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1

Modeling of magnetic vibrational energy harvesters using equivalent circuit representations  

NASA Astrophysics Data System (ADS)

This paper develops and analyzes an equivalent circuit model of magnetic energy harvesters using reduced-order lumped element modeling (LEM) methods. This model is intended to enhance the design and analysis of a magnetic energy harvesting system by enabling direct physical insight into the system dynamics and simple circuit analysis techniques to extract all relevant performance parameters. Moreover, the model provides the ability to use circuit simulation software (e.g. PSPICE) to model the entire system in conjunction with nonlinear and/or active power electronic circuits. The circuit model is experimentally validated through electrical and mechanical measurements on a prototypical electromagnetic energy harvester.

Cheng, Shuo; Wang, Naigang; Arnold, David P.

2007-11-01

2

Modeling of magnetic vibrational energy harvesters using equivalent circuit representations  

Microsoft Academic Search

This paper develops and analyzes an equivalent circuit model of magnetic energy harvesters using reduced-order lumped element modeling (LEM) methods. This model is intended to enhance the design and analysis of a magnetic energy harvesting system by enabling direct physical insight into the system dynamics and simple circuit analysis techniques to extract all relevant performance parameters. Moreover, the model provides

Shuo Cheng; Naigang Wang; David P. Arnold

2007-01-01

3

Magnetizing circuit model for EMTP including voltage dependence characteristic  

Microsoft Academic Search

This paper proposes a numerical magnetizing circuit model of an iron core including its voltage dependence. The proposed model logically consists of a saturatable R-L parallel circuit and a correction term that expresses the voltage dependence. The characteristic of the nonlinear inductor is determined by a magnetization curve. The correction term for the inductive current is defined as a function

N. Nagaoka; S. Tawada; A. Ametani

2002-01-01

4

Solution to magnetic circuits by means of mathematical modeling  

NASA Astrophysics Data System (ADS)

In the paper, authors describe results of their analysis using the numeric simulation of magnetic circuits of the flaw detecting apparatus for nondestructive checking of steel wire ropes by means of the finite element method. There were created not only 2D (rotationally symmetric model), but also 3D type models. The main goal of the work was to get the response of typical defects on wires located inside and on the surface of ropes. In order to get better response, various alternatives of magnetic circuits with different types of permanent magnets were evaluated. Materials used for flaw detecting apparatus construction as well as the geometry of the whole flaw detecting apparatus were studied in detail. These computations were performed on SGI computer with internal memory of 64 MB. Also, a computer type IBM SP/2 has been used. The models were created by using of the software ANSYS package.

Les?ák, Michal; Les?ák, Oldrich

1999-12-01

5

3-D Magnetic Equivalent Circuit Framework for Modeling Electromechanical Devices  

Microsoft Academic Search

Magnetic equivalent circuits (MECs) are becoming an accepted alternative to electrical-equivalent lumped-parameter models and finite-element analysis (FEA) for simulating electromechanical devices. Their key advantages are moderate computational effort, reasonable accuracy, and flexibility in model size. MECs are easily extended into three dimensions. But despite the successful use of MEC as a modeling tool, a generalized 3-D formulation useable for a

Marco Amrhein; Philip T. Krein

2009-01-01

6

A new nonlinear magnetic circuit model for dynamic analysis of interior permanent magnet synchronous motor  

NASA Astrophysics Data System (ADS)

Interior permanent magnet synchronous motors (IPMSMs) have high efficiency and torque, since the motors can utilize reluctance torque in addition to magnet torque. The IPMSMs are widely used for electric household appliances and electric bicycles and vehicles. A quantitative analysis method of dynamic characteristics of the IPMSMs, however, has not been clarified fully. For optimum design, investigation of dynamic characteristics considering magnetic nonlinearity is needed. This paper presents a new nonlinear magnetic circuit model of an IPMSM, and suggests a dynamic analysis method using the proposed magnetic circuit model.

Nakamura, Kenji; Saito, Kenichi; Watanabe, Tadaaki; Ichinokura, Osamu

2005-04-01

7

A model for coupled magnetic-electric circuits in electric machines with skewed slots  

Microsoft Academic Search

A model permitting the simulation of skewed-slot saturated machines associated with nonlinear external circuits is proposed. To take the slot effects into account, the magnetic circuit is modeled through the combined two-dimensional calculations along the machine axis. In this simulation the electric circuit equation is directly coupled with the magnetic one. The solution of the resulting nonlinear time-dependent equation is

F. Piriou; A. Razek

1990-01-01

8

A coupling between electric circuits and 2D magnetic field modeling  

Microsoft Academic Search

A method which enables coupling between equations of electric circuits consisting of a lumped element RLC configuration and a magnetic field model is presented. The coupling between the finite-element and the boundary-element methods is used to compute the magnetic field produced by conductors excited by an electric circuit. The conductors involved in this computation may be connected according to any

A. Nicolet; F. Delince; N. Bamps; A. Genon; W. Legros

1993-01-01

9

A non-linear coupled 3D model for magnetic field and electric circuit equations  

Microsoft Academic Search

The authors propose a 3-D numerical model in which the magnetic field and electric circuit equations in the absence of eddy currents are solved simultaneously. To consider the magnetic equations, use is made of a magnetic vector potential formulation with the gauge condition (A.w=0) which makes it possible to reduce the number of unknowns. To take into account the magnetic

F. Piriou; A. Razek

1992-01-01

10

Analytical Modeling and Analysis of Open-Circuit Magnet Loss in Surface-Mounted Permanent-Magnet Machines  

Microsoft Academic Search

The paper presents an analytical model for predicting the open-circuit magnet eddy-current loss due to slotting in surface-mounted permanent-magnet machines based on the exact subdomain field model. The spatial and temporal characteristics of field harmonics due to slotting and corresponding eddy-current harmonics in the magnet are analyzed in both stator and rotor reference frames. The contribution of interaction between eddy-current

L. J. Wu; Z. Q. Zhu; D. Staton; M. Popescu; D. Hawkins

2012-01-01

11

Magnetic switches and circuits  

SciTech Connect

This report outlines the use of saturable inductors as switches in lumped-element, magnetic-pulse compression circuits is discussed and the characteristic use of each is defined. In addition, the geometric constraints and magnetic pulse compression circuits used in short-pulse, low-inductance systems are considered. The scaling of presaturation leakage currents, magnetic energy losses, and switching times with geometrical and material parameters are developed to aid in evaluating magnetic pulse compression systems in a particular application. Finally, a scheme for increasing the couping coefficient in saturable stripline transformers is proposed to enable their use in the short-pulse, high-voltage regime.

Nunnally, W.C.

1982-05-01

12

A Magnetic Circuit Demonstration.  

ERIC Educational Resources Information Center

|Presents a demonstration designed to illustrate Faraday's, Ampere's, and Lenz's laws and to reinforce the concepts through the analysis of a two-loop magnetic circuit. Can be made dramatic and challenging for sophisticated students but is suitable for an introductory course in electricity and magnetism. (JRH)|

Vanderkooy, John; Lowe, June

1995-01-01

13

Equivalent-circuit models for the design of metamaterials based on artificial magnetic inclusions  

Microsoft Academic Search

In this paper, we derive quasi-static equivalent-circuit models for the analysis and design of different types of artificial magnetic resonators—i.e., the multiple split-ring resonator, spiral resonator, and labyrinth resonator—which represent popular in- clusions to synthesize artificial materials and metamaterials with anomalous values of the permeability in the microwave and mil- limeter-wave frequency ranges. The proposed models, derived in terms of

Filiberto Bilotti; Alessandro Toscano; Lucio Vegni; Koray Aydin; Kamil Boratay Alici; Ekmel Ozbay

2007-01-01

14

Magnetic compression laser driving circuit  

DOEpatents

A magnetic compression laser driving circuit is disclosed. The magnetic compression laser driving circuit compresses voltage pulses in the range of 1.5 microseconds at 20 Kilovolts of amplitude to pulses in the range of 40 nanoseconds and 60 Kilovolts of amplitude. The magnetic compression laser driving circuit includes a multi-stage magnetic switch where the last stage includes a switch having at least two turns which has larger saturated inductance with less core material so that the efficiency of the circuit and hence the laser is increased.

Ball, Don G. (Livermore, CA); Birx, Dan (Brentwood, CA); Cook, Edward G. (Livermore, CA)

1993-01-01

15

Magnetically Undetectable Electronic Circuit Assemblies.  

National Technical Information Service (NTIS)

This report describes the results of work concerned with fabricating, electronic circuit assemblies which are undetectable magnetically, and contains recommendations concerning further development work. (Author)

H. Morris

1980-01-01

16

Asymmetric Circuit Models and Parameter Measurement for PermanentMagnet Linear Synchronous Motor Considering Inductance Harmonics and Saliency  

NASA Astrophysics Data System (ADS)

This paper presents asymmetric circuit models and an inductance parameter measurement method for Permanent Magnet Linear Synchronous Motors (PMLSMs). The reason why the tested PMLSM with surface permanent magnet structure exhibits both asymmetry and salient pole natures is investigated. Asymmetric circuit models considering the saliency and inductance harmonic effects are discussed for PMLSM fed by three-phase three-wire power source systems. All fundamental and harmonic inductance parameters are easily determined by a standstill test using a single-phase commercial source. Experimental and simulation results on a single-sided PMLSM with a 3-phase, 4-pole and 14-slot mover demonstrate the validity of the proposed method.

Yamamoto, Shu; Yamaguchi, Tomonobu; Hirahara, Hideaki; Ara, Takahiro

17

Simulation of magnetic component models in electric circuits including dynamic thermal effects  

Microsoft Academic Search

It is essential in the simulation of power electronics applications to model magnetic components accurately. In addition to modeling the nonlinear hysteresis behavior, eddy currents and winding losses must be included to provide a realistic model. In practice the losses in magnetic components give rise to significant temperature increases which can lead to major changes in the component behavior. In

Peter R. Wilson; J. Neil Ross; Andrew D. Brown

2002-01-01

18

A Differential Magnetic Circuit for Teaching Purposes  

ERIC Educational Resources Information Center

|A differential magnetic circuit (magnetic bridge) is described. The circuit separates the magnetic field sensor and the sample under study. A Hall probe serves as the sensor. The signal from the sensor can be enhanced by concentrating the magnetic flux. The magnetic bridge works even with dc magnetic fields. The device is used for displaying…

Kraftmakher, Yaakov

2010-01-01

19

Field–circuit coupled models in electromagnetic simulation  

Microsoft Academic Search

A general field–circuit coupling mechanism for electromagnetic models is presented. The topological treatment of the circuit allows for a well-defined choice of coupling unknowns and equations, both for couplings of magnetic fields to magnetic circuits and couplings of magnetic fields to electric circuits. The properties of the resulting systems of equations are studied and appropriate iterative solution techniques are proposed.

Herbert De Gersem; Kay Hameyer; Thomas Weiland

2004-01-01

20

RC Circuit Model  

NSDL National Science Digital Library

RC Circuit models the dynamical behavior of a voltage source attached in series to a resistor and capacitor. The source voltage can be chosen to be either a 10 volt sinusoidal or square wave with an adjustable frequency. Users can examine and change the model if they have Ejs installed. The RC Circuit model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RcCircuit.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2009-10-05

21

Modeling of transformers using circuit simulators  

NASA Astrophysics Data System (ADS)

Transformers of two different designs, an unencapsulated pot core and an encapsulated toroidal core, have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim's PSPICE and Anology's SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.

Archer, W. E.; Deveney, M. F.; Nagel, R. L.

22

Modeling of transformers using circuit simulators  

SciTech Connect

Transformers of two different designs; and unencapsulated pot core and an encapsulated toroidal core have been modeled for circuit analysis with circuit simulation tools. We selected MicroSim`s PSPICE and Anology`s SABER as the simulation tools and used experimental BH Loop and network analyzer measurements to generate the needed input data. The models are compared for accuracy and convergence using the circuit simulators. Results are presented which demonstrate the effects on circuit performance from magnetic core losses, eddy currents, and mechanical stress on the magnetic cores.

Archer, W.E.; Deveney, M.F.; Nagel, R.L.

1994-07-01

23

Magnetic moments in biased quantum circuits  

NASA Astrophysics Data System (ADS)

We consider a quantum ring connected to leads and the current which is excited by biasing the circuit in the absence of external magnetic field. The magnetic moment Mring that arises in this way depends on the current distribution inside the ring. We perform a thought experiment in which Mring is determined by measuring the torque due to an infinitesimally small probe magnetic field. This leads to a definition Mring , which is given by the derivative of the grand-canonical energy of the quantum ring with respect to an external magnetic flux in the zero flux limit. We develop the many-body formalism by Green’s-function techniques and carry on illustrative model calculations. The resulting theory predicts that at small bias the current in the ring is always laminar, that is, the magnetic moment vanishes in linear-response theory. The approach most naturally lends itself to include induction effects by a self-consistent procedure.

Cini, Michele; Perfetto, Enrico; Stefanucci, Gianluca

2010-04-01

24

Double Integrator Magnetic Amplifier Output Circuit.  

National Technical Information Service (NTIS)

The magnetic amplifier has an integrating circuit adapted to produce a sinusoidal output voltage. Two properly rated integrating circuits are applied to the output of a push-pull magnetic amplifier. An output current may be provided flowing through the ex...

W. A. Geyher

1965-01-01

25

Development of a miniature permanent magnetic circuit for nuclear magnetic resonance chip  

NASA Astrophysics Data System (ADS)

The existing researches of miniature magnetic circuits focus on the single-sided permanent magnetic circuits and the Halbach permanent magnetic circuits. In the single-sided permanent magnetic circuits, the magnetic flux density is always very low in the work region. In the Halbach permanent magnetic circuits, there are always great difficulties in the manufacturing and assembly process. The static magnetic flux density required for nuclear magnetic resonance(NMR) chip is analyzed based on the signal noise ratio(SNR) calculation model, and then a miniature C-shaped permanent magnetic circuit is designed as the required magnetic flux density. Based on Kirchhoff's law and magnetic flux refraction principle, the concept of a single shimming ring is proposed to improve the performance of the designed magnetic circuit. Using the finite element method, a comparative calculation is conducted. The calculation results demonstrate that the magnetic circuit improved with a single shimming has higher magnetic flux density and better magnetic field homogeneity than the one improved with no shimming ring or double shimming rings. The proposed magnetic circuit is manufactured and its experimental test platform is also built. The magnetic flux density measured in the work region is 0.7 T, which is well coincided with the theoretical design. The spatial variation of the magnetic field is within the range of the instrument error. At last, the temperature dependence of the magnetic flux density produced by the proposed magnetic circuit is investigated through both theoretical analysis and experimental study, and a linear functional model is obtained. The proposed research is crucial for solving the problem in the application of NMR-chip under different environmental temperatures.

Lu, Rongsheng; Yi, Hong; Wu, Weiping; Ni, Zhonghua

2013-07-01

26

High-Speed Magnetic Air Circuit Breaker for Distribution Circuits  

Microsoft Academic Search

Field tests indicate that very fast clearing of faults on 4-kv open-wire distribution circuits will materially reduce wire burndowns and consequently improve the service interruption record. Heretofore, the fastest air circuit breakers available for this service, exclusive of compressed-air breakers, have interrupting times of 3½ to 5½ cycles. A magnetic-type air breaker with 1½ to 2 cycles interrupting time is

H. P. Sleeper; J. D. Findley

1959-01-01

27

Approaches to permanent magnet circuit design  

Microsoft Academic Search

Discusses some of the more fruitful approaches to the use of high coercivity\\/high remanence magnet materials in magnetic circuit design and how the application of comparatively few and simple techniques can result in a large number of useful devices. The approaches discussed are the estimation of permeances, magnetic cladding, equivalent pole densities and current sheets, analytic application of Maxwell's equations,

Herbert A. Leupold

1993-01-01

28

Designing HTS coils for magnetic circuits  

SciTech Connect

The authors discuss some of the main considerations involved in the design of HTS coils to operate in liquid nitrogen and provide ampere-turns for magnetic circuits in general, and then in particular for a small-scale electromagnetic (i.e, attractive) maglev demonstrator. The most important factor affecting design is the sensitive and strongly anisotropic dependence of HTS tape`s critical current on magnetic field. Any successful design must limit the field in the windings, especially components perpendicular to the tape`s surface (radial components in the case of solenoids), to acceptably low levels such that local critical currents nowhere fall below the operating current. This factor is relevant to the construction of HTS coils for all applications. A second important factor is that the presence of an iron magnetic circuit can greatly alter the flux distribution within the coils from that found when they are in free space. FE modelling has been used to calculate accurate field profiles in proposed designs for comparison with short sample I{sub c}(B) data. They present a design for a maglev demonstrator, illustrating how some of the problems, in particular the reduction of radial field components, may be addressed, and describe its predicted performance.

Jenkins, R.G.; Jones, H. [Univ. of Oxford (United Kingdom). Clarendon Lab.; Goodall, R.M. [Loughborough Univ. of Technology (United Kingdom). Dept. of Electronic and Electrical Engineering

1996-07-01

29

Antenna coupling circuit for magnetic resonance imaging  

SciTech Connect

A coupling circuit for coupling an inductive coil antenna of a magnetic resonance imaging system to receiver circuitry is described comprising: capacitive means, coupled in parallel with the antenna, for providing capacitive reactance in the coupling circuit; resistive means, coupled in parallel with the antenna and with the capacitive means, for providing resistance R in the coupling circuit when the inductive reactance of the coupling circuit is equal to the capacitive reactance of the coupling circuit; and capacitive transformer means, coupled between the antenna and the receiver circuitry in series with the antenna, for transforming the resistance value R of the resistive means into a transformed resistance value R', thereby increasing the apparent resistance of the coupling circuit in parallel with the antenna.

Fox, T.R.

1988-03-15

30

RC Circuit with Battery Model  

NSDL National Science Digital Library

The RC Circuit with Battery model investigates a circuit involving a resistor R and capacitor C and a battery. The resistor and capacitor are in series with one another and a battery is switched in series with both components or switched out of the circuit. The RC Circuit with Battery model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_duffy_RC.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-22

31

Coupled problem computation of 3-D multiply connected magnetic circuits and electrical circuits  

Microsoft Academic Search

This paper presents the theory and the validation of a new finite-element formulation to realize the coupling between electrical circuits and multiply connected magnetic circuits, using a magnetic scalar potential as state variable. For this purpose, we used formulations in reduced magnetic scalar potential versus T0 taking into account electrical circuits and a total magnetic scalar potential taking into account

Yann Le Floch; Gérard Meunier; Christophe Guérin; Patrice Labie; Xavier Brunotte; Dominique Boudaud

2003-01-01

32

Didactic Considerations on Magnetic Circuits Excited by Permanent Magnets  

ERIC Educational Resources Information Center

|In this paper, the authors focus their attention on the way magnetic circuits and permanent magnets are usually treated in most textbooks and electrical engineering courses. This paper demonstrates how this important topic is too often presented simplistically. This simplistic treatment does not allow the students to develop a complete…

Barmada, S.; Rizzo, R.; Sani, L.

2009-01-01

33

Magnetic-spiker electrical circuits for gas discharge lasers  

NASA Astrophysics Data System (ADS)

Magnetic-spiker electrical circuits for gas discharge lasers are described. A new modified overshoot mode of magnetic-spiker XeCl laser excitation is presented as a possible circuit for high repetition rate operation. PSPICE computer simulations of a number of magnetic-spiker XeCl laser circuits are compared with experimental results.

Taylor, Roderick S.; Leopold, Kurt E.; von Dadelszen, M.

1994-08-01

34

Modeling of transients in permanent magnet generators with multiple damping circuits using the natural abc frame of reference  

Microsoft Academic Search

A computer-aided method for modeling the transient performance of permanent magnet generators and determining their parameters is presented. The method is based on the development and use of state models in the natural abc frame of reference, in which the abc machine-winding parameters were determined from combined energy-current perturbation and finite-element magnetic field computation methods. The method is applied to

A. A. Arkadan; N. A. Demerdash

1988-01-01

35

Nonlinear varying-network magnetic circuit analysis for doubly salient permanent-magnet motors  

Microsoft Academic Search

In this paper, a nonlinear varying-network magnetic circuit (VNMC) modeling method is developed for doubly salient permanent-magnet (DSPM) motors. The method is used to analyze the static characteristics of DSPM motors by specific performance calculations, in which the interaction between the permanent-magnet field and the armature current field, as well as magnetic saturation, are taken into account. Two newly proposed

Ming Cheng; K. T. Chau; C. C. Chan; E. Zhou; X. Huang

2000-01-01

36

Magnetic circuit design for miniaturized magnetic shape memory alloy actuators  

NASA Astrophysics Data System (ADS)

Magnetic shape memory alloy (MSMA) is a relatively new kind of smart material. Upon application of a large magnetic field, it exhibits actuation strains up to 10% similar to thermal shape memory alloy (SMA) but shows significantly reduced response time in the millisecond range. Currently, application is restricted by the brittleness of the single crystal material, its nonlinear behaviour and the difficulty to generate and apply a magnetic field around 0.6T in order to exploit the full actuation potential. The focus of this work is on the design of miniaturized magnetic circuits for bulk MSMAs. Various circuit designs are compared such as toroidal and series-parallel shapes. Equivalent circuit as well as finite element simulation is used to increase the magnetic field in a characteristic air gap where the smart material is placed. A symmetrical toroid coil layout with the MSMA element at the center that allows easy integration of the actuator in various applications is described. Static characterization results of this actuator are provided. Using the described magnetic circuit and 5M - MSMA rods with dimensions of 20x2.5x1mm3, a peak displacement of 0.8mm and a blocked force of 4.5N was obtained. Further design guidelines for such miniaturized actuators are given.

Bolzmacher, C.

2013-05-01

37

Equivalent circuit models for the analysis of electric response and magnetic response of compact triangular electromagnetic resonator  

NASA Astrophysics Data System (ADS)

The equivalent circuit model (ECM) and the design of compact triangular electromagnetic resonator (TER) are both introduced in this paper. ECM with analytic expressions is utilized to obtain the dispersion curves of effective permittivity and effective permeability of four kinds of TER with/without interdigital capacitor. Compared with effective parameters obtained by the parametric retrieval algorithm using simulated and measured s-parameters, the results of ECM correspond very well with the two results above, which demonstrates the effectiveness of ECM and provides us a new way to analyze the effective parameters of metamaterials.

Zhu, Cheng; Li, Ke; Chen, Yang; Li, Tong; Zhai, Hui-Qing; Li, Long; Liang, Chang-Hong

2013-01-01

38

CMOS magnetic sensor integrated circuit with sectorial MAGFET  

Microsoft Academic Search

In this paper, a CMOS magnetic sensor integrated circuit (IC) for a perpendicular magnetic field is introduced. The sensor integrated circuit is designed and fabricated in a 0.6?m digital CMOS process. It consists of a pair of common-source split-drain magnetic field-effect transistor (MAGFET), a pre-processing circuit with a switches array, a correlated double sampling (CDS) circuit and a digital controlling

Guo Qing; Zhu Dazhong; Yao Yunruo

2006-01-01

39

New equivalent circuit of three-phase three-limb transformer based on magnetic circuit characteristics  

Microsoft Academic Search

Due to the characteristics of three-phase three-limb transformer core topology, its magnetic flux can be represented by leakage inductances, column leakage inductances and mutual inductances. Based on this representation, a new equivalent circuit model of three-phase three-limb transformer is proposed in this paper. The distinguishing feature of the new model is that the operating mechanism of three-phase three-limb transformer can

JiaLe Suonan; Liqiang Xu; ZaiBin Jiao

2011-01-01

40

Adaptive modeling of electronic circuits  

NASA Astrophysics Data System (ADS)

Adaptive simulation is a method for enhancing the efficiency of software facilities for the computer-aided design of LSI and VLSI ciruits. This paper examines the formulation and main principles of the implementation of this method, which consists in the automatic selection of the most appropriate model for each fragment of the large-scale circuit in the course of computations. Methods for solving the three basic problems of adaptive simulation are proposed: the choice of a criterion for changing models; determination of initial (at the moment of change) values of the state variables; and the separation of the circuit into fragments.

Norenkov, I. P.; Somov, P. A.

1984-11-01

41

Numerical Calculation of Torque Transmission and Magnetic Circuit Finite Element Analysis of a Magnetorheological Clutch  

Microsoft Academic Search

To obtain the transmission characteristics of a magnetorheological clutch, the torque transmission model of the clutch is deduced based on the Bingham model considering the uniformity of magnetic flux density in the working gap, the distribution of magnetic flux density is analyzed by the magnetic circuit finite element method, the influence rules of structural factors on magnetic flux density are

Hou You Fu; Tian Zu Zhi; Wang Nan Nan

2010-01-01

42

Semiconductor Circuit Diagnostics By Magnetic Field Imaging  

NASA Astrophysics Data System (ADS)

At the forefront of IC technology development are 3D circuit technologies such as system-in-package (SiP), wafer-level-packaging (WLP), through-silicon-vias (TSV), stacked die approaches, flex packages, etc. They integrate multiple devices, many times stacking them in layers with complex, intricate and very long interconnections in significantly reduced area, in addition to an ever-increasing number of opaque layers. We could very well say that the near future looks like the perfect nightmare for the Failure Analysis (FA) engineer with localization of defects becoming a major challenge. Magnetic field imaging (MFI) allows the fields generated by the circuit currents to go through various packaging layers and be imaged. I will describe in this talk Magma, a scanning magnetic field imaging system based on a high temperature superconducting SQUID device based on YBa2Cu3O7-?. The HTS SQUIDs used have a noise level of ˜ 20pT/(Hz) and for typical scanning conditions, a field sensitivity of about 0.7 nT. While current shorts are imaged with spatial resolution, up to 3 micron (with peak localization) resistive opens can also be imaged and currently different strategies are being adapted for imaging opens with large working distances of 50-100s of microns. Higher spatial resolution (˜250nm) is obtained by the use of magneto-resistive devices as sensors though the working distance requirement is sever

Venkatesan, T.

2011-03-01

43

Resonant circuit as magnetic device for cancer therapy  

NASA Astrophysics Data System (ADS)

Fabrication and characterization of a resonant circuit as magnetic device for hyperthermia treatment are discussed. The resonant circuit consisting of a closed connection of an inductor and a capacitor raised its temperature by an externally applied magnetic field. As the resonant circuit was heated efficiently, it could be excited by a weak RF magnetic field of magnetic resonance imaging (MRI). By using a ferrite core for the inductor, the efficiency of temperature rise of the circuit was improved, which attributed to the miniaturization of the implant size.

Takemura, Yasushi

2011-01-01

44

Modeling of electromagnetic circuit of a magnetorheological fluid clutch  

Microsoft Academic Search

The steady-state and transient accuracy of magnetorheological fluid (MRF) clutch torque control is affected by the magnetic hysteresis and eddy current lag. The paper presents a nonlinear analytical model of the MRF clutch electromagnetic circuit dynamics. The model includes two state variables describing the combined solenoid and eddy current dynamics, and the dynamics induced by the magnetic hysteresis effect. The

J. Deur; Z. Herold; M. Kostelac

2009-01-01

45

Integrated circuit ac mutual inductance bridge for magnetic susceptibility measurements  

Microsoft Academic Search

A versatile ac mutual inductance bridge is described which uses integrated circuit operational amplifiers (op-amps) for the measurement of magnetic susceptibilities of ferro-, ferri-, and para-magnetic samples. The circuit employs op-amps both for balancing the bridge and for detecting the differential signal from the sample coil. The response of the circuit is linear over a wide range of sample susceptibilities,

C. M. Brodbeck; R. R. Bukrey; J. T. Hoeksema

1978-01-01

46

Magnetoelectric sensor with miniature universal tunable bias magnetic circuit  

NASA Astrophysics Data System (ADS)

This paper presents a miniature alternating magnetic field sensor made from magnetoelectric (ME) laminated materials with a universal tunable bias magnetic circuit. By adjusting the width of the bypass passage in the bias magnetic circuit, the magnetic flux in the ME materials could be tuned and make the ME sensor work under the optimal bias magnetic field. In our design, the sensor's dimension is as small as 8 mm along the detecting direction. Due to the excellent linearity when measuring low frequency alternating magnetic fields of 50 Hz, this miniature sensor is ideally suited for power line current measurement.

Shi, Zhan; Tong, Yongshuai; Deng, Shuwen; Xue, Hao; Yang, Shuiyuan; Lu, Yong; Wang, Cuiping; Liu, Xingjun

2013-07-01

47

Magnetic force microscopy method and apparatus to detect and image currents in integrated circuits  

DOEpatents

A magnetic force microscopy method and improved magnetic tip for detecting and quantifying internal magnetic fields resulting from current of integrated circuits. Detection of the current is used for failure analysis, design verification, and model validation. The interaction of the current on the integrated chip with a magnetic field can be detected using a cantilevered magnetic tip. Enhanced sensitivity for both ac and dc current and voltage detection is achieved with voltage by an ac coupling or a heterodyne technique. The techniques can be used to extract information from analog circuits.

Campbell, Ann. N. (13170-B Central SE #188, Albuquerque, NM 87123); Anderson, Richard E. (2800 Tennessee NE, Albuquerque, NM 87110); Cole, Jr., Edward I. (2116 White Cloud NE, Albuquerque, NM 87112)

1995-01-01

48

Self-sensing magnetic levitation using a LC resonant circuit  

Microsoft Academic Search

A self-sensing magnetic levitation system utilizing a LC resonant circuit is proposed by using the characteristic that the inductance of the magnetic system is varied with respect to the air gap displacement. An external capacitor is added into the electric system to make the levitation system statically stable, which much relieves the control effort required to stabilize the magnetic levitation

Changhwan Choi

1999-01-01

49

Ferromagnetic RF integrated inductor with closed magnetic circuit structure  

Microsoft Academic Search

Closed magnetic circuit type ferromagnetic RF integrated inductors have been fabricated based on MEMS-like micro fabrication techniques. The taper etching process greatly helped to endure sufficient magnetic flux flow at the edge of the top and bottom magnetic layers. Air cores and three different sandwich type ferromagnetic inductors are also microfabricated. Measured results exhibited the quality factor Q=12, being highest

Masahiro Yamaguchi; Seok Bae; Ki Hyeon Kim; Kenji Tan; Takayuki Kusumi; Kiyoshi Yamakawa

2005-01-01

50

Testing Magnetic Air Circuit Breakers for 5Cycle Performance  

Microsoft Academic Search

Magnetic air circuit breakers are now rated 8 cycles even though they inherently demonstrate 5-cycle performance. It is therefore the responsibility of the manufacturer to test the circuit breakers so that the duty imposed by the system does not result in misapplications. To assure proper application as 5-cycle breakers the tests should show that: 1. The interrupting time does not

J. D. Wood; W. A. Carter

1958-01-01

51

Integrated circuit ac mutual inductance bridge for magnetic susceptibility measurements.  

PubMed

A versatile ac mutual inductance bridge is described which uses integrated circuit operational amplifiers (op-amps) for the measurement of magnetic susceptibilities of ferro-, ferri-, and para-magnetic samples. The circuit employs op-amps both for balancing the bridge and for detecting the differential signal from the sample coil. The response of the circuit is linear over a wide range of sample susceptibilities, and is calibrated directly in absolute units (emu) using a multiturn digital potentiometer. The sensitivity of the instrument for weak paramagnetic samples (1 g) is +/-3x10(-7) emu. PMID:18699301

Brodbeck, C M; Bukrey, R R; Hoeksema, J T

1978-09-01

52

Advanced modeling of faults in Reversible circuits  

Microsoft Academic Search

This survey provides an overview of some recent developments in the testing and design validation of reversible logic circuits Reversible circuits are of interest in ultra-low-power design and in quantum information processing. We describe the fault and error models that have been proposed for these circuits and summarize their properties. We also discuss algorithms for automatic test pattern generation, design-for-testability

Ilia Polian; John P. Hayes

2010-01-01

53

RLC Circuit with Function Generator Model  

NSDL National Science Digital Library

The RLC Circuit with Function Generator model simulates a resistor, capacitor and inductor in series with either a sinusoidal or square wave voltage source and plots the time dependence of the voltage drops across each element. Users can vary the resistance, capacitance, inductance and source frequency. The RLC Circuit with Function Generator model is a supplemental simulation for the article "Demonstrations with an LCR Circuit" by Yaakov Kraftmakher in The Physics Teacher 49(3), 168-170 (2011) and has been approved by the author and The Physics Teacher editor. The RLC Circuit model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_RlcCircuit.jar file will run the program if Java is installed.

Christian, Wolfgang

2009-10-05

54

Transistor Modeling using Advanced Circuit Simulator Technology  

Microsoft Academic Search

Abstract KRIPLANI NIKHIL, M. Transistor Modeling using advanced circuit simulator technology. (Under the direction of Michael B. Steer) The advanced MOSFET model based on the Berkeley Short Channel IGFET

NIKHIL M. KRIPLANI

55

Use of magnetic materials in excimer laser circuits  

SciTech Connect

The use of saturating magnetic materials in laser excitation discharge systems is presented. Particular attention is given to the most important parameters of magnetic materials and to the analysis of some circuits such as single and multi-stage pulse compressor and pre-pulse isolation systems. 25 refs.,5 figs.

Vannini, M.; Sze, R.; Hommeau, F.

1987-01-01

56

Suppression of Leakage Flux in Magnetic Air Circuit Breakers  

Microsoft Academic Search

The need for increased ratings of magnetic air breakers has required critical studies of and improvements in the various factors involved in the interrupting process in these devices. One important factor, the magnetic field, has been extensively explored by means of probe coils connected to integrating circuits in such a manner that instantaneous values of useful flux, leakage flux, and

A. P. Strom

1958-01-01

57

Magnetic field analysis of Lorentz motors using a novel segmented magnetic equivalent circuit method.  

PubMed

A simple and accurate method based on the magnetic equivalent circuit (MEC) model is proposed in this paper to predict magnetic flux density (MFD) distribution of the air-gap in a Lorentz motor (LM). In conventional MEC methods, the permanent magnet (PM) is treated as one common source and all branches of MEC are coupled together to become a MEC network. In our proposed method, every PM flux source is divided into three sub-sections (the outer, the middle and the inner). Thus, the MEC of LM is divided correspondingly into three independent sub-loops. As the size of the middle sub-MEC is small enough, it can be treated as an ideal MEC and solved accurately. Combining with decoupled analysis of outer and inner MECs, MFD distribution in the air-gap can be approximated by a quadratic curve, and the complex calculation of reluctances in MECs can be avoided. The segmented magnetic equivalent circuit (SMEC) method is used to analyze a LM, and its effectiveness is demonstrated by comparison with FEA, conventional MEC and experimental results. PMID:23358368

Qian, Junbing; Chen, Xuedong; Chen, Han; Zeng, Lizhan; Li, Xiaoqing

2013-01-28

58

Magnetic Field Analysis of Lorentz Motors Using a Novel Segmented Magnetic Equivalent Circuit Method  

PubMed Central

A simple and accurate method based on the magnetic equivalent circuit (MEC) model is proposed in this paper to predict magnetic flux density (MFD) distribution of the air-gap in a Lorentz motor (LM). In conventional MEC methods, the permanent magnet (PM) is treated as one common source and all branches of MEC are coupled together to become a MEC network. In our proposed method, every PM flux source is divided into three sub-sections (the outer, the middle and the inner). Thus, the MEC of LM is divided correspondingly into three independent sub-loops. As the size of the middle sub-MEC is small enough, it can be treated as an ideal MEC and solved accurately. Combining with decoupled analysis of outer and inner MECs, MFD distribution in the air-gap can be approximated by a quadratic curve, and the complex calculation of reluctances in MECs can be avoided. The segmented magnetic equivalent circuit (SMEC) method is used to analyze a LM, and its effectiveness is demonstrated by comparison with FEA, conventional MEC and experimental results.

Qian, Junbing; Chen, Xuedong; Chen, Han; Zeng, Lizhan; Li, Xiaoqing

2013-01-01

59

Frequency-Dependent Coupled Field-Circuit Modeling of Armored Power Cables Using Finite Elements  

Microsoft Academic Search

This paper proposes a frequency-dependent electromagnetic model for armored power cables using Coupled circuit-field method. The model parameters were obtained by conducting a series of coupled field-circuit studies at different frequencies. The cable capacitance matrix iscalculated usinganelectrostaticFEanalysis.Thefrequencyresponse ofthecablewasobtainedbycouplingthe cableFEdomain model and external electric circuits. This technique allows the physical representation of the nonlinear magnetization behavior of the cable shell as

Nagy Y. Abed; Osama A. Mohammed

2011-01-01

60

Qualitative Circuit Models in Failure Analysis Reasoning  

Microsoft Academic Search

The engineering task of failure analysis involves reasoning about the behaviour of a system using appropriate models of system components and structure. This paper describes methods of qualitatively modelling electrical circuits that support the requirements for certain combinatorially demanding forms of failure analysis. Minimal models, based on zero-order quiescent conditions, are examined and a particular formulation, known as CIRQ, is

M. H. Lee

1999-01-01

61

Electric vehicle charger with printed circuit board magnetic components  

Microsoft Academic Search

An 800 Watt portable battery charger for electric vehicles is built using a single four-layer printed circuit board for interconnection all of the power components and to form the magnetic component windings which comprise the EMI filter, a high power factor boost rectifier and a series resonant inverter. Low profile planar E-cores are inserted through slots in the PCB to

C. P. Henze

2000-01-01

62

A study on the permanent magnet overhang effect in permanent magnetic actuator using 3-dimension equivalent magnetic circuit network method  

Microsoft Academic Search

This paper presents the analysis of the permanent magnet overhang effect for permanent magnetic actuator. Generally, The overhang is often used to increase the force density in permanent magnet machineries. The overhang is especially profitable to reduce the volume after increasing the force density per volume when using the overhang effect of the permanent magnet. Therefore, 3D equivalent magnetic circuit

Ho Kwon; S.-Y. Kwon; Ju Lee; Seung-kil Choi; Soo-Hyun Baek

2003-01-01

63

Modeling metastability in circuit design  

US Patent & Trademark Office Database

A computer program (100, 200) encoded in a computer-programmable medium, and for causing a computer to perform circuit design. The code causes the computer to perform a set of steps. The steps comprise describing a first set of circuitry and describing a second set of circuitry. The steps also comprise describing a digital signal for passing from the first set of circuitry to the second set of circuitry and detecting (230) transitions of the digital signal with respect to a timing constraint (240) of at least a portion of the second set of circuitry. Lastly, the steps comprise, responsive to detecting metastability with respect to timing of a transition of the digital signal relative to the timing constraint of at least a portion of the second set of circuitry, forcing (160) the digital signal to a random value and passing the random value to the second set of circuitry.

2006-11-21

64

Macro-model of Spin-Transfer Torque based Magnetic Tunnel Junction device for hybrid Magnetic-CMOS design  

Microsoft Academic Search

The development of hybrid magnetic-CMOS circuits such as MRAM (magnetic RAM) and magnetic logic circuit requires efficient simulation models for the magnetic devices. A macro-model of magnetic tunnel junction (MTJ) is presented in this paper. This device is the most commonly used magnetic components in CMOS circuits. This model is based on spin-transfer torque (STT) writing approach. This very promising

W. Zhao; E. Belhaire; Q. Mistral; C. Chapped; V. Javerliac; B. Dieny; E. Nicolle

2006-01-01

65

Equivalent circuit model of resistive IC sensors derived with the box integration method  

Microsoft Academic Search

We present an automatic method to produce compact equivalent circuit models of spatially inhomogeneous resistors. Local variations in space of the resistivity due to physical interactions such as magnetic fields or mechanical stress are automatically included. The equivalent circuit model is computed using symbolic algebra, such that the functional relation between the resistivity and the fields interacting with it is

Christoph Maier; Markus Emmenegger; Stefano Taschini; Henry Baltes; Jan G. Korvink

1999-01-01

66

Circuit and Coil Design for In-Vitro Magnetic Neural Stimulation Systems  

Microsoft Academic Search

Magnetic stimulation of neural tissue is an attractive technology because neural excitation may be affected without requiring implantation of electrodes. Pulsed discharge circuits are typically implemented for clinical magnetic stimulation systems. However, pulsed discharge systems can confound in-vitro experimentation. As an alternative to pulsed discharge circuits, we present a circuit to deliver asymmetric current pulses for generation of the magnetic

Eric Basham; Zhi Yang; Wentai Liu

2009-01-01

67

Nonlinear varying-network magnetic circuit analysis of doubly salient permanent-magnet motors  

SciTech Connect

During the past decade, switched reluctance (SR) motors have received much research attention. They offer the advantages of simple structure, fault tolerance, and mechanical robustness, leading to attractiveness for industrial and electrical vehicle (EV) applications. In this paper, a nonlinear varying-network magnetic circuit (VNMC) modeling method is developed for doubly salient permanent-magnet (DSPM) motors. The method is used to analyze the static characteristics of DSPM motors by specific permeance calculations, in which the interaction between the permanent-magnet field and the armature current field, as well as magnetic saturation, are taken into account. Two newly proposed DSPM motors (12/8-pole and 6/4-pole) are used as examples. There is good agreement between the results of the nonlinear VNMC modeling method and finite-element analysis. Moreover, the nonlinear VNMC method offers the advantage of calculating, effectively and efficiently, the static characteristics of DSPM motors having different dimensions, parameters, and conditions. Finally, the proposed method is verified by experimental testing of a 6/4-pole prototype.

Cheng, M.; Chau, K.T.; Chan, C.C.; Zhou, E.; Huang, X.

2000-01-01

68

New method of modeling electronic circuits coupled with 3D electromagnetic finite element models  

NASA Astrophysics Data System (ADS)

New zero-dimensional or scalar electromagnetic finite elements taht have the time integral of electric scalar potential as their nodal variable are presented. There are three zero-dimensional element types, representing resistors, capacitors, and inductors. These elements can be easily combined with two- or three-dimensional elements, with three components of magnetic vector potential and the time integral of electric scalar potential as nodal variables. Constant current sources are directly modeled by inhomogeneous Neumann excitations, and constant voltage sources are modeled by use of Norton's theorem. By the addition of dependent current and voltage sources, electronic circuits can be modeled. Example finite-element analyses include an R-L circuit, a transistor circuit driving a wire loop modeled with three-dimensional finite elements, and a circuit impedance on the secondary of a saturable three-dimensional transformer model.

Brauer, J. R.; MacNeal, B. E.; Larkin, L. A.; Overbye, V. D.

1991-09-01

69

Modeling and design of an electromagnetic vibration energy harvester and its dedicated energy extraction circuit  

Microsoft Academic Search

This work investigates the design of an electromagnetic generator including its energy extraction and conditioning circuit. The normalized model of an electromagnetic generator points out three dimensionless parameters, characteristic of the generator. The power harvested with the SMFE (Synchronized Magnetic Flux Extraction) circuit is theoretically calculated and compared to the power extracted with a conventional approach. Optimal parameters orders of

Emmanuelle Arroyo; Adrien Badel; Fabien Formosa

2012-01-01

70

Adult neurogenesis. From circuits to models.  

PubMed

Our understanding of the hippocampus as a memory-encoding device is greatly helped by our knowledge of neuronal circuits and their plasticity. The trisynaptic hippocampal circuit carrying afferent input from the entorhinal cortex, controlled by a network of inhibitory interneurons and supplemented by modulatory subcortical inputs forms a platform for multiple forms of synaptic plastic mechanisms. Long-term potentiation of synaptic transmission in its various forms is an outstanding example of hippocampal ability to adapt to past neuronal activity. Adult neurogenesis is a profound plastic mechanism incorporating structural and functional changes that were previously thought to be present only in developing neural systems. These powerful forms of plasticity can mask experimental results by compensating for experimentally induced changes in the neurons or circuits. Circuit lesions have been one of the most common techniques in scientific investigations of the hippocampus. Although the effects of such lesions can be quite revealing and ground-breaking, in many cases the results are masked by compensatory mechanisms producing misleading results. This review will highlight such mechanisms and argue that the experimental results, in spite of their shortcomings, can be better understood when viewed in light of our knowledge of the neuronal circuitry, and with guidance by conceptual and computational models. Studies demonstrating a role of neurogenesis in pattern separation and memory interference are a good example of fruitful interaction between modeling and experimental approaches. PMID:21893104

Wojtowicz, J Martin

2011-08-12

71

Modeling digital circuits for troubleshooting - An overview  

NASA Astrophysics Data System (ADS)

An overview of a model-based troubleshooting program that incorporates a domain-independent diagnosis engine based on de Kleer and Williams' (1987) GDE is presented. The primary input to the program is a model of a digital circuit that is a network of components and connections. Each component has a description of its dynamic time-dependent behavior and each connection transmits signals between components. The secondary input to the program is a description of the stimuli presented to the circuit and observations of its actual responses. The model uses those stimuli to predict what the outcomes of observations ought to be. When discrepancies are discovered, the program produces a list of components that could be responsible for the discrepancies, ranked by their relative likelihood. The program interactively suggests what observations should be made next in order to discriminate among these possibilities, then uses any new observations to incrementally focus on the correct diagnosis.

Hamscher, Walter

72

Calculation and Analysis of Dynamic Characteristics of Multilink Permanent Magnetic Actuator in Vacuum Circuit Breaker  

NASA Astrophysics Data System (ADS)

The dynamic characteristics are the key issues in the optimum design of a permanent magnetic actuator (PMA). A new approach to forecast the dynamic characteristics of the multilink PMA is proposed. By carrying out further developments of ADAMS and ANSOFT, a mathematic calculation model describing the coupling of mechanical movement, electric circuit and magnetic field considering eddy current effect, is constructed. With this model, the dynamic characteristics of the multilink PMA are calculated and compared with the experimental results. Factors that affect the opening time of the multilink PMA are analyzed with the model as well. The method is capable of providing a reference for the design of the PMA.

Liu, Yingyi; Yuan, Haiwen; Zhang, Qingjie; Chen, Degui; Yuan, Haibin

73

A Compact Circuit Model of Five-Port Transformer Balun for CMOS RF Integrated Circuits  

NASA Astrophysics Data System (ADS)

A compact circuit model for five-port on-chip transformer balun is presented. Compared to the conventional model, the proposed model is simpler without any accuracy degradation and ensures faster convergence time, which in turn enables flexible RF circuit design optimization. The validity of the proposed model is confirmed through extensive EM simulations and measurements.

Chang, Shinil; Shin, Hyunchol

74

A Compact Circuit Model of Five-Port Transformer Balun for CMOS RF Integrated Circuits  

Microsoft Academic Search

A compact circuit model for five-port on-chip transformer balun is presented. Compared to the conventional model, the proposed model is simpler without any accuracy degradation and ensures faster convergence time, which in turn enables flexible RF circuit design optimization. The validity of the proposed model is confirmed through extensive EM simulations and measurements.

Shinil Chang; Hyunchol Shin

2008-01-01

75

Circuit Model of Battery Recharging by Volume Conduction  

Microsoft Academic Search

Many current implantable devices require large capacity batteries implanted in the body. In this paper we present a new approach of transcutaneous battery recharging by volume conduction and its circuit model. We also analyze the current transmitting efficiency and rechargeable prerequisite of transcutaneous battery recharging by applying this circuit model. The experiments prove the legitimacy of the circuit model.

Zhide Tang; R. J. Sclabassi; Caixin Sun; Jun Zhao; S. A. Hackworth; Mingui Sun

2006-01-01

76

Equivalent circuit modeling of interconnects from time-domain measurements  

Microsoft Academic Search

A technique for the equivalent circuit modeling of single and coupled uniform and nonuniform interconnects, including discontinuities such as bends and junctions in high-speed circuits and packages, is presented. The circuit models are extracted from time-domain reflection and transmission measurement (TDR\\/T). The SPICE simulated results for the extracted circuit models for typical single and coupled structures are compared with the

Jyh-Ming Jong; Bozidar Janko; Vijai Tripathi

1993-01-01

77

Modeling A circuit switched multiprocessor interconnect  

NASA Astrophysics Data System (ADS)

This study began as an attempt to understand discrepancies between Patel's classic model of a circuit-switched interconnection network and simulations as part of the MIT ALEWIFE Multiprocessor project. After a careful analysis of Patel's model, we developed a model with fewer approximations that produced results generally closer to detailed simulation. The major source of inaccuracy in Patel's model is the unit-request approximation, which treats a t-cycle request as t l-cycle requests producing significant inaccuracies for networks with many switching levels and for small packet sizes. Our model followed the behavior of the network more closely, explicitly modeling the effects of switch size, network depth, packet size and memory latency, thereby alleviating some inaccuracies in Patel's model. However, despite the slightly lower accuracy of Patel's model, we believe that its simplicity makes it the practical choice for most applications. Thus, our main contribution was to understand the causes of inaccuracies in both models, allowing us to predict the quality of the estimations they yielded. Another research result is validating a complicated simulator using relatively simple models, not a common use for a model. We found that some of the original discrepancies between Patel's model and the simulator were due to hidden inconsistancies between parameters used by the model and those used by the simulator, and that others were due to bugs in the simulator code.

Nussbaum, Daniel; Vuong-Adlerberg, Ingmar; Agarwal, Anant

1989-10-01

78

Large signal klystron simulations using a curnow circuit model  

Microsoft Academic Search

Summary form only given. Simulation codes used for large signal analysis of coupled cavity traveling wave tubes commonly use a lumped element model of the traveling wave circuit due to Curnow. When the circuit unit cells are not connected to one another, we show that for suitable choices of lumped element circuit parameters, a Curnow cell can be used to

D. Chernin; T. Antonsen; B. Levush

2006-01-01

79

The Development, Design, and Performance of Magnetic-Type Power Circuit Breakers  

Microsoft Academic Search

Power circuit breakers for voltage services of 2,300 volts and above use either of two basic principles to complete circuit interruption. The more familiar types, oil breakers or compressed air breakers, complete their operation by maintaining a low resistance arc until the final current zero where interruption is completed. Magnetic air circuit breakers establish a high resistance arc prior to

L. J. Linde; B. W. Wyman

1946-01-01

80

Model magnet studies  

Microsoft Academic Search

A design, construction, and testing program for model magnets is underway at Fermilab to evaluate alternatives in the development of small aperture magnets. The most thoroughly developed of these programs utilizes a set of model magnets based on the Tevatron quadrupoles and dipoles as a standard. These 7.6cm aperture model magnets, approximately 64cm long, have construction or material changes which

A. D. McInturff; J. Carson; N. Engler; H. Fisk; R. Hanft; R. Lundy; P. Mantsch; T. Nicol; R. Niemann; E. Schmidt; A. Szymulanski

1985-01-01

81

Implementation of Mason's Model on Circuit Analysis Programs  

Microsoft Academic Search

Abstruct-The Redwood bersion of Mason's model has been rearranged to provide a topology suitable for computer modeling. The modified circuit uses a hybrid representation of the electromechanical transformer, an accurate approximation of the negative capacitor C,, and modified coupling from the transformer to the acoustic transmission line. This arrangement provides a model that is applicable to circuit simulation packages. Model

S. A. Morris; C. G. Hutchens

1986-01-01

82

Optimization of the magnetic circuit in the MFL inspection system for storage-tank floors  

Microsoft Academic Search

Magnetization is the key to inspection of a tank floor via the magnetic-flux-leakage (MFL) technique. In order to optimize\\u000a the magnetic circuit of the MFL detector and obtain the best detection effects, the influences of the magnet size on the floor\\u000a magnetization condition, the gap magnetic flux density, and the magnetic force were studied with the help of the finite

Xiao-chun Song; Song-ling Huang; Wei Zhao

2007-01-01

83

The Design of a RapidDischarge Varistor System for the MICE Magnet Circuits  

SciTech Connect

The need for a magnet circuit discharge system, in order to protect the magnet HTS leads during a power failure, has been discussed in recent MICE reports [1], [2]. In order to rapidly discharge a magnet, one has to put enough resistance across the lead. The resistance in this case is varistor that is put across the magnet in the event of a power outage. The resistance consists of several diodes, which act as constant voltage resistors and the resistance of the cables connecting the magnets in the circuit to each other and to the power supply. In order for the rapid discharge system to work without quenching the magnets, the voltage across the magnets must be low enough so that the diodes in the quench protection circuit don't fire and cause the magnet current to bypass the superconducting coils. It is proposed that six rapid discharge varistors be installed across the three magnet circuits the power the tracker solenoids, which are connected in series. The focusing magnets, which are also connected in series would have three varistors (one for each magnet). The coupling magnets would have a varistor for each magnet. The peak voltage that is allowed per varistor depends on the number of quench protection diodes that make up the quench protection circuit for each magnet coil circuit. It is proposed that the varistors be water cooled as the magnet circuits are being discharged through them. The water cooling circuit can be supplied with tap water. The tap water flows only when the varistor temperature reaches a temperature of 45 C.

Green, Michael A.

2008-07-23

84

Computation of magnetic suspension of maglev systems using dynamic circuit theory  

SciTech Connect

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper. 15 refs., 7 figs., 1 tab.

He, J.L.; Rote, D.M.; Coffey, H.T.

1991-01-01

85

Respiratory circuits: development, function and models.  

PubMed

Breathing is a rhythmic motor behavior generated and controlled by hindbrain neuronal networks. Respiratory motor output arises from two distinct, but functionally interacting, rhythmogenic networks: the pre-Bötzinger complex (preBötC) and the retrotrapezoïd nucleus/parafacial respiratory group (RTN/pFRG). This review outlines recent advances in delineating the genetic specification of the neuronal constituents of these two rhythmogenic networks, their respective roles in respiratory function and how they interact to constitute a functional respiratory circuit ensemble. The often lethal consequences of disruption to these networks found in naturally occurring developmental disorders, transgenic animals, and highly specific lesion studies are described. In addition, we discuss how recent computational models enhance our understanding of how respiratory networks generate and regulate respiratory behavior. PMID:22281058

Mellen, Nicholas M; Thoby-Brisson, Muriel

2012-01-24

86

Circuit and Numerical Modeling of Electrostatic Discharge Generators  

Microsoft Academic Search

This paper provides two accurate and efficient models of electrostatic discharge generators which permit to reproduce the discharge current in the contact mode, taking into account the load effect. The first model is based on a circuit approach and is suitable to be implemented in any commercial circuit simulator. The second model is based on the numerical solution of the

Spartaco Caniggia; Francescaromana Maradei

2006-01-01

87

Running Head: CONNECTIVITY MODELS FROM CIRCUIT THEORY Title: USING CIRCUIT THEORY TO MODEL CONNECTIVITY IN ECOLOGY, EVOLUTION, AND CONSERVATION  

Microsoft Academic Search

Connectivity among populations and habitats is important for a wide range of ecological processes. Understanding, preserving, and restoring connectivity in complex landscapes requires connectivity models and metrics that are reliable, efficient, and process- based. We introduce a new class of ecological connectivity models based in electrical circuit theory. Although they have been applied in other disciplines, circuit-theoretic connectivity models are

BRAD H. MCRAE; BRETT G. DICKSON; TIMOTHY H. KEITT; VIRAL B. SHAH

88

Performance of the Superconducting Corrector Magnet Circuits during the Commissioning of the LHC  

Microsoft Academic Search

The LHC is a complex machine requiring more than 7400 superconducting corrector magnets distributed along a circumference of 26.7 km. These magnets are powered in 1446 different electrical circuits at currents ranging from 60 A up to 600 A. Among the corrector circuits the 600 A corrector magnets form the most diverse and differentiated group. All together, about 60000 high current

W Venturini-Delsolaro; V. Baggiolini; A. Ballarino; B. Bellesia; Frederick Bordry; A. Cantone; M. P. Casas Lino; A Castaneda Serra; C Castillo Trello; N Catalan-Lasheras; Z Charifoulline; C Charrondiere; K Dahlerup-Petersen; G D'Angelo; R Denz; S Fehér; R Flora; M Gruwé; V Kain; M Karppinen; B Khomenko; G Kirby; A MacPherson; A Marqueta Barbero; K H Mess; M Modena; R Mompo; V Montabonnet; S le Naour; D Nisbet; V Parma; M Pojer; L Ponce; A Raimondo; S Redaelli; V Remondino; H Reymond; G de Rijk; A Rijllart; I Romera Ramirez; R. Schmidt; S Sanfilippo; K Schirm; R Schmidt; A Siemko; M Solfaroli Camillocci; Y Thurel; H Thiesen; A Vergara Fernandez; A Verweij; R Wolf; M Zerlauth

2008-01-01

89

Short-Circuit Modeling of a Wind Power Plant: Preprint  

SciTech Connect

This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. The short-circuit behavior will be presented. Both the simplified models and detailed models are used in the simulations and both symmetrical faults and unsymmetrical faults are discussed.

Muljadi, E.; Gevorgian, V.

2011-03-01

90

Evaluating Circuit Reliability Under Probabilistic Gate-Level Fault Models  

Microsoft Academic Search

Circuit reliability is an increasingly important design con- sideration for modern logic circuits. To this end, our work focuses on the evaluation of circuit reliability under pro- babilistic gate-level fault models that can capture both soft errors, e.g., radiation-related, and spatially-uniform man- ufacturing defects. This basic task can, in principle, be used (i) by synthesis procedures to select more reliable

Ketan N. Patel; Igor L. Markov; John P. Hayes

91

CMOS Interface Circuits for Spin Tunneling Junction Based Magnetic Random Access Memories  

SciTech Connect

Magneto resistive memories (MRAM) are non-volatile memories which use magnetic instead of electrical structures to store data. These memories, apart from being non-volatile, offer a possibility to achieve densities better than DRAMs and speeds faster than SRAMs. MRAMs could potentially replace all computer memory RAM technologies in use today, leading to future applications like instan-on computers and longer battery life for pervasive devices. Such rapid development was made possible due to the recent discovery of large magnetoresistance in Spin tunneling junction devices. Spin tunneling junctions (STJ) are composite structures consisting of a thin insulating layer sandwiched between two magnetic layers. This thesis research is targeted towards these spin tunneling junction based Magnetic memories. In any memory, some kind of an interface circuit is needed to read the logic states. In this thesis, four such circuits are proposed and designed for Magnetic memories (MRAM). These circuits interface to the Spin tunneling junctions and act as sense amplifiers to read their magnetic states. The physical structure and functional characteristics of these circuits are discussed in this thesis. Mismatch effects on the circuits and proper design techniques are also presented. To demonstrate the functionality of these interface structures, test circuits were designed and fabricated in TSMC 0.35{micro} CMOS process. Also circuits to characterize the process mismatches were fabricated and tested. These results were then used in Matlab programs to aid in design process and to predict interface circuit's yields.

Ganesh Saripalli

2002-12-31

92

Performance of the Superconducting Corrector Magnet Circuits during the Commissioning of the LHC  

SciTech Connect

The LHC is a complex machine requiring more than 7400 superconducting corrector magnets distributed along a circumference of 26.7 km. These magnets are powered in 1446 different electrical circuits at currents ranging from 60 A up to 600 A. Among the corrector circuits the 600 A corrector magnets form the most diverse and differentiated group. All together, about 60000 high current connections had to be made. A fault in a circuit or one of the superconducting connections would have severe consequences for the accelerator operation. All magnets are wound from various types of Nb-Ti superconducting strands, and many contain parallel protection resistors to by-pass the current still flowing in the other magnets of the same circuit when they quench. In this paper the performance of these magnet circuits is presented, focusing on the quench behavior of the magnets. Quench detection and the performance of the electrical interconnects will be dealt with. The results as measured on the entire circuits are compared to the test results obtained at the reception of the individual magnets.

Venturini Delsolaro, W.; Baggiolini, V.; Ballarino, A.; Bellesia, B.; Bordry, F.; Cantone, A.; Casas Lino, M.P.; CastilloTrello, C.; Catalan-Lasheras, N.; Charifoulline, Zinour; Charrondiere, C.; /CERN /Madrid, CIEMAT /Fermilab

2008-06-25

93

Modeling of Integrated Circuit Effectiveness (Mice).  

National Technical Information Service (NTIS)

A Stress Survival Matrix Test (SSMT) and Physical Effects Analysis (PEA) program was conducted on a type of monolithic silicon integrated circuit from two vendors. The purposes of the program were to identify the basic reliability characteristics of integ...

B. F. Tiger D. I. Troxel

1967-01-01

94

A discussion of yield modeling with defect clustering, circuit repair, and circuit redundancy  

Microsoft Academic Search

The mathematical foundation of common integrated--circuit yield models based on the assumption that the yield is dominated by random point defects is discussed. Various mathematical models which are commonly used to account for defect clustering are given a physical interpretation and are compared mathematically and graphically. A yield model applicable when the repair of some defects in a chip is

T. L. Michalka; R. C. Varshney; J. D. Meindl

1990-01-01

95

Design of Power Electronics Driven PMSM with Constant Torque by Special Magnetic Circuit and Permanent Magnet Configuration  

Microsoft Academic Search

Special and high efficiency variable speed drives use permanent magnet synchronous motors (PMSM) and power electronics. New dispositions for PMSM with regard to a special magnetic circuit design and new shapes of permanent magnet configurations are investigated. In order to obtain a better rotation performance and to reduce the torque ripple we propose the power electronics current control in support

W. Czernin; F. Asehenbrenner; H. Weiss

2006-01-01

96

Noise Source Lumped Circuit Modeling and Identification for Power Converters  

Microsoft Academic Search

In this paper, a general lumped circuit modeling method is proposed to describe the conducted electromagnetic interference (EMI) coupling mechanism for the switching power converters. The EMI characteristics of the converters can be analytically deduced from a circuit theoretical viewpoint. The shunt and series impedance insertion method is introduced to identify the differential-mode (DM) and common-mode (CM) noise impedances and

Jin Meng; Weiming Ma; Qijun Pan; Zhihua Zhao; Lei Zhang

2006-01-01

97

Computation of Magnetic Suspension of Maglev Systems Using Dynamic Circuit Theory.  

National Technical Information Service (NTIS)

Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical ...

J. L. He D. M. Rote H. T. Coffey

1992-01-01

98

The Duality between Interlinked Electric and Magnetic Circuits and the Formation of Transformer Equivalent Circuits  

Microsoft Academic Search

When making calculations on a circuit, containing both electric impedances and transformers, it is frequently desirable to consider the transformers removed and the constraints they impose replaced by a rearrangement of the impedances connected to their terminals. Such \\

E Colin Cherry

1949-01-01

99

Wide-band corona circuit model for transient simulations  

SciTech Connect

Corona in overhead transmission lines is a highly nonlinear and non-deterministic phenomenon. Circuit models have been developed to represent its behavior, but the response of these models is usually limited to a narrow set of frequencies. The circuit model presented in this paper achieves a much wider frequency response than previous models: (1) by matching more closely the topology of the circuit, and (2) by using a second-order circuit response to match the high-order dynamic response of the phenomenon. The resulting model is valid for a wide range of frequencies and is able to represent waveshapes from switching to lightning surges. The model is applied to the EMTP program and simulations of q-v measurements and travelling surges are presented.

Marti, J.R.; Castellanos, F.; Santiago, N. [Univ. of British Columbia, Vancouver, British Columbia (Canada)

1995-05-01

100

Performance of the Main Dipole Magnet Circuits of the LHC during Commissioning  

Microsoft Academic Search

During hardware commissioning of the Large Hadron Collider (LHC), 8 main dipole circuits are tested at 1.9 K and up to their nominal current. Each dipole circuit contains 154 magnets of 15 m length, and has a total stored energy of up to 1.3 GJ. All magnets are wound from Nb-Ti superconducting Rutherford cables, and contain heaters to quickly force

A. Verweij; V. Baggiolini; A. Ballarino; B. Bellesia; Frederick Bordry; A. Cantone; M. Casas Lino; A. Castaneda Serra; C. Castillo Trello; N Catalan-Lasheras; Z. Charifoulline; G. Coelingh; K. Dahlerup-Petersen; G. D'Angelo; R. Denz; S. Feher; R. Flora; M. Gruwe; V. Kain; B. Khomenko; G. Kirby; A. MacPherson; A. Marqueta Barbero; K.-H. Mess; M. Modena; R. Mompo; V. Montabonnet; S le Naour; D Nisbet; V Parma; M Pojer; L Ponce; A Raimondo; S Redaelli; H Reymond; D Richter; G de Rijk; A Rijllart; I Romera Ramirez; R Saban; S Sanfilippo; R Schmidt; A Siemko; M Solfaroli Camillocci; Y Thurel; H Thiessen; W Venturini-Delsolaro; A Vergara Fernandez; R Wolf; M Zerlauth

2008-01-01

101

Models of magnetism  

NSDL National Science Digital Library

This study investigates the mental models that people construct about magnetic phenomena. The project involved students, physics teachers, engineers, and practitioners. The researchers propose five models following a progression from simple description to a field model. Contains 28 references.

Borges, A. T.; Gilbert, John; Tecnico, Colegio

2006-05-23

102

Modeling buffer layer IGBTs for circuit simulation  

Microsoft Academic Search

The dynamic behavior of commercially available buffer layer IGBTs is described. It is shown that buffer layer IGBTs become much faster at high voltages than nonbuffer layer IGBTs with similar low voltage characteristics. Because the fall times specified in manufacturers' data sheets do not reflect the voltage dependence of switching speed, a new method of selecting devices for different circuit

1995-01-01

103

A Magnet Spring Model  

ERIC Educational Resources Information Center

The paper discusses an elementary spring model representing the motion of a magnet suspended from the ceiling at one end of a vertical spring which is held directly above a second magnet fixed on the floor. There are two cases depending upon the north-south pole orientation of the two magnets. The attraction or repelling force induced by the…

Fay, T. H.; Mead, L.

2006-01-01

104

Partitioning and Redundancy Model for Wafer-Scale Integrated Circuits.  

National Technical Information Service (NTIS)

A general, architecture independent model to calculate the required amount of redundancy and the necessary degree of partitioning of the circuit to achieve a maximum efficiency are presented. In wafer scale integration, a certain amount of redundancy is r...

M. F. Beusekamp

1991-01-01

105

Circuit Modeling of Injection Probes for Bulk Current Injection  

Microsoft Academic Search

In this paper, two procedures are developed for lumped-parameter circuit modeling of injection probes for bulk current injection (BCI). Both procedures are based on frequency-domain scattering-parameter measurements, and refer to a clamped wiring composed of a single-ended interconnection. One procedure exploits a black-box approach, requires a calibration fixture, and is suited for practical implementation. The other is based on circuit

Flavia Grassi; Filippo Marliani; Sergio A. Pignari

2007-01-01

106

A dynamic circuit theory of the repulsive magnetic levitation system  

Microsoft Academic Search

A generalized machine theory formulation is derived for the repulsive magnetic levitation system consisting of flat superconducting magnets interacting with flat finite width strip conducting guideways. Experimental verifications are presented.

Boon-Teck Ooi

1977-01-01

107

Modelling of a car starter with permanent magnet commutator motor  

Microsoft Academic Search

Purpose – The purpose of this paper is to present a developed modelling method of a car starter with permanent magnet commutator motor. Design\\/methodology\\/approach – Mathematical model, algorithm and computational program of electrical and mechanical quantities transients in the system: battery – car starter with permanent magnet commutator motor and planetary gear – combustion engine were developed. Circuit-field method was

M. Ciurys; I. Dudzikowski; D. Gierak

2009-01-01

108

Modeling electromagnetic emission of integrated circuits for system analysis  

Microsoft Academic Search

In this contribution a new methodology for modeling elec- tromagnetic emission of integrated circuits in system anal- ysis is shown. By using a physical model based on a multi- pole expansion, the emitted fields can be well approximated in the space outside a component. This allows a conve- nient representation with a low number of model parame- ters which can

P. Kralicek; Werner John; Heyno Garbe

2001-01-01

109

MOS transistor modeling for RF integrated circuit design  

Microsoft Academic Search

The design of radio-frequency (RF) integrated circuits in deep-submicron CMOS processes requires accurate and scalable compact models of the MOS transistor that are valid in the GHz frequency range and even beyond. Unfortunately, the currently available compact models give inaccurate results if they are not modified adequately. This paper presents the basis of the modeling of the MOS transistor for

Christian Enz

2000-01-01

110

MODELLING AND IMPLEMENTATION ISSUES IN CIRCUIT AND NETWORK PLANNING TOOLS  

Microsoft Academic Search

This thesis consists of studies of practical, industrial use of mathematical models and algorithms. Its focus is on modelling and implementation issues of planning tools on the engineering domain. Using a circuit design and a network planning tool as concrete examples the thesis analyses the practical issues of the development and maintenance of such systems and, especially, how models and

Jukka K. Nurminen

111

Estimating Preferences of Circuit Judges: A Model of Consensus Voting  

Microsoft Academic Search

This paper develops a consensus voting model for estimating preferences of federal circuit court judges. Unlike standard ideal point models, which assume that judges vote sincerely for their preferred outcomes, the consensus model accounts for the norm of consensus in the courts of appeals by including a cost of dissent in the judicial utility function. A test of the consensus

Joshua B. Fischman

2011-01-01

112

Distributed B-spline electrothermal models of thyristors proposed for circuit simulation of power electronics  

Microsoft Academic Search

A B-spline based electrothermal model for thyristors is proposed for circuit simulations and is demonstrated for gate-triggered resistive circuits by comparison with PISCES simulation results. The model topology for small area thyristors consists of an electrical device circuit model and a thermal circuit model which are coupled together to establish the interaction between the electrical and thermal responses. A distributed

Chih-Ju Hung; Patrick Roblin; Siraj Akhtar

2001-01-01

113

SF6 Magnetic-Puffer Circuit Breaker for 34.5 kV, 1500 MVA  

Microsoft Academic Search

A circuit breaker of a new type has been developed as the removable breaker element for metal-clad switchgear for 23\\/34.5 kV service. It is a single pressure, dead-tank SF6 circuit breaker which employs magnetic driving action produced by the fault current to drive the gas through the arc to interrupt it. Complete development tests have been performed, as required by

Russell Frink

1968-01-01

114

A hybrid magnetic/complementary metal oxide semiconductor process design kit for the design of low-power non-volatile logic circuits  

NASA Astrophysics Data System (ADS)

Since the advent of the MOS transistor, the performance of microelectronic circuits has followed Moore's law, stating that their speed and density would double every 18 months. Today, this trend tends to get out of breath: the continuously decreasing size of devices and increasing operation frequency result in power consumption and heating issues. Among the solutions investigated to circumvent these limitations, the use of non-volatile devices appears particularly promising. It allows easing, for example, the power gating technique, which consists in cutting-off the power supply of inactive blocks without losing information, drastically reducing the standby power consumption. In this approach, the advantages of magnetic tunnel junctions (MTJs) compared with other non-volatile devices allow one to design hybrid CMOS/magnetic circuits with high performance and new functionalities. Designing such circuits requires integrating MTJs in standard microelectronics design suites. This is performed by means of a process design kit (PDK) for the hybrid CMOS/magnetic technology. We present here a full magnetic PDK, which contains a compact model of the MTJ for electrical simulation, technology files for layout and physical verifications, and standard cells for the design of complex logic circuits and which is compatible with standard design suites. This PDK allows designers to accurately and comfortably design high-performance hybrid CMOS/magnetic logic circuits in the same way as standard CMOS circuits.

Di Pendina, G.; Prenat, G.; Dieny, B.; Torki, K.

2012-04-01

115

Impact of radial external magnetic field on plasma deformation during contact opening in SF6 circuit breakers  

NASA Astrophysics Data System (ADS)

A three-dimensional (3D) transient model is developed to investigate plasma current deformation driven by internal and external magnetic fields and their influences on arc stability in a circuit breaker. The 3D distribution of electric current density is obtained by solving the current continuity equation along with the generalized Ohm's law in the presence of an external magnetic field, while the magnetic field induced by the current flowing through the arc column is calculated by the magnetic vector potential equation. The applied external field imposes a rotational electromagnetic force on the arc and influences the plasma current deformation, which is discussed in this paper. In SF6 circuit breakers when gas interacts with the arc column, the fundamental equations such as Ampere's law, Ohm's law, turbulence model, transport equations of mass, momentum, and energy of plasma flow have to be coupled for analysing the phenomenon. The coupled interactions between the arc and the plasma flow are described within the framework of magnetohydrodynamic equations in conjunction with a K-? turbulence model. Simulations are focused on sausage and kink instabilities in the plasma (these phenomena are related to the electromagnetic field distribution and define the plasma deformations). The 3D simulation reveals the relation between plasma current deformation and instability phenomena, which affects the arc stability during the operation. Plasma current deformation is a consequence of coupling between electromagnetic forces (resulting from internal and radial external magnetic fields) and the plasma flow that are described in the simulations.

Abbasi, V.; Gholami, A.; Niayesh, K.

2012-10-01

116

Circuit Model for Gun Driven Spheromaks  

SciTech Connect

In this note we derive circuit equations for sustained spheromaks, in the phase after a spheromak is detached from the gun and sustained in a flux conserver. The impedance of the spheromak during the formation and ''bubble burst'' phase has been discussed by Barnes et. al. We assume here that the spheromak is formed and helicity is being delivered to it from the gun, currents are above the threshold current, and the {lambda}-gradients are outward ({lambda} decreasing inward). We follow an open field line that begins and ends at the gun electrodes, encircling the closed flux surfaces of the spheromak, and apply power and helicity balance equations for this gun-driven system. In addition to these equations one will need to know the initial conditions (currents, stored energies) after the ''bubble burst'' in order to project forward in time.

Thomassen, K I

2000-07-14

117

Quantum Magnetism Analysis Model  

NSDL National Science Digital Library

The Quantum Magnetism Analysis Model was created to help students as well as researchers who are studying magnetism. It provides a very simple interface for defining (theoretical) quantum spin models; sliders are automatically created to vary the parameters in the models; and several plots are automatically created to visualize the results. Within the program, several measured (experimental) data sets are included for a variety of real molecules. These provide the opportunity to experience the modeling process by varying the parameters in the model and exploring how the simulated results compare to the measured data. The interactions between neighboring quantum magnetic moments ("spins") are modeled using the Heisenberg model; calculations are carried out by numerically diagonalizing the matrix representation of the Heisenberg Hamiltonian; and plots display the energy spectrum, magnetization, and magnetic susceptibility as a function of temperature and magnetic field. This simulation is a "Fully Integrated Tool for Magnetic Analysis in Research & Teaching," so we also refer to it with the acronym "FIT-MART". FIT-MART was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking ejs_fitmart.jar file will run the package if Java is installed. In future versions of this simulation, curricular materials will be included to help students to learn about magnetism, and automated fitting routines will be included to help researchers quickly and easily model experimental data. FIT-MART was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking ejs_fitmart.jar file will run the package if Java is installed.

Engelhardt, Larry; Garland, Chad; Rainey, Cameron; Freeman, Austin

2012-07-27

118

Circuit theory and model-based inference for landscape connectivity  

USGS Publications Warehouse

Circuit theory has seen extensive recent use in the field of ecology, where it is often applied to study functional connectivity. The landscape is typically represented by a network of nodes and resistors, with the resistance between nodes a function of landscape characteristics. The effective distance between two locations on a landscape is represented by the resistance distance between the nodes in the network. Circuit theory has been applied to many other scientific fields for exploratory analyses, but parametric models for circuits are not common in the scientific literature. To model circuits explicitly, we demonstrate a link between Gaussian Markov random fields and contemporary circuit theory using a covariance structure that induces the necessary resistance distance. This provides a parametric model for second-order observations from such a system. In the landscape ecology setting, the proposed model provides a simple framework where inference can be obtained for effects that landscape features have on functional connectivity. We illustrate the approach through a landscape genetics study linking gene flow in alpine chamois (Rupicapra rupicapra) to the underlying landscape.

Hanks, Ephraim M.; Hooten, Mevin B.

2013-01-01

119

ATPG for Reversible Circuits using Technology-Related Fault Models  

Microsoft Academic Search

We address the problem of test set generation and test set reduction, to first detect, and later localize faults occurring in reversible circuits. Reversible Computation has high promise of low power consumption. Some new fault models are first presented here. An explanation of the new fault models is made based on a physical realization representing the state of the art

Jeff S. Allen; Jacob D. Biamonte; Marek A. Perkowski

120

Circuit Modeling of a Small Broadband Conical Antenna  

Microsoft Academic Search

Equivalent circuit modeling methodology is proposed in this letter for a small broadband antenna composed of a conical monopole with metallic parasitic elements, a capacitive disk, and a dielectric substrate around the feed region. This omnidirectional antenna provides broadband performances over the whole bandwidth with a height limited to a one-eighth wavelength associated to the lowest frequency. The proposed modeling

Sbastien Palud; Franck Colombel; Mohamed Himdi; Cyrille Le Meins

2009-01-01

121

A novel circuit model for PEM fuel cells  

Microsoft Academic Search

The proton exchange membrane (PEM) fuel cell is being investigated as an alternate power source for various applications like transportation and emergency power supplies. The paper presents a novel circuit model for a PEM fuel cell that can be used to design and analyze fuel-cell power system. The PSPICE-based model uses BJTs and LC elements available in the PSPICE library

D. Yu; S. Yuvarajan

2004-01-01

122

Equivalent-Circuit Modeling of Nonradiative Surface Plasmon Energy Transfer Along the Metallic Nanowire  

Microsoft Academic Search

An analytical methodology for establishing an equivalent-circuit network of nonradiative surface plasmon (SP) energy transport along the metallic nanowire (MNW) is presented. To find out the passive elements for MNW, the SP dispersion and damping relation through modified Bessel function electro- magnetic (EM) field expansion was derived, thus demonstrating the low-pas transmission-line (TL) model. Specifically, the low- pass TL parameters,

Kyungjun Song; Pinaki Mazumder

2011-01-01

123

Thermoacoustic resonance effect and circuit modelling of biological tissue  

NASA Astrophysics Data System (ADS)

In this letter, thermoacoustic resonance effect is predicted from theoretical analysis with series resistor-inductor-capacitor resonance circuit model and then observed experimentally using muscle tissue illuminated by multi-pulse microwave source. Through model fitting, the circuit parameters are extracted to characterize quantitatively the resonant response of the tissue. Coherent demodulation is applied to obtain the enhanced signal-to-noise ratio and spatial information by treating tissue as a communication channel. This physical phenomenon shows significantly higher sensitivity than conventional single microwave pulse induced thermoacoustic effect, enabling the potential design of low-power thermoacoustic imaging device for portable and on-site diagnosis.

Gao, Fei; Zheng, Yuanjin; Feng, Xiaohua; Ohl, Claus-Dieter

2013-02-01

124

Proximity detector circuits: an attractive alternative to tunnel diode oscillators for contactless measurements in pulsed magnetic fields  

SciTech Connect

A new radio frequency oscillator circuit based on a proximity detector integrated circuit is described as an alternative for the traditional tunnel diode oscillator used for pulsed magnetic field measurements at low temperatures. The new circuit has been successfully applied to measure the superconducting upper critical field in Ba{sub 0.55}K{sub 0.45}Fe{sub 2}As{sub 2} single crystfl.ls up to 60 T. The new circuit design avoids many of the problems associated with tunnel diode circuits while keeping the advantages of contact less measurements in pulsed magnets.

Altarawneh, Moaz M [Los Alamos National Laboratory; Mielke, Charles H [Los Alamos National Laboratory

2009-01-01

125

Analysis and optimization of microwave circuits and devices using neural network models  

Microsoft Academic Search

This paper presents a new approach to microwave circuit analysis and optimization featuring neural network models at either device or circuit levels. At the device level, the neural network represents a physics-oriented FET model yet without the need to solve device physics equations repeatedly during optimization. At the circuit level, the neural network speeds up optimization by replacing repeated circuit

A. Hafid Zaabab; Q. J. Zhang; M. Nakhla

1994-01-01

126

Thickness Minimized Magnetic Circuit for Rotary-Type Voice Coil Motor  

NASA Astrophysics Data System (ADS)

As the demand for small-form-factor disk drives for mobile devices increases, the miniaturization of voice coil motor (VCM) actuators playing important roles in track seeking and track following is an issue. In this study, we have determined that a multisegmented magnet array (MSMA) can reduce the total thickness of the magnetic circuit for a rotary-type VCM without changing the coil and air gap parameters.

Jeong, Jaehwa; Lee, Jun-Hee; Yoon, Hyoung-Kil; Gweon, Dae-Gab

2005-03-01

127

Performance comparison of various magnetic circuits of integrated microspeakers and dynamic receivers used for mobile phones  

NASA Astrophysics Data System (ADS)

An integrated device (a microspeaker and dynamic receiver within one structure) has been developed to actualize efficient size reduction. In this article, three magnetic circuit structures of an integrated device are introduced and their characteristics are compared. A systematic analysis of a magnetic field is performed using finite element method analysis. In conclusion, type 1 has the highest electromagnetic force and the best acoustical characteristics.

Kim, Kwang-Seok; Kwon, Joong-Hak; Hwang, Sang-Moon; Hwang, Gun-Yong

2008-04-01

128

Nonlinear transformer model for circuit simulation  

Microsoft Academic Search

A transformer model which consists of a nonlinear core with hysteresis and multiple windings is described as implemented in DSPICE. In contrast to previous implementations, the nonlinear behavior of the new model is described by continuous piecewise-hyperbolic functions characterized by three parameters. These parameters are the same as parameters previously published in the literature. A loop-traversing algorithm has been implemented

John H. Chan; Andrei Vladimirescu; Xiao-chun Gao; Peter Liebmann; John Valainis

1991-01-01

129

Equivalent Circuits of Repeater Antennas for Wireless Power Transfer via Magnetic Resonant Coupling  

NASA Astrophysics Data System (ADS)

Recently, expectations from the technology of wireless power transfer via magnetic resonant coupling have increased. Magnetic resonant coupling is a new technology that achieves power transfers across a large air gap by using transmitting and receiving antennas. However, repeater antennas enable power transmission across even larger distance. These repeater antennas without cross coupling can be expressed as a T-type equivalent circuit. The equivalent circuit including cross coupling and mutual inductance, which is related to the antenna position, has not been studied. This paper proposes a novel way to represent the repeater antenna by equivalent circuit and a way to determine the mutual inductance and verified by performing electromagnetic field analysis and an experiment.

Imura, Takehiro

130

Transmission line model with skin effect for generic circuit simulator  

NASA Astrophysics Data System (ADS)

The paper presents a model of transmission line in a generic circuit simulator (ngspice) enhanced by skin effect representation. The proposed model is available in a form of a subcircuit, parameterized by so-called corner frequency - parameter dependent on line material and geometry, indicating frequency for which skin-induced losses start to become apparent. Proposed model is validated by comparison with wide range of SPECTRE simulation results and also some TDR-based measurement of long transmission lines.

Opalska, Katarzyna

2012-05-01

131

Compact Physics-Based Circuit Models for Graphene Nanoribbon Interconnects  

Microsoft Academic Search

Physics-based equivalent circuit models are presented for armchair and zigzag graphene nanoribbons (GNRs), and their conductances have been benchmarked against those of carbon nanotubes and copper wires. Atomically thick GNRs with smooth edges can potentially have smaller resistances compared with copper wires with unity aspect ratios for widths below 8 nm and stacks of noninteracting GNRs can have substantially smaller

Azad Naeemi; James D. Meindl

2009-01-01

132

Lightning modelling: From 3D to circuit approach  

Microsoft Academic Search

The topic of this study is electromagnetic environment and electromagnetic interferences (EMI) effects, specifically the modelling of lightning indirect effects [1] on aircraft electrical systems present on deported and highly exposed equipments, such as nose landing gear (NLG) and nacelle, through a circuit approach. The main goal of the presented work, funded by a French national project: PREFACE, is to

H. Moussa; M. Abdi; F. Issac; D. Prost

2012-01-01

133

Medium voltage SF6 circuit-breaker arc model application  

Microsoft Academic Search

This paper presents an arc model used to evaluate the SF6 circuit-breaker interruption capacity on non-completely standardized conditions. A method is shown to calculate the arc parameters and their application on an electromagnetic transients program. Tests and simulations were carried out concerning transformer fed fault and short-line fault.

Lucilius Carlos Pinto; Luiz Cera Zanetta Jr

2000-01-01

134

Sensitivity of HF Circuit Simulations to Electron Density Models.  

National Technical Information Service (NTIS)

The dependence of HF propagation parameters on the form of the electron density model used in circuit simulation calculations is investigated. It is seen that for identical values of the F2 region critical frequency and maximum height, no one of the selec...

C. M. Rush W. R. Edwards

1975-01-01

135

Modeling and simulation of printed circuit board drop test  

Microsoft Academic Search

Modeling and simulation of drop tests for printed circuit boards (PCB) was conducted for flip chip on board (FCOB) assemblies. The PCB test vehicle has dimensions of 185 mm by 150 mm with 6 large flip chips (8 mm×8 mm) and 6 small flip chips (3 mm×3 mm) mounted with underfill encapsulation. The PCB specimen was clamped at two edges

Y. Q. Wang; K. H. Low; F. X. Che; H. L. J. Pang; S. P. Yeo

2003-01-01

136

Mapping and cracking sensorimotor circuits in genetic model organisms.  

PubMed

One central goal of systems neuroscience is to understand how neural circuits implement the computations that link sensory inputs to behavior. Work combining electrophysiological and imaging-based approaches to measure neural activity with pharmacological and electrophysiological manipulations has provided fundamental insights. More recently, genetic approaches have been used to monitor and manipulate neural activity, opening up new experimental opportunities and challenges. Here, we discuss issues associated with applying genetic approaches to circuit dissection in sensorimotor transformations, outlining important considerations for experimental design and considering how modeling can complement experimental approaches. PMID:23719159

Clark, Damon A; Freifeld, Limor; Clandinin, Thomas R

2013-05-22

137

Time-dependent information transmission in a model regulatory circuit  

NASA Astrophysics Data System (ADS)

Many biological regulatory systems respond with a physiological delay when processing signals. A simple model of regulation which respects these features shows how the ability of a delayed output to transmit information is limited: at short times by the time scale of the dynamic input, at long times by that of the dynamic output. We find that topologies of maximally informative networks correspond to commonly occurring biological circuits linked to stress response and that circuits functioning out of steady state may exploit absorbing states to transmit information optimally.

Mancini, F.; Wiggins, C. H.; Marsili, M.; Walczak, A. M.

2013-08-01

138

Magnetic Multipole Field Model  

NSDL National Science Digital Library

The EJS Magnetic Multipole Field Model shows the field of a magnetic dipole or quadrupole with little compasses that indicate direction and relative field strength. A slider changes the angular orientation of the dipole and a movable compass shows the magnetic field direction and magnitude. Compass values can be recorded into a data table and analyzed using a built-in data analysis tool. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. The Magnetic Multipole Field model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_MagneticMultipoleField.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang; Cox, Anne; Franciscouembre

2010-02-14

139

Students' mental models of electricity in simple DC circuits  

NASA Astrophysics Data System (ADS)

This study presents the results of research into middle school students' knowledge about the nature and mechanisms of action of electricity in simple DC circuits. Sixth, seventh, and eighth graders (n = 99) were asked a series of questions about the roles of bulbs, batteries, wires, and electricity in circuits. Almost half the number of students (n = 42) were found to have used detailed, well-defined, and logically consistent mental models based on their responses. A total of 15 different detailed mental models were documented in these students that belonged to one of four different general model types: (1)round trip flow using both ends of the battery, (2)round trip flow using one end of the battery, (3)one way flow using both ends of the battery, and (4)one way flow using one end of the battery. These models were composed of eight different components that each represented the students' conceptions of different parts or aspects of the circuit. A majority of the students (n = 75) were found to have used one of the general model types, 22 used more than one general model types, and 2 were categorized as undetermined as to whether they used any or no general model type at all. A theoretical framework is outlined which explains the formation of initial, synthetic, and scientific models and how this study informs that framework. The relationship between mental models and conceptions and how it relates to this study is also discussed.

Isola, Andrew C., III

1999-12-01

140

Probabilistic Analysis of a Rotary Position Sensor and Magnet Circuit  

Microsoft Academic Search

The probabilistic analysis of the magnetic field driving a Hall Effect sensor in a rotary application is described. The resulting field strength distributions offer a statistical view of several individually varying parameters that affect the output. These results are further utilized to understand the most efficient methods to reduce variation in the field at the sensor.

Jon S. Pointer

141

Equivalent circuit modeling of losses and dispersion in single and coupled lines for microwave and millimeter-wave integrated circuits  

Microsoft Academic Search

Losses and dispersion in open inhomogeneous guided-wave structures such as microstrips and other planar structures at microwave and millimeter-wave frequencies and in MMICs (monolithic microwave integrated circuits) have been modeled with circuits consisting of ideal lumped elements and lossless TEM (transverse electromagnetic) lines. It is shown that, given a propagation structure for which numerical techniques to compute the propagation characteristics

Vijai K. Tripathi; Achim Hill

1988-01-01

142

Modelling RF interference effects in integrated circuits  

Microsoft Academic Search

The disturbance effects in complex electronic systems, subjected to a high power microwave (HPM), continuous wave (CW) or pulse irradiation, show a conversion of the injected high frequency (HF) out-of-band signal to a low frequency (LF) inband signal. In this paper, a behavioural model is presented that combines HF and LF subcircuits to predict the effect of radio frequency interference

N. L. Whyman; J. F. Dawson

2001-01-01

143

Short-circuit analysis of permanent-magnet generators  

Microsoft Academic Search

Permanent-magnet generators (PMG) have rapidly become important in renewable energy systems, portable and standby generating systems, and in many new applications in industrial, utility, aerospace and automotive sectors. While there has been some discussion of ldquofault tolerance,rdquo and fault testing of an 8MW machine has recently been reported, understanding the behavior of faulted PMGs remains far from complete. This paper

K. W. Klontz; T. J. E. Miller; H. Karmaker; P. Zhong

2009-01-01

144

Noise and Dephasing from Surface Magnetic States in Superconducting Circuits  

NASA Astrophysics Data System (ADS)

Superconducting qubits are a leading candidate for scalable quantum information processing. In order to realize the full potential of these qubits, it is necessary to develop a more complete understanding of the microscopic physics that governs dissipation and dephasing of the quantum state. In the case of the Josephson phase and flux qubits, the dominant dephasing mechanism is an apparent low-frequency magnetic flux noise with a 1/f spectrum and a magnitude of several ??0/Hz^ 1/2 at 1 Hz, where ?0= h/2e is the magnetic flux quantum. Recent qubit results are compatible with the excess low-frequency noise measured by researchers at Berkeley more that 20 years ago in a series of experiments on SQUIDs cooled to millikelvin temperatures. The origin of this excess noise was never understood. Here we describe studies of flux noise and temperature- dependent magnetization in SQUIDs cooled to millikelvin temperatures. We observe that the flux threading the SQUIDs increases as 1/T as temperature is lowered; moreover, the flux change is proportional to the density of trapped vortices. The data is compatible with the thermal polarization of unpaired surface spins in the trapped fields of the vortices. In the absence of trapped flux, we observe evidence of spin- glass freezing at low temperature. These results suggest a microscopic explanation for the universal 1/f flux noise in SQUIDs and superconducting qubits, and suggest that suitable surface treatments of the superconducting films will lower the density of magnetic states, leading to superconducting devices with lower noise and solid-state qubits with improved coherence times.

McDermott, Robert

2009-03-01

145

Transcutaneous battery recharging by volume conduction and its circuit modeling.  

PubMed

Many implantable devices require large capacity batteries implanted in the body. Transcutaneous battery recharging can effectively maintain the longevity of these implants. Based on this consideration we have developed a transcutaneous battery recharging circuit unit which takes advantages of skin volume conduction. This unit is able to pass 2.8 mA from the outside to the inside of pig skin with a current transmitting efficiency of 27%. Theoretical analysis and experiments have validated that this battery recharging technology is an effective approach. In this research we have constructed an x-type equivalent circuit model of skin volume conduction for battery recharging. The parameters of the x-type equivalent circuit can be easily measured and used to evaluate the battery charging system characteristics, such as the rechargeable prerequisite and the current transmitting efficiency limitation. We have analyzed the transcutaneous current transmitting efficiency by applying the x-type equivalent circuit model and discussed approaches for enhancing current transmitting efficiency. PMID:17945991

Tang, Zhide; Sclabassi, Robert J; Sun, Caixin; Hackworth, Steven A; Zhao, Jun; Cui, Xinyan T; Sun, Mingui

2006-01-01

146

THERMAL FLUID MODELING OF BEPCII IR QUADRUPOLE MAGNET CRYOSTAT.  

SciTech Connect

A pair of superconducting interaction region quadrupole magnets for BEPCII was designed and fabricated at Brookhaven National Laboratory, USA. The cryogenic system for the IR magnets was designed at Harbin Institute of Technology, China. This paper provides the results of thermal fluid modeling for the magnet cryostat. The numerical analyses were carried out for two types of cooling methods, the subcooled liquid helium and the supercritical helium flow. The pressure and temperature changes in the cooling circuits are given.

WANG.L.; TANG,H.M.; ZHANG,X.B.; YANG,G.D.; JIA,L.X.

2004-05-11

147

Numerical modeling of magnetic devices  

Microsoft Academic Search

We present a general approach to directly couple finite-element models with arbitrary electric circuits for application to electromagnetic devices. We describe both two-dimensional (2-D) and three-dimensional (3-D) transient finite-element models, with emphasis on 3-D using a T-? formulation. For 3-D transient and circuit coupling, the derivation of the induced voltage is an integral part of the coupling approach, and the

P. Zhou; W. N. Fu; D. Lin; S. Stanton; Z. J. Cendes

2004-01-01

148

Development of a numerical computer code and circuit element models for simulation of firing systems  

SciTech Connect

Numerical simulation of firing systems requires both the appropriate circuit analysis framework and the special element models required by the application. We have modified the SPICE circuit analysis code (version 2G.6), developed originally at the Electronic Research Laboratory of the University of California, Berkeley, to allow it to be used on MSDOS-based, personal computers and to give it two additional circuit elements needed by firing systems--fuses and saturating inductances. An interactive editor and a batch driver have been written to ease the use of the SPICE program by system designers, and the interactive graphical post processor, NUTMEG, supplied by U. C. Berkeley with SPICE version 3B1, has been interfaced to the output from the modified SPICE. Documentation and installation aids have been provided to make the total software system accessible to PC users. Sample problems show that the resulting code is in agreement with the FIRESET code on which the fuse model was based (with some modifications to the dynamics of scaling fuse parameters). In order to allow for more complex simulations of firing systems, studies have been made of additional special circuit elements--switches and ferrite cored inductances. A simple switch model has been investigated which promises to give at least a first approximation to the physical effects of a non ideal switch, and which can be added to the existing SPICE circuits without changing the SPICE code itself. The effect of fast rise time pulses on ferrites has been studied experimentally in order to provide a base for future modeling and incorporation of the dynamic effects of changes in core magnetization into the SPICE code. This report contains detailed accounts of the work on these topics performed during the period it covers, and has appendices listing all source code written documentation produced.

Carpenter, K.H. (Kansas State Univ., Manhattan, KS (USA). Dept. of Electrical and Computer Engineering)

1990-07-02

149

Model of photovoltaic cell circuits under partial shading  

Microsoft Academic Search

The PV-cell and natural energy production systems have been much attracted. Together with global warning and extensive applications of solar power electric generation, defects on PV-cell under the partial shading become interesting technical issue. This paper investigates the equivalent circuit model and its characteristics under the partial shading condition. And we have clarified the mechanism of PV-cell under the partial

Atsushi Kajihara; A. T. Harakawa

2005-01-01

150

A physics-based MOSFET noise model for circuit simulators  

Microsoft Academic Search

Discussed is a physics-based MOSFET noise model that can accurately predict the noise characteristics over the linear, saturation, and subthreshold operating regions but which is simple enough to be implemented in any general-purpose circuit simulator. Expressions for the flicker noise power are derived on the basis of a theory that incorporates both the oxide-trap-induced carrier number and correlated surface mobility

K. K. Hung; P. K. Ko; C. Hu; Y. C. Cheng

1990-01-01

151

Cirque du Circuit  

NSDL National Science Digital Library

This chapter and the next few that follow will be devoted primarily to electric circuits. Understanding the operation of electric circuits and the devices that go into circuits requires a basic understanding of the scientific models of electricity and magnetism. To truly understand electric circuits, there's no substitute for physically messing around with them. This chapter provides you with the opportunity to let your "inner scientist" shine through as you conduct experiments using special software that can be downloaded from the NSTA Web site.

Robertson, William C.

2005-01-01

152

Heat treatment of electric motor magnetic circuits of cold rolled steel  

Microsoft Academic Search

A method for annealing stator magnetic circuits of 2011, 2012, and 2013 steels for series 4A56 motors by using induction heating of the welded packets in air atmosphere has been developed. The machine capacity is up to 160 kg\\/hr, the power 50 kW, and the current frequency 2.4 kHz. Consumption of electric power does not exceed 0.3 kWh\\/kg. Savings were

L. S. Bulatova; V. G. Boltin; M. P. Bystrov

1988-01-01

153

Equivalent Circuit Parameter Calculation of Interior Permanent Magnet Motor Involving Iron Loss Resistance Using Finite Element Method  

Microsoft Academic Search

In this paper, we propose a method to calculate the equivalent circuit parameters of interior permanent magnet motors including iron loss resistance using the finite element method. First, the finite element analysis considering harmonics and magnetic saturation is carried out to obtain time variations of magnetic fields in the stator and the rotor core. Second, the iron losses of the

Katsumi Yamazaki

2004-01-01

154

Rotational Motion of Break Arcs Driven by Radial Magnetic Field in a DC Resistive Circuit  

NASA Astrophysics Data System (ADS)

Break arcs are generated between silver electrical contacts in a DC 42V-10A resistive circuit. Break arcs are driven by the radial magnetic field. The magnetic field is formed between the electrical contacts with a permanent magnet embedded in the cathode. The arc motion is taken with a high-speed camera and contact surfaces are observed after break operations. Experimental results with the magnet are compared with those without the magnet to confirm the effect of the embedded magnet. For break operations with the magnet following results are shown. Break arcs are rotationally driven by the radial magnetic field in the direction according to Lorentz force. The shortening effect of the arc duration is confirmed. The traces of the arc spots on the contact surfaces are ring-shaped, wide and uniform. This result shows the prevention effect of local erosion of electrical contacts. The rotational frequency of the break arc depends on the Lorentz force with the radial magnetic field.

Sekikawa, Junya; Kubono, Takayoshi

155

A maximum power control of wind generator system using a permanent magnet synchronous generator and a boost chopper circuit  

Microsoft Academic Search

The wind generator system using a boost chopper for generation control of permanent magnet synchronous generator is proposed. And, the theoretical analysis of characteristics of power generation is discussed. By replacing the main circuit composition of generator and boost chopper with the equivalent circuit, characteristics for generating power and DC output voltage were expressed by the function of duty ratio

Kenji Amei; Y. Takayasu; T. Ohji; M. Sakui

2002-01-01

156

3-D finite element analysis of magnetic blowout forces acting on the arc in molded case circuit breakers  

Microsoft Academic Search

It is necessary, for the optimum design of molded case circuit breakers, to analyze magnetic blowout forces acting on the arc in the contact systems when the circuit breakers interrupt fault currents. In this paper, the forces generated by the arc current and the flux density are obtained by using 3-D finite element analysis, taking into account the current distribution

Shokichi Ito; Yoshihiro Kawase; Hiroyuki Mori

1997-01-01

157

An electrical circuit model for simulation of indoor radon concentration.  

PubMed

In this study, a new model based on electric circuit theory was introduced to simulate the behaviour of indoor radon concentration. In this model, a voltage source simulates radon generation in walls, conductivity simulates migration through walls and voltage across a capacitor simulates radon concentration in a room. This simulation considers migration of radon through walls by diffusion mechanism in one-dimensional geometry. Data reported in a typical Greek house were employed to examine the application of this technique of simulation to the behaviour of radon. PMID:22668758

Musavi Nasab, S M; Negarestani, A

2012-06-04

158

Experimental validation of circuit models for bulk current injection (BCI) test on shielded coaxial cables  

Microsoft Academic Search

In order to validate, by means of measurement, some existing equivalent circuit models for the bulk current injection (BCI) test, a procedure is proposed to develop a proper circuit model for the injection clamp and the obtained circuit is introduced into the global one representing the overall cable. A suitable experimental set-up has been built and used. The measured induced

G. Antonini; A. Ciccomancini Scogna; A. Orlandi; R. M. Rizzi

2004-01-01

159

A Direct Power Injection Model for Immunity Prediction in Integrated Circuits  

Microsoft Academic Search

This paper introduces a complete simulation model of a direct power injection (DPI) setup, used to measure the immunity of integrated circuits to conducted continuous-wave interference. This model encompasses the whole measurement setup itself as well as the integrated circuit under test and its environment (printed circuit board, power supply). Furthermore, power losses are theoretically computed, and the most significant

Ali Alaeldine; Richard Perdriau; Mohamed Ramdani; Jean-Luc Levant; M'hamed Drissi

2008-01-01

160

A Direct Power Injection Model for Immunity Prediction in Integrated Circuits  

Microsoft Academic Search

This paper introduces a complete simulation model of a Direct Power Injection (DPI) setup, used to measure the immunity of integrated circuits to conducted continuous-wave interference. This model encompasses the whole measurement setup itself as well as the integrated circuit under test and its environment (printed circuit board, power supply). Furthermore, power losses are theoretically computed, and the most significant

Ali Alaeldine; Richard Perdriau; Mohamed Ramdani; Jean-Luc Levant

2006-01-01

161

Single axis controlled hybrid magnetic bearing for left ventricular assist device: hybrid core and closed magnetic circuit.  

PubMed

In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD. PMID:21595710

da Silva, Isaias; Horikawa, Oswaldo; Cardoso, Jose R; Camargo, Fernando A; Andrade, Aron J P; Bock, Eduardo G P

2011-05-01

162

Microwave circuit model of the three-port transistor laser  

NASA Astrophysics Data System (ADS)

Based on an earlier charge control analysis, we have constructed a microwave circuit model of a three-port quantum-well (QW) transistor laser (TL) by extending Kirchhoff's law to include electron-photon interaction, to yield an electrical-optical form of Kirchhoff's law. The TL circuit model includes both intrinsic device elements and extrinsic parasitic elements, and fits accurately measured microwave S-parameters upto 20 GHz and matches also measured eye-diagram data up to 13 Gb/s (equipment-limited). The TL model yields both electrical and optical device parameters as well as physical quantities such as QW charge density, nQW~1016 cm-3, which is useful in the analysis of the device physics of TL operation. The low density indicates that the base QW charge level is not as important as the current driving the QW and supplying electron-hole recombination, and implies that the quasi-Fermi level is discontinuous in the TL base. The model is used to simulate a directly modulated TL up to 40 Gb/s, for example, a TL employed in an optical communication link.

Then, H. W.; Feng, M.; Holonyak, N.

2010-05-01

163

Equivalent circuit model for plasmonic slot waveguides networks  

NASA Astrophysics Data System (ADS)

Plasmonic slot waveguide (PSW) provides unique ability to confine the light in few nanometers only. It also allows for near perfect transmission through sharp bends. These features motivate utilizing the PSW in various on chip applications that require nanoscale manipulation of light. The main challenge of using these PSWs are the associated high losses that allow for propagation length of ~10 ?m only. However, this constraint plays a minimal rule for circuits designed to have footprint in the order of few micrometers only. Thus, designing PSW with compact size and superior performance is of prime essential. Finite difference time domain (FDTD) is usually utilized for modeling of such networks. This technique is, however, inefficient as it requires very fine grid and carful manipulation of the boundary condition to avoid spurious reflections. In the paper, we present our recent equivalent circuit model that is capable of accurately modeling the various junctions including T and X shapes. This model is highly efficient and allows for obtaining a closed form expression of the response of any network of PSW with accuracy comparable to the FDTD results.

Swillam, Mohamed A.; Lin, Charles; Helmy, Amr S.

2013-03-01

164

Substrate resistance modeling and circuit-level simulation of parasitic device coupling effects for CMOS I\\/O circuits under ESD stress  

Microsoft Academic Search

In CMOS technologies, the layout and placement of devices and substrate contacts can have significant impact on the circuit's ESD (electrostatic discharge) performance due to their interactions through the common silicon substrate. To perform accurate circuit-level ESD simulation, a circuit model for the silicon substrate is needed. In this work, we propose a new substrate resistance network model. In addition,

Tong Li; C.-H. Tsai; E. Rosenbaum; S.-M. Kang

1998-01-01

165

Data Mining Approaches for Modeling Complex Electronic Circuit Design Activities  

SciTech Connect

A printed circuit board (PCB) is an essential part of modern electronic circuits. It is made of a flat panel of insulating materials with patterned copper foils that act as electric pathways for various components such as ICs, diodes, capacitors, resistors, and coils. The size of PCBs has been shrinking over the years, while the number of components mounted on these boards has increased considerably. This trend makes the design and fabrication of PCBs ever more difficult. At the beginning of design cycles, it is important to estimate the time to complete the steps required accurately, based on many factors such as the required parts, approximate board size and shape, and a rough sketch of schematics. Current approach uses multiple linear regression (MLR) technique for time and cost estimations. However, the need for accurate predictive models continues to grow as the technology becomes more advanced. In this paper, we analyze a large volume of historical PCB design data, extract some important variables, and develop predictive models based on the extracted variables using a data mining approach. The data mining approach uses an adaptive support vector regression (ASVR) technique; the benchmark model used is the MLR technique currently being used in the industry. The strengths of SVR for this data include its ability to represent data in high-dimensional space through kernel functions. The computational results show that a data mining approach is a better prediction technique for this data. Our approach reduces computation time and enhances the practical applications of the SVR technique.

Kwon, Yongjin [Ajou University, Suwon, South Korea; Omitaomu, Olufemi A [ORNL; Wang, Gi-Nam [Ajou University, Suwon, South Korea

2008-01-01

166

Simple model of a photoacoustic system as a CR circuit  

NASA Astrophysics Data System (ADS)

We introduce the photoacoustic educational system (PAES), by which we can identify which gas causes the greenhouse effect in a classroom (Kaneko et al 2010 J. Chem. Educ. 87 202-4). PAES is an experimental system in which a pulse of infrared (IR) is absorbed into gas as internal energy, an oscillation of pressure (sound) appears, and then we can measure the absorptance of IR by the strength of sound. In this paper, we construct a simple mathematical model for PAES which is equivalent to the CR circuit. The energy absorption of an IR pulse into gas corresponds to the charge of a condenser and the heat diffusion to the outside corresponds to the energy dissipation by electric resistance. We analyse the experimental results by using this simple model, and check its validity. Although the model is simple, it explains phenomena occurring in PAES and can be a good educational resource.

Fukuhara, Akiko; Kaneko, Fumitoshi; Ogawa, Naohisa

2012-05-01

167

Circuit model for bulk current injection test on shielded coaxial cables  

Microsoft Academic Search

A SPICE circuit model for the evaluation of the effects of the bulk current injection test on coaxial shielded cables is developed. The proposed equivalent circuits do not need the usual subdivision of the circuits in elementary cells, it is valid in both frequency and time domain and is based on the exact solution of the equations stemming from a

Antonio Orlandi

2003-01-01

168

Physics and process-based bipolar transistor modeling for integrated circuit design  

Microsoft Academic Search

Many applications require circuits to be operated close to the performance limits of current silicon (production) processes to meet the required circuit specifications for, e.g., high speed, low noise, and low power consumption. Therefore, the circuits must be carefully optimized by selecting the individual transistor configurations. As a consequence, model parameters for a large variety of configurations (100 or more)

Michael Schroter; Hans-Martin Rein; Winfried Rabe; Reinhard Reimann; Hans-Joachim Wassener; Andreas Koldehoff

1999-01-01

169

Physics-Based Passivity-Preserving Parameterized Model Order Reduction for PEEC Circuit Analysis  

Microsoft Academic Search

The decrease of integrated circuit feature size and the increase of operating frequencies require 3-D electromagnetic methods, such as the partial element equivalent circuit (PEEC) method, for the analysis and design of high-speed circuits. Very large systems of equations are often produced by 3-D electromagnetic methods, and model order reduction (MOR) methods have proven to be very effective in combating

Francesco Ferranti; Giulio Antonini; Tom Dhaene; Luc Knockaert; Albert E. Ruehli

2011-01-01

170

Device Models, Circuit Simulation, And Computer-controlled Measurements For The IGBT  

Microsoft Academic Search

The implementation of the recently dcvel- oped IGBT device model into a circuit simulation program is described. It is shown that the circuit simulation program rapidly and robustly simulates the dynamic behavior of the IGBT for general external drive, load, and feedback circuit configurstions. The algorithms used to extract the IGBT de- vice parameters from computer-controlled measurements are also described,

ALLEN R HEFNER

1990-01-01

171

Modeling and simulation of insulated-gate field-effect transistor switching circuits  

Microsoft Academic Search

A new equivalent circuit for the insulated-gate field-effect transistor (IGFET) is described. This device model is particularly useful for computer-aided analysis of monolithic integrated IGFET switching circuits. The results of computer simulations using the new equivalent circuit are in close agreement with experimental observations. As an example of a practical application, simulation results are shown for an integrated circuit IGFET

HAROLD SHICHMAN; DAVID A. HODGES

1968-01-01

172

Impact of load on winding inductances of permanent magnet generators with multiple damping circuits using energy perturbation  

Microsoft Academic Search

A computer-aided method for determining the impact of load on winding inductances and other machine parameters of permanent magnet generators with multiple damping circuits is presented. The method is general in nature so that it can be applied to detailed computer-aided design processes of permanent magnet generator systems. The method is based on use of the abc frame of reference

A. A. Arkadan; N. A. Demerdash; J. G. Vaidya; M. J. Shah

1988-01-01

173

Computer model simulation of null-flux magnetic suspension and guidance  

SciTech Connect

This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.

He, Jianliang; Rote, D.M.

1992-06-01

174

Computer model simulation of null-flux magnetic suspension and guidance  

SciTech Connect

This paper discusses the magnetic force computations in a null-flux suspension system using dynamic circuit theory. A computer simulation model that can be used to compute magnetic forces and predict the system performance is developed on the basis of dynamic circuit theory. Numerical examples are presented to demonstrate the application of the model. The performance of the null-flux suspension system is simulated and discussed. 8 refs.

He, Jianliang; Rote, D.M.

1992-01-01

175

Instantaneous magnetic field distribution in brushless permanent magnet DC motors. I. Open-circuit field  

Microsoft Academic Search

An analytical technique for predicting the instantaneous magnetic field distribution in the airgap region of radial-field topologies of brushless permanent-magnet DC motors, under any specified load condition and accounting implicitly for the stator winding current waveform and the effect of stator-slot-openings, has been developed. It is based on the superposition of the component fields due to the permanent magnet and

Z. Q. Zhu; David Howe; Ekkehard Bolte; Bemd Ackermann

1993-01-01

176

Dynamic analysis of radial force density in brushless DC motor using 3-D equivalent magnetic circuit network method  

SciTech Connect

The distribution of radial force density in brushless permanent magnet DC motor is not uniform in axial direction. The analysis of radial force density has to consider the 3-D shape of teeth and overhand, because the radial force density causes vibration and acts on the surface of teeth inconstantly. For the analysis, a new 3-D equivalent magnetic circuit network method is used to account the rotor movement without remesh. The radial force density is calculated and analyzed by Maxwell stress tensor and discrete Fourier transform (DFT) respectively. The results of 3-D equivalent magnetic circuit method have been compared with the results of 3-D FEM.

Hur, J.; Chun, Y.D.; Lee, J.; Hyun, D.S. [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Electrical Engineering

1998-09-01

177

A model of ball lightning as a magnetic knot with linked streamers  

Microsoft Academic Search

We develop a topological model of ball lightning which explains its stability by the coupling of an air ball to a magnetic knot, a magnetic field with linked magnetic lines. Assuming that currents flow inside the ball, along short-circuited linked streamers following the lines of V x B, the lifetime, energy, and radiated power of the average ball are correctly

Antonio F. Rafiada; Mario Soler; José L. Trueba

1998-01-01

178

Delay modeling of bipolar ECL/EFL (Emitter-Coupled Logic/Emitter-Follower-Logic) circuits  

NASA Astrophysics Data System (ADS)

This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance of the circuits with a minimum expenditure of computation time. This goal is achieved by the use of proper circuit transient models on which analytical delay expressions can be derived with accurate results. The delay-model developed in this report is general enough to handle complex digital circuits with multiple inputs or/and multiple levels. The important effects of input slew rate are also included in the model.

Yang, Andrew T.

1986-08-01

179

Development of a circuit model to describe the advection-diffusion equation for air pollution  

Microsoft Academic Search

A circuit model for calculating pollutant concentration from an area source is derived. This model includes various loss, production and transfer terms and can be used by grid modellers seeking to build a more sophisticated description of the PBL. After analysis of exchange\\/removal processes operating in the PBL by using the circuit model, we find that the near ground steady-state

Ben-Jei Tsuang; Jiun-Pyng Chao

1997-01-01

180

A neural network modeling approach to circuit optimization and statistical design  

Microsoft Academic Search

The trend of using accurate models such as physics-based FET models, coupled with the demand for yield optimization results in a computationally challenging task. This paper presents a new approach to microwave circuit optimization and statistical design featuring neural network models at either device or circuit levels. At the device level, the neural network represents a physics-oriented FET model yet

A. Hafid Zaabab; Qi-Jun Zhang; Michel Nakhla

1995-01-01

181

Iterative Performance Model Upgradation in Geometric Programming Based Analog Circuit Sizing for Improved Design Accuracy  

Microsoft Academic Search

In this paper, we propose a technique to improve the accuracy of the final design predicted by Geometric Programming based CMOS analog circuit sizing methodology. Here we use a multi-level AC performance modeling paradigm to develop the empirical models of circuit performance metrics. Performance models are then upgraded over iterations of design cycle. This iterative model up gradation in a

Samiran Dam; Pradip Mandal

2012-01-01

182

An experimentally verified IGBT model implemented in the Saber circuit simulator  

Microsoft Academic Search

A physics-based IGBT model is implemented into the general purpose circuit simulator Saber. The IGBT model includes all of the physical effects that have been shown to be important for describing IGBTs, and the model is valid for general external circuit conditions. The Saber IGBT model is evaluated for the range of static and dynamic conditions in which the device

D. M. Diebolt

1994-01-01

183

An experimentally verified IGBT model implemented in the Saber circuit simulator  

Microsoft Academic Search

A physics-based insulated gate bipolar transistor (IGBT) model is implemented in the general-purpose circuit simulator Saber. The IGBT model includes all of the physical effects that have been shown to be important for describing IGBTs, and the model is valid for general external circuit conditions. The Saber IGBT model is evaluated for the range of static and dynamic conditions in

D. M. Diebolt

1991-01-01

184

Comparison of lumped parameter and finite element magnetic modeling in a brushless DC motor  

Microsoft Academic Search

The FEM is a favored motor design tool for its high accuracy. Magnetic equivalent circuit analysis, an alternative to FEM, is becoming popular for its fair accuracy and quick repetition of computation. An equivalent circuit model of a brushless DC motor is developed and its ability to accurately predict various motor performance parameters is assessed

J. P. Wang; D. K. Lieu; W. L. Lorimer; A. Hartman

1997-01-01

185

How to model connection wires in a circuit: From physical vector fields to circuit scalar quantities  

NASA Astrophysics Data System (ADS)

Starting from the basic equations of electromagnetism, Maxwell's equations, the concepts of inductive coupling in a loop and capacitive coupling between two pieces of wire are formally explained. Inductive coupling is linked to Faraday's law and capacitive coupling to the Ampere-Maxwell law. Capacitive coupling is also inherently linked to the phenomenon of surface charges, which has been recently studied thoroughly in the literature, especially in static situations. It is shown that, when applied to the connecting wires in a circuit at higher frequencies, simple circuit theory must be significantly modified in order to take into account the effects of the two types of coupling between the wires.

Vandenbosch, Guy A. E.

2013-09-01

186

Circuital model for the spherical geodesic waveguide perfect drain  

NASA Astrophysics Data System (ADS)

The perfect drain for the Maxwell fish eye (MFE) is a non-magnetic dissipative region placed in the focal point to absorb all the incident radiation without reflection or scattering. The perfect drain was recently designed as a material with complex permittivity that depends on frequency. However, this material is only a theoretical material, so it cannot be used in practical devices. The perfect drain has been claimed as necessary for achieving super-resolution (Leonhardt 2009 New J. Phys. 11 093040), which has increased the interest in practical perfect drains suitable for manufacturing. Here, we present a practical perfect drain that is designed using a simple circuit (made of a resistance and a capacitor) connected to the coaxial line. Moreover, we analyze the super-resolution properties of a device equivalent to the MFE, known as a spherical geodesic waveguide, loaded with this perfect drain. The super-resolution analysis for this device is carried out using COMSOL Multiphysics. The results of simulations predict a super-resolution of up to ?/3000.

González, Juan C.; Grabovi?ki?, Dejan; Benítez, Pablo; Miñano, Juan C.

2012-08-01

187

Improvement of wireless power transmission efficiency of implantable subcutaneous devices by closed magnetic circuit mechanism.  

PubMed

Induction coils were fabricated based on flexible printed circuit board for inductive transcutaneous power transmission. The coil had closed magnetic circuit (CMC) structure consisting of inner and outer magnetic core. The power transmission efficiency of the fabricated device was measured in the air and in vivo condition. It was confirmed that the CMC coil had higher transmission efficiency than typical air-core coil. The power transmission efficiency during a misalignment between primary coil and implanted secondary coil was also evaluated. The decrease of mutual inductance between the two coils caused by the misalignment led to a low efficiency of the inductive link. Therefore, it is important to properly align the primary coil and implanted secondary coil for effective power transmission. To align the coils, a feedback coil was proposed. This was integrated on the backside of the primary coil and enabled the detection of a misalignment of the primary and secondary coils. As a result of using the feedback coil, the primary and secondary coils could be aligned without knowledge of the position of the implanted secondary coil. PMID:22806430

Jo, Sung-Eun; Joung, Sanghoon; Suh, Jun-Kyo Francis; Kim, Yong-Jun

2012-07-18

188

Geometrically Parameterized Circuit Models of Printed Circuit Board Traces Inclusive of Antenna Coupling  

Microsoft Academic Search

This paper presents a systematic methodology for the characterization of mutual couplings between antennas and printed circuit board (PCB) traces in modern mobile devices. The main approach is based on the assumption that the interfering fields produced by the antennas are not perturbed significantly by the PCB traces. The one-way coupling can thus be computed using the theory of field-excited

Piero Triverio; Stefano Grivet-Talocia; Michelangelo Bandinu; Flavio G. Canavero

2010-01-01

189

Process dependent electrical characteristics and equivalent circuit model of sol-gel based PZT capacitors  

Microsoft Academic Search

Studies of electrical properties and an equivalent circuit model is developed for ferroelectric PZT(Ti = 60%) thin film capacitors made by sol-gel spin coating with Pt electrodes. The equivalent circuit consists of two major parts: serial space charge capacitors demonstrating surface effects and parallel elements modeling the inner polycrystalline ferroelectric regions. This model is based on device physics which can

Takashi Mihara; Hitoshi Watanabe; Hiroyuki Yoshimori; C. A. Paz De Araujo; B. Melnick; L. D. McMillan

1992-01-01

190

Skin effects models for transmission line structures using generic SPICE circuit simulators  

Microsoft Academic Search

A recipe has been developed to model the skin effect for various transmission line structures. The final circuit structure to model this effect can be used with a generic SPICE circuit simulator. The ladder-like network (Yen et al, 1982) element is fairly easy to compute, and requires a minimal increase in CPU time. The model has been verified experimentally

Bidyut K. Sen; R. L. Wheeler

1998-01-01

191

Application of the cavity model to lossy power-return plane structures in printed circuit boards  

Microsoft Academic Search

Power-return plane pairs in printed circuit boards are often modeled as resonant cavities. Cavity models can be used to calculate transfer impedance parameters used to predict levels of power bus noise. Techniques for applying the cavity model to lossy printed circuit board geometries rely on a low-loss assumption in their derivations. Boards that have been designed to damp power bus

Minjia Xu; Hao Wang; Todd H. Hubing

2003-01-01

192

A Compact Model for Circuit Simulation of TFT-LCD Panel  

Microsoft Academic Search

In this paper, we report a novel compact SPICE model for circuit simulation of LCD-TVs. In this work, we generated a SPICE model for a unit cell of TFT-LCD by taking all of parasitic capacitances and resistances into account. In order to extract circuit model from a unit cell, an electrical connectivity of resistors and capacitors was generated through the

Suk-In Yoon; Sang-Ho Yoon; Chan-Yong Jung; Taeyoung Won

2006-01-01

193

Interface-modified random circuit breaker network model applicable to both bipolar and unipolar resistance switching  

NASA Astrophysics Data System (ADS)

We observed reversible-type changes between bipolar (BRS) and unipolar resistance switching (URS) in one Pt/SrTiOx/Pt capacitor. To explain both BRS and URS in a unified scheme, we introduce the ``interface-modified random circuit breaker network model,'' in which the bulk medium is represented by a percolating network of circuit breakers. To consider interface effects in BRS, we introduce circuit breakers to investigate resistance states near the interface. This percolation model explains the reversible-type changes in terms of connectivity changes in the circuit breakers and provides insights into many experimental observations of BRS which are under debate by earlier theoretical models.

Lee, S. B.; Lee, J. S.; Chang, S. H.; Yoo, H. K.; Kang, B. S.; Kahng, B.; Lee, M.-J.; Kim, C. J.; Noh, T. W.

2011-01-01

194

Practical Modeling of the Circuit Breaker ARC as a Short Line Fault Interrupter  

Microsoft Academic Search

The short-line fault interrupting ability of gas-blast circuit breakers is limited by arc energy balance processes very close to current zero. Practical calculation of the energy balance limit in a given circuit requires mathematical modeling of the arc as a circuit element. Using the combined Cassie-Mayr model, useful relations are derived for treating the limiting cases of the short-line fault

T. E. Browne

1978-01-01

195

A statistical model for determining the minimum size in integrated circuits  

Microsoft Academic Search

A physical-statistical model for determining the minimum linewidth in integrated circuits of any kind is described. The minimum linewidth in integrated circuits is determined on the basis of a physical-statistical model for layout of the circuit pattern. First, the minimum spot size, 2.5 nm, of photon, electron, or ion beams, is determined, based on the Heisenberg uncertainty principle, minimum molecule

J. T. Wallmark

1979-01-01

196

An Accurate Subdomain Model for Magnetic Field Computation in Slotted Surface-Mounted Permanent-Magnet Machines  

Microsoft Academic Search

The paper presents an accurate analytical subdomain model for computation of the open-circuit magnetic field in surface-mounted permanent-magnet machines with any pole and slot combinations, including fractional slot machines, accounting for stator slotting effect. It is derived by solving the field governing equations in each simple and regular subdomain, i.e., magnet, air-gap and stator slots, and applying the boundary conditions

Z. Q. Zhu; L. J. Wu; Z. P. Xia

2010-01-01

197

Effect of surrounding air region size on finite element modeling for permanent magnetic solenoids  

NASA Astrophysics Data System (ADS)

Magnetostatic finite element modeling of permanent magnetic devices can provide accurate results only if the underlying physics is well captured in the model. A single device surrounded by an air padding region is the focus of this research. In the ideal modeling case, this padding region would be infinite in extent. Since an infinite padding region is impossible to implement, the padding sizes in modeling a permanent magnetic solenoid that can ensure accurate results were analyzed in our study. The relationship between accuracy of the simulation result and the surrounding air padding percentage in terms of the device size is demonstrated in this paper, which shows that physically impossible results can occur for a permanent magnetic solenoid if an insufficient padding percentage is used. Design engineers typically use padding percentages from 40 - 400%, and our results show that the required padding percentage depends on the openness of the magnetic circuit. A permanent magnetic solenoid may have more or less openness of the magnetic circuit when the magnetic vector of the side magnets has a larger or smaller angle ?1. For a more open magnetic circuit with ?1 near 90°, a higher padding percentage, up to 600%, is required. For a less open magnetic circuit with ?1 <= 30°, 200% padding is recommended for better accuracy.

Chen, C. H.; Lin, S.; Horwath, J. C.; Hoff, B. W.; Haworth, M. D.; Heidger, S. L.

2011-04-01

198

Fuzzy modeling and synchronization of different memristor-based chaotic circuits  

NASA Astrophysics Data System (ADS)

This Letter is concerned with the problem of fuzzy modeling and synchronization of memristor-based Lorenz circuits with memristor-based Chua's circuits. In this Letter, a memristor-based Lorenz circuit is set up, and illustrated by phase portraits and Lyapunov exponents. Furthermore, a new fuzzy model of memristor-based Lorenz circuit is presented to simulate and synchronize with the memristor-based Chua's circuit. Through this new fuzzy model, two main advantages can be obtained as: (1) only two linear subsystems are needed; (2) fuzzy synchronization of these two different chaotic circuits with different numbers of nonlinear terms can be achieved with only two sets of gain K. Finally, numerical simulations are used to illustrate the effectiveness of these obtained results.

Wen, Shiping; Zeng, Zhigang; Huang, Tingwen; Chen, Yiran

2013-11-01

199

Probabilistic Modeling of QCA Circuits Using Bayesian Networks  

Microsoft Academic Search

To push the frontiers of quantum-dot cellar automata (QCA) based circuit design, it is necessary to have design and analysis tools at multiple levels of abstractions. To characterize the performance of QCA circuits it is not sufficient to specify just the binary discrete states (0 or 1) of the individual cells, but also the probabilities of observing these states. We

Sanjukta Bhanja; Sudeep Sarkar

2006-01-01

200

Modeling a Verification Test System for Mixed-Signal Circuits  

Microsoft Academic Search

In contrast to the large number of logic gates and storage circuits encountered in digital networks, purely analog networks usually have relatively few circuit primitives (operational amplifiers and so on). The complexity lies not in the number of building blocks but in the complexity of each block and the need to test a range of parameters-for example, gain, bandwidth, and

David San Segundo Bello; Ronald J. W. T. Tangelder; Hans G. Kerkhoff

2001-01-01

201

Creating dynamic equivalent PV circuit models with impedance spectroscopy for arc-fault modeling.  

SciTech Connect

Article 690.11 in the 2011 National Electrical Code{reg_sign} (NEC{reg_sign}) requires new photovoltaic (PV) systems on or penetrating a building to include a listed arc fault protection device. Currently there is little experimental or empirical research into the behavior of the arcing frequencies through PV components despite the potential for modules and other PV components to filter or attenuate arcing signatures that could render the arc detector ineffective. To model AC arcing signal propagation along PV strings, the well-studied DC diode models were found to inadequately capture the behavior of high frequency arcing signals. Instead dynamic equivalent circuit models of PV modules were required to describe the impedance for alternating currents in modules. The nonlinearities present in PV cells resulting from irradiance, temperature, frequency, and bias voltage variations make modeling these systems challenging. Linearized dynamic equivalent circuits were created for multiple PV module manufacturers and module technologies. The equivalent resistances and capacitances for the modules were determined using impedance spectroscopy with no bias voltage and no irradiance. The equivalent circuit model was employed to evaluate modules having irradiance conditions that could not be measured directly with the instrumentation. Although there was a wide range of circuit component values, the complex impedance model does not predict filtering of arc fault frequencies in PV strings for any irradiance level. Experimental results with no irradiance agree with the model and show nearly no attenuation for 1 Hz to 100 kHz input frequencies.

Johnson, Jay Dean; Kuszmaul, Scott S.; Strauch, Jason E.; Schoenwald, David Alan

2011-06-01

202

Modeling and Design Considerations for Substrate Integrated Waveguide Circuits and Components  

Microsoft Academic Search

This paper presents an overview of the recent achievements in the held of substrate integrated waveguides (SIW) technology, with particular emphasis on the modeling strategy and design considerations of millimeter-wave integrated circuits as well as the physical interpretation of the operation principles and loss mechanisms of these structures. The most common numerical methods for modeling both SIW interconnects and circuits

Maurizio Bozzi; Feng Xu; Dominic Deslandes; Ke Wu

2007-01-01

203

Quasi-Static Derived Physically Expressive Circuit Model for Lossy Integrated RF Passives  

Microsoft Academic Search

This paper presents a novel approach for deriving a physically meaningful circuit model for integrated RF lossy passives such as spiral inductors on a silicon substrate. The approach starts from a quasi-static partial element equivalent circuit (PEEC) model. The concept of complex inductance and capacitance is introduced to uniformly deal with the conductor and dielectric losses. Basic Y- Delta network

Hai Hu; Kai Yang; Ke-Li Wu; Wen-Yan Yin

2008-01-01

204

Overview of modelling and analysis techniques for arbiters and related circuits  

Microsoft Academic Search

1. Abstract This is an attempt t o give a n overview of the state of affairs in the literature of the modelling and analysis techniques for arbiters and related flip-flop based circuits. Efforts are especially concentrated on the lower level modelling and analysis of simple circuits using analogue dynamic systems techniques. The phenomenon known as metastability is given particular

Fei Xia; Alex Yakovlev

1998-01-01

205

Dynamic models and model validation for PEM fuel cells using electrical circuits  

Microsoft Academic Search

This paper presents the development of dynamic models for proton exchange membrane (PEM) fuel cells using electrical circuits. The models have been implemented in MATLAB\\/SIMULINK and PSPICE environments. Both the double-layer charging effect and the thermodynamic characteristic inside the fuel cell are included in the models. The model responses obtained at steady-state and transient conditions are validated by experimental data

Caisheng Wang; M. Hashem Nehrir; Steven R. Shaw

2005-01-01

206

Analysis, circuit modeling, and optimization of mushroom waveguide photodetector (mushroom-WGPD)  

Microsoft Academic Search

The waveguide photodetector (WGPD) is considered a leading candidate to overcome the bandwidth\\/quantum-efficiency tradeoff in conventional photodetectors (PDs). To overcome the tradeoff between the capacitance and contact resistance, the mushroom-WGPD was proposed. A calibrated circuit model for mushroom-WGPD, including all parasitics, is presented so that a complete circuit simulation of the entire photoreceiver circuit with WGPD now becomes feasible. Both

Yasser M. El-Batawy; M. Jamal Deen

2005-01-01

207

Analysis, Circuit Modeling,and Optimization of Mushroom Waveguide Photodetector (Mushroom-WGPD)  

Microsoft Academic Search

The waveguide photodetector (WGPD) is considered a leading candidate to overcome the bandwidth\\/quantum-efficiency tradeoff in conventional photodetectors (PDs). To overcome the tradeoff between the capacitance and contact resistance,the mushroom-WGPD was proposed. In this paper, a calibrated circuit model for mushroom-WGPD, including all parasitics, is presented so that a complete circuit simulation of the entire photoreceiver circuit with WGPD now becomes

Yasser M. El-Batawy; M. Jamal Deen

2005-01-01

208

Simplified Transmission Line Models for Use with Computer-Aided Circuit/System Analysis Programs.  

National Technical Information Service (NTIS)

Two distinct but complimentary techniques for modeling multiconductor transmission lines for use with the SCEPTRE computer program are presented. The transmission line models developed can be modified for compatibility with other circuit/system transient ...

J. I. Lubell

1973-01-01

209

Evaluation and Validation of Equivalent Circuit Photovoltaic Solar Cell Performance Models.  

National Technical Information Service (NTIS)

The five-parameter model is a performance model for photovoltaic solar cells that predicts the voltage and current output by representing the cells as an equivalent electrical circuit with radiation and temperature-dependent components. An important featu...

B. P. Dougherty D. T. Reindl M. T. Boyd S. A. Klein

2011-01-01

210

Equivalent-Circuit Model for High-Capacitance MLCC Based on Transmission-Line Theory  

Microsoft Academic Search

This paper provides a modeling methodology for high-capacitance multilayer ceramic capacitors (MLCCs) based on the transmission-line theory. To model the high-capacitance MLCC comprised of hundreds of thin layers, a distributed equivalent circuit is modified to a transmission-line circuit. Simpler models for MLCCs are demonstrated using a continued fractions approximation from the transmission-line input impedance equation. A second-order model predicts MLCC

Myoung-Gyun Kim; Byoung Hwa Lee; Tae-Yeoul Yun

2012-01-01

211

A novel double-circuit-rotor balanced induction motor for improved slip-energy recovery drive performance. Part 1: Modeling and simulation  

SciTech Connect

A new construction for the rotor windings of balanced wound-rotor induction motors employed in the slip-energy recovery drives is proposed, in this paper, to reduce the time harmonics which are commonly generated in the machine. The propose machine has a double-circuit in the rotor. One circuit is star connected while the other is delta connected. Each of these two circuits is connected to a diode-bride rectifier to achieve a twelve-pulse operation characteristics. The main objective of this paper is to develop a new model which is capable of simulating the proposed machine, neglecting nonlinearities due to magnetic saturation, and its associated converters. Such a model is further complicated due to the presence of the two rotor circuits and their mutual interaction.

Zakaria, W.S. [United Arab Emirates Univ., El-Ain (United Arab Emirates); Alwash, S.R. [Jordan Univ. of Science and Technology, Irbid (Jordan); Shaltout, A.A. [Cairo Univ. (Egypt)

1996-09-01

212

Modeling and Dynamic Simulation of IC Engine Driven Permanent Magnet Generator Using Matlab\\/Simulink for Hybrid Tracked Vehicle  

Microsoft Academic Search

A simple dynamic model is needed to study the dynamic behavior of IC engine driven permanent magnet generator, which is used in hybrid tracked vehicle. The simple mathematical model for the typical engine is developed using look-up table obtained from actual test bed results and physical equations. Permanent magnet generator model is developed by dq equivalent circuit model approach for

U. Shanmuganathan; R. Govarthanan; A. Muthumailvaganan; A. Imayakumar

2006-01-01

213

[Modeling and analysis of volume conduction based on field-circuit coupling].  

PubMed

Numerical simulations of volume conduction can be used to analyze the process of energy transfer and explore the effects of some physical factors on energy transfer efficiency. We analyzed the 3D quasi-static electric field by the finite element method, and developed A 3D coupled field-circuit model of volume conduction basing on the coupling between the circuit and the electric field. The model includes a circuit simulation of the volume conduction to provide direct theoretical guidance for energy transfer optimization design. A field-circuit coupling model with circular cylinder electrodes was established on the platform of the software FEM3.5. Based on this, the effects of electrode cross section area, electrode distance and circuit parameters on the performance of volume conduction system were obtained, which provided a basis for optimized design of energy transfer efficiency. PMID:23016401

Tang, Zhide; Liu, Hailong; Xie, Xiaohui; Chen, Xiufa; Hou, Deming

2012-08-01

214

Transient analysis of microwave active circuits based on time-domain characteristic models  

Microsoft Academic Search

A modular method is presented to speed up transient simulation of microwave active circuits which consist of linear components and active devices that are often nonlinear. Firstly, the linear components and active devices are individually characterized by time-domain characteristic models (TDCM's) and lumped equivalent circuits, respectively, to reduce the computer memory. Then, based on deconvolution, the TDCM's of linear components

Qing-Xin Chu; Yuen-Pat Lau; Fung-Yuel Chang

1998-01-01

215

A General Power Model of Differential Power Analysis Attacks to Static Logic Circuits  

Microsoft Academic Search

This paper discusses a general model of differential power analysis (DPA) attacks to static logic circuits. Focusing on symmetric-key cryptographic algorithms, the proposed analysis provides a deeper insight into the vulnerability of cryptographic circuits. The main parameters that are of interest in practical DPA attacks are derived under suitable approximations, and a new figure of merit to measure the DPA

Massimo Alioto; Massimo Poli; Santina Rocchi

2010-01-01

216

An Equivalent Circuit Modeling of an Equispaced Metallic Nanoparticles (MNPs) Plasmon Wire  

Microsoft Academic Search

Based on the electric dipole moment (EDM) model of free oscillating electrons inside a single metallic nanoparticle (MNP), a comprehensive methodology is presented in the paper for calculating the equivalent circuit elements associated with an MNP. To find out the passive circuit elements for the MNP, the electromagnetic (EM) power flows are calculated by deriving the relaxation damping, radiation outflow,

Kyungjun Song; Pinaki Mazumder

2009-01-01

217

Analysis of circuit model for vertical-cavity surface-emitting lasers  

NASA Astrophysics Data System (ADS)

Circuit model is presented by considering carriers transportation behavior in SCH region and analyzing rate-equations of vertical-cavity surface emitting lasers. The frequency response characteristics are given by circuit simulation and we discuss and compare the result with practical device.

Wu, Wenguang

2008-03-01

218

On Limitations and Extensions of STG Model for Designing Asynchronous Control Circuits  

Microsoft Academic Search

A number of limitations of the current status of signal transition graphs (STGs), a model which has recently become popular for designing asynchronous interface circuits, are discussed. The major syntactic and semantic restrictions that can be lifted are safety, free-choice net structure and binary signal labeling. A number of instructive examples of interface control circuit specifications, which are semantically correct

Alexandre Yakovlev

1992-01-01

219

A universal model for lossy and dispersive transmission lines for time domain CAD of circuits  

Microsoft Academic Search

A universal equivalent circuit for lossy and dispersive transmission lines is presented. Existing CAD (computer-aided design) packages, such as SPICE, can be used for its implementation. The starting points for obtaining the models are the analog filters which approximate the forward impulse response and characteristic impedance. The equivalent circuit is used to simulate the effects of pulse propagation on microstrip

Jost I. Alonso; Josd Borja; F. Perez

1991-01-01

220

Statistical Constrained Optimization of Analog CMOS Circuits using Empirical Performance Models  

Microsoft Academic Search

In this paper, we present a statistical constrained CAD-compatible optimization algorithm for analog MOS integrated circuit design. The algorithm uses design of experiments (DOE), together with the response surface methodology (RSM), to determine simple empirical models relating circuit performances to device sizes. It then applies the Lagrange multiplier method to solve the resulting statistical constrained nonlinear optimization problem. The algorithm

Hua Su; Christopher Michael; Mohammed Ismail

1994-01-01

221

High-Accuracy Emission Simulation Models for VLSI Chips including Package and Printed Circuit Board  

Microsoft Academic Search

The electromagnetic emission of complex very large scale integrated circuits is determined by their operation activity plus the manifold noise propagation paths through the on-chip power routing, the package traces and the planes and traces on the printed circuit board. The design of any emission test board influences the emission finally measured at defined probing connectors. Good simulation models have

Thomas Steinecke; Mehmet Goekcen; Dirk Hesidenz; Andreas Gstoettner

2007-01-01

222

Analytical modeling of device-circuit interactions for the power insulated gate bipolar transistor (IGBT)  

Microsoft Academic Search

The device-circuit interactions of the power insulated gate bipolar transistor (IGBT) for a series resistor-inductor load, both with and without a snubber, are simulated. An analytical model for the transient operation of the IGBT, previously developed, is used in conjunction with the load circuit state equations for the simulations. The simulated results are compared with experimental results for all conditions.

1990-01-01

223

Dynamic modeling of permanent magnet synchronous machines using direct-coupled time stepping finite element method  

Microsoft Academic Search

A dynamic model of permanent magnet synchronous machines using the finite element method is presented. The system equations, which are based directly on the coupled finite element equations of the magnetic field, the stator circuit equations and the torque equation, are solved by using time stepping method. The major feature in the study is that the classic concept of the

S. L. Ho; H. L. Li

1999-01-01

224

Energy considerations in vector magnetization models  

Microsoft Academic Search

Scalar magnetization model energy calculations, which are useful in calculating energy losses in open magnetization processes, are extended here to vector models. The energy loss is calculated as the difference between the energy input to the magnetic medium and the change in energy stored in the locally reversible component of the total magnetization. It is shown that under rotating magnetizing

Edward Dellatorre; Ann Reimers

2001-01-01

225

Fluid modeling of magnetized plasmas  

SciTech Connect

The simplified description given by fluid models of magnetized plasmas makes it possible to simulate large scale problems such as the interaction of the solar wind with the earth's magnetic field. However, the accurate numerical solution of the fluid equations is made more difficult by the singular nature of the flow when magnetic reconnection occurs. During substorms, for example, details of small features of the flow in the magnetotail appear to cause changes in the global solutions. New methods for treating singular problems have been developed. Some of these are reviewed, including adaptive meshes and other tricks taken from calculations. Several illustrative problems are described. 16 references, 6 figures.

Brackbill, J.U.

1985-01-01

226

Characteristics and computer model simulation of magnetic damping forces in maglev systems  

SciTech Connect

This report discusses the magnetic damping force in electrodynamic suspension (EDS) maglev systems. The computer model simulations, which combine electrical system equations with mechanical motion equations on the basis of dynamic circuit theory, were conducted for a loop-shaped coil guideway. The intrinsic damping characteristics of the EDS-type guideway are investigated, and the negative damping phenomenon is confirmed by the computer simulations. The report also presents a simple circuit model to aid in understanding damping-force characteristics.

He, J.L.; Rote, D.M.; Chen, S.S.

1994-05-01

227

Improved lumped-pi circuit model for bulk current injection probes  

Microsoft Academic Search

In this work, a lumped-parameter circuit model of injection probes for bulk current injection (BCI) is derived and discussed. The model is extracted from scattering parameter experimental measurements carried out with the probe mounted on an ad hoc calibration fixture, ideally working as an electrically-short transmission line. A circuit model of the overall calibration fixture is used to de-embed setup-related

F. Grassi; S. A. Pignari; F. Marliani

2005-01-01

228

Time-delay circuit model of high-speed p-i-n photodiodes  

Microsoft Academic Search

We have proposed an equivalent electric circuit model of p-i-n photodiode including the transit-time effect for performance evaluation of optical systems through the aid of a SPICE-like circuit simulator. No model-dependent close-form expression is necessary in our model. Its validity is shown for the analysis of frequency response in simplified p-i-n photodiodes with different lengths of i-region under uniform or

Jau-Ji Jou; Cheng-Kuang Liu; Chien-Mei Hsiao; Huang-Hsiang Lin; Hsiu-Chih Lee

2002-01-01

229

Nano-magnetic non-volatile CMOS circuits for nano-scale FPGAs (abstract only)  

Microsoft Academic Search

Nanotechnology promises to open up new ways of scaling CMOS circuits by introducing new materials. For example, a hybrid circuit of CMOS gates and carbon nano-tubes (CNT), NEMS relay logic and emerging memory devices have been proposed for future nano-scale Field Programmable Gate Arrays (FPGAs). Hybrid circuits for use as FPGA configurable logic blocks (CLBs) are often proposed in the

Larkhoon Leem; James A. Weaver; Metha Jeeradit; James S. Harris

2010-01-01

230

Single-pass beam measurements for the verification of the LHC magnetic model  

SciTech Connect

During the 2009 LHC injection tests, the polarities and effects of specific quadrupole and higher-order magnetic circuits were investigated. A set of magnet circuits had been selected for detailed investigation based on a number of criteria. On or off-momentum difference trajectories launched via appropriate orbit correctors for varying strength settings of the magnet circuits under study - e.g. main, trim and skew quadrupoles; sextupole families and spool piece correctors; skew sextupoles, octupoles - were compared with predictions from various optics models. These comparisons allowed confirming or updating the relative polarity conventions used in the optics model and the accelerator control system, as well as verifying the correct powering and assignment of magnet families. Results from measurements in several LHC sectors are presented.

Calaga, R.; Giovannozzi, M.; Redaelli, S.; Sun, Y.; Tomas, R.; Venturini-Delsolaro, W.; Zimmermann, F.

2010-05-23

231

Transcutaneous Battery Recharging By Volume Conduction and its Circuit Modeling  

Microsoft Academic Search

Many implantable devices require large capacity batteries implanted in the body. Transcutaneous battery recharging can effectively maintain the longevity of these implants. Based on this consideration we have developed a transcutaneous battery recharging circuit unit which takes advantages of skin volume conduction. This unit is able to pass 2.8 mA from the outside to the inside of pig skin with

Zhide Tang; R. J. Sclabassi; C. Sun; S. A. Hackworth; Jun Zhao; X. T. Cui; M. Sun

2006-01-01

232

Finite element modeling of printed circuit board for structural analysis  

Microsoft Academic Search

Printed circuit boards with unfavourable deflection have been considered for better mechanical design. During the reflow process, the PCB has experienced a temperature range between ambient temperature and peak furnace temperature. Out of plane deflection is generated due to the thermal properties mismatch of the material composition. The combination of board materials and copper plating is researched for investigation of

M. Lee

1997-01-01

233

Transient temperature measurements and modeling of IGBT's under short circuit  

Microsoft Academic Search

This paper discusses the estimation of possible device destruction inside power converters in order to predict failures by means of simulation. The study of insulated gate bipolar transistor (IGBT) thermal destruction under short circuits is investigated. An easy experimental method is presented to estimate the temperature decay in the device from the saturation current response at low gate-to-source voltage during

Anis Ammous; Bruno Allard; Herve Morel

1998-01-01

234

Modeling and sizing for minimum energy operation in subthreshold circuits  

Microsoft Academic Search

This paper examines energy minimization for circuits operating in the subthreshold region. Subthreshold operation is emerging as an energy-saving approach to many energy-con- strained applications where processor speed is less important. In this paper, we solve equations for total energy to provide an analytical solution for the optimum and to minimize energy for a given frequency in subthreshold operation. We

Benton H. Calhoun; Alice Wang; Anantha Chandrakasan

2005-01-01

235

Note: Radio frequency inductance-capacitance band-stop filter circuit to perform contactless conductivity measurements in pulsed magnetic fields  

NASA Astrophysics Data System (ADS)

We present a new technique to perform radio frequency (rf) contactless conductivity measurements in pulsed magnetic fields to probe different ground states in condensed matter physics. The new method utilizes a simple analog band-stop filter circuit implemented in a radio frequency transmission setup to perform contactless conductivity measurements. The new method is more sensitive than the other methods (e.g., the tunnel diode oscillator and the proximity detector oscillator) due to more sensitive dependence of the circuit resonance frequency on the tank circuit inductance (not the transmission line). More important, the new method is more robust than other methods when used to perform measurements in very high magnetic fields, works for a wide range of temperatures (i.e., 300 K-1.4 K) and is less sensitive to noise and mechanical vibrations during pulse magnet operation. The new technique was successfully applied to measure the Shubnikov-de Haas effect in Bi2Se3 in pulsed magnetic fields of up to 60 T.

Altarawneh, M. M.

2012-09-01

236

Efficient Modeling of Interconnects and Capacitive Discontinuities in High-Speed Digital Circuits.  

National Technical Information Service (NTIS)

Modeling of interconnects and associated discontinuities with the recent advances high-speed digital circuits has gained a considerable interest over the last decade although the theoretical bases for analyzing these structures were well-established as ea...

J. Schutt-aine K. S. Oh

1995-01-01

237

Exploring the low frequency performance of thermal converters using circuit models and a digitally synthesized source  

Microsoft Academic Search

Low-frequency tracking errors of thermal voltage converters are described and estimated using circuit models. A digitally synthesized source is used to confirm ac-dc differences in the 0.001 Hz to 40 Hz range

N. Oldham; M. Parker; B. Bell; S. Avramov-Zamurovic

1996-01-01

238

Development of a Noise Intrinsic Equivalent Circuit Model Using Experimental and Numerical Techniques.  

National Technical Information Service (NTIS)

Noise equivalent circuit models in gallium nitride high electron mobility transistors have been developed using both experimental and numerical approaches. This work serves two primary purposes, to guide device development by establishing the primary caus...

K. J. Webb

2005-01-01

239

Modeling of the radon exhalation from water to air by a hybrid electrical circuit  

Microsoft Academic Search

A new model based on electric circuit theory has been introduced for modeling the radon exhalation from water to air in a\\u000a sample bottle. Comparing the differential equations for radon exhalation from water to air and a hybrid electrical circuit\\u000a shown that the volume of water or air, radon concentration, radon flux and solubility coefficient (dependent on temperature\\u000a of water)

S. M. Musavi Nasab; A. Negarestani; S. Mohammadi

2011-01-01

240

Transient Model Using Cascaded Ideal Transmission Lines for UWB Antennas for Co-simulation with Circuits  

Microsoft Academic Search

An effective and accurate model is presented for co-simulation of circuits and UWB antennas in the time-domain, which can be used in SPICE simulators. An arbitrary UWB antenna is represented by cascaded ideal transmission lines characterized by S-parameter data. Using this model, we can efficiently simulate the entire system of circuits and UWB antennas, together, for transient analysis. Numerical analysis

Zhiguo Su; T. J. Brazil

2007-01-01

241

Magnetic Field from Loops Model  

NSDL National Science Digital Library

The EJSMagnetic Field from Loops model computes the B-field created by an electric current through a straight wire, a closed loop, and a solenoid. Users can adjust the vertical position of the slice through the 3D field. The Magnetic Field from Loops model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ntnu_MagneticFielfFromLoops.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for classical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang; Hwang, Fu-Kwun

2008-11-17

242

A convenient circuit model for millimeter-wave substrate integrated waveguide (SIW) corporate feed for dielectric resonator antenna arrays  

Microsoft Academic Search

In this paper, a generic simple circuit model for 1 x M SlW-parallelfed DRA linear array is presented as a fast method for the analysis and optimization of the larger arrays. This circuit model provides good estimates for the antenna return loss and radiation pattern characteristics. It is based on N-port circuit analysis of the antenna system.

Wael M. Abdel Wahab; S. Safavi-Naeini; D. Busuioc

2010-01-01

243

4th Grade Students Investigate Electric Circuits Through Construction and Illustration  

NSDL National Science Digital Library

As an activity related to FOSS unit Magnetism and Electricity, 4th grade science students use a computer download to explore electrical circuits and to generate illustrations of electrical circuits for physical models built in class

244

Modeling and fabrication of tuned circuits for optical meta-materials  

NASA Astrophysics Data System (ADS)

Recently there has been a drive to create artificial optical materials, or meta-materials, with a specified electrical permittivity and magnetic permeability at optical frequencies. Control over these properties can give rise to new physical phenomena, such as a negative refractive index and "super lensing", with potential applications in nanophotonic systems and nanolithography. Because most materials do not exhibit magnetic behaviour at optical frequencies, control over the effective magnetic permeability is achieved using patterned metal structures much smaller than the wavelength of light. The electric currents induced in the structures produce magnetic fields that may be in phase or may oppose the magnetic field of the incident light. When combined with dielectric materials, these structuresform coupled inductor-capacitor (LC) circuits that can resonate at frequencies in the optical spectrum. Since the resonant properties of the LC circuits control the properties of the meta-material, it is important to understand how changes in shape, size and the position of the subwavelength components affect the resonances. Using the Finite Difference Time Domain (FDTD) method, we study a number of different inductor-capacitor configurations. By applying the concepts of lumped impedance to the electromagnetic fields, the resonant frequencies and Q factors of the tuned optical circuits are determined from the FDTD data. Our in-house electron beam lithography system has been used to fabricate some of the structures. Results of the simulations, the nano-fabrication process and experiments on the meta-materials will be presented.

Davis, T. J.

2006-01-01

245

Modeling QCA Defects at Molecular-level in Combinational Circuits  

Microsoft Academic Search

This paper analyzes the deposition defects in devices and circuits made of quantum-dot cellular automata (QCA) for molecular implementation. Differently from metal-based QCA, in this type of implementation a defect may occur due to the erroneous deposition of cells (made of molecules) on a substrate, i.e. no cell, or an additional cell is placed either near, or within the layout

Mariam Momenzadeh; Marco Ottavi; Fabrizio Lombardi

2005-01-01

246

A fault-tolerant permanent magnet synchronous motor drive with integrated voltage source inverter open-circuit faults diagnosis  

Microsoft Academic Search

This paper presents a variable speed ac drive based on a permanent magnet synchronous motor, supplied by a three-phase fault-tolerant power converter. In order to achieve this, beyond the main routines, the control system integrates a reliable and simple algorithm for real-time diagnostics of inverter open-circuit faults. This algorithm performs an important role since it is able to detect an

Jorge O. Estima; A. J. Marques Cardoso

2011-01-01

247

Equivalent-circuit model for vacuum ultraviolet irradiation of dielectric films  

SciTech Connect

Vacuum ultraviolet (VUV) irradiation, which occurs during plasma processing, causes photoemission of electrons from the dielectrics. Photoemission primarily occurs from defect states in the band gap of the dielectric and results in trapped positive charges. The trapped positive charges are negated by photoinjection of electrons from the underlying substrate into the dielectric. The authors propose an equivalent-circuit model using with which, once the circuit parameters are determined, charging of dielectric materials under VUV irradiation can be predicted. The circuit includes a dielectric capacitor, the intrinsic and photo conductivities of the dielectric and substrate, and the processes of photoemission and photoinjection.

Sinha, Harsh; Shohet, J. Leon [Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2012-05-15

248

Current Sensor Modeling With A FE-Tuned MEC: Parameters Identification Protocol  

Microsoft Academic Search

This paper presents a magnetic circuit modeling of closed loop Hall-effect current sensors based on a magnetic equivalent circuit which could be simulated with a circuit type simulation software (PSPICE model). First, the principle of measurement of the closed loop Hall-effect current sensors is described, then, the magnetic equivalent circuit (MEC) modeling justified by the engineers' model needs is elaborated.

F. Sixdenier; M. A. Raulet

2012-01-01

249

Simulink Modeling for Circuit Representation of Granular Chains  

NASA Astrophysics Data System (ADS)

After a review of the coupled Newton's equations for a small alignment of grains with a fixed reflecting end wall, the equations are put into block diagrams of Simulink. Simulink simulations are given for 6 grain systems for cubic and Hertz intergrain potentials. The expected granular solitary waves are seen in the simulations. The block diagrams hence convert a single impulse into a traveling energy bundle of fixed width. This work forms the necessary first step for the eventual realization of the mathematical system represented by the granular chain as a Very Large Scale Integrated (VLSI) circuit.

Sellami, Louiza; Newcomb, Robert W.; Sen, Surajit

2013-05-01

250

Impedance generalization for plasmonic waveguides beyond the lumped circuit model  

NASA Astrophysics Data System (ADS)

We analytically derive a rigorous expression for the relative impedance ratio between two photonic structures based on their electromagnetic interaction. Our approach generalizes the physical meaning of the impedance to a measure for the reciprocity-based overlap of eigenmodes. The consistency with known cases in the radio-frequency and optical domain is shown. The analysis reveals where the applicability of simple circuit parameters ends and how the impedance can be interpreted beyond this point. We illustrate our approach by successfully describing a Bragg reflector that terminates an insulator-metal-insulator plasmonic waveguide in the near infrared by our impedance concept.

Kaiser, Thomas; Hasan, Shakeeb Bin; Paul, Thomas; Pertsch, Thomas; Rockstuhl, Carsten

2013-07-01

251

Improved equivalent circuit and analytical model for amorphous silicon solar cells and modules  

Microsoft Academic Search

An improved equivalent circuit for hydrogenated amorphous silicon (a-Si:H) solar cells and modules is presented. It is based on the classic combination of a diode with an exponential current-voltage characteristic, of a photocurrent source plus a new term representing additional recombination losses in the i-layer of the device. This model\\/equivalent circuit matches the I(V) curves of a-Si:H cells over an

J. Merten; J. M. Asensi; C. Voz; A. V. Shah; R. Platz; J. Andreu

1998-01-01

252

Object-Oriented Modeling Of Power-Electronic Circuits Using Dymola  

Microsoft Academic Search

In this paper, a new approach to the object--oriented modelingof power--electronic circuits is demonstrated. It enablesthe user to specify power--electronic circuits convenientlyin an easy--to--use modular fashion, yet generate simulationcode that is efficient in its use, not requiring the introductionof artificial fast time--constants as was the case with many ofthe earlier proposed methodologies. Dymola enables the userto specify models for individual

Hilding Elmqvist; François E. Cellier; Martin Otter

1994-01-01

253

Unified accurate CAD models for RF, microwave and millimeter-wave integrated circuits  

Microsoft Academic Search

Unified CAD-oriented circuit model is proposed and developed for accurate representation of a variety of planar integrated circuits (ICs). It is realized by implementing a so-called “short-open calibration” (SOC) procedure that uniquely calibrates (de-embeds) the results obtained from a full-wave method of moments (MoM) with two calibration standards: short and open elements. Stemming from the concept of TRL calibration in

Ke Wu; Lei Zhu

1999-01-01

254

Frequency-independent equivalent circuit model for ferromagnetic RF integrated inductors  

Microsoft Academic Search

We have proposed a method for identifying a wide-band equivalent circuit model for ferromagnetic radio frequency (RF) integrated inductors. The equivalent circuit parameters have been extracted from measured S-parameters by using a multiobjective simplex method, which sequentially switches three different cost functions, given by the average of error in Y-parameters, Z-parameters, and S-parameters. With this method, the optimization converged to

Kengo Sugahara; Shinji Tanabe; Masahiro Yamaguchi

2005-01-01

255

Impact of multiple scattering on passivity of equivalent-circuit via models  

Microsoft Academic Search

For fast analyses of multilayer printed circuit boards and packages, the parallel-plate impedance (Zpp) is often used in equivalent-circuit via models to describe the current return path for vias traversing a power\\/ground plane pair. Analytical algorithms for the Zpp calculation, such as the radial waveguide method, usually assumes solid planes and neglect the effect of multiple scattering among open via

Xiaomin Duan; Renato Rimolo-Donadio; Sebastian Muller; Ki Jin Han; Xiaoxiong Gu; Young H Kwark; Heinz-Dietrich Bruns; Christian Schuster

2011-01-01

256

Functional Model of Carbon Nanotube Programmable Resistors for Hybrid Nano\\/CMOS Circuit Design  

Microsoft Academic Search

Hybrid Nano (e.g. Nanotube and Nanowire) \\/CMOS circuits combine both the advantages of Nano-devices and CMOS technologies;\\u000a they have thus become the most promising candidates to relax the intrinsic drawbacks of CMOS circuits beyond Moore’s law.\\u000a A functional simulation model for an hybrid Nano\\/CMOS design is presented in this paper. It is based on Optically Gated Carbon\\u000a NanoTube Field Effect

Weisheng Zhao; Guillaume Agnus; Vincent Derycke; Ariana Filoramo; Christian Gamrat; Jean-Philippe Bourgoin

2009-01-01

257

A microwave equivalent circuit model for semiconductor alloy ramp heterostructure diodes  

Microsoft Academic Search

The microwave impedance of a current-rectifying Al(x)Ga(1-x)As ramp heterostructure is measured from 0.1 to 12 GHz over a temperature range of 20 to 300 K. The elements of a small-signal equivalent-circuit model are optimized to fit the experimental impedance data over the full temperature and dc bias ranges. These circuit elements are identified with the physical structures and carrier transport

Gregory B. Tait; Harvey S. Newman

1991-01-01

258

A Spring Mechanism for Hand Closing of Magnetic Power Air Circuit Breakers  

Microsoft Academic Search

Power air circuit breakers cannot be closed safely on energized circuits by direct manual operation because the force and speed required may, in the case of fault current, exceed the strength of the operator. But in some small installations, manual operation is very desirable. A device is here described, which stores manual work in a spring in easy increments and,

R. C. Dickinson; J. D Findley

1951-01-01

259

LARGE SCALE DISTRIBUTED PARAMETER MODEL OF MAIN MAGNET SYSTEM AND FREQUENCY DECOMPOSITION ANALYSIS  

SciTech Connect

Large accelerator main magnet system consists of hundreds, even thousands, of dipole magnets. They are linked together under selected configurations to provide highly uniform dipole fields when powered. Distributed capacitance, insulation resistance, coil resistance, magnet inductance, and coupling inductance of upper and lower pancakes make each magnet a complex network. When all dipole magnets are chained together in a circle, they become a coupled pair of very high order complex ladder networks. In this study, a network of more than thousand inductive, capacitive or resistive elements are used to model an actual system. The circuit is a large-scale network. Its equivalent polynomial form has several hundred degrees. Analysis of this high order circuit and simulation of the response of any or all components is often computationally infeasible. We present methods to use frequency decomposition approach to effectively simulate and analyze magnet configuration and power supply topologies.

ZHANG,W.; MARNERIS, I.; SANDBERG, J.

2007-06-25

260

Low Insertion HVDC Circuit Breaker: Magnetically Pulsed Hybrid Breaker for HVDC Power Distribution Protection  

SciTech Connect

GENI Project: General Atomics is developing a direct current (DC) circuit breaker that could protect the grid from faults 100 times faster than its alternating current (AC) counterparts. Circuit breakers are critical elements in any electrical system. At the grid level, their main function is to isolate parts of the grid where a fault has occurred—such as a downed power line or a transformer explosion—from the rest of the system. DC circuit breakers must interrupt the system during a fault much faster than AC circuit breakers to prevent possible damage to cables, converters and other grid-level components. General Atomics’ high-voltage DC circuit breaker would react in less than 1/1,000th of a second to interrupt current during a fault, preventing potential hazards to people and equipment.

None

2012-01-09

261

Smiplified Model for Parameter Estimation and Circuit Analysis of Inductive-Adder Modulator.  

National Technical Information Service (NTIS)

In this paper, we propose a simplified model for easy estimation of design parameters and quick analysis of inductive adder modulators. Analytical method is used to deduct the simplified circuit model. This model offers an easy way to understand the behav...

C. Pai J. Sandberg W. Eng W. Zhang Y. Tan

2006-01-01

262

MODEL IDENTIFICATION OF THE PRIMARY CIRCUIT AT THE PAKS NUCLEAR POWER PLANT  

Microsoft Academic Search

Based on a simple process model of the primary circuit in physical coordinates, model parameter estimation has been performed on a unit of the Paks Nuclear Power Plant using measured transient data. The dynamic model is hybrid and nonlinear in its parameters and variables, therefore an est i- mation strategy based on the decomposition of the system has been applied.

Csaba Fazekas; Gabor Szederkenyi; Katalin M. Hangos

263

A breakdown model for the bipolar transistor to be used with circuit simulators  

NASA Astrophysics Data System (ADS)

A breakdown model for the output characteristics of the bipolar transistor (bjt) has been developed. The behavioral modeling capability of PSPICE, a popular SPICE program (with emphasis on integrated circuits) was used to implement the macromodel. The model predicts bjt output characteristics under breakdown conditions. Experimental data was obtained to verify the macromodel. Good agreement exists between the measured and the simulated results.

Keshavarz, A. A.; Raney, C. W.; Campbell, D. C.

264

Electrical circuit model for quantifying the proliferation resistance of nuclear fuel cycles  

Microsoft Academic Search

For quantifying the proliferation resistance of nuclear fuel cycles, the proliferation resistance index was modeled in imitation of an electrical circuit and linked with multi-attribute utility theory. As a case study, this model was applied to Korean nuclear fuel cycle alternatives including DUPIC(Direct Use of spent PWR fuel In CANDU) fuel cycle. The main features of the model are that

Kun Jai Lee

2000-01-01

265

GaAs FET large-signal model and its application to circuit designs  

Microsoft Academic Search

A large-signal GaAs FET model is derived based on dc characteristics of the device. Analytical expressions of modeled nonlinear elements are presented in a form convenient for circuit design. Power saturation and gain characteristics of a GaAs FET are studied theoretically and experimentally. An oscillator design employing the large-signal model is demonstrated.

Y. Tajima; B. Wrona; K. Mishima

1981-01-01

266

A Practical SCR Model for Computer Aided Analysis of AC Resonant Charging Circuits  

Microsoft Academic Search

The SPICE2 SCR MODEL by C. Hu and W. Ki [1] is modified to better simulate the SCR turnoff transient while maintaining the practicality of using only data sheet specifications to determine model parameters. The modified SCR model is used to do SPICE2 simulation of ac resonant charging circuits for pulse power applications.

Roger L. Avant; Fred C. Y. Lee; Dan Y. Chen

1982-01-01

267

Hybrid modeling of woven fibre reinforced metal matrix composite for multilayer circuit boards  

Microsoft Academic Search

Purpose – To present a method to model woven fibre reinforced metal matrix composite for multilayer circuit boards. Design\\/methodology\\/approach – This paper presents a hybrid modelling method to model multilayer multimaterial composites with the combination of metallic and woven composite plies. Firstly, 3D unit cells of woven composite are idealized as orthotropic plies, while metallic layers are taken as isotropic

K. H. Low; Yuqi Wang

2008-01-01

268

Physics-Based AlGaAs/GaAs HBT Model for Circuit Simulation.  

National Technical Information Service (NTIS)

A comprehensive single heterojunction AlGaAs/GaAs biploar transistor (HBT) model suited for circuit simulation is presented. The model is based on the de Graff-Kloosterman formalism for the modelling of the bipolar transistors, but addes important heteros...

A. Hovinen P. Kuivainen

1998-01-01

269

Modular, rule-based modeling for the design of eukaryotic synthetic gene circuits  

PubMed Central

Background The modular design of synthetic gene circuits via composable parts (DNA segments) and pools of signal carriers (molecules such as RNA polymerases and ribosomes) has been successfully applied to bacterial systems. However, eukaryotic cells are becoming a preferential host for new synthetic biology applications. Therefore, an accurate description of the intricate network of reactions that take place inside eukaryotic parts and pools is necessary. Rule-based modeling approaches are increasingly used to obtain compact representations of reaction networks in biological systems. However, this approach is intrinsically non-modular and not suitable per se for the description of composable genetic modules. In contrast, the Model Description Language (MDL) adopted by the modeling tool ProMoT is highly modular and it enables a faithful representation of biological parts and pools. Results We developed a computational framework for the design of complex (eukaryotic) gene circuits by generating dynamic models of parts and pools via the joint usage of the BioNetGen rule-based modeling approach and MDL. The framework converts the specification of a part (or pool) structure into rules that serve as inputs for BioNetGen to calculate the part’s species and reactions. The BioNetGen output is translated into an MDL file that gives a complete description of all the reactions that take place inside the part (or pool) together with a proper interface to connect it to other modules in the circuit. In proof-of-principle applications to eukaryotic Boolean circuits with more than ten genes and more than one thousand reactions, our framework yielded proper representations of the circuits’ truth tables. Conclusions For the model-based design of increasingly complex gene circuits, it is critical to achieve exact and systematic representations of the biological processes with minimal effort. Our computational framework provides such a detailed and intuitive way to design new and complex synthetic gene circuits.

2013-01-01

270

Modeling the cosmic-ray-induced soft-error rate in integrated circuits: An overview  

SciTech Connect

This paper is an overview of the concepts and methodologies used to predict soft-error rates (SER) due to cosmic and high-energy particle radiation in integrated circuit chips. The paper emphasizes the need for the SER simulation using the actual chip circuit model which includes device, process, and technology parameters as opposed to using either the discrete device simulation or generic circuit simulation that is commonly employed in SER modeling. Concepts such as funneling, event-by-event simulation, nuclear history files, critical charge, and charge sharing are examined. Also discussed are the relative importance of elastic and inelastic nuclear collisions, rare event statistics, and device vs. circuit simulations. The semi-empirical methodologies used in the aerospace community to arrive at SERs [also referred to as single-event upset (SEU) rates] in integrated circuit chips are reviewed. This paper is one of four in this special issue relating to SER modeling. Together, they provide a comprehensive account of this modeling effort, which has resulted in a unique modeling tool called the Soft-Error Monte Carlo Model, or SEMM.

Srinivasan, G.R.

1996-01-01

271

Motor circuits are required to encode a sensory model for imitative learning.  

PubMed

Premotor circuits help generate imitative behaviors and can be activated during observation of another animal's behavior, leading to speculation that these circuits participate in sensory learning that is important to imitation. Here we tested this idea by focally manipulating the brain activity of juvenile zebra finches, which learn to sing by memorizing and vocally copying the song of an adult tutor. Tutor song-contingent optogenetic or electrical disruption of neural activity in the pupil's song premotor nucleus HVC prevented song copying, indicating that a premotor structure important to the temporal control of birdsong also helps encode the tutor song. In vivo multiphoton imaging and neural manipulations delineated a pathway and a candidate synaptic mechanism through which tutor song information is encoded by premotor circuits. These findings provide evidence that premotor circuits help encode sensory information about the behavioral model before shaping and executing imitative behaviors. PMID:22983208

Roberts, Todd F; Gobes, Sharon M H; Murugan, Malavika; Ölveczky, Bence P; Mooney, Richard

2012-09-16

272

Eddy current modeling and measuring in fast-pulsed resistive magnets  

Microsoft Academic Search

A method for modeling and measuring electromagnetic transients due to eddy currents in fast-pulsed resistive magnets is proposed. In particular, an equivalent-circuit model and a method for time-domain measurements of eddy currents are presented. The measurements are needed for an accurate control of the magnetic field quality to ensure adequate stability and performance of the particle beam in particle accelerators

Pasquale Arpaia; Marco Buzio; Giancarlo Golluccio; Giuseppe Montenero

2010-01-01

273

A General Approach to Sampled-Data Modeling for Power Electronic Circuits  

Microsoft Academic Search

A general sampled-data representation of the dynamics of arbitrary power electronic circuits is proposed to unify existing approaches. It leads, via compact and powerful notation, to disciplined modeling and straightforward derivation of small-signal models that describe perturbations about a nominal cyclic steady state. Its usefulness is further illustrated by considering the representation and analysis of a class of symmetries in

George C. Verghese; Malik E. Elbuluk; John G. Kassakian

1986-01-01

274

Bulk current injection test modeling using an equivalent circuit for 1.8V mobile ICs  

Microsoft Academic Search

This paper shows a novel simulation method for bulk current injection (BCI) tests of I\\/O buffer circuits of mobile system memory. The simulation model consists of BCI probe, directional coupler, PCB, PKG, and IC. The proposed method is based on a behavioural I\\/O buffer model using a pulse generator as an input. A detailed simulation flow is introduced and validated

SangKeun Kwak; JeongMin Jo; SeokSoon Noh; HyeSook Lee; Wansoo Nah; SoYoung Kim

2012-01-01

275

A new equivalent circuit model of IGBT for simulation of current sensors  

Microsoft Academic Search

A new equivalent circuit model for insulated gate bipolar transistor is presented. It takes into account both electron and hole conduction in sensors and is incorporated with SPICE3 for the simulation of three types of current sensors, namely active, bipolar, and MOS sensors. It adopts a multiMOS model to include the doping variation in the MOS body. The results agree

Chia-Hsiung Kao; Chun-Chieh Tseng; Fong-Ming Lee; Z. J. Shen

2005-01-01

276

An efficient modeling and synthesis procedure of asynchronous sequential logic circuits  

Microsoft Academic Search

A model and procedure are developed for synthesizing asynchronous sequential logic circuits (ASLCs). This model represents the functional behavior with a more compact form and the procedure can synthesize them more efficiently than the traditional one. With the identification of edge inputs from the design specification, a set of equations can be generated which describes the functional behavior of the

Jun-Woo Kang; Chin-Long Wey; P. D. Fisher

1992-01-01

277

Delay Modeling of Bipolar ECL/EFL (Emitter-Coupled Logic/Emitter-Follower-Logic) Circuits.  

National Technical Information Service (NTIS)

This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance...

A. T. Yang

1986-01-01

278

MOSFET modeling and parameter extraction for low temperature analog circuit design  

Microsoft Academic Search

SPICE parameters needed for simulation of CMOS readout circuits used in infrared image sensors cooled at low temperature are extracted using a specific MOSFET model based on the EKV 2.6 compact charge model. It is used below 200 K and is very well adapted to analog simulation in weak and moderate inversion regimes. It was successively applied on different CMOS

P. Martin; M. Bucher; C. Enz

2002-01-01

279

Characterization and modeling of RF substrate coupling effects in 3D integrated circuit stacking  

Microsoft Academic Search

This work addresses parasitic substrate coupling effects in 3D integrated circuits due to Through Silicon Vias (TSV). Electrical characterizations have been performed on dedicated test structures in order to extract electrical models of substrate coupling phenomena when RF signals are propagated in TSV. A good compatibility between RF measurements and RF simulations allows validating modeling tools for predictive studies. Next,

E. Eid; T. Lacrevaz; C. Bermond; S. Capraro; J. Roullard; B. Fléchet; L. Cadix; A. Farcy; P. Ancey; F. Calmon; O. Valorge; P. Leduc

2011-01-01

280

Diagnosing and modeling common-mode radiation from printed circuit boards with attached cables  

Microsoft Academic Search

A procedure for diagnosing and modeling radiation from printed circuit boards with attached cables is presented through a case study of a production model electronic control unit. Procedures for determining EMI antennas, IC sources, and mechanisms by which noise is coupled from the IC source to the antenna are suggested

J. L. Drewniak; Fei Sha; T. P. Van Doren; T. H. Hubing; J. Shaw

1995-01-01

281

An information model for a CAM database to support flexible manufacture of printed circuit boards  

Microsoft Academic Search

The author presents key features from an information model for a CAM (computer-aided manufacturing) database that supports flexible manufacture of printed circuit boards and other selected components and products. This model incorporates information from several sources: shop orders, CAD (computer-aided design), bill of materials, and process setup. The essential activities of manufacturing can be subdivided into several information categories. These

Peter T. Whelan

1991-01-01

282

An information model for a CAM data base to support flexible manufacture of printed circuit boards  

Microsoft Academic Search

Key features from an information model for a computer-aided manufacturing (CAM) database that supports flexible manufacture of printed circuit boards and other selected components and products is presented. This model incorporates information from several sources: shop orders, computer-aided design (CAD), bill of materials, and process setup. The essential activities of manufacturing can be subdivided into several information categories. These categories

Peter T. Whelan

1992-01-01

283

Simplified Unbalanced Force Calculation in Switched Reluctance Machines Using Electromagnetic Circuit Model  

Microsoft Academic Search

This paper presents a simplified unbalanced force calculation for switched reluctance machines (SRM) developed based on an electromagnetic circuit model (EMC). Derived from the EMC model, a set of analytical equations for predicting the rotor unbalanced force is achieved as functions of design parameters, which directly provides an intuitive relationship between estimated unbalanced force and design parameters. The accuracy of

N. H. Fuengwarodsakul; B. G. Gu; S. Schroder; R. W. De Doncker; K. Nam

2005-01-01

284

New paradigm of predictive MOSFET and interconnect modeling for early circuit simulation  

Microsoft Academic Search

A new paradigm of predictive MOSFET and interconnect modeling is introduced. This approach is developed to specifically address SPICE compatible parameters for future technology generations. For a given technology node, designers can use default values or directly input L eff, Tok, Vt, Rdsw and interconnect dimensions to instantly obtain a BSIM3v3 customized model for early stages of circuit design and

Yu Cao; Takashi Sato; Michael Orshansky; Dennis Sylvester; Chenming Hu

2000-01-01

285

Power Circuit and Quench Protection for the Pipetron Magnet Transmission Line  

Microsoft Academic Search

A double aperture, superferric magnet powered by a transmission line centrally located within the magnet's iron yoke has been proposed as the lattice magnet for a very large hadron collider (1). The transmission line contains a single superconducting bus carrying 75 kA for a nominal magnetic field of 2 T in each aperture. This paper describes a possible transmission line

K. Koepke; A. Zlobin; W. Foster

286

Caveats in modeling a common motif in genetic circuits  

NASA Astrophysics Data System (ADS)

From a coarse-grained perspective, the motif of a self-activating species, activating a second species that acts as its own repressor, is widely found in biological systems, in particular in genetic systems with inherent oscillatory behavior. Here we consider a specific realization of this motif as a genetic circuit, termed the bistable frustrated unit, in which genes are described as directly producing proteins. Upon an improved resolution in time, we focus on the effect that inherent time scales on the underlying scale can have on the bifurcation patterns on a coarser scale. Time scales are set by the binding and unbinding rates of the transcription factors to the promoter regions of the genes. Depending on the ratio of these rates to the decay times of both proteins, the appropriate averaging procedure for obtaining a coarse-grained description changes and leads to sets of deterministic equations, which considerably differ in their bifurcation structure. In particular, the desired intermediate range of regular limit cycles fades away when the binding rates of genes are not fast as compared to the decay time of the proteins. Our analysis illustrates that the common topology of the widely found motif alone does not imply universal features in the dynamics.

Labavi?, Darka; Nagel, Hannes; Janke, Wolfhard; Meyer-Ortmanns, Hildegard

2013-06-01

287

A new OLED SPICE model for pixel circuit simulation in OLED-on-silicon microdisplay design  

NASA Astrophysics Data System (ADS)

A new equivalent circuit model of organic-light-emitting-diode (OLED) is proposed. As the single-diode model is able to approximate OLED behavior as well as the multiple-diode model, the new model will be built based on it. In order to make sure that the experimental and simulated data are in good agreement, the constant resistor is exchanged for an exponential resistor in the new model. Compared with the measured data and the results of the other two OLED SPICE models, the simulated I—V characteristics of the new model match the measured data much better. This new model can be directly incorporated into an SPICE circuit simulator and presents good accuracy over the whole operating voltage.

Bohua, Zhao; Ran, Huang; Jianhui, Bu; Yinxue, Lü; Yiqi, Wang; Fei, Ma; Guohua, Xie; Zhensong, Zhang; Huan, Du; Jiajun, Luo; Zhengsheng, Han; Yi, Zhao

2012-07-01

288

A Circuit Model for the Measurement of the Streaming Potential in a Rock Sample  

NASA Astrophysics Data System (ADS)

Streaming potential is usually defined under the assumption that the rock sample under consideration is not connected electrically to any external circuit. In this study we investigate experimentally the effect of the external circuit on the measurement of the streaming potential. Cations usually dominate anions in the diffuse layer in the pore canals in a fluid-saturated porous sandstone sample. When a pressure difference is applied to the sample, fluid flows in the pores and causing a convective current due to the cation-dominate motion. With the separation of opposite ions at the two ends, a streaming potential occurs, and results in a conductive current. Those two current will be opposite and equal in value so that the streaming potential does not change. But in any experimental measurement of the streaming potential, the rock sample is not isolated in the circuit. An external circuit is necessary for the measurement of the potential difference at the ends of the sample. This external circuit will divert the flow of charges. This study investigates the effect of the external circuit on the convective current and conductive current in the pores by experiments, and gives an equivalent circuit model for the two currents. We connect an external resistance Rext to the ends of the fluid-saturated rock sample, and measure the potential difference at the ends of the sample . The impedance of the fluid-saturated rock sample Zrock is definite under a given salinity and can be separately measured. The circuit is governed by the following equations, Urock = ZrockIcond, (1) Urock = RextIext, (2) Iconv + Icond +Iext = 0, (3) where Iconv is the convective current, Icond is the conductive current, Iext is the external current and Urock is the potential difference at the ends of the rock sample. From the above three equations, we get - Urock(Zrock + Rext) Iconv = ---Z--R----- . rock ext (4) We repeated the measurement under different external resistance Rext. The computed convective current changes slightly. Thus we conclude that the measurement circuit does not change the convective current, although it changes the conductive current. So the convective current behaves as a constant current source. This conclusion is in consistence with the electrokinetic model, in which the convection current is caused by the cation-dominated fluid flow under pressure difference. We notice that the measured streaming potential is smaller than that without measuring circuit connected to it, unless the external resistance Rext is orders higher than the resistance of the rock. This study is supported by project No.41174110 of the National Natural Science Foundation of China.

Yin, C.; Wang, J.; Qiu, A.; Liu, X.; Hu, H.

2012-04-01

289

A new OLED SPICE model for pixel circuit simulation in OLED-on-silicon microdisplay design  

Microsoft Academic Search

A new equivalent circuit model of organic-light-emitting-diode (OLED) is proposed. As the single-diode model is able to approximate OLED behavior as well as the multiple-diode model, the new model will be built based on it. In order to make sure that the experimental and simulated data are in good agreement, the constant resistor is exchanged for an exponential resistor in

Zhao Bohua; Huang Ran; Bu Jianhui; Lü Yinxue; Wang Yiqi; Ma Fei; Xie Guohua; Zhang Zhensong; Du Huan; LuoJiajun; Han Zhengsheng; Zhao Yi

2012-01-01

290

Physical modeling of temperature dependences of SOI CMOS devices and circuits including self-heating  

Microsoft Academic Search

To simulate and examine temperature and self-heating effects in Silicon-On-Insulator (SOI) devices and circuits, a physical temperature-dependence model is implemented into the SOISPICE fully depleted (FD) and nonfully depleted (NFD) SOI MOSFET models. Due to the physical nature of the device models, the temperature-dependence modeling, which enables a device self-heating option as well, is straightforward and requires no new parameters.

Glenn O. Workman; Jerry G. Fossum; Srinath Krishnan; Mario M. Pelella

1998-01-01

291

Nuclear matter magnetization in the Skyrme model  

NASA Astrophysics Data System (ADS)

The effects of an external magnetic field on the nuclear medium are studied within the Skyrme model of the nuclear interaction. The equation of state, spin polarization, and magnetization are evaluated at zero temperature for both neutron matter and isospin symmetric nuclear matter. We consider the anomalous magnetic moments of the nucleons and the quantization induced by a magnetic field over the proton energy spectrum. A comparison of two versions of the model, allowing or not for spontaneous magnetization, is performed. We cover a range of magnetic-field strengths and matter densities appropriate for astrophysical studies.

Aguirre, R.

2011-05-01

292

Energy considerations in vector magnetization models  

SciTech Connect

Scalar magnetization model energy calculations, which are useful in calculating energy losses in open magnetization processes, are extended here to vector models. The energy loss is calculated as the difference between the energy input to the magnetic medium and the change in energy stored in the locally reversible component of the total magnetization. It is shown that under rotating magnetizing processes, the energy loss decreases as the material is saturated. For smaller rotating fields in anisotropic media, the magnetization lies between the applied field and the easy axis and the energy loss is not constant with rotation even if the magnitude of the field is constant. {copyright} 2001 American Institute of Physics.

DellaTorre, Edward; Reimers, Ann

2001-06-01

293

Nuclear matter magnetization in the Skyrme model  

SciTech Connect

The effects of an external magnetic field on the nuclear medium are studied within the Skyrme model of the nuclear interaction. The equation of state, spin polarization, and magnetization are evaluated at zero temperature for both neutron matter and isospin symmetric nuclear matter. We consider the anomalous magnetic moments of the nucleons and the quantization induced by a magnetic field over the proton energy spectrum. A comparison of two versions of the model, allowing or not for spontaneous magnetization, is performed. We cover a range of magnetic-field strengths and matter densities appropriate for astrophysical studies.

Aguirre, R. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata and IFLP, CCT-La Plata, CONICET (Argentina)

2011-05-15

294

A physical compact model of DG MOSFET for mixed-signal circuit applications- part I: model description  

Microsoft Academic Search

To use double-gate (DG) MOSFET for mixed-signal circuit applications, especially for circuits in which the two gates are independently driven, such as in the case of dynamic-threshold and fixed-potential-plane operations, physical compact models that are valid for all modes of operations are necessary for accurate design and analysis. Employing physically rigorous current-voltage (I-V) relationship in subthreshold and above-threshold regions as

Gen Pei; Weiping Ni; Abhishek V. Kammula; Bradley A. Minch; Edwin Chih-Chuan Kan

2003-01-01

295

2-D lumped-parameter thermal modelling of axial flux permanent magnet generators  

Microsoft Academic Search

Results from lumped parameter thermal modeling of an axial flux permanent magnet generator based on the application of the 2-D equivalent thermal circuit are presented. The components of the generator and the internal air-flow domain are split into a system of connected and interacting control volumes. Energy and mass conservation equations are then solved for each of volume to determine

C. H. Lim; J. R. Bumby; R. G. Dominy; G. I. Ingram; K. Mahkamov; N. L. Brown; A. Mebarki; M. Shanel

2008-01-01

296

Study on dynamic arc model for high voltage hybrid circuit breaker using vacuum interrupter and SF6 interrupter in series  

Microsoft Academic Search

Hybrid circuit breaker, consisting of a vacuum interrupter and an SF6 interrupter in series, which take the place of single SF6 circuit breaker, is a research area to low-carbon technology for high-voltage switch. In this paper, the model simulation system of hybrid circuit breaker was established by Alternative Transients Program. The system simulation model establishment mainly includes building the electromagnetic

Liao Minfu; Cheng Xian; Duan Xiongying; Zou Jiyan

2010-01-01

297

Template-Free Symbolic Performance Modeling of Analog Circuits via Canonical-Form Functions and Genetic Programming  

Microsoft Academic Search

This paper presents CAFFEINE, a method to automatically generate compact interpretable symbolic performance models of analog circuits with no prior specification of an equation template. CAFFEINE uses SPICE simulation data to model arbitrary nonlinear circuits and circuit characteristics. CAFFEINE expressions are canonical-form functions: product-of-sum layers alternating with sum-of-product layers, as defined by a grammar. Multiobjective genetic programming trades off error

Trent McConaghy; Georges G. E. Gielen

2009-01-01

298

Verilog-A modeling of SPAD for circuit simulations  

NASA Astrophysics Data System (ADS)

A behavior mode for simulating single-photon avalanche diodes is presented. The model is developed using Verilog-A description language. The derived model is able to describe the static, the dynamic behavior, the triggering, the self-sustaining and the self-quenching processes, and it also correctly characterizes the reverse current-voltage curve. Simulation results confirmed the validity of the proposed model.

Yang, Hong-jiao; Jin, Xiang-liang; Zhou, Xiao-ya; Chen, Chang-ping; Luo, Jun

2013-08-01

299

Model of shock-wave magnetic cumulation  

NASA Astrophysics Data System (ADS)

A shock-wave magnetic cumulation technique is used to generate a megagauss magnetic field in an aluminium powder under quasi-cylindrical geometry. A magnetohydrodynamic (MHD) model of shock-wave magnetic cumulation is proposed. The model is based on the Oh-Persson equation of state and experimental data on electrical conductivity of powders. The 1D simulation reveals the features of the MHD flow under converging of the cylindrical shock wave. The experimental record of the magnetic field in the generator is in reasonable agreement with simulation results. This fact validates the model and allows one to optimize the cumulation system for producing a higher magnetic field.

Gilev, S. D.

2009-01-01

300

Energy Scavengers : Modeling and Behavior with Different Load Circuits  

Microsoft Academic Search

This contribution describes the modeling of vibration-driven energy scavengers, either based on electrostatic, electromagnetic or piezoelectric principles. Subsequently, the behavior of the scavenger model is tested with two different types of load: a resistive load and a rectifier with a fixed voltage at the output. Optimal power output of the scavenger is calculated for both load-cases. It is shown that

R. D'hulst; T. Sterken; P. Fiorinit; R. Puers; J. Driesen

2007-01-01

301

MOSFET thermal noise modeling for analog integrated circuits  

Microsoft Academic Search

The effects of device geometry, oxide thickness, and bias condition on the thermal noise of MOSFET's are investigated. The experimental results show that the conventional MOSFET thermal noise models do not accurately predict the thermal noise of MOSFET's. A model that is capable of predicting the thermal noise of both long and short channel devices in both the triode and

Bing Wang; James R. Hellums; Charles G. Sodini

1994-01-01

302

MOSFET modeling for analog circuit CAD: problems and prospects  

Microsoft Academic Search

The requirements for good MOSFET modeling are discussed, as they apply to usage in analog and mixed analog-digital design. A set of benchmark tests that can be easily performed by the reader are given, and it is argued that most CAD models today cannot pass all the tests, even for simple, long-channel devices at room temperature. A number of other

Yannis P. Tsividis; Ken Suyama

1994-01-01

303

Middle school students' mental models of magnets and magnetism  

NASA Astrophysics Data System (ADS)

The purpose of this study was to conduct a detailed analysis of students' mental models across three themes related to magnetism: what magnets are, what it means to be magnetized, and how magnetic interactions occur. Mental models are organized collections of conceptions, run in one's mind, to help understand the world (Johnson-Laird, 1983). They also provide the learner a means to organize concepts in a way to help understand the world or to explain it to others (Clement & Sarama, 2004; Harrison & Treagust, 1996). While there has been considerable prior research documenting students' conceptions related to magnetism, the majority of the studies comprising this informative and valuable body of work has been confined to specific concepts at points in time. Comparatively, few studies have examined how students make sense of multiple concepts relating to magnetism and how the sophistication and explanatory power of their mental models comprised of these concepts change with instruction. Using an interpretive research design, the goal here was not to count concepts or individuals' representations of them, but rather to qualitatively search for patterns in representations of students' conceptions and lines of reasoning that are indicative of broader interpretations of experience (Strauss & Corbin, 1998) - students' mental models relating to magnetism. Using a variety of methods of elicitation, including free response items prior to and throughout instruction and semi-structured interviews, I identified five categories of concepts from which students constructed their mental models: (1) material-based properties; (2) two-sidedness; (3) internal features; (4) organization; and (5) external spatial features. Analysis of the representation of concepts among these categories yielded five levels of mental models based on model sophistication and ability to explain magnetic phenomena across diverse contexts. Results suggested that through explicitly scaffolded instruction based on a small number of fundamental principles, 8th grade students were able to construct level-appropriate microscale-based mental models of magnetic phenomena.

Sederberg, David

304

CAD-oriented equivalent-circuit modeling of on-chip interconnects on lossy silicon substrate  

Microsoft Academic Search

A new, comprehensive CAD-oriented modeling methodology for single and coupled interconnects on an Si-SiO2 substrate is presented. The modeling technique uses a modified quasi-static spectral domain electromagnetic analysis which takes into account the skin effect in the semiconducting substrate. Equivalent-circuit models with only ideal lumped elements, representing the broadband characteristics of the interconnects, are extracted. The response of the proposed

Ji Zheng; Yeon-Chang Hahm; Vijai K. Tripathi; Andreas Weisshaar

2000-01-01

305

Efficient kernel functions for support vector machine regression model for analog circuits’ performance evaluation  

Microsoft Academic Search

Support vector machines (SVMs) have been widely used for creating fast and efficient performance macro-models for quickly\\u000a predicting the performance parameters of analog circuits. These models have proved to be not only effective and fast but accurate\\u000a also while predicting the performance. A kernel function is an integral part of SVM to obtain an optimized and accurate model.\\u000a There is

Dharmendar Boolchandani; Abrar Ahmed; Vineet Sahula

2011-01-01

306

New printed circuit boards magnetic coils in the vacuum vessel of J-TEXT tokamak for position measurement  

SciTech Connect

Four sets of magnetic diagnostic coils, which are printed on machinable ceramic printed circuit boards (PCB), are designed, fabricated, installed, and tested in the Joint Texas Experimental Tokamak (J-TEXT) vacuum vessel for detecting the plasma radial and vertical displacements relative to the geometric center of the vacuum vessel in Ohmic discharges. Each coordinate is determined by a pair of variable cross-section Rogowski and saddle coils, which measure the tangential and normal magnetic fields (relative to the coil surface). These coils are suitable for mass production and offer advantages in vacuum compatibility and temperature tolerance that are important for J-TEXT. Position measurements using PCB coils are compared with those from soft x-ray image system and match the position well.

Qiu, S. S.; Zhuang, G.; Zhang, M.; Xia, D. H.; Rao, B.; Zhang, X. Q.; Pan, Y. [College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Gentle, K. [Institute of Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2010-10-15

307

Determination of a Magnetic Complex Antenna Factor of Double-Output Shielded Loop Antenna Using an Equivalent Circuit  

NASA Astrophysics Data System (ADS)

A method and a simple equation for determining the magnetic complex antenna factor (M-CAF) of a shielded loop antenna are presented. The investigated shielded loop antenna has two output ports of which outputs are differentially combined in time domain. The low-directivity of this loop antenna is useful for mapping magnetic fields. The proposed method is based on an equivalent circuit of the antenna system. The derived equation makes it possible to determine the M-CAF from the calculated effective length of the loop element and the measured reflection coefficient at an output port. The proposed method is confirmed by comparison between the waveform reconstruction using the M-CAF and the theoretical calculation for an electromagnetic pulse radiated from a monopole antenna on a ground plane.

Kohmura, Akiko; Iwasaki, Takashi

308

New printed circuit boards magnetic coils in the vacuum vessel of J-TEXT tokamak for position measurement.  

PubMed

Four sets of magnetic diagnostic coils, which are printed on machinable ceramic printed circuit boards (PCB), are designed, fabricated, installed, and tested in the Joint Texas Experimental Tokamak (J-TEXT) vacuum vessel for detecting the plasma radial and vertical displacements relative to the geometric center of the vacuum vessel in Ohmic discharges. Each coordinate is determined by a pair of variable cross-section Rogowski and saddle coils, which measure the tangential and normal magnetic fields (relative to the coil surface). These coils are suitable for mass production and offer advantages in vacuum compatibility and temperature tolerance that are important for J-TEXT. Position measurements using PCB coils are compared with those from soft x-ray image system and match the position well. PMID:21033989

Qiu, S S; Zhuang, G; Zhang, M; Xia, D H; Rao, B; Zhang, X Q; Pan, Y; Gentle, K

2010-10-01

309

An Analytic Circuit-Based Model for White and Flicker Phase Noise in LC Oscillators  

Microsoft Academic Search

A general circuit-based model of LC oscillator phase noise applicable to both white noise and 1\\/f noise is presented. Using the Kurokawa theory, differential equations governing the relationship between amplitude and phase noise at the tank are derived and solved. Closed form equations are obtained for the IEEE oscillator phase noise for both white and 1\\/f noise. These solutions introduce

Jayanta Mukherjee; Patrick Roblin; Siraj Akhtar

2007-01-01

310

A general model for differential power analysis attacks to static logic circuits  

Microsoft Academic Search

In this paper, a general model of multi-bit differential power analysis (DPA) attacks to static logic circuits is proposed, with emphasis on symmetric-key cryptographic algorithms. The main parameters that are of interest in practical DPA attacks are analytically derived by introducing suitable approximations. Several interesting properties of DPA attacks are derived, allowing a deep understanding of the vulnerability of algorithms

Massimo Alioto; Massimo Poli; Santina Rocchi

2008-01-01

311

Modeling of power supply noise in large chips with nonlinear circuits  

Microsoft Academic Search

In this paper, a method for including the CMOS inverter characteristics into the FDTD simulation has been presented. This model was verified by comparing it with SPICE, followed by a large network simulation with both linear and nonlinear circuits. As an example of the application of this method, an H-tree clock network was simulated to compute the power supply noise

Jinseong Choi; Madhavan Swaminathan; Raj Master

2002-01-01

312

Modelling of arc duration and erosion in electrical contacts of circuit breakers  

Microsoft Academic Search

The dynamics of the electrical and temperature fields in opening electrical contacts of circuit breakers is described by a non-linear transient mathematical model. It takes into account the interaction of the electrical arc with the contact surface, heat transfer with the melting and evaporation of the contact material, and the non-linear dependence of the arc electrical and thermal conductivity. The

H. Nouri; S. N. Kharin; S. I. Tirmizi; S.-U. Islam

2004-01-01

313

SSSC circuit model for three-wire systems coupled with Delta-connected transformer  

Microsoft Academic Search

This paper presents a new circuit model of SSSC based on state equations in three-wired systems. SSSC is a series compensator of FACTS family. It injects an almost sinusoidal voltage with variable amplitude and is equivalent to an inductive or a capacitive reactance in series with the transmission line. The analysis of a power electronics system is complex, owing to

G. Abdollahi Sarvi; M. T. Bina

2010-01-01

314

Distributed equivalent-circuit model for traveling-wave FET design  

Microsoft Academic Search

Based on reliable theoretical results, a distributed MESFET model is developed. It consists of equivalent-circuit elements which can be evaluated directly from FET material constants and geometry. The deviations with respect to full-wave-analysis results are investigated and some applications are shown.

Wolfgang Heinrich

1987-01-01

315

New models and heuristics for component placement in printed circuit board assembly  

Microsoft Academic Search

The paper considers an optimization problem arising in the automated manufacture of printed circuit boards. An essential part of this problem is to determine good component pick and place sequences as this can reduce the overall assembly time significantly. This component placement sequence problem can be modelled as a Travelling Salesman Problem, however complex machine and process specifications also arise

Edmund K. Burke; Peter I. Cowling; Ralf Keuthen

1999-01-01

316

Integration of environmental factors in process modeling for printed circuit board manufacturing. I. Assembly  

Microsoft Academic Search

This paper develops a planning methodology for integrating manufacturing related environmental factors into the design and control of production systems, with applications to printed circuit board assembly. Central to this methodology is the definition of manufacturing models for unit-level and batch processes that relate process parameters and component design features to waste streams, energy consumption, yield and process time. Process

P. Worhach; P. Sheng

1997-01-01

317

Modeling MOS snapback and parasitic bipolar action for circuit-level ESD and high current simulations  

Microsoft Academic Search

A circuit-level simulator for ESD and EOS is presented. Equations for modeling the high current behavior of NMOS and PMOS transistors have been developed and implemented in SPICE. A simple and practical extraction methodology for obtaining the bipolar parameters is given, which uses the three terminal currents obtained from a single high current I-V curve. Simulation results are presented and

Ajith Amerasekera; Srini Ramaswamy; Mi-Chang Chang; Charvaka Duvvury

1996-01-01

318

Surface-Charge-Based Micro-Models--A Solid Foundation for Learning about Direct Current Circuits  

ERIC Educational Resources Information Center

|This study explores how the use of a surface-charge-based instructional approach affects introductory university level students' understanding of direct current (dc) circuits. The introduced teaching intervention includes electrostatics, surface-charge-based micro-models that explain the existence of an electric field inside the current-carrying…

Hirvonen, P. E.

2007-01-01

319

An efficient nonquasi-static diode model for circuit simulation  

Microsoft Academic Search

Based on the partitioned-charge-based modeling approach, a general nonquasi-static dynamic charge element is derived to simulate both transient behavior and high-frequency characteristics of a semiconductor diode. A new model parameter ? is introduced to describe the dynamic charge redistribution time for a diode. By partitioning the total base charge into quasi-static (QS) and nonquasi-static (NQS) terms, a single-? (level 2)

Andrew T. Yang; Yu Liu; Jack T. Yao

1994-01-01

320

Anisotropy in three-phase transformer circuit model  

Microsoft Academic Search

In this paper, an important discussion of transformer design and modeling is given. Anisotropy effects of the transformer laminations have been stressed in the light of the investigation of a three-phase three-limb transformer T-joint. Three simple T-joint modeling schemes accounting for the lamination anisotropy are proposed. The fundamental result is that the flux lines remain almost parallel to the rolling

Mohammed Elleuch; Michel Poloujadoff

1997-01-01

321

An environmental assessment model applied to printed circuit board manufacturing  

Microsoft Academic Search

Environmental consciousness in manufacturing is becoming increasingly important, due to market pressure and government regulations.\\u000a As a result, there is an immediate need to develop a model which can effectively assess the impacts of pollution in manufacturing.\\u000a In this paper, an environmental assessment model is developed based on the combining of the “interval method” with the network\\u000a analytic method and

I. K. Hui

2007-01-01

322

A Charge-Based OTFT Model for Circuit Simulation  

Microsoft Academic Search

In this paper, a mathematical model for the dc\\/dynamic current of organic thin-film transistors is proposed. The model is based on the variable-range hopping transport theory, i.e., thermally activated tunneling of carriers between localized states, and the mathematical expression of the current is formulated by means of the channel accumulation charge. It accurately accounts for below-threshold, linear, and saturation operating

Fabrizio Torricelli; Zsolt M. Kovacs-Vajna; Luigi Colalongo

2009-01-01

323

NeuroGPS: automated localization of neurons for brain circuits using L1 minimization model  

NASA Astrophysics Data System (ADS)

Drawing the map of neuronal circuits at microscopic resolution is important to explain how brain works. Recent progresses in fluorescence labeling and imaging techniques have enabled measuring the whole brain of a rodent like a mouse at submicron-resolution. Considering the huge volume of such datasets, automatic tracing and reconstruct the neuronal connections from the image stacks is essential to form the large scale circuits. However, the first step among which, automated location the soma across different brain areas remains a challenge. Here, we addressed this problem by introducing L1 minimization model. We developed a fully automated system, NeuronGlobalPositionSystem (NeuroGPS) that is robust to the broad diversity of shape, size and density of the neurons in a mouse brain. This method allows locating the neurons across different brain areas without human intervention. We believe this method would facilitate the analysis of the neuronal circuits for brain function and disease studies.

Quan, Tingwei; Zheng, Ting; Yang, Zhongqing; Ding, Wenxiang; Li, Shiwei; Li, Jing; Zhou, Hang; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

2013-04-01

324

NeuroGPS: automated localization of neurons for brain circuits using L1 minimization model  

PubMed Central

Drawing the map of neuronal circuits at microscopic resolution is important to explain how brain works. Recent progresses in fluorescence labeling and imaging techniques have enabled measuring the whole brain of a rodent like a mouse at submicron-resolution. Considering the huge volume of such datasets, automatic tracing and reconstruct the neuronal connections from the image stacks is essential to form the large scale circuits. However, the first step among which, automated location the soma across different brain areas remains a challenge. Here, we addressed this problem by introducing L1 minimization model. We developed a fully automated system, NeuronGlobalPositionSystem (NeuroGPS) that is robust to the broad diversity of shape, size and density of the neurons in a mouse brain. This method allows locating the neurons across different brain areas without human intervention. We believe this method would facilitate the analysis of the neuronal circuits for brain function and disease studies.

Quan, Tingwei; Zheng, Ting; Yang, Zhongqing; Ding, Wenxiang; Li, Shiwei; Li, Jing; Zhou, Hang; Luo, Qingming; Gong, Hui; Zeng, Shaoqun

2013-01-01

325

Six-input lookup table circuit with 62% fewer transistors using nonvolatile logic-in-memory architecture with series/parallel-connected magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

A compact 6-input lookup table (LUT) circuit using nonvolatile logic-in-memory (LIM) architecture with series/parallel-connected magnetic tunnel junction (MTJ) devices is proposed for a standby-power-free field-programmable gate array. Series/parallel connections of MTJ devices make it possible not only to reduce the effect of resistance variation, but also to enhance the programmability of resistance values, which achieves a sufficient sensing margin even when process variation is serious in the recent nanometer-scaled VLSI. Moreover, the additional MTJ devices do not increase the effective chip area because the configuration circuit using MTJ devices is simplified and these devices are stacked over the CMOS plane. As a result, the transistor counts of the proposed circuit are reduced by 62% in comparison with those of a conventional nonvolatile LUT circuit where CMOS-only-based volatile static random access memory cell circuits are replaced by MTJ-based nonvolatile ones.

Suzuki, D.; Natsui, M.; Endoh, T.; Ohno, H.; Hanyu, T.

2012-04-01

326

An Equivalent Circuit Model for Vertical Comb Drive MEMS Optical Scanner Controlled by Pulse Width Modulation  

NASA Astrophysics Data System (ADS)

An equivalent circuit model for the resonant-type vertical comb-driven optical MEMS (micro electro mechanical system) scanner has been developed based on the simple extension of the parallel-plate model. Both the electrostatic torque and the induction charge models are interpreted by using the equation-defined nonlinear dependent current source on the electrical circuit simulator platform. A systematic procedure has been investigated to fit the analytical model with the experimental results by using fitting parameters including the damping coefficient, the suspension width, and the comb gap. The developed simulation model has been used to verify a new control scheme to tune the scanner's oscillation amplitude in resonance by means of the pulse-width modulation of voltage at a given pulse height; the result indicates the effective use of digital electronics for the comb-driven optical scanner.

Maruyama, Satoshi; Nakada, Muneki; Mita, Makoto; Takahashi, Takuya; Fujita, Hiroyuki; Toshiyoshi, Hiroshi

327

Computer modeling in gravity and magnetic interpretation  

Microsoft Academic Search

Computation of anomalous gravity and magnetic fields generated by various models is a necessary step if techniques of curve-matching are to be used for quantitative interpretation of potential field data. Recently developed methods show that anomalous magnetic and gravity fields are completely determined by the divergence of magnetization and the first vertical derivative of density, respectively. By use of these

B. K. Bhattacharyya

1978-01-01

328

Olfactory functions scale with circuit restoration in a rapidly reversible Alzheimer's disease model.  

PubMed

Neural circuits maintain a precise organization that is vital for normal brain functions and behaviors, but become disrupted during neurological disease. Understanding the connection between wiring accuracy and function to measure disease progression or recovery has been difficult because of the complexity of behavioral circuits. The olfactory system maintains well-defined neural connections that regenerate throughout life. We previously established a reversible in vivo model of Alzheimer's disease by overexpressing a humanized mutated amyloid precursor protein (hAPP) in olfactory sensory neurons (OSNs). Using this model, we currently show that hAPP is present in the OSN axons of mutant mice, which exhibit strong caspase3 signal and reduced synaptic protein expression by 3 weeks of age. In the olfactory bulb, we show that glomerular structure is distorted and OSN axonal convergence is lost. In vivo functional imaging experiments further demonstrate disruption of the glomerular circuitry, and behavioral assays reveal that olfactory function is significantly impaired. Because OSNs regenerate, we also tested if the system could recover from hAPP-induced disruption. We found that after 1 or 3 weeks of shutting-off hAPP expression, the glomerular circuit was partially restored both anatomically and functionally, with behavioral deficits similarly reversed. Interestingly, the degree of functional recovery tracked directly with circuit restoration. Together, these data demonstrate that hAPP-induced circuit disruption and subsequent recovery can occur rapidly and that behavior can provide a measure of circuit organization. Thus, olfaction may serve as a useful biomarker to both follow disease progression and gauge potential recovery. PMID:23884929

Cheng, Ning; Bai, Li; Steuer, Elizabeth; Belluscio, Leonardo

2013-07-24

329

Characterization and modeling of RF substrate coupling effects due to vertical interconnects in 3D integrated circuit stacking  

Microsoft Academic Search

This paper discusses substrate coupling effects in 3D integrated circuits carried by TSV interconnects (Through Silicon Vias). These electrical couplings lead to several impacts on 3D circuit performance. RF (Radio Frequency) characterizations have been performed on dedicated test structures in order to extract electrical models of substrate coupling and make obvious this phenomenon. New modeling tools for predictive studies have

E. Eid; T. Lacrevaz; C. Bermond; S. de Rivaz; S. Capraro; J. Roullard; L. Cadix; B. Fle?chet; A. Farcy; P. Ancey; F. Calmon; O. Valorge; P. Leduc

2010-01-01

330

Biophysical Models of Neural Computation: Max and Tuning Circuits.  

National Technical Information Service (NTIS)

Pooling under a softmax operation and Gaussian-like tuning in the form of a normalized dotproduct were proposed as the key operations in a recent model of object recognition in the ventral stream of visual cortex. We investigate how these two operations m...

U. Knoblich J. Bouvrie T. Poggio

2007-01-01

331

MODELING PRINTED CIRCUIT BOARDS WITH EMBEDDED DECOUPLING CAPACITANCE  

Microsoft Academic Search

Embedded capacitance is an alternative to discrete decoupling capacitors and is achieved by enhancing the natural capacitance between power and ground planes. New materials have recently been developed by competing companies that promise to reduce the cost and improve the performance of boards with embedded capacitance. This paper introduces simple models for embedded capacitance boards and examines the properties of

Minjia Xu; T. Hubing; J. Drewniak; T. Van Doren; R. DuBroff

332

Energetic model of ferromagnetic hysteresis: Isotropic magnetization  

NASA Astrophysics Data System (ADS)

The model is based on considerations of energy balance and statistical domain behavior. The parameters are related to macroscopic hysteresis features such as coercivity, initial susceptibility, saturation, and remanence and identification strategies are presented for static and dynamic magnetization processes. Furthermore, the model parameters are related to spontaneous magnetization, magnetocrystalline anisotropy, magnetostriction, and microstructure geometry which assist in the interpretation of the hysteresis dependence on stress, temperature, and direction of magnetization. Examples and predictions are the magnetization reversal in low dimensional structures, stress demagnetization, temporary decay of magnetization, Barkhausen noise, and the behavior of materials with multiple phases. Finally, the fictitious statistical domains (or unit magnetization reversals) are related to the magnetic spin moments, which enables a quantum-mechanical interpretation of the model.

Hauser, Hans

2004-09-01

333

Modeling of Magnetically Levitated Planar Actuators With Moving Magnets  

Microsoft Academic Search

This paper presents three types of magnetostatic models of ironless planar actuators with moving magnets. The models predict the force and torque exerted on the translator of the actuator, which can be positioned in six degrees-of-freedom with respect to the stator coils. The force and torque are calculated with the Lorentz force law. The analytical and numerical models can be

J. W. Jansen; C. M. M. van Lierop; E. A. Lomonova; A. J. A. Vandenput

2007-01-01

334

Analytical model for permanent magnet motors with surface mounted magnets  

Microsoft Academic Search

This paper presents an analytical method of modeling permanent magnet (PM) motors. The model is dependent only on geometrical and materials data which makes it suitable for insertion into design programs, avoiding long finite element analysis (FEA) calculations. The modeling procedure is based on the calculation of the air gap field density waveform at every time instant. The waveform is

A. B. Proca; A. Keyhani; A. El-Antably; Wenzhe Lu; Min Dai

2003-01-01

335

Systems-level modeling of neuronal circuits for leech swimming  

Microsoft Academic Search

This paper describes a mathematical model of the neuronal central pattern generator (CPG) that controls the rhythmic body\\u000a motion of the swimming leech. The systems approach is employed to capture the neuronal dynamics essential for generating coordinated oscillations of cell membrane potentials\\u000a by a simple CPG architecture with a minimal number of parameters. Based on input\\/output data from physiological experiments,

M. Zheng; W. Ottor Friesen; T. Iwasaki

2007-01-01

336

Computer circuit analysis of induced currents in the MFTF-B magnet system  

SciTech Connect

An analysis was made of the induced current behavior of the MFTF-B magnet system. Although the magnet system consists of 22 coils, because of its symmetry we considered only 11 coils in the analysis. Various combinations of the coils were dumped either singly or in groups, with the current behavior in all magnets calculated as a function of time after initiation of the dump.

Magnuson, G.D.; Woods, E.L.

1981-10-23

337

Canonical modeling of power processing circuits based on the POPI concept  

Microsoft Academic Search

The fundamental power-processing properties of switching converter circuits are modeled using generalized power-conservative (POPI) networks. Depending on the application, it may be most appropriate to model the first-order converter properties as those of an ideal transformer, gyrator, loss-free resistor, or other POPI network. These basic functions can be obtained either through selection of a topology that naturally possesses the desired

S. Singer; R. W. Erickson

1992-01-01

338

Modeling and simulation of high-frequency integrated circuits based on scattering parameters  

Microsoft Academic Search

We ~esent an approach for accurate modeling and simulation of high-frequency circuits. This capability results from 1) efficient determina tion of scattering matrices of microstrip interconnects using Prony’s method and nonlinear optimization for the evaluation of Som,erfeld integrals, 2) extraction of a generalized charge-based FET model from scattering parameter data and 3) an improved harmonic ba@we technique based on the

Andrew T. Yang; C. H. Chart; Jack T. Yao; R. R. Daniels; J. P. Harrang

1991-01-01

339

A simple and effective model for electromagnetic bandgap structures embedded in printed circuit boards  

Microsoft Academic Search

Using a transmission-line model and considering a simple lumped-element substitute for the patch-via structure, a first-order, but detailed, quantitative and qualitative analysis of the filtering properties of a metallo-dielectric electromagnetic bandgap structure embedded in a printed circuit board is presented. This model is able to describe the resonant properties of the structure as well as its pass-band and stop-band regions.

Shahrooz Shahparnia; Omar M. Ramahi

2005-01-01

340

Behavioral Modeling and Simulation of Semiconductor Devices and Circuits Using VHDL-AMS  

Microsoft Academic Search

During the past few years, a lot of work has been done on behavioral models and simulation tools. But a need of modeling strategy still remains. The VHDL-AMS language supports the description of analog electronic circuits using ordinary differential algebraic equations (ODAEs), in addition to its support for describing discrete-event systems. For VHDL-AMS to be useful to the analog design

R. Mortezaee; G. R. Karimi; S. Mirzakuchaki

2007-01-01

341

Frequency-independent equivalent-circuit model for on-chip spiral inductors  

Microsoft Academic Search

A wide-band, physical and scalable 2-? equivalent circuit model for on-chip spiral inductors is developed. Using fre- quency-independent RLC elements, it accurately captures R(f) and L(f) characteristics beyond the self-resonant fre- quency. This new model is fully compatible with both AC and transient analysis. Verification with measurement data demonstrates excellent scalability for a wide range of induc- tor configurations.

Yu Cao; Robert A. Groves; D. Zamdmer; Jean-Olivier Plouchart; Richard A. Wachnik; Xuejue Huang; Chenming Hu

2003-01-01

342

An improved DC model for circuit analysis programs for submicron GaAs MESFET's  

Microsoft Academic Search

An improved submicron GaAs MESFET model is presented which is suitable for nonlinear small-signal circuit designs. The Kacprzak-Materka model, which simulates the dc characteristics of large signal devices has been modified to predict the behavior of submicron devices. In this modification the concept of a shift in threshold voltage has been introduced. It has been shown that without taking into

Mansoor M. Ahmed; Haroon Ahmed; Peter H. Ladbrooke

1997-01-01

343

EM-ANN models for microstrip vias and interconnects in dataset circuits  

Microsoft Academic Search

A novel approach for accurate and efficient modeling of monolithic microwave\\/millimeter wave integrated circuit (MMIC) components by using electromagnetically trained artificial neural network (EM-ANN) software modules is presented. Full-wave EM analysis is employed to characterize MMIC components. Structures for simulation are chosen using design of experiments (DOE) methodology. EM-ANN models are then trained using physical parameters as inputs and S-parameters

Paul M. Watson; Kuldip C. Gupta

1996-01-01

344

Effects of the Built-in Permanent Magnet Rotor on the Equivalent Circuit Parameters of a Permanent Magnet Induction Generator  

Microsoft Academic Search

The permanent magnet induction generator (PMIG) is a new type of induction generator (IG) that has a permanent magnet (PM) rotor inside a squirrel cage rotor. The squirrel cage rotor is linked to the shaft, and the built-in PM rotor is free to rotate against the shaft. One of the notable features of the PMIG is that the power density

Toshihiro Tsuda; Tadashi Fukami; Yasunori Kanamaru; Toshio Miyamoto

2007-01-01

345

Utilization of magnetic and electrostatic separation in the recycling of printed circuit boards scrap  

Microsoft Academic Search

The progress of the technology is directly related to the growth of production and consumption of electrical\\/electronics equipment, especially of personal computers. This type of equipment has a relatively short average lifetime, 2–3 years. The amount of defective or obsolete equipment has been increasing substantially; consequently its disposition and\\/or recycling should be studied.In this work, printed circuit boards, which are

H. M. Veit; T. R. Diehl; A. P. Salami; J. S. Rodrigues; A. M. Bernardes; J. A. S. Tenório

2005-01-01

346

A Circuit Analog Model for Studying Quantitative Water Relations of Plant Tissues 1  

PubMed Central

Using arrays of resistors and capacitors, a lumped circuit analog of plant tissue is developed. The circuit elements of the analog are identified in terms of physiological variables (hydraulic conductivities, water capacities, and cell dimensions) which can be measured in the laboratory. With the aid of a circuit simulation subroutine, the model was solved to predict water potential distributions as a function of position and time in plant tissues of three, six, and nine cells. Results presented for the six-cell case indicate that local equilibrium may or may not occur depending on the actual values of tissue hydraulic conductivities, water capacities, and the rate of change of water potential at the tissue boundaries. However, present measurements and estimates of tissue parameters suggest that local equilibrium is more the rule than the exception. Membrane resistance is an especially important parameter because it serves to isolate the vacuoles from the cell walls in addition to increasing the natural vacuole response time to changes in water potential. The proposed model should be useful in studying water transport processes in roots, stems, and leaves. Nonhomogeneity can be taken into account easily. Nonlinearity (changes in circuit parameter values with potential) which is known to occur in plant tissues could be incorporated also if the required information were available.

Molz, Fred J.; Kerns, David V.; Peterson, Curt M.; Dane, Jacob H.

1979-01-01

347

Local cortical circuit model inferred from power-law distributed neuronal avalanches.  

PubMed

How cortical neurons process information crucially depends on how their local circuits are organized. Spontaneous synchronous neuronal activity propagating through neocortical slices displays highly diverse, yet repeatable, activity patterns called "neuronal avalanches". They obey power-law distributions of the event sizes and lifetimes, presumably reflecting the structure of local circuits developed in slice cultures. However, the explicit network structure underlying the power-law statistics remains unclear. Here, we present a neuronal network model of pyramidal and inhibitory neurons that enables stable propagation of avalanche-like spiking activity. We demonstrate a neuronal wiring rule that governs the formation of mutually overlapping cell assemblies during the development of this network. The resultant network comprises a mixture of feedforward chains and recurrent circuits, in which neuronal avalanches are stable if the former structure is predominant. Interestingly, the recurrent synaptic connections formed by this wiring rule limit the number of cell assemblies embeddable in a neuron pool of given size. We investigate how the resultant power laws depend on the details of the cell-assembly formation as well as on the inhibitory feedback. Our model suggests that local cortical circuits may have a more complex topological design than has previously been thought. PMID:17226088

Teramae, Jun-Nosuke; Fukai, Tomoki

2007-01-17

348

OBSERVING AND MODELLING STELLAR MAGNETIC FIELDS. 2. MODELS  

Microsoft Academic Search

In this chapter, we examine the question of how spectropo- larimetric observations of magnetic stars may be modelled, and how modelling techniques may be used to extract much detailed informa- tion about the stellar magnetic field and other characteristics of the magnetized stellar atmosphere. In the preceding chapter, we discussed how the energy levels of atoms are split by a

John D. Landstreet

349

Magnetic field diffusion modeling of a small enclosed firing system  

SciTech Connect

Intense magnetic fields exist in the immediate vicinity of a lightning strike (and near power lines). Conducting barriers increase the rise time (and thus decrease the rise rate) interior to the barrier, but typically do not prevent penetration of the magnetic field, since the lightning current fall time may be larger than the barrier diffusion time. Thus, substantial energy is present in the interior field, although the degradation of rise rate makes it more difficult to couple into electrical circuits. This report assesses the threat posed by the diffusive magnetic field to interior components and wire loops (where voltages are induced). Analytical and numerical bounding analyses are carried out on a pill box shaped conducting barrier to develop estimates for the worst case magnetic field threats inside the system. Worst case induced voltages and energies are estimated and compared with threshold charge voltages and energies on the output capacitor of the system. Variability of these quantities with respect to design parameters are indicated. The interior magnetic field and induced voltage estimates given in this report can be used as excitations for more detailed interior and component models.

Warne, L.K.; Merewether, K.O.

1996-01-01

350

Circuit and microarchitecture evaluation of 3D stacking magnetic RAM (MRAM) as a universal memory replacement  

Microsoft Academic Search

Magnetic Random Access Memory (MRAM) has been considered as a promising memory technology due to many attractive proper- ties. Integrating MRAM with CMOS logic may incur extra manu- facture cost, due to its hybrid magnetic-CMOS fabrication process. Stacking MRAM on top of CMOS logics using 3D integration is a way to minimize this cost overhead. In this paper, we discuss

Xiangyu Dong; Xiaoxia Wu; Guangyu Sun; Yuan Xie; Helen Li; Yiran Chen

2008-01-01

351

Magnetic network model including loss separation and Preisach principles for the evaluation of core losses in devices  

NASA Astrophysics Data System (ADS)

In this paper, a method is developed to calculate the core loss in a switched reluctance machine. The magnetic circuit of the motor is described as a magnetic network. The electromagnetic behavior of each magnetic network element takes into account the iron loss using the Preisach model and the principle of loss separation. Using the numerical routines, the local core loss in the different motor sections is calculated. The global core loss is compared with the experimentally determined core loss.

Dupré, Luc; Sergeant, Peter; Vandenbossche, Lode

2005-05-01

352

Mathematical modelling of magnetically targeted drug delivery  

Microsoft Academic Search

A mathematical model for targeted drug delivery using magnetic particles is developed. This includes a diffusive flux of particles arising from interactions between erythrocytes in the microcirculation. The model is used to track particles in a vessel network. Magnetic field design is discussed and we show that it is impossible to specifically target internal regions using an externally applied field.

Andrew D. Grief; Giles Richardson

2005-01-01

353

Inter-neuronal correlation distinguishes mechanisms of direction selectivity in cortical circuit models.  

PubMed

Direction selectivity is a fundamental physiological property that arises from primary visual cortex (V1) circuitry, yet basic questions of how direction-selective (DS) receptive fields are constructed remain unanswered. We built a set of simple, plausible neuronal circuits that produce DS cells via different mechanisms and tested these circuits to determine how they can be distinguished experimentally. Our models consisted of populations of spiking units representing physiological cell classes ranging from LGN cells to V1 complex DS cells. They differed in network architecture and DS mechanism, including linear summation of non-DS simple-cell inputs or nonlinear pairwise combinations of non-DS inputs. The circuits also varied in the location of the DS time delay and whether the DS interaction was facilitatory or suppressive. We tested the models with visual stimuli often used experimentally, including sinusoidal gratings and flashed bars, and computed shuffle-corrected cross-correlograms (CCGs) of spike trains from pairs of units that would be accessible to extracellular recording. We found that CCGs revealed fundamental features of the DS models, including the location of signal delays in the DS circuit and the sign (facilitatory or suppressive) of DS interactions. We also found that correlation was strongly stimulus-dependent, changing with direction and temporal frequency in a manner that generalized across model architectures. Our models make specific predictions for designing, optimizing, and interpreting electrophysiology experiments aimed at resolving DS circuitry and provide new insights into mechanisms that could underlie stimulus-dependent correlation. The models are available and easy to explore at www.imodel.org. PMID:22745482

Baker, Pamela M; Bair, Wyeth

2012-06-27

354

Prediction Model for Production Indexes of a Flotation Circuit Based on Adaptive PCA and Composite Kernel Support Vector Regression  

Microsoft Academic Search

This An accurate prediction of important production indexes such as recovery rate and concentrate grade is essential for successful monitoring and controlling of a flotation circuit. However, due to the inherent characteristics of a flotation circuit such as time-delay, strong nonlinearities and uncertainties, these production indices are usually difficult to predict accurately. In this paper, a prediction model was developed

Huizhi Yang; Shaoyong Zhao

2010-01-01

355

Tuition and Memory: Mental Models and Cognitive Processing in Japanese Children's Work on D.C. Electrical Circuits.  

ERIC Educational Resources Information Center

|Focuses on the familiar problem of students' understanding of elementary electrical circuits from a much neglected point of view. Suggests that the patterning commonly found in students' ideas might have its roots in the cognitive processing with which students operate their mental models of d.c. electrical circuits. Studies Japanese 10-11 year…

Asami, Noriaki; King, Julien; Monk, Martin

2000-01-01

356

A model of grinding-classification circuit including particles size distribution and liberation of material: Application to the design and retrofit of flotation circuit  

Microsoft Academic Search

In this study models were developed based on population balances which included the effects of redistribution of material of different composition classes and particle sizes with four configuration alternatives of grinding and classification circuits (grinding, grinding-classification, classification-grinding, classification-grinding-classification). The models for all these configurations were linear in character, and applicable in design or retrofit strategies in which there is an

David A. Méndez; Edelmira D. Gálvez; Luis A. Cisternas

2007-01-01

357

Limb movements during locomotion: Tests of a model of an intersegmental coordinating circuit.  

PubMed

During normal forward swimming, the swimmerets on neighboring segments of the crayfish abdomen make periodic power-stroke movements that have a characteristic intersegmental difference in phase. Three types of intersegmental interneurons that originate in each abdominal ganglion are necessary and sufficient to maintain this phase relationship. A cellular model of the intersegmental coordinating circuit that also produces the same intersegmental phase has been proposed. In this model, coordinating axons synapse with local interneurons in their target ganglion and form a concatenated circuit that links neighboring segmental ganglia. This model assumed that coordinating axons projected to their nearest-neighboring ganglion but not farther. We tested this assumption in two sets of experiments. If the assumption is correct, then blocking synaptic transmission in an intermediate ganglion should uncouple swimmeret activity on opposite sides of the block. We bathed individual ganglia in a low Ca(2+)-high Mg(2+) saline that effectively silenced both motor output from the ganglion and the coordinating interneurons that originated in it. With this block in place, other ganglia on opposite sides of the block could nonetheless maintain their normal phase difference. Simultaneous recordings of spikes in coordinating axons on opposite sides of the blocked ganglion showed that these axons projected beyond the neighboring ganglion. Selective bilateral ablation of the tracts in which these axons ran showed that they were necessary and usually sufficient to maintain coordination across a blocked ganglion. We discuss revisions of the cellular model of the coordinating circuit that would incorporate these new results. PMID:11567077

Tschuluun, N; Hall, W M; Mulloney, B

2001-10-01

358

Pulsed magnetic field measurement using a ferrite waveguide in a phase bridge circuit  

SciTech Connect

There are several standard methods used for measuring pulsed magnetic fields. However the induction or Hall probe methods have limited bandwidth and experience reflection problems. The integrated magnetic field can only be found by measuring along the entire length of the magnet. Problems with reflections, noise and bandwidth will limit the accuracy of measurement. Presented in the following paper is a method for measuring pulsed fields without the typical noise errors and bandwidth limitations. This paper will describe a phase bridge network that relies upon the permeability of a ferrite waveguide to accurately measure the integrated field of a Main Injector kicker magnet. The authors present some data taken with the system, a first pass at the analysis of this data, and discuss some possible design variations.

William A Pellico and Patrick Colestock

2002-07-01

359

Magnetorheological fluids: characterization and modeling of magnetization  

NASA Astrophysics Data System (ADS)

This paper presents a magnetization model that endeavors to capture the change in the rheological behavior due to the application of magnetic fields to ferrofluids (FFs) and magnetorheological fluids (MRFs). Samples of Ferrotec APG 2115 FF and Lord MRF-122-2ED MRF have been tested using an Anton Paar MCR 501 rotational rheometer fitted with a parallel-plate measuring system. On the basis of the results, the FF has been modeled using the Newtonian model whereas the MRF has been adjusted using the Bingham and Herschel-Bulkley models. All three models have been extended using the herein-proposed magnetization model, that provides good adjustment of any of the models to the entire range of applied magnetic field.

Zubieta, M.; Eceolaza, S.; Elejabarrieta, M. J.; Bou-Ali, M. M.

2009-09-01

360

The magnetic circuit of an axial field D.C. electrical machine  

Microsoft Academic Search

A permanent magnet d.c. machine is described, with an axial field and a disc-shaped armature. The potential distribution is calculated in three-dimensions for high-coercivity magnets, for which a uniform intrinsic magnetisation can be assumed. This shows the importance of not assuming a constant potential over the pole surface, and of not reducing the system to two-dimensions. The field in the

P. Campbell

1975-01-01

361

Improved equivalent circuit and analytical model for amorphous silicon solar cells and modules  

SciTech Connect

An improved equivalent circuit for hydrogenated amorphous silicon (a-Si:H) solar cells and modules is presented. It is based on the classic combination of a diode with an exponential current-voltage characteristic, of a photocurrent source plus a new term representing additional recombination losses in the i-layer of the device. This model/equivalent circuit matches the I(V) curves of a-Si:H cells over an illumination range of six order of magnitude. The model clearly separates effects related to the technology of the device (series and parallel resistance) and effects related to the physics of the pin-junction (recombination losses). It also allows an effective {mu}{tau} product in the i-layer of the device to be determined, characterizing its state of degradation.

Merten, J.; Asensi, J.M.; Voz, C.; Andreu, J. [Univ. de Barcelona (Spain). Dept. de Fisica Aplicada i Eletronica; Shah, A.V.; Platz, R. [Inst. de Microtechnique, Rue Breguet (Switzerland)

1998-02-01

362

Comprehensive Compact Models for the Circuit Simulation of Multichip Power Modules  

Microsoft Academic Search

This paper proposes the model development of a packaged semiconductor power module, for use in a circuit simulation environment. Focusing on railway traction applications, it considers a state-of-the-art 6.5 kV insulated gate bipolar transistor (IGBT) module, taking into account the antiparallel connection of IGBTs and free-wheeling diodes, and including all main electrothermal and electromagnetic effects associated with the multichip structure.

Alberto Castellazzi

2010-01-01

363

A system-level circuit model for multi- and single-chip CPUs  

Microsoft Academic Search

This report will detail a system level circuit model that has been used to predict the performance of microprocessors, gate arrays, and mainframe computers implemented in several IC technologies. Comparisons have been made on the basis of clock frequency, power dissipation and chip\\/module sizes. Predictions indicate that in ten years a 0.7?m CMOS micro-processor with 6-million transistors will execute 30-60

H. B. BakoglufX; J. D. Meindl

1987-01-01

364

Direct Determination of Multimode Equivalent Circuit Models for Discontinuities in Substrate Integrated Waveguide Technology  

Microsoft Academic Search

This paper presents a novel approach for the direct determination of equivalent circuit models of substrate integrated waveguide (SIW) components. This approach is based on the full-wave analysis of the SIW component by using the boundary integral-resonant mode expansion (BI-RME) method, which provides the admittance matrix of the component in the form of a pole expansion in the frequency domain.

M. Bozzi; L. Perregrini; Ke Wu

2006-01-01

365

A schematic-based design model for microphone and circuit integration  

Microsoft Academic Search

The transistor-level elements for condenser microphone design have been implemented in an IC design environment. Arbitrary diaphragm shapes can be composed and simulated by using our basic elements. The sensitivity and frequency response are obtained by co-simulation with the microphone and the readout circuit using Cadence\\/Spectrereg simulator. The new model is capable of dealing with the multi-field coupling effects including

Jen-Yi Chen; Shu-Sheng Lee; Peter Chang; Chun-Hsun Chu; Tamal Mukherjee; G. K. Fedder

2007-01-01

366

Equivalent circuit characterization of a periodically loaded ferrite phase shifter  

Microsoft Academic Search

An equivalent circuit model is derived for a periodically loaded, non-reciprocal, ferrite phase shifter. It is shown that the enhanced differential phase shift that results from periodic loading can be explained by a change in the periodic circuit inductance and capacitance values that occur due to the propagation constant variation resulting from the ferrite toroid magnetization. By curve fitting the

W. G. Spaulding; T. C. Pierce

1974-01-01

367

Computational investigation of the magnetic-field distribution in a 145kV\\/40kA rotary-arc circuit breaker  

Microsoft Academic Search

Rotary-arc circuit breakers (CBs) rely on an externally imposed magnetic field to move the arc column in the arcing chamber, hence reducing contact erosion and enhancing the interruption capability. The three-dimensional computation of the magnetic field was carried out for a prototype 145-kV\\/40-kA rotary-arc CB and the influencing parameters were identified. It is shown that the presence of an arc

Qingmin Li; Joseph D. Yan

2006-01-01

368

High frequency electrical circuit model of chip-to-chip vertical via interconnection for 3-D chip stacking package  

Microsoft Academic Search

In this paper, we firstly propose the high frequency equivalent circuit model of the chip-to-chip vertical via based on its physical configuration. The model parameters are extracted from the measurement of S-parameters using a vector network analyzer up to 20GHz frequency range. The proposed circuit model is verified experimentally in frequency and time domains. Furthermore, the high frequency characteristics of

Chunghyun Ryu; Daehyun Chung; Junho Lee; Kwangyong Lee; Taesung Oh; Joungho Kim

2005-01-01

369

Modeling solar force-free magnetic fields  

Microsoft Academic Search

A class of nonlinear force-free magnetic fields is presented, described in terms of the solutions to a second-order, nonlinear ordinary differential equation. These magnetic fields are three-dimensional, filling the infinite half-space above a plane where the lines of force are anchored. They model the magnetic fields of the sun over active regions with a striking geometric realism. The total energy

B. C. Low; Y. Q. Lou

1990-01-01

370

A model study on the circuit mechanism underlying decision-making in Drosophila.  

PubMed

Previous elegant experiments in a flight simulator showed that conditioned Drosophila is able to make a clear-cut decision to avoid potential danger. When confronted with conflicting visual cues, the relative saliency of two competing cues is found to be a sensory ruler for flies to judge which cue should be used for decision-making. Further genetic manipulations and immunohistological analysis revealed that the dopamine system and mushroom bodies are indispensable for such a clear-cut or nonlinear decision. The neural circuit mechanism, however, is far from being clear. In this paper, we adopt a computational modeling approach to investigate how different brain areas and the dopamine system work together to drive a fly to make a decision. By developing a systems-level neural network, a two-pathway circuit is proposed. Besides a direct pathway from a feature binding area to the motor center, another connects two areas via the mushroom body, a target of dopamine release. A raised dopamine level is hypothesized to be induced by complex choice tasks and to enhance lateral inhibition and steepen the units' response gain in the mushroom body. Simulations show that training helps to assign values to formerly neutral features. For a circuit model with a blocked mushroom body, the direct pathway passes all alternatives to the motor center without changing original values, giving rise to a simple choice characterized by a linear choice curve. With respect to an intact circuit, enhanced lateral inhibition dependent on dopamine critically promotes competition between alternatives, turning the linear- into nonlinear choice behavior. Results account well for experimental data, supporting the reasonableness of model working hypotheses. Several testable predictions are made for future studies. PMID:21310589

Wu, Zhihua; Guo, Aike

2011-01-21

371

Reentrant excitation in an analog-digital hybrid circuit model of cardiac tissue  

NASA Astrophysics Data System (ADS)

We propose an analog-digital hybrid circuit model of one-dimensional cardiac tissue with hardware implementation that allows us to perform real-time simulations of spatially conducting cardiac action potentials. Each active nodal compartment of the tissue model is designed using analog circuits and a dsPIC microcontroller, by which the time-dependent and time-independent nonlinear current-voltage relationships of six types of ion channel currents employed in the Luo-Rudy phase I (LR-I) model for a single mammalian cardiac ventricular cell can be reproduced quantitatively. Here, we perform real-time simulations of reentrant excitation conduction in a ring-shaped tissue model that includes eighty nodal compartments. In particular, we show that the hybrid tissue model can exhibit real-time dynamics for initiation of reentries induced by uni-directional block, as well as those for phase resetting that leads to annihilation of the reentry in response to impulsive current stimulations at appropriate nodes and timings. The dynamics of the hybrid model are comparable to those of a spatially distributed tissue model with LR-I compartments. Thus, it is conceivable that the hybrid model might be a useful tool for large scale simulations of cardiac tissue dynamics, as an alternative to numerical simulations, leading toward further understanding of the reentrant mechanisms.

Mahmud, Farhanahani; Shiozawa, Naruhiro; Makikawa, Masaaki; Nomura, Taishin

2011-06-01

372

Evolution of the current wedge and the generator current circuit by fast reconnection  

Microsoft Academic Search

Temporal dynamics of the generator current circuit and the current wedge is studied on the basis of the spontaneous fast reconnection model. Once the fast reconnection jet causes magnetic field dipolarization, a magnetohydrodynamic (MHD) generator arises ahead of the magnetic loop top. The generator effect is so powerful that a current circuit is strongly driven in the generator region and

M. Ugai

2009-01-01

373

A joint field\\/circuit model of line-to-ring coupling structures and its application to the design of microstrip dual-mode filters and ring resonator circuits  

Microsoft Academic Search

A joint field\\/circuit model is proposed in this paper to characterize a class of line-to-ring coupling structures for design and optimization of microstrip dual-mode filters and ring resonator circuits. The generic model is derived from field theory and presented in terms of circuit elements by applying a newly developed numerical deembedding technique called “short-open calibration” in a deterministic method-of-moments scheme.

Lei Zhu; Ke Wu

1999-01-01

374

Magnetic field decay in model SSC dipoles  

Microsoft Academic Search

The authors have observed that some of our model SSC dipoles have long time constant decays of the magnetic field harmonics with amplitudes large enough to result in significant beam loss, if they are not corrected. The magnets were run at constant current at the SSC injection field level of 0.3 tesla for one to three hours and changes in

W. S. Gilbert; R. F. Althaus; P. J. Barale; R. W. Benjegerdes; M. A. Green; M. I. Green; R. M. Scanlan

1989-01-01

375

Geospace Environmental Modeling (GEM) magnetic reconnection challenge  

Microsoft Academic Search

The Geospace Environmental Modeling (GEM) Reconnection Challenge project is presented and the important results, which are presented in a series of companion papers, are summarized. Magnetic reconnection is studied in a simple Harris sheet configuration with a specified set of initial conditions, including a finite amplitude, magnetic island perturbation to trigger the dynamics. The evolution of the system is explored

J. Birn; J. F. Drake; M. A. Shay; B. N. Rogers; R. E. Denton; M. Hesse; M. Kuznetsova; Z. W. Ma; A. Bhattacharjee; A. Otto; P. L. Pritchett

2001-01-01

376

Effects of spike timing on winner-take-all competition in model cortical circuits.  

PubMed

Synaptic interactions in cortical circuits involve strong recurrent excitation between nearby neurons and lateral inhibition that is more widely spread. This architecture is commonly thought to promote a winner-take-all competition, in which a small fraction of neuronal responses is selected for further processing. Here I report that such a competition is remarkably sensitive to the timing of neuronal action potentials. This is shown using simulations of model neurons and synaptic connections representing a patch of cortical tissue. In the simulations, uncorrelated discharge among neuronal units results in patterns of response dominance and suppression, that is, in a winner-take-all competition. Synchronization of firing, however, prevents such competition. These results demonstrate a novel property of recurrent cortical-like circuits, suggesting that the temporal patterning of cortical activity may play an important part in selection among stimuli competing for the control of attention and motor action. PMID:10636938

Lumer, E D

2000-01-01

377

An efficient EMTP compatible algorithm for modelling switch-controlled drive circuits  

SciTech Connect

The possibility of opposite interactions between the machine systems and the switching circuits of converters has created a need for both better models and more efficient computer programs to conduct detailed simulation studies involving machines and arbitrary drive systems with switching circuits included. This paper will present an efficient and fully Electromagnetic Transients Program (EMTP) compatible numerical algorithm that introduces the resistive representations and the cut-set algorithm into the system formulation stages, such that the possible numerical problems as might be occurred from using the EMTP can be avoided and the system equations need to be solved can be minimized. Numerical verifications based on the proposed algorithm and the EMTP will be proved for illustrations.

Liu, C.T. (National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China). Dept. of Electrical Engineering)

1994-10-01

378

An equivalent circuit model and power calculations for the APS SPX crab cavities.  

SciTech Connect

An equivalent parallel resistor-inductor-capacitor (RLC) circuit with beam loading for a polarized TM110 dipole-mode cavity is developed and minimum radio-frequency (rf) generator requirements are calculated for the Advanced Photon Source (APS) short-pulse x-ray (SPX) superconducting rf (SRF) crab cavities. A beam-loaded circuit model for polarized TM110 mode crab cavities was derived. The single-cavity minimum steady-state required generator power has been determined for the APS SPX crab cavities for a storage ring current of 200mA DC current as a function of external Q for various vertical offsets including beam tilt and uncontrollable detuning. Calculations to aid machine protection considerations were given.

Berenc, T. (Accelerator Systems Division (APS))

2012-03-21

379

Circuit modeling and performance analysis of SWCNT bundle 3D interconnects  

NASA Astrophysics Data System (ADS)

Metallic carbon nanotubes (CNTs) have been proposed as a promising alternative to Cu interconnects in future integrated circuits (ICs) for their remarkable conductive, mechanical and thermal properties. Compact equivalent circuit models for single-walled carbon nanotube (SWCNT) bundles are described, and the performance of SWCNT bundle interconnects is evaluated and compared with traditional Cu interconnects at different interconnect levels for through-silicon-via-based three dimensional (3D) ICs. It is shown that at a local level, CNT interconnects exhibit lower signal delay and smaller optimal wire size. At intermediate and global levels, the delay improvement becomes more significant with technology scaling and increasing wire lengths. For 1 mm intermediate and 10 mm global level interconnects, the delay of SWCNT bundles is only 49.49% and 52.82% that of the Cu wires, respectively.

Libo, Qian; Zhangming, Zhu; Ruixue, Ding; Yintang, Yang

2013-09-01

380

Intracortical inhibitory circuits and sensory input: a study with transcranial magnetic stimulation in humans  

Microsoft Academic Search

We compared intracortical inhibition (ICI) following paired transcranial magnetic stimulation (TMS) (interstimulus interval, ISI: 3 ms) and the inhibition of motor evoked potentials (MEPs) to TMS induced by stimulation of the median nerve (ISI: 200 ms) in six normal subjects. MEPs evoked by focal TMS were recorded in the relaxed opponens pollicis muscle and the size of the conditioned responses

Carlo Trompetto; Alessandro Buccolieri; Giovanni Abbruzzese

2001-01-01

381

Superconducting solenoid model magnet test results  

SciTech Connect

Superconducting solenoid magnets suitable for the room temperature front end of the Fermilab High Intensity Neutrino Source (formerly known as Proton Driver), an 8 GeV superconducting H- linac, have been designed and fabricated at Fermilab, and tested in the Fermilab Magnet Test Facility. We report here results of studies on the first model magnets in this program, including the mechanical properties during fabrication and testing in liquid helium at 4.2 K, quench performance, and magnetic field measurements. We also describe new test facility systems and instrumentation that have been developed to accomplish these tests.

Carcagno, R.; Dimarco, J.; Feher, S.; Ginsburg, C.M.; Hess, C.; Kashikhin, V.V.; Orris, D.F.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.A.; Terechkine, I.; /Fermilab

2006-08-01

382

Self-Organization of Polarized Cell Signaling via Autocrine Circuits: Computational Model Analysis  

SciTech Connect

Recent studies have suggested that autocine signaling through epidermal growth factor receptor (EGFR) might be involved in generating or maintaining an intrinsic polarity in tissue cells, possibly via spatial localization of EGFR-mediated signaling. The difficulty of experimental investigation of autocrine signaling makes especially valuable an application of computational modeling for critical hypotheses about the dynamic operation of the underlying signaling circuits, both intracellular and extracellular. Toward this end, we develop and analyze here a spatially distributed dynamic computational model of autocrine EGFR signaling.

Maly, Ivan V.; Wiley, H S.; Lauffenburger, Douglas A.

2004-01-31

383

Strategy Levels for Guiding Discussion to Promote Explanatory Model Construction in Circuit Electricity  

NSDL National Science Digital Library

A framework for describing and tracking the whole-class discussion-based teaching strategies used by a teacher to support students' construction and development of explanatory models for concepts in circuit electricity is described. A new type of diagram developed to portray teacher-student discourse patterns facilitated the identification of two distinct types, or levels, of teaching strategies: 1) those that support dialogical or conversational elements of classroom interaction; and 2) those that support cognitive model construction processes. The latter include the higher-level goals of promoting a cycle of Observation, model Generation, model Evaluation, and model Modification. While previous studies have focused primarily on the dialogical strategies that are essential for fostering communication as an enabling condition, the cognitive strategies identified herein are aimed at fostering conceptual model construction.

Williams, E. G.; Clement, John J.

2007-11-25

384

Geometrically Frustrated Magnets as Model Systems.  

National Technical Information Service (NTIS)

The specific aim of this research program has been to understand the cooperative magnetic properties of geometrically frustrated antiferromagnets which are model frustrated systems. We have performed extensive thermal studies of one such material, gadolin...

P. Schiffer

2001-01-01

385

Numerical modeling of high-voltage circuit breaker arcs and their interraction with the power system  

NASA Astrophysics Data System (ADS)

In this work the interaction between series connected gas and vacuum circuit breaker arcs has been studied. The breakdown phenomena in vacuum interrupters during the post arc current period have been of special interest. Numerical models of gas and vacuum arcs were developed in the form of black box models. Especially, the vacuum post arc model was implemented by combining the existing transition model with an ion density function and expressions for the breakdown mechanisms. The test series studied reflect that for electric fields on the order of 10sp7V/m over the anode, the breakdown of the vacuum gap can result from a combination of both thermal and electrical stresses. For a particular vacuum device, the vacuum model helps to find the interruption limits of the electric field and power density over the anode. The series connection of gas and vacuum interrupters always performs better than the single gas device. Moreover, to take advantage of the good characteristics of both devices, the time between the current zero crossing in each interrupter can be changed. This current zero synchronization is controlled by changing the capacitance in parallel to the gas device. This gas/vacuum interrupter is suitable for interruption of very stressful short circuits in which the product of the dI/dt before current zero and the dV/dt after current zero is very high. Also, a single SF6 interrupter can be replaced by an air circuit breaker of the same voltage rating in series with a vacuum device without compromising the good performance of the SF6 device. Conceptually, a series connected vacuum device can be used for high voltage applications with equal distribution of electrical stresses between the individual interrupters. The equalization can be made by a sequential opening of the individual contact pairs, beginning with the interruptors that are closer to ground potential. This could eliminate the use of grading capacitors.

Orama, Lionel R.

386

Simulation of electric power circuit breakers in the EMTP incorporating electric arc models: application to reactor bank switching and short line fault  

Microsoft Academic Search

Up to now in the electromagnetic transient program (EMTP) the electromagnetic transients caused by circuit breaker switching have been simulated using the ideal circuit breaker model. In this paper the authors incorporate the EMTP nonlinear electric arc models in the simulation of power circuit breakers, in different extinction means and different work. Applications for reactor bank switching and short line

C. Ramirez; P. A. Calva

2001-01-01

387

Envelope simulation by SPICE-compatible models of linear electric circuits driven by modulated signals  

Microsoft Academic Search

SPICE-compatible equivalent circuits were developed to facilitate the analysis and envelope simulation of electric circuits driven by modulated signals. The circuits are based on a novel complex phasor-domain transformation. The proposed method facilitates simulation of any general linear circuit driven by a modulated signal such as amplitude modulation, frequency modulation, or phase modulation. Simulation time by the proposed envelope simulation

Shmuel Ben-Yaakov; Stanislav Glozman; Raul Rabinovici

2001-01-01

388

A new type of gradiometer for the receiving circuit of magnetic induction tomography (MIT).  

PubMed

Magnetic induction tomography (MIT) is a low-resolution imaging modality which aims at the three-dimensional (3D) reconstruction of the electrical conductivity in objects from alternating magnetic fields. In MIT systems the magnetic field perturbations to be detected are very small when compared to the excitation field (ppm range). The voltage which is induced by the excitation field in the receiver coils must be suppressed for providing sufficient dynamic range. In the past, two very efficient strategies were proposed: adjusted planar gradiometers (PGRAD) and the orientation of a receiver coil with respect to the excitation coil such that the net magnetic flow is zero (zero flow coil, ZFC). In contrast to the PGRAD no voltage is induced in the ZFC by the main field. This is advantageous because two comparatively high voltages in the two gradiometer coils can never be subtracted perfectly, thus leaving a residual voltage which is prone to drift. However, a disadvantage of the ZFC is the higher susceptibility to interferences from far RF sources. In contrast, in the gradiometer such interferences are cancelled to a high degree. We developed a new type of gradiometer (zero flow gradiometer, ZFGRAD) which combines the advantages of ZFC and PGRAD. All three systems were compared with respect to sensitivity and perturbation to signal ratio (PSR) defined as the ratio of the signal change due to a magnetic perturbation field at the carrier frequency and the signal change due to shifting a metallic sphere between two test points. The spatial sensitivity of the three systems was found to be very similar. The PSR of the ZFGRAD was more than 12 times lower than that of the ZFC. Finally, the feasibility of image reconstruction with two arrays of eight excitation coils and eight ZFGRAD, respectively, was shown with a single-step Gauss-Newton reconstructor and simulated measurement data generated for a cylindrical tank with a spherical perturbation. The resulting images show a clear, bright feature at the correct position of the sphere and are comparable to those with PGRAD arrays. PMID:15798243

Scharfetter, Hermann; Merwa, Robert; Pilz, Karl

2005-03-29

389

Lumped-element Circuit Model for Single-Dielectric Barrier Discharge Plasma Actuator  

NASA Astrophysics Data System (ADS)

This work presents an extension of our previous studies on a single-dielectric barrier discharge (SDBD) plasma actuators. The space-time lumped-element circuit model that had been developed for the actuator is intended to model the details of the ionization process to provide predictions of the body force for a range of parameters without the need of experimental calibration. In this model, the domain over the covered electrode is divided into several parallel equivalent circuit networks, each consisting of resistive and capacitive elements and zenor diodes. The results of this numerical model show very good agreement with the space-time resolved experimental observations of the plasma illumination over the dielectric surface for a range of applied voltage amplitudes and frequencies. These characteristics include plasma sweep-out velocity and spatial extent, and spatial intensity decay. The model provides the boundary conditions on the electric potential over the dielectric that is needed in solving for the actuator space-time body force. The plasma body force is then used in a Navier-Stokes flow solver to study the effects of the plasma actuator. Examples of simulations with the plasma actuator on a flat surface and the leading edge of an airfoil are presented. The simulations show good agreement with comparable experiments. Supported under a USAF SBIR Phase II Contract FA8650-04-C-3405.

Orlov, Dmitri; Corke, Thomas; Patel, Mehul

2006-11-01

390

A statistical vacuum circuit breaker model for simulation of transient over voltages  

SciTech Connect

A statistical model of a medium voltage vacuum circuit breaker was developed in EMTP by using new powerful TACS MODELS. The model includes the arc voltage characteristic, calculation of mean chopping current value with known di/dt, the dielectric breakdown voltage characteristic, contacts separation dynamics, probability of high frequency arc quenching capability and probability of high frequency (HF) zero current passings. The influence of a switching-off time is studied and a statistical estimation is given of the transient overvoltages expected for a specific network configuration. The relation between the switching-off times and the overvoltages is also presented. In addition to these results the paper includes explanation of the modeling technique in the EMTP for all elements constituting the distribution network and validation of the vacuum breaker model behavior. This approach provides valuable information to engineers constructing metal-enclosed switch gear, electric utilities and other users who are going to install vacuum breakers in medium voltage networks.

Kosmac, J.; Zunko, P. [Univ. of Ljubljana (Slovenia). Faculty of Electrical and Computer Engineering

1995-01-01

391

Modeling of a claw-pole alternator using permeance network coupled with electric circuits  

Microsoft Academic Search

We propose in this paper, a modeling and simulation method of electrical machines by electric-magnetic coupled network, based on the Bond-Graph models and permeance network. The proposed approach allows us to easily take into account nonlinearities such as saturation and simple hysteresis effects, and to obtain forces applied on the teeth, with a simulation time very weak compared to the

M. Hecquet; P. Brochet

1995-01-01

392

Comparison Of Two Methods For Modeling Large-Signal Alternating Magnetic Fields Using Finite-Elements  

Microsoft Academic Search

As part of EPRI Project RP 1288-1 methods have been developed for applying finite element techniques in developing large generator equivalent circuit models. In earlier work, non-steady-state effects have been handled on a linearized basis, invoking the assumption of small signals. This paper describes more elaborate finite element techniques, which include magnetic non-linearities in non-steady-state calculations. The two methods compared

S. H. Minnich; S. C. Tandon; D. R. Atkinson

1984-01-01

393

High-speed characterization and mechanical modeling of microscale, axial-flux, permanent-magnet generators  

Microsoft Academic Search

This paper reports the high-speed experimental characterization of a microscale, axial-flux, permanent-magnet (PM) generator to failure. A single-phase, open-circuit voltage of 0.9 Vrms was measured at 225 krpm, which corresponds to 3.3 W of DC power if the machine were connected via power electronics to a matched resistive load. Finite-element analysis was used to model and examine the mechanical design

David P. Arnold; Yeun-Ho Joung; Iulica Zana; Jin-Woo Park; Sauparna Das; Jeffrey H. Lang; David Veazie; M. G. Allen

2005-01-01

394

A Method for Interfacing Lumped-Circuit Models and Transmission-Line System Models With Application to Railways  

Microsoft Academic Search

Transient analysis of lossy multiconductor transmission lines (MTLs) has been studied using the finite-difference time-domain (FDTD) method with lumped loads\\/devices connected at line terminations. In electrified railway networks, series and shunt devices (whose circuit models are derived either from experiments\\/borrowed off the shelf), e.g., transformers, converters, switchgear, signal equipments, etc., are found distributed along the MTL system. To simulate such

Ziya Mazloom; Nelson Theethayi; Rajeev Thottappillil

2009-01-01

395

An improved electrical and thermal model of a microbolometer for electronic circuit simulation  

NASA Astrophysics Data System (ADS)

The need for uncooled infrared focal plane arrays (IRFPA) for imaging systems has increased since the beginning of the nineties. Examples for the application of IRFPAs are thermography, pedestrian detection for automotives, fire fighting, and infrared spectroscopy. It is very important to have a correct electro-optical model for the simulation of the microbolometer during the development of the readout integrated circuit (ROIC) used for IRFPAs. The microbolometer as the sensing element absorbs infrared radiation which leads to a change of its temperature due to a very good thermal insulation. In conjunction with a high temperature coefficient of resistance (TCR) of the sensing material (typical vanadium oxide or amorphous silicon) this temperature change results in a change of the electrical resistance. During readout, electrical power is dissipated in the microbolometer, which increases the temperature continuously. The standard model for the electro-optical simulation of a microbolometer includes the radiation emitted by an observed blackbody, radiation emitted by the substrate, radiation emitted by the microbolometer itself to the surrounding, a heat loss through the legs which connect the microbolometer electrically and mechanically to the substrate, and the electrical power dissipation during readout of the microbolometer (Wood, 1997). The improved model presented in this paper takes a closer look on additional radiation effects in a real IR camera system, for example the radiation emitted by the casing and the lens. The proposed model will consider that some parts of the radiation that is reflected from the casing and the substrate is also absorbed by the microbolometer. Finally, the proposed model will include that some fraction of the radiation is transmitted through the microbolometer at first and then absorbed after the reflection at the surface of the substrate. Compared to the standard model temperature and resistance of the microbolometer can be modelled more realistically when these higher order effects are taken into account. A Verilog-A model for electronic circuit simulations is developed based on the improved thermal model of the microbolometer. Finally, a simulation result of a simple circuit is presented.

Würfel, D.; Vogt, H.

2012-09-01

396

Design for a New Signal Analyzer through a Circuit Modeling Simulation as a One Body System for SAC's  

SciTech Connect

A circuit simulation analysis and diagnosis methods are used to diagnose instruments in detail when they give apparently abnormal readings. In this paper, a new simulator for analyzing the modeling of important circuits under SACs(severe accident conditions) has been designed. The realization of a one body system by using a one order command system in the LabVIEW and Pspice was used instead of a complex two body system. The program shows the output data from the circuit modeling according to a one order command system. The procedure for the simulator design was divided into two steps, of which the first step was the design of the diagnosis methods, and the second step was a circuit simulator for the signal processing tool and the special signal analysis tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen. (authors)

Kil-Mo, Koo; Sang-Baik, Kim; Hee-Dong, Kim [Department of Thermal-Hydraulic Safety Research Team, KAERI, 150 Dukjin-dong, Yuseong, Daejeon, 305-353 (Korea, Republic of); Hae-Yong, Kang [Semiconductor Research Institute, Korea University, Daejeon (Korea, Republic of)

2006-07-01

397

Modeling of non-uniform device geometries for post-lithography circuit analysis  

NASA Astrophysics Data System (ADS)

Current ORC and LRC tools are not connected to design in any way. They are pure shape-based functions. A wafer-shape based power and performance signoff is desirable for RET validation as well as for "closest-to-silicon" analysis. The printed images (generated by lithography simulation) are not restricted to simple rectilinear geometries. There may be other sources of such irregularities such as Line Edge Roughness (LER). For instance, a silicon image of a transistor may not be a perfect rectangle as is assumed by all current circuit analysis tools. Existing tools and device models cannot handle complicated non-rectilinear geometries. In this paper, we present a novel technique to model non-uniform, non-rectilinear gates as equivalent perfect rectangle gates so that they can be analyzed by SPICE-like circuit analysis tools. The effect of threshold voltage variation along the width of the device is shown to be significant and is modeled accurately. Taking this effect into account, we find the current density at every point along the device and integrate it to obtain the total current. The current thus calculated is used to obtain the effective length for the equivalent rectangular device. We show that this method is much more accurate than previously proposed approaches which neglect the location dependence of the threshold voltage.

Gupta, Puneet; Kahng, Andrew; Kim, Youngmin; Shah, Saumil; Sylvester, Dennis

2006-04-01

398

A Modal-Based Iterative Circuit Model for the Analysis of CRLH Leaky-Wave Antennas Comprising Periodically Loaded PPW  

Microsoft Academic Search

A novel modal-based iterative circuit model is de- scribed for the calculation of the complex propagation constant of mushroom-like parallel-plate composite right\\/left handed leaky-wave antennas (PPW CRLH LWAs). The conventional lossless CRLH unit cell circuit is modified in order to consider the electromagnetic coupling to free space through a slot. For this pur- pose, a slot equivalent radiative structure, based

Juan Sebastian Gomez-Diaz; Alejandro Alvarez-Melcon; Thomas Bertuch

2011-01-01

399

Modelling studies on the computational function of fast temporal structure in cortical circuit activity.  

PubMed

The interplay between modelling and experimental studies can support the exploration of the function of neuronal circuits in the cortex. We exemplify such an approach with a study on the role of spike timing and gamma-oscillations in associative memory in strongly connected circuits of cortical neurones. It is demonstrated how associative memory studies on different levels of abstraction can specify the functionality to be expected in real cortical neuronal circuits. In our model overlapping random configurations of sparse cell populations correspond to memory items that are stored by simple Hebbian coincidence learning. This associative memory task will be implemented with biophysically well tested compartmental neurones developed by Pinsky and Rinzel . We ran simulation experiments to study memory recall in two network architectures: one interconnected pool of cells, and two reciprocally connected pools. When recalling a memory by stimulating a spatially overlapping set of cells, the completed pattern is coded by an event of synchronized single spikes occurring after 25-60 ms. These fast associations are performed even at a memory load corresponding to the memory capacity of optimally tuned formal associative networks (>0.1 bit/synapse). With tonic stimulation or feedback loops in the network the neurones fire periodically in the gamma-frequency range (20-80 Hz). With fast changing inputs memory recall can be switched between items within a single gamma cycle. Thus, oscillation is not a primary coding feature necessary for associative memory. However, it accompanies reverberatory feedback providing an improved iterative memory recall completed after a few gamma cycles (60-260 ms). In the bidirectional architecture reverberations do not express in a rigid phase locking between the pools. For small stimulation sets bursting occurred in these cells acting as a supportive mechanism for associative memory. PMID:11165914

Sommer, F T; Wennekers, T

400

Trading Speed and Accuracy by Coding Time: A Coupled-circuit Cortical Model  

PubMed Central

Our actions take place in space and time, but despite the role of time in decision theory and the growing acknowledgement that the encoding of time is crucial to behaviour, few studies have considered the interactions between neural codes for objects in space and for elapsed time during perceptual decisions. The speed-accuracy trade-off (SAT) provides a window into spatiotemporal interactions. Our hypothesis is that temporal coding determines the rate at which spatial evidence is integrated, controlling the SAT by gain modulation. Here, we propose that local cortical circuits are inherently suited to the relevant spatial and temporal coding. In simulations of an interval estimation task, we use a generic local-circuit model to encode time by ‘climbing’ activity, seen in cortex during tasks with a timing requirement. The model is a network of simulated pyramidal cells and inhibitory interneurons, connected by conductance synapses. A simple learning rule enables the network to quickly produce new interval estimates, which show signature characteristics of estimates by experimental subjects. Analysis of network dynamics formally characterizes this generic, local-circuit timing mechanism. In simulations of a perceptual decision task, we couple two such networks. Network function is determined only by spatial selectivity and NMDA receptor conductance strength; all other parameters are identical. To trade speed and accuracy, the timing network simply learns longer or shorter intervals, driving the rate of downstream decision processing by spatially non-selective input, an established form of gain modulation. Like the timing network's interval estimates, decision times show signature characteristics of those by experimental subjects. Overall, we propose, demonstrate and analyse a generic mechanism for timing, a generic mechanism for modulation of decision processing by temporal codes, and we make predictions for experimental verification.

Standage, Dominic; You, Hongzhi; Wang, Da-Hui; Dorris, Michael C.

2013-01-01

401

Behavioural model of Spin Torque Transfer Magnetic Tunnel Junction, Using Verilog-A  

NASA Astrophysics Data System (ADS)

A novel simple and efficient model of Spin Torque Transfer Magnetic Tunnel Junction (STT-MTJ) is presented. The model is implemented using Verilog-A. The model accurately emulates the main properties of an STT-MTJ which includes Tunnel Magneto resistance Ratio (TMR), its dependence on the voltage bias and the Critical switching current. The novelty of the model lies in the fact that the voltage dependence of TMR has been modeled using a single equation dividing it into three different operating regions. A register based on the model is also developed. The model can be used for faster simulations of hybrid Magnetic CMOS circuits and in various other wide range of applications. The models were verified using Synopsys Hspice 2010.

Garg, Rishubh; Kumar, Deepak; Jindal, Navneet; Negi, Nandita; Ahuja, Chetna

2012-11-01

402

LDRD Final Report - Investigations of the impact of the process integration of deposited magnetic films for magnetic memory technologies on radiation-hardened CMOS devices and circuits - LDRD Project (FY99)  

Microsoft Academic Search

This project represented a coordinated LLNL-SNL collaboration to investigate the feasibility of developing radiation-hardened magnetic non-volatile memories using giant magnetoresistance (GMR) materials. The intent of this limited-duration study was to investigate whether giant magnetoresistance (GMR) materials similar to those used for magnetic tunnel junctions (MTJs) were process compatible with functioning CMOS circuits. Sandia's work on this project demonstrated that deposition

DAVID R. MYERS; JEFFREY R. JESSING; OLGA B. SPAHN; MARTY R. SHANEYFELT

2000-01-01

403

Magnetic Dipole Field 3D Model  

NSDL National Science Digital Library

The Magnetic Dipole Field 3D Model displays the field lines and field vectors of a dipole located at the origin and oriented along the z-axis. Users can compute the field line passing through a point by dragging the a marker within the 3D view. Users can also visualize the field vectors in a plane passing though the center of the dipole. The Magnetic Dipole Field 3D Model was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_em_MagneticDipole3D.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models.

Christian, Wolfgang

2012-08-11

404

Exact Circuit Performance Validation  

Microsoft Academic Search

\\u000a In Chapter 4, we discussed computing the exact delays of combinational and sequential circuits. This analysis is performed\\u000a on circuits with known or assumed gate delay models, e.g. [dmin dinar], and is used mainly to predict delays or performances\\u000a of designs. When designs are fabricated into physical circuits, the delays of the circuits will agree with the delay analyses\\u000a of

William K. C. Lam; Robert K. Brayton

405

Testing, design and modeling issues in radiation-hardened CMOS integrated circuits  

NASA Astrophysics Data System (ADS)

Continued research and greater understanding of ionization damage mechanisms in silicon/silicon dioxide structures will lead to improved total dose modeling techniques and a better definition of proper total dose testing conditions. Combining computer models with laboratory test data will allow engineers to predict the total dose response of components for irradiation periods ranging from years to less than a second. Recent progress in the understanding of dose-rate phenomena in integrated circuits has identified Rail Span Collapse as a possible upset mechanism. Use of this model aids the design of ICs expected to have an upset level above 1E10 rad(Si)/sec. Further research into photo current generation, rail span collapse, and local upset mechanisms will allow maximization of IC upset levels.

Gover, J. E.; Ackermann, M. R.

406

A short channel charge LDD-MOSFET model for analog and digital circuits with low overdrive voltage  

Microsoft Academic Search

A charge LDD-MOSFET model, based on an analytical surface potential formulation at source and drain, for all channel lengths down to deep submicron has been derived and implemented in the circuit simulator SABER. In contrast to all hitherto developed models, this model takes the geometrical dependence of threshold voltage caused by the space charge regions at source and drain (SC-effect)

P. Klein; K. Hoffmann; B. Lemaitre

1995-01-01

407

Modeling Magnetic Field Topology at Jupiter with the Khurana Magnetic Field Model  

NASA Astrophysics Data System (ADS)

To explore the degree of coupling between the interplanetary magnetic field (IMF) and Jupiter's magnetosphere, we traced magnetic field lines from the polar region of the planet using the Khurana [1997, 2005] magnetic field model. We used a parameterized definition of the Jovian magnetopause created by Joy et al. [2002] that varies with the value of the solar wind dynamic pressure. We searched for field lines that cross the magnetopause and that potentially connect to the interplanetary magnetic field. We further explored the variation on magnetic field structure with local time orientation of Jupiter's dipole (i.e. Central Meridian Longitude) as well as upstream solar wind and IMF conditions.

Cohen, I.; Bagenal, F.

2008-12-01

408

A RF Graphene FET Large-Signal Compact Model Compatible with Circuit Simulators  

NASA Astrophysics Data System (ADS)

Graphene, a one-dimensional array of carbon atoms, is a unique material which has yet to be fully utilized. It is being investigated for its applications in the digital, analog, and high frequency (RF) domains. While it lacks a natural bandgap, rendering it unsuitable for digital circuitry without additional modification of electrical characteristics, graphene is applicable to a wide spectrum of RF applications ranging from communications platforms to flexible electronics. Specifically, its use in building RF field-effect transistors (FETs) can lead to better performance metrics, higher bandwidths, and faster data transmission rates. Graphene FETs (GFETs) are attractive because the graphene channel can be grown over large-area surfaces, and the devices typically exhibit high electron and hole mobilities and high achievable current densities [1]. In order to bridge the gap between device simulation and circuit design, a closed-form large-signal compact model compatible with commercially available circuit simulators is desired. The primary investigation of this study is to develop such a model and to evaluate its accuracy with measured and simulated data.

Trocchia, Scott M.

409

Modeling integrated photovoltaic-electrochemical devices using steady-state equivalent circuits  

PubMed Central

We describe a framework for efficiently coupling the power output of a series-connected string of single-band-gap solar cells to an electrochemical process that produces storable fuels. We identify the fundamental efficiency limitations that arise from using solar cells with a single band gap, an arrangement that describes the use of currently economic solar cell technologies such as Si or CdTe. Steady-state equivalent circuit analysis permits modeling of practical systems. For the water-splitting reaction, modeling defines parameters that enable a solar-to-fuels efficiency exceeding 18% using laboratory GaAs cells and 16% using all earth-abundant components, including commercial Si solar cells and Co- or Ni-based oxygen evolving catalysts. Circuit analysis also provides a predictive tool: given the performance of the separate photovoltaic and electrochemical systems, the behavior of the coupled photovoltaic–electrochemical system can be anticipated. This predictive utility is demonstrated in the case of water oxidation at the surface of a Si solar cell, using a Co–borate catalyst.

Winkler, Mark T.; Cox, Casandra R.; Nocera, Daniel G.; Buonassisi, Tonio

2013-01-01

410

Optimization of resonant power supply circuit  

Microsoft Academic Search

A resonant power supply has been proposed to power rapid cycling accelerator magnets. In the present work, the resonant power supply circuit is optimized by selecting the most feasible choke inductance. For this optimization, a computer model and an approximate design method were developed. The effect of choke inductance on the component's rating and cost was determined. It was found

G. G. Karady; H. A. Thiessen

1989-01-01

411

Circuit Simulation of Genetic Networks  

Microsoft Academic Search

Genetic networks with tens to hundreds of genes are difficult to analyze with currently available techniques. Because of the many parallels in the function of these biochemically based genetic circuits and electrical circuits, a hybrid modeling approach is proposed that integrates conventional biochemical kinetic modeling within the frame-work of a circuit simulation. The circuit diagram of the bacteriophage lambda lysis-lysogeny

Harley H. McAdams; Lucy Shapiro

1995-01-01

412

Quantum Circuits and Schrödinger's Cat States  

NASA Astrophysics Data System (ADS)

Quantum systems that are confined to circuit geometries are called quantum circuits. Macroscopic superconducting circuits are quantum circuits which can be modelled using a Quantisation by Parts scheme based on the macroscopic wave function approach of Feynman. This paper studies the circuit composed of an input wire and an output plate. We find that in order to achieve a consistent theory of supercurrent flow we have to generalize the quantisation by parts scheme to quantise in a path space. The generalized theory predicts a current flow down the wire into the plane. In addition to a current flowing radially outwards in the plane, the theory allows a circulating current round the origin. Strikingly, the circulating current can flow clockwise or anti-clockwise in such a way as to generate a magnetic moment of magnitude half of a Bohr magneton for an orbiting electron in an atom and a magnetic flux half that of the magnetic flux quantum of a superconducting ring. There is also the possibility of a macroscopic superposition of the two states of opposing circulating currents resembling a Schrödinger’s cat situation. Furthermore, we outline a setup involving an external magnetic field that may allow experimental tests of the theory.

Wan, K. K.; Menzies, D.

2009-01-01

413

Analyzing the Inherent Reliability of Moderately Sized Magnetic and Electrostatic QCA Circuits Via Probabilistic Transfer Matrices  

Microsoft Academic Search

As computing technology delves deeper into the nanoscale regime, reliability is becoming a significant concern, and in response, Teramac-like systems will be the model for many early non-CMOS nanosystems. Engineering systems of this type requires understanding the inherent reliability of both the functional cells and the interconnect used to build the system, and which components are most critical. One particular

Timothy J. Dysart; Peter M. Kogge

2009-01-01

414

Magnetization model for a Heusler alloy  

NASA Astrophysics Data System (ADS)

Close to room temperature, the off-stoichiometric Ni50Mn35In15 Heusler alloy is known to undergo a first-order magnetostructural transition. This paper presents a new model that closely mimics the magnetic behavior of the virgin curve and that of the M-H loops within the temperature range where the alloy undergoes the first-order transition. The virgin curve and the M-H loops relevant to the model were measured at 280 K. Since our data show that 280 K is above the start of the transition, it implies that at this temperature the alloy is in a mixed state. The mixed state refers the presence of two distinct magnetic states. The model and mechanism we propose to explain the complex magnetic behavior of the virgin curve and of the M-H loops pertain to the action of the applied field on the transition between the two magnetic states. Both the model and the proposed mechanism provide new insight about the complex magnetic behavior displayed by the Ni50Mn35In15 alloy within the first-order transition.

Provenzano, Virgil; Della Torre, Edward; Bennett, Lawrence H.

2013-05-01

415

Trajectories in Electric and Magnetic Fields Model  

NSDL National Science Digital Library

The Trajectories in Electric and Magnetic Fields model computes a family of trajectories of charges emitted from a point source isotropically and with the same energy. These trajectories create focal points and caustic surfaces meeting the symmetry line in conical cusps. The simulation enables users to study these trajectories in both crossed and parallel magnetic fields. The user can vary the initial particle velocity and the field strengths. The Trajectories in Electric and Magnetic Fields model was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item.

Christian, Wolfgang

2012-10-25

416

An optimal design of high performance interface circuit with acoustic transducer model  

Microsoft Academic Search

Reducing interface circuit power consumption without compromising low noise performance is an increasing challenge for portable sensor applications. Thus paper reports a high power efficiency and high SNR capacitive MEMS microphone interface circuit using a negative feedback amplifier. The transistors in the interface circuit are biased in the deep subthreshold region, for a 45% better figure of merit (FoM) that

Yu-Chun Hsu; Jen-Yi Chen; Tamal Mukherjee; Gary K. Fedder

2007-01-01

417

A Fault Model and a Test Method for Analog Fuzzy Logic Circuits  

Microsoft Academic Search

A nalog circuit im plem entations of fuz zy logic are characteriz ed by perform ing logical connectives of analog signals. They can be considered as generaliz ation of digital circuits to a range of logical values, thus form ing a special class of analog circuits. The idea of this w ork is to exploit this relationship for testing. For

Stefan Weiner

1995-01-01

418

Changes in expectation consequent on experience, modeled by a simple, forgetful neural circuit.  

PubMed

Our expectation of an event such as a visual stimulus clearly depends on previous experience, but how the brain computes this expectation is currently not fully understood. Because expectation influences the time to respond to a stimulus, we arranged for the probability of a visual target to suddenly change and found that the time taken to make an eye movement to it then changed continuously, eventually stabilizing at a level reflecting the new probability. The time course of this change can be modeled making a simple assumption: that the brain discounts old information about the probability of an event by a factor lambda, relative to new information. The value of lambda presumably represents a compromise between responding rapidly to genuine changes in the environment and not prematurely discarding information still of value. The model we propose may be implemented by a very simple neural circuit composed of only a few neurons. PMID:16895461

Anderson, Andrew J; Carpenter, R H S

2006-07-24

419

Model of a magnetic field in poloidal divertor tokamaks affected by resonant magnetic perturbations  

Microsoft Academic Search

A generic analytical model for the description of magnetic field lines in poloidal divertor tokamaks in the presence of external resonant magnetic perturbations is proposed. It is based on the Hamiltonian description of magnetic field lines in tokamaks. The safety factor and the spectra of magnetic perturbations are chosen by the requirement to satisfy their generic behavior near the magnetic

S. S. Abdullaev

2009-01-01

420

Finite element analysis in electromagnetic systems-accounting for electric circuits  

Microsoft Academic Search

Two approaches for the numerical simulation of electromagnetic systems, accounting for electric circuit equations, are presented. First, the indirect coupled model, which permits the simulation of synchronous machines fed by controlled inverters with moderate calculation time is considered. Second, a direct coupled model where the magnetic and electric circuit equations (2-D or 3-D) are solved simultaneously is developed. This approach

Francis Piriou; Adel Razek

1993-01-01

421

Computer simulation of the transient behaviour of a fluxgate magnetometric circuit  

NASA Astrophysics Data System (ADS)

Simulated circuits contain a fluxgate sensor. The cores are modelled by the Jiles-Atherton model. Relevant wave forms are presented. The wave form of the excitation current is studied assuming an excitation frequency sweep. We also study the behaviour of the circuit for an ac low-frequency external applied magnetic field.

Moldovanu, B.-O.; Moldovanu, C.; Moldovanu, A.

1996-05-01

422

Phase Resetting and Phase Locking in Hybrid Circuits of One Model and One Biological Neuron  

PubMed Central

To determine why elements of central pattern generators phase lock in a particular pattern under some conditions but not others, we tested a theoretical pattern prediction method. The method is based on the tabulated open loop pulsatile interactions of bursting neurons on a cycle-by-cycle basis and was tested in closed loop hybrid circuits composed of one bursting biological neuron and one bursting model neuron coupled using the dynamic clamp. A total of 164 hybrid networks were formed by varying the synaptic conductances. The prediction of 1:1 phase locking agreed qualitatively with the experimental observations, except in three hybrid circuits in which 1:1 locking was predicted but not observed. Correct predictions sometimes required consideration of the second order phase resetting, which measures the change in the timing of the second burst after the perturbation. The method was robust to offsets between the initiation of bursting in the presynaptic neuron and the activation of the synaptic coupling with the postsynaptic neuron. The quantitative accuracy of the predictions fell within the variability (10%) in the experimentally observed intrinsic period and phase resetting curve (PRC), despite changes in the burst duration of the neurons between open and closed loop conditions.

Oprisan, S. A.; Prinz, A. A.; Canavier, C. C.

2004-01-01

423

Phase resetting and phase locking in hybrid circuits of one model and one biological neuron.  

PubMed

To determine why elements of central pattern generators phase lock in a particular pattern under some conditions but not others, we tested a theoretical pattern prediction method. The method is based on the tabulated open loop pulsatile interactions of bursting neurons on a cycle-by-cycle basis and was tested in closed loop hybrid circuits composed of one bursting biological neuron and one bursting model neuron coupled using the dynamic clamp. A total of 164 hybrid networks were formed by varying the synaptic conductances. The prediction of 1:1 phase locking agreed qualitatively with the experimental observations, except in three hybrid circuits in which 1:1 locking was predicted but not observed. Correct predictions sometimes required consideration of the second order phase resetting, which measures the change in the timing of the second burst after the perturbation. The method was robust to offsets between the initiation of bursting in the presynaptic neuron and the activation of the synaptic coupling with the postsynaptic neuron. The quantitative accuracy of the predictions fell within the variability (10%) in the experimentally observed intrinsic period and phase resetting curve (PRC), despite changes in the burst duration of the neurons between open and closed loop conditions. PMID:15454430

Oprisan, S A; Prinz, A A; Canavier, C C

2004-10-01

424

Measuring circuit  

DOEpatents

An automatic gain control circuit functions to adjust the magnitude of an input signal supplied to a measuring circuit to a level within the dynamic range of the measuring circuit while a log-ratio circuit adjusts the magnitude of the output signal from the measuring circuit to the level of the input signal and optimizes the signal-to-noise ratio performance of the measuring circuit.

Sun, Shan C. (Pittsburgh, PA); Chaprnka, Anthony G. (Cockeysville, MD)

1977-01-11

425

A new modeling of the vector magnetic property  

Microsoft Academic Search

This paper presents a new modeling of the vector magnetic property with an integration term. Recently, the studies of the two-dimensional (2-D) magnetic property have made progress rapidly and the achievements have become a center of attention. The 2-D magnetic measuring technique shows us practical vector constitutive relations in magnetic materials. We enable the magnetic field analysis, which considered the

Hiroyasu Shimoji; Masato Enokizono; Takashi Todaka; Tatsuya Honda

2002-01-01

426

Equivalent Circuit Modeling of a Multilayer Planar Winding Array Structure for Use in a Universal Contactless Battery Charging Platform  

Microsoft Academic Search

In this paper, an equivalent circuit model of a multilayer planar winding array structure that can be used as a universal contactless battery charging platform is presented. This model includes the mutual-inductive effects of partial overlaps of planar windings in the multilayer structure. It has been successfully simulated with PSpice and practically verified with measurements obtained from three prototypes. This

Xun Liu; S. Y. Ron Hui

2007-01-01

427

A hybrid model by clustering and evolving fuzzy rules for sales decision supports in printed circuit board industry  

Microsoft Academic Search

This research develops a hybrid model by integrating Self Organization Map (SOM) neural network, Genetic Algorithms (GA) and Fuzzy Rule Base (FRB) to forecast the future sales of a printed circuit board factory. This hybrid model encompasses two novel concepts: (1) clustering an FRB into different clusters, thus the interaction between fuzzy rules is reduced and a more accurate prediction

Pei-chann Chang; Chen-hao Liu; Yen-wen Wang

2006-01-01

428

Detection and identification of ore grindability in a semiautogenous grinding circuit model using wavelet transform variances of measured variables  

Microsoft Academic Search

A reduced dimension dynamic model subject to random disturbances for a semiautogenous grinding (SAG) circuit is developed that is able to handle changes in the characteristics of the new feed ore. This dynamic model, which is adjusted using data from a large mineral processing plant, has been developed with the objective of being useful for design and testing of fault

G. D. Gonzalez; D. Miranda; A. Casali; G. Vallebuona

2008-01-01

429

MODELING AND SIMULATION OF THE PRIMARY CIRCUIT OF THE PAKS NUCLEAR POWER PLANT FOR CONTROL AND DIAGNOSIS  

Microsoft Academic Search

Two related but different dynamic simulators of the primary circuit of the Paks Nuclear Power Plant in Hungary are described in this paper that have been built from a simple dynamic model based on first engineering principles. For dynamic analysis and controller design purposes a simple continuous time discrete-continuous hybrid state-space model has been developed that is implemented in the

Erzsébet Németh; Csaba Fazekas; Gábor Szederkényi; Katalin M. Hangos

430

Derivation of a continuum model and its electric equivalent-circuit representation for ionic polymer–metal composite (IPMC) electromechanics  

Microsoft Academic Search

Biomedical engineering applications of ionic polymer–metal composites such as motion devices for endoscopy, pumps, valves, catheter navigation mechanisms and spinal pressure sensors make it important to properly model IPMCs for engineering design. In particular, IPMC continuum models and their electric equivalent circuit representation are critical to a more efficient design of IPMC devices. In this paper, we propose a new

P. J. Costa Branco; J. A. Dente

2006-01-01

431

Model of the electromagnetic fields inside a cuboidal enclosure populated with conducting planes or printed circuit boards  

Microsoft Academic Search

We examine the extension of a simple and versatile model of the electromagnetic fields in an equipment enclosure with an aperture to include the effects of loading the enclosure with conducting planes or printed circuit board structures (PCB). Modeling results are compared with experimental measurements of the shielding effectiveness in a cuboidal enclosure loaded with both grounded and ungrounded conducting

David W. P. Thomas; Alan C. Denton; Tadeusz Konefal; Trevor Benson; Christos Christopoulos; John F. Dawson; Andy Marvin; Stuart J. Porter; Phillip Sewell

2001-01-01

432

Parameter Estimation for a Model of Gap Gene Circuits with Time-Variable External Inputs in Drosophila.  

National Technical Information Service (NTIS)

We study a model for spatio-temporal pattern formation of gap gene products in the early development of Drosophila. In contrast to previous studies of gap gene circuits, our model incorporates a number of proteins as time-variable external inputs, includi...

M. Ashyraliyev

2009-01-01

433

Modelling the Connection of Alternative Energy Sources to the Three-phase Utility Grid for Circuit Simulation  

Microsoft Academic Search

The paper proposes a model for the practical circuit needed to interface a VSI to the three-phase utility grid for connection of alternative energy sources. The model is deduced by considering both the inverter and grid voltages as being constituted by a superposition of modal (differential and omopolar) components. This approach allows identifying a transfer function of the interface, whose

Federico Scapino

2006-01-01

434

Modelisation and Optimization of Clutch Magnet Actuator Topologies  

Microsoft Academic Search

This paper presents the study of clutch magnet actuators. Two topologies, considering different magnetic constraints of saturation are designed in order to generate powerful engaging force in a limited volume. The magnetic models are based on a reluctance equivalent magnetic circuit considering the magnet flux leakages. The model results are then compared and validated with finite element computations and measurements

V. Pauvert; N. Bernard; M. E. Zaim; J. Bonnefous

2007-01-01

435

A KLM-circuit model of a multi-layer transducer for acoustic bladder volume measurements.  

PubMed

In a preceding study a new technique to non-invasively measure the bladder volume on the basis of non-linear wave propagation was validated. It was shown that the harmonic level generated at the posterior bladder wall increases for larger bladder volumes. A dedicated transducer is needed to further verify and implement this approach. This transducer must be capable of both transmission of high-pressure waves at fundamental frequency and reception of up to the third harmonic. For this purpose, a multi-layer transducer was constructed using a single element PZT transducer for transmission and a PVDF top-layer for reception. To determine feasibility of the multi-layer concept for bladder volume measurements, and to ensure optimal performance, an equivalent mathematical model on the basis of KLM-circuit modeling was generated. This model was obtained in two subsequent steps. Firstly, the PZT transducer was modeled without PVDF-layer attached by means of matching the model with the measured electrical input impedance. It was validated using pulse-echo measurements. Secondly, the model was extended with the PVDF-layer. The total model was validated by considering the PVDF-layer as a hydrophone on the PZT transducer surface and comparing the measured and simulated PVDF responses on a wave transmitted by the PZT transducer. The obtained results indicated that a valid model for the multi-layer transducer was constructed. The model showed feasibility of the multi-layer concept for bladder volume measurements. It also allowed for further optimization with respect to electrical matching and transmit waveform. Additionally, the model demonstrated the effect of mechanical loading of the PVDF-layer on the PZT transducer. PMID:16875709

Merks, E J W; Borsboom, J M G; Bom, N; van der Steen, A F W; de Jong, N

2006-06-06

436

Magnetic flux tube models in superstring theory  

Microsoft Academic Search

Superstring models describing curved 4-dimensional magnetic flux tube backgrounds are exactly solvable in terms of free fields. We first consider the simplest model of this type (corresponding to a ‘Kaluza-Klein’ a = ?3 Melvin background). Its 2d action has a flat but topologically non-trivial 10-dimensional target space (there is a mixing of the angular coordinate of the 2-plane with an

J. G. Russo; A. A. Tseytlin

1996-01-01

437

Feedback and sensitivity in an electrical circuit: An analog for climate models  

SciTech Connect

Earth's climate sensitivity is often interpreted in terms of feedbacks that can alter the sensitivity from that of a no-feedback Stefan-Boltzmann radiator, with the feedback concept and algebra introduced by analogy to the use of this concept in the electronics literature. This analogy is quite valuable in interpreting the sensitivity of the climate system, but usage of this algebra and terminology in the climate literature is often inconsistent, with resultant potential for confusion and loss of physical insight. Here a simple and readily understood electrical resistance circuit is examined in terms of feedback theory to introduce and define the terminology that is used to quantify feedbacks. This formalism is applied to the feedbacks in an energy-balance model of Earth's climate and used to interpret the magnitude of feedback in the climate system that corresponds to present estimates of Earth's climate sensitivity.

Schwartz, S.E.

2010-07-27

438

The magnetic fields of Uranus and Neptune: Methods and models  

Microsoft Academic Search

We present new models of the magnetic fields of Uranus and Neptune, based on data provided by the Voyager II magnetic field experiment. We find the simplest models that satisfy the data, and use the observed surface heat flow as a constraint on the magnetic field structure. Our models are similar to the previously described Q3 and O8 models far

Richard Holme; Jeremy Bloxham

1996-01-01

439

A New Method for Modeling Marine Gravity and Magnetic Anomalies  

Microsoft Academic Search

irregular crustal model as observed on a plane above the material. It is shown how the method can be used to invert the magnetic field data to obtain a magnetization model, but the model so obtained is not unique. The normal restrictions placed on the magnetization models lead to a family of solutions with one degree of freedom. This paper

Robert L. Parker

1974-01-01

440

Quark matter under strong magnetic fields in chiral models  

NASA Astrophysics Data System (ADS)

The chiral model is used to describe quark matter under strong magnetic fields and is compared to other models, the MIT bag model and the two-flavor Nambu-Jona-Lasinio model. The effect of vacuum corrections due to the magnetic field is discussed. It is shown that if the magnetic-field vacuum corrections are not taken into account explicitly, the parameters of the models should be fitted to low-density meson properties in the presence of the magnetic field.

Rabhi, Aziz; Providência, Constança

2011-05-01

441

Three-Phase Model for the Circuit Simulation of Common-Mode Phenomena and Shaft Voltages in AC Motor Drive Systems  

Microsoft Academic Search

The paper presents a circuit simulation model for AC drive systems, including the capacitive and induced shaft voltages that are caused by frequency converters in AC motors. For bearing current analysis, it is essential that the common-mode voltages and currents can be predicted with a sufficient accuracy in an adequate bandwidth. The system model consists of three-phase circuit models for

Petri Mäki-Ontto; Henri Kinnunen; Jorma Luomi

2005-01-01

442

Magnetic Composite Materials and Arbitrary - Relationships  

Microsoft Academic Search

This theoretical study addresses fabricating composite conducting materials with an effective arbitrary B-H relationship in the quasi-static field approximation, exhibiting new magnetic properties. The experimental results demonstrate the possibility of having linear artificial structures with negative effective magnetic permeability. The equivalent circuital model confirms the theoretical and experimental analysis. In particular, following the circuital approach we show how to obtain

Bernardo Tellini; Mauro Bologna

2010-01-01

443

Anti-electromagnetic interference analysis of equivalent circuit of ion channel based on the Hodgkin-Huxley model  

NASA Astrophysics Data System (ADS)

With the continuous improvement of circuit integration and working clock frequency in the electronic system, it is increasingly easy for the system to be affected by electromagnetic waves, and electromagnetic susceptibility and vulnerability become more severe. However, living beings in nature have shown extraordinary compatibility, immunity and adaptability to the electromagnetism at the same time. In addition, the ion channel on the neuron cytomembrane is a typical representation of "bioelectrical immunity". So the Hodgkin-Huxley circuit model with one capacitor in parallel with some power supplies and resistors was adopted to simulate the ion channel on the neuron cytomembrane. Through analysis, the circuit model can be used to simulate some electrical characteristics of biological neuron cells, and then acquire a certain level of anti-electromagnetic interference ability. This method will be useful for improving the reliability, compatibility and anti-interference capability of the electronic system in the complicated electromagnetic environment.

Chu, J.; Chang, X. L.; Zhao, M.; Man, M. H.; Yuan, L.; Wei, M.

2013-03-01

444

Circuit Builder  

NSDL National Science Digital Library

Circuit Builder simulates AC and DC circuits. Circuit Builder can be used in interactive mode (see above) or it can be scripted using JavaScript (see the demo pages). In order for scripting to work, Circuit Builder requires a Java 1.1 capable browser with JavaScript to Java scripting capability.

Van Hoecke, Toon

445

Circuit Sense  

NSDL National Science Digital Library

In this activity about electricity, learners identify closed and open circuits. First, learners examine and label diagrams of open and closed circuits. Then, learners build each of the circuits shown in the diagrams using electrical supplies. Throughout the activity, learners predict and then test if the light bulbs will turn on based on the circuit type.

Extension, University O.

2002-01-01

446

High frequency model of printed-circuit-board based three-winding transformers  

Microsoft Academic Search

An equivalent network of printed-circuit-board (PCB) based three-winding transformers is presented for simulating high frequency behavior (at some MHz). The PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. The use of the multiple secondary outputs can simplify the complementary gate drive circuits that are often required in many

C. M. Arturi; Alessandro GANDELLI; F. Grassi

2002-01-01

447

Modeling Magnetic Flux Emergence in HD 106225  

NASA Astrophysics Data System (ADS)

Using a ``thin flux tube'' approximation proposed by Spruit (1981), and working with a numerical simulation previously used to model solar magnetic flux dynamics, we attempt to create magnetic flux tube emergence in HD 106225, a rapidly rotating subgiant star, which has been observed to have both x-ray emission and starspots. Initial attempts, placing the stellar dynamo at the base of the convection zone, as has been done in solar modeling, were unsuccessful. Fisher, McClymont, & Chou (1991) show that, if the pressure scale height at the base of the convection zone is a significant fraction of the radius at that point (Lambda /R > 0.3), the magnetic tension force increases faster than the buoyancy as the tube is stretched, and no rise occurs from a tube anchored at the base of the convection zone. However, Spruit & van Ballegooijen (1982a, b) prove that, for stars with sufficiently deep convection zones, it is possible to create a buoyantly stable flux tube in the convection zone itself. The stability of a given mode again depends on the value of Lambda /R at a given radius. If Lambda /R > 0.3, a flux tube is able to maintain null buoyancy in the convection zone proper. Using Spruit & van Ballegooijen's solutions, we are able to run numerical simulations that model stable flux tubes in the convection zone. We have also been able to create the rise of a magnetic flux perturbation by placing the base of the ring at a stable convective radius with the perturbation extending to a more buoyant radius. Initial attempts have been based on a simplified model, placing a flux tube at zero latitude with no rotation. We also attempt simulations which allow for flux rise at non-zero latitudes and include Coriolis force. Using these results, we examine the implications that such a magnetic field pattern has for the stellar dynamo.

Wills, M. J.; Deluca, E. E.; Guenther, D. B.

1996-05-01

448

Microdosimetric study for nanosecond pulsed electric fields on a cell circuit model with nucleus.  

PubMed

Recently, scientific interest in electric pulses, always more intense and shorter and able to induce biological effects on both plasma and nuclear membranes, has greatly increased. Hence, microdosimetric models that include internal organelles like the nucleus have assumed increasing importance. In this work, a circuit model of the cell including the nucleus is proposed, which accounts for the dielectric dispersion of all cell compartments. The setup of the dielectric model of the nucleus is of fundamental importance in determining the transmembrane potential (TMP) induced on the nuclear membrane; here, this is demonstrated by comparing results for three different sets of nuclear dielectric properties present in the literature. The results have been compared, even including or disregarding the dielectric dispersion of the nucleus. The main differences have been found when using pulses shorter than 10 ns. This is due to the fact that the high spectral components of the shortest pulses are differently taken into account by the nuclear membrane transfer functions computed with and without nuclear dielectric dispersion. The shortest pulses are also the most effective in porating the intracellular structures, as confirmed by the time courses of the TMP calculated across the plasma and nuclear membranes. We show how dispersive nucleus models are unavoidable when dealing with pulses shorter than 10 ns because of the large spectral contents arriving above 100 MHz, i.e., over the typical relaxation frequencies of the dipolar mechanism of the molecules constituting the nuclear membrane and the subcellular cell compartments. PMID:23595823

Denzi, Agnese; Merla, Caterina; Camilleri, Paola; Paffi, Alessandra; d'Inzeo, Guglielmo; Apollonio, Francesca; Liberti, Micaela

2013-04-18

449

Squishy Circuits  

NSDL National Science Digital Library

Squishy Circuits was developed to teach elementary school children about circuit electricity by letting them build circuits from a PlayDoh-like substance. There are two simple recipes for making the dough: one is conductive and one is insulating. At the simplest level, kids construct a series circuit consisting of one LED, a battery pack, conductive dough, and insulating dough. Learning progresses through parallel circuit construction, motor circuits, buzzer circuits, advanced RGB-LED circuits, and "squishy" animals. All materials are easily acquired, or a kit can be purchased from the website for about $20. Editor's Note: The Squishy Circuits project team has created high-quality videos to accompany the activities. They cover set-up & preparation, LED calculations, tips for teaching the concepts to small children, and directions for building the more advanced circuits.

Thomas, Annmarie

2011-11-25

450

Full vector model for magnetization in sediments  

NASA Astrophysics Data System (ADS)

Sediments provide a continuous record of past geomagnetic field variations. Although it is theoretically possible to get both the direction and intensity of the geomagnetic field from sediment records, the mechanism is not fully understood. Previous workers have postulated that flocculation plays an important role in detrital remanent magnetism (DRM). Flocs are porous, loose and highly fragile aggregates of microscopic clay particles and their behavior in a viscous medium is likely to be different than single particles of magnetic minerals. In order to understand the role of flocculation in sediment magnetization, we carried out a set of redeposition experiments at different field intensities and a quasi-constant field inclination of 45°. We present here a simple numerical model of flocculation, incorporating both magnetic and hydrodynamic torques to explain the experimental data. At small floc sizes DRM acquisition is likely to be non-linear in field strengths comparable to the Earth's, but the sediments may be able to record the directions accurately. With increasing floc sizes sediments may retain a record of the intensity that is linearly related to the applied field or a direction parallel to the applied field, but are unlikely to do both at the same time. Also, the majority of the magnetic particles in the sediments may not be contributing significantly towards the net DRM and any bulk normalizing parameter may be unsuitable if the depositional environment has changed over the depositional period.

Mitra, Ritayan; Tauxe, Lisa

2009-09-01

451

Saltwater Circuit  

NSDL National Science Digital Library

Students build a saltwater circuit, which is an electrical circuit that uses saltwater as part of the circuit. Students investigate the conductivity of saltwater, and develop an understanding of how the amount of salt in a solution impacts how much electrical current flows through the circuit. They learn about one real-world application of a saltwater circuit â as a desalination plant tool to test for the removal of salt from ocean water.

Integrated Teaching And Learning Program

452

Computer-aided modeling of a rectified DC load-permanent magnet generator system with multiple damper windings in the natural abc frame of reference  

Microsoft Academic Search

A computer-aided modeling method, used to analyze and predict the dynamic performance of electronically rectified load-permanent magnet generator systems, is presented. These generators include multiple damping circuits. Continuous electronic switching in such systems results in a continuous change in the machine system network topologies. Hence, network modeling of such systems is done on an instantaneous basis. The natural abc frame

A. A. Arkadan; T. M. Hijazi; N. A. Demerdash

1989-01-01

453

A novel approach to predict the pin load distribution of multiple bolt-jointed composite laminate based on the circuit model  

NASA Astrophysics Data System (ADS)

The circuit model was applied to predict the pin load distribution of composite multiple bolt-joint structure. The load, flexibility and deformation of the mechanics model were equivalent to the current, resistance and voltage of the circuit model, respectively. Based on the above assumption, it could be found that the Hooke's law and the deformation compatibility equation in the origin mechanics model transformed into the Ohm's law and the voltage balance equation in the new circuit model. This approach translated the complex model of composite multiple bolt-jointed into a simple circuit model which consisted of some series circuits and parallel circuits. The analysis of the new circuit model had formed n-1 independence voltage balance equations and a current balance equation, thus, the current and load of each bolt could be calculated. In the new model, power sources which were added as required in some branch circuits could also simulate the clearance or interference in the origin model. Compared with the result of the multiple bolt-joints composite laminate test, the new approach could make an excellent performance to estimate the load distribution.

Yang, Xiankun; Chen, Haoyuan; Cheng, Linan; Zheng, Xitao

2011-11-01

454

Observation and Modeling of Mars Crustal Magnetism  

NASA Astrophysics Data System (ADS)

Mars Global Surveyor's (MGS) magnetometer/electron reflectometer (MAG/ER) investigation mapped regions of intensely magnetized crust on Mars. The most intense crustal fields were observed over the ancient southern highlands but significant fields were observed over most of the planet. The most accurate magnetic field maps were compiled using data acquired during MGS mapping orbit at approximately 400 km altitude, owing to the large number of available observations and nearly complete global coverage. Interpretation of these maps yields valuable insight regarding crustal evolution on Mars, the role of plate tectonics, and a history of resurfacing by massive lava flows. However, one often desires knowledge of the field elsewhere - particularly nearer to the surface, directly sampled via aerobraking passes during pre-mapping (to 90 km altitude). The challenge is to find an appropriate technique for continuation of the vector magnetic field to lower altitudes. Methods used to infer magnetic fields include direct inversion (source modeling), Fourier techniques for downward continuation (as applied to survey data) and spherical harmonic modeling applied to global observations. We will discuss the pros and cons of each and present some promising results using an iterative Fourier technique for downward continuation.

Connerney, J. E.; Espley, J.; Acuna, M.

2009-05-01

455

A novel finite element method for the modeling of multiple reflections in photonic integrated circuits  

NASA Astrophysics Data System (ADS)

The complex transverse waveguide geometries of integrated photonic devices warrant the application of intricate Numerical Methods when modelling these types of Planar Lightwave Circuits (PLC). To aggravate the problem, difficulties also arise when dealing with back-reflections at interfaces, counter-propagating signals and other associated losses. Routines such as the Finite Element Method (FEM) and Finite Difference Method (FDM) are utilised in simulating the propagation of light through the core waveguide structures of these PLCs. In this paper a novel FEM reliant upon device cross-sectional symmetry is proposed, developed and discussed in regards to its advantages in precision over other procedures. Upon completion of this analysis, the propagation constant and effective refractive indices are known and extensions may be employed to accurately model propagation through the device and outline any reflections or losses that may ensue. A clear and concise review of some of the foremost available schemes is also presented here. These techniques, such as the Bidirectional Eigenmode Propagation Method (BEP) and the Beam Propagation Method (BPM) will be discussed and an effective and precise 3-dimensional model is presented. Due to the myriad of available techniques and algorithms, a comparative study is drawn, listing the advantages and failures of the major methods while suggesting improvements to their application. Necessary considerations such as simulation time and the trade-off between computer memory requirements and accuracy of the solution are also acknowledged.

Ging, John A.; O'Dowd, Ronan

2006-05-01

456

Modeling of magnetic field driven simultaneous assembly  

NASA Astrophysics Data System (ADS)

The Magnetic Field Driven Simultaneous Assembly (MFDSA) is a method that offers a non-statistical and deterministic solution to the problem of assembly via batch processing; a hybrid of serial and parallel processing. The technique requires the use of electromagnets as well as soft and hard magnetic materials that are applied to devices and recesses respectively. The MFDSA approach offers the ability to check and correct errors in real-time and is capable of scalable, versatile, and high-yield integration. Devices, coated with a layer of soft magnetic material, are moved from initial to final positions along predetermined pathways through the action of an array of electromagnets. Various devices, of arbitrary geometries, with different physical and functional properties, are manipulated simultaneously toward specific desired locations and then dropped onto a template under the influence of gravity by weakening the local applied field. Locations on the template correspond to sites on a substrate that contain recesses. When a number of devices have been dropped onto the template, a substrate is pressed onto it and the soft magnetic layers on the devices adhere to the hard magnetic strips in the recesses, completing integration in a single step. The objectives of this dissertation are the following: to present the MFDSA method; comparing and contrasting it with other extant techniques employed by the semiconductor industry; to discuss key aspects of this solution with respect to the problem of assembly, and to model the calculations involved with determining both device pathways and field interactions that are required to implement the approach. The Fourier Series technique will be used to describe the force of attraction between the device's soft magnetic layer and the recess's hard magnetic strips. Methodology from finite element analysis will be employed to calculate the force exerted on a device by an array of electromagnets. The Swarm Algorithm, which was developed in this work to calculate device pathways, will be presented as a stable, well-defined solution. Other concepts, such as the magnetic retention factor and the collision cross-section area, will be presented and developed. The solution to the problem of assembly, via the Swarm Algorithm, will be compared and contrasted with other analogous problems found in the literature. The results of these models, including software implementation, will be presented.

Rivero, Rene David

457

The Switching Severity of Industrial Circuits -I  

Microsoft Academic Search

Circuit power factor has long been used as a rough measure of circuit interrupting severity. Closer analysis reveals that with some types of modern circuit interrupters (fuses, magnetic air breakers, load break switches) new definitions must be sought to describe the true severity of the application and test circuits. This paper presents the nature of the problem to be solved.

E. W. Boehne

1963-01-01

458

Exploring the low-frequency performance of thermal converters using circuit models and a digitally synthesized source  

Microsoft Academic Search

Low-frequency errors of thermal voltage converters are described and estimated using a circuit model that includes easily measured parameters. A digitally synthesized source is used to confirm the estimated ac-dc differences in the 0.01 Hz to 40 Hz range

Nile M. Oldham; Svetlana Avramov-Zamurovic; Mark E. Parker

1997-01-01

459

Application of Workflow Petri Nets to Modeling of Formal Verification Processes in Design Flow of Digital Integrated Circuits  

Microsoft Academic Search

According to statistics the verification of digital integrated circuits (IC) claims up to 70 % of the design time and effort in the design process. This means that the verification process must be well structured and organized in order to efficiently reach desired verification goals. This paper describes the modelling of an exhaustive formal verification process of a digital IC

Katharina Weinberger; Slava Bulach; Robert Bosch

2008-01-01

460

Comparison of a CFD Analysis and a Thermal Equivalent Circuit Model of a TEFC Induction Machine With Measurements  

Microsoft Academic Search

For a totally enclosed fan-cooled induction machine, two methods of numerical analysis are compared with measurements. The first numerical method is based on computational fluid dynamics (CFDs) and the second one uses a thermal equivalent circuit (TEC). For the analysis based on CFD, a 3-D induction machine including housing is modeled. The numeric solution of the flow equations is determined

Christian Kral; Anton Haumer; Matthias Haigis; Hermann Lang; HansjÖrg Kapeller

2009-01-01

461

Study of the sudden symmetrical short-circuit using the mathematical models of the synchronous machine and the numerical methods  

Microsoft Academic Search

In the last decade, the field of Fault Detection and Diagnosis in the electric motor manufacturing industry, are becoming more important. The methods used to study the fault detection and diagnoses are based on an explicit mathematical model of the system under test. This article presents, in detail, a method for the study and the simulation of a symmetrical short-circuit

G. P. Serb; I. P. Serb; Campeanu Aurel; Sonia Degeratu; Anca Petrisor

2008-01-01

462

Analytical (“mathematical”) modeling of the dynamic response of a printed circuit board (PCB) to an impact load  

Microsoft Academic Search

Based on the developed analytical (“mathematical”) stress model, we evaluate the dynamic response of a “flexible-and-heavy” square simply supported printed circuit board (PCB) to an impact load applied to its support contour during drop tests. The analysis is restricted to the first mode of vibrations and is carried out in application to a PCB structure employed in an advanced accelerated

E. Suhir

2010-01-01

463

A Model for the Failure of Bipolar Silicon Integrated Circuits Subjected to Electrostatic Discharge  

Microsoft Academic Search

The results are presented of a study into the mechanism by which failure occurs in an integrated circuit when it is subjected to a discharge of static electricity. The current that flows through an integrated circuit during a static discharge is shown to be an exponentially decaying current pulse. The peak value and rate of decay of the pulse can

Thomas S. Speakman

1974-01-01

464

Quantum-Dot Cellular Automata (QCA) circuit partitioning: problem modeling and solutions  

Microsoft Academic Search

This paper presents the Quantum-Dot Cellular Automata (QCA) physical design problem, in the context of the VLSI physical design problem. The problem is divided into three subproblems: partitioning, placement, and routing of QCA circuits. This paper presents an ILP formulation and heuristic solution to the partitioning problem, and compares the two sets of results. Additionally, we compare a human-generated circuit

Dominic A. Antonelli; Danny Z. Chen; Timothy J. Dysart; Xiaobo Sharon Hu; Andrew B. KahngPeter; Peter M. Kogge; Richard C. Murphy; Michael T. Niemier

2004-01-01

465

Modelling discharge lamps for electronic circuit designers: a review of the existing methods  

Microsoft Academic Search

Summary form only given. The purpose of this paper is that to present a concise review of the methods used up to now for the description of electrical discharge lamps a part of an electronic circuit. Several attempts to describe the lamp by an equivalent electric circuit have been made with more or less accurate results. Some attempts to integrate

G. Zissis; J. J. Damelincourt

2002-01-01

466

Model-based reasoning for electron-beam debugging of VLSI circuits  

Microsoft Academic Search

This article deals with prototype validation of VLSI circuits. Circuits are observed using electron-beam probing used in voltage contrast mode, in such a way that grey level images are obtained and processed in order to determine potential values of connexions. These values are compared against reference values, issued from fault-free simulation of the device under test. The list of discrepancies

Meryem Marzouki

1991-01-01

467

Can Environmental Magnetism Set Constraints on Rock Magnetic Models? An Example Based on Soils  

NASA Astrophysics Data System (ADS)

Rock magnetic models are needed to understand the occurrence of magnetic minerals in rocks and sediments, and their relationship with geology, biology, and climate. Since the foundation of rock magnetism by Louis Neel, rock magnetic models have been validated mainly on synthetic assemblages of magnetic crystals of known composition, size, and shape. However, the magnetic properties of a natural assemblage of magnetic grains depend as well on a many secondary parameters, such as the occurrence of crystal defects, oxidation gradients, surface effects, and magnetostatic interactions. It is extremely difficult to include these parameters in rock magnetic models, and even if possible, such models have to deal with the unknown statistical distribution of all parameters under consideration. Hence, the exact magnetic properties of natural grain assemblages can be determined only empirically using magnetic unmixing methods. An assemblage of particles with a common geologic and biogeochemical history - hereafter called magnetic component - is characterized by a statistical distribution of physical and chemical properties that depends on the mechanisms of formation and alteration of the particles. The statistical distribution of the parameters related to a specific magnetic component (e.g. pedogenic magnetite, magnetosomes) is expected to show a systematicity that is reflected in the magnetic measurements (magnetic signature). The empirically determined magnetic signature of a natural component is a better reference than synthetic samples for the validation of rock magnetic models. The comparison of the magnetic signature of natural components with current models allows to determine which parameters have to be taken into consideration and which parameters can be neglected. For example: is the Stoner-Wohlfarth model sufficient to model a pedogenic component? Should multiple easy axes and surface effects be taken into account? The case of rock magnetic models applied to low-coercivity pedogenic components is discussed as an example.

Egli, R.

2005-12-01

468

Mutual coupling between short-circuited microstrip antennas  

NASA Astrophysics Data System (ADS)

A method has been previously developed for the computations of mutual coupling between the usual rectangular printed antennas. In the letter the short-circuited antennas with three magnetic walls and an electric wall are investigated. Using the cavity model with hybrid boundary conditions (magnetic wall and electric wall) and the equivalence theorem, the problem is reduced to the interactions of two U-shaped magnetic currents. Theory and experiment are in very good agreement.

Penard, E.; Daniel, J.-P.

1983-03-01

469

New Method to Model the Equivalent Circuit of the Pulse Generator in Electrical Fast Transient/Burst Test  

NASA Astrophysics Data System (ADS)

This paper presents an accurate and systematic method to model the equivalent circuit of pulse generator in the electrical fast transients/burst test (EFT/B). Firstly, a new analytical expression is presented to express the generator's charging and discharging process under open-condition (1000-?), which all its coefficients are determined according to the output waveform specified by the manufacturer. And then, with adoption of the step source, the transfer function of the pulse forming network in Laplace domain is deduced, which is ready for the network synthesis. Based on above discussion, the parameterized method and the technique of constant-resistance are adopted for the network synthesis. Finally, the equivalent circuit is renormalized and improved to meet the specification under matching-condition (50-?). In this way, the equivalent circuit of EFT/B generator is obtained and can be adjusted conveniently to satisfy the different manufacturers. The PSPICE simulation with a certain load is validated by measurement.

Zhai, Xiaoshe; Geng, Yingsan; Wang, Jianhua; Song, Zhengxiang; Chen, Degui

470

Massive Modes in Magnetized Brane Models  

NASA Astrophysics Data System (ADS)

We study higher dimensional models with magnetic fluxes, which can be derived from superstring theory. We study mass spectrum and wavefunctions of massless and massive modes for spinor, scalar and vector fields. We compute the 3-point couplings and higher order couplings among massless modes and massive modes in 4D low-energy effective field theory. These couplings have non-trivial behaviors, because wavefunctions of massless and massive modes are non-trivial.

Hamada, Y.; Kobayashi, T.

2012-11-01

471

Proactive inhibitory control and attractor dynamics in countermanding action: a spiking neural circuit model  

PubMed Central

Flexible behavior depends on the brain’s ability to suppress a habitual response or to cancel a planned movement whenever needed. Such inhibitory control has been studied using the countermanding paradigm in which subjects are required to withhold an imminent movement when a stop signal appears infrequently in a fraction of trials. To elucidate the circuit mechanism of inhibitory control of action, we developed a recurrent network model consisting of spiking movement (GO) neurons and fixation (STOP) neurons, based on neurophysiological observations in the frontal eye field and superior colliculus of behaving monkeys. The model places a premium on the network dynamics prior to the onset of a stop signal, especially the experimentally observed high baseline activity of fixation neurons, which is assumed to be modulated by a persistent top-down control, and their synaptic interaction with movement neurons. The model simulated observed neural activity and fit behavioral performance quantitatively. In contrast to a race model in which the stop process is initiated at the onset of a stop signal, in our model whether a movement will eventually be canceled is determined largely by the proactive top-down control and the stochastic network dynamics even before the appearance of the stop signal. A prediction about the correlation between the fixation neural activity and the behavioral outcome was verified in the neurophysiological data recorded from behaving monkeys. The proposed mechanism for adjusting control through tonically active neurons that inhibit movement-producing neurons has significant implications for exploring the basis of impulsivity associated with psychiatric disorders.

Lo, Chung-Chuan; Boucher, Leanne; Pare, Martin; Schall, Jeffrey D.; Wang, Xiao-Jing

2009-01-01

472

Extraction of a lumped element, equivalent circuit model for via interconnections in 3-D packages using a single via structure with embedded capacitors  

Microsoft Academic Search

A methodology for extracting an accurate, lumped element, equivalent circuit model for an interlayer via in a 3-D packaging scheme is presented. The model of a single via is extracted based upon the EM simulation of a test structure in which the via is landed at an internal capacitance layer within the multi-layer Liquid Crystal Polymer (LCP) or Printed Circuit

Chung Hang John Poh; Swapan K. Bhattacharya; Jason Ferguson; John D. Cressler; John Papapolymerou

2010-01-01

473

Investigation of the interfaces in schottky diodes using equivalent circuit models.  

PubMed

The metal-semiconductor contact is one of the most critical factors that determine the performance of semiconductor devices such as Schottky barrier diodes (SBDs). SBDs between conductive carbon thin films and silicon have attracted attention due to their high performance and potential low cost of fabrication. Here, we introduce impedance spectroscopy (IS) as a powerful technique to characterize such SBDs. The electrical and structural characteristics of carbon-silicon SBDs between silicon and two different types of conductive carbon thin films have been investigated. Modeling the data with an extended equivalent circuit model reveals the effects of the metal electrode contacts of SBDs for the first time. From dc current-voltage measurements, diode parameters including the ideality factor, the Schottky barrier height, and the series resistance are extracted. Through use of analysis with IS, additional information on the Schottky contact is obtained, such as the built-in potential and more reliable barrier height values. Thus, IS can be utilized to analyze interfaces between metals and semiconductors in great detail by electrical means. PMID:23767937

Yim, Chanyoung; McEvoy, Niall; Kim, Hye-Young; Rezvani, Ehsan; Duesberg, Georg S

2013-07-12

474

A network flow model for load balancing in circuit-switched multicomputers  

SciTech Connect

In multicomputers that utilize circuit switching or wormhole routing, communication overhead depends largely on link contention - the variation due to distance between nodes is negligible. This has a major impact on the load balancing problem. In this case, there are some nodes with excess load (sources) and others with deficit load (sinks) and it is required to find a matching of sources to sinks that avoids contention. The problem is made complex by the hardwired routing on currently available machines: the user can control only which nodes communicate but not how the messages are routed. Network flow models of message flow in the mesh and the hypercube were developed to solve this problem. The crucial property of these models is the correspondence between minimum cost flows and correctly routed messages. To solve a given load balancing problem, a minimum cost flow algorithm is applied to the network. This permits one to determine efficiently a maximum contention free matching of sources to sinks which, in turn, tells one how much of the given imbalance can be eliminated without contention. 21 refs.

Bokhari, S.H. (Univ. of Engineering and Technology, Lahore (Pakistan))

1993-06-01

475

Modeling geometric frustration with magnetic colloids  

NASA Astrophysics Data System (ADS)

The implementation of artificial frustrated spin systems can give insight into the mechanisms which lead to the different equilibrium configurations in geometrically frustrated magnetic materials. Prominent artificial systems are the patterns of superconducting rings or nanometer-sized ferromagnetic islands. These are Ising systems allowing two possible in-plane orientations for each macroscopic moment. Here we present an alternative method using magnetically interacting colloids. The spherical shape of the particles allows the modeling of spin systems with continuous symmetry. Micrometer-sized silica particles are half capped with a Co/Pd multilayer thin film. Such thin films on curved surfaces have a predefined net magnetic moment called macrospin. The interaction of such particles in the self-arranged close-packed 2D structure is frustrated. Using video microscopy, the direction of the individual macrospins can be visualized by the spatial orientation of the magnetic caps. This setup allows us to investigate geometric frustration in static systems and in dynamic processes, e.g. during the particle-wise cluster growth. Further, we evaluate the impact of intrinsic defects and control defect formation extrinsically e.g. by varying the growth conditions.

Steinbach, Gabi; Gemming, Sibylle; Erbe, Artur; Nissen, Dennis; Albrecht, Manfred

2013-03-01

476

Fluid model for relativistic, magnetized plasmas  

SciTech Connect

Many astrophysical plasmas and some laboratory plasmas are relativistic: Either the thermal speed or the local bulk flow in some frame approaches the speed of light. Often, such plasmas are magnetized in the sense that the Larmor radius is smaller than any gradient scale length of interest. Conventionally, relativistic magnetohydrodynamics (MHD) is employed to treat relativistic, magnetized plasmas. However, MHD requires the collision time to be shorter than any other time scale in the system. Thus, MHD employs the thermodynamic equilibrium form of the stress tensor, neglecting pressure anisotropy and heat flow parallel to the magnetic field. Recent work has attempted to remedy these shortcomings. This paper re-examines the closure question and finds a more complete theory, which yields a more physical and self-consistent closure. Beginning with exact moments of the kinetic equation, we derive a closed set of Lorentz-covariant fluid equations for a magnetized plasma allowing for pressure and heat flow anisotropy. Basic predictions of the model, especially of the dispersion relation's dependence upon relativistic temperature, are examined.

TenBarge, J. M.; Hazeltine, R. D.; Mahajan, S. M. [Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712 (United States)

2008-06-15

477

Totally self-checking circuits and testable CMOS circuits  

Microsoft Academic Search

A Totally Self-Checking (TSC) circuit belongs to a class of circuits used for Concurrent Error Detection (CED) purposes. It consists of a functional circuit that has encoded inputs and outputs and a checker that monitors these outputs and gives and error indication. It is known that the traditional stuck-at fault model is not sufficient to model realistic physical failures. Techniques

N. K. Jha

1986-01-01

478

Hot-carrier induced series resistance enhancement model (HISREM) of nMOSFET's for circuit simulations and reliability projections  

Microsoft Academic Search

This paper proposes a physically realizable reliability model of nMOSFET's that is applicable for reliability projections in IC design. We have devised a hot-carrier induced series (drain) resistance enhancement model (HISREM) which is based on the increase of the interface trapped charge (?Nit) near the drain region and is physically realizable in circuit simulations of the hot-carrier induced degradation under

Nam Hwang; Leonard Forbes

1995-01-01

479

Neural-network-based parasitic modeling and extraction verification for RF\\/millimeter-wave integrated circuit design  

Microsoft Academic Search

This paper reports an interconnect modeling approach for RF and millimeter-wave integrated circuits (ICs) using neural network models and a novel parasitic extraction verification procedure using automatically generated test structures. The effects of the parasitics in RF\\/millimeter-wave ICs are investigated with special focus on the parasitic inductances, since they are not evaluated by most of the commercially available extraction tools.

Padmanava Sen; Wayne H. Woods; Saikat Sarkar; Rana J. Pratap; Brian M. Dufrene; Rajarshi Mukhopadhyay; Chang-Ho Lee; Essam F. Mina; Joy Laskar

2006-01-01

480

A nonlinear GaAs FET model for use in the design of output circuits for power amplifiers  

Microsoft Academic Search

A nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, inducing drain-gate avalanche current data. The harmonic-balance technique is used to develop the FET load-pull characteristics in an amplifier configuration under large-signal operation. Computed and experimental load-pull results show good agreement.

W. R. Curtice; M. Ettenberg

1985-01-01

481

Model for estimating radiated emissions from a printed circuit board with attached cables due to Voltage-driven sources  

Microsoft Academic Search

Common-mode currents induced on cables attached to printed circuit boards (PCBs) can be a significant source of unintentional radiated emissions. This paper develops a model for estimating the amount of common-mode cable current that can be induced by the signal voltage on microstrip trace structures or heatsinks on a PCB. The model employs static electric field solvers or closed-form expressions

Hwan-Woo Shim; T. H. Hubing

2005-01-01

482

Physics-based large-signal sensitivity analysis of microwave circuits using technological parametric sensitivity from multidimensional semiconductor device models  

Microsoft Academic Search

The authors present an efficient approach to evaluate the large-signal (LS) parametric sensitivity of active semiconductor devices under quasi-periodic operation through accurate, multidimensional physics-based models. The proposed technique exploits efficient intermediate mathematical models to perform the link between physics-based analysis and circuit-oriented simulations, and only requires the evaluation of dc and ac small-signal (dc charge) sensitivities under general quasi-static conditions.

Fabrizio Bonani; Simona Donati Guerrieri; Fabio Filicori; Giovanni Ghione; Marco Pirola

1997-01-01

483

Stellar magnetic fields: observations and nonlinear modeling  

NASA Astrophysics Data System (ADS)

Magnetic fields on a global scale are observed in a wide variety of astrophysical objects, spanning from planets, stars, and accretion disks to galaxies. These magnetic fields are anything but passive, taking part in the dynamics of their hosts, resulting for example in the familiar activity phenomena of the Sun, which also affect life here on the Earth. We have a long time series of temperature mapping and photometry of an active late-type star II Peg. II Peg is known as one of the most active RS Cvn stars representing the Sun at a younger age. We are trying to establish the link between the Sun and the more active rapidly rotating stars and compare the results to the dynamo models of the Sun. Preliminary results show some resemblance to the dynamo solutions.

Lindborg, M.; Korpi, M.; Tuominen, I.; Hackman, T.; Ilyin, I.; Käpylä, P.

2009-12-01

484

A study on the maximum power transfer condition in an inductively coupled plasma using transformer circuit model  

NASA Astrophysics Data System (ADS)

Correlations between the external discharge parameters (the driving frequency ? and the chamber dimension R) and plasma characteristics (the skin depth ? and the electron-neutral collision frequency ?m) are studied using the transformer circuit model [R. B. Piejak et al., Plasma Sources Sci. Technol. 1, 179 (1992)] when the absorbed power is maximized in an inductively coupled plasma. From the analysis of the transformer circuit model, the maximum power transfer conditions, which depend on the external discharge parameters and the internal plasma characteristics, were obtained. It was found that a maximum power transfer occurs when ?~0.38R for the discharge condition at which ?m/?<<1, while it occurs when ?~2?/?mR for the discharge condition at which ?m/?>>1. The results of this circuit analysis are consistent with the stable last inductive mode region of an inductive-to-capacitive mode transition [Lee and Chung, Phys. Plasmas 13, 063510 (2006)], which was theoretically derived from Maxwell's equations. Our results were also in agreement with the experimental results. From this work, we demonstrate that a simple circuit analysis can be applied to explain complex physical phenomena to a certain extent.

Kim, Young-Do; Lee, Hyo-Chang; Chung, Chin-Wook

2013-09-01

485

Multiple frequency bioelectrical impedance analysis: a cross-validation study of the inductor circuit and Cole models.  

PubMed

It has been proposed that multiple frequency bioelectrical impedance models of the human body should include an inductive property for the circulatory system, the inductor circuit model (ICM), and that such a model, when coupled with a new method of data analysis, can improve the predictive power of multiple frequency bioelectrical impedance analysis (MFBIA). This hypothesis was tested using MFBIA measurements and gold standard measures of total body and extracellular water volumes in a cross-validation study in two subject groups (viz. controls and HIV). The MFBIA measurements were analysed using the current, widely accepted Cole model and the alternative ICM model which includes an inductive component. Correlations in the range 0.75 to 0.92 (for TBW) and 0.46 to 0.79 (for ECW) for impedance quotients versus gold standard measures within the subject groups were observed. These decreased, to as low as r = 0.50 for TBW and r = 0.29 for ECW, when the derived algorithms were applied to the alternative subject group. These results suggest that lack of portability of MFBIA algorithms between subject groups is not due to an inadequacy of the analogue circuit model per se but is possibly due more to fundamental flaws in the principles associated with its application. These include assuming a constant proportionality of body segment geometries and tissue fluid resistivities. This study has also demonstrated that this inadequacy cannot be overcome by simply introducing an inductive component into the analogue electrical circuit. PMID:10593227

Ward, L; Cornish, B H; Paton, N I; Thomas, B J

1999-11-01

486

Circuit properties generating gamma oscillations in a network model of the olfactory bulb.  

PubMed

The study of the neural basis of olfaction is important both for understanding the sense of smell and for understanding the mechanisms of neural computation. In the olfactory bulb (OB), the spatial patterning of both sensory inputs and synaptic interactions is crucial for processing odor information, although this patterning alone is not sufficient. Recent studies have suggested that representations of odor may already be distributed and dynamic in the first olfactory relay. The growing evidence demonstrating a functional role for the temporal structure of bulbar neuronal activity supports this assumption. However, the detailed mechanisms underlying this temporal structure have never been thoroughly studied. Our study focused on gamma (40-100 Hz) network oscillations in the mammalian OB, which is a f