Zero-dc-Resistance State in an ac-Driven System  

NASA Astrophysics Data System (ADS)

Under a strong ac drive the zero-frequency linear response dissipative resistivity ?d(j=0) of a homogeneous state is allowed to become negative. We show that such a state is absolutely unstable. The only time-independent state of a system with a ?d(j=0)<0 is characterized by a current which almost everywhere has a magnitude j0 fixed by the condition that the nonlinear dissipative resistivity ?d(j20)=0. As a result, the dissipative component of the dc-electric field vanishes. The total current may be varied by rearranging the current pattern appropriately with the dissipative component of the dc-electric field remaining zero. This result, together with the calculation of Durst et al., indicating the existence of regimes of applied ac microwave field and dc magnetic field where ?d(j=0)<0, explains the zero-resistance state observed by Mani et al. and Zudov et al..

Andreev, A. V.; Aleiner, I. L.; Millis, A. J.

2003-08-01

338

Cyclotron-resonance-induced negative dc conductivity in a two-dimensional electron system on liquid helium  

NASA Astrophysics Data System (ADS)

We theoretically predict instability of a zero-dc-current state of the two-dimensional electron system formed on the surface of liquid helium induced by the cyclotron resonance (CR). This conclusion follows from the theoretical analysis of the dc magnetoconductivity which takes into account the contribution from radiation in an exact way. A many-electron model of the dynamic structure factor of the 2D Coulomb liquid is used to describe the influence of strong internal forces acting between electrons. For low electron densities and high amplitudes of the microwave field, the dc magnetoconductivity is shown to become negative in the vicinity of the CR which causes the instability. This effect is strongly suppressed by Coulomb forces in the region of high densities.

Monarkha, Yu. P.

2015-03-01

339

Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites  

NASA Technical Reports Server (NTRS)

An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

2000-01-01

340

Lowest of AC-DC power output for electrostrictive polymers energy harvesting systems  

NASA Astrophysics Data System (ADS)

Advances in technology led to the development of electronic circuits and sensors with extremely low electricity consumption. At the same time, structural health monitoring, technology and intelligent integrated systems created a need for wireless sensors in hard to reach places in aerospace vehicles and large civil engineering structures. Powering sensors with energy harvesters eliminates the need to replace batteries on a regular basis. Scientists have been forced to search for new power source that are able to harvested energy from their surrounding environment (sunlight, temperature gradients etc.). Electrostrictive polymer belonging to the family of electro-active polymers, offer unique properties for the electromechanical transducer technology has been of particular interest over the last few years in order to replace conventional techniques such as those based on piezoelectric or electromagnetic, these materials are highly attractive for their low-density, with large strain capability that can be as high as two orders of magnitude greater than the striction-limited, rigid and fragile electroactive ceramics. Electrostrictive polymers sensors respond to vibration with an ac output signal, one of the most important objectives of the electronic interface is to realize the required AC-DC conversion. The goal of this paper is to design an active, high efficiency power doubler converter for electrostrictive polymers exclusively uses a fraction of the harvested energy to supply its active devices. The simulation results show that it is possible to obtain a maximum efficiency of the AC-DC converter equal to 80%. Premiliminary experimental measurements were performed and the results obtained are in good agreement with simulations.

Meddad, Mounir; Eddiai, Adil; Hajjaji, Abdelowahed; Guyomar, Daniel; Belkhiat, Saad; Boughaleb, Yahia; Chérif, Aida

2013-11-01

341

Grid-connected PV-wind-fuel cell hybrid system employing a supercapacitor bank as storage device to supply a critical DC load  

Microsoft Academic Search

In this work a grid-connected renewable energy system composed by a 1kW photovoltaic (PV) array and a 1 kW wind turbine (WT) is presented. The generated power from each renewable source is processed by independent dc-dc converters and provided to a common dc bus. Once batteries employment is not desired, a 1.2 kW fuel cell (FC) and a supercapacitor bank

Roberto Francisco Coelho; Lenon Schimtz; Denizar Cruz Martins

2011-01-01

342

University Wire  

NSDL National Science Digital Library

University Wire is a daily Internet news service for college newspapers. Included are a story of the day, a large list of pointers to Internet resources in topics such as current headlines, politics, medicine and health, and women's resources; a "Kopyedit Korner," with pointers to writing reference materials; a placement center with job openings lists for college journalists; a large selection of pointers to college newspapers; and pointers to general circulation newspapers. Pointers to student and professional journalism organizations, as well as a calendar of journalism related events, are also provided. University Wire is a service of The Main Quad.

343

Tap-Off Power From the Overhead Shield Wires of an HV Transmission Line  

Microsoft Academic Search

In recent years, there was an increase of ancillary service loads, such as signaling systems, inspection robots, surveillance cameras, and other monitoring devices distributed along high-voltage transmission lines which require low-power dc voltage supplies. This paper investigates the use of the induced voltage in the shield wires of an overhead 525 kV transmission line as a primary power source. Since

Ricardo Leon Vasquez-Arnez; Mario Masuda; José Antonio Jardini; Walter Kaiser; Erni José Vitório Nicodem

2012-01-01

344

Characteristics of the multiple-input DC-DC converter  

Microsoft Academic Search

In the zero-emission electric power generation system, a multiple-input DC-DC converter is useful to obtain the regulated output voltage from several input power sources such as a solar array, wind generator, fuel cell, and so forth. A new multiple-input DC-DC converter is proposed and analyzed. As a result, the static and dynamic characteristics are clarified theoretically, and the results are

Hirofumi Matsuo; Wenzhong Lin; Fujio Kurokawa; Tetsuro Shigemizu; Nobuya Watanabe

2004-01-01

345

DC Circuit Powered by Orbital Motion: Magnetic Interactions in Compact Object Binaries and Exoplanetary Systems  

NASA Astrophysics Data System (ADS)

The unipolar induction DC circuit model, originally developed by Goldreich and Lynden-Bell for the Jupiter-Io system, has been applied to different types of binary systems in recent years. We show that there exists an upper limit to the magnetic interaction torque and energy dissipation rate in such a model. This arises because when the resistance of the circuit is too small, the large current flow severely twists the magnetic flux tube connecting the two binary components, leading to the breakdown of the circuit. Applying this limit, we find that in coalescing neutron star binaries, magnetic interactions produce negligible correction to the phase evolution of the gravitational waveform, even for magnetar-like field strengths. However, energy dissipation in the binary magnetosphere may still give rise to electromagnetic radiation prior to the final merger. For ultracompact white dwarf binaries, we find that unipolar induction does not provide adequate energy dissipation to explain the observed X-ray luminosities of several sources. For exoplanetary systems containing close-in Jupiters or super-Earths, the magnetic torque and energy dissipation induced by the orbital motion are negligible, except possibly during the early T Tauri phase, when the stellar magnetic field is stronger than 103 G.

Lai, Dong

2012-09-01

346

DC CIRCUIT POWERED BY ORBITAL MOTION: MAGNETIC INTERACTIONS IN COMPACT OBJECT BINARIES AND EXOPLANETARY SYSTEMS  

SciTech Connect

The unipolar induction DC circuit model, originally developed by Goldreich and Lynden-Bell for the Jupiter-Io system, has been applied to different types of binary systems in recent years. We show that there exists an upper limit to the magnetic interaction torque and energy dissipation rate in such a model. This arises because when the resistance of the circuit is too small, the large current flow severely twists the magnetic flux tube connecting the two binary components, leading to the breakdown of the circuit. Applying this limit, we find that in coalescing neutron star binaries, magnetic interactions produce negligible correction to the phase evolution of the gravitational waveform, even for magnetar-like field strengths. However, energy dissipation in the binary magnetosphere may still give rise to electromagnetic radiation prior to the final merger. For ultracompact white dwarf binaries, we find that unipolar induction does not provide adequate energy dissipation to explain the observed X-ray luminosities of several sources. For exoplanetary systems containing close-in Jupiters or super-Earths, the magnetic torque and energy dissipation induced by the orbital motion are negligible, except possibly during the early T Tauri phase, when the stellar magnetic field is stronger than 10{sup 3} G.

Lai Dong [Department of Astronomy, Cornell University, Ithaca, NY 14850 (United States)

2012-09-20

347

47 CFR 32.2431 - Aerial wire.  

Code of Federal Regulations, 2014 CFR

...CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions for Balance Sheet Accounts § 32.2431 Aerial wire. (a) This account shall include the original cost of bare line wire and other...

2014-10-01

348

Clinical percutaneous imaging of coronary anatomy using an over-the-wire ultrasound catheter system  

Microsoft Academic Search

This manuscript describes initial applications of a unique new intravascular ultrasound imaging catheter. This 5.5F catheter uses an over-the-wire design and incorporates a phased array transducer at its tip. There are no moving parts. A 360° image is produced perpendicular to the catheter axis using a 20 MHz center frequency. A dedicated minicomputer is used for initial image processing, as

J. B. Hodgson; S. P. Graham; A. D. Savakus; S. G. Dame; D. N. Stephens; P. S. Dhillon; D. Brands; H. Sheehan; M. J. Eberle

1989-01-01

349

Novel Three-Component Rieske Non-Heme Iron Oxygenase System Catalyzing the N-Dealkylation of Chloroacetanilide Herbicides in Sphingomonads DC-6 and DC-2  

PubMed Central

Sphingomonads DC-6 and DC-2 degrade the chloroacetanilide herbicides alachlor, acetochlor, and butachlor via N-dealkylation. In this study, we report a three-component Rieske non-heme iron oxygenase (RHO) system catalyzing the N-dealkylation of these herbicides. The oxygenase component gene cndA is located in a transposable element that is highly conserved in the two strains. CndA shares 24 to 42% amino acid sequence identities with the oxygenase components of some RHOs that catalyze N- or O-demethylation. Two putative [2Fe-2S] ferredoxin genes and one glutathione reductase (GR)-type reductase gene were retrieved from the genome of each strain. These genes were not located in the immediate vicinity of cndA. The four ferredoxins share 64 to 72% amino acid sequence identities to the ferredoxin component of dicamba O-demethylase (DMO), and the two reductases share 62 to 65% amino acid sequence identities to the reductase component of DMO. cndA, the four ferredoxin genes, and the two reductases genes were expressed in Escherichia coli, and the recombinant proteins were purified using Ni-affinity chromatography. The individual components or the components in pairs displayed no activity; the enzyme mixture showed N-dealkylase activities toward alachlor, acetochlor, and butachlor only when CndA-His6 was combined with one of the four ferredoxins and one of the two reductases, suggesting that the enzyme consists of three components, a homo-oligomer oxygenase, a [2Fe-2S] ferredoxin, and a GR-type reductase, and CndA has a low specificity for the electron transport component (ETC). The N-dealkylase utilizes NADH, but not NADPH, as the electron donor. PMID:24928877

Chen, Qing; Wang, Cheng-Hong; Deng, Shi-Kai; Wu, Ya-Dong; Li, Yi; Yao, Li; Jiang, Jian-Dong; Yan, Xin; Li, Shun-Peng

2014-01-01

350

A Stability and Tansparency Analysis of Steer-by-Wire System Based on the Bilateral Control and Dual-Port Network Theory  

Microsoft Academic Search

Compared with mechanical steering system, hydraulic steering system and electric power assisted system, Steer By Wire (SBW) system has the advantage of variable steering ratio, easy assembling and enhancement of active safety, etc.. Due to only electric link but no mechanical link between steering wheel and front wheel, the force between front wheel and steering wheel, which is of great

Liu Zhao; Peng Wei Ping

2010-01-01

351

Aircraft wiring program status report  

NASA Astrophysics Data System (ADS)

In this Naval Air Warfare Center (NAWC) Aircraft Division status report, the general and wire and cable component activities, the systems engineering activities, the aircraft wiring lead maintenance activities, the NAVAIR/NASA interface activities, and the Base Realignment and Closure (BRAC) Commission recommendations are presented.

Beach, Rex

1995-11-01

352

System Identification of a DC Motor Using Different Variants of Particle Swarm Optimization Technique  

NASA Astrophysics Data System (ADS)

System identification is a ubiquitous necessity for successful applications in various fields. The area of system identification can be characterized by a small number of leading principles, e.g. to look for sustainable descriptions by proper decisions in the triangle of model complexity, information contents in the data, and effective validation. Particle Swarm Optimization (PSO) is a stochastic, population-based optimization algorithm and many variants of PSO have been developed since, including constrained, multi objective, and discrete or combinatorial versions and applications have been developed using PSO in many fields. The basic PSO algorithm implicitly utilizes a fully connected neighborhood topology. However, local neighborhood models have also been proposed for PSO long ago, where each particle has access to the information corresponding to its immediate neighbors, according to a certain swarm topology. In this local neighborhood model of PSO, particles have information only of their own and their nearest neighbors' bests, rather than that of the entire population of the swarm. In the present work basic PSO method and two of its local neighborhood variants are utilized for determining the optimal parameters of a dc motor. The result obtain from the simulation study demonstrate the usefulness of the proposed methodology.

Kar, Subhajit; Sharma, Kaushik Das

2010-10-01

353

Modeling and simulation of a DC motor control system with digital PID controller and encoder in FPGA using Xilinx system generator  

Microsoft Academic Search

This paper presents a novel method for design and simulation of a DC motor closed loop control system in Field Programmable Gate Array device (FPGA). The digital designed PID controller is more advanced, beneficial and therefore produces a better response, as compared to the analog PID with velocity measurement. It can be implemented on system-on-chip devices easily. MATLAB Xilinx system

Behzad Behnam; Masoud Mansouryar

2011-01-01

354

47 CFR 68.215 - Installation of other than “fully protected” system premises wiring that serves more than four...  

Code of Federal Regulations, 2012 CFR

...accordingly in specific installations where ambient temperatures are in excess of 25 °C: Maximum Continuous Current Capacity of PVC Insulated Copper Wire, Confined Wire size, AWG Circular mils Maximum current, amperes 32 63.2 0.32 30...

2012-10-01

355

47 CFR 68.215 - Installation of other than “fully protected” system premises wiring that serves more than four...  

Code of Federal Regulations, 2013 CFR

...accordingly in specific installations where ambient temperatures are in excess of 25 °C: Maximum Continuous Current Capacity of PVC Insulated Copper Wire, Confined Wire size, AWG Circular mils Maximum current, amperes 32 63.2 0.32 30...

2013-10-01

356

47 CFR 68.215 - Installation of other than “fully protected” system premises wiring that serves more than four...  

Code of Federal Regulations, 2010 CFR

...accordingly in specific installations where ambient temperatures are in excess of 25 °C: Maximum Continuous Current Capacity of PVC Insulated Copper Wire, Confined Wire size, AWG Circular mils Maximum current, amperes 32 63.2 0.32 30...

2010-10-01

357

47 CFR 68.215 - Installation of other than “fully protected” system premises wiring that serves more than four...  

Code of Federal Regulations, 2014 CFR

...accordingly in specific installations where ambient temperatures are in excess of 25 °C: Maximum Continuous Current Capacity of PVC Insulated Copper Wire, Confined Wire size, AWG Circular mils Maximum current, amperes 32 63.2 0.32 30...

2014-10-01

358

47 CFR 68.215 - Installation of other than “fully protected” system premises wiring that serves more than four...  

Code of Federal Regulations, 2011 CFR

...accordingly in specific installations where ambient temperatures are in excess of 25 °C: Maximum Continuous Current Capacity of PVC Insulated Copper Wire, Confined Wire size, AWG Circular mils Maximum current, amperes 32 63.2 0.32 30...

2011-10-01

359

1392 IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS, VOL. 25, NO. 7, JULY 2006 Efficient DC Fault Simulation of Nonlinear Analog  

E-print Network

@ee.washington.edu). M. W. Tian is with Cadence Design Systems, San Jose, CA 95134 USA. G. Shi was with the Department methods of analog testing, dc testing is generally cheaper since it does not require expensive test and practically important problem. In general, dc simulation of nonlinear analog circuits amounts to solving a set

Shi, C.-J. Richard

360

DC Machine  

NSDL National Science Digital Library

The effect of the commutator is to produce a fixed spatial distribution of current directions in the armature conductors (shown as blue & green circles) independent of shaft rotation. The field created by these currents (armature reaction) is vertically directed along the quadrature axis. The field established by the excitation of the stator poles is directed along the horizontal direct axis. This package presents computer models of electric machines based on the space vector formulation leading to the assessment of the dynamic performance of open- and closed-loopac and dc drive systems. The Simulink/Matlab implementation is adopted because of its inherent integration of vectorized system representations in block diagram form, of numerical analysis methods, of graphical portrayal of time evolutions of signals combined with the simple realization of the functionality of controllers and power electronic excitations. The development of Simulink models of drive assemblies is a relatively simple task consisting of combining input-output block representation of the various components making up the system; these blocks can readily be reused (utilizing standard copy-and-paste techniques) to modify the system components or the configuration of the system. This approach provides a powerful design tool because of the ease of observing the effects of parameters modifications and of differing system configurations and control strategies.

Riaz, Mahmoud

361

An electrochemical study of corrosion protection by primer-topcoat systems on 4130 steel with ac impedance and dc methods  

NASA Technical Reports Server (NTRS)

To investigate metal surface corrosion and the breakdown of metal protective coatings, the ac impedance method is applied to six systems of primer coated and primer topcoated 4130 steel. Two primers were used: a zinc-rich epoxy primer and a red lead oxide epoxy primer. The epoxy-polyamine topcoat was used in four of the systems. The EG and G-PARC Model 368 ac impedance measurement system, along with dc measurements with the same system using the polarization resistance method, were used to monitor changing properties of coated 4230 steel disks immersed in 3.5 percent NaCl solutions buffered at pH 5.4 over periods of 40 to 60 days. The corrosion system can be represented by an electronic analog called an equivalent circuit consisting of resistors and capacitors in specific arrangements. This equivalent circuit parallels the impedance behavior of the corrosion system during a frequency scan. Values for the resistors and capacitors, that can be assigned in the equivalent circuit following a least-squares analysis of the data, describe changes that occur on the corroding metal surface and in the protective coatings. Two equivalent circuits have been determined that predict the correct Bode phase and magnitude of the experimental sample at different immersion times. The dc corrosion current density data are related to equivalent circuit element parameters. Methods for determining corrosion rate with ac impedance parameters are verified by the dc method.

Mendrek, M. J.; Higgins, R. H.; Danford, M. D.

1988-01-01

362

The Geostationary Operational Satellite R Series SpaceWire Based Data System Architecture  

NASA Technical Reports Server (NTRS)

The GOES-R program selected SpaceWire as the best solution to satisfy the desire for simple and flexible instrument to spacecraft command and telemetry communications. Data generated by GOES-R instruments is critical for meteorological forecasting, public safety, space weather, and other key applications. In addition, GOES-R instrument data is provided to ground stations on a 24/7 basis. GOES-R requires data errors be detected and corrected from origin to final destination. This paper describes GOES-R developed strategy to satisfy this requirement

Krimchansky, Alexander; Anderson, William H.; Bearer, Craig

2010-01-01

363

Wires by Patchy Particles  

NSDL National Science Digital Library

Simulation Software: Glotzer Group Code Simulation Method: Brownian Dynamics A system of 80 spherical particles with two patches at a concentration of 0.20, was run starting at an effectively infinite temperature then instantaneously quenched to a temperature of 0.5. The final equillibrium structure is wires or chains. Simulation Model: United Atom Rigid Body with Lennard-Jones

Zhang, Zhenli

2005-01-31

364

Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System  

SciTech Connect

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower part of the UHV range. Measured NEG pump speed is high at pressures above 5×10^?11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.

M.L. Stutzman; P. Adderley; J. Brittian; J. Clark; J. Grames; J. Hansknecht; G.R. Myneni; M. Poelker

2007-05-01

365

Longitudinal inhomogeneity of DC current transport properties in Gd-system HTS tapes - Statistical approach for system design  

NASA Astrophysics Data System (ADS)

In this paper, we studied the DC current transport properties of GdBCO-coated conductors, including the longitudinal distribution of critical current. Inhomogeneity of the local critical current was firstly measured by means of TapeStar™ at 77 K, and then characterized based on a statistical method. Current transport properties were also measured for different positions and/or distances of potential taps using a four-probe method. It was shown that the longitudinal inhomogeneity of the conductor was described by use of a simplified percolation depinning model that takes account of Gaussian distribution. We further distinguished the above-mentioned inhomogeneity between statistical distribution and random failure. Influence of the aforementioned statistically distributed current transport properties on the magnet performance was also elucidated for simple pancake coils. This information is important as it provides guidance for practical system design.

Nakamura, T.; Takamura, Y.; Amemiya, N.; Nakao, K.; Izumi, T.

2014-09-01

366

NEMA wire and cable standards development programs  

NASA Technical Reports Server (NTRS)

The National Electrical Manufacturers Association (NEMA) is the nation's largest trade association for manufacturers of electrical equipment. Its member companies produce components, end-use equipment and systems for the generation, transmission, distribution, control and use of electricity. The wire and cable division is presented in 6 sections: building wire and cable, fabricated conductors, flexible cords, high performance wire and cable, magnet wire, and power and control cable. Participating companies are listed.

Baird, Robert W.

1994-01-01

367

Soft magnetic wires  

NASA Astrophysics Data System (ADS)

An overview of the present state of the art on the preparation techniques, outstanding magnetic properties and applications of soft magnetic micro and nanowires is presented. Rapid solidification techniques (in-rotating-water quenching and drawing methods) to fabricate amorphous microwires with diameter in the range from 100 down to 1 ?m are first described. Electrodeposition is also employed to prepare composite microtubes (magnetic coatings) and to fill porous membranes (diameter of the order of 0.1 ?m). Magnetic behaviours of interest are related to the different hysteresis loops of samples: square-shaped loops typical of bistable behaviour, and nearly non-hysteretic loop with well-defined transverse anisotropy field. The role played by magnetic dipolar interactions in the magnetic behaviour of arrays of micro and nanowires is described. A particular analysis is done on the giant magnetoimpedance (GMI) effect in the radio and microwave frequency ranges exhibited by ultrasoft microwires. Finally, a few examples of applications are introduced for magnetostrictive and non-magnetostrictive wires, they are: “magnetoelastic pens”, micromotors; DC current-sensors based on GMI, and sharpened amorphous wire tips in spin polarised scanning tunneling microscopy.

Vázquez, M.

2001-06-01

368

Beam profile wire-scanner/halo-scraper sensor analog interface electronics  

SciTech Connect

The halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory utilizes a generally traditional wire scanner for measurement of the beam core profile and a graphite scraper for measurement of the tails of the beam distribution. A lossy integrator is used to detect the replacement charge flowing to the wire and scraper. Independent programmable dc-bias voltages are applied to the wire and the scraper through the analog electronic interface to optimize charge capture from the two sensors. A programmable guard voltage is applied to isolate the scraper from the resistivity of the cooling system. Programmable gain provides a total dynamic range in the analog electronics of greater than about one part in 10{sup 6}. The analog signal is digitized to 14 bits plus sign, and the equivalent input noise is nominally 30fC.

Gruchalla, M. E.; O'Hara, J. F. (James F.); Barr, D. S. (Dean S.); Day, L. A. (Lisa A.); Gilpatrick, J. D. (John Douglas); Stettler, M. W. (Matthew W.); Martinez, D. G. (Derwin G.)

2001-04-01

369

In vitro system for studying interactions between Citrus exocortis viroid and Gynura aurantiaca (Blume) DC. metabolism and growing conditions  

Microsoft Academic Search

Citrus exocortis viroid (CEVd) is an economically important plant pathogen, which infects a broad range of hosts. In order to investigate complex interactions among viroid, host-growing conditions, and plant secondary metabolism, we setup an in vitro system for the cultivation of CEVd-infected and viroid-free Gynura aurantiaca (Blume) DC. shoots. Both basal Murashige and Skoog (MS) medium and MS medium supplemented

Silvija ?erni; Mirna ?urkovi?-Perica; Gordana Rusak; Dijana Škori?

2011-01-01

370

In vitro system for studying interactions between Citrus exocortis viroid and Gynura aurantiaca (Blume) DC. metabolism and growing conditions  

Microsoft Academic Search

Citrus exocortis viroid (CEVd) is an economically important plant pathogen, which infects a broad range of hosts. In order to investigate complex interactions among viroid, host-growing conditions, and plant secondary metabolism, we setup an in vitro system for the cultivation of CEVd-infected and viroid-free Gynura aurantiaca (Blume) DC. shoots. Both basal Murashige and Skoog (MS) medium and MS medium supplemented

Silvija ?erni; Mirna ?urkovi?-Perica; Gordana Rusak; Dijana Škori?

2012-01-01

371

Design and Implementation of a Fully Digital DC Servo System Based on a Single-Chip Microcomputer  

Microsoft Academic Search

A single-chip microcomputer is used to design a fully digital dc servo system to replace the conventional analog circuits. This microcomputer performs three main tasks: the firing control of a three-phase full-wave thyristor dual converter; the compensation for the nonlinear and loading effect in the converter; and compensations of position loop and rate loop. With no current feedback and minimum

Pei-Chong Tang; Shui-Shong Lu; Yung-Chun Wu

1982-01-01

372

Novel Radiopaque UHMWPE Sublaminar Wires in a Growth-Guidance System for the Treatment of Early Onset Scoliosis: Feasibility in a Large Animal Study.  

PubMed

Study Design. In vivo analysis in an ovine model.Objective. To evaluate the feasibility of radiopaque UHMWPE sublaminar wires in a growth-guidance spinal system by assessing stability, biocompatibility and growth potential.Summary of Background Data. Several growth-guidance systems have been developed for the treatment of early onset scoliosis (EOS). The use of gliding pedicle screws and metal sublaminar wires during these procedures can cause metal-on-metal debris formation and neurological deficits. Novel radiopaque UHMWPE wires are introduced to safely facilitate longitudinal growth and provide stability in a growth-guidance system for EOS.Methods. Twelve immature sheep received posterior segmental spinal instrumentation; pedicle screws were inserted at L5 and radiopaque UHWMPE (bismuth trioxide) wires were passed sublaminarly at each level between L3 and T11 and fixed to dual cobalt-chromiun rods. Four age-matched, unoperated animals were evaluated to serve as a control group. Radiographs were taken to measure growth of the instrumented segment. After 24 weeks, the animals were sacrificed and the spines were harvested for histological evaluation and high resolution peripheral quantitative computed tomography (HR-pQCT) analysis.Results. No neurological deficits occurred and all instrumentation remained stable. One animal died from an unknown cause. Substantial growth occurred in the instrumented segments (L5-T11) in the intervention group (27± 2 mm), which was not significantly different to the control group, (30 ± 4mm, p = 0.42). HR-pQCT analysis clearly showed safe routing and fixation of the UHMWPE wires and instrumentation. Despite the noted growth, ectopic bone formation with the formation of bony bridges was observed in all animals. Histology revealed no evidence of chronic inflammation or wear debris.Conclusions. This study shows the first results of radiopaque UHMWPE sublaminar wires as part of a growth guidance spinal system. UHMWPE sublaminar wires facilitated near-normal longitudinal spinal growth. All instrumentation remained stable throughout follow-up; no wire breakage or loosening occurred and no adverse local tissue response to these wires was observed. PMID:25271492

Bogie, R; Roth, Ak; Faber, S; de Jong, Jja; Welting, Tjm; Willems, Pc; Arts, Jj; van Rhijn, Lw

2014-09-29

373

Hierarchical assembly of a dual-responsive macroscopic insulated molecular wire bundle in a gradient system.  

PubMed

Here, we report the hierarchical self-assembly of a cationic gemini amphiphile, Azo 1, in a composition gradient solution generated using solvent evaporation. As the gradient solution is formed, Azo 1 forms nanorods in the lower region of the solution. Depending on solvent composition, these nanorods can further develop into nanofibres, which can then intertwine to form double helices and other types of nanohelices in the upper region of the solution. Finally, a macroscopic wire bundle is formed via the fusion of nanohelices; this ribbon-like bundle exhibits elasticity and linear ohmic resistance properties. More intriguingly, this bundle exhibits photoresponsive properties that affect its deformation and conductivity, as well as a rapid electroresponse that affects its conductivity, indicating that it is feasible to control the charge pathway. PMID:25588881

Sheng, Yujie; Chen, Qibin; Yao, Junyao; Wang, Ying; Liu, Honglai

2015-01-01

374

Hierarchical Assembly of a Dual-responsive Macroscopic Insulated Molecular Wire Bundle in a Gradient System  

NASA Astrophysics Data System (ADS)

Here, we report the hierarchical self-assembly of a cationic gemini amphiphile, Azo 1, in a composition gradient solution generated using solvent evaporation. As the gradient solution is formed, Azo 1 forms nanorods in the lower region of the solution. Depending on solvent composition, these nanorods can further develop into nanofibres, which can then intertwine to form double helices and other types of nanohelices in the upper region of the solution. Finally, a macroscopic wire bundle is formed via the fusion of nanohelices; this ribbon-like bundle exhibits elasticity and linear ohmic resistance properties. More intriguingly, this bundle exhibits photoresponsive properties that affect its deformation and conductivity, as well as a rapid electroresponse that affects its conductivity, indicating that it is feasible to control the charge pathway.

Sheng, Yujie; Chen, Qibin; Yao, Junyao; Wang, Ying; Liu, Honglai

2015-01-01

375

Superconducting wires  

SciTech Connect

The requirement of high critical current density has prompted extensive research on ceramic processing of high-T/sub c/ superconductors. An overview of wire fabrication techniques and the limitations they impose on component design will be presented. The effects of processing on microstructure and critical current density will also be discussed. Particle alignment has been observed in extruded samples which is attributed to high shear stresses during plastic forming. Composites of superconductor and silver in several configurations have been made with little deleterious effect on the superconducting properties. 35 refs., 2 figs., 1 tab.

Lanagan, M.T.; Poeppel, R.B.; Singh, J.P.; Dos Santos, D.I.; Lumpp, J.K.; Dusek, J.T.; Goretta, K.C.

1988-06-01

376

Chemical Evolution in Upper Tropospheric Convective Outflow: Case Study of a Mesoscale Convective System During DC3 (Invited)  

NASA Astrophysics Data System (ADS)

The jointly sponsored NSF/NASA/NOAA Deep Convective Clouds and Chemistry Project (DC3) took place during summer of 2012 to investigate the impact of deep convection over central North America on upper tropospheric composition and chemistry. On June 21, coordinated successive flights by the DC8 and GV aircraft successfully captured photochemical aging within and along the outflow of a decaying Mesoscale Convective System. Increases in ozone, HNO3, and PANs, accompanied by decreases in CH2O, NOx, VOCs and OVOCs are qualitatively consistent with persistent photochemistry for up to 12 daylight hours following the convective perturbations. The extended chemical processing is examined in detail using this rich data set and predictions of chemical evolution from the NASA LaRC Lagrangian photochemical box model, constrained with time varying observations of precursors along segments of the outflow.

Olson, J. R.; Crawford, J. H.; Diskin, G. S.; Sachse, G. W.; Blake, D. R.; Blake, N. J.; Brune, W. H.; Zhang, L.; Ren, X.; Mao, J.; Cohen, R. C.; Nault, B.; Dibb, J. E.; Cantrell, C. A.; Fried, A.; Richter, D.; Weibring, P.; Apel, E. C.; Flocke, F. M.; Hall, S. R.; Hornbrook, R. S.; Ullmann, K.; Weinheimer, A. J.; Hanisco, T. F.; Ryerson, T. B.; Crounse, J.; St Clair, J. M.; Wennberg, P. O.; Wisthaler, A.; Mikoviny, T.

2013-12-01

377

Composite ceramic superconducting wires for electric motor applications  

NASA Astrophysics Data System (ADS)

A scaled-up process for producing sintered, silver coated YBCO mono filament wire was developed and is currently able to produce 30 meters of wire/day. Efforts aimed at improving the electrical performance of this wire are well underway. Two approaches are being used: Continuously melt-texturing sintered YBCO wire/fiber to produce a macro-crystalline, strong-linked wire, and adaptation the TBCO process to the production of BiSCCO wire which can be subsequently mechanically textured by rolling the wire into ribbon. Work has also proceeded on the fabrication of a brushless DC trapped flux motor in which melt-textured YBCO rings are used as permanent magnet replicas. This motor design holds the potential for a high power HTSC motor which can be fabricated using current HTSC technology.

Hodge, James D.

1990-09-01

378

DC to DC power converters and methods of controlling the same  

DOEpatents

A power generation system configured to provide direct current (DC) power to a DC link is described. The system includes a first power generation unit configured to output DC power. The system also includes a first DC to DC converter comprising an input section and an output section. The output section of the first DC to DC converter is coupled in series with the first power generation unit. The first DC to DC converter is configured to process a first portion of the DC power output by the first power generation unit and to provide an unprocessed second portion of the DC power output of the first power generation unit to the output section.

Steigerwald, Robert Louis; Elasser, Ahmed; Sabate, Juan Antonio; Todorovic, Maja Harfman; Agamy, Mohammed

2012-12-11

379

Switching coordination of distributed dc-dc converters for highly efficient photovoltaic power plants  

DOEpatents

A distributed photovoltaic (PV) power plant includes a plurality of distributed dc-dc converters. The dc-dc converters are configured to switch in coordination with one another such that at least one dc-dc converter transfers power to a common dc-bus based upon the total system power available from one or more corresponding strings of PV modules. Due to the coordinated switching of the dc-dc converters, each dc-dc converter transferring power to the common dc-bus continues to operate within its optimal efficiency range as well as to optimize the maximum power point tracking in order to increase the energy yield of the PV power plant.

Agamy, Mohammed; Elasser, Ahmed; Sabate, Juan Antonio; Galbraith, Anthony William; Harfman Todorovic, Maja

2014-09-09

380

Design of DC\\/DC Boost converter with FNN solar cell Maximum Power Point Tracking controller  

Microsoft Academic Search

This paper demonstrates the Maximum Power Point Tracking (MPPT) controller that uses a DC\\/DC Boost converter with a Fuzzy Neural Network (FNN) system. It simplifies the topology of the DC\\/DC boost converter model to state equations, which is easy to simulate with Matlab. Additionally, the FNN system uses an integrated Fuzzy and Neural Network (NN), which advantages include uncertainty information

Hung-Ching Lu; Te-Lung Shih

2010-01-01

381

VOLTAGE COLLAPSE AND TRANSIENT ENERGY FUNCTION ANALYSES OF AC/DC SYSTEMS  

E-print Network

of up to 2158 buses, considering a variety of operational limits and controls, namely, ac/dc regulating transformer tap limits, voltage and reactive power limits, and area interchange control. AC generator reactive her I would have never realized my dreams. In closure, I hope that all what I have learned during

Cañizares, Claudio A.

382

DC Electronics  

NSDL National Science Digital Library

This is a website with many learning objects on DC Electronics with over 60 lessons in areas including: Basic Concepts, Electrical Circuits / Meters, Ohm's Law, Magnetism, Parallel Circuits, Series/Parallel Circuits, Series/Parallel Applications and Series Circuits.

383

Improved Method of Locating Defects in Wiring Insulation  

NASA Technical Reports Server (NTRS)

An improved method of locating small breaches in insulation on electrical wires combines aspects of the prior dielectric withstand voltage (DWV) and time-domain reflectometry (TDR) methods. The method was invented to satisfy a need for reliably and quickly locating insulation defects in spacecraft, aircraft, ships, and other complex systems that contain large amounts of wiring, much of it enclosed in structures that make it difficult to inspect. In the DWV method, one applies a predetermined potential (usually 1.5 kV DC) to the wiring and notes whether the voltage causes any arcing between the wiring and ground. The DWV method does not provide an indication of the location of the defect (unless, in an exceptional case, the arc happens to be visible). In addition, if there is no electrically conductive component at ground potential within about 0.010 in. (approximately equal to 0.254 mm) of the wire at the location of an insulation defect, then the DWV method does not provide an indication of the defect. Moreover, one does not have the option to raise the potential in an effort to increase the detectability of such a defect because doing so can harm previously undamaged insulation. In the TDR method as practiced heretofore, one applies a pulse of electricity having an amplitude of less than 25 V to a wire and measures the round-trip travel time for the reflection of the pulse from a defect. The distance along the wire from the point of application of the pulse to the defect is then calculated as the product of half the round-trip travel time and the characteristic speed of a propagation of an electromagnetic signal in the wire. While the TDR method as practiced heretofore can be used to locate a short or open circuit, it does not ordinarily enable one to locate a small breach in insulation because the pulse voltage is too low to cause arcing and thus too low to induce an impedance discontinuity large enough to generate a measurable reflection. The present improved method overcomes the weaknesses of both the prior DWV and the prior TDR method.

Greulich, Owen R.

2004-01-01

384

Fabrication of tungsten wire needles  

SciTech Connect

Fine point needles for field emissoin are conventionally produced by electrolytically or chemically etching tungsten wire. Points formed in this manner have a typical tip radius of about 0.5 microns and a cone angle of some 30 degrees. The construction of needle matrix detector chambers has created a need for tungsten needles whose specifications are: 20 mil tungsten wire, 1.5 inch total length, 3 mm-long taper (resulting in a cone angle of about 5 degrees), and 25 micron-radius point (similar to that found on sewing needles). In the process described here for producing such needles, tungsten wire, immersed in a NaOH solution and in the presence of an electrode, is connected first to an ac voltage and then to a dc supply, to form a taper and a point on the end of the wire immersed in the solution. The process parameters described here are for needles that will meet the above specifications. Possible variations will be discussed under each approprite heading.

Roder, A.

1983-02-01

385

Current dependence of heat leak on the terminals in the superconducting DC transmission and distribution system of CASER-2  

NASA Astrophysics Data System (ADS)

Superconductivity can solve the energy problems in the world as energy saving technologies. In particular, superconducting direct current (DC) transmission and distribution (T&D) systems is promising, as it can be easily extended to large scale energy transmission systems for energy sharing. We are developing criogenic systems for effective cooling of superconducting T&D systems. In the cooling experiments with the 200 m-class superconducting DC T&D system at Chubu University (CASER-2), we have estimated the performance of the system. For example, our superconducting cable is connected to the outside at the terminals using Peltier current leads (PCLs). The PCL is composed of a thermoelectric material and a copper lead. Small thermal conductivity and large thermopower of the thermoelectric modules can effectively insulate the heat leak to the low temperature end. We measured the temperature along the current leads and the heat leak at the terminals. As current leads have an optimal shape factor, the optimum operation current exists. The current dependence of the system performance is discussed.

Kawahara, Toshio; Watanabe, Hirofumi; Emoto, Masahiko; Hamabe, Makoto; Yamaguchi, Sataro; Hikichi, Yasuo; Minowa, Masahiro

2012-12-01

386

RcsCDB His-Asp phosphorelay system negatively regulates the flhDC operon in Escherichia coli.  

PubMed

The genes involved in flagellum synthesis, motility and chemotaxis in Escherichia coli are expressed in a hierarchical fashion. At the top of the hierarchy lies the master regulator FlhDC, required for the expression of the whole set of genes. The operon flhDC is controlled by numerous regulators including H-NS, CRP, EnvZ/OmpR, QseBC and LrhA. In the present work, we report that the flhDC operon is also negatively regulated by the His-Asp phosphorelay system RcsCDB. The regulation is potentiated by the RcsB cofactor RcsA. Genetic analysis indicates that an RcsAB box, located downstream of the promoter, is required for the regulation. The binding of RcsB and RcsA to this site was demonstrated by gel retardation and DNase I protection assays. In addition, mutation analysis suggests that RcsA-specific determinants lie in the right part of the 'RcsAB box'. PMID:12864862

Francez-Charlot, Anne; Laugel, Bruno; Van Gemert, Alice; Dubarry, Nelly; Wiorowski, Florent; Castanié-Cornet, Marie-Pierre; Gutierrez, Claude; Cam, Kaymeuang

2003-08-01

387

A simplified post process for wire cut EDM  

Microsoft Academic Search

The paper deals with a technical realization to improve the Wire EDM accuracy while cutting at full speed on virtually any contour. The system which is readily available on commercial wire EDM machines is based on the on-line monitoring and control of the wire position by means of an optical sensor. The deviation of the wire position relative to the

Ivano Beltrami; Axel Bertholds; Dirk Dauw

1996-01-01

388

Preparation of hydrogenated microcrystalline silicon films with hot-wire-assisted MWECR-CVD system  

NASA Astrophysics Data System (ADS)

Intrinsic hydrogenated microcrystalline silicon (?c-Si:H) films have been prepared by hot-wire-assisted microwave electron-cyclotron-resonance chemical vapour deposition (HW-MWECR-CVD) under different deposition conditions. Fourier-transform infrared spectra and Raman spectra were measured. Optical band gap was determined by Tauc plots and experiments of photo-induced degradation were performed. It was observed that hydrogen dilution plays a more essential role than substrate temperature in microcrystalline transformation at low temperatures. Crystalline volume fraction and mean grain size in the films increase with the dilution ratio (R=H2/(H2+SiH4)). With the rise of crystallinity in the films, the optical band gap tends to become narrower while the hydrogen content and photo-induced degradation decrease dramatically. The samples, were identified as ?c-Si:H films, by calculating the optical band gap. It is considered that hydrogen dilution has an effect on reducing the crystallization activation energy of the material, which promotes the heterogeneous solid-state phase transition characterized by the Johnson-Mehl-Avrami (JMA) equation. The films with the needed structure can be prepared by balancing deposition and crystallization through controlling process parameters.

He, Bin; Chen, Guang-Hua; Zhu, Xiu-Hong; Zhang, Wen-Li; Ding, Yi; Ma, Zhan-Jie; Gao, Zhi-Hua; Song, Xue-Mei; Deng, Jin-Xiang

2006-04-01

389

Composite superconducting wires obtained by high-rate tinning in molten Bi-Pb-Sr-Ca-Cu-O system  

NASA Technical Reports Server (NTRS)

The preparation of high-T(sub c) superconducting long composite wires by short-time tinning of the metal wires in a molten Bi-Pb-Sr-Ca-Cu-O compound is discussed. The application of this method to the high-T(sub c) materials is tested, possibly for the first time. The initial materials used for this experiment were ceramic samples with nominal composition Bi(1.5)Pb(0.5)Sr2Ca2Cu3O(x) and T(sub c) = 80 K prepared by the ordinary solid-state reaction, and industrial copper wires from 100 to 400 microns in diameter and from 0.5 to 1 m long. The continuously moving wires were let through a small molten zone (approximately 100 cubic mm). The Bi-based high-T(sub c) ceramics in a molten state is a viscous liquid and it has a strongly pronounced ability to spread on metal wire surfaces. The maximum draw rate of the Cu-wire, at which a dense covering is still possible, corresponds to the time of direct contact of wire surfaces and liquid ceramics for less than 0.1 s. A high-rate draw of the wire permits a decrease in the reaction of the oxide melt and Cu-wire. This method of manufacture led to the fabrication of wire with a copper core in a dense covering with uniform thickness of about h approximately equal to 5 to 50 microns. Composite wires with h approximately equal to 10 microns (h/d approximately equal to 0.1) sustained bending on a 15 mm radius frame without cracking during flexing.

Grozav, A. D.; Konopko, L. A.; Leporda, N. I.

1990-01-01

390

COBRA-STAR, a five frame point-projection x-ray imaging system for 1 MA scale wire-array Z pinches.  

PubMed

A new imaging system for 1 MA scale wire-array Z-pinch experiments that produces up to five high-resolution x-ray images per experimental pulse has been developed. Calibrated areal density measurements of the Z-pinch plasma can be obtained from each pulse. The system substitutes five molybdenum (Mo) X pinches for the normal copper return-current conductors to provide point sources of x-rays for point-projection radiography. Each backlighting X pinch consists of four Mo wires, the x-ray burst timing of which was controlled by varying the wire diameter (mass) from 10.2 to 30 microm in the five X pinches. Typical images have a 16x8 mm2 field of view at the wire array and a magnification of about 6.5:1 on the x-ray-sensitive film. Titanium (Ti) filters in front of the films transmit continuum radiation in the spectral range of 3-5 keV. Inclusion on the Ti of a step wedge having known thickness increments of the same material as the wires enables the calibrated areal density measurements to be made of the exploding wire plasmas. Here, we used tungsten (W) step wedges with step thicknesses ranging from 0.015 to 1.1 microm to obtain accurate (+/-10%) areal density measurements of W plasmas from the spatial profile of film exposure. When imaging arrays that produce intense radiation pulses, a plastic monofilament "quencher" is placed on axis to avoid film saturation. Images have subnanosecond temporal resolution and about 7 microm spatial resolution. PMID:18377006

Douglass, J D; Hammer, D A

2008-03-01

391

4He sample probe for combined microwave and dc transport measurements  

NASA Astrophysics Data System (ADS)

Combined microwave and dc electrical transport measurements at low temperatures represent a valuable experimental method in many research areas. In particular, when samples are conventional superconductors, a typical experiment requires a combination of helium temperatures, a wide range of magnetic fields, and the utilization of coaxial lines along with the usual dc wiring. We report on the general design features and the microwave performance of a custom-made low-temperature sample probe, with a measurement bandwidth tested from dc to 20 GHz. Equipped with six coaxial cables, a heater, Hall and temperature sensors, the probe fits into a ?32 mm shaft. We present our setup, analyze its microwave performance, and describe two representative experiments enabled by this system. The proposed setup will be essential for a systematic study of the dc and ac response of the vortex dynamics in nanopatterned superconductors subject to combined dc and microwave stimuli. Besides, it will be valuable for the investigation of a broad class of nonlinear stochastic systems where a combination of dc and high-frequency ac driving in a wide temperature range is necessary.

Dobrovolskiy, Oleksandr V.; Franke, Jörg; Huth, Michael

2015-03-01

392

ac characteristics in ac\\/dc\\/dc conversion  

Microsoft Academic Search

The ac characteristics of a double-conversion system are investigated. Using a simple method, the harmonic composition of the alternating currents are determined as a function of the connection type of the ac\\/dc rectifier and of the parameters characterizing the dc\\/dc chopper operations. It is shown that the best ac characteristics are only achieved when the chopper modulation frequency is a

P. Marino; C. Picardi; A. Russo

1983-01-01

393

Application of medium frequency atmospheric plasma on continuous aluminum wire cleaning for magnet wire manufacturing  

Microsoft Academic Search

Recently, the study on the application of atmospheric plasma treatment has gradually increased because it requires high cost vacuum systems, and the flexibility of application to a continuous process. This paper reports on the new application of medium frequency atmospheric plasma to the continuous surface cleaning of aluminum wire for magnet wire manufacturing. Magnet wire is widely used for transformers

In S Choi; Seok W Hwang; Jong C Park

2001-01-01

394

Experimental investigations on a permanent magnet brushless DC motor fed by PV array for water pumping system  

SciTech Connect

This paper describes the experimental study carried out on a Permanent Magnet Brushless DC (PMBLDC) Motor drive coupled to a pump load powered by photovoltaic (PV) array for water pumping system. A simple low cost prototype controller has been designed and developed without current and position sensors which reduces drastically the overall cost of the drive system. This controller is used to test the dynamic behavior of the PMBLDC motor drive system. The mathematical model of the system is developed with a view to carrying out a comparison between experimental and simulated response of the drive system. The necessary computer algorithm is developed to analyze the performance under different conditions of varying solar insolation for a pump load. The developed state space equations are simulated to obtain the performance characteristics which are also verified by conducting suitable experiments on the development system.

Putta Swamy, C.L.; Singh, B.; Singh, B.P.; Murthy, S.S. [IIT Delhi, New Delhi (India). Dept. of Electrical Engineering

1996-12-31

395

Control of AC\\/DC\\/AC Converter for Multi MW Wave Dragon Offshore Energy Conversion System  

Microsoft Academic Search

In the paper a direct power and torque control-space vector modulated (DPTC-SVM) algorithm for AC\\/DC\\/AC converter is presented. This strategy leads to good dynamic and static behaviors. Additional power feedforward (PF) loop from a generator side converter (GSC) to line side converter (LSC) control improves dynamic of the power flow. As a result, more accurate input-output energy matching allows better

M. Jasinski; M. Malinowski; M. P. Kazmierkowski; H. C. Sorensen; E. Friis-Madsen; D. Swierczynski

2007-01-01

396

Superconducting film on metallic wire  

NASA Technical Reports Server (NTRS)

For technological applications of high T(sub c) superconductors, it will be necessary to overcome the inherent problem of brittleness, to develop materials with high current carrying capacity, and to devise ways of joining superconductors with other materials. These issues will be addressed in the context of superconducting films on metallic wires. These composite systems are expected to produce flexible wires with desirable properties.

Akbar, Sheikh A.

1990-01-01

397

A comparison of soft-switched DC-to-DC converters for electrolyser application  

Microsoft Academic Search

An Electrolyser is part of a renewable energy system (RES) and generates hydrogen from water electrolysis that is used in fuel cells. A dc-to-dc converter is required to couple the Electrolyser to the system DC bus. This paper presents the design of three soft-switched high-frequency transformer isolated dc-to-dc converters for this application based on the given specifications. It is shown

Deepak S. Gautam; A. K. S. Bhat

2006-01-01

398

High performance dc-dc conversion with voltage multipliers  

NASA Technical Reports Server (NTRS)

The voltage multipliers using capacitors and diodes first developed by Cockcroft and Walton in 1932 were reexamined in terms of state of the art fast switching transistors and diodes, and high energy density capacitors. Because of component improvements, the voltage multiplier, used without a transformer, now appears superior in weight to systems now in use for dc-dc conversion. An experimental 100-watt 1000-volt dc-dc converter operating at 100 kHz was built, with a component weight of about 1 kg/kW. Calculated and measured values of output voltage and efficiency agreed within experimental error.

Harrigill, W. T.; Myers, I. T.

1974-01-01

399

Windows: Life after Wire.  

ERIC Educational Resources Information Center

Although wired glass is extremely common in school buildings, the International Building Code adopted new standards that eliminate the use of traditional wired glass in K-12 schools, daycare centers, and athletic facilities. Wired glass breaks easily, and the wires can cause significant injuries by forming dangerous snags when the glass breaks.…

Razwick, Jerry

2003-01-01

400

The Future of Wires  

Microsoft Academic Search

Concern about the performance of wires in scaled technologies has led to research exploring other communication methods. This paper examines wire and gate delays as technologies migrate from 0.18- m to 0.035- m feature sizes to better understand the magni- tude of the wiring problem. Wires that shorten in length as technolo- gies scale have delays that either track gate

RON HO; KENNETH W. MAI; MARK A. HOROWITZ

1999-01-01

401

The UT 19-channel DC SQUID based neuromagnetometer.  

PubMed

A 19-channel DC SQUID based neuromagnetometer is under construction at the University of Twente (UT). Except for the cryostat all elements of the system are developed at the UT. It comprises 19 wire-wound first-order gradiometers in a hexagonal configuration. The gradiometers are connected to planar DC SQUIDs fabricated with a Nb/Al, AlO kappa/Nb technology. For this connection we developed a method to bond a Nb wire to a Nb thin-film. The SQUIDs are placed in compartmentalised Nb modules. Further, external feedback is incorporated in order to eliminate cross talk between the gradiometers. The electronics basically consist of a phase-locked loop operating with a modulation frequency of 100 kHz. Between SQUID and preamplifier a small transformer is used to limit the noise contribution of the preamplifier. In the paper the overall system is described, and special attention is paid to the SQUID module (bonding, compartments, external-feedback setup, output transformer). PMID:1807878

ter Brake, H J; Flokstra, J; Jaszczuk, W; Stammis, R; van Ancum, G K; Martinez, A; Rogalla, H

1991-01-01

402

Auxiliary resonant DC tank converter  

DOEpatents

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

Peng, Fang Z. (Knoxville, TN)

2000-01-01

403

HTS Wire Development Workshop: Proceedings  

SciTech Connect

The 1994 High-Temperature Superconducting Wire Development Workshop was held on February 16--17 at the St. Petersburg Hilton and Towers in St. Petersburg, Florida. The meeting was hosted by Florida Power Corporation and sponsored by the US Department of Energy`s Superconductivity Program for Electric Power Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. The meeting opened with a general discussion on the needs and benefits of superconductivity from a utility perspective, the US global competitiveness position, and an outlook on the overall prospects of wire development. The meeting then focused on four important technology areas: Wire characterization: issues and needs; technology for overcoming barriers: weak links and flux pinning; manufacturing issues for long wire lengths; and physical properties of HTS coils. Following in-depth presentations, working groups were formed in each technology area to discuss the most important current research and development issues. The working groups identified research areas that have the potential for greatly enhancing the wire development effort. These areas are discussed in the summary reports from each of the working groups. This document is a compilation of the workshop proceedings including all general session presentations and summary reports from the working groups.

Not Available

1994-07-01

404

Direct Current Measurement Based Steer-By-Wire Systems for Realistic Driving Feeling  

E-print Network

sensor is used to fully measure the steering torque on the rack of steering mechanism. This measured is transmitted through mechanical and, or hydraulic linkages in conventional steering systems. Thanks as conventional hydraulic steering systems. The force feedback for SBW systems has been studied by many

Ryu, Jee-Hwan

405

DC Biotech  

NSDL National Science Digital Library

DC Biotech is a student-centered project dedicated to encourage and assist Washington DC public school students to pursue careers in the rapidly growing, multi-billion dollar Biotechnology industry. DCBiotech's NSF award states: "The DC Biotech project is creating a Washington, DC area consortium to improve student competencies in science, broaden students' career opportunities, and improve biotechnology workforce diversity. Project Objectives include providing professional development for teachers including research opportunities, summer training, online coursework, and in-school/class mentoring so they can prepare their students for the biotech workplace; providing support for students to intern to gain experience in a professional workplace; establishing, with the DCPS Office of Career and Technical Education (OCTE) and our workplace partners, a certificate of employability in biotechnology; establishing, with OCTE and Montgomery College, coursework articulation that will prepare graduates of the high school biotech program for further study. The site currently only provides information on the project but looks to add resources for both students and teachers in the future.

406

The future of wires  

Microsoft Academic Search

Concern about the performance of wires wires in scaled technologies has led to research exploring other communication methods. This paper examines wire and gate delays as technologies migrate from 0.18-?m to 0.035-?m feature sizes to better understand the magnitude of the the wiring problem. Wires that shorten in length as technologies scale have delays that either track gate delays or

RON HO; KENNETH W. MAI; MARK A. HOROWITZ

2001-01-01

407

Stretched Wire Mechanics  

SciTech Connect

Stretched wires are beginning to play an important role in the alignment of accelerators and synchrotron light sources. Stretched wires are proposed for the alignment of the 130 meter long LCLS undulator. Wire position technology has reached sub-micron resolution yet analyses of perturbations to wire straightness are hard to find. This paper considers possible deviations of stretched wire from the simple 2-dimensional catenary form.

Bowden, Gordon; /SLAC

2005-09-06

408

Characteristics of the multiple-input DC-DC converter  

Microsoft Academic Search

A multiple-input DC-DC converter is proposed for realizing a clean electric power generation system. The two-input buck-boost type converter is analyzed, and the static and dynamic characteristics are clarified theoretically and are confirmed by experiment

H. Matsuo; T. Shigemizu; F. Kurokawa; N. Watanabe

1993-01-01

409

New classification of directly compressible (DC) excipients in function of the SeDeM Diagarm Expert System.  

PubMed

As a methodology for characterizing substances with regard to its viability in direct compression, the SeDeM Diagram Expert System may be considered a new tool in terms of the number of parameters applied and its optimization. The paper is based on the experimental SeDeM characterization study of 51 directly compressible (DC) excipients. After selecting the parameters, and comparing the corresponding results, the choices available within the SeDeM Expert System could be expanded. Through applied variants, the maximum and optimal values of the DC diluent excipient were precisely defined and the mathematical limits of the parameters, functions and parametric indices that define the level of direct compressibility were established. These studies have allowed us to propose a new classification of excipients CD based on its rheological and compressibility capability, resulting in a periodic table of CD excipients. It has been determined that the best excipient for direct compression should have an index of good compression (IGC) of 8.832. PMID:24792976

Suñé-Negre, Josep M; Roig, Manel; Fuster, Roser; Hernández, Carmen; Ruhí, Ramon; García-Montoya, Encarna; Pérez-Lozano, Pilar; Miñarro, Montserrat; Ticó, Josep R

2014-08-15

410

STAR-DUNDEE VIRTUAL DEVICES AND SYSTEM SIMULATION Session: SpaceWire Test and Verification Short Paper  

Microsoft Academic Search

STAR-Dundee's latest software API and applications allow users to build virtual SpaceWire networks on their PCs. Users can create their own virtual devices to represent hardware that may not yet be available, or to prototype features that aren't implemented in existing hardware. Virtual SpaceWire networks can then be constructed using these virtual devices. The virtual networks can also be integrated

Stuart Mills; Alex Mason; Steve Parkes

411

First-principles calculations of structural and electronic properties of Ta-doped Si clusters, wires, and bulk systems  

NASA Astrophysics Data System (ADS)

Recent experiments have shown that Ta@Si16+ is a very stable cation from which it should be possible to create Si-based cluster assembled materials. In this paper we have studied, by means of first-principles spin-dependent generalized gradient approximation calculations, the structural and electronic properties of the following systems: (i) Ta@Sin+ clusters in the range n=14-18; (ii) (Ta@Si16F)m aggregates with sizes m=1-8 formed by Ta@Si16F molecules; (iii) infinite wires formed by stacking triangular (Ta@Si16F)3 aggregates twisted 60° to each other along the vertical axis; and (iv) the fcc phase of bulk Ta@Si16F. The minimum-energy Ta@Si16+ cluster shows C3v symmetry, having 40 meV smaller total energy than a fullerenelike D4d isomer. However, the molecule Ta@Si16F formed with that D4d isomer is 40 meV more stable than that formed with the C3v one. We have optimized several [Ta@Si16F]n aggregates (n=1-8) which contain the Ta@Si16 unit with D4d symmetry. The more bound (Ta@Si16F)6 aggregate is formed by stacking vertically two triangular (Ta@Si16F)3 aggregates which are twisted 60° to each other. The infinite wire formed with that (Ta@Si16F)6 aggregate as the unit cell has a cohesive energy 1.88 eV and a small highest occupied molecular orbital-lowest occupied molecular orbital gap. We have optimized also a metastable fcc bulk phase having the Ta@Si16F supermolecule as the unit cell. A Birch-Murnaghan fit to that phase produces a cohesive energy 0.84 eV at lattice constant 12.27 Å, with bulk modulus 7.55 GPa and a phase stability to isotropic compression smaller than 0.75 GPa. That phase is nonmagnetic and shows a band gap of 0.20 eV. Using the values of hardness of Ta@Si16F molecules, we estimated a correction enhancement factor ~3 to that small band gap. For that metastable solid we performed a 13.5-ps run of first-principles molecular dynamics annealing at 300 K and constant volume, and we found that the Ta@Si16F supermolecule in the fcc cell becomes severely distorted after the first 5 ps.

Cantera-López, H.; Balbás, L. C.; Borstel, G.

2011-02-01

412

Chemistry of radiation damage to wire chambers  

SciTech Connect

Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

Wise, J.

1992-08-01

413

A compact algorithm for three-phase three-wire system reactive power compensation and load balancing  

SciTech Connect

A compact control algorithm for reactive power compensation and load balancing with the static var compensator (SVC) in three-phase three-wire systems is developed in this paper. Each phase susceptance of the SVC can be obtained from a very simple function of voltage and power signals which are measured by a three-phase voltage transducer and two single-phase active and reactive power (P-Q) transducers at the load bus. The calculation of compensation susceptances is based on the criterion of a unity power factor and zero sequence currents after compensation. A simulation is made, as the first stage, to show the validity of the proposed compensation algorithm. Then, a laboratory size microcomputer-based SVC, which consists of thyristor-controlled reactors (TCRs) and fixed capacitors (FCs), is designed and implemented. Simulation and experiment results show that the algorithm is very suitable for on-line control of the SVC which is designed for phase balancing and power factor correction.

Lee, S.Y. [Kao Yuan Junior Coll. of Technology and Commerce, Kaohsiung (Taiwan, Province of China). Dept. of Electrical Engineering; Chang, W.N.; Wu, C.J. [National Taiwan Inst. of Tech., Peitow-Taipei (Taiwan, Province of China). Dept. of Electrical Engineering

1995-12-31

414

Wire frame to MOVIE. BYU transfer program  

SciTech Connect

At SNLA, the primary computer-aided drafting tool is the Applicon Graphics System (AGS). The data base for mechanical parts on the AGS is a wire frame model. This report summarizes a method of adding surface information to the wire frame and passing this information up stream to MOVIE.BYU which is on a VAX computer and is used to produce shaded graphics pictures of the AGS wire frame model on a RAMTEK 9400 display terminal.

Robbins, D.; Byers, L.D.; Benner, M.S.

1982-12-01

415

DC attenuation meter  

DOEpatents

A portable, hand-held meter used to measure direct current (DC) attenuation in low impedance electrical signal cables and signal attenuators. A DC voltage is applied to the signal input of the cable and feedback to the control circuit through the signal cable and attenuators. The control circuit adjusts the applied voltage to the cable until the feedback voltage equals the reference voltage. The "units" of applied voltage required at the cable input is the system attenuation value of the cable and attenuators, which makes this meter unique. The meter may be used to calibrate data signal cables, attenuators, and cable-attenuator assemblies.

Hargrove, Douglas L.

2004-09-14

416

Bi-Directional DC-DC Converter for PHEV Applications  

SciTech Connect

Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DC converter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.

Abas Goodarzi

2011-01-31

417

DC arc weld starter  

DOEpatents

A system for starting an arc for welding uses three DC power supplies, a high voltage supply for initiating the arc, an intermediate voltage supply for sustaining the arc, and a low voltage welding supply directly connected across the gap after the high voltage supply is disconnected.

Campiotti, Richard H. (Tracy, CA); Hopwood, James E. (Oakley, CA)

1990-01-01

418

Flyback-Type Single-Phase Utility Interactive Inverter With Power Pulsation Decoupling on the DC Input for an AC Photovoltaic Module System  

Microsoft Academic Search

In recent years, interest in natural energy has grown in response to increased concern for the environment. Many kinds of inverter circuits and their control schemes for photovoltaic (PV) power generation systems have been studied. A conventional system employs a PV array in which many PV modules are connected in series to obtain sufficient dc input voltage for generating ac

Toshihisa Shimizu; Keiji Wada; Naoki Nakamura

2006-01-01

419

Structural homeostasis in the nervous system: a balancing act for wiring plasticity and stability  

PubMed Central

Experience-dependent modifications of neural circuits provide the cellular basis for functional adaptation and learning, while presenting significant challenges to the stability of neural networks. The nervous system copes with these perturbations through a variety of compensatory mechanisms with distinct spatial and temporal profiles. Mounting evidence suggests that structural plasticity, through modifications of the number and structure of synapses, or changes in local and long-range connectivity, might contribute to the stabilization of network activity and serve as an important component of the homeostatic regulation of the nervous system. Conceptually similar to the homeostatic regulation of synaptic strength and efficacy, homeostatic structural plasticity has a profound and lasting impact on the intrinsic excitability of the neuron and circuit properties, yet remains largely unexplored. In this review, we examine recent reports describing structural modifications associated with functional compensation in both developing and adult nervous systems, and discuss the potential role for structural homeostasis in maintaining network stability and its implications in physiological and pathological conditions of the nervous systems. PMID:25653587

Yin, Jun; Yuan, Quan

2015-01-01

420

Wired for behaviors: from development to function of innate limbic system circuitry  

PubMed Central

The limbic system of the brain regulates a number of behaviors that are essential for the survival of all vertebrate species including humans. The limbic system predominantly controls appropriate responses to stimuli with social, emotional, or motivational salience, which includes innate behaviors such as mating, aggression, and defense. Activation of circuits regulating these innate behaviors begins in the periphery with sensory stimulation (primarily via the olfactory system in rodents), and is then processed in the brain by a set of delineated structures that primarily includes the amygdala and hypothalamus. While the basic neuroanatomy of these connections is well-established, much remains unknown about how information is processed within innate circuits and how genetic hierarchies regulate development and function of these circuits. Utilizing innovative technologies including channel rhodopsin-based circuit manipulation and genetic manipulation in rodents, recent studies have begun to answer these central questions. In this article we review the current understanding of how limbic circuits regulate sexually dimorphic behaviors and how these circuits are established and shaped during pre- and post-natal development. We also discuss how understanding developmental processes of innate circuit formation may inform behavioral alterations observed in neurodevelopmental disorders, such as autism spectrum disorders, which are characterized by limbic system dysfunction. PMID:22557946

Sokolowski, Katie; Corbin, Joshua G.

2012-01-01

421

49 CFR 236.108 - Insulation resistance tests, wires in trunking and cables.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Insulation resistance tests, wires in trunking...Tests; All Systems § 236.108 Insulation resistance tests, wires in trunking and cables. (a) Insulation resistance of wires and...

2011-10-01

422

49 CFR 236.108 - Insulation resistance tests, wires in trunking and cables.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Insulation resistance tests, wires in trunking...Tests; All Systems § 236.108 Insulation resistance tests, wires in trunking and cables. (a) Insulation resistance of wires and...

2013-10-01

423

49 CFR 236.108 - Insulation resistance tests, wires in trunking and cables.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 2014-10-01 false Insulation resistance tests, wires in trunking...Tests; All Systems § 236.108 Insulation resistance tests, wires in trunking and cables. (a) Insulation resistance of wires and...

2014-10-01

424

49 CFR 236.108 - Insulation resistance tests, wires in trunking and cables.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Insulation resistance tests, wires in trunking...Tests; All Systems § 236.108 Insulation resistance tests, wires in trunking and cables. (a) Insulation resistance of wires and...

2012-10-01

425

49 CFR 236.108 - Insulation resistance tests, wires in trunking and cables.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Insulation resistance tests, wires in trunking...Tests; All Systems § 236.108 Insulation resistance tests, wires in trunking and cables. (a) Insulation resistance of wires and...

2010-10-01

426

Adsorption of selenium wires in silicalite-1 zeolite: a first order transition in a microporous system.  

PubMed

A tight binding grand canonical Monte Carlo simulation of the adsorption of selenium in silicalite-1 zeolite is presented. The calculated adsorption-desorption isotherms exhibit characteristic features of a first order transition, unexpected for adsorption in a microporous system with pore size of the order of 0.5 to 0.6 nm. We analyze this behavior as a result of the favored twofold coordinated chain structure of selenium that grows inside the complex three-dimensional microchannel network of silicalite. This analysis is confirmed by simpler calculations of a lattice gas-type model. PMID:12097054

Bichara, Christophe; Raty, Jean Yves; Pellenq, Roland J-M

2002-07-01

427

30 CFR 77.705 - Guy wires; grounding.  

Code of Federal Regulations, 2014 CFR

...Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be securely connected to the system ground or be provided with insulators installed near the pole...

2014-07-01

428

30 CFR 77.705 - Guy wires; grounding.  

Code of Federal Regulations, 2012 CFR

...Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be securely connected to the system ground or be provided with insulators installed near the pole...

2012-07-01

429

30 CFR 77.705 - Guy wires; grounding.  

Code of Federal Regulations, 2013 CFR

...Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be securely connected to the system ground or be provided with insulators installed near the pole...

2013-07-01

430

30 CFR 77.705 - Guy wires; grounding.  

Code of Federal Regulations, 2010 CFR

...Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be securely connected to the system ground or be provided with insulators installed near the pole...

2010-07-01

431

47 CFR 32.2321 - Customer premises wiring.  

Code of Federal Regulations, 2012 CFR

...COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions...232, Station Connections, inside wiring subclass. (b) Embedded Customer Premises Wiring is that investment in customer...

2012-10-01

432

47 CFR 32.2321 - Customer premises wiring.  

Code of Federal Regulations, 2011 CFR

...COMMISSION (CONTINUED) COMMON CARRIER SERVICES UNIFORM SYSTEM OF ACCOUNTS FOR TELECOMMUNICATIONS COMPANIES Instructions...232, Station Connections, inside wiring subclass. (b) Embedded Customer Premises Wiring is that investment in customer...

2011-10-01

433

30 CFR 77.705 - Guy wires; grounding.  

Code of Federal Regulations, 2011 CFR

...Grounding § 77.705 Guy wires; grounding. Guy wires from poles supporting high-voltage transmission lines shall be securely connected to the system ground or be provided with insulators installed near the pole...

2011-07-01

434

RISK D/C  

NASA Technical Reports Server (NTRS)

RISK D/C is a prototype program which attempts to do program risk modeling for the Space Exploration Initiative (SEI) architectures proposed in the Synthesis Group Report. Risk assessment is made with respect to risk events, their probabilities, and the severities of potential results. The program allows risk mitigation strategies to be proposed for an exploration program architecture and to be ranked with respect to their effectiveness. RISK D/C allows for the fact that risk assessment in early planning phases is subjective. Although specific to the SEI in its present form, RISK D/C can be used as a framework for developing a risk assessment program for other specific uses. RISK D/C is organized into files, or stacks, of information, including the architecture, the hazard, and the risk event stacks. Although predefined, all stacks can be upgraded by a user. The architecture stack contains information concerning the general program alternatives, which are subsequently broken down into waypoints, missions, and mission phases. The hazard stack includes any background condition which could result in a risk event. A risk event is anything unfavorable that could happen during the course of a specific point within an architecture, and the risk event stack provides the probabilities, consequences, severities, and any mitigation strategies which could be used to reduce the risk of the event, and how much the risk is reduced. RISK D/C was developed for Macintosh series computers. It requires HyperCard 2.0 or later, as well as 2Mb of RAM and System 6.0.8 or later. A Macintosh II series computer is recommended due to speed concerns. The standard distribution medium for this package is one 3.5 inch 800K Macintosh format diskette. RISK D/C was developed in 1991 and is a copyrighted work with all copyright vested in NASA. Macintosh and HyperCard are trademarks of Apple Computer, Inc.

Dias, W. C.

1994-01-01

435

Large Wire Strain Gauges  

NASA Technical Reports Server (NTRS)

Wires yield data on average strains over distances ranging from inches to many feet. Long constantan wires used to measure average strains over distances characteristic of vehicles or buildings. Connected in bridge circuit, wires measure strain accurately within 1 percent, and linearly, within 0.1 percent. Wires stretch as much as 0.15 percent and still return to zero residual strain after release.

Bryner, B. D.

1987-01-01

436

Design and characterization of the DC acceleration and transport system required for the IMW Free Electron Master experiment  

SciTech Connect

A Free Electron Maser (FEM) has been constructed and is soon to be tested at the FOM Institute (Rijnhuizen) Netherlands with the ultimate goal of producing 1 MW long pulse to CW microwave output in the range 130 GHz to 250 GHz. The DC acceleration and beam transport systems is eventually to be used in a depressed collector configuration requiring 99.8% beam transmission in order that the High Voltage 2MV supply be required only to supply 20 milliamps of body current. A relativistic version of the Herrmann optical theory originally developed for microwave tube beams is used to take in account thermal electrons far out on the gaussian distribution tail which can translate into beam current well outside the ideal beam edge. This theory is applied to the FOM beamline design and predicts that the beam envelope containing 99.8% of the current can be successfully transported to the undulator for a wide range of assume d emittance values.

Caplan, M. [Lawrence Livermore National Lab., CA (United States); Van Der Geer, C.; Valentini, M.; Urbanus, W. [FOM-Instituut voor Plasmafysica, Rijnhuizen (Netherlands)

1995-08-01

437

Dc and AC Conductivity Studies on Ag2O-P2O5-V2O5 Glass System  

NASA Astrophysics Data System (ADS)

Composition, temperature and frequency dependence conductivity studies have been carried out on xAg2O-(50-x)P2O5-50V2O5 (x = 5 to 40 mol%) glass system. The dc conductivity is found to increase with increase of Ag2O concentration up to 30 mol% and further increase of Ag2O concentration the conductivity decreases sharply. The activation energy also shows compositional dependence. The ac conductivity data has been analyzed by fitting the data in to Almond-West type power law behaviour ? (?) = ? (0) + A ?s. The values of s were found to decrease with the increase of temperature and show a weak minimum around 400K. The results are discussed on the basis of existing models by considering the structural groups present in these glasses.

Anavekar, R. V.; Eraiah, B.

2002-12-01

438

[A study of mechanical properties of orthodontic wires in tension].  

PubMed

Orthodontic forces are applied to the teeth basically by means of different types of orthodontic wires. Knowledge of the mechanical properties of such wires are very helpful to the clinician in design and application of optimal force systems during orthodontic treatment. The basic mechanical properties were studied for 17 types of orthodontic wires (all rectangular and of the same size), in tension. Modulus of elasticity (E), yield strength (YS) and maximum elastic strain (Springback) (YS/E) were calculated for each type of wires. Stainless steel wires have demonstrated higher modulus of elasticity (and yield strength) in comparison with wires of nickel-titanium and beta titanium alloys. B-titanium wires showed higher modulus of elasticity than nickel-titanium ones. In addition stainless steel wires were found to have higher values for springback than cobalt-chromium ones and lower values (for the same variable) than nickel-titanium and B-titanium wires. PMID:2129597

Konstantellos, B; Lagoudakis, M; Toutountzakis, N

1990-12-01

439

Slide the wire  

NSDL National Science Digital Library

The animation shows a top view of four wires in a conducting loop and a galvanometer. Determine the direction of the magnetic field, Bz(x), passing through the wires at various postions by click-dragging the black wire back and forth and observing the galvanometer reading.

Wolfgang Christian

440

High-field-seeking Rydberg atoms orbiting a charged wire  

NASA Astrophysics Data System (ADS)

Pulsed supersonic beams of helium atoms in the high-field-seeking 52p Rydberg state have been guided while following helical trajectories in the electrostatic field of a charged wire suspended along the axis of a grounded cylindrical metallic tube. The operation of this electrostatic wire guide for samples in high-field-seeking Rydberg-Stark states has been investigated with dc and pulsed electric potentials applied to the wire while the guided atoms were detected by pulsed electric-field ionization. The acceptance of the guide has been determined through numerical particle trajectory simulations.

Ko, H.; Hogan, S. D.

2014-05-01

441

Phase-Sensing Guidance for Wire-Following Vehicles  

NASA Technical Reports Server (NTRS)

Guidance system for wire-following vehicles tested successfully at speeds exceeding 50 mi/h (80 km/h) on difficult 1 mile (1.6km) course. Unlike previous sensors that compare amplitudes of signals picked up from guide wire, new system compares signal phases. Array of coils is mounted in line along front bumper of vehicle and monitors electromagnetic signal radiating from wire. Guide wire on ground beneath vehicle carrier 6- to 7-kHz alternating current.

Hansen, G. R.

1983-01-01

442

Development of an efficient utility interactive combined wind\\/photovoltaic\\/fuel cell power system with MPPT and DC bus voltage regulation  

Microsoft Academic Search

In this paper, development and simulation of an efficient small-scale centralized dc-bus grid connected hybrid wind\\/photovoltaic\\/fuel cell for supplying power to a low voltage distribution system are presented. The hybrid system consists of wind and photovoltaic as a primary power system. A fuel cell is added as a secondary system to ensure continuous power supply and to take care of

Nabil A. Ahmed; A. K. Al-Othman; M. R. AlRashidi

2011-01-01

443

A Practical Monitoring System for the Structural Safety of Mega-Trusses Using Wireless Vibrating Wire Strain Gauges  

PubMed Central

Sensor technologies have been actively employed in structural health monitoring (SHM) to evaluate structural safety. To provide stable and real-time monitoring, a practical wireless sensor network system (WSNS) based on vibrating wire strain gauges (VWSGs) is proposed and applied to a building under construction. In this WSNS, the data measured from each VWSG are transmitted to the sensor node via a signal line and then transmitted to the master node through a short-range wireless communication module (operating on the Industrial, Scientific, and Medical (ISM) band). The master node also employs a long-range wireless communication module (Code Division Multiple Access—CDMA) to transmit the received data from the sensor node to a server located in a remote area, which enables a manager to examine the measured data in real time without any time or location restrictions. In this study, a total of 48 VWSGs, 14 sensor nodes, and seven master nodes were implemented to measure long-term strain variations of mega-trusses in an irregular large-scale building under construction. Based on strain data collected over a 16-month period, a quantitative evaluation of the construction process was performed to determine the aspects that exhibit the greatest influence on member behavior and to conduct a comparison with numerical simulation results. The effect of temperature stress on the structural elements was also analyzed. From these observations, the feasibility of a long-term WSNS based on VWSGs to evaluate the structural safety of an irregular building under construction was confirmed. PMID:24351640

Park, Hyo Seon; Lee, Hwan Young; Choi, Se Woon; Kim, Yousok

2013-01-01

444

Wire-Guide Manipulator For Automated Welding  

NASA Technical Reports Server (NTRS)

Compact motor drive positions guide for welding filler wire. Drive part of automated wire feeder in partly or fully automated welding system. Drive unit contains three parallel subunits. Rotations of lead screws in three subunits coordinated to obtain desired motions in three degrees of freedom. Suitable for both variable-polarity plasma arc welding and gas/tungsten arc welding.

Morris, Tim; White, Kevin; Gordon, Steve; Emerich, Dave; Richardson, Dave; Faulkner, Mike; Stafford, Dave; Mccutcheon, Kim; Neal, Ken; Milly, Pete

1994-01-01

445

Computer-aided optimization of DC/DC converters for automotive applications  

E-print Network

This paper investigates computer-aided optimization of DC/DC converters, with a focus on converters for dual-voltage automotive electrical systems. A new CAD optimization approach based on Monte Carlo search methods is ...

Neugebauer, Timothy C.

446

Introduction of DC line structures into a superconducting microwave 3D cavity  

NASA Astrophysics Data System (ADS)

We report a technique that can noninvasively add multiple DC wires into a 3D superconducting microwave cavity for electronic devices that require DC electrical terminals. We studied the influence of our DC lines on the cavity performance systematically. We found that the quality factor of the cavity is reduced if any of the components of the electrical wires cross the cavity equipotential planes. Using this technique, we were able to incorporate a quantum dot (QD) device into a 3D cavity. We then controlled and measured the QD transport signal using the DC lines. We have also studied the heating effects of the QD by the microwave photons in the cavity.

Kong, Wei-Cheng; Deng, Guang-Wei; Li, Shu-Xiao; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Guo, Guo-Ping

2015-02-01

447

A survey of the Pseudomonas syringae pv. tomato DC3000 type III secretion system effector repertoire reveals several effectors that are deleterious when expressed in Saccharomyces cerevisiae  

Technology Transfer Automated Retrieval System (TEKTRAN)

The injection of nearly 30 effector proteins by the type III secretion system underlies the ability of Pseudomonas syringae pv. tomato strain DC3000 to cause disease in tomato and other host plants. The search for effector functions is complicated by redundancy within the repertoire and by plant R-g...

448

Impact of the addition of a rotor-mounted damper bar cage on the performance of samarium-cobalt permanent magnet brushless DC motor systems  

Microsoft Academic Search

The impact of the addition of rotor-mounted amortisseur damper bar cages on the performance of permanent magnet brushless DC motors is investigated. Extension of models in previous papers is used to include the effects of the damper bar cage for a 15 hp, 120 V, 6-pole motor system for which ample test data were available. The results obtained in the

T. M. Hijazi; N. A. Demerdash

1988-01-01

449

An ECF sigma factor mediated cell surface signaling system in Pseudomonas syringae pv. tomato DC3000 regulates gene expression in response to heterologous siderophores  

Technology Transfer Automated Retrieval System (TEKTRAN)

The diversity of regulatory systems encoded by bacteria provides an indication of the variety of stresses and interactions that these organisms encounter in nature. We have been investigating how the plant pathogen, Pseudomonas syringae pv. tomato DC3000, responds to iron limitation and have focuse...

450

Design, analysis and limitations of a DC-to-AC converter usable for interface alternative energy sources and energy storage systems with the utility grid  

Microsoft Academic Search

A DC-AC power converter design that can be used to interface any type of alternative energy source or energy storage system with the utility grid is presented. The converter is capable of real and reactive power exchanges between the utility grid and the alternative energy source(s). The control philosophy is very simple and allows for the synthesis of useful harmonics.

Ashim K. Chakravorti; Alexander E. Emanuel

1993-01-01

451

GENOME-WIDE IDENTIFICATION OF PROTEINS SECRETED BY THE HRP TYPE III SECRETION SYSTEM OF PSEUDOMONAS SYRINGAE PV. TOMATO DC3000  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of Pseudomonas syringae pv. tomato DC3000 to be pathogenic on plants is dependent on the Hrp type III protein secretion system and, collectively, the effector proteins translocated into plant cells. A genome wide search for Hrp effectors was performed based on patterns in the N terminal...

452

TOWARDS DRIVE-BY-WIRE AUTOMOBILES  

Microsoft Academic Search

The development of automotive systems shows an increasing integration of electronic sen- sors, microcomputers and actuators for single components, engine, drive-chain, suspensions and brakes. After considering electronic driver assisting systems such as ABS, TCS, ASR, ESP, BA the developments towards drive-by-wire systems with and without mechanical or hydraulic backup are considered. Drive-by-wire systems consist of an operating unit (steering wheel,

Rolf Isermann

2000-01-01

453

Solid modeling of 4-axis wire EDM cut geometry  

Microsoft Academic Search

NC verification has been widely used in milling and turning machining, but the implementation of NC verification for wire electrical discharge machine (wire EDM) has received little attention, made difficult by the characteristics of geometry cut by the thin wire. For an NC verification system, the speed and the accuracy of are two of the most critical issues. In this

Chonglin Liu; Donald M. Esterling

1997-01-01

454

Minicomputers and microprocessors in optical systems; Proceedings of the Seminar, Washington, DC, April 8, 9, 1980  

NASA Astrophysics Data System (ADS)

Spectroscopic applications are considered, taking into account microprocessors in spectroscopic applications of imaging devices, design considerations for a microprocessor-based multipurpose spectral radiometer system, applying a microprocessor-controlled spectral radiometer system to field measurements, a spectral analysis microcomputer, calculator-assisted evaluation of reflectance characteristics of fluorescent films, and a micro-computerized facility for on-line spectroscopic plasma diagnostics. Attention is also given to sensors, control applications, and instruments. Design considerations for a solid-state image sensing system are discussed along with system requirements for computer-aided testing and evaluation of solid-state imaging devices, a computer-controlled laser bore scanner, a microprocessor-controlled photodetector test console, an experimental image alignment system, a microcomputer system for controlling an infrared scanning camera, closed-loop active optical system control, a fully integrated microprocessor-controlled surveying instrument, and a new approach to high-precision phase measurement interferometry.

Koliopoulos, C. L.; Zweibaum, F. M.

1980-01-01

455

Failure detection and control-system reconfiguration: Past, present, and future. [F-8 fly-by-wire aircraft  

NASA Technical Reports Server (NTRS)

The history of failure detection and redundancy management in aircraft applications is reviewed. To date, techniques related to that subject have been based mainly on hardware duplication of like components with failure monitoring and switchover or averaging for redundancy management. Specific examples of these techniques are discussed as they have been applied to the NASA F-8 Digital Fly-by-Wire aircraft and are to be applied to the space shuttle vehicle in the near future.

Montgomery, R. C.

1975-01-01

456

Trust-by-Wire in Packet-Switched IPv6 Networks: Tools and FPGA Prototype for the IPclip System  

Microsoft Academic Search

This demonstration shows the hardware prototype of the IPclip (IP calling line identification presentation) mechanism for IPv6 networks. IPclip is a mechanism, which provides Trust-by-Wire in IP-based networks by adding trustworthy location information to IP packets. It is implemented on an FPGA development board and configurable at runtime via a graphical configuration tool. We show IPclip's basic functionality in a

Peter Danielis; Stephan Kubisch; Harald Widiger; Jens Rohrbeck; Vladyslav Altman; Jan Skodzik; Dirk Timmermann; Thomas Bahls; Daniel Duchow

2009-01-01

457

Beam tests of WPC-8 and WPC-9 prototypes of the wire pad chambers for the LHCb muon system  

E-print Network

Two new prototypes, WPC-8 and WPC-9, of the Wire Pad Chambers have been constructed at PNPI. The design of these double-gap wire chambers was similar to the previously tested WPC-7 prototype with one important difference: the anode wire planes were electrically independent, which allows to operate the new prototypes either in the double-gap or in the single-gap modes. The prototypes have been tested in the T11 beam at CERN, and this report presents the results of the tests. As in the previous tests, the PNPI front-end electronics based on the discrete elements was used in the read out channels. In addition, a new option of the FE electronics based on the SONY chip has been developed (SONY++) with an active adapter at the input of the chip allowing to reduce the input impedance and the width of the shaped signals. The SONY++ option was tested with the WPC-9 prototype with very satisfactory results. The performance proved to be identical to that with the PNPI FE electronics.

Bochin, B; Lazarev, V A; Sagidova, N; Spiridenkov, E M; Vorobiev, A P; Vorobyov, A

2001-01-01

458

Derivation of UPFC DC load flow model with examples of its use in restructured power systems  

Microsoft Academic Search

The unified power flow controller (UPFC) integrates properties of both shunt and series compensations, and can effectively alter power system parameters in a way that increases power transfer capability and stabilizes the system. The paper presents an approximate model for power flow studies that takes into consideration modeling of lossless UPFC-embedded transmission lines including the effect of line charging susceptance.

Muwaffaq I. Alomoush

2003-01-01

459

Electrical power distribution system (HV270DC), for application in more electric aircraft  

Microsoft Academic Search

In the new designs of military aircraft and unmanned aircraft there is a clear trend towards increasing demand of electrical power. This fact is mainly due to the replacement of mechanical, pneumatic and hydraulic equipments by partially or completely electrical systems. Generally, use of electrical power onboard is continuously increasing within the areas of communications, surveillance and general systems, such

D. Izquierdo; R. Azcona; F. J López del Cerro; C. Fernandez; B. Delicado

2010-01-01

460

Distribution of the traction return current in AC and DC electric railway systems  

Microsoft Academic Search

The problem of the determination of the real distribution of the return current in electric railway traction systems is considered. One or more conductors (depending on the specific supply system) are purposely set up to carry the traction return current flowing from the rolling stock axles back to the supply (i.e., substation); yet, part of the return current flows through

Andrea Mariscotti

2003-01-01

461

Azimuthal wire motion and ablation dynamics in z-pinches  

NASA Astrophysics Data System (ADS)

This dissertation describes theoretical, simulation, and experimental work to study ablation dynamics and azimuthal 'clumping' of wires in multi-wire z-pinch arrays. First, a resistive-inductive model of discrete filamentary conductors is developed to model wires in multi-wire z-pinches. These equations have been shown to decrease computation times over similar models in literature by as much as 5 orders of magnitude. From these new equations, a simulation code called REIN (REsistive-INductive) was developed to simulate discrete wire arrays. REIN simulations revealed that wires 'clumped' azimuthally when an initial random azimuthal perturbation was placed on the wire positions. Theory was developed to describe the observed clumping. The fastest growing clumping mode was found to be the pairing of neighboring wires (pi-mode). Experiments were conducted by the author on the COBRA accelerator (1 MA, 100 ns risetime) at Cornell University to look for azimuthal wire clumping in closely spaced wires. Radiography of wire cores did not demonstrate azimuthal wire clumping. However, based on the lack of motion, the major conclusion of the experiment is that less than 7% of the total current was flowing in the wire cores. Another calculation indicated that for wire cores to remain unvaporized by resistive heating, less than 1% of the current could have flowed in the cores. The other 93--99% of the current must therefore have flowed in the coronal plasma. Results also indicated presence of axial non-uniform ablation. Experiments performed at the University of Michigan on the MIZ-3 (9-10 kA, 400 ns risetime) and MIZ-4 (18 kA, 150 ns risetime) facilities are also described. On MIZ-4, plasma electron temperatures of ablated 30 mum Al wires were measured by emission spectroscopy to be 1.5-2 eV. Comparing results to previous experiments, it is observed that electron temperature scales very weakly with current (more than 10 times increase in current amplitude resulted in less than 2 times increase in electron temperature). On MIZ-3, more intense optical emission from wires preheated with DC currents indicated greater energy deposition than in slightly preheated wires.

Strickler, Trevor S.

462

Electronic transport in inhomogeneous quantum wires.  

SciTech Connect

We study the transport properties of a long non-uniform quantum wire where the electron-electron interactions and the density vary smoothly at large length scales. We show that these inhomogeneities lead to a finite resistivity of the wire, due to a weak violation of momentum conservation in the collisions between electrons. Estimating the rate of change of momentum associated with non-momentum-conserving scattering processes, we derive the expression for the resistivity of the wire in the regime of weakly interacting electrons and find a contribution linear in temperature for a broad range of temperatures below the Fermi energy. By estimating the energy dissipated throughout the wire by low-energy excitations, we then develop a different method for deriving the resistivity of the wire, which can be combined with the bosonization formalism. This allows us to compare our results with previous works relying on an extension of the Tomonaga-Luttinger model to inhomogeneous systems.

Rech, J.; Matveev, K. A.; Materials Science Division

2008-04-23

463

Wiring Damage Analyses for STS OV-103  

NASA Technical Reports Server (NTRS)

This study investigated the Shuttle Program s belief that Space Transportation System (STS) wiring damage occurrences are random, that is, a constant occurrence rate. Using Problem Reporting and Corrective Action (PRACA)-derived data for STS Space Shuttle OV-103, wiring damage was observed to increase over the vehicle s life. Causal factors could include wiring physical deterioration, maintenance and inspection induced damage, and inspection process changes resulting in more damage events being reported. Induced damage effects cannot be resolved with existent data. Growth analysis (using Crow-AMSAA, or CA) resolved maintenance/inspection effects (e.g., heightened awareness) on all wire damages and indicated an overall increase since Challenger Return-to-Flight (RTF). An increasing failure or occurrence rate per flight cycle was seen for each wire damage mode; these (individual) rates were not affected by inspection process effects, within statistical error.

Thomas, Walter, III

2006-01-01

464

Thin wire pointing method  

NASA Technical Reports Server (NTRS)

A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

Green, G.; Mattauch, R. J. (inventors)

1983-01-01

465

Efficiency estimation in digitally-controlled dc-dc buck converters based on single current sensing  

Microsoft Academic Search

This paper proposes an efficiency estimator for dc-dc buck converters suitable for on-chip integration in the digital IC controller. The proposed solution is tailored for distributed power architectures, where the on-line efficiency measurement or estimation of each dc-dc converter is useful in order to perform a system power management and to monitor the status of each point of load (POL)

S. Saggini; W. Stefanutti; P. Mattavelli; A. Carrera

2008-01-01

466

Comparing DC-DC converters for power management in hybrid electric vehicles  

Microsoft Academic Search

The design of DC-DC converters for power electronic interfaces in power management systems for hybrid electric vehicle (HEV) is a very challenging task. To this end, this paper presents an analysis, design, and comparison study of several bi-directional non-isolated DC-DC converter topologies that could be considered potential candidates for the power electronic interface of HEV energy\\/power sources, in particular an

R. M. Schupbach; J. C. Balda

2003-01-01

467

Sintered wire annode  

DOEpatents

A plurality of high atomic number wires are sintered together to form a porous rod that is parted into porous disks which will be used as x-ray targets. A thermally conductive material is introduced into the pores of the rod, and when a stream of electrons impinges on the sintered wire target and generates x-rays, the heat generated by the impinging x-rays is removed by the thermally conductive material interspersed in the pores of the wires.

Falce, Louis R. (Surprise, AZ); Ives, R. Lawrence (Saratoga, CA)

2007-12-25

468

Circular photogalvanic effect induced by near-infrared radiation in InAs quantum wires patterned quasi-two-dimensional electron system  

SciTech Connect

In this letter we investigated the InAs/InAlAs quantum wires (QWRs) superlattice by optically exciting the structure with near-infrared radiation. By varying the helicity of the radiation at room temperature we observed the circular photogalvanic effect related to the C{sub 2v} symmetry of the structure, which could be attributed to the formation of a quasi-two-dimensional system underlying in the vicinity of the QWRs pattern. The ratio of Rashba and Dresselhaus terms shows an evolution of the spin-orbit interaction in quasi-two-dimensional structure with the QWR layer deposition thickness.

Jiang Chongyun; Chen Yonghai; Ma Hui; Yu Jinling; Liu Yu [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, 100083 Beijing (China)

2011-06-06

469

Wire-inhomogeneity detector  

DOEpatents

A device for uncovering imperfections in electrical conducting wire, particularly superconducting wire, by detecting variations in eddy currents. Eddy currents effect the magnetic field in a gap of an inductor, contained in a modified commercial ferrite core, through which the wire being tested is passed. A small increase or decrease in the amount of conductive material, such as copper, in a fixed cross section of wire will unbalance a bridge used to measure the impedance of the inductor, tripping a detector and sounding an alarm.

Gibson, G.H.; Smits, R.G.; Eberhard, P.H.

1982-08-31

470

Nano-storage wires.  

PubMed

We report the development of "nano-storage wires" (NSWs), which can store chemical species and release them at a desired moment via external electrical stimuli. Here, using the electrodeposition process through an anodized aluminum oxide template, we fabricated multisegmented nanowires composed of a polypyrrole segment containing adenosine triphosphate (ATP) molecules, a ferromagnetic nickel segment, and a conductive gold segment. Upon the application of a negative bias voltage, the NSWs released ATP molecules for the control of motor protein activities. Furthermore, NSWs can be printed onto various substrates including flexible or three-dimensional structured substrates by direct writing or magnetic manipulation strategies to build versatile chemical storage devices. Since our strategy provides a means to store and release chemical species in a controlled manner, it should open up various applications such as drug delivery systems and biochips for the controlled release of chemicals. PMID:23859333

Lee, Dong Jun; Kim, Eunji; Kim, Daesan; Park, Juhun; Hong, Seunghun

2013-08-27

471

The Use of Software Agents for Autonomous Control of a DC Space Power System  

NASA Technical Reports Server (NTRS)

In order to enable manned deep-space missions, the spacecraft must be controlled autonomously using on-board algorithms. A control architecture is proposed to enable this autonomous operation for an spacecraft electric power system and then implemented using a highly distributed network of software agents. These agents collaborate and compete with each other in order to implement each of the control functions. A subset of this control architecture is tested against a steadystate power system simulation and found to be able to solve a constrained optimization problem with competing objectives using only local information.

May, Ryan D.; Loparo, Kenneth A.

2014-01-01

472

Inspection of fine wires simplified by capillary tube wire holder  

NASA Technical Reports Server (NTRS)

Capillary tube wire holder provides a mount for fine wires for photomicrographs. The holder is mounted in a stainless steel tube and cast in a transparent casting material. It protects and permits easy location of the wire.

Raphael, H. A.

1965-01-01

473

Semantic Internetworking of Sensor Systems1 Ke Wang, Salma Abu Ayyash, Thomas D.C. Little  

E-print Network

a reality, mechanisms that allow data exchange between sensor systems deployed at different times with one another to increase capacity and/or performance may be prevented from doing so due sensor networks include: soil condition monitoring for agricultural purposes, habitat monitoring

Little, Thomas

474

Optimized restoration of combined ac\\/dc shipboard power systems including distributed generation and islanding techniques  

Microsoft Academic Search

Reconfiguration involves changing the status (OFF\\/ON) of switches, and reconfiguration for restoration involves changing the switch status to maximize the supply to loads that are left unsupplied after fault removal. Shipboard Power Systems (SPS) need automated reconfiguration for restoration schemes to restore vital loads quickly and efficiently in order to improve fight-through and survivability capabilities. The restoration in this paper

Sarika Khushalani; Jignesh Solanki; Noel Schulz

2008-01-01

475

Wire Array Photovoltaics  

NASA Astrophysics Data System (ADS)

Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction arrays. These devices offer potential efficiencies of 34%, as demonstrated through an analytical model and optoelectronic simulations. SiGe and Ge wires were fabricated via chemical-vapor deposition and reactive ion etching. GaAs was then grown on these substrates at the National Renewable Energy Lab and yielded ns lifetime components, as required for achieving high efficiency devices.

Turner-Evans, Dan

476

An efficient plant regeneration system for Mucuna pruriens L. (DC.) using cotyledonary node explants  

Microsoft Academic Search

Summary  The purpose of this study was to develop an efficient micropropagation system for Mucuna pruriens, an important medicinal plant in India. A range of cytokinins was investigated for multiple shoot regeneration with cotyledonary\\u000a node explants from 7-d-old aseptic seedlings. Of all the cytokinins, 6-benzyladenine (BA), kinetin (KIN) and 2-isopentenyl\\u000a adenine (2-iP) tested in Murashige and Skoog medium (MS), BA was

M. Faisal; I. Siddique; M. Anis

2006-01-01

477

Suitable single-phase to three-phase AC-DC-AC power conversion system  

Microsoft Academic Search

This paper presents a single-phase to three-phase power conversion system with parallel rectifier and series inverter to cope with single-phase to three-phase asymmetry. Such converter guarantees both reduction in the input current processed by rectifier circuit and reduction of the output voltage processed by inverter circuit. It is worth to mention that, in spite of proposing a topology with features

E. C. dos Santos; N. Rocha; C. B. Jacobina; R. S. Macena

2012-01-01

478

Precise DC current sensors  

Microsoft Academic Search

Three novel DC current sensors are described. Portable 40 A DC current clamps have resolution of 1 mA and high immunity to unclamped currents and external fields. AC\\/DC comparator with amorphous core may serve for precise measurement of DC currents with AC component up to 1 kHz. Magnetoresistive sensor field has limited accuracy but potential bandwidth from DC to 1

P. Ripka; P. Kejik; P. Kaspar; K. Draxler

1996-01-01

479

Wire Weight with Housing  

USGS Multimedia Gallery

Wire weight is lowered to water surface to measure stage at a site. Levels are made to the wire weights elevation from known benchmarks to ensure correct readings. In the background there is housing protected with dikes along the Missouri River in Mandan, ND....

480

Imagination Visualized in Wire.  

ERIC Educational Resources Information Center

Describes an art lesson achieved with a Very Special Artist (VSA) in residence for sixth- and seventh-grade students in which they created wire sculptures. Discusses how the VSA taught the students. Includes a list of art materials and characteristics of wire. (CMK)

Skophammer, Karen

2003-01-01