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1

Topology for Current Balancer with Half-Bridge Inverters in Single-Phase Three-Wire Distribution Systems with DC-Capacitor-Voltage Balancer  

NASA Astrophysics Data System (ADS)

This paper proposes a new topology for a current balancer with half-bridge inverters in single-phase three-wire distribution systems with a three-leg inverter. Two half-bridge inverters are connected to the sources. The midpoint of two capacitors on the DC-side is connected to a neutral line. The two half-bridge inverters perform a current balancer for single-phase three-wire distribution systems by exchanging the active and reactive power on the each feeder through the two DC-capacitors. The third-leg performs a DC-capacitor-voltage balancer for the two DC-capacitors connected to the half-bridge inverters. Thus, balanced source voltages and currents are obtained on the secondary-side on the pole-mounted distribution transformer with balanced DC-capacitor voltages. The basic principle of the proposed current balancer is discussed in detail, and then, confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested. Experimental results show that balanced source voltages and currents are obtained on the secondary-side on the pole-mounted distribution transformer with balanced DC-capacitor voltages.

Baba, Yusuke; Sugahara, Kazuya; Okamoto, Masayuki; Hiraki, Eiji; Tanaka, Toshihiko

2

A Constant DC Voltage Control Based Strategy for the Current Balancer in Single-Phase Three-Wire Secondary Distribution Systems  

NASA Astrophysics Data System (ADS)

This paper deals with applying the constant dc voltage control based algorithm to the current balancer in single-phase three-wire secondary distribution systems. The power flows into a three-leg inverter, which performs the current balancer, are discussed, and then we show that only the reactive power flows into the three-leg inverter. This demonstrates that the required-capacity of the dc capacitor can be reduced as compared to that of the active power quality compensator used in the electrified railways. This reduced-capacity dc capacitor results in the rapid and stable balancing. The basic principle of the proposed method is discussed in detail, and then confirmed by digital computer simulation. Digital computer simulation results demonstrate that the balanced source currents with unity power factor are obtained remaining the unbalanced load currents conditions.

Fukui, Hirokazu; Hiraki, Eiji; Tanaka, Toshihiko

3

A Constant DC-Capacitor Voltage Control Based Strategy for Current Balancer in Single-Phase Three-Wire Distribution Systems  

NASA Astrophysics Data System (ADS)

This paper proposes a strategy based on constant dc-capacitor voltage control for a current balancer in single-phase three-wire distribution systems. The proposed control strategy involves the use of only the constant dc-capacitor voltage control block commonly used in active power conditioners for the calculation of the compensation current. No calculation block is required to obtain the reactive and unbalanced-active components. Thus, we provide the simplest possible control strategy for the current balancer. The basic principle of the proposed control method is discussed in detail and its validity, which is confirmed by a digital computer simulation using PSIM software, is shown. A prototype experimental model is constructed and tested. Experimental results demonstrate that balanced source currents with a power factor of unity are obtained on the secondary side of a pole-mounted distribution transformer while unbalanced load current conditions with a lagging power factor are retained.

Baba, Yusuke; Okamoto, Masayuki; Hiraki, Eiji; Tanaka, Toshihiko; Lee, Seong Ryong

4

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

5

A 37 channel DC SQUID magnetometer system  

Microsoft Academic Search

A 37-channel DC SQUID magnetometer system has been built for biomagnetic studies. The SQUID loop of each magnetometer serves as the active sensing element, thereby eliminating the need for flux coupling circuits. The magnetometers are located ≃3 cm above the outer dewar bottom. The SQUIDs are directly coupled to a highly simplified readout electronics using only five wires per channel;

H. Koch; R. Cantor; D. Drung; S. N. Erne; K. P. Matthies; M. Peters; T. Ryhanen; H. J. Scheer; H. D. Hahlbohm

1991-01-01

6

Robust 300 C wire insulation system  

NASA Technical Reports Server (NTRS)

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system that is capable of continuous operation at 300 C. The system is to possess a combination of superior electrical (AC or DC), mechanical, and physical properties over the KAPTON (trademark) derived insulations described in MIL-W-81381 and those hybrid constructions identified in Air Force contract F33615-89-C-5606, commonly known as TKT constructions.

Nairus, John G.

1994-01-01

7

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

8

A 37 channel dc SQUID magnetometer system  

SciTech Connect

This paper reports on a 37 channel dc SQUID magnetometer system built for biomagnetic studies. The SQUID loop of each magnetometer serves as the active sensing element, thereby eliminating the need for flux coupling circuits. The magnetometers are located {approx equal}3 cm above the outer dewar bottom. The SQUIDs are directly coupled to a highly simplified read-out electronics using only 5 wires per channel; no helium temperature impedance matching circuits are required. Each channel can be independently inserted into or remove from the dewar.

Koch, H.; Cantor, R.; Drung, D.; Erne, S.N.; Matthies, K.P.; Peters, M.; Ryhanen, T.; Scheer, H.J.; Hahlbohn, H.D. (Physikalisch-Technische Bundesanstalt, Institut Berlin, Abbestr. 10-12, D-1000 Berlin (DE))

1991-03-01

9

Illumination system for wire bonding inspection.  

PubMed

A novel lighting system was devised for 3D defect inspection in the wire bonding process. Gold wires of 20 microm in diameter were bonded to connect the integrated circuit (IC) chip with the substrate. Bonding wire defects can be classified as 2D type and 3D type. The 2D-type defects include missed, shifted, or shorted wires. These defects can be inspected from a 2D top-view image of the wire. The 3D-type bonding wire defects are sagging wires, and are difficult to inspect from a 2D top-view image. A structured lighting system was designed and developed to facilitate all 2D-type and 3D-type defect inspection. The devised lighting system can be programmed to turn the structured LEDs on or off independently. Experiments show that the devised illumination system is effective for wire bonding inspection and will be valuable for further applications. PMID:17279128

Perng, Der-Baau; Chou, Cheng-Chuan; Lee, Shu-Ming

2007-02-20

10

Calculation of ozone generation by positive dc corona discharge in coaxial wire-cylinder reactors  

SciTech Connect

A theoretical equation has been derived in this paper for calculation of ozone generation by positive dc corona discharge in coaxial wire-cylinder reactors. The derived equation has been based on the theories of the positive dc coronas reported in the literature and extended to account the ozone destruction within the corona discharge plasma generated in the reactor. The equation has been investigated with experimental results for ozone generated in a coaxial wire-cylinder reactor under different discharge conditions. The reactor was stressed with a positive dc voltage and fed by dry air flowing with constant rates at atmospheric pressure and room temperature. The theoretical results calculated by the derived equation have shown good agreement with the experimental results over the whole range of the investigated parameters. Subsequently, the derived equation is valid to predict the ozone concentration generated in the investigated reactor under any discharge conditions.

Yehia, Ashraf [Department of Physics, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

2007-01-15

11

Wire-rope emplacement of diagnostics systems  

SciTech Connect

The study reported here was initiated to determine if, with the Cable Downhole System (CDS) currently under development, there is an advantage to using continuous wire rope to lower the emplacement package to the bottom of the hole. A baseline design using two wire ropes as well as several alternatives are discussed in this report. It was concluded that the advantages of the wire-rope emplacement system do not justify the cost of converting to such a system, especially for LLNL's maximum emplacement package weights.

Burden, W.L.

1982-05-07

12

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

13

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

14

Fuse protection of DC systems  

SciTech Connect

Selecting a fuse that will provide the required protection for a direct current (DC) application is not as simple as it may sound. Alternating current (AC) circuits are more common than DC circuits; therefore, more is known about how electrical components, including overcurrent protective devices, operate on AC than is known about their operation on DC. The concept of DC is so simple that there is a tendency to assume that choosing overcurrent protection for DC applications is also simple. This is not the case. To correctly select a fuse for a DC application, the DC capabilities of the fuse must be known as well as the critical circuit parameters and the overcurrent conditions under which the fuse is expected to operate. Most fuse data relates directly to AC applications not DC. Furthermore, DC circuit parameters vary widely from application to application and affect fuse performance significantly. Representing fuse performance for the large envelope of DC circuit parameters is not realistic. Some AC data can be correctly used for DC once there is a thorough understanding of what this data represents. The intent of this paper is to give the reader a better understanding of DC capabilities of fuses and the critical DC circuit parameters that must be known to select appropriate fuses for DC applications. The tools presented may be directly applied to real life situations and include step by step examples.

Cline, H.C. [Gould Shawmut, Newburyport, MA (United States)

1995-09-01

15

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

16

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

17

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

18

Neutral Current of an Edison Wire System  

NSDL National Science Digital Library

This is an object learning lesson, created by Terry Bartelt of the Wisconsin Online Resource Center, on neutral current of an Edison wire system. The employment of Flash allows users to interact with the presentation. Overall, this is a nice introduction to this specific topic.

Bartelt, Terry L. M.

19

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&D support #12;Superconductivity for Electric Systems Annual Peer Review Washington, DC ­ July 27-29, 2004 Commercial 2 G wire Mat Sci knowledge learning Quality, yield cost reduction #12;Superconductivity

20

USAF/WL robust 300 C wire insulation system program status  

NASA Technical Reports Server (NTRS)

The objective of this program is to identify, develop, and demonstrate an optimum wire insulation system capable of continuous operation at 300 C which possesses a combination of superior electrical (AC or DC), mechanical, and physical properties over Kapton derived insulations described in MIL-W-81381 and those hybrid materials commonly known as TKT constructions.

Wong, Wing

1995-01-01

21

Development of an Ultrahigh Speed Robot FALCON Using Wire Drive System  

Microsoft Academic Search

High speed robots are an important component of modern assembly operations. In this paper, we describe the development of an ultrahigh speed robot named FALCON (Fast Load Conveyance), based on a wire driven parallel manipulation system. It achieves peak accelerations of up to 43G and maximum velocities of 13 m\\/s, even if considerably small DC motors (60W) are used. Due

Sadao Kawamura; W. Choe; S. Tanaka; Shunmugham R. Pandian

1995-01-01

22

Anti-slipping system improves wire saw performance  

NASA Technical Reports Server (NTRS)

System prevents wire saw slippage by providing sufficient friction to turn idler spools even when turns of wire on spools do not provide sufficient friction. Low cost system is easily applied to existing equipment.

Gallo, E. A.

1971-01-01

23

A fractional order model for steer-by-wire systems  

Microsoft Academic Search

The steer by wire system for vehicles has attracted much attention in recent years. Steer by wire systems provide many benefits in terms of functionality and at the same time present significant challenges too. It is essential to investigate the stability of steer by wire systems using a more sophisticated model rather than common approximated models. Fractional order modeling offers

F. Tahami; H. Afshang

2009-01-01

24

Embedded Automotive System Development Process Steer-By-Wire System  

E-print Network

developers by providing a common environment for graphical specification and analysis. In this process model in the loop. Integral Components Most software standards require traceability of requirementsEmbedded Automotive System Development Process Steer-By-Wire System Joachim Langenwalter

Paris-Sud XI, Université de

25

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

E-print Network

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

Rincon-Mora, Gabriel A.

26

Life prediction of aging aircraft wiring systems  

NASA Technical Reports Server (NTRS)

The program goal is to develop a computerized life prediction model capable of identifying present aging progress and predicting end of life for aircraft wiring. A summary is given in viewgraph format of progress made on phase 1 objectives, which were to identify critical aircraft wiring problems; relate most common failures identified to the wire mechanism causing the failure; assess wiring requirments, materials, and stress environment for fighter aircraft; and demonstrate the feasibility of a time-temperature-environment model.

Slenski, George

1995-01-01

27

Expandable multiterminal DC systems based on voltage droop  

SciTech Connect

This paper introduces a decentralized control scheme for the parallel connection of multiple rectifiers feeding a dc network with numerous inverters. The coordination of multiple HV dc systems without explicit communication is accomplished by the use of dc-side voltages as a droop mechanism. The dc side voltage serves the role of frequency in an ordinary ac system. The approach is most suitable to superconducting dc systems and to dc systems that span small distances and where voltage is relatively uniform throughout the dc system. This paper presents the concept in the context of a high capacity superconducting 10 KV urban infeed.

Johnson, B.K. (Univ. of Idaho, Moscow, ID (United States)); Lasseter, R.H.; Alvarado, F.L. (Univ. of Wisconsin, Madison, WI (United States)); Adapa, R. (Electric Power Research Inst., Palo Alto, CA (United States))

1993-10-01

28

Catalog of DC Appliances and Power Systems  

E-print Network

Room Air Conditioners Security Systems Solar Water Heatersor more 200W solar panels)[9]. Table 2. DC air-conditioners,Air Conditioners Geothermal Heat Pumps Lighting-Incandescent Lighting-Fluorescent Lighting-Reflector Lighting-Torchiere Electric Other Electric Water Heaters Solar

Garbesi, Karina

2012-01-01

29

Generator-battery dc power supply system  

Microsoft Academic Search

A generator-battery dc power supply system comprises a plurality of sub-systems each including a battery and a temperature sensor sensing the temperature of the battery and controlling the generator regulating means to decrease the generator output voltage in response to an increase in the sensed battery temperature, to thereby prevent overheating of the battery by over-charging same. The system further

1983-01-01

30

An Evaluation of Old Armored Cables in Building Wiring Systems  

Microsoft Academic Search

Armored cable has been used in building wiring systems since the early 1900s and remains an accepted wiring method today.\\u000a The original product developed in the early 1900s and that which is commercially available today have significant differences\\u000a in construction and performance. Likewise the demand and expectation of building wiring systems has changed. This paper explores\\u000a some of those differences

John E. Sleights

2011-01-01

31

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-in ORNL-AMSC CRADA: Development of 2G YBCO-RABiTS Wires #12;Superconductivity for Electric Systems Annual Penetration) Form ­ Fit ­ Function replacement for BSCCO #12;Superconductivity for Electric Systems Annual

32

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 of the system. Keywords-Ethernet Control System(ECS); Embedded Linux; Delay; DC Motor I. INTRODUCTION

Paris-Sud XI, Université de

33

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

34

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

35

14 CFR 121.1111 - Electrical wiring interconnection systems (EWIS) maintenance program.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Electrical wiring interconnection systems (EWIS...Safety Improvements 121.1111 Electrical wiring interconnection systems (EWIS...includes inspections and procedures for electrical wiring interconnection systems...

2014-01-01

36

14 CFR 121.1111 - Electrical wiring interconnection systems (EWIS) maintenance program.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Electrical wiring interconnection systems (EWIS...Safety Improvements 121.1111 Electrical wiring interconnection systems (EWIS...includes inspections and procedures for electrical wiring interconnection systems...

2010-01-01

37

Plasmon hybridization in parallel nano-wire systems  

SciTech Connect

We apply the plasmon hybridization method to a double-nano-wire system, providing a simple and intuitive description of the plasmon excitations in the system. We apply the two-center cylindrical coordinate system for mathematical convenience and find an explicit form of the surface plasmon oscillations, in terms of the interaction between the bare plasmon modes of the individual surfaces of the nano-wires. We present numerical results to display how the plasmon excitations of the system depend on nano-wire separation when there is no angular momentum transfer, i.e., when m = 0.

Moradi, Afshin [Department of Nano Science, Kermanshah University of Technology, Kermanshah 67178-63766 (Iran, Islamic Republic of) and Department of Nano Science, Institute for Studies in Theoretical Physics and Mathematics (IPM), Tehran 19395-5531 (Iran, Islamic Republic of)

2011-06-15

38

Electric Field Wire Boom System and instrument for CubeSats  

NASA Astrophysics Data System (ADS)

The viability of CubeSats as meaningful platforms for observing the upper atmosphere depends upon the development of suitable scientific instrumentation. One of the most fundamental parameters to observe in the space environment is the electric fields which drive the motions of the plasma in the ionosphere and magnetosphere. A well known technique for observing electric fields is the double probe with sensors deployed several meters from the space vehicle. A compact wire boom system, deploying sensors from opposite sides of a spinning CubeSat has been developed at Utah State University. We present the development of a 10 meter tip-to-tip wire boom system to deploy four 1-cm spherical double probe sensors. The wire boom mechanism consists of a spool which is actuated with a small non-magnetic, piezoelectric motor, to control deployment. The wire boom and electric field instrument is 1.25cm high and fits a standard 10 x10 cm CubeSat cross section. The spherical sensors at the end of the wire booms are gold plated to minimize geometric work function dissimilarities and to provide surface electrical stability. We present an analysis of the expected performance and lifetime of this boom in low Earth orbit. The proposed design permits the measurement of the two-dimensional DC-electric field determined only by the spacecraft velocity and the instrument sampling rate.

Stromberg, E. M.; Burr, S.; Hui, D.; Swenson, C.

2009-12-01

39

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

40

Wire rope research and logging. [Skyline and dragline systems  

SciTech Connect

The various factors affecting the service life of wire ropes in skyline and dragline systems are discussed: design, geometry, sheave geometry, wear and lubrication, sheave hardness, pickup of small rocks, etc. (DLC)

Morgenstern, M.H.

1981-01-01

41

Strain sensing systems tailored for tensile measurement of fragile wires  

NASA Astrophysics Data System (ADS)

Fundamental stress versus strain measurements were completed on superconducting Nb3Sn wires within the framework of IEC/TC90 and VAMAS/TWA16. A key task was the assessment of sensing systems regarding resolution, accuracy, and precision when measuring Young's modulus. Prior to actual Nb3Sn wire measurements metallic wires, consisting of copper and stainless steel having diameters similar to the Nb3Sn wire, were extensively investigated with respect to their elastic line properties using different types of extensometers. After these calibration tests Nb3Sn wire measurements of different companies resulted in several important facts with respect to total size and weight of the used extensometers. The size could be correlated to the initial stage of stress versus strain behaviour. In fact, the effect of wire curls resulting from the production line had a profound effect on Young's modulus measurements. Within this context, the possibility of determining Young's modulus from unloading compliance lines in the plastic regime of the stress-strain curve was considered. The data obtained using this test methodology were discussed under consideration of the composite nature of Nb3Sn wire. In addition, a non-contacting sensing system based on a double-beam laser extensometer was used to investigate the potential of this new sensing system.

Nyilas, Arman

2005-12-01

42

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

43

Wired Remote Meter Reading System Based on Fieldbus  

Microsoft Academic Search

The paper introduces a kind of wired remote meter reading system based on fieldbus in residential districts. In the thesis, the scheme consists of singlechip AT89C51 and CAN-controller SJA1000 as hardware, and interface-program as software. The system solutions are practicality proved in application, with high automation and strong anti-jamming. It can be for reference to similar plans. Keywords-CAN bus;singlechip;wired remote

Ming Zhao

2011-01-01

44

SQUID Amplifier System for Vibrating Wire Resonators  

Microsoft Academic Search

We describe a simple coupling scheme of superconducting vibrating wire resonators to a SQUID amplifier for achieving supreme signal to noise characteristics. Our construction resulted in a gain factor near 108?0\\/V at 1kHz with an amplifier noise level of about 20 ??0\\/\\u000a

J. Martikainen; J. T. Tuoriniemi

2001-01-01

45

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

SciTech Connect

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 served as a vehicle for further evaluation of a ringing-bypass valve dc interrupter that had been previously designed in work related to the ac/dc conversion system used here. The microprocessor control techniques described here are applicable to most energy conversion systems where a dc power source exchanges energy with an ac network via line-commutated converters. 4 refs., 33 figs.

Kovalsky, L.J.; Putkovich, R.P.

1982-12-20

46

Analysis and Design of Bidirectional DC-DC Converter in Extended Run Time DC UPS System Based on Fuel Cell and Supercapacitor  

Microsoft Academic Search

In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dc converter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The delivered power and peak current are analyzed and calculated. The key parameters of the bi-directional dc-dc converter,

Zhe Zhang; Ole C. Thomsen; Michael A. E. Andersen; Jacob D. Schmidt; Henning R. Nielsen

2009-01-01

47

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

48

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

49

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

50

DC isolation and protection system and circuit  

NASA Technical Reports Server (NTRS)

A precision analog electronic circuit that is capable of sending accurate signals to an external device that has hostile electric characteristics, including the presence of very large common mode voltages. The circuit is also capable of surviving applications of normal mode overvoltages of up to 120 VAC/VDC for unlimited periods of time without damage or degradation. First, the circuit isolates the DC signal output from the computer. Means are then provided for amplifying the isolated DC signal. Further means are provided for stabilizing and protecting the isolating and amplifying means, and the isolated and amplified DC signal which is output to the external device, against overvoltages and overcurrents.

Wagner, Charles A. (Inventor); Kellogg, Gary V. (Inventor)

1991-01-01

51

NASA/BAE SYSTEMS SpaceWire Effort  

NASA Technical Reports Server (NTRS)

This paper discusses the state of the NASA and BAE SYSTEMS developments of SpaceWire. NASA has developed intellectual property that implements SpaceWire in Register Transfer Level (RTL) 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 Spaceflight worthy 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 on their .25micron 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 drivers/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 that works end-to-end. This layer needs to be implemented in hardware to prevent bottlenecks.

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

2003-01-01

52

Dead beat control of DC chopper system with nonlinear load  

Microsoft Academic Search

Two-parameter deadbeat control is applied to the current control of a DC chopper system with lamp load. The two-parameter deadbeat control of the DC current is achieved using a single-chip digital signal processor (DSP). The control program for the DSP has a short computation time. In the actual system, the robustness against the change of controlled system parameter is confirmed

Eiji YAMADA; M. Tsuji; K. Izumi; M. Tanimoto; J. Oyama

1991-01-01

53

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

54

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

55

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

56

DC motor proportional control system for orthotic devices  

NASA Technical Reports Server (NTRS)

Multi-channel proportional control system for operation of dc motors for use with externally-powered orthotic arm braces is described. Components of circuitry and principles of operation are described. Schematic diagram of control circuit is provided.

Blaise, H. T.; Allen, J. R.

1972-01-01

57

New DCDC 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

58

Magnetoimpedance effect of the Ni80Fe20/Cu composite wires: The influence of DC current imposed on the Cu base  

NASA Astrophysics Data System (ADS)

In this paper, the copper composite wires of 75 ?m in diameter with a sputtered layer of Ni80Fe20 permalloy were prepared, with a DC current applied to the basal Cu terminals during the fabrication process. The influence of the DC current on the magnetic configuration and Magneto-Impedance (MI) effect was studied. The results indicate that both the current amplitude and actuation duration have significant effect on the magnetic properties of the Ni80Fe20 layer. With appropriate current applied, the induced magnetic field leads to a circumferential magnetic domain structure and reduces significantly the equivalent anisotropy field of Ni80Fe20 layer. Then, the GMI ratio of the composite wires was significantly increased. A maximum GMI of 194.8% can be reached when the current was fixed at 100 mA and the Ni80Fe20 thickness is 780 nm. If the Ni80Fe20 thickness is above 780 nm, the coercivity of the coating layer increases while the GMI ratio of the composite wire reduces, since the magnetic anisotropy of the Ni80Fe20 layer varies from circumferential to longitudinal. The results were explained combining the thermal and magnetic effects of current.

Chen, Delu; Li, Xin; Ji, Xiaofeng; Zhao, Qiang; Ruan, Jianzhong; Zhao, Zhenjie

2014-06-01

59

Fly-by-Wire Systems Enable Safer, More Efficient Flight  

NASA Technical Reports Server (NTRS)

Using the ultra-reliable Apollo Guidance Computer that enabled the Apollo Moon missions, Dryden Flight Research Center engineers, in partnership with industry leaders such as Cambridge, Massachusetts-based Draper Laboratory, demonstrated that digital computers could be used to fly aircraft. Digital fly-by-wire systems have since been incorporated into large airliners, military jets, revolutionary new aircraft, and even cars and submarines.

2012-01-01

60

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

61

An Integrated Control System for Aircraft DC Generators  

Microsoft Academic Search

This paper describes an electric system for d-c generators used on aircraft that allows physical integration of all control elements normally associated with the control of the generator. The proposed system differs from the present system used by the Army and Navy primarily in that integration has been accomplished in addition to offering automatic control of the generator without a

A. T. McClinton

1947-01-01

62

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

63

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

64

Electrohydrodynamic force produced by a wire-to-cylinder dc corona discharge in air at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Wire-to-cylinder corona discharges are studied to better understand the electrohydrodynamic (EHD) phenomena that govern the performances of electric propulsion systems. First, theory associated with EHD thrusters is presented in order to be compared with experimental results. Secondly, direct thrust measurements are carried out to optimize the electrical and geometrical parameters of such devices. The main results are as follows: (1) the discharge current I is proportional to the square root of the grounded electrode diameter and to 1/d2 where d is the electrode gap; (2) for d ? 20 mm, the mobility of negative ions is higher than that of positive ions while the mobility of both ions is equal for higher gaps; (3) therefore, for gap ?30 mm, positive and negative coronas results in the same current-to-thrust conversion; (4) the current-to-thrust conversion is equal to 33 N A-1 per centimetre of gap, and it is proportional to the gap; (5) the thruster effectiveness ? increases with \\sqrt d , decreases with the square root of thrust and reaches about 15 N kW-1 for d = 40 mm (6) the force computed from experimental velocity profiles is overestimated compared with the values measured with a balance, showing that this method cannot be used for thrust determination.

Moreau, Eric; Benard, Nicolas; Lan-Sun-Luk, Jean-Daniel; Chabriat, Jean-Pierre

2013-11-01

65

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

66

Reliability Research for Steer-by-Wire System of Electric Vehicle  

Microsoft Academic Search

Steer-by-wire system of electric vehicle must meet the real-time and reliability requirements. An approach in how to estimate the reliability of steer-by-wire system considering the delay caused by network transmission errors is proposed. In the paper, a distributed architecture of steer-by-wire system is researched to analyze the delay time of the system, and design the TDMA slots of FlexRay bus.

Lijun Zhang; Lifang Wang; Chenglin Liao

2009-01-01

67

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

68

dc side active power filters for aircraft electric power systems  

Microsoft Academic Search

A dc side active filter for a 400 Hz aircraft electric power system is proposed. The filter provides continuous adjustable reactive power, has fast response and high efficiency, and does not necessitate excess capacitive kVA required to supply highly unbalanced or nonlinear loads.

P. Enjeti; S. Kim

1992-01-01

69

Active disturbance rejection control in steering by wire haptic systems.  

PubMed

This paper introduces a steering by wired haptic system based on disturbance rejection control techniques. High gain Generalized Proportional Integral (GPI) observers are considered for the estimation of tire and steering wheel dynamic disturbances. These disturbances are on line canceled to ensure tracking between the commanded steering wheel angle and the tire orientation angle. The estimated disturbances at the steering rack are feedback to the steering wheel to provide a haptic interface with the driver. The overall system behaves as a bilateral master-slave system. Very few sensors and minimum knowledge of the dynamic model are required. Experimental results are presented on a prototype platform that consists on: (1) half of the steering rack of a beetle VW vehicle, (2) a steering wheel. PMID:23978660

Rodriguez-Angeles, A; Garcia-Antonio, J A

2014-07-01

70

Mathematical simulation of DC arc furnace operation in electric power systems  

Microsoft Academic Search

Modern high-power DC electric arc furnaces (DC EAF) are considerable sources of power quality impacts in the electric supply systems. These impacts result from the feeding converters, but particularly also from the electric arc in the DC circuit. For an exact analysis of the DC EAF influence on the electric network, both the converter and the electric arc have to

D. Stade; H. Schau; I. Aprelkov; A. Novitskiy

1998-01-01

71

Design and development of a DC-DC converter for a fuel cell inverter system  

E-print Network

-acid batteries are provided on the high voltage DC bus to supply sudden load demands. Efficient and smooth control of the power drawn from the fuel cell and the high voltage battery is achieved by controlling the front end DC-DC converter in current mode....

Gopinath, Rajesh

2012-06-07

72

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

73

Output feedback trajectory stabilization of the uncertainty DC servomechanism system.  

PubMed

This work proposes a solution for the output feedback trajectory-tracking problem in the case of an uncertain DC servomechanism system. The system consists of a pendulum actuated by a DC motor and subject to a time-varying bounded disturbance. The control law consists of a Proportional Derivative controller and an uncertain estimator that allows compensating the effects of the unknown bounded perturbation. Because the motor velocity state is not available from measurements, a second-order sliding-mode observer permits the estimation of this variable in finite time. This last feature allows applying the Separation Principle. The convergence analysis is carried out by means of the Lyapunov method. Results obtained from numerical simulations and experiments in a laboratory prototype show the performance of the closed loop system. PMID:22884179

Aguilar-Ibaez, Carlos; Garrido-Moctezuma, Ruben; Davila, Jorge

2012-11-01

74

Research on 1Wire Bus Temperature Monitoring System  

Microsoft Academic Search

Based on 1-Wire bus technology, the 1-Wire bus temperature monitoring MicroLan was designed through using computer serial communication port, protocol transform chip DS2480 and 1-Wire bus digital temperature sensor DS18B20. The structure, character, ROM command, function command of DS18B20 and operating principle of DS2480B were analyzed. Consequently, the interface circuit between 1-Wrie bus and COM port is provided. At the

Wang Jingzhuo; Gong Chenglong

2007-01-01

75

Solid state circuit breakers enabling optimised protection of DC aircraft power systems  

Microsoft Academic Search

Greater utilisation of DC power distribution within aircraft systems is still largely prevented by the significant challenge of developing lightweight, effective DC protection systems. By considering circuit breaker, fault detection and power network design aspects, this paper proposes new performance criteria for optimised protection of DC aircraft power systems and discusses the resulting system level design and operability benefits which

Steven Fletcher; Patrick Norman; Stuart Galloway; Graeme Burt

2011-01-01

76

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

77

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

78

Fatigue analysis of the taut-wire mooring system applied for deep waters  

Microsoft Academic Search

Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of mooring lines in a rough sea environment especially in deep waters. In this paper, a comprehensive fatigue analysis is performed for a polyester taut-wire mooring system of an FPSO

Wei Huang; Hai-Xiao Liu; Gui-Min Shan; Cun Hu

2011-01-01

79

NASA/Ames Research Center DC-8 data system  

NASA Technical Reports Server (NTRS)

In-flight facility data acquisition, distribution, and recording on the NASA Ames Research Center (ARC) DC-8 are performed by the Data Acquisition and Distribution System (DADS). Navigational and environmental data collected by the DADS are converted to engineering units and distributed real-time to investigator stations once per second. Selected engineering units data are printed and displayed on closed circuit television monitors throughout flights. An in-flight graphical display of the DC-8 flight track (with barbs indicating wind direction and magnitude) has recently been added to the DADS capabilities. Logging of data run starts/stops and commentary from the mission director are also provided. All data are recorded to hard disk in-flight and archived to tape medium post-flight. Post-flight, hard copies of the track map and mission director's log are created by the DADS. The DADS is a distributed system consisting of a data subsystem, an Avionic Serial Data-to-VMEbus (ASD2VME) subsystem, and a host subsystem. Each subsystem has a dedicated central processing unit (CPU) and is capable of stand-alone operation. All three subsystems are housed in a single 20-slot VME chassis and communicate with each other over the VMEbus. The data and host subsystems are briefly discussed, and the DC-8 DADS internal configuration and system block diagram are presented.

Cherniss, S. C.; Scofield, C. P.

1991-01-01

80

Genetic Control of Wiring Specificity in the Fly Olfactory System  

PubMed Central

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

81

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

82

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

83

78 FR 1 - Prevailing Rate Systems; Abolishment of the Washington, DC, Special Wage Schedule for Printing...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Abolishment of the Washington, DC, Special Wage Schedule for Printing Positions AGENCY: U.S. Office of Personnel Management...Washington, DC, Federal Wage System special wage schedule for printing and lithographic positions. The final rule incorrectly...

2013-01-02

84

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 the load on the receiver coil is to use a step-down converter in place of a step- up. In such a system systems using step-up (a) and step- down (b) DC/DC power converters. In this paper, we present a general

Phang, Khoman

85

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

86

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

87

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

88

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

89

Title LIFE-TIME POWER EFFICIENCY IMPROVEMENT OF DISTRIBUTED PHOTO- VOLTAIC DC-DC INVERTERS IN SOLAR PANEL SYSTEMS  

E-print Network

Photo-voltaic solar panels provide a very attractive solution for future clean energy provision on site. Today's panels provide a relatively high efficiency under optimal conditions and when just fabricated. However, when external temperature, radiation angle, and radiation concentration conditions are varying, also the power efficiency fluctuates quite heavily. This is partly also true for the DC-DC inverter subsystem, especially when seen in the interaction with the solar modules. The range of these effects heavily depends on the context in which these panels are used and on the type of circuits and technology used. In this thesis, we want to model the DC-DC inverter circuits, especially for a distributed case where they are partly integrated into the solar modules. Also the control of these inverters will be investigated. We want to explore the effects of the different parameters and identify which of those effects can be effectively mitigated or counter acted. This will contribute heavily to the efficiency over the entire life time of the future solar system, with minimal hardware cost increase. That will result in a large practical impact of the work in this thesis. Keywords: photovoltaic DC-DC inverter, power-efficiency analysis, efficiency improving control, comparison of techniques

Contact Person Reinhart; Promotor Prof; Francky Catthoor; Prof Johan Driesen (imec-leuven; K. U. Leuven; Prof Francky Catthoor; Prof Johan Driesen

90

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

91

A control system for dc arc furnaces for power quality improvements  

Microsoft Academic Search

The dc arc furnaces are highly disturbing loads for transmission and distribution networks. The present paper proposes and implements an acdc converter control system for power quality improvements taking into account both flicker levels and harmonics at the point of common coupling. Different set of parameters for the proportionalintegral controller are investigated for optimizing the dc arc furnace power quality

G. C. Lazaroiu; D. Zaninelli

2010-01-01

92

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

93

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

94

Development and Analysis of a Wire-Based Robot With Twin Direct-Drive Motor System  

NASA Astrophysics Data System (ADS)

In this paper, a sensorless wire rope tension control is introduced and analyzed to implement a wire-based robot with twin direct-drive motor system. Two of the same direct-drive motors are required and connected by wire rope mechanism. In the controller design, dual disturbance observers with respect to two control modes, namely the common mode and the differential mode are designed and applied for control of motion and wire rope tension. The wire rope tension in the common mode is controlled in order to regulate the mechanical bandwidth of the system. From the identification results, the high-tension of wire rope system is obtained a high mechanical bandwidth in the robot systems. The disturbance observer-based eliminates the need for the tension sensors, and may also be used to achieve the precise velocity and position control with the vibration-free performance in the differential mode. The effectiveness of the proposed method is verified by experimental results. It is shown that the high frequency responses are obtained by using high-tension of wire rope. The control performance may improve during the robot operation and, therefore, it is useful to compensate for the vibration effect.

Mitsantisuk, Chowarit; Ohishi, Kiyoshi; Urushihara, Shiro; Katsura, Seiichiro

95

Prospective, randomized, single blinded pilot study of a new FlatWire based sternal closure system  

PubMed Central

Background Unstable steel wire cerclage following open heart surgery may result in increased pain, sternal cut-through, non-union, or dehiscence. These complications lead to longer hospital stays, increased cost, higher morbidity, and patient dissatisfaction. The Figure 8 FlatWire Sternal Closure System is a new construct which is a simple, intuitive, and inexpensive alternative for primary sternal repair following open heart surgery. Prior bench-top testing of FlatWire has demonstrated superior strength and stiffness compared to traditional steel wire. We present our initial experience in a prospective, randomized, single blinded pilot study utilizing this FDA approved system. Methods Sixty-three patients undergoing elective complete sternotomies at a single institution were randomly assigned to receive either the Figure 8 FlatWire or standard steel wire cerclage. All surgeries were performed by a single board certified cardiothoracic surgeon. Data collected included: Age, BMI, pump time, off pump to surgical stop time, length of hospital stay after surgery, cost from time of surgery to discharge, and pain on a visual analog pain scale on the day of discharge, day 30, and day 60. Results The groups were well matched. Patients receiving the Figure 8 FlatWire (33) had a reduction in length of stay compared to patients receiving steel wire circlage (30), but it was not statistically significant (6.8 vs. 7.8days respectively, p?Wire reported significantly decreased pain at day of discharge (3.07 vs. 4.92 points on pain scale, p?Wire vs. steel wires (55.7 vs. 71.6minutes, p?=?0.00025). Mean cost from surgery until discharge was $87,820.98 in the FlatWire group vs. $91,930.29 in the steel wire group (p?Wire provides excellent stability, which resulted in significantly diminished postoperative pain at discharge. Although not significant there was a trend toward decreased length of stay, and reduced cost. Further clinical research is warranted to expand upon these initial trends and validate long term outcomes. PMID:24889138

2014-01-01

96

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

97

A DB\\/DC platform for real-time operating systems based on CTRON specifications  

Microsoft Academic Search

A database and data communication (DB\\/DC) platform was developed for real-time operating systems based on CTRON specifications in order to create high performance online transaction processing systems such as network operation control systems. The DB\\/DC platform is designed to be portable and to achieve high performance. The authors describe the software architecture of the DB\\/DC platform for real-time operating systems

Takuo Nishihara; Junichi Kikuchi; Tomoji Takehisa

1992-01-01

98

Identification of twin direct-drive motor system with consideration of wire rope tension  

Microsoft Academic Search

An adaptable stiffness of mechanical using wire rope tension control, called as a twin direct-drive motor system, has unique advantages in human-robot interaction system, when compared with conventional industrial robot. Since the wire rope is low friction and lightweight device, it is possible to achieve high-efficiency, high degree of reliability, and safety. In this paper, modeling and closed-loop identification of

Chowarit Mitsantisuk; Kiyoshi Ohishi; S. Urushihara; S. Katsura

2009-01-01

99

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

100

NASA requirements and applications environments for electrical power wiring  

NASA Technical Reports Server (NTRS)

While a large data base for electrical arc track-resistant wire insulation exists for aircraft electrical power systems, comparable spacecraft-pertinent data are in limited supply. Existing insulation systems have been found to arc-track at potentials as low as 28 V dc. An account is presently given of the electrical, thermal, mechanical, and operational requirements for specification and testing of candidate wiring systems for spacecraft applications.

Stavnes, Mark W.; Hammond, Ahmad N.

1992-01-01

101

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

102

DC graphite arc furnace and diagnostic system for soils  

SciTech Connect

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. The national laboratory provides the problem and funding while transferring technology to industry and the university. The goal of the program is to apply EPI`s Arc Furnace to the processing of Subsurface Disposal Area (SDA) waste from Idaho National Engineering Laboratory (INEL). This is being facilitated through the Department of Energy`s Buried Waste Integrated Demonstration (BWID) program. A second objective is to apply the diagnostics capability of MIT`s Plasma Fusion Center to the understanding of the high temperature processes taking place in the furnace. This diagnostics technology has promise for being applicable in other thermal treatment processes. The program has two parts, a test series in an engineering-scale DC arc furnace which was conducted in an EPI furnace installed at the Plasma Fusion Center and a pilot-scale unit which is under construction at MIT. This pilot-scale furnace will be capable of operating in a continuous feed and continuous tap mode. Included in this work is the development and implementation of diagnostics to evaluate high temperature processes such as DC arc technology. Results of the testing during the engineering test phase of the program are discussed. These results include a discussion of the superior product stability to leaching of the reduced glass products. 9 refs., 4 figs., 3 tabs.

Wittle, J.K.; Titus, C.H.; Hamilton, R.A. [Electro-Pyrolysis, Inc., Wayne, PA (United States)] [and others

1994-12-31

103

Transient analysis of an HTS DC power cable with an HVDC system  

NASA Astrophysics Data System (ADS)

The operational characteristics of a superconducting DC power cable connected to a highvoltage direct current (HVDC) system are mainly concerned with the HVDC control and protection system. To confirm how the cable operates with the HVDC system, verifications using simulation tools are needed. This paper presents a transient analysis of a high temperature superconducting (HTS) DC power cable in connection with an HVDC system. The study was conducted via the simulation of the HVDC system and a developed model of the HTS DC power cable using a real time digital simulator (RTDS). The simulation was performed with some cases of short circuits that may have caused system damage. The simulation results show that during the faults, the quench did not happen with the HTS DC power cable because the HVDC controller reduced some degree of the fault current. These results could provide useful data for the protection design of a practical HVDC and HTS DC power cable system.

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun; Yang, Byeongmo

2013-11-01

104

Study on nondestructive detection system based on x-ray for wire ropes conveyer belt  

NASA Astrophysics Data System (ADS)

A nondestructive detection system based on X-ray for wire ropes conveyer belt is designed by X-ray detection technology. In this paper X-ray detection principle is analyzed, a design scheme of the system is presented; image processing of conveyer belt is researched and image processing algorithms are given; X-ray acquisition receiving board is designed with the use of FPGA and DSP; the software of the system is programmed by C#.NET on WINXP/WIN2000 platform. The experiment indicates the system can implement remote real-time detection of wire ropes conveyer belt images, find faults and give an alarm in time. The system is direct perceived, strong real-time and high accurate. It can be used for fault detection of wire ropes conveyer belts in mines, ports, terminals and other fields.

Miao, Changyun; Shi, Boya; Wan, Peng; Li, Jie

2008-03-01

105

Modelling of a DC arc furnace for optimal integration with the supply system  

SciTech Connect

DC arc furnaces have recently gained increasing favor with steel makers all over the world. DC arc furnaces have advantages over their conventional AC counterparts because of their greater supply-friendly nature. Although DC arc furnaces still generate flicker, the stochastic component in their harmonics are reduced and their demands on the supply network are much more compatible with the supply than that of AC arc furnaces. In spite of the relative advantages, however, the input characteristics of DC furnaces still need to be quantified in order to achieve optimal integration with the supply system. System measurements on a 25 MVA DC arc furnace with its filters are correlated with results obtained by numerical integration, and with that obtained through a frequency-domain analytical model that employs harmonic superposition. The behavior of induction motors is also investigated in this model, when they are subjected to the voltage distortion produced by a DC furnace.

Bekker, J.; Swart, P.H.; Landy, C.F.; Marshall, D.A.

1995-12-31

106

Smart power flow control in DC distribution systems involving sustainable energy sources  

Microsoft Academic Search

In this paper, a detailed description of a proposed technique for power flow control in DC distribution systems has been presented. The DC system under study is assumed mainly dependent on renewable energy sources. The proposed topology utilizes a controlled series current compensator (CSCC) technique for connection and power flow control among buses. The proposed topology allows full power flow

A. Mohamed; O. Mohammed

2010-01-01

107

Strata reinforcement with bolting and wire-rope systems - a comparative study  

SciTech Connect

A strata reinforcement system which has been used on an experimental basis in some 60 Indian coal mines over the past 6 years is described. It consists of a system of 'rope stitching' in which wire rope is stretched across the roof of the roadway and the ends are grouted into 1.8 m drill holes. For spans exceedng 3.6 m, grouted bolts with eye hooks are used for additional reinforcement at mid-span. This paper presents the results of a model study to evaluate the relative reinforcement actions of wire-rope and bolting systems.

Raju, N.M.; Ghose, A.K.

1982-04-01

108

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

109

Biological wires, communication systems, and implications for disease.  

PubMed

Microtubules, actin, and collagen are macromolecular structures that compose a large percentage of the proteins in the human body, helping form and maintain both intracellular and extracellular structure. They are biological wires and are structurally connected through various other proteins. Microtubules (MTs) have been theorized to be involved in classical and quantum information processing, and evidence continues to suggest possible semiconduction through MTs. The previous Dendritic Cytoskeleton Information Processing Model has hypothesized how MTs and actin form a communication network in neurons. Here, we review information transfer possibilities involving MTs, actin, and collagen, and the evidence of an organism-wide high-speed communication network that may regulate morphogenesis and cellular proliferation. The direct and indirect evidence in support of this hypothesis, and implications for chronic diseases such as cancer and neurodegenerative diseases are discussed. PMID:25448891

Friesen, Douglas E; Craddock, Travis J A; Kalra, Aarat P; Tuszynski, Jack A

2015-01-01

110

Measurements of the dc Josephson current in proximity systems  

SciTech Connect

Junctions modeled as [ital S]-[ital N]/[ital I]/[ital S] and [ital S]-[ital N]/[ital I]/[ital N]-[ital S] proximity systems (where [ital S], [ital I], and [ital N] indicate a superconductor, an insulator, and a normal metal, respectively) are widely discussed in literature from both the experimental and theoretical point of view. In the present paper experimental aspects concerning Nb/Nb junctions including a proximity bilayer are considered. Nb-[ital M]/[ital I]/Nb and [ital M]-Nb/[ital I]/Nb structures (where [ital M] is a normal metal, a semimetal, or a superconductor) are investigated by using a semimetal (bismuth) and a superconductor (aluminum) as the [ital M] layer. In particular, how the deposition of a back layer influences the behavior of Nb/[ital I]/Nb high-quality junctions is discussed, focusing the interest on measurements of the temperature dependence of the maximum dc Josephson current. Experimental data are discussed in the framework of Kresin's theoretical calculations based on the thermodynamic Green's function method.

Camerlingo, C.; Monaco, R.; Ruggiero, B.; Russo, M. (Istituto di Cibernetica del Consiglio Nazionale delle Ricerche, I-80072 Arco Felice (Napoli) (Italy)); Testa, G. (Istituto Nazionale di Fisica Nucleare, I-80125 Napoli (Italy))

1995-03-01

111

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.

112

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

113

Characteristics of a large system of pad readout wire proportional chambers for the HPC calorimeter  

SciTech Connect

A large system of wire proportional chambers is being constructed for the readout of the High-Density Projection Chamber (HPC) of the DELPHI experiment at the Large Electron-Positron storage ring. The system consists of 144 chambers, each 0.3 m/sup 2/ wide and read out via cathode pads, located at the end of the HPC drift volume.

Camporesi, T.; Cavallo, F.R.; Giordano, V.; Laurenti, G.; Molinari, G.; Navarria, F.L.; Privitera, P.; Rovelli, T.; Valenti, G.; Zucchini, A.

1989-02-01

114

PATEGE: An Automatic DC Parametric Test Generation System for Series Gated ECL Circuits  

Microsoft Academic Search

For ECL circuits, DC parametric tests such as input current (IIL, IIH), reference voltage (VBB), and power supply current (ICC) tests are executed as well as functional tests. This paper describes an automatic DC parametric test generation system PATEGE for the series gated ECL circuits. PATEGE can automatically generate the test patterns and calculate the expected values for IIL, IIH,

Takuji OGIHARA; S. Saruyama; S. Murai

1985-01-01

115

PATEGE: an automatic DC parametric test generation system for series gated ECL circuits  

Microsoft Academic Search

For ECL circuits. DC parametric tests such as input current (IIL IIH), reference voltage (VBB), and power supply current (ICC) tests are executed as well as functional tests.This paper describes: an automatic DC parametric test generation system PATEGE for the series gated ECL circuits. PATEGE can automatically generate the test patterns and calculate the expected values for IIL, IIH, VBB

Takuji Ogihara; Shuichi Saruyama; Shinichi Murai

1985-01-01

116

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

117

The Decentralized Power DC Unit in the Energy System (Geode) for Telecommunications Equipments  

Microsoft Academic Search

After a general presentation of a new kind of supply systems for telecommunication exchange developped from the A.C. source to DC outputs ; we give an overview of one of its most important subset: the decentralized DC rack ; it will be another opportunity to emphasize concepts like : - short battery autonomy, - use of the redundancy on the

J. P. Leblanc; D. Marquet; G. Gatine

1987-01-01

118

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

119

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

120

Compensation of Voltage Drop using Substation Support Equipment for DC Feeding System  

NASA Astrophysics Data System (ADS)

In DC electric railways, power is supplied to trains from DC substations. The voltage gets declined at a pantograph on the way due to the voltage drop caused by impedance, in particular the resistance of feeding wires. In case the load of rolling stock gets heavy, the significant voltage drop may hinder the train from continuous operations. Two methods have been conventionally used to deter the voltage drop. One ways is to decrease resistance of the circuit by the application of feeder with bigger diameter. Another is to compensate the voltage drop by the installation of the new substation between two existing substations. These two methods are effective; however, there are problems of term and cost for installation. Based on these issues we have recently developed the new method which we call "substation support equipment". In this paper we report the basic concept and overview for the substation support equipment together with results of performance test on site and artificial fault test.

Kawahara, Keiji; Hase, Shin-Ichi; Morimoto, Hiroaki; Umeda, Shigeki; Takahashi, Norio

121

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

122

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

123

75 FR 36298 - Airworthiness Directives; McDonnell Douglas Corporation Model DC-8-31, DC-8-32, DC-8-33, DC-8-41...  

Federal Register 2010, 2011, 2012, 2013, 2014

...series airplanes; Model DC-8-60F series airplanes; Model DC-8-70 series airplanes; and Model DC-8-70F series airplanes. That AD requires revising...bundles as power wires. If a short circuit between a float switch wire and...

2010-06-25

124

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

125

A system for the measurement of wire-rope defect positions  

Microsoft Academic Search

Electromagnetic tests are nowadays widely employed to early detect defects of metallic wire ropes. Commercial instruments for electromagnetic tests are able to highlight small defects but provide only a rough estimation of their positions. An analysis of the uncertainty contributions that affect the defect position measurements is described in this paper and an improved measurement system is also presented. The

A. Vallan

2004-01-01

126

Turbulence Measurements by the DC-8 Meteorological Measurement System  

NASA Technical Reports Server (NTRS)

The instrumentation of a new MMS on the DC-8 aircraft is briefly described. Methods to compute and evaluate the turbulent dissipation rate epsilon, based on theory and MMS data, are discussed. Examples of turbulence measurements during encounters of a wake vortex, wave clouds, persistent contrails, mountain are gravity waves are illustrated.

Chan, K. R.; Dean-Day, J.; Bowen, S. W.; Bui, T. P.; Chan, K. Roland (Technical Monitor)

1997-01-01

127

Power Sharing Control between Load-Side Inverters in DC Microgrid for Super High Quality Electric Power Distribution System  

NASA Astrophysics Data System (ADS)

DC microgrid is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc distribution line and converted to required ac or dc voltage by converters placed near loads. Load-side single phase inverters are connected through transformers in order to share active and reactive power. In this paper, a power sharing control scheme was proposed, and the power sharing characteristics were demonstrated by experimental results.

Kakigano, Hiroaki; Nada, Kaho; Miura, Yushi; Ise, Toshifumi; Uchida, Ryohei

128

Design considerations of a cable wiring system for a new medical center to support a future medical imaging system  

NASA Astrophysics Data System (ADS)

Our Medical Center is faced with the problem to design a cable wiring system today, install it by the middle 1990''s, and allow for upgrades and enhancements for the next ten to fifteen years. The cable plant must be able to support functions and activities which are poorly defined today, but will include the hospital information system (HIS), a future picture archiving and communication system (PACS), and possibly an electronic patient chart with integrated image data. The cable plant must also connect to a future campus wide Medical Network of the Indiana University Medical center with the first component being a positron emission tomography system (PET) located approximately one mile away. To meet these goals the proposed cable plant will be a structured wire cabling system following existing and proposed standards for building wiring architectures including the Electronics Industries Association (EIA) and the Telecommunications Industries Association (TIA) 568 Commercial Building Wiring Standard and the proposed Federal Telecommunication Standard 1090. The structured wiring system approached has been evaluated with emphasis on the present and future network topologies that can be implemented, the type and size of fiber optic cable to install, and the need to install fiber optic cable to individual workstations.

Witt, Robert M.; Emrich, Jack

1992-07-01

129

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

130

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

131

Effect of dc electric field on resonant acoustic phonon scattering in two-dimensional electron systems  

NASA Astrophysics Data System (ADS)

We study [1] the effect of dc electric field on transport properties of two-dimensional electron systems in which resonant acoustic phonon scattering dominates linear response resistivity. We observe that dc electric field strongly modifies phonon resonances, transforming resistance maxima into minima and back into maxima. Further, phonon resonances are enhanced dramatically in the non-linear dc response and can be detected even at low temperatures. Most of our observations can be explained by dc-induced (de)tuning of the acoustic phonon resonances and intra-Landau level impurity scattering. We also observe a dc-induced zero-differential resistance state and a resistance maximum which occurs when the electron drift velocity approaches the speed of sound. [1] W. Zhang, M.A. Zudov, L.N. Pfeiffer, and K.W. West, arXiv:0711.1547v1, Phys. Rev. Lett. (accepted for publication).

Zhang, Wenhao; Zudov, Michael; Pfeiffer, Loren; West, Ken

2008-03-01

132

Three-phase Four-wire Autonomous Wind Energy Conversion System Using Permanent Magnet Synchronous Generator  

Microsoft Academic Search

This article deals with an autonomous wind energy conversion system employing a permanent magnet synchronous generator feeding three-phase four-wire local loads in stand-alone mode without using a mechanical position sensor. The proposed autonomous wind energy conversion system utilizes two back-to-back connected pulse width modulated insulated gate bipolar transistors based voltage source converters with a battery energy storage system at their

Puneet K. Goel; Bhim Singh; S. S. Murthy; Shailendra K. Tiwari

2010-01-01

133

Evolution of the Design of a Second Generation FireWire Based Data Acquisition System.  

PubMed

Our laboratory has previously reported on the basic design concepts of an updated FireWire based data acquisition system for depth-of-interaction detector systems designed at the University of Washington. The new version of our data acquisition system leverages the capabilities of modern field programmable gate arrays (FPGA) and puts almost all functions into the FPGA, including the FireWire elements, the embedded processor, and pulse timing and integration. The design is centered around an acquisition node board (ANB) that includes 64 serial ADC channels, one high speed parallel ADC, FireWire 1394b support, the FPGA, a serial command bus and signal lines to support a rough coincidence window implementation to reject singles events from being sent on the FireWire bus. Adapter boards convert detector signals into differential paired signals to connect to the ANB. In this paper we discuss many of the design details, including steps taken to minimize the number of layers in the printed circuit board and to avoid skewing of parallel signals and unwanted bandwidth limitations. PMID:22228135

Lewellen, T K; Miyaoka, R S; Macdonald, L R; Haselman, M; Dewitt, D; Hauck, S

2010-10-30

134

Evolution of the Design of a Second Generation FireWire Based Data Acquisition System  

PubMed Central

Our laboratory has previously reported on the basic design concepts of an updated FireWire based data acquisition system for depth-of-interaction detector systems designed at the University of Washington. The new version of our data acquisition system leverages the capabilities of modern field programmable gate arrays (FPGA) and puts almost all functions into the FPGA, including the FireWire elements, the embedded processor, and pulse timing and integration. The design is centered around an acquisition node board (ANB) that includes 64 serial ADC channels, one high speed parallel ADC, FireWire 1394b support, the FPGA, a serial command bus and signal lines to support a rough coincidence window implementation to reject singles events from being sent on the FireWire bus. Adapter boards convert detector signals into differential paired signals to connect to the ANB. In this paper we discuss many of the design details, including steps taken to minimize the number of layers in the printed circuit board and to avoid skewing of parallel signals and unwanted bandwidth limitations. PMID:22228135

Lewellen, T.K.; Miyaoka, R.S.; MacDonald, L.R.; Haselman, M.; DeWitt, D.; Hauck, S.

2011-01-01

135

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

136

77 FR 41247 - Prevailing Rate Systems; Abolishment of the Washington, DC, Special Wage Schedule for Printing...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Washington, DC, Special Wage Schedule for Printing Positions AGENCY: U.S. Office of Personnel...Wage System (FWS) special wage schedule for printing and lithographic positions. Printing and lithographic employees in the...

2012-07-13

137

77 FR 74347 - Prevailing Rate Systems; Abolishment of the Washington, DC, Special Wage Schedule for Printing...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Washington, DC, Special Wage Schedule for Printing Positions AGENCY: U.S. Office of Personnel...Wage System (FWS) special wage schedule for printing and lithographic positions. Printing and lithographic employees in the...

2012-12-14

138

Optimum controller design for a multilevel AC-DC converter system  

Microsoft Academic Search

This paper focuses on the controller design based on symmetrical optimum and extended symmetrical optimum methods for a single-phase AC\\/DC converter system employing AC\\/AC direct converter and inverter with a medium frequency isolating transformer. Design criteria for the control system involve DC voltage control, reactive current control and AC current tracking. Simulation studies verify the designed controller performance for multi-level

Oguz Aydin; Alper Akdag; Philippe Stefanutti; Nicolas Hugo

2005-01-01

139

A multilevel voltage-source converter system with balanced DC voltages  

Microsoft Academic Search

In this paper, a multilevel voltage-source converter system is proposed for high-voltage, high-power applications such as back-to-back interconnection of power systems, large induction motor drives, and electrical traction drives. Multilevel voltage-source converters have a voltage unbalance problem in the DC capacitors. The problem may be solved by use of additional voltage regulators or separate DC sources. However, these solutions are

Fang Zheng Peng; Jih-Sheng Lai; John McKeever; James Vancoevering

1995-01-01

140

Department of Energy`s Wire Development Workshop - Superconductivity program for electric systems  

SciTech Connect

The 1996 High-Temperature Superconducting Wire Development Workshop was held on January 31--February 1 at the Crown Plaza Tampa Westshore in Tampa, Florida. The meeting was hosted by Tampa Electric Company and sponsored by the Department of Energy`s Superconductivity Program for Electric Systems. The meeting focused on recent high-temperature superconducting wire development activities in the Department of Energy`s Superconductivity Systems program. Tampa Electric`s Greg Ramon began the meeting by giving a perspective on the changes now occurring in the utility sector. Major program wire development accomplishments during the past year were then highlighted, particularly the world record achievements at Los Alamos and Oak Ridge National Laboratories. The meeting then focussed on three priority technical issues: thallium conductors; AC losses in HTS conductors; and coated conductors on textured substrates. Following in-depth presentations, working groups were formed in each technology area to discuss and critique 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.

NONE

1996-06-01

141

DC power system having battery voltage equalizer circuit  

SciTech Connect

An equalizer circuit is disclosed for permitting two series 12 volt batteries to supply both 24 volts and 12 volts and which maintains the batteries charged to equal voltages. The equalizer circuit is a regulated DC to DC converter with its output connected across the 12 volt battery which is connected to 12 volt loads and its input connected across either the other battery or the 24 volts of the input series pair of batteries. The reference voltage for the regulator is derived from a voltage dividing circuit which is connected across the 24 volt terminals of the two batteries. The voltage dividing circuit provides a reference voltage which is equal to half the voltage across the sum of the voltages of the two batteries.

Sullivan, J.D.

1984-10-23

142

Point of collapse methods applied to AC\\/DC power systems  

Microsoft Academic Search

The authors describe an extension of the point of collapse method developed for studies of AC systems to the determination of saddle-node bifurcations in power systems including high voltage direct current (HVDC) transmission. Bus voltage profiles are illustrated for an AC\\/DC test system. They significantly differ from the profiles of pure AC systems for typical system models. In particular, voltage

C. A. Canizares; Fernando L. Alvarado; Christopher L. DeMarco; Ian Dobson; Willis F. Long

1992-01-01

143

Power-by-wire aircraft secondary power systems  

Microsoft Academic Search

This paper describes the secondary power sources available on a large transport aircraft that supply power for the aircraft operating and payload systems. The benefits expected from integrating all of the engine-based hydraulic and pneumatic power sources into the electrical system are identified in qualitative terms. The estimated capacity of an all-electric secondary power system for a tri-jet and a

L. J. Feiner

1993-01-01

144

Detection of birdcaging in steel wire rope of a hoisting winch system by analysis of load torque and stator current  

Microsoft Academic Search

The aim of this paper is to analyze theoretically and experimentally the stator current of a three phase induction machine and load torque signals in a hoisting winch system, in order to show how they are influenced by the wire rope faulty condition. When the wire rope is subjected to axial and torsional loads, the outer strands can separate from

H. Henao; S. M. J. Rastegar Fatemi; S. Sieg-Zieba; G. A. Capolino

2009-01-01

145

A Configuration and Control Method of DC Loop Type Distribution System Including Distributed Generators  

NASA Astrophysics Data System (ADS)

In the large-scale factories like ironworks, many power electronic inverter loads exist, and these inverter loads are connected into ac systems by using rectifiers. On the other hand, DGs (Distributed Generators) such as photovoltaic generators and fuel cells, or ESSs (Energy Storage Systems) such as secondary batteries and SMESs (Superconducting Magnetic Energy Strages), which are dc power sources will be introduced to distribution systems more and more. These are connected into ac systems by using inverters. Therefore, it is expected that some countermeasures to achieve a dc distribution system which can reduce power losses due to rectifiers and inverters, should be developed. In this paper, a dc loop type distribution system is proposed as one of the new dc distribution system configurations. The calculation results of power losses for the dc loop type distribution system are compared with those for an ac distribution system. Moreover, this paper shows configurations and simulation results of the inverter, bi-directional rectifier and PFC (Power Factor Corrector) used in this system.

Saisho, Masaki; Ise, Toshifumi; Tsuji, Kiichiro

146

77 FR 58424 - Drucker, Inc., DynaMotive Energy Systems Corp., and Gate to Wire Solutions, Inc., Order of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...File No. 500-1] Drucker, Inc., DynaMotive Energy Systems Corp., and Gate to Wire Solutions, Inc., Order...information concerning the securities of DynaMotive Energy Systems Corp. because it has not filed any periodic...

2012-09-20

147

A bidirectional DC-DC converter for fuel cell electric vehicle driving system  

Microsoft Academic Search

This paper presents a power converter for a fuel cell electric vehicle driving system. A new bidirectional, isolated topology is proposed in consideration of the differing fuel cell characteristics from traditional chemical-power battery and safety requirements. The studied converter has the advantages of high efficiency, simple circuit, and low cost. The detailed design and operating principles are analyzed and described.

Huang-Jen Chiu; Li-Wei Lin

2006-01-01

148

Real-time system identification for load monitoring and transient handling of Dc-Dc supplies  

Microsoft Academic Search

Switching mode power supply (SMPS) behavior depends entirely upon known component values and often unknown load impedances. Load change produces voltage over- and undershoots and a design-point shift. In most cases, the controller is blind to these shifts. However, load knowledge is an essential design parameter and should precede optimal and adaptive control techniques. System identification algorithms implemented on digital

Grant E. Pitel; Philip T. Krein

2008-01-01

149

Through-space conjugated molecular wire comprising three ?-electron systems.  

PubMed

A [2.2]paracyclophane-based through-space conjugated oligomer comprising three ?-electron systems was designed and synthesized. The arrangement of three ?-conjugated systems in an appropriate order according to the energy band gap resulted in efficient unidirectional photoexcited energy transfer by the Frster mechanism. The energy transfer efficiency and rate constants were estimated to be >0.999 and >10(12) s(-1), respectively. The key point for the efficient energy transfer is the orientation of the transition dipole moments. The time-dependent density functional theory (TD-DFT) studies revealed the transition dipole moments of each stacked ?-electron system; each dipole moment was located on the long axis of each stacked ?-electron system. This alignment of the dipole moments is favorable for fluorescence resonance energy transfer (FRET). PMID:25056560

Morisaki, Yasuhiro; Kawakami, Naoya; Shibata, Shotaro; Chujo, Yoshiki

2014-10-01

150

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

151

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

152

System and Method for Determining Rate of Rotation Using Brushless DC Motor  

NASA Technical Reports Server (NTRS)

A system and method are provided for measuring rate of rotation. A brushless DC motor is rotated and produces a back electromagnetic force (emf) on each winding thereof. Each winding's back-emf is squared. The squared outputs associated with each winding are combined, with the square root being taken of such combination, to produce a DC output proportional only to the rate of rotation of the motor's shaft.

Howard, David E. (Inventor); Smith, Dennis A. (Inventor)

2000-01-01

153

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

154

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

155

Fatigue analysis of the taut-wire mooring system applied for deep waters  

NASA Astrophysics Data System (ADS)

Precisely predicting the fatigue life of taut-wire mooring systems has become an interesting and important problem for scientists and engineers since there are still difficulties in the inspection and maintenance of mooring lines in a rough sea environment especially in deep waters. In this paper, a comprehensive fatigue analysis is performed for a polyester taut-wire mooring system of an FPSO based on the time domain dynamic theory, rainflow cycle counting method and linear damage accumulation rule of Palmgren-Miner. Three influential factors in the fatigue analysis including the pre-tension, dynamic stiffness and T-N curve are investigated in detail. Two polyester T-N curves, one is from the DNV-OS-E301 and the other is from the API-RP-2SM, are adopted in the calculation. The fatigue analysis of the mooring system after one-line failure is also carried out. The calculation results indicate that the fatigue life is significantly affected by the T-N curve. The fatigue life decreases with increasing pre-tension, and is largely reduced if taking into account the dynamic stiffness caused by cyclic loading. The analysis also proves that one-line failure has remarkable effects on the fatigue lives of other mooring lines. The present parametric and comparative study is believed to be meaningful to further understanding of the taut-wire mooring system for deepwater applications.

Huang, Wei; Liu, Hai-Xiao; Shan, Gui-Min; Hu, Cun

2011-09-01

156

Avian Hatching Monitor and Control System Based on 1Wire Sensor Groups  

Microsoft Academic Search

System selects temperature sensor DS18B20 and humidity sensor HS1101 to compose sensor groups after analyzing avian hatching requirement, which realizes temperature and humidity automatic monitor and control through 1-wire bus technology. Sensor groups complete field hatching temperature\\/ humidity monitor and transmit analog signal into digital signal, single chip microprocessor (SCM) AT89C51 as core controller processes it, drives actuators to realize

Wen Xinling

2008-01-01

157

Computer simulation of a resonant dc link for advanced launch systems  

NASA Technical Reports Server (NTRS)

The performance of a resonant dc link based actuator power system being built for an advanced launch system application is evaluated for a typical launch scenario using two end-to-end system simulations, one using a digital computer and the other using a hybrid computer. Aspects of system performance from the switching of the power electronic devices to the vehicle aerodynamics are addressed. Using these simulations, it is shown that the resonance dc link actuator adequately stabilize the vehicle against a wind gust during a launch.

Sudhoff, S. D.; Wasynczuk, O.; Krause, P. C.; Kenny, B. H.

1993-01-01

158

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

159

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

160

A Gate-Array Implementation of a DC-Motor Control System  

Microsoft Academic Search

A digital chip has been designed for a permanent-magnet DC motor control system based on pulse-width modulation techniques. The control system is used for cordless drilling and screwdriver machines. The system is implemented on a new, low latch-up susceptibility CMOS gate array.

H. G. Kerkhoff; M. van Bentem; E. A. de Boer

1989-01-01

161

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

162

Wire Maze  

NSDL National Science Digital Library

Students gain a basic understanding of electrical circuits. They build wire circuits and pass paperclips through the mazes, trying not to touch the wires. Touching a wire with a paperclip causes the circuit to close, which activates an indicator.

K-12 Outreach Office,

163

30 CFR 75.803-2 - Ground check systems not employing pilot check wires; approval by the Secretary.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution 75.803-2 Ground check systems not employing pilot check wires; approval by the...

2010-07-01

164

30 CFR 77.803-2 - Ground check systems not employing pilot check wires; approval by the Secretary.  

Code of Federal Regulations, 2010 CFR

...HEALTH MANDATORY SAFETY STANDARDS, SURFACE COAL MINES AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Surface High-Voltage Distribution 77.803-2 Ground check systems not employing pilot check wires; approval by the...

2010-07-01

165

The influence of bracket design on frictional losses in the bracket/arch wire system.  

PubMed

In arch guided tooth movement, the essential role played by bracket configuration with respect to sliding friction has been recognized by the manufacturers, a fact which has had an increasing impact on the design and marketing of new bracket models in recent years. The aim of the present in-vitro study was to investigate the influence of different bracket designs on sliding mechanics. Five differently shaped stainless steel brackets (Discovery: Dentaurum, Damon SL: A-Company, Synergy: Rocky Mountain Orthodontics, Viazis bracket and Omni Arch appliance: GAC) were compared in the 0.022"-slot system. The Orthodontic Measurement and Simulation System (OMSS) was used to quantify the difference between applied force (NiTi coil spring, 1.0 N) and orthodontically effective force and to determine leveling losses occurring during the sliding process in arch guided tooth movement. Simulated canine retraction was performed using continuous arch wires with the dimensions 0.019" x 0.025" (Standard Steel, Unitek) and 0.020" x 0.020" (Ideal Gold, GAC). Comparison of the brackets revealed friction-induced losses ranging from 20 to 70%, with clear-cut advantages resulting from the newly developed bracket types. However, an increased tendency towards leveling losses in terms of distal rotation (maximum 15 degrees) or buccal root torque (maximum 20 degrees) was recorded, especially with those brackets giving the arch wire increased mobility due to their shaping or lack of ligature wire. PMID:10546416

Schumacher, H A; Bourauel, C; Drescher, D

1999-01-01

166

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

167

Flight experience with a fail-operational digital fly-by-wire control system  

NASA Technical Reports Server (NTRS)

The NASA Dryden Flight Research Center is flight testing a triply redundant digital fly-by-wire (DFBW) control system installed in an F-8 aircraft. The full-time, full-authority system performs three-axis flight control computations, including stability and command augmentation, autopilot functions, failure detection and isolation, and self-test functions. Advanced control law experiments include an active flap mode for ride smoothing and maneuver drag reduction. This paper discusses research being conducted on computer synchronization, fault detection, fault isolation, and recovery from transient faults. The F-8 DFBW system has demonstrated immunity from nuisance fault declarations while quickly identifying truly faulty components.

Brown, S. R.; Szalai, K. J.

1977-01-01

168

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

169

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

170

Solar energy system performance evaluation, Forest City Dillon, Washington, DC, January 1981 through December 1981  

Microsoft Academic Search

The Forest City Dillon solar energy system is the Fort Lincoln Senior Village apartment complex in Washngton, DC. The active solar energy system is designed to supply 59% of the hot water, and consists of 2592 square feet of flat plate collectors, 3200-gallon storage tank, and an auxiliary oil-fired boiler. Performance data are given for each month of 1981 for

Pakkala

1981-01-01

171

Grid connected DC distribution system for efficient integration of sustainable energy sources  

Microsoft Academic Search

In this paper, some of the aspects related to the design and implementation of grid connected DC microgrids are investigated. A prototype system has been designed and implemented to address these aspects. The described system is dependent mainly on sustainable energy sources. Hence, a special care has been given to dealing with these kinds of sources while designing different components

M. Elshaer; A. Mohamed; O. Mohammed

2011-01-01

172

A universal DC characterisation system for hard and soft magnetic materials  

Microsoft Academic Search

A fully automatic system has been designed for the accurate measurement of the DC magnetic properties of soft and hard ferromagnetic materials utilising discrete calibrated instruments in order to provide a traceable calibration route separate from the transfer of standard magnetic test samples. Custom written software is used to operate the system in one of three modes, constant dH\\/dt, variable

Philip Anderson

2008-01-01

173

Design and construction evaluation of a photovoltaic DC LED lighting system  

Microsoft Academic Search

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

Jyotsna Bhamidipati

2008-01-01

174

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

175

Parametric excitation of dc current in a single-dot shuttle system via spontaneous symmetry breaking  

NASA Astrophysics Data System (ADS)

We investigate theoretically the dynamics of a spatially symmetric shuttle system subjected to an ac gate voltage. We demonstrate that in such a system parametric excitation gives rise to mechanical vibrations when the frequency of the ac signal is close to the eigenfrequency of the mechanical subsystem. These mechanical oscillations result in a dc shuttle current in a certain direction due to spontaneous symmetry breaking. The direction of the current is determined by the phase shift between the ac gate voltage and the parametrically excited mechanical oscillations. The dependence of the shuttle current on the dc gate voltage is also analyzed.

Pea-Aza, Milton E.; Scorrano, Alessandro; Gorelik, Leonid Y.

2013-07-01

176

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

177

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

178

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

179

A novel multicell DC-AC converter for applications in renewable energy systems  

Microsoft Academic Search

This paper presents a novel DC-AC converter for applications in the area of distributed energy generation systems, e.g., solar power systems, fuel-cell power systems in combination with supercapacitor or battery energy storage. The proposed converter is realized using an isolated multicell topology where the total AC output of the system is formed by series connection of several full-bridge converter stages.

Hans Ertl; Johann W. Kolar; Franz C. Zach

2002-01-01

180

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

181

Preliminary system design study for a digital fly-by-wire flight control system for an F-8C aircraft  

NASA Technical Reports Server (NTRS)

The design of a fly-by-wire control system having a mission failure probability of less than one millionth failures per flight hour is examined. Emphasis was placed on developing actuator configurations that would improve the system performance, and consideration of the practical aspects of sensor/computer and computer/actuator interface implementation. Five basic configurations were defined as appropriate candidates for the F-8C research aircraft. Options on the basic configurations were included to cover variations in flight sensors, redundancy levels, data transmission techniques, processor input/output methods, and servo actuator arrangements. The study results can be applied to fly by wire systems for transport aircraft in general and the space shuttle.

Seacord, C. L.; Vaughn, D. K.

1976-01-01

182

Texture development in Galfenol wire  

NASA Astrophysics Data System (ADS)

Galfenol (Fe-Ga alloy) wire fabrication provides a low cost alternative to directional solidification methods. This work evaluates the compositional dependence of the wire drawing suitability of Fe-Ga and characterizes the microstructural and magnetic properties of these wires. Wire has been produced with Ga contents between 10 at. % and 17 at. % to allow determination of the ductile to brittle transition (DTBT) in wire manufacture. Published results on chill cast bend specimens indicated that a DTBT occurs at roughly 15 at. % Ga. This DTBT was observed under tensile loading with a corresponding change in fracture behavior from transverse fracture to intergranular fracture. For improved magnetostrictive performance, higher Ga contents are desired, closer to the 17 at. % Ga evaluated in this work. Electron backscattered diffraction B-H loop and resonance measurements as a function of magnetic field (to determine modulus and coupling factor) are presented for as-drawn, furnace, and direct current (DC) annealed wire. Galfenol wire produced via traditional drawing methods is found to have a strong <110> (?) texture parallel to the drawing direction. As-drawn wire was observed to have a lower magnetic permeability and larger hysteresis than DC annealed wire. This is attributed to the presence of a large volume of crystalline defects; such as vacancies and dislocations.

Boesenberg, A. J.; Restorff, J. B.; Wun-Fogle, M.; Sailsbury, H.; Summers, E.

2013-05-01

183

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

E-print Network

1 Policies for Climate Change in the long Run: Wiring up the Innovation System for Eco-innovation 1 system. The innovation system frame is only beginning to be caught up in environmental analysis by the "eco-innovation" concept. This paper suggests that the innovation system frame based on evolutionary

184

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.

2014-08-28

185

Comparative performance evaluation of advanced AC and DC EV propulsion systems  

NASA Astrophysics Data System (ADS)

Idaho National Engineering Laboratory (INEL) evaluates EV propulsion systems and components for the U.S. Department of Energy (DOE) Electric and Hybrid Vehicle (EHV) Program. In this study, experimental data were used to evaluate the relative performances of the benchmark Chrysler/GE ETV-1 DC and the Ford/GE First Generation Single-Shaft AC (ETX-I) propulsion systems. Tests were conducted on the INEL's chassis dynamometer using identical aerodynamic and rolling resistance road-load coefficients and vehicle test weights. The results allowed a direct comparison of selected efficiency and performance characteristics for the two propulsion system technologies. The ETX-I AC system exhibited slightly lower system efficiency during constant speed testing than the ETV-1 DC propulsion system.

MacDowall, R. D.; Crumley, R. L.

186

Graphite electrode DC arc furnace system for treatment of environmentally undesirable solid waste  

Microsoft Academic Search

Summary form only given. A graphite electrode DC arc furnance system has been used to demonstrate that iron basalt soil containing various surrogate nonradioactive materials found on the Department of Energy's atomic energy sites and hospital waste can be reduced to a compact, vitrified, solid material which is environmentally acceptable and will pass TCLP leachate tests. A second graphite electrode

C. H. Titus

1993-01-01

187

The Cabora Bassa D.C. Transmission System: Overvoltage Protection and Insulation Coordination  

Microsoft Academic Search

The Cabora Bassa-Apollo HVDC Transmission is the first UHV dc long distance transmission system using thyristor valves. The overvoltage protection and insulation co-ordination for the terminal stations of this systemaredescribed. It is shown, how the specific requirements of the thyristor valves for strict and reliable overvoltage protection have been solved by direct surge arrester protection with reasonable insulation levels of

W. Heise; U. Burger; J. Kauferle; D. Povh

1974-01-01

188

Integrated power conversion for DC power system by flying capacitor multi-level converter  

Microsoft Academic Search

In a modern electrical power system, most of equipments have dc terminals as an interface or inside of them, but the electric power is distributed by ac. Therefore, they have to employ a power converter suitable for their circumstances to trade the electric power. However, as the converters cannot avoid conversion losses inherently, it is important to reduce the number

M. Hojo; K. Minato

2010-01-01

189

Dynamic CT scanner environment effects on a DC electromagnetic tracking system  

E-print Network

Dynamic CT scanner environment effects on a DC electromagnetic tracking system Kirby Vosburgh Ph measurement is required. Gantry Off Electromagnetic Tracking Signals During a Typical CT Scan Cycle Purpose Electromagnetic (EM) trackers provide a steady stream of highly accurate data on instrument position, needing only

190

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

191

DC offset reduction in phase diversity heterodyne doppler radar system  

Microsoft Academic Search

Continuous wave Doppler radar systems have been used for non-contact detection of human cardiopulmonary activity, and these functions can be used in diverse applications including health care, emergency, military, or security. For reliable and robust sensing, several schemes are applied to overcome deleterious system sensitivity associated with the periodic phase relationship between the received signal and local oscillator. In previous

Byung-Kwon Park; Dragan Samardzija; Victor M. Lubecke; Olga Boric-Lubecke; Tod Sizer

2007-01-01

192

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

193

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

194

The key technologies of a distributed temperature monitoring system based on 1Wire bus  

Microsoft Academic Search

This paper focuses on improving the quality performance of 1-Wire bus which is mostly necessary to practice application. The key technology about 1-Wire bus that applies to DS18B20 and other 1-Wire bus serious manufactures is introduced in detail. The numbers of sensors hanging on 1-Wire bus are received according to the data bus driving ability and communication distance produced by

Chengliang Zhang; Xianying Feng; Lei Li

2010-01-01

195

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

196

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

197

Prospects of long-distance HTS DC power transmission systems  

NASA Astrophysics Data System (ADS)

Continual improvement of technologies for the safe use of power resources is a key to sustainable development of a human society. In particular, high-temperature superconductivity (HTS) should be used to meet the growing needs of the electric-power industry. It is known that HTS power cables allow us to increase the level of transmitted energy to several GW at voltage of 66-110 kV. HTS power cables of a coaxial design are almost ideal non-polluting system shielding electromagnetic field. In the present work we have tried to analyze various configurations of HTS power transmission systems, estimate the cable transmission capacitance depending on distance, and characterize reliability and efficiency of the systems.

Romashov, M. A.; Sytnikov, V. E.; Shakarian, Y. G.; Ivanov, Y. V.

2014-05-01

198

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

199

Point of collapse and continuation methods for large AC\\/DC systems  

Microsoft Academic Search

The implementation of both point of collapse (PoC) methods and continuation methods for the computation of voltage collapse points (saddle-node bifurcations) in large AC\\/DC power systems is described. The performance of these methods is compared for real systems of up to 2158 buses. Computational details of the implementation of the PoC and continuation methods are detailed, and the unique problems

C. A. Canizares; F. L. Alvarado

1993-01-01

200

Comparative performance evaluation of advanced AC and DC EV propulsion systems  

Microsoft Academic Search

Idaho National Engineering Laboratory (INEL) evaluates EV propulsion systems and components for the U.S. Department of Energy (DOE) Electric and Hybrid Vehicle (EHV) Program. In this study, experimental data were used to evaluate the relative performances of the benchmark Chrysler\\/GE ETV-1 DC and the Ford\\/GE First Generation Single-Shaft AC (ETX-I) propulsion systems. Tests were conducted on the INEL's chassis dynamometer

R. D. MacDowall; R. L. Crumley

1988-01-01

201

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

202

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

203

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

204

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

205

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

206

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

207

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

208

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

NASA Astrophysics Data System (ADS)

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.

1985-04-01

209

Genomewide identification of proteins secreted by the Hrp type III protein secretion system of Pseudomonas syringae pv. tomato DC3000  

Microsoft Academic Search

The ability of Pseudomonas syringae pv. tomato DC3000 to be pathogenic on plants depends on the Hrp (hypersensitive response and pathogenicity) type III protein secretion system and the effector proteins it translocates into plant cells. Through iterative application of experimental and computational techniques, the DC3000 effector inventory has been substantially enlarged. Five homologs of known avirulence (Avr) proteins and five

Tanja Petnicki-Ocwieja; David J. Schneider; Vincent C. Tam; Scott T. Chancey; Libo Shan; Yashitola Jamir; Lisa M. Schechter; Misty D. Janes; C. Robin Buell; Xiaoyan Tang; Alan Collmer; James R. Alfano

2002-01-01

210

Wire Maze  

NSDL National Science Digital Library

Learners create an electrical-circuit maze out of wire, then try to pass a paperclip through the maze without touching the wire. If the paper clip touches the wire, it closes the circuit, causing a light to come on or a buzzer to sound. This activity requires a basic understanding of how to build an electrical circuit.

Worcester Polytechnic Institute

2013-01-01

211

Investigation of Microelectromechanical Switches for Next Generation DC Power Distribution System  

NASA Astrophysics Data System (ADS)

This paper investigates the application of microelectromechanical system (MEMS) switches for DC power distribution system. Traditional electromechanical switches, solid state switches and solid state switch array are studied and simulated to understand their characteristics. Performance and characteristics of MEMS switches are reviewed and identified that electrostatically actuated MEMS switches are suitable for DC power applications. Scalable total cross tied (TCT) array configuration using MEMS switches has been proposed. The proposed configuration is suitable for variable voltage/current rating. Arc-less behavior of the switch configuration is analyzed using modified Paschen's curve. 400 V/6 A system is considered for the simulation and comparative study. The simulated result of the proposed MEMS switch array configuration is compared with the traditional switches. The comparative study shows that the proposed switch array configuration gives better performance in terms of voltage drop, leakage current, power loss, arc and size. This can be used in DC power system protection, circuit breaking, battery protection and smart grid load switching applications.

Femi, R.; Clement, Shibu; Agrawal, Anita; Prince, A. Amalin

2014-12-01

212

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

213

Wire core reactor for NTP  

NASA Technical Reports Server (NTRS)

The development of the wire core system for Nuclear Thermal Propulsion (NTP) that took place from 1963 to 1965 is discussed. A wire core consists of a fuel wire with spacer wires. It's an annular flow core having a central control rod. There are actually four of these, with beryllium solid reflectors on both ends and all the way around. Much of the information on the concept is given in viewgraph form. Viewgraphs are presented on design details of the wire core, the engine design, engine weight vs. thrust, a technique used to fabricate the wire fuel element, and axial temperature distribution.

Harty, R. B.

1991-01-01

214

Non-linear dc response in microwave-irradiated two-dimensional electron systems: interplay between ac and dc induced effects  

NASA Astrophysics Data System (ADS)

We study nonlinear dc response of a high-mobility two- dimensional electron system subject to microwave (ac) excitation and weak magnetic fields. Recent experiments [1] studied resistance at different dc excitations as a function of the ratio of the microwave frequency to the cyclotron frequency, . Here, we examine oscillations in microwave photoconductivity as a function of dc excitation, at different values of . We find that, for the most part, the oscillation period is the same as in the dark resistivity, and the phase is determined by microwave-induced oscillations at zero dc bias, consistent with the earlier results. However, at some excitation values previously associated with resistance maxima, this approach revealed resistance minima indicating saddle points in the resistivity. We further observed that the oscillation amplitude itself oscillates as a function of , with the oscillations strongly suppressed near half-integral values. These findings indicate the limitations of the simplified resonant condition proposed in Ref. 1 and might stimulate further theoretical studies. [1] W. Zhang, M.A. Zudov, L.N. Pfeiffer, and K.W. West, Phys. Rev. Lett. 98, 106804 (2007)

Hatke, Anthony; Zhang, Wenhao; Zudov, Michael; Pfeiffer, Loren; West, Ken

2008-03-01

215

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

216

The Newton-Raphson Load Flow Applied to AC\\/DC Systems with Commutation Impedance  

Microsoft Academic Search

Existing conditions in industrial ac-dc power systems may result in significant commutation resistances. If the resistance to reactance ratio of the commutation impedance is high, significant errors can result in load-flow studies which neglect the resistive portion. A method is presented for inclusion of a resistance-inductance fed bridge rectifier in a Newton-Raphson (N-R) load flow program. Polar form of the

Daniel J. Tylavsky; Frederick C. Trutt

1983-01-01

217

Reliability analysis of the F-8 digital fly-by-wire system  

NASA Technical Reports Server (NTRS)

The F-8 Digital Fly-by-Wire (DFBW) flight test program intended to provide the technology for advanced control systems, giving aircraft enhanced performance and operational capability is addressed. A detailed analysis of the experimental system was performed to estimated the probabilities of two significant safety critical events: (1) loss of primary flight control function, causing reversion to the analog bypass system; and (2) loss of the aircraft due to failure of the electronic flight control system. The analysis covers appraisal of risks due to random equipment failure, generic faults in design of the system or its software, and induced failure due to external events. A unique diagrammatic technique was developed which details the combinatorial reliability equations for the entire system, promotes understanding of system failure characteristics, and identifies the most likely failure modes. The technique provides a systematic method of applying basic probability equations and is augmented by a computer program written in a modular fashion that duplicates the structure of these equations.

Brock, L. D.; Goodman, H. A.

1981-01-01

218

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

219

Point of collapse methods applied to ac/dc power systems  

SciTech Connect

This paper describes an extension of the Point of Collapse method developed for ac systems studies to the determination of saddle-node bifurcations in power systems including high voltage direct current (HVDC) transmission. Bus voltage profiles are illustrated for an ac/dc test system, which significantly differ from the profiles of pure ac systems for typical system models. In particular, voltage dependent current order limits (VDCOLs) are shown to affect the voltage profiles (nose curves) and the loadability margin of the system. It is also shown that Hopf bifurcations, which are not possible in purely ac lossless systems with second-order generator models, become plausible when the dynamics for the HVDC system are included.

Canizares, C.A.; Alvarado, F.L.; DeMarco, C.L.; Dobson, I.; Long, W.F. (Wisconsin Univ., Madison, WI (United States))

1992-05-01

220

Mathematical model for the dc-ac inverter for the Space Shuttle  

NASA Technical Reports Server (NTRS)

The reader is informed of what was done for the mathematical modeling of the dc-ac inverter for the Space Shuttle. The mathematical modeling of the dc-ac inverter is an essential element in the modeling of the electrical power distribution system of the Space Shuttle. The electrical power distribution system which is present on the Space Shuttle is made up to 3 strings each having a fuel cell which provides dc to those systems which require dc, and the inverters which convert the dc to ac for those elements which require ac. The inverters are units which are 2 wire structures for the main dc inputs and 2 wire structures for the ac output. When 3 are connected together a 4 wire wye connection results on the ac side. The method of modeling is performed by using a Least Squares curve fitting method. A computer program is presented for implementation of the model along with graphs and tables to demonstrate the accuracy of the model.

Berry, Frederick C.

1987-01-01

221

Hardware model of a shipboard zonal electrical distribution system (ZEDS) : alternating current/direct current (AC/DC)  

E-print Network

A hardware model of a shipboard electrical distribution system based on aspects of the DDG 51 Flight IIA, Arleigh Burke class, 60Hz Alternating Current (AC) and the future direct current (DC), zonal electrical distribution ...

Tidd, Chad N. (Chad Norman)

2010-01-01

222

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

223

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

224

Stability of large DC power systems using switching converters, with application to the international space station  

NASA Technical Reports Server (NTRS)

As space direct current (dc) power systems continue to grow in size, switching power converters are playing an ever larger role in power conditioning and control. When designing a large dc system using power converters of this type, special attention must be placed on the electrical stability of the system and of the individual loads on the system. In the design of the electric power system (EPS) of the International Space Station (ISS), the National Aeronautics and Space Administration (NASA) and its contractor team led by Boeing Defense & Space Group has placed a great deal of emphasis on designing for system and load stability. To achieve this goal, the team has expended considerable effort deriving a dear concept on defining system stability in both a general sense and specifically with respect to the space station. The ISS power system presents numerous challenges with respect to system stability, such as high power, complex sources and undefined loads. To complicate these issues, source and load components have been designed in parallel by three major subcontractors (Boeing, Rocketdyne, and McDonnell Douglas) with interfaces to both sources and loads being designed in different countries (Russia, Japan, Canada, Europe, etc.). These issues, coupled with the program goal of limiting costs, have proven a significant challenge to the program. As a result, the program has derived an impedance specification approach for system stability. This approach is based on the significant relationship between source and load impedances and the effect of this relationship on system stability. This approach is limited in its applicability by the theoretical and practical limits on component designs as presented by each system segment. As a result, the overall approach to system stability implemented by the ISS program consists of specific hardware requirements coupled with extensive system analysis and hardware testing. Following this approach, the ISS program plans to begin construction of the world's largest orbiting power system in 1997.

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

1996-01-01

225

An Analysis of Sub Sea Electric Power Transmission Techniques from DC to AC 50\\/60 Hz and Beyond  

Microsoft Academic Search

In the past decade, the significant improvements in high speed, high voltage transistor technology enabled the design of more sophisticated sub sea electrical power transmission systems. This is the case of the power-electronics-based single wire DC and high frequency AC transmission systems that appeared as alternatives to the traditional three phase transmission systems. Although such advanced alternatives have been employed

Michael C. Wrinch; M. A. Tomim; J. Marti

2007-01-01

226

A new DC-side active filter for inverter power supplies compensates for unbalanced and nonlinear loads  

Microsoft Academic Search

A DC-side active filtering system for inverter power supplied is presented. The proposed system effectively nullifies the pulsating currents in the inverter input terminals as a result of unbalanced or nonlinear type loads. In the case of a three phase four wire inverter power supply the circulating zero sequence currents in the neutral are also nullified. The proposed system is

P. Enjeti; S. Kim

1991-01-01

227

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

228

Heat Leak Measurement of the 200 m Superconducting DC Power Transmission System at Chubu University  

NASA Astrophysics Data System (ADS)

The third cooling test of the 200 m superconducting DC power transmission system at Chubu University (CASER2) has been conducted from January to March 2011. During this term, the cooling of the system and the test of the liquid nitrogen circulation were performed. The temperature variation of the liquid nitrogen along the cryogenic pipe was measured and the heat leak from the surroundings at room temperature to the liquid nitrogen was estimated. The heat leakwas about275Wfor175mofthe cryogenicpipe, whichwas55%ofthevalue obtained duringthe ?rst cooling test. Further improvement will be continued to reduce the heat leak of CASER2.

Watanabe, Hirofumi; Ivanov, Yury; Sun, Jian; Hamabe, Makoto; Kawahara, Toshio; Yamaguchi, Satarou

229

Multiinput Direct DCAC Converter With High-Frequency Link for Clean Power-Generation Systems  

Microsoft Academic Search

This paper proposes a new topology for bidirectional multiinput direct dc-ac converter for clean-power-generation sys- tem, therefore, at the input port, a boost converter is used to meet the requirement of many distributed generation systems, such as photovoltaic, and fuel cell systems. The boost converter can in- crease the dc input voltage. This point results in a turn ratio re-

Mitra Sarhangzadeh; Seyed Hossein Hosseini; Mohammad Bagher Bannae Sharifian; Gevorg B. Gharehpetian

2011-01-01

230

Application of microprocessor-based controls in an ac/dc power conversion system  

NASA Astrophysics Data System (ADS)

A description is presented of the application of a microprocessor-based control system in an ac/dc power converter (or inverter). This control system was developed as one of the tasks in a program related to the application of power converters in a utility battery storage system. The program had the objective to design a system in which the microprocessor performs the supervisory control functions of a power converter, and provides closed-loop control of voltage and current by control of the thyristor gating pulses. Attention is given to a system description, the microprocessor-controlled thyristor gating, and the microprocessor closed-loop design. The reported investigation demonstrates the potential usefulness of a microprocessor-based control in power conversion systems, and provides a good base for continued exploration of microprocessor-based products and equipment.

Kovalsky, L. J.

231

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

NASA Technical Reports Server (NTRS)

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.

1992-01-01

232

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

233

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

234

On-grid and off-grid operation of multi-input single-output DC\\/DC converter based fuel cell generation system  

Microsoft Academic Search

This paper presents the modeling and simulation of a fuel cell generation unit for off-grid and on-grid operation and configuration. A fuel cell unit consists of a fuel cell array, DC\\/DC converter and DC\\/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented; also a multi-input DC\\/DC converter and its control scheme is proposed

R. Noroozian; M. Abedi; G. B. Gharehpetian; A. Bayat

2010-01-01

235

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

236

Solid State Remote Power Controllers for high voltage DC distribution systems  

NASA Technical Reports Server (NTRS)

Presently, hybrid Remote Power Controllers (RPC's) are in production and prototype units are available for systems utilizing 28VDC, 120VDC, 115VAC/400 Hz and 230VAC/400 Hz. This paper describes RPC development in a new area of application: HVDC distribution systems utilizing 270/300VDC. Two RPC current ratings, 1 amp and 2 amps, were selected for development as they are adequate to control 90% of projected system loads. The various aspects and trade-offs encountered in circuit development are discussed with special focus placed on the circuits that see the duress of the high dc potentials. The comprehensive evaluation tests are summarized which confirmed the RPC compliance with the specification and with system/load compatibility requirements. In addition, present technology status and new applications are summarized.

Billings, W. W.; Sundberg, G. R.

1977-01-01

237

Blind estimation of carrier frequency offset, I/Q imbalance and DC offset for OFDM systems  

NASA Astrophysics Data System (ADS)

Sensitivity to carrier frequency offset (CFO) is one of the biggest drawbacks of orthogonal frequency division multiplexing (OFDM) system. A lot of CFO estimation algorithms had been studied for compensation of CFO in OFDM system. However, with the adoption of direct-conversion architecture (DCA), which introduces additional impairments such as dc offset (DCO) and in-phase/quadrature (I/Q) imbalance in OFDM system, the established CFO estimation algorithms suffer from performance degradation. In our previous study, we developed a blind CFO, I/Q imbalance and DCO estimation algorithm for OFDM systems with DCA. In this article, we propose an alternative algorithm with reduced computation complexity and better accuracy. Performance of the proposed algorithm is demonstrated by simulations.

Liu, Tao; Li, Hanzhang

2012-12-01

238

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

239

A Calculation Method of DC-link Voltage Variation at Stepwise Change in Output Power of PWM Rectifier and Inverter System  

NASA Astrophysics Data System (ADS)

A calculation method of DC-link voltage variation of PWM rectifier-inverter system at a stepwise change in output power is proposed. The results of the calculation are confirmed by experiment. In addition, when the capacitance of DC-link is reduced, the parameters that have significant influence on the DC-link voltage variation are extracted.

Xu, Jin; Sato, Yukihiko

240

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

E-print Network

The unipolar induction DC circuit model, originally developed by Goldreich & 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 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 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 ultra-compact white dwarf binaries, we find that DC circuit 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, magnetic torque and dissipation are negligible, except possibly during the early T Tauri phase, when the stellar magnetic field is stronger than 10^3G.

Dong Lai

2012-06-17

241

Photosynthesis and antioxidant defense system of Gynura Bicolor DC grown at different elevated CO2 levels  

NASA Astrophysics Data System (ADS)

Atmospheric carbon dioxide concentration [CO _{2}] will increase in the future and will affect global climate and ecosystem productivity. However, this is not clearly an area that requires further study on the most appropriate [CO _{2}] selection for plant growth and quality in a closed, controlled environment. The aim of this study was to determine the variation of photosynthetic characteristics and antioxidant status under five CO _{2} concentration (400, 800, 1200, 2000 and 3000 umol mol (-1) ) on the leaf of Gynura bicolor DC. Here the results show that net photosynthetic rate(Pn), Chl content, edible biomass(EB), leaf blade width(LBW), root weight(RW), fructose(Fru) and sucrose(Suc) of Gynura bicolor DC increased under elevated [CO _{2}] of 800 umol mol (-1) , 1200 umol mol (-1) and 2000 umol mol (-1) . On the contrary, photosynthesis and biomass production declined significantly at 3000 umol mol (-1) CO _{2}, While Lipid peroxidation (LPO), malondialdehyde (MDA) and hydrogen peroxide (H _{2}O _{2}) achieved the highest levels. Furthermore, the contents of glutathione (GSH), vitamin C (VC), and vitamin E (VE), and total antioxidant capacity (T-AOC), the activity of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) reached the highest level at 2000 umol mol ({-1) }CO _{2}. Results imply that a significant increase in growth and antioxidant defense system of Gynura bicolor DC occurred under 800-2000 umol mol (-1) of CO _{2} concentration provided a theoretical basis for the application for plants selection in Bioregeneration Life Support System (BLSS) and a closed controlled environment.

Wang, Minjuan; Liu, Hong; Fu, Yuming

242

DC source assemblies  

DOEpatents

Embodiments of DC source assemblies of power inverter systems of the type suitable for deployment in a vehicle having an electrically grounded chassis are provided. An embodiment of a DC source assembly comprises a housing, a DC source disposed within the housing, a first terminal, and a second terminal. The DC source also comprises a first capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the first terminal. The DC source assembly further comprises a second capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the second terminal.

Campbell, Jeremy B; Newson, Steve

2013-02-26

243

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

244

Dense Spray Cooled DC-DC Converter  

Microsoft Academic Search

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

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

2006-01-01

245

Modelling of a DC arc furnace for optimal integration with the supply system  

Microsoft Academic Search

DC are furnaces have gained increasing favour with steel makers all over the world. DC arc furnaces have advantages over their conventional AC counterparts because of their greater supply-friendly nature. Although DC are furnaces still generate flicker, the stochastic component in their harmonics arc reduced and their demands on the supply network are much more compatible with the supply than

J. Bekker; P. H. Swart; C. F. Landy; D. A. Marshall

1995-01-01

246

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

247

Field Trial on a Rack-mounted DC Power Supply System with 80-Ah Lithium-ion Batteries  

NASA Astrophysics Data System (ADS)

Using an industrial lithium-ion battery that has higher energy density than conventional valve-regulated lead-acid batteries, a rack-mounted DC-power-supply system was assembled and tested at a base transceiver station (BTS) offering actual services. A nominal output voltage and maximum output current of the system is 53.5V and 20A, respectively. An 80-Ah lithium-ion battery composed of 13 cells connected in series was applied in the system and maintained in a floating charge method. The DC-power-supply system was installed in a 19-inch power rack in the telecommunications equipment box at BTS. The characteristics of the 80Ah lithium-ion battery, specifications of the DC-power-supply system and field-test results were shown in this paper.

Matsushima, Toshio

248

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

249

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$ (DOE) LANL: 200 k$ (DOE) UW: 200 k$ (DOE, AFOSR-MURI) #12;2 Superconductivity for Electric Systems Collaborations Characterization (Localized Texture, Jc Correlations) #12;3 Superconductivity for Electric Systems

250

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

E-print Network

. By connecting all the SQUIDs and all the feedback coils in series, this time domain multiplexed system requires and its feedback coil. Some time ago, we proposed a three-channel rf SQUID system with time domainA simple three-channel dc SQUID system using time domain multiplexing M. Mück and M. Korn Justus

Le Roy, Robert J.

251

Working with Systems and Thinking Systemically--Disentangling the Crossed Wires  

ERIC Educational Resources Information Center

This article explores two separate traditions that educational psychologists (EPs) in the UK have for working with systems. One of these is "systems work" with organisations such as schools. The other is "systemic thinking" for working with families. Over the years these two traditions, systems work and systemic thinking, have become crossed and

Fox, Mark

2009-01-01

252

Application of a one-wire digital temperature sensor in the monitoring system of a granary's temperature  

Microsoft Academic Search

A temperature monitoring system with characteristics of bus topology structure is made up of computer, interface adapter, bus driver, bus converter, transmission line and especially 1-wire digital temperature sensor DS18B20. Category 5 twisted-pair is used to form a tree-like or star-like network, in which more than 500 digital temperature sensors can be connected. Bus drivers and converters in network are

Hongtao Ma; Xiaojun Wang; Xiuqing Zhang

2009-01-01

253

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

254

Experimental Analysis of Voltage Drop Compensation in a DC Electrified Railway by Introducing an Energy Storage System Incorporating EDLCs  

NASA Astrophysics Data System (ADS)

Interest has been shown in the concept of an energy storage system aimed at leveling load and improving energy efficiency by charging during vehicle regeneration and discharging during running. Such a system represents an efficient countermeasure against pantograph point voltage drop, power load fluctuation and regenerative power loss. We selected an EDLC model as an energy storage medium and a step-up/step-down chopper as a power converter to exchange power between the storage medium and overhead lines. Basic verification was conducted using a mini-model for DC 400V, demonstrating characteristics suitable for its use as an energy storage system. Based on these results, an energy storage system was built for DC 600V and a verification test conducted in conjunction with the Enoshima Electric Railway Co. Ltd. This paper gives its experimental analysis of voltage drop compensation in a DC electrified railway and some discussions based on the test.

Konishi, Takeshi; Hase, Shin-Ichi; Nakamichi, Yoshinobu; Nara, Hidetaka; Uemura, Tadashi

255

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

256

Point of collapse and continuation methods for large ac/dc systems  

SciTech Connect

This paper describes the implementation of both Point of Collapse (PoC) methods and continuation methods for the computation of voltage collapse points (saddle-node bifurcations) in large ac/dc systems. A comparison of the performance of these methods is presented for real systems of up to 2,158 buses. The paper discusses computational details of the implementation of the PoC and continuation methods, and the unique challenges encountered due to the presence of high voltage direct current (HVDC) transmission, area interchange power control regulating transformers, and voltage and reactive power limits. The characteristics of a robust PoC power flow program are presented, and its application to detection and solution of voltage stability problems is demonstrated.

Canizares, C.A. (Escuela Politecnica Nacional, Quito (Ecuador)); Alvarado, F.L. (Univ. of Wisconsin, Madison, WI (United States))

1993-02-01

257

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

258

On the Feasibility of the Brushless DC (BLDC) Motor and Controller for 42V Automotive Cooling Fan System  

Microsoft Academic Search

The electrical power demand in automobiles is increasing steadily every year due to addition of new electrical systems that enhances passenger comfort and safety. The present in vehicle 14 V DC power system is being pushed to the maximum limits to meet the high power loads. In the mean time, the 42 V power network(\\

Jun-Hyuk Choi; In-Sung Jung; Jin Hur; Ha-Gyeong Sung; Byoung-Kuk Lee

2007-01-01

259

A Study of AC link and DC link Method for Wind Power Generation Connected to Electric Power System  

NASA Astrophysics Data System (ADS)

In this paper, grid-connected of the wind power generator was evaluated from viewpoint of the frequency fluctuation. The wind power generation system is the power generation method that depends on natural energy. Therefore, it is feared to exert a bad influence for the electric power quality. As a result, it is necessary to maintain a high electric power quality to do wind power generation in grid-connected. AC link method,AC-DC link method, and DC link method are enumerated by grid-connected of the wind power generator. The model system was constructed with the use of synchronous generator and induction generator as wind power generator, and the verification experiment was done. The verification experiments that use various grid-connected methods in each generator were conducted. As a result, the steadiest frequency characteristic was obtained in the DC link method. The result in which the stability level is especially the highest in the wind power generation system that adopted DC link method that used wound-rotor induction generator was obtained. Generally, induction generator have grid-connect by AC link method. Therefore, the effectiveness of grid-connected method of induction generator by DC link method could be proven when evaluating it from viewpoint of the frequency fluctuation.

Yukita, Kazuto; Washizu, Shinsuke; Nakano, Hiroyuki; Torii, Akihiro; Ueda, Akiteru; Goto, Yasuyuki; Ichiyanagi, Katsuhiro

260

System Design Considerations for High data Rate Communications Over Multi-wire Overhead Power-  

E-print Network

, PA 16802 Abstract ­ Broadband power-line communications over multi-wire overheard lines using for connecting private premises to a communication backbone. One promising technology, Broadband over Power-lines data rates. These theoretic facts are confirmed by means of computer simulations. Keywords - power-line

Kavehrad, Mohsen

261

A simulative building fire spread tracking system based on FPGA and 1-wire bus sensor network  

Microsoft Academic Search

In this paper, a simulative 1-wire bus sensor network dedicated to the experimental studies of building fire spread is proposed. The whole sensor network is capable of receiving commands from and exchanging data with FPGA (Field Programmable Gate Array) microprocessor, which is connected to host PC. Honeycomb-type layout, which enhances the measurement and tracking precision greatly, is adopted. And in

Shangli Xiao; Weisheng Xu; Youling Yu

2008-01-01

262

Study of maximum power tracking techniques and control of DC\\/DC converters for photovoltaic power system  

Microsoft Academic Search

As the electric power supplied by solar arrays depends on the insolation, temperature and array voltage, it is necessary to control the operating points to draw the maximum power of the solar array. The object of this paper is to investigate the maximum power tracking algorithms which were often used to compare the tracking efficiencies for the system operating under

Chihchiang Hua; Chihming Shen

1998-01-01

263

A system architecture for water quality monitoring system using wired sensors  

Microsoft Academic Search

This research paper proposes an aarchitecture for implementing a water quality monitoring system for the aquaculture industry. The system would enable monitoring of the water quality remotely via GSM. Conventional method used by aqua farms requires technical staff to visit ponds at designated time and perform manual testing on the water quality. Consequently, the technique consumes a lot of time

Nazleeni Samiha Haron; Mohd Khuzaimi B. Mahamad; Izzatdin Abdul Aziz; Mazlina Mehat

2008-01-01

264

Damping of a parallel ac-dc power system using PID power system stabilizers and rectifier current regulators  

SciTech Connect

A novel approach is presented to improve the dynamic stability of a parallel AC-DC power system. The developed scheme employs a proportional-integral-derivative (PID) power system stabilizer (PSS) and a PID rectifier current regulator (RCR) to enhance the damping for the electromagnetical mode of the system. The parameters of the proposed PID controllers are determined using a unified approach based on modal control theory. Eigenvalue analyses are performed for the system under various operating conditions in order to compare the damping effects provided by the two different control schemes. To demonstrate the effectiveness of the proposed damping schemes under disturbance conditions simulated dynamic response tests based on a nonlinear system model are also performed.

Hsu, Y.Y.; Wang, L. (Dept. of Electrical Engineering, National Taiwan Univ., Taipei (TW))

1988-09-01

265

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

266

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

267

Study of Wire Contact Resistance in Single and Multiwire Z-Pinch Experiments  

Microsoft Academic Search

Contact resistance of single and multi-wire array z-pinch has been measured for aluminum, stainless steel, and tungsten wires; diameters ranged from 7.5 to 30.5 micron. DC contact resistance in these experiments accounted for approximately 80% of load resistance, and resistance measurements varied from wire-to-wire by up to 15%. These DC measurements show that the resistance is highly dependent on both

M. R. Gomez; J. Zier; W. Tang; D. M. French; R. M. Gilgenbach; Y. Y. Lau; M. E. Cuneo; M. D. Johnston; M. G. Mazarakis; T. A. Mehlhorn

2007-01-01

268

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.

1997-01-01

269

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

270

Predictive diagnostic system for DC motor drives: Forest Products Project fact sheet  

Microsoft Academic Search

This report is a fact sheet on new sensor and control technology written for the NICE3 Program. ENVATEC has addressed a major problem for paper producers with its ENVAIR 4000, a sensor and control technology that optimizes DC motor drive operations by simultaneously monitoring and analyzing eight inputs on DC motors. Attributes, such as motor air temperature, speed, vibration, relative

2000-01-01

271

Power conditioning system with cascaded H-bridge multilevel converter DC-link voltage balancing method  

Microsoft Academic Search

Multilevel converters have become an attractive choice for high voltage and high power applications. One of the most popular multilevel converter topologies is the cascaded H-bridge converter. Besides its simplicity this topology requires separate DC sources. In electric drive applications these DC sources are normally performed by multi-winding transformers with diode rectifiers. In STATCOM or PWM rectifiers there is no

Marcin Zygmanowski; Boguslaw Grzesik; Jaroslaw Michalak

2011-01-01

272

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

273

Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS  

NASA Astrophysics Data System (ADS)

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2012-08-01

274

Anomalous nonadditive dispersion interactions in systems of three one-dimensional wires  

NASA Astrophysics Data System (ADS)

The nonadditive dispersion contribution to the binding energy of three one-dimensional (1D) wires is investigated using wires modeled by (i) chains of hydrogen atoms and (ii) homogeneous electron gases. We demonstrate that the nonadditive dispersion contribution to the binding energy is significantly enhanced compared with that expected from Axilrod-Teller-Muto-type triple-dipole summations and follows a different power-law decay with separation. The triwire nonadditive dispersion for 1D electron gases scales according to the power law d-β, where d is the wire separation, with exponents ? (rs) smaller than 3 and slightly increasing with rs from 2.4 at rs=1 to 2.9 at rs=10, where rs is the density parameter of the 1D electron gas. This is in good agreement with the exponent ? =3 suggested by the leading-order charge-flow contribution to the triwire nonadditivity, and is a significantly slower decay than the d-7 behavior that would be expected from triple-dipole summations.

Misquitta, Alston J.; Maezono, Ryo; Drummond, Neil D.; Stone, Anthony J.; Needs, Richard J.

2014-01-01

275

DC motor using multi activation wavelet network (MAWN) as an alternative to a PD controller in the robotics control system  

Microsoft Academic Search

In this paper, a robust MAWN is proposed. An application that constructs Wavelet Network as an alternative to a PD controller in the robotics control system with DC motor is fully investigated. Experimental results not only show that the target performance can be achieved by the proposed Wavelet Network, but also it outperforms the conventional PD controller. An literature survey

W. Emar; M. Dababneh; W. Johar

276

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

277

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

278

49 CFR 236.76 - Tagging of wires and interference of wires or tags with signal apparatus.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Tagging of wires and interference of wires or tags with signal apparatus. 236.76 Section...Systems Wires and Cables 236.76 Tagging of wires and interference of wires or tags with signal apparatus. Each...

2013-10-01

279

Hy-wire and fast electric field change measurements near an isolated thunderstorm, appendix C  

NASA Technical Reports Server (NTRS)

Electric field measurements near an isolated thunderstorm at 6.4 km distance are presented from both a tethered balloon experiment called Hy-wire and also from ground based fast and slow electric field change systems. Simultaneous measurements were made of the electric fields during several lightning flashes at the beginning of the storm which the data clearly indicate were cloud-to-ground flashes. In addition to providing a comparison between the Hy-wire technique for measuring electric fields and more traditional methods, these data are interesting because the lightning flashes occurred prior to changes in the dc electric field, although Hy-wire measured changes in the dc field of up to 750 V/m in the direction opposite to the fair weather field a short time later. Also, the dc electric field was observed to decay back to its preflash value after each flash. The data suggest that Hy-wire was at the field reversal distance from this storm and suggest the charge realignment was taking place in the cloud with a time constant on the order of 20 seconds.

Holzworth, R. H.; Levine, D. M.

1983-01-01

280

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

281

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

282

Novel three-component Rieske non-heme iron oxygenase system catalyzing the N-dealkylation of chloroacetanilide herbicides in sphingomonads DC-6 and DC-2.  

PubMed

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; He, Jian; Li, Shun-Peng

2014-08-01

283

A new circuit design and control to reduce input harmonic current for a three-phase ac machine drive system having a very small dc-link capacitor  

Microsoft Academic Search

This paper presents a new circuit topology to meet the input harmonic current standard for an ac machine drive system which has a very small dc-link capacitor. The proposed circuit topology is based on a harmonic current injection method, and it keeps up size and cost competitiveness of an ac machine drive system having a very small dc-link capacitor. Also,

Hyunjae Yoo; Seung-Ki Sul

2010-01-01

284

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

285

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

286

Study of Wire Contact Resistance in Single and Multi-wire Z-Pinch Experiments  

NASA Astrophysics Data System (ADS)

Contact resistance of single and multi-wire array z-pinch has been measured for aluminum, stainless steel, and tungsten wires; diameters ranged from 7.5 to 30.5 micron. DC contact resistance in these experiments accounted for approximately 80% of load resistance, and resistance measurements varied from wire-to-wire by up to 15%. These DC measurements show that the resistance is highly dependent on both the wire material and the mass of the wire weights (0.8 g to 3.6 g). Marx pulses of 120 kV, 18 kA, 150 ns risetime were applied to the z-pinch. Wire plasma expansion velocity was measured using a streak camera, and expansion profile of the wires was determined using laser schlieren imaging. Electron temperature of individual wire plasmas is being determined by visible/UV spectra. Results will be presented of several methods being explored to reduce the contact resistance. *This work was supported by U. S. DoE through Sandia National Laboratories award number 240985 to the University of Michigan. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

Gomez, M. R.; Zier, J.; Tang, W.; French, D. M.; Gilgenbach, R. M.; Lau, Y. Y.; Cuneo, M. E.; Johnston, M. D.; Mazarakis, M. G.; Mehlhorn, T. A.

2007-11-01

287

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

288

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

2012-08-29

289

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 510^?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

290

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

291

Analysis of a dc bus system with a nonlinear constant power load and its delayed feedback control.  

PubMed

This paper tackles a destabilizing problem of a direct-current (dc) bus system with constant power loads, which can be considered a fundamental problem of dc power grid networks. The present paper clarifies scenarios of the destabilization and applies the well-known delayed-feedback control to the stabilization of the destabilized bus system on the basis of nonlinear science. Further, we propose a systematic procedure for designing the delayed feedback controller. This controller can converge the bus voltage exactly on an unstable operating point without accurate information and can track it using tiny control energy even when a system parameter, such as the power consumption of the load, is slowly varied. These features demonstrate that delayed feedback control can be considered a strong candidate for solving the destabilizing problem. PMID:25353544

Konishi, Keiji; Sugitani, Yoshiki; Hara, Naoyuki

2014-02-01

292

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

293

Design and Control of a Multiple Input DC\\/DC Converter for Battery\\/Ultra-capacitor Based Electric Vehicle Power System  

Microsoft Academic Search

Battery\\/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC\\/DC converter, to regulate output voltage from different inputs. The proposed multi-input converter is capable of bi-directional operation and is responsible for power diversification and optimization. A fixed switching frequency strategy is considered

Zhihao Li; Omer Onar; Alireza Khaligh; Erik Schaltz

2009-01-01

294

A fully-integrated 130nm CMOS DC-DC step-down converter, regulated by a constant on\\/off-time control system  

Microsoft Academic Search

A fully-integrated DC-DC step-down converter in a 130 nm 1.2 V CMOS technology is realized, with an integrated metal-track inductor and integrated MOS and MIM capacitors. The converter is designed to generate an output voltage of 1.2 V out of a 2.6 V power supply. No external components are required. The maximum power conversion efficiency is 52%, for a voltage

Mike Wens; Michiel Steyaert

2008-01-01

295

Precision wire feeder for small diameter wire  

DOEpatents

A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

1992-08-11

296

Precision wire feeder for small diameter wire  

DOEpatents

A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

Brandon, Eldon D. (Albuquerque, NM); Hooper, Frederick M. (Albuquerque, NM); Reichenbach, Marvin L. (Albuquerque, NM)

1992-01-01

297

Diverse strategies engaged in establishing stereotypic wiring patterns among neurons sharing a common input at the visual system's first synapse.  

PubMed

Sensory circuits use common strategies, such as convergence and divergence, typically at different synapses, to pool or distribute inputs. Inputs from different presynaptic cell types converge onto a common postsynaptic cell, acting together to shape neuronal output (Klausberger and Somogyi, 2008). Also, individual presynaptic cells contact several postsynaptic cell types, generating divergence of signals. Attaining such complex wiring patterns relies on the orchestration of many events across development, including axonal and dendritic growth and synapse formation and elimination (reviewed by Waites et al., 2005; Sanes and Yamagata, 2009). Recent work has focused on how distinct presynaptic cell types form stereotypic connections with an individual postsynaptic cell (Morgan et al., 2011; Williams et al., 2011), but how a single presynaptic cell type diverges to form distinct wiring patterns with multiple postsynaptic cell types during development remains unexplored. Here we take advantage of the compactness of the visual system's first synapse to observe development of such a circuit in mouse retina. By imaging three types of postsynaptic bipolar cells and their common photoreceptor targets across development, we found that distinct bipolar cell types engage in disparate dendritic growth behaviors, exhibit targeted or exploratory approaches to contact photoreceptors, and adhere differently to the synaptotropic model of establishing synaptic territories. Furthermore each type establishes its final connectivity patterns with the same afferents on separate time scales. We propose that such differences in strategy and timeline could facilitate the division of common inputs among multiple postsynaptic cell types to create parallel circuits with diverse function. PMID:22836264

Dunn, Felice A; Wong, Rachel O L

2012-07-25

298

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

299

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

PubMed Central

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

300

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

301

The automated dc parameter testing of GaAs MESFETs using the Singer automatic integrated circuit test system  

Microsoft Academic Search

Procedures were developed to automate the manual testing of the DC parameters of GaAs MESFETs, integrated resistors and Schottky diodes. These devices are elements of a NAND\\/NOR logic circuit developed by Hewlett-Packard. The Singer Automatic Integrated Circuit Test System located at the Air Force Wright Aeronautical Laboratories, Avionics Laboratory (AFWAL\\/AADE), Wright-Patterson AFB, OH, was used to develop these procedures. The

T. L. Harper

1980-01-01

302

High efficiency bidirectional LLC resonant converter for 380V DC power distribution system using digital control scheme  

Microsoft Academic Search

A bidirectional full-bridge LLC resonant converter with a new symmetric LLC-type resonant network using a digital control scheme is proposed for a 380V dc power distribution system. This converter can operate under high power conversion efficiency since the symmetric LLC resonant network has zero voltage switching capability for primary power switches and soft commutation capability for output rectifiers. In addition,

Jee-Hoon Jung; Ho-Sung Kim; Jong-Hyun Kim; Myoung-Hyo Ryu; Ju-Won Baek

2012-01-01

303

Dynamic model and control of AC-DC-AC voltage-sourced converter system for distributed resources  

Microsoft Academic Search

This paper introduces a dynamic model of the AC-DC-AC voltage-sourced converter (VSC) system which provides a linear relationship between the input and output variables. The model is developed in two steps. First, the exact abc frame switched model of a VSC is transformed to a Switching Reference Frame (SRF). Then, the SRF model is transformed to an appropriate dqO reference

H. Nikkhajoei; R. Iravani

2008-01-01

304

Dynamic Model and Control of ACDCAC Voltage-Sourced Converter System for Distributed Resources  

Microsoft Academic Search

This paper introduces a dynamic model of the ac-dc-ac voltage-sourced converter (VSC) system which provides a linear relationship between the input and output variables. The model is developed in two steps. First, the exact abc frame switched model of a VSC is transformed to a switching reference frame (SRF). Then, the SRF model is transformed to an appropriate dq0 reference

H. Nikkhajoei; R. Iravani

2007-01-01

305

Milliwatt dc/dc Inverter  

NASA Technical Reports Server (NTRS)

Compact dc/dc inverter uses single integrated-circuit package containing six inverter gates that generate and amplify 100-kHz square-wave switching signal. Square-wave switching inverts 10-volt local power to isolated voltage at another desired level. Relatively high operating frequency reduces size of filter capacitors required, resulting in small package unit.

Mclyman, C. W.

1983-01-01

306

Generation of voltage fluctuations in power systems with DC arc furnaces  

Microsoft Academic Search

There is an increasing use of high-power DC arc furnaces for scrap melting all over the world. Onsite measurements in several steel plants with these furnaces have shown that flicker relevant voltage fluctuations cannot be prevented. The first reason is the time-varying need of reactive power. Also dynamic compensators like TCRs are often not able to avoid considerable flicker, particularly

D. Stade; H. Schau; M. Malsch; J. Hunermund; S. Prinz

1998-01-01

307

A New DC Model for Transmission Loss Allocations in Power Systems  

Microsoft Academic Search

Under open access environment in the era of deregulated power industry, transmis- sion loss allocation to various transactions is one of the important issues to be solved exactly. Because of the non-linear nature of power flow and power loss, it is very dif- ficult to segregate and to allocate losses among the participants properly. This paper presents a New DC

M. H. Kabir

2007-01-01

308

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

309

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

310

Radiation effects on DC-DC Converters  

NASA Technical Reports Server (NTRS)

DC-DC switching converters are circuits that can be used to convert a DC voltage of one value to another by switching action. They are increasing being used in space systems. Most of the popular DC-DC switching converters utilize power MOSFETs. However power MOSFETs, when subjected to radiation, are susceptible to degradation of device characteristics or catastrophic failure. This work focuses on the effects of total ionizing dose on converter performance. Four fundamental switching converters (buck converter, buck-boost converter, cuk converter, and flyback converter) were built using Harris IRF250 power MOSFETs. These converters were designed for converting an input of 60 volts to an output of about 12 volts with a switching frequency of 100 kHz. The four converters were irradiated with a Co-60 gamma source at dose rate of 217 rad/min. The performances of the four converters were examined during the exposure to the radiation. The experimental results show that the output voltage of the converters increases as total dose increases. However, the increases of the output voltage were different for the four different converters, with the buck converter and cuk converter the highest and the flyback converter the lowest. We observed significant increases in output voltage for cuk converter at a total dose of 24 krad (si).

Zhang, Dexin; Attia, John O.; Kankam, Mark D. (Technical Monitor)

2000-01-01

311

NASA wiring for space applications program  

NASA Technical Reports Server (NTRS)

An overview of the NASA Wiring for Space Applications Program and its relationship to NASA's space technology enterprise is given in viewgraph format. The mission of the space technology enterprise is to pioneer, with industry, the development and use of space technology to secure national economic competitiveness, promote industrial growth, and to support space missions. The objectives of the NASA Wiring for Space Applications Program is to improve the safety, performance, and reliability of wiring systems for space applications and to develop improved wiring technologies for NASA flight programs and commercial applications. Wiring system failures in space and commercial applications have shown the need for arc track resistant wiring constructions. A matrix of tests performed versus wiring constructions is presented. Preliminary data indicate the performance of the Tensolite and Filotex hybrid constructions are the best of the various candidates.

Schulze, Norman

1995-01-01

312

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

313

COBRA-STAR, a five frame point-projection x-ray imaging system for 1 MA scale wire-array Z pinches  

NASA Astrophysics Data System (ADS)

A new imaging system for 1MA 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 10.2to30?m in the five X pinches. Typical images have a 168mm2 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 3-5keV. 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 0.015to1.1?m 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?m spatial resolution.

Douglass, J. D.; Hammer, D. A.

2008-03-01

314

Trail Systems as fault tolerant wires and their use in bio-processors Nicolas GLADE  

E-print Network

.glade@imag.fr 1In order to differentiate them from any multi-agent system, the agents of a trail system of various nature and at different scales. The heterogeneous set of natural or artificially designed systems

Paris-Sud XI, Université de

315

Photovoltaic powered 20-hp DC/AC irrigation system and a 3-kW nitrogen generator  

SciTech Connect

A 25-kWp photovoltaic power system has been providing power for irrigation and crop drying since July 1977 at an agricultural field station of the University of Nebraska, located at Mead, Nebraska. The system was designed and built by Massachusetts Institute of Technology's Lincoln Laboratory under US Department of Energy sponsorship and is being operated jointly by the university and MIT Lincoln Laboratory. The system consists of a 25-kWp PV array, a battery subsystem, a power dump, an inverter, a controller and a data acquisition system. This photovoltaic power system has been used as a test facility in order to test and evaluate a variety of PV-related agricultural applications, including irrigation, crop drying and fertilizer manufacturing. Two interesting applications presently under evaluation are a 20-hp DC/AC-powered irrigation system and an on-site nitrogen fertilizer production unit.

Hopkinson, R.F.

1980-01-01

316

30 CFR 77.902-2 - Approved ground check systems not employing pilot check wires.  

Code of Federal Regulations, 2010 CFR

... Low- and Medium-Voltage Alternating Current Circuits 77.902-2 Approved ground check systems...been determined that the system includes a fail safe design causing the circuit breaker to open when ground continuity is...

2010-07-01

317

30 CFR 75.902-2 - Approved ground check systems not employing pilot check wires.  

Code of Federal Regulations, 2010 CFR

...Underground Low- and Medium-Voltage Alternating Current Circuits 75.902-2 Approved ground check systems...is determined that the system includes a fail safe design causing the circuit breaker to open when ground continuity is...

2010-07-01

318

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

319

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

320

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

321

Can an AC (alternating current) electrical system replace the present DC system in the automobile? An investigative feasibility study. II. Comparison and tradeoffs  

Microsoft Academic Search

For Part I see ibid., vol.47, no.3, p.1072-80 (1998). In Part I of this paper, the possibility of using an AC (alternating current) electrical system instead of the present DC system in the automobile was discussed. The various possible architectures were described in Part I. Part II continues with the issues of various tradeoffs related to cost, size, and overall

M. Abul Masrur; Daryl S. Sitar; V. A. Sankaran

1998-01-01

322

A Simplified Cascade Current Source Inverter Interconnected to Single-Phase Three-Wire Distribution System and Its Application to Electric Energy Storage System with Batteries  

NASA Astrophysics Data System (ADS)

A novel current source inverter system interconnected to the single-phase grid is proposed. It has the same construction as the conventional three-phase current source inverter that is interconnected to the single-phase three-wire distribution system. Though the proposed circuit has no output transformer, it can be equivalently performed as the single-phase double cascade inverter by diverting the pole transformer in the utility system. By controlling the appropriate scheme, the output currents can be obtained as the five-level waveforms and their distortions can be decreased sufficiently. It is applied to the interactive electric energy storage system with batteries and the basic discharging characteristics are discussed experimentally.

Iwata, Syuichi; Masukawa, Shigeo; Iida, Shoji

323

Application of a one-wire digital temperature sensor in the monitoring system of a granary's temperature  

NASA Astrophysics Data System (ADS)

A temperature monitoring system with characteristics of bus topology structure is made up of computer, interface adapter, bus driver, bus converter, transmission line and especially 1-wire digital temperature sensor DS18B20. Category 5 twisted-pair is used to form a tree-like or star-like network, in which more than 500 digital temperature sensors can be connected. Bus drivers and converters in network are composed of low-cost 74HC series logic ICs which has a very low static power consumption and high performance, so they can be powered through the sensor bus and make installation, maintenance, and expansion of system very convenient. Because of hardware fault-tolerant technology used by bus driver and converter circuits, the fault sensor branch or branch bus can automatically detach from the main bus and will not affect normal working of other sensors in network, so to solve the problem of a certain sensor or branch's damage causing the paralysis of entire bus. The length of sensor bus can extend to more than 1000 meters. It is very suitable for the multi-point temperature monitoring sites where the detected points are relative concentrated such as food storage, vegetables greenhouses and so on.

Ma, Hongtao; Wang, Xiaojun; Zhang, Xiuqing

2009-07-01

324

Control System for Readout Electronics of Multi-Channel Magnetocardiographs Using High-Temperature DC Superconducting Quantum Interference Devices  

NASA Astrophysics Data System (ADS)

We aimed to develop a control system for multichannel magnetocardiography (MCG) based on a high-temperature DC superconducting quantum interference device (high-Tc SQUID). To create this system, we used one oscillator as an AC bias controller to operate a multichannel high-Tc SQUID. To optimize the SQUID parameters (such as the AC bias, offset voltage), two new control sequences based on a cross-correlation method and a fast Fourier transform method were developed. Using the AC bias controller and the sequences, the typical white noise level of the SQUID was about 50--60 fT Hz-1/2 around 100 Hz. Multichannel MCG signals were detected clearly in the system with the SQUIDs. We conclude that our control system with one oscillator and new protocols can reliably operate a multichannel SQUID.

Kandori, Akihiko; Suzuki, Daisuke; Tsukamoto, Akira; Kumagai, Yukio; Miyashita, Tsuyoshi; Ogata, Kuniomi; Seki, Yusuke; Yokosawa, Koichi; Tsukada, Keiji

2005-09-01

325

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

326

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

327

Cipher Printing Telegraph Systems For Secret Wire and Radio Telegraphic Communications  

Microsoft Academic Search

This paper describes a printing telegraph cipher system devetoped during the World War for the use of the Signal Corps, U. S. Army. This system is so designed that the messages are in secret form from the time they leave the sender until they are deciphered automatically at the office of the addressee. If copied while en route, the messages

G. S. Vernam

1926-01-01

328

A Novel N-Input Voting Algorithm for X-by-Wire Fault-Tolerant Systems  

PubMed Central

Voting is an important operation in multichannel computation paradigm and realization of ultrareliable and real-time control systems that arbitrates among the results of N redundant variants. These systems include N-modular redundant (NMR) hardware systems and diversely designed software systems based on N-version programming (NVP). Depending on the characteristics of the application and the type of selected voter, the voting algorithms can be implemented for either hardware or software systems. In this paper, a novel voting algorithm is introduced for real-time fault-tolerant control systems, appropriate for applications in which N is large. Then, its behavior has been software implemented in different scenarios of error-injection on the system inputs. The results of analyzed evaluations through plots and statistical computations have demonstrated that this novel algorithm does not have the limitations of some popular voting algorithms such as median and weighted; moreover, it is able to significantly increase the reliability and availability of the system in the best case to 2489.7% and 626.74%, respectively, and in the worst case to 3.84% and 1.55%, respectively. PMID:25386613

Karimi, Abbas; Zarafshan, Faraneh; Al-Haddad, S. A. R.; Ramli, Abdul Rahman

2014-01-01

329

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.

2008-08-11

330

A Wire Position Monitor (WPM) System to Control the Cold Mass Movements inside the TTF Cryomodule  

NASA Astrophysics Data System (ADS)

A system able to measure, on-line, movements and vibrations of the Cold Mass (CM) during cool down and steady state operation has been developed and installed inside the first TTF Cryomodule. The system includes two indipendent lines, with 18 WPMs each, and an improved version of BPM type read out and data analysis. Laboratory tests on a shorter prototype have shown that the system is able to monitor the CM displacements with a micron sensitivity, the absolut error being less than 10 microns in the range of +/- 2.5 mm. Fast read out and FFT technique allow also to detect and analyze eventual CM vibrations. In this paper we present the system together with the experimental results obtained during the first cool down of the cryomodule.

Bosotti, Angelo; Giove, Dario; Pagani, Carlo; Varisco, Giuseppe

1997-05-01

331

The Virtual Wires Emulation System: A Gate-Efficient ASIC Prototyping Environment  

Microsoft Academic Search

FPGA-based ASIC development systems have become importanttools in contemporary ASIC design. Existing systemsexhibit low per-FPGA gate utilization (10 to 20 percent)due to limited inter-chip communication. Attempts at overcomingthis limitation through the use of high dimensionalinterconnection topologies have met with limited success.This paper focuses on the prototype hardware and softwareinterfaces that have been developed for an FPGA-basedASIC emulation system based on

Russell Tessier; Jonathan Babb; Matthew Dahl; Silvina Hanono; David Hoki

1994-01-01

332

Plated wire memory subsystem  

NASA Technical Reports Server (NTRS)

The design, construction, and test history of a 4096 word by 18 bit random access NDRO Plated Wire Memory for use in conjunction with a spacecraft input/output and central processing unit is reported. A technical and functional description is given along with diagrams illustrating layout and systems operation. Test data is shown on the procedures and results of system level and memory stack testing, and hybrid circuit screening. A comparison of the most significant physical and performance characteristics of the memory unit versus the specified requirements is also included.

Carpenter, K. H.

1974-01-01

333

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

Su-Negre, Josep M; Roig, Manel; Fuster, Roser; Hernndez, Carmen; Ruh, Ramon; Garca-Montoya, Encarna; Prez-Lozano, Pilar; Miarro, Montserrat; Tic, Josep R

2014-08-15

334

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

335

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

336

Interference characteristics of broadband power line communication systems using aerial medium voltage wires  

Microsoft Academic Search

The promise of broadband power line (BPL) communications - broadband access to virtually every home in the United States - remains unfulfilled if the radio emissions from these systems cause significant harmful interference to other users of the wireless spectrum. This article presents an elementary analysis of the physical mechanisms underlying these emissions, from which the interference characteristics of BPL

P. S. Henry

2005-01-01

337

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

338

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

339

FC/Battery Power Management for Electric Vehicle Based Interleaved dc-dc Boost Converter Topology  

E-print Network

FC/Battery Power Management for Electric Vehicle Based Interleaved dc- dc Boost Converter Topology.fr Keywords Fuel cell System (FCS), Electric vehicle, Energy management, Interleaved Boost DC-DC Converter (FC for electric vehicle may not be feasible to satisfy the peak demand changes especially during accelerations

Paris-Sud XI, Université de

340

An hybrid wireless-wired monitoring system for real-time rock collapse forecasting  

Microsoft Academic Search

Rock face collapses are one of the most dangerous and sudden natural risks in mountain environments. Traditional investigation techniques (e.g., strain gauge, inclinometer) cannot guarantee neither a non-invasive monitoring within the rocks nor a prompt alarm in case of possible collapse. Real-time monitoring systems, which might provide an effective evaluation of the dynamics of the phenomenon for a subsequent forecasting

Cesare Alippi; Romolo Camplani; Cristian Galperti; Antonio Marullo; Manuel Roveri

2010-01-01

341

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

Microsoft Academic Search

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

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

2002-01-01

342

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

343

Active filtering of harmonic currents in three-phase, four-wire systems with three-phase and single-phase nonlinear loads  

Microsoft Academic Search

A novel active harmonic-neutralizing filter is proposed which eliminates current harmonic effects, caused by any configuration of nonlinear loads in a three-phase, four-wire systems. The authors present proposed filter topologies and simulation results verifying the concept. Theoretical analysis of the circuit is included to facilitate a detailed converter design. The proposed topology is shown to have distinct advantages over traditional

Conor A. Quinn; Ned Mohan

1992-01-01

344

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

345

A Wire Position Monitor System for the 1.3 FHZ Tesla-Style Cryomodule at the Fermilab New-Muon-Lab Accelerator  

SciTech Connect

The first cryomodule for the beam test facility at the Fermilab New-Muon-Lab building is currently under RF commissioning. Among other diagnostics systems, the transverse position of the helium gas return pipe with the connected 1.3 GHz SRF accelerating cavities is measured along the {approx}15 m long module using a stretched-wire position monitoring system. An overview of the wire position monitor system technology is given, along with preliminary results taken at the initial module cooldown, and during further testing. As the measurement system offers a high resolution, we also discuss options for use as a vibration detector. An electron beam test facility, based on superconducting RF (SRF) TESLA-style cryomodules is currently under construction at the Fermilab New-Muon-Lab (NML) building. The first, so-called type III+, cryomodule (CM-1), equipped with eight 1.3 GHz nine-cell accelerating cavities was recently cooled down to 2 K, and is currently under RF conditioning. The transverse alignment of the cavity string within the cryomodule is crucial for minimizing transverse kick and beam break-up effects, generated by the high-order dipole modes of misaligned accelerating structures. An optimum alignment can only be guaranteed during the assembly of the cavity string, i.e. at room temperatures. The final position of the cavities after cooldown is uncontrollable, and therefore unknown. A wire position monitoring system (WPM) can help to understand the transverse motion of the cavities during cooldown, their final location and the long term position stability after cryo-temperatures are settled, as well as the position reproducibility for several cold-warm cycles. It also may serve as vibration sensor, as the wire acts as a high-Q resonant detector for mechanical vibrations in the low-audio frequency range. The WPM system consists out of a stretched-wire position detection system, provided with help of INFN-Milano and DESY Hamburg, and RF generation and read-out electronics, developed at Fermilab.

Eddy, N.; Fellenz, B.; Prieto, P.; Semenov, A.; Voy, D.C.; Wendt, M.; /Fermilab

2011-08-17

346

Transport Through Carbon Nanotube Wires  

NASA Technical Reports Server (NTRS)

This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

Anantram, M. P.; Kwak, Dochan (Technical Monitor)

2001-01-01

347

Universal dc signal conditioner  

NASA Technical Reports Server (NTRS)

Signal conditioner was designed which can condition dc signals over range of + or - volts. It is lighter, has lower initial and maintenance costs, and higher reliability than conventional discrete circuit designs. System incorporates linear integrated circuits in conjunction with hybrid, thin film circuit technology to achieve high degree of circuit miniaturization.

Bradanini, P. A.

1972-01-01

348

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

349

Seamless integration of 100-G wire line and 100-GHz wireless link system  

NASA Astrophysics Data System (ADS)

In this invited paper, we experimentally demonstrate a seamlessly integrated fiber-wireless system that delivers 108-Gb/s signal through 80-km fiber and 1-m wireless transport over free-space at 100 GHz, adopting polarization-divisionmultiplexing quadrature-phase-shift-keying (PDM-QPSK) modulation and heterodyning coherent detection. The X- and Y-polarization baseband components of the optical PDM-QPSK are simultaneously up-converted to 100-GHz wireless carriers by optical polarization-diversity heterodyne beating, and then independently transmitted and received by two pairs of transmitter and receiver antennas, which forms a 2x2 multiple-input multiple-output (MIMO) wireless link. At the wireless receiver, two-stage down conversion is performed with firstly done in analog domain based on balanced mixer and sinusoidal radio frequency (RF) signal, and then in digital domain based on digital signal processing (DSP). MIMO signal de-multiplexing combined with optical polarization multiplexing and free space MIMO crosstalk is realized by constant modulus algorithm (CMA) in digital signal processing (DSP) part at the receiver. The bit-error ratio (BER) for the 108-Gb/s PDM-QPSK signal is less than the pre-forward-error-correction (pre-FEC) threshold of 3.8x10-3 after both 1-m wireless delivery at 100 GHz and 80-km single-mode fiber-28 (SMF-28) transmission. To our knowledge, this is the first demonstration to realize 100-Gb/s signal delivery through both fiber and wireless links at 100GHz.

Dong, Ze; Yu, Jianjun; Li, Xinying; Chi, Nan

2013-01-01

350

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

351

A flyback-type single phase utility interactive inverter with low-frequency ripple current reduction on the DC input for an AC photovoltaic module system  

Microsoft Academic Search

In recent years, interest in natural energy has grown because of increased environmental concerns. Many kinds of inverter circuits and their control schemes for photovoltaic (PV) power generation systems have been studied. In a conventional system, the PV array in which many PV modules are connected in series is used to obtain sufficient DC-bus voltage for generating an AC utility

Toshihisa Shimizu; Keiji Wada; Naoki Nakamura

2002-01-01

352

Creating order with nature: transatlantic transfer of ideas in park system planning in twentieth?century Washington D.C., Chicago, Berlin and Rome  

Microsoft Academic Search

Municipal park systems played an important role in the comprehensive city plans that were developed on both sides of the Atlantic at the beginning of the twentieth century, for example in Washington D.C., Chicago, Berlin and Rome. Using these cities as examples, the article shows how open space planning and design crossed national borders. Park systems in the USA attracted

Sonja Duempelmann

2009-01-01

353

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

354

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

355

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

356

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

357

A practical monitoring system for the structural safety of mega-trusses using wireless vibrating wire strain gauges.  

PubMed

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

358

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

359

Laser Wire Stripper  

NASA Technical Reports Server (NTRS)

NASA-developed space shuttle technology is used in a laser wire stripper designed by Raytheon Company. Laser beams cut through insulation on a wire without damaging conductive metal, because laser radiation that melts plastic insulation is reflected by the metal. The laser process is fast, clean, precise and repeatable. It eliminates quality control problems and the expense of rejected wiring.

1983-01-01

360

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

361

Effect of magnetic field strength on deposition rate and energy flux in a dc magnetron sputtering system  

SciTech Connect

Variations in the magnetic field strongly affect the plasma parameters in a magnetron sputtering system. This in turn affects the throughput as well as the energy flux to the substrate. The variation in the magnetic field in this study, for a dc magnetron process, is achieved by shifting the magnet assembly slightly away from the target. Measurements of the plasma parameters show that while the electron density at the substrate increases with decrease in magnetic field, the electron temperature decreases. The cooling of the electron temperature is consistent with results reported elsewhere. The deposition rate per input magnetron power is found to increase slightly with the decrease in magnetic field for the process conditions considered in this study. Results suggest that the energy flux to the substrate tends to show a general decrease with the shift in the magnet assembly.

Ekpe, Samuel D.; Jimenez, Francisco J.; Field, David J.; Davis, Martin J.; Dew, Steven K. [Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); NUCRYST Pharmaceuticals, 10102-114 st., Fort Saskatchewan, Alberta T8L 3W4 (Canada); Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)

2009-11-15

362

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

363

DC-X proving initial operational concepts  

NASA Astrophysics Data System (ADS)

The feasibility of single-stage-to-orbit (SSTO) is being demonstrated by a three-stage experimental vehicle test-flight scheme which will begin with the DC-X and DC-X2 suborbital vehicles and culminate with the DC-Y orbital launcher. While the DC-X would use comparatively heavy off-the-shelf hardware to explore operations-related issues, the DC-X2 would demonstrate lightweight structural technologies. The DC-Y would then test the thermal protection system required for reentry.

Dornheim, Michael A.

1993-10-01

364

Improvement of In-Flight Alumina Spheroidization Process Using a Small Power Argon DC-RF Hybrid Plasma Flow System by Helium Mixture  

NASA Astrophysics Data System (ADS)

For the further improvement of in-flight alumina spheroidization process with a low-power direct-current radiofrequency (DC-RF) hybrid plasma flow system, the effect of a small amount of helium gas mixture in argon main gas and also the effect of increasing DC nozzle diameter on powder spheroidization ratio have been experimentally clarified with correlating helium gas mixture percentage, plasma enthalpy, powder in-flight velocity, and temperature. The alumina spheroidization ratio increases by helium gas mixture as a result of enhancement of plasma enthalpy. The highest spheroidization ratio is obtained by 4% mixture of helium in central gas with enlarging nozzle diameter from 3 to 4 mm, even under the constant low input electric power given to a DC-RF hybrid plasma flow system.

Takana, Hidemasa; Jang, Juyong; Igawa, Junji; Nakajima, Tomoki; Solonenko, Oleg P.; Nishiyama, Hideya

2011-03-01

365

Vibrating Wire Loop and the Bohr Model  

Microsoft Academic Search

PASCO scientific1 has designed a vibration apparatus that includes a mechanical driver used to excite vibrations in various systems. One of these is a circular wire loop, which PASCO suggests can be used as a visual representation of the Bohr model of the hydrogen atom. In this paper we investigate the similarity between the wire loop and the Bohr atom.

Danning Bloom; Dan W. Bloom

2003-01-01

366

Power Network impedance effects on noise emission of DC-DC converters  

NASA Astrophysics Data System (ADS)

The characterization of electromagnetic noise emissions of DC-DC converters is a critical issue that has been analyzed during the desing phase of CMS tracker upgrade. Previous simulation studies showed important variations in the level of conducted emissions when DC-DC converters are loaded/driven by different impedances and power network topologies. Several tests have been performed on real DC-DC converters to validate the Pspice model and simulation results. This paper presents these test results. Conducted noise emissions at the input and at the output terminals of DC-DC converters has been measured for different types of power and FEE impedances. Special attention has been paid to influence on the common-mode emissions by the carbon fiber material used to build the mechanical structure of the central detector. These study results show important recommendations and criteria to be applied in order to decrease the system noise level when integrating the DC-DC.

Esteban, M. C.; Arteche, F.; Iglesias, M.; Gimeno, A.; Arcega, F. J.; Johnson, M.; Cooper, W. E.

2012-01-01

367

Infrared imaging systems technology; Proceedings of the Seminar, Washington, DC, April 10, 11, 1980  

Microsoft Academic Search

Among the topics discussed in the field of infrared imaging systems are: spectral imaging with the Michelson interferometer, thermal IR imaging with a CCD array, pushbroom and whiskbroom scanners, and staring mosaic sensor system design. Also covered are optimum-performance focal plane array design, dual active\\/passive IR imaging systems, reflective IR imager optics, precision diamond machining, and prototype designs for a

J. Zimmerman; W. L. Wolfe

1980-01-01

368

EC417 --Electric Energy, Adapting to Renewable Resources Brief History of Power Systems (the great AC-DC battle)  

E-print Network

EC417 -- Electric Energy, Adapting to Renewable Resources Fall 2014 Topics: · Brief History (generation, transmission, distribution -- electric motors and other loads) · Power Plants with emphasis Power and Power Factor calculations · Transformers · Introduction to Power Electronics and AC/DC and DC

369

Reprint of Performance analysis of a model-sized superconducting DC transmission system based VSC-HVDC transmission technologies using RTDS  

NASA Astrophysics Data System (ADS)

The combination of a high temperature superconducting DC power cable and a voltage source converter based HVDC (VSC-HVDC) creates a new option for transmitting power with multiple collection and distribution points for long distance and bulk power transmissions. It offers some greater advantages compared with HVAC or conventional HVDC transmission systems, and it is well suited for the grid integration of renewable energy sources in existing distribution or transmission systems. For this reason, a superconducting DC transmission system based HVDC transmission technologies is planned to be set up in the Jeju power system, Korea. Before applying this system to a real power system on Jeju Island, system analysis should be performed through a real time test. In this paper, a model-sized superconducting VSC-HVDC system, which consists of a small model-sized VSC-HVDC connected to a 2 m YBCO HTS DC model cable, is implemented. The authors have performed the real-time simulation method that incorporates the model-sized superconducting VSC-HVDC system into the simulated Jeju power system using Real Time Digital Simulator (RTDS). The performance analysis of the superconducting VSC-HVDC systems has been verified by the proposed test platform and the results were discussed in detail.

Dinh, Minh-Chau; Ju, Chang-Hyeon; Kim, Sung-Kyu; Kim, Jin-Geun; Park, Minwon; Yu, In-Keun

2013-01-01

370

WIRE, SOFIA and SIRTF  

NASA Technical Reports Server (NTRS)

WIRE, SOFIA and SIRTF are three planned NASA missions for infrared astronomy. Each will make significant contributions to the study of exo-zodiacal dust, planetary debris disks, and/or the zodiacal material within our own solar system. These missions and their measurement and scientific capabilities are synopsized. The principal contribution of these missions to this field of study will be to establish and strengthen its intellectual foundations rather than to pinpoint specific targets for planetary searches. This is consistent with their relatively near-term availability. Moreover, this intellectual understanding can assure that subsequent missions approach this subject from a sound scientific perspective which will yield valuable results independent of the success of a particular planet finding strategy. Each of these missions - most urgently WIRE with its Fall, 1998 launch date - would make good use of a list of candidate target stars for exo-zodiacal/planet-finding studies. The preparation of such a list was one of the recommendations of the exo-zodiacal workshop.

Werner, Michael

1998-01-01

371

Influence of the current control loops of DC arc furnaces on voltage fluctuations and harmonics in the HV power supply system  

Microsoft Academic Search

It is necessary, to an increasing extent, to take controllers and control loops into consideration in mathematical modelling and simulations for power quality studies. DC arc furnaces belong to those electric loads which network behaviour is essentially influenced by control processes. Rated at more than 100 MVA, these furnaces cause voltage fluctuations and harmonics in the HV power system. Based

D. Stade; H. Schau; St. Prinz

2000-01-01

372

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

373

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...

374

Composite ceramic superconducting wires for electric motor applications  

NASA Astrophysics Data System (ADS)

Several types of HTSC wire have been produced and two types of HTSC motors are being built. Hundreds of meters of Ag- clad wire were fabricated from YBa2Cu3O(7-x) (Y-123) and Bi2Ca2Sr2Cu3O10 (BiSCCO). The dc homopolar motor coils are not yet completed, but multiple turns of wire have been wound on the coil bobbins to characterize the superconducting properties of coiled wire. Multifilamentary conductors were fabricated as cables and coils. The sintered polycrystalline wire has self-field critical current densities (Jc) as high as 2800 A/sq cm, but the Jc falls rapidly with magnetic field. To improve Jc, sintered YBCO wire is melt textured with a continuous process which has produced textures wire up to 0.5 meters long with 77K transport Jc above 11, 770 A/sq cm2 in self field and 2100 A/sq cm2 at 1 telsa. The Emerson Electric dc homopolar HTSC motor has been fabricated and run with conventional copper coils. A novel class of potential very powerful superconducting motors have been designed to use trapped flux in melt textures Y-123 as magnet replicas in an new type of permanent magnet motor. The stator element and part of the rotor of the first prototype machine exist, and the HTSC magnet replica segments are being fabricated.

Halloran, John W.

1990-07-01

375

dcOvercoming Communications Challenges in Software for Monitoring and Controlling Power Systems  

Microsoft Academic Search

The restructuring of the electric power grid has created new control and monitoring requirements for which classical technologies may be inadequate. The most obvious way of building such systems, using TCP connections to link monitoring systems with data sources, gives poor scalability and exhibits instability precisely when information is most urgently required. Astrolabe, Bimodal Multicast, and Gravitational Gossip, technologies of

Kenneth P. Birman; Jie Chen; ENNETH M. HOPKINSON; ROBERT J. THOMAS; JAMES S. THORP; Robbert van Renesse; Werner Vogels

2005-01-01

376

Study of overhead ground-wire shunting rates during grounding failure, for 500 kV substation grounding system design  

Microsoft Academic Search

Ensuring the prescribed grounding resistance for 500 kV substations has become difficult due to various factors including increased short-circuit capacity, reduction of substation area, and construction of substations in mountainous locations, making it necessary to drive electrodes deep into the ground at high cost. To find a solution to this problem, we reviewed overhead ground-wire shunting rates during grounding failure,

H. Makino; H. Itakura

1999-01-01

377

Steady-state analysis of a faulted three-phase four-wire system supplying induction motors with neutrals connected and other single-phase line-to-neutral loads  

NASA Technical Reports Server (NTRS)

Four wire Wye connected ac power systems exhibit peculiar steady state fault characteristics when the fourth wire of three phase induction motors is connected. The loss of one phase of power source due to a series or shunt fault results in currents higher than anticipated on the remaining two phases. A theoretical approach to compute the fault currents and voltages is developed. A FORTRAN program is included in the appendix.

Wood, M. E.

1980-01-01

378

Cooling test of the 200 m superconducting DC transmission power cable system at Chubu University  

NASA Astrophysics Data System (ADS)

A second cooling test of CASER2, the 200 m class superconducting direct current power transmission system at Chubu University, was performed from August to October 2010. During this time, the system was cooled down and the liquid nitrogen which cooled the superconducting power cable was circulated in the cryogenic pipe of CASER2. The heat leak of the cryogenic pipe was measured and the values of about 300 W was obtained. This result will be used further improvements of CASER2.

Watanabe, H.; Sugino, M.; Sun, J.; Ivanov, Y.; Hamabe, M.; Kawahara, T.; Yamaguchi, S.

2011-11-01

379

High-voltage (270 V) dc power-generating system for fighter aircraft  

NASA Technical Reports Server (NTRS)

The advantages of using high voltage, direct current advanced power generating systems in fighter aircraft are discussed. Weight reduction is achieved. Efficiency is increased 85 to 90 percent by eliminating the constant speed drive. Power interruptions are eliminated. There are no speed restrictions and no powerline constraints. Personal safety is increased by eliminating the hold on frequency, present in ac systems, which causes muscle contractions.

Mcginley, K. M.

1983-01-01

380

Reliability Assessment of Fault-Tolerant Dc-Dc Converters for Photovoltaic Applications  

E-print Network

Reliability Assessment of Fault-Tolerant Dc-Dc Converters for Photovoltaic Applications Sairaj V in photovoltaic energy processing applications is presented. The proposed approach acknowledges the influence through several case studies. Index Terms-- Markov reliability modeling, photovoltaic systems, power

Liberzon, Daniel

381

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.

382

Development of contact-wire\\/battery hybrid LRV  

Microsoft Academic Search

Contact-wire\\/onboard battery hybrid railway electric vehicles run on a hybrid power source that enables energy to be fed from contact wires and \\/or onboard batteries. We developed a contact-wire\\/battery hybrid LRV (Light Rail Vehicle) and had it manufactured. This paper concerns the hybrid source technology for the contact-wire\\/battery hybrid system, and on the running results with onboard rechargeable lithium ion

Masamichi OGASA; Yoshiaki TAGUCHI

2010-01-01

383

EHD surface waves of diesel oil thin films generated by wire-plate barrier discharges  

Microsoft Academic Search

An experimental investigation has been conducted to study electrohydrodynamically (EHD) induced surface wave phenomena on the surface of dielectric diesel oil thin films under wire-plate barrier discharges. Experimental arrangements used in the present investigation consisted of a corona wire, air gaps, thin oil film, mylor sheet and conducting transparent sheet placed on the lucite plate. Positive dc (on\\/off) high voltage

Jen-Shih Chang; K. Urashima; J. Cho; G. Artana; G. Touchard

1997-01-01

384

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

385

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

386

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

387

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

388

Lingual straight wire method.  

PubMed

The mushroom arch-wire is mainly used in lingual orthodontic treatment but the complicated wire bending it requires affects both the treatment results and the time spent at the chair. The author proposes a new lingual straight wire method (LSW) in order to facilitate arch coordination and simplify the mechanics. The attention paid to the set-up model and bracket positioning and bonding plus the use of the new LSW method will also improve patient comfort. PMID:20303920

Takemoto, Kyoto; Scuzzo, Giuseppe; Lombardo, L U C A; Takemoto, Y U I

2009-12-01

389

Comparison of the Initial Orthodontic Force Systems Produced by a New Lingual Bracket System and a Straight-Wire Appliance  

Microsoft Academic Search

Background and Aim: Over the last few years, lingual appliances have become an established orthodontic treatment technique. Many studies have concentrated on various esthetic aspects, on laboratory and clinical procedures, and on patient comfort and compliance. The orthodontic force systems of these appliances, however, have not yet been investigated. The aim of this study was thus to determine the forces

Lars-Michael Fuck; Dirk Wiechmann; Dieter Drescher

2005-01-01

390

Wire-free fixation of jaw fractures.  

PubMed

Stainless steel wire is often used in the management of jaw fractures to provide intraoperative or postoperative intermaxillary fixation (IMF). Wiring of the jaws is time-consuming, a second procedure is needed to remove it, and needlestick injuries occur during placement. We report on 151 consecutive patients who had wire-free fixation of jaw fractures, and outline the value of a system of plastic anchorage points applied to individual teeth in both jaws that allows for wire-free IMF when they are linked by elastics (Rapid IMF, Synthes, PA, USA). A total of 150 successive patients had wire-free fixation of 146 mandibular and 5 maxillary fractures. Ninety-eight were hand-held in occlusion, and 52 were treated using Rapid IMF. There were few complications. PMID:19608310

Cousin, G C S

2009-10-01

391

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

392

Balancing control method by dispersed generators based on H ? control theory in DC power feeding system  

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 ultra capacitor energy storage system is used for compensating the instantaneous power imbalance. However, use of a large capacity ultra capacitor energy

Kenichi Tanaka; Tomonori Goya; Tomonobu Senjyu; Atsushi Yona; Naomitsu Urasaki; Toshihisa Funabashi; Chul-Hwan Kim

2011-01-01

393

Energy management by coordination control of DC bus voltage in PV hydrogen system  

Microsoft Academic Search

This study aims to the modeling and simulation of a production hybrid source. This source comprises a photovoltaic generator (PV), an alkaline water electrolyzer (ELZ), a storage gas tank, a proton exchange membrane fuel cell (PEMFC), a Super-capacitor bank (SC) and power conditioning unit (PCU) to give different system topologies. Electricity is generated by a PV generator to meet the

Rihab Jallouli; Lotfi Krichen

2012-01-01

394

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

395

Development of a DC-DC conversion powering scheme for the CMS Phase-1 pixel upgrade  

NASA Astrophysics Data System (ADS)

A novel powering scheme based on the DC-DC conversion technique will be exploited to power the CMS Phase-1 pixel detector. DC-DC buck converters for the CMS pixel project have been developed, based on the AMIS5 ASIC designed by CERN. The powering system of the Phase-1 pixel detector is described and the performance of the converter prototypes is detailed, including power efficiency, stability of the output voltage, shielding, and thermal management. Results from a test of the magnetic field tolerance of the DC-DC converters are reported. System tests with pixel modules using many components of the future pixel barrel system are summarized. Finally first impressions from a pre-series of 200 DC-DC converters are presented.

Feld, L.; Fimmers, C.; Karpinski, W.; Klein, K.; Lipinski, M.; Preuten, M.; Rauch, M.; Rittich, D.; Sammet, J.; Wlochal, M.

2014-01-01

396

Lubrication Basics for Wire Ropes  

Microsoft Academic Search

Wire rope forms an important part of many machines and structures. It is comprised of continuous wire strands wound around a central core. There are many kinds of wire rope designed for different applications. Most of them are steel wires made into strands wound with each other. The core can be made of steel, rope or even plastics. Wire ropes

Jeffrey E. Turner; Christopher Barnes

397

Failure of crane wire rope  

Microsoft Academic Search

A failure analysis of a broken multi strand wire rope from a crane was performed. The fracture of the steel wires in the wire rope showed characteristics of fatigue. On the wire surface were observed decarburised cracks which act as initiation sites for fatigue crack propagation during the application of the wire rope. The main reasons for the failure of

M. Torkar; B. Arzenek

2002-01-01

398

New Materials for Bonding Wire  

Microsoft Academic Search

In this paper, Insulated wire for Fine pad pitch bonding and 3D PKG technology, Cu wire and Au-Ag wire for cost reduction, and Ag wire in response to bond pad metallization change are reviewed from technology aspect. With only few tens of nanometers thick coating layer, insulated wire forms stable free air ball with good 1 st bond bondability. As

Jeong Tak Moon; June Sub Hwang; Jong Su Cho; Seong Hyoun Kim

399

DC/AC Student Guide: Amp Meter System and Design Testing Lab  

NSDL National Science Digital Library

This lab activity brings together all the principles and laws of parallel circuits. The primary purpose of the lab is to design, construct, and test a multi-range ammeter. In the process of doing this lab activity, the principles of Ohm's Law, Watt's Law, Kirchhoff's Parallel Circuit Laws, and the basic operation of an analog and a digital meter movement will be reviewed and emphasized. The interrelationships between various parts will be highlighted and a basic amperage measurement system will be constructed and tested.

Brixen, Roy

2014-08-14

400

AC/DC Power Systems with Applications in Future Human Habitat on Lunar and Mars Bases  

NASA Astrophysics Data System (ADS)

As NASA readies itself for new space exploration initiatives starting with a human return to the Moon by the year 2020 eventually leading to human exploration of Mars, the requirements for a safe, efficient and comprehensive power system to support the exploration missions as well human habitat will become important issues to consider. Certain issues dealing with electric power generation and distribution on board Mars-bound vehicles and those on Lunar and Martian surfaces are described. The requirements for lightweight power generation dictates the use of a high frequency ac machine. Preliminary results of investigating the design of a permanent magnet synchronous machine is presented.

Chowdhury, Badrul H.; Hossain, Sabbir A.; Lawrence, James T.; Barave, Sushant

2006-01-01

401

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

402

Digital Control Technologies for Modular DC-DC Converters  

NASA Technical Reports Server (NTRS)

Recent trends in aerospace Power Management and Distribution (PMAD) systems focus on using commercial off-the-shelf (COTS) components as standard building blocks. This move to more modular designs has been driven by a desire to reduce costs and development times, but is also due to the impressive power density and efficiency numbers achieved by today's commercial DC-DC converters. However, the PMAD designer quickly learns of the hidden "costs" of using COTS converters. The most significant cost is the required addition of external input filters to meet strict electromagnetic interference (MIAMI) requirements for space systems. In fact, the high power density numbers achieved by the commercial manufacturers are greatly due to the lack of necessary input filters included in the COTS module. The NASA Glenn Research Center is currently pursuing a digital control technology that addresses this problem with modular DC-DC converters. This paper presents the digital control technologies that have been developed to greatly reduce the input filter requirements for paralleled, modular DC-DC converters. Initial test result show that the input filter's inductor size was reduced by 75 percent, and the capacitor size was reduced by 94 percent while maintaining the same power quality specifications.

Button, Robert M.; Kascak, Peter E.; Lebron-Velilla, Ramon

2002-01-01

403

The WASP-binding protein WIRE has a role in the regulation of the actin filament system downstream of the platelet-derived growth factor receptor.  

PubMed

Activation of growth factor receptors, such as platelet-derived growth factor (PDGF) receptors, has a major impact on the motile behavior of vertebrate cells. The WASP family of proteins has been recognized as important regulators of actin polymerization via the activation of the Arp2/3 complex. The activity of the WASP proteins has, in turn, been shown to be governed by a number of associated proteins, including the WASP interacting protein (WIP). This report presents a novel WIP-like protein, WIRE (for WIP-related). WIRE was shown to bind to the WH1 domain of WASP and N-WASP. WIRE was localized to actin filaments in transiently transfected PAE/PDGFRbeta cells, and in cells simultaneously expressing WIRE and WASP, WIRE relocalized WASP to actin filaments, a relocalization that required direct interaction between the two proteins. In addition, WIRE was able to bind the PDGF receptor substrate Nckbeta. PDGF treatment of cells ectopically expressing WIRE resulted in formation of peripheral protrusions composed of filopodia and lamellipodia-like structures. In cells expressing both WIRE and WASP, PDGF treatment induced a translocation of WASP to the cell margin, an effect that required the presence of WIRE. Taken together, the data presented indicate that WIRE has a role in the WASP-mediated organization of the actin cytoskeleton and that WIRE is a potential link between the activated PDGF receptor and the actin polymerization machinery. PMID:12213210

Aspenstrm, Pontus

2002-09-10

404

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

405

NASA requirements and applications environments for electrical power wiring  

NASA Technical Reports Server (NTRS)

Serious problems can occur from insulation failures in the wiring harnesses of aerospace vehicles. In most recorded incidents, the failures have been identified to be the result of arc tracking, the propagation of an arc along wiring bundles through degradation of insulation. Propagation of the arc can lead to the loss of the entire wiring harness and the functions which it supports. While an extensive database of testing for arc track resistant wire insulations has been developed for aircraft applications, the counterpart requirements for spacecraft are very limited. The electrical, thermal, mechanical, chemical, and operational requirements for specification and testing of candidate wiring systems for spacecraft applications is presented.

Stavnes, Mark W.; Hammoud, Ahmad N.

1992-01-01

406

Excitation Spectra of 1D Quantum Wires  

NASA Astrophysics Data System (ADS)

In this talk two different aspects of the excitation spectra of one dimensional (1D) semiconductor quantum wires will be discussed: (1) The nature of collective electronic excitations in 1D quantum wires; and (2) the band gap renormalization and excitonic effects in 1D quantum wires. In the first part, extensive theoretical results using the Bethe ansatz technique, the Lanczos' method, and the diagrammatic many-body theory will be presented for the spectral weight and the mode dispersion of the low-lying elementary electronic excitation spectra in 1D quantum wires with comparison to Raman Scattering experiments in GaAs quantum wires. Based on our detailed analytical and numerical results we conclude that the experimental observations are consistent with the existence of the collective charge density excitation mode, the collective spin density excitation mode, and a (low spectral weight) finite wave vector electron-hole single particle excitation mode (which arises from the finite curvature of the electron energy dispersion in the system). There is no evidence for a singlet spin density excitation mode in our calculations. In the second part, numerical solutions of the Bethe-Salpeter equation for interband excitonic transitions in 1D quantum wires will be presented. An approximate cancellation between self-energy and vertex correction effects is obtained in our calculations, providing an explaination for the experimental observation of an unshifted excitonic peak in highly excited 1D quantum wire lasers.

Wang, Daw-Wei

1998-03-01

407

Distribution of wire deformation within strands of wire ropes  

Microsoft Academic Search

Using ANSYS software, we developed a modeling program for several kinds of wire ropes with metal cores and built a geometric model for the 619 IWS wire rope. Through proper grid partitioning, a finite element model for calculating the deformation of wire rope was obtained. Completely constraining one end of the wire rope and applying an axial force to the

Jun MA; Shi-rong GE; De-kun ZHANG

2008-01-01

408

Qualitative comparison of calculated turbulence responses with wind-tunnel measurements for a DC-10 derivative wing with an active control system  

NASA Technical Reports Server (NTRS)

Comparisons are presented analytically predicted and experimental turbulence responses of a wind tunnel model of a DC-10 derivative wing equipped with an active control system. The active control system was designed for the purpose of flutter suppression, but it had additional benefit of alleviating gust loads (wing bending moment) by about 25%. Comparisions of various wing responses are presented for variations in active control system parameters and tunnel speed. The analytical turbulence responses were obtained using DYLOFLEX, a computer program for dynamic loads analyses of flexible airplanes with active controls. In general, the analytical predictions agreed reasonably well with the experimental data.

Perry, B., III

1981-01-01

409

Quantitative study of macroscopic quantum tunneling in a dc SQUID: A system with two degrees of freedom  

E-print Network

measurements at T=4.2 K, we are able to make quantitative comparison to the theories from 8 mK to 4.2 K. The excellent agreement between the data and the MQT theory demonstrates that tunneling from the zero-voltage state of the dc SQUID is well described...

Li, Shaoxiong; Yu, Yang; Zhang, Y.; Qiu, W.; Han, Siyuan; Wang, Z.

2002-08-01

410

Dilution control in single-wire stainless steel submerged arc cladding  

SciTech Connect

An experimental study of the effects of bead-to-bead stepover, wire size, wire feed speed, voltage, flux chromium content, and polarity on dilution and ferrite in single-wire submerged arc cladding of ER309L on mild steel plate is described. Low dilution was found to be promoted by reduced stepover, reduced wire feed speed, and DC electrode negative polarity. Use of a high-chromium flux can broaden the tolerance for dilution, providing an austenitic deposit free of martensite, and containing at least 4 FN for assurance of freedom from hot cracking over a broader range of dilutions.

Kotecki, D.J. [Lincoln Electric Co., Cleveland, OH (United States)

1996-02-01

411

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

E-print Network

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

Egerstedt, Magnus

412

Advancement of In-Flight Alumina Powder Spheroidization Process with Water Droplet Injection Using a Small Power DC-RF Hybrid Plasma Flow System  

NASA Astrophysics Data System (ADS)

The correlation between plasma thermofluid characteristics and alumina powder spheroidization processes with water droplet injection using a small power DC-RF hybrid plasma flow system was experimentally clarified. Micro-sized water droplets with a low water flow rate were injected into the tail of thermal plasma flow so as not to disturb the plasma flow directly. Injected water droplets were vaporized in the thermal plasma flow and were transported upstream in the plasma flow to the torch by the backflow. After dissociation of water, the production of hydrogen was detected by the optical emission spectroscopy in the downstream RF plasma flow. The emission area of the DC plasma jet expanded and elongated in the vicinity of the RF coils. Additionally, the emission area of RF plasma flow enlarged and was visible as red emission in the downstream RF plasma flow in the vicinity below the RF coils due to hydrogen production. Therefore, the plasma flow mixed with produced hydrogen increased the plasma enthalpy and the highest spheroidization rate of 97% was obtained at a water flow rate of 15 Sm l/min and an atomizing gas flow rate of 8 S l/min using a small power DC-RF hybrid plasma flow system.

Jang, Juyong; Takana, Hidemasa; Park, Sangkyu; Nishiyama, Hideya

2012-09-01

413

Far-infrared spectroscopy of one- and zero-dimensional electronic systems  

Microsoft Academic Search

We review the far infrared (FIR) response of one- and zero-dimensional electronic systems (0DES and 1DES), quantum wires and quantum dots, respectively, which have been realized by ultrafine mesa etching of modulation-doped AlGaAs\\/GaAs heterostructures. From dc magnetotransport measurements on quantum wires the formation of 1D subbands with typical energy separations of 1 to 3 meV was found in electron channels

T. Demel; D. Heitmann; P. Grambow; K. Ploog

1991-01-01

414

Effect of relative humidity on electron distribution and ozone production by DC coronas in air  

Microsoft Academic Search

The effect of relative humidity on the electron distribution and the ozone production in the direct current (dc) corona discharge from a thin wire is evaluated with a numerical model. The model is based on the prior models of ozone production by dc coronas in dry air, with modifications to incorporate the effect of water vapor on the corona plasma

Junhong Chen; Pengxiang Wang

2005-01-01

415

Effect of relative humidity on electron distribution and ozone production by DC coronas in air  

Microsoft Academic Search

Summary form only given. A numerical model of electron distribution and ozone production in clean and humid air by DC corona discharges from a thin wire is presented. The model is based on the prior models of ozone production by DC coronas in dry air, with modifications to incorporate the effect of water vapor on the electrical characteristics and the

Junhong Chen; Pengxiang Wang

2004-01-01

416

Dispersion interactions between semiconducting wires  

NASA Astrophysics Data System (ADS)

The dispersion energy between extended molecular chains (or equivalently infinite wires) with nonzero band gaps is generally assumed to be expressible as a pair-wise sum of atom-atom terms which decay as R-6 . Using a model system of two parallel wires with a variable band gap, we show that this is not the case. The dispersion interaction scales as z-5 for large interwire separations z , as expected for an insulator, but as the band gap decreases the interaction is greatly enhanced; while at shorter (but nonoverlapping) separations it approaches a power-law scaling given by z-2 , i.e., the dispersion interaction expected between metallic wires. We demonstrate that these effects can be understood from the increasing length scale of the plasmon modes (charge fluctuations), and their increasing contribution to the molecular dipole polarizability and the dispersion interaction, as the band gaps are reduced. This result calls into question methods which invoke locality assumptions in deriving dispersion interactions between extended small-gap systems.

Misquitta, Alston J.; Spencer, James; Stone, Anthony J.; Alavi, Ali

2010-08-01

417

Model of Ozone Production in the DC Corona Discharge  

Microsoft Academic Search

A comprehensive numerical model of ozone production in clean, dry air by DC corona discharges is presented. This model combines a first-principle corona plasma model with a chemistry and 2-D transport model to obtain the distributions of ozone and other gaseous products in the neighborhood of a corona discharge wire. Electron number density distribution is obtained by solving the continuity

Junhong Chen; Jane Davidson

2002-01-01

418

Burnout protection of a hot-wire anemometer  

Microsoft Academic Search

A burnout protection circuit which will prevent hot-wire overloading is described. The transient response of a hot-wire system to power loading is examined. Two methods for preventing the overloading of the hot-wire system are: (1) to start the positive power earlier than the negative power or (2) to slowly start the power transistor after the bipolar powers are imposed on

S. Takagi

1990-01-01

419

Novel Gapped Quantum Wire  

NASA Astrophysics Data System (ADS)

High quality state of the art quantum wires (QWRs) can be fabricated by the novel cleaved edge overgrowth technique, proposed by (Pfeiffer et al., 1990). Transverse quantization in these QWRs leads to a succession of nested energy bands. With the lowest two successive energy levels occupied, gapped phases are possible including, e.g, an intersubband charge density wave (ICDW) and a Cooper phase with strong superconducting fluctuations (Starykh et al., 2000). Due to the possibility of density reorganization, in which it becomes favorable for the two lowest subbands to match their densities, the ICDW is usually the most likely state. Recently, by exploiting the valley degeneracy in AlAs, a single QWR has been fabricated with two degenerate nonoverlapping bands separated in k space by half an Umklapp vector (Moser et al. 2004). For low densities this structure is able to access a multiple subband regime that is not subject to the density reorganizing ICDW, leaving the Cooper phase to flourish. Using Abelian bosonization, we explore the relevant interaction terms for this system, including Umklapp assisted Cooper scattering, and discuss the phase diagram.

Datta, Trinanjan

2005-03-01

420

Novel Gapped Quantum Wire  

NASA Astrophysics Data System (ADS)

High quality state of the art quantum wires (QWRs) can be fabricated by the novel Cleaved Edge Overgrowth (CEO) technique, proposed by (Pfeiffer et al, 1990). Transverse quantization in these QWRs leads to a succession of nested energy bands. With the lowest two successive energy levels occupied, gapped phases are possible including, e.g., an intersubband charge density wave (ICDW) and a Cooper phase with strong superconducting fluctuations (Starykh et al, 2000). Due to the possibility of density reorganization, in which it becomes favorable for the two lowest subbands to match their densities, the ICDW is usually the most likely state. Recently, by exploiting the valley degeneracy in AlAs, a single QWR has been fabricated with two degenerate nonoverlapping bands separated in k space by half an Umklapp vector (Moser et al 2004). For low densities the structure is able to access a multiple subband regime that is not subject to the density reorganizing ICDW, leaving a Cooper phase to flourish. Using Abelian bosonization, we explore the relevant interaction terms for this system, including Umklapp assisted Cooper scattering and discuss the phase diagram.

Datta, Trinanjan

2005-04-01

421

Needleless electrospinning with twisted wire spinneret.  

PubMed

A needleless electrospinning setup named 'Needleless Twisted Wire Electrospinning' was developed. The polymer solution is electrospun from the surface of a twisted wire set to a high voltage and collected on a cylindrical collector around the wire. Multiple Taylor cones are simultaneously self-formed on the downward flowing solution. The system is robust and simple with no moving parts aside from the syringe pump used to transport the solution to the top of the wire. The structure and process parameters of the setup and the results on the preparation of polyvinyl pyrrolidone (PVP), hydroxyapatite (HA) and bioglass fibers with the setup are presented. PVP fiber sheets with areas of 40נ120 cm(2) and masses up to 1.15 g were prepared. High production rates of 5.23 g h(-1) and 1.40 g h(-1) were achieved for PVP and HA respectively. The major limiting factor of the setup is drying of the polymer solution on the wire during the electrospinning process which will eventually force to interrupt the process for cleaning of the wire. Possible solutions to this problem and other ways to develop the setup are discussed. The presented system provides a simple way to increase the production rate and area of fiber sheet as compared with the conventional needle electrospinning. PMID:25513842

Holopainen, Jani; Penttinen, Toni; Santala, Eero; Ritala, Mikko

2015-01-16

422

Needleless electrospinning with twisted wire spinneret  

NASA Astrophysics Data System (ADS)

A needleless electrospinning setup named Needleless Twisted Wire Electrospinning was developed. The polymer solution is electrospun from the surface of a twisted wire set to a high voltage and collected on a cylindrical collector around the wire. Multiple Taylor cones are simultaneously self-formed on the downward flowing solution. The system is robust and simple with no moving parts aside from the syringe pump used to transport the solution to the top of the wire. The structure and process parameters of the setup and the results on the preparation of polyvinyl pyrrolidone (PVP), hydroxyapatite (HA) and bioglass fibers with the setup are presented. PVP fiber sheets with areas of 40 120 cm2 and masses up to 1.15 g were prepared. High production rates of 5.23 g h?1 and 1.40 g h?1 were achieved for PVP and HA respectively. The major limiting factor of the setup is drying of the polymer solution on the wire during the electrospinning process which will eventually force to interrupt the process for cleaning of the wire. Possible solutions to this problem and other ways to develop the setup are discussed. The presented system provides a simple way to increase the production rate and area of fiber sheet as compared with the conventional needle electrospinning.

Holopainen, Jani; Penttinen, Toni; Santala, Eero; Ritala, Mikko

2015-01-01

423

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2012 CFR

...Resources 1 2012-07-01 2012-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 77.1802 Insulation of trolley wires, trolley feeder wires and bare signal...

2012-07-01

424

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2012 CFR

...Resources 1 2012-07-01 2012-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 75.1003 Insulation of trolley wires, trolley feeder wires and bare signal...

2012-07-01

425

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2011 CFR

...Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 77.1802 Insulation of trolley wires, trolley feeder wires and bare signal...

2011-07-01

426

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2013 CFR

...Resources 1 2013-07-01 2013-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 77.1802 Insulation of trolley wires, trolley feeder wires and bare signal...

2013-07-01

427

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2014 CFR

...Resources 1 2014-07-01 2014-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 77.1802 Insulation of trolley wires, trolley feeder wires and bare signal...

2014-07-01

428

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2013 CFR

...Resources 1 2013-07-01 2013-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 75.1003 Insulation of trolley wires, trolley feeder wires and bare signal...

2013-07-01

429

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2014 CFR

...Resources 1 2014-07-01 2014-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 75.1003 Insulation of trolley wires, trolley feeder wires and bare signal...

2014-07-01

430

30 CFR 77.1802 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2010 CFR

...Resources 1 2010-07-01 2010-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 77.1802 Insulation of trolley wires, trolley feeder wires and bare signal...

2010-07-01

431

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2010 CFR

...Resources 1 2010-07-01 2010-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 75.1003 Insulation of trolley wires, trolley feeder wires and bare signal...

2010-07-01

432

30 CFR 75.1003 - Insulation of trolley wires, trolley feeder wires and bare signal wires; guarding of trolley...  

Code of Federal Regulations, 2011 CFR

...Resources 1 2011-07-01 2011-07-01 false Insulation of trolley wires, trolley feeder wires and bare signal wires...MINES Trolley Wires and Trolley Feeder Wires 75.1003 Insulation of trolley wires, trolley feeder wires and bare signal...

2011-07-01

433

Pin Wire Coating Trip Report  

SciTech Connect

A meeting to discuss the current pin wire coating problems was held at the Reynolds plant in Los Angeles on 2MAR04. The attendance list for Reynolds personnel is attached. there was an initial presentation which gave a brief history and the current status of pin wire coating at Reynolds. There was a presentation by Lori Primus on the requirements and issues for the coating. There was a presentation by Jim Smith of LANL on the chemistry and to some extent process development done to date. There was a long session covering what steps should be taken in the short term and, to a lesser extent, the long term. The coating currently being used is a blend of two polymers, polyethersulfone and polyparabanic acid (PPA) and some TiO2 filler. This system was accepted and put into production when the pin wire coating was outsourced to another company in 1974. When that company no longer was interested, the wire coating was brought in-house to Reynolds. At that time polyparabanic acid was actually a commercial product available from Exxon under the trade name Tradlon. However, it appears that the material used at Reynolds was synthesized locally. Also, it appears that a single large batch was synthesized in that time period and used up to 1997 when the supply ran out. The reason for the inclusion of TiO2 is not known although it does act as a rheological thickener. However, a more controlled thickening can be obtained with materials such as fumed silica. This material would have less likelihood of causing point imperfections in the coatings. Also, the mixing technique being used for all stages of the process is a relatively low shear ball mill process and the author recommends a high shear process such as a three roll paint mill, at least for the final mixing. Since solvent is added to the powder at Reynolds, it may be that they need to have the paint mill there.

Spellman, G P

2004-03-18

434

Development of lightning-resistant overhead ground wire  

SciTech Connect

Overhead ground wires (GW) are vulnerable to strand breakage due to lightning strikes. With the wider application in recent years of Composite Fiber Optic Ground Wire (OPGW), it becomes more important to protect GW from such damage. In this paper, the authors present the results of various investigations made in developing lightning-resistant GW/OPGW. Investigations included field experiments using rocket-triggered lightning, studies on materials and designs to improve lightning characteristics and various evaluation tests, such as DC arc tests, of several prototypes. As a result, the authors have developed excellent lightning-resistant GW/OPGW applicable for conventional transmission lines.

Yokoya, Munehisa; Katsuragi, Yukio (Chubu Electric Power Co., Inc., Nagoya (Japan)); Goda, Yutaka (Central Research Inst. of the Electric Power Industry, Yokosuka (Japan)); Nagata, Yutaka; Asano, Yuji (Fujikura Ltd., Tokyo (Japan))

1994-07-01

435

Understanding Climate Policy Data Needs. NASA Carbon Monitoring System Briefing: Characterizing Flux Uncertainty, Washington D.C., 11 January 2012  

NASA Technical Reports Server (NTRS)

Climate policy in the United States is currently guided by public-private partnerships and actions at the local and state levels. This mitigation strategy is made up of programs that focus on energy efficiency, renewable energy, agricultural practices and implementation of technologies to reduce greenhouse gases. How will policy makers know if these strategies are working, particularly at the scales at which they are being implemented? The NASA Carbon Monitoring System (CMS) will provide information on carbon dioxide fluxes derived from observations of earth's land, ocean and atmosphere used in state of the art models describing their interactions. This new modeling system could be used to assess the impact of specific policy interventions on CO2 reductions, enabling an iterative, results-oriented policy process. In January of 2012, the CMS team held a meeting with carbon policy and decision makers in Washington DC to describe the developing modeling system to policy makers. The NASA CMS will develop pilot studies to provide information across a range of spatial scales, consider carbon storage in biomass, and improve measures of the atmospheric distribution of carbon dioxide. The pilot involves multiple institutions (four NASA centers as well as several universities) and over 20 scientists in its work. This pilot study will generate CO2 flux maps for two years using observational constraints in NASA's state-of -the-art models. Bottom-up surface flux estimates will be computed using data-constrained land and ocean models; comparison of the different techniques will provide some knowledge of uncertainty in these estimates. Ensembles of atmospheric carbon distributions will be computed using an atmospheric general circulation model (GEOS-5), with perturbations to the surface fluxes and to transport. Top-down flux estimates will be computed from observed atmospheric CO2 distributions (ACOS/GOSAT retrievals) alongside the forward-model fields, in conjunction with an inverse approach based on the CO2 model of GEOS ]Chem. The forward model ensembles will be used to build understanding of relationships among surface flux perturbations, transport uncertainty and atmospheric carbon concentration. This will help construct uncertainty estimates and information on the true spatial resolution of the top-down flux calculations. The relationship between the top-down and bottom-up flux distributions will be documented. Because the goal of NASA CMS is to be policy relevant, the scientists involved in the flux modeling pilot need to understand and be focused on the needs of the climate policy and decision making community. If policy makers are to use CMS products, they must be aware of the modeling effort and begin to design policies that can be evaluated with information. Improving estimates of carbon sequestered in forests, for example, will require information on the spatial variability of forest biomass that is far more explicit than is presently possible using only ground observations. Carbon mitigation policies being implemented by cities around the United States could be designed with the CMS data in mind, enabling sequential evaluation and subsequent improvements in incentives, structures and programs. The success of climate mitigation programs being implemented in the United States today will hang on the depth of the relationship between scientists and their policy and decision making counterparts. Ensuring that there is two-way communication between data providers and users is important for the success both of the policies and the scientific products meant to support them..

Brown, Molly E.; Macauley, Molly

2012-01-01

436

A High Voltage Ratio and Low Ripple Interleaved DC-DC Converter for Fuel Cell Applications  

PubMed Central

This paper proposes a high voltage ratio and low ripple interleaved boost DC-DC converter, which can be used to reduce the output voltage ripple. This converter transfers the low DC voltage of fuel cell to high DC voltage in DC link. The structure of the converter is parallel with two voltage-doubler boost converters by interleaving their output voltages to reduce the voltage ripple ratio. Besides, it can lower the current stress for the switches and inductors in the system. First, the PSIM software was used to establish a proton exchange membrane fuel cell and a converter circuit model. The simulated and measured results of the fuel cell output characteristic curve are made to verify the correctness of the established simulation model. In addition, some experimental results are made to validate the effectiveness in improving output voltage ripple of the proposed high voltage ratio interleaved boost DC-DC converters. PMID:23365536

Chang, Long-Yi; Chao, Kuei-Hsiang; Chang, Tsang-Chih

2012-01-01

437

DC/DC Power Converter for Super-Capacitor Supplied by Electric Power Splitter  

NASA Astrophysics Data System (ADS)

The aim of the article is design of DC/DC converter and discussing of problematic supply using electric power splitter. The electric power splitter with AC/DC converter is source for the DC/DC converter, which is dedicated for charging and discharging of hybrid car drive super-capacitor energy storage. The electric power splitter is synchronous machine with two rotating parts. First rotor contains permanent magnet and the second rotor contains three-phase windings. The amplitude of output voltage depends on difference between first and second rotor speed. The main role of the DC/DC converter is to optimize energy content in super-capacitor storage used to acceleration and deceleration driving period of the passenger car with hybrid electric vehicle (HEV) drive system using electric power splitter.

Haubert, T.; Mindl, P.

438

Test and Evaluation of the Magnograph (TM) unit, a nondestructive wire rope tester  

NASA Astrophysics Data System (ADS)

The nondestructive wire rope test device, a unitized AC/DC Magnograph, was tested for operational characteristics prior to acquisition by Naval field activities and start of inspection programs. The Magnograph was tested for loss of metallic area (LMA) and local fault (LF) detection accuracy. Wire ropes 1/2, 3/4, 1-1/8, 1-1/2, 2, and 2-1/2 inches in diameter were tested on a wire rope test track to find the accuracy of the unit. Two mining wire ropes, guy wires of a 1,000-ft-tall tower, and wire rope for 400-, 250-, and 30-ton cranes were used to determine operational characteristics of the Magnograph.

Underbakke, L. D.; Haynes, H. H.

1982-07-01

439

Operation of a test bed axial-gap brushless dc rotor with a superconducting stator  

SciTech Connect

A variable-speed axial-gap motor with a stator consisting of four liquid helium cooled superconducting electromagnets (two pole pairs) was built and proof tested up to 608 rpm in November 1990 as a tool for joint industry-laboratory evaluation of coils fabricated from high-temperature oxide superconductors. A second rotor was fabricated with improved materia winding configuration, and wire type, and the drive system was modified to eliminate current spiking. The modified motor was characterized to design speed, 188 rad/s (1800 rpm), to acquire a performance baseline for future comparison with that of high-temperature superconducting (HIS) wire. As it becomes commercially available, HTS wire will replace the low-temperature electromagnet wire in a stator modified to control wire temperatures between 4 K and 77 K. Measurements of the superconducting electromagnetic field and locked rotor torque as functions of cryocurrent and dc current through two phases of the rotor, respectively, provided data to estimate power that could be developed by the rotor. Back emf and parasitic mechanical and electromagnetic drag torques were measured as functions of angular velocity to calculate actual rotor power developed and to quantify losses, which reduce the motor`s efficiency. A detailed measurement of motor power at design speed confirmed the developed power equation. When subsequently operated at the 33-A maximum available rotor current, the motor delivered 15.3 kill (20.5 hp) to the load. In a final test, the cryostat was operated at 2500 A, 200 A below its critical current. At rotor design current of 60 A and 2500 A stator current, the extrapolated developed power would be 44.2 kill (59.2 hp) with 94% efficiency.

McKeever, J.W.; Sohns, C.W.; Schwenterly, S.W.; Young, R.W. Sr.; Campbell, V.W.; Hickey, M.H.; Ott, G.W. [Oak Ridge National Lab., TN (United States); Bailey, J.M. [Tennessee Univ., Knoxville, TN (United States)

1993-08-01

440

Certification of offshore mooring steel wire ropes  

SciTech Connect

The trend to produce oil in increasingly deeper water has led to the development of floating production solutions for the exploitation of the energy resources in these areas. It is a fact that steel wire ropes have been used and are being proposed as line segments in the majority of the mooring systems of these units/ships. This paper specifies requirements for the materials, design, manufacture and testing of large diameter offshore mooring steel wire ropes and may serve as a technical reference document in contractual matters between the purchaser and the manufacturer. Typical applications covered are permanently moored floating production systems (FPS), offshore loading systems and mobile offshore units.

Lohne, P.W. [Det Norske Veritas AS, Oslo (Norway)

1996-12-31

441

Evolution of Upper Tropospheric Composition Perturbed by a Mesoscale Convective System during the Deep Convective Clouds and Chemistry (DC3) Campaign  

NASA Astrophysics Data System (ADS)

The role of deep convection in altering the chemical composition of the upper troposphere (UT) is well known, having been observed in many airborne campaigns, including dedicated studies that were part of the Deep Convective Clouds and Chemistry (DC3) experiment in May and June, 2012. The primary focus of DC3 was to characterize the details of transport from the boundary layer to the UT by isolated convective cells, and further to examine the evolution of air masses perturbed by the convection as chemical processing takes place the day after convective transport. These objectives were addressed by observations staged aboard the NSF/NCAR GV and NASA DC-8 aircraft platforms, which were deployed to study storms in Colorado, Oklahoma/West Texas, and northern Alabama, and to study aged outflow downwind of the storms. Because of the importance of Mesoscale Convective Systems (MCSs) in convective transport, their impact was assessed on two occasions as observations of opportunity during flights focused on other goals, and during one dedicated mission. The latter focused on a decaying nocturnal MCS that formed over the north central Great Plains and moved to the east over Illinois, Indiana, and Missouri during the day on June 21, 2012. The aircraft platforms were staged such that the DC-8 observed the aging from early morning to midday, and the GV observed from midday to early evening. The two aircraft overlapped on part of a flight leg to connect the measurements on the two platforms. This provided a 10.5 hour record of the atmospheric processing of the concentrations of a variety of gas-phase species as well as the composition and size distributions of aerosols in the outflow. By making use of air mass trajectories, the observations are placed on a photochemical age scale. This allows calculations of ozone production, production and growth of aerosols, net production of nitric acid, and budgets of HOx and its reservoirs in the MCS outflow. This provides quantitative information on the role of convection from MCSs in UT chemical composition and evolution. Flight tracks of DC-8 (magenta) and GV (yellow and red) during the MCS study on June 21, 2012. Visible and infrared satellite images near the end of the day are also shown. The numbers show the time (UTC) along the aircraft flight tracks.

Cantrell, C. A.; Barth, M. C.; Brune, W. H.; Rutledge, S. A.; Crawford, J. H.; Olson, J. R.; Flocke, F. M.

2013-12-01

442

Parametric experimental study of wire rope spring tuned mass dampers  

Microsoft Academic Search

An extensive experimental study of wire rope spring tuned mass dampers (TMDs) is presented. A single-degree-of-freedom system with a pendulum-type TMD was tested on the shaker table. The pendulum-type TMD employed wire rope spring(s) to provide both the elastic and the damping forces. The test program included two mass ratios, single- and double-sided spring arrangements, two wire rope diameters, three

Rafik R. Gerges; Barry J. Vickery

2003-01-01

443

Third NASA Workshop on Wiring for Space Applications  

NASA Technical Reports Server (NTRS)

This workshop addressed key technology issues in the field of electrical power wiring for space applications, and transferred information and technology related to space wiring for use in government and commercial applications. Speakers from space agencies, U.S. Federal labs, industry, and academia presented program overviews and discussed topics on arc tracking phenomena, advancements in insulation materials and constructions, and new wiring system topologies.

Hammoud, Ahmad (compiler); Stavnes, Mark (compiler)

1995-01-01

444

Characterization of In-Flight Processing of Alumina Powder Using a DC-RF Hybrid Plasma Flow System at Constant Low Operating Power  

NASA Astrophysics Data System (ADS)

The aim of this study is to provide the optimum operating conditions for enhancing in-flight alumina particle heating as much as possible for particle spheroidization and aggregation of melted particles using a DC-RF hybrid plasma flow system even at constant low operating power based on the thermofluid considerations. It is clarified that the swirl flow and higher operating pressure enhance the particle melting and aggregation of melted particles coupled with increasing gas temperature downstream of a plasma uniformly in the radial direction at constant electrical discharge conditions.

Nishiyama, H.; Onodera, M.; Igawa, J.; Nakajima, T.

2009-12-01

445

An open-source, FireWire camera-based, Labview-controlled image acquisition system for automated, dynamic pupillometry and blink detection.  

PubMed

The dynamic, accurate measurement of pupil size is extremely valuable for studying a large number of neuronal functions and dysfunctions. Despite tremendous and well-documented progress in image processing techniques for estimating pupil parameters, comparatively little work has been reported on practical hardware issues involved in designing image acquisition systems for pupil analysis. Here, we describe and validate the basic features of such a system which is based on a relatively compact, off-the-shelf, low-cost FireWire digital camera. We successfully implemented two configurable modes of video record: a continuous mode and an event-triggered mode. The interoperability of the whole system is guaranteed by a set of modular software components hosted on a personal computer and written in Labview. An offline analysis suite of image processing algorithms for automatically estimating pupillary and eyelid parameters were assessed using data obtained in human subjects. Our benchmark results show that such measurements can be done in a temporally precise way at a sampling frequency of up to 120 Hz and with an estimated maximum spatial resolution of 0.03 mm. Our software is made available free of charge to the scientific community, allowing end users to either use the software as is or modify it to suit their own needs. PMID:23993408

de Souza, John Kennedy Schettino; Pinto, Marcos Antonio da Silva; Vieira, Pedro Gabrielle; Baron, Jerome; Tierra-Criollo, Carlos Julio

2013-12-01

446

Dissipative Cryogenic Filters with Zero DC Resistance  

SciTech Connect

The authors designed, implemented and tested cryogenic RF filters with zero DC resistance, based on wires with a superconducting core inside a resistive sheath. The superconducting core allows low frequency currents to pass with negligible dissipation. Signals above the cutoff frequency are dissipated in the resistive part due to their small skin depth. The filters consist of twisted wire pairs shielded with copper tape. Above approximately 1 GHz, the attenuation is exponential in {radical}{omega}, as typical for skin depth based RF filters. By using additional capacitors of 10 nF per line, an attenuation of at least 45 dB above 10 MHz can be obtained. Thus, one single filter stage kept at mixing chamber temperature in a dilution refrigerator is sufficient to attenuate room temperature black body radiation to levels corresponding to 10 mK above about 10 MHz.

Bluhm, Hendrik; Moler, Kathryn A.; /Stanford U., Appl. Phys. Dept

2008-04-22

447

OrchidWire  

NSDL National Science Digital Library

Created by orchid enthusiasts Wendell and Theresa Kozak of Vancouver Island, Canada, OrchidWire website is a great resource for anyone interested in orchids. This site is an online orchid resource directory with links to 3911 images and 1184 sites in 51 countries. Site visitors can peruse orchid resources by using an alphabetical appendix or by selecting from different categories like Wild, Culture, Geographic, Genera, and many more. Specific orchid listings or images can be located by using the site search engine. Site users can also submit suggestions for addition to the OrchidWire database.

Kozak, Theresa

448

Levin and Ernst, DC Magnetic Field Effects on Development Applied DC Magnetic Fields Cause Alterations in the  

E-print Network

Levin and Ernst, DC Magnetic Field Effects on Development Applied DC Magnetic Fields Cause of interest in the interactions between electromagnetic fields and biological systems has mainly focused on AC

Levin, Michael

449

Description of real-time Ada software implementation of a power system monitor for the Space Station Freedom PMAD DC testbed  

NASA Technical Reports Server (NTRS)

The Ada language software development to perform the electrical system monitoring functions for the NASA Lewis Research Center's Power Management and Distribution (PMAD) DC testbed is described. The results of the effort to implement this monitor are presented. The PMAD DC testbed is a reduced-scale prototype of the electrical power system to be used in the Space Station Freedom. The power is controlled by smart switches known as power control components (or switchgear). The power control components are currently coordinated by five Compaq 382/20e computers connected through an 802.4 local area network. One of these computers is designated as the control node with the other four acting as subsidiary controllers. The subsidiary controllers are connected to the power control components with a Mil-Std-1553 network. An operator interface is supplied by adding a sixth computer. The power system monitor algorithm is comprised of several functions including: periodic data acquisition, data smoothing, system performance analysis, and status reporting. Data is collected from the switchgear sensors every 100 milliseconds, then passed through a 2 Hz digital filter. System performance analysis includes power interruption and overcurrent detection. The reporting mechanism notifies an operator of any abnormalities in the system. Once per second, the system monitor provides data to the control node for further processing, such as state estimation. The system monitor required a hardware time interrupt to activate the data acquisition function. The execution time of the code was optimized using an assembly language routine. The routine allows direct vectoring of the processor to Ada language procedures that perform periodic control activities. A summary of the advantages and side effects of this technique are discussed.

Ludwig, Kimberly; Mackin, Michael; Wright, Theodore

1991-01-01

450

Deciphering the transcriptional network of the DC lineage  

PubMed Central

Although, much progress has been made in our understanding of DC ontogeny and function, the transcriptional regulation of DC lineage commitment and functional specialization in vivo is poorly understood. We performed a comprehensive comparative analysis of CD8+, CD103+, CD11b+, and plasmacytoid DC subsets and the recently identified Macrophage DC precursors and Common DC precursors across the entire immune system. Here we characterize candidate transcriptional activators involved in myeloid progenitor commitment to the DC lineage and predicted regulators of DC functional diversity in tissues. We identify a molecular signature that distinguishes tissue DC from macrophages. We also identify a transcriptional program expressed specifically during steady-state tissue DC migration to the draining lymph nodes that may control tolerance to self-tissue antigens. PMID:22797772

Miller, Jennifer C; Brown, Brian D.; Shay, Tal; Gautier, Emmanuel L; Jojic, Vladimir; Cohain, Ariella; Pandey, Gaurav; Leboeuf, Marylene; Elpek, Kutlu G; Helft, Julie; Hashimoto, Daigo; Chow, Andrew; Price, Jeremy; Greter, Melanie; Bogunovic, Milena; Bellemare-Pelletier, Angelique; Frenette, Paul S.; Randolph, Gwendalyn J.; Turley, Shannon J.; Merad, Miriam

2014-01-01

451

Characteristics for Small Capacity Electric Energy Storage System with Batteries by Current Source Inverter  

NASA Astrophysics Data System (ADS)

We propose an electric energy storage system with batteries by a current source inverter. It is interconnected to the single-phase three-wire distribution system. In order to reduce the dc reactor capacity and change the discharging and the charging operations by signals, a set of DC-DC converters is added between the inverter and the batteries. In this paper, the proposed circuit configuration, the control scheme and the operating method are described, and then the discharging and the charging characteristics are discussed experimentally.

Ogura, Yasuhiro; Masukawa, Shigeo; Iida, Shoji

452

RIGBY SPECIALITY WIRES LIMITED NEW WIRE PRODUCT IS ALL  

E-print Network

RIGBY SPECIALITY WIRES LIMITED NEW WIRE PRODUCT IS ALL WRAPPED UP KTP BENEFITS Knowledge Transfer Partnerships are designed to benefit everyone involved Businesses will acquire new knowledge and expertise KTP WITH THE UNIVERSITY OF LEEDS TO DEVELOP A NEW MANUFACTURING PROCESS TO WRAP COPPER WIRE IN MICA TAPE, TO THE REQUIRED

Berzins, M.

453

Efficiency and Regulation of Commercial Low Power DC/DC Converter Modules at Low Temperatures  

NASA Technical Reports Server (NTRS)

DC/DC converters that are capable of operating at cryogenic temperatures are anticipated to play an important role in the power systems of future NASA deep space missions. Design of these converters to survive cryogenic temperatures will improve the power system performance, and reduce development and launch costs. At the NASA Glenn Research Center Low Temperature Electronics Laboratory, several commercial off-the-shelf dc/dc converter modules were evaluated for their low temperature performance. Various parameters were investigated as a function of temperature, in the range of 20 C to -190 C. Data pertaining to the efficiency and voltage regulation of the tested converters is presented and discussed.

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

2000-01-01

454

A World without Wires  

ERIC Educational Resources Information Center

The wireless bandwagon is rolling across Mississippi, picking up a fresh load of converts and turning calamity into opportunity. Traditional wired school networks, many of which unraveled during Hurricane Katrina, are giving way to advanced wireless mesh networks that frequently include voice-over-IP (VoIP) capabilities. Vendor funding is helping

Panettieri, Joseph C.

2006-01-01

455

WiredSafety  

NSDL National Science Digital Library

The Internet has afforded hundreds of millions of people the opportunity to access thousands of sites on almost every topic imaginable, and has created a myriad of new employment opportunities, interest groups, and cybercommunities. Regrettably, not every person merging onto the information superhighway is there for such laudable reasons. Stepping into the fray of n'er-do wells is the WiredSafety website, headed by Perry Aftab, an international cyberspace privacy and security lawyer and children's advocate. Registered as a non-profit organization, WiredSafety offers help for online victims of cybercrime and harassment, educational materials about cybercrime, and assistance for law enforcement worldwide on preventing and investigating cybercrimes. A good place to start on the site is Parry's Internet Safety Guide for Parents, which offers a number of helpful tips for parents about monitoring their children's interactions with others over the Internet. WiredSafety also offers Wired-Ed, which is offered free of charge and allows users to learn more about surfing the net safely. Also featured is a wide range of other online courses.

456

One-wire thermocouple  

NASA Technical Reports Server (NTRS)

Nickel alloy/constantan device accurately measures surface temperature at precise locations. Device is moderate in cost and simplifies fabrication of highly-instrumented seamless-surface heat-transfer models. Device also applies to metal surfaces if constantan wire has insulative coat.

Goodrich, W. D.; Staimach, C. J.

1977-01-01

457

Improved wire chamber  

DOEpatents

An improved gas mixture for use with proportional counter devices, such as Geiger-Mueller tubes and drift chambers. The improved gas mixture provides 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. 2 figs.

Atac, M.

1987-05-12

458

Test Results of Selected Commercial DC/DC Converters under Cryogenic Temperatures - A Digest  

NASA Technical Reports Server (NTRS)

DC/DC converters are widely used in space power systems in the areas of power management and distribution, signal conditioning, and motor control. Design of DC/DC converters to survive cryogenic temperatures will improve the power system performance, simplify design, and reduce development and launch costs. In this work, the performance of nine COTS modular, low-tomedium power DC/DC converters was investigated under cryogenic temperatures. The converters were evaluated in terms of their output regulation, efficiency, and input and output currents. At a given temperature, these properties were obtained at various input voltages and at different load levels. A summary on the performance of the tested converters was given. More comprehensive testing and in-depth analysis of performance under long-term exposure to extreme temperatures are deemed necessary to establish the suitability of these and other devices for use in the harsh environment of space exploration missions.

Patterson, Richard; Hammoud, Ahmad

2010-01-01

459

1997 wire development workshop: Proceedings  

SciTech Connect

This conference is divided into the following sections: (1) First Generation Wires I; (2) First Generation Wires II; (3) Coated conductors I; and (4) Coated conductors II. Applications of the superconducting wires include fault current limiters, superconducting motors, transformers, and power transmission lines.

NONE

1997-04-01

460

Extending wire rope service life  

SciTech Connect

Selecting the proper wire rope is not a simple procedure. Wire rope is a precision mining machine with scores of moving parts. It is therefore important for mining equipment users to know wire rope and how it is designed and constructed. Good lubrication and regular inspection is important for a safe and long service life.

Not Available

1982-06-01

461

Tungsten Wire & VISAR Goran Skoro  

E-print Network

in parallel (n=20) · Estimated temperature rise in the 0.2 mm diameter tungsten wire (at room temperature radial or/and longitudinal displacement of the wire Issues: Results of calculations -> following pages temperature; for 10m and 30m delay-leg) - flatline Conclusion: We won't see anything here #12;VISAR wire tests

McDonald, Kirk

462

Production of hot-wires  

NASA Astrophysics Data System (ADS)

Several methods for producing hot-wire probes are described. Discussion includes the manufacture of probe bodies, soldering plated wires to the prongs etching Walaston type wires, and finishing the probe. This report is written as an instruction manual for researchers who desire to produce or repair their own sensors.

Dickinson, S. C.

1983-04-01

463

Electrical explosion of segmented wires  

Microsoft Academic Search

The phenomena occurring during the electrical explosion of segmented wires are described. It was observed that with a wire of varying thickness, the smaller diameter parts explode first, ejecting metal vapor radially. Breakdown occurs through the vapor, creating current carrying channels which bypass the larger diameter parts of the wire. This may result, in some cases, in the larger diameter

Y. Me-Bar; R. Harel

1996-01-01

464

Composite ceramic superconducting wires for electric-motor applications. Quarterly report No. 9, 1 July-30 September 1990  

SciTech Connect

A scaled-up process for producing sintered, silver-coated YBCO mono filament wire has been 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: (1) Continuously melt-texturing sintered YBCO wire/fiber to produce a macro-crystalline, strong-linked wire, and (2) Adapt 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, J.D.

1990-09-30

465

STRS SpaceWire FPGA Module  

NASA Technical Reports Server (NTRS)

An FPGA module leverages the previous work from Goddard Space Flight Center (GSFC) relating to NASA s Space Telecommunications Radio System (STRS) project. The STRS SpaceWire FPGA Module is written in the Verilog Register Transfer Level (RTL) language, and it encapsulates an unmodified GSFC core (which is written in VHDL). The module has the necessary inputs/outputs (I/Os) and parameters to integrate seamlessly with the SPARC I/O FPGA Interface module (also developed for the STRS operating environment, OE). Software running on the SPARC processor can access the configuration and status registers within the SpaceWire module. This allows software to control and monitor the SpaceWire functions, but it is also used to give software direct access to what is transmitted and received through the link. SpaceWire data characters can be sent/received through the software interface, as well as through the dedicated interface on the GSFC core. Similarly, SpaceWire time codes can be sent/received through the software interface or through a dedicated interface on the core. This innovation is designed for plug-and-play integration in the STRS OE. The SpaceWire module simplifies the interfaces to the GSFC core, and synchronizes all I/O to a single clock. An interrupt output (with optional masking) identifies time-sensitive events within the module. Test modes were added to allow internal loopback of the SpaceWire link and internal loopback of the client-side data interface.

Lux, James P.; Taylor, Gregory H.; Lang, Minh; Stern, Ryan A.

2011-01-01

466

Derivation of Instantaneous Wye and Zero-Phase Sequence Voltages from Line-Line Voltages in Unbalanced 3-Phase 3-Wire Systems and Application of This Method to 3-Phase PWM Converter Control  

NASA Astrophysics Data System (ADS)

In general, voltage imbalances in 3-phase AC power systems are inevitable. 3-Phase PWM (Pulse Width Modulation) converter used in 3-wire systems are generally designed for use under limited imbalances of input voltages, and problems such as input current distortion, deterioration of output properties, degradation of efficiency and failure may occur in some cases. These problems cause severe damages to industries in some cases, for example, semiconductor production machines: SEMI defined SEMI F47-0200 and SEMI F47-0706 standards that have to be satisfied to realize voltage sag immunity. In order to compensate the remained problems due to the unbalanced input voltages, particular storage devices are designed additionally for conventional converters. This paper proposes that the determination of both the instantaneous zero-phase sequence voltage and wye voltages is essential for 3-phase PWM converter control used for a 3-wire system to keep its output rated under occasional or long-term voltage imbalances in an AC system. This paper also describes a general new method to derive the components of the voltages of instantaneous wye and zero-phase sequence voltage from line-line voltages of a 3-wire system. This paper also describes a method to apply the voltages to control the converter. The results obtained on implementation verify that this new converter keeps its output rated under unbalanced conditions wider than those defined by SEMIs without particular storage devices as far as the AC voltages are remained live.

Yuzurihara, Itsuo; Kawamura, Atsuo

467

The Fiscal Impact of the D.C. Voucher Program  

ERIC Educational Resources Information Center

In August 2004 the first ever federally funded school voucher program began in Washington, D.C. Eligible students could attend a private school of their choice in the District of Columbia. Each participant received up to $7,500 for school tuition, fees, and transportation. In addition, the D.C. Public School System (DCPS) and D.C. charter school

Aud, Susan L.; Michos, Leon

2006-01-01

468

Body Temperature Monitor and Alarm System Used in Hospital Based on 1Wire and Wireless Communication Technology  

Microsoft Academic Search

Body temperature measurement has very important meaning in clinic diagnosis and treatment. Due to traditional artificial measurement style has mangy disadvantages such as long measurement time, and low measurement precision, etc, which is hard to automatically and accurately monitor patient body temperature in real time. Aiming to this problem, paper introduces a kind of body temperature distributed monitor system. Multi-temperature

Yu Chen; Haijun Zhang; Na Wang

2008-01-01

469

Use of a Nonequilibrium MHD Generator for Conversion of SNTP Nuclear Thermal Rocket Exhaust to DC Electric Power for a Multimegawatt Nuclear Electric Propulsion System  

NASA Astrophysics Data System (ADS)

This paper explores a method by which the energy of a high speed flowing gas can efficiently be converted into DC electric power by a magnetohydrodynamic (MHD) generator. A nonequilibrium state may be created in the working fluid during the ionization process using an arc discharge. This nonequilibrium state may possibly be sustained in the fluid using the waste heat byproduct of the natural operation of the generator, if certain characteristics of the fluid/MHD system are maintained. The improved efficiency of the resulting nonequilibrium MHD generator not only allows the system to deliver increased power to the load, but reduces the amount of energy to be expelled from the closed fluid cycle by a radiator.

Finley, Charles J.

1994-07-01

470

Design and control of a Nitinol wire actuated rotary servo  

NASA Astrophysics Data System (ADS)

This paper presents the design and control of a rotary servo actuated by a shape memory alloy (SMA) wire. A new rotary servo device using Nitinol type of SMA wire is designed and fabricated in this study. This new rotary actuator utilizes a Nitinol wire wound on a threaded non-conductive rotor. One end of the Nitinol wire is fixed to the rotor and the other end is fixed to the supporting base plate. The rotor is connected to a pre-tensioned torsional spring such that two-way rotation can be achieved. Upon heating of the Nitinol wire using electric current, the wire contracts, causing the rotor to rotate, since the other end of the SMA wire is rigidly connected to the base plate. This rotor design is compact and offers a space-saving solution for the use of SMA wire actuators. To actively control the servo, a sliding-mode based robust control approach is used. The sliding-mode based robust control consists of three components: a standard proportional plus derivative (PD) control term, a feedforward term used as a bias current, and a robust term to increase system stability and concurrently control accuracy. Experimental results confirm the functionality of the Nitinol wire actuated rotary servo and show this device can be precisely controlled using the sliding-mode based robust control approach.

Song, G.

2007-10-01

471

RF-to-DC Characteristics of Direct Irradiated On-Chip Gallium Arsenide Schottky Diode and Antenna for Application in Proximity Communication System  

PubMed Central

We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the reduction of series resistance and parallel connection of diode and load tend to lead to the improvement of RF-to-DC conversion efficiency. Under direct irradiation from antenna-to-antenna method, the output voltage of 35 mV was still obtainable for the distance of 8 cm between both antennas in spite of large mismatch in the resonant frequency between the diode and the connected antenna. Higher output voltage in volt range is expected to be achievable for the well-matching condition. The proposed on-chip AlGaAs/GaAs HEMT Schottky diode and antenna seems to be a promising candidate to be used for application in proximity communication system as a wireless low power source as well as a highly sensitive RF detector. PMID:24561400

Mustafa, Farahiyah; Hashim, Abdul Manaf

2014-01-01

472

RF-to-DC characteristics of direct irradiated on-chip gallium arsenide Schottky diode and antenna for application in proximity communication system.  

PubMed

We report the RF-to-DC characteristics of the integrated AlGaAs/GaAs Schottky diode and antenna under the direct injection and irradiation condition. The conversion efficiency up to 80% under direct injection of 1 GHz signal to the diode was achieved. It was found that the reduction of series resistance and parallel connection of diode and load tend to lead to the improvement of RF-to-DC conversion efficiency. Under direct irradiation from antenna-to-antenna met