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1

Electrodynamic finite element model coupled to a magnetic equivalent circuit  

NASA Astrophysics Data System (ADS)

An electrodynamic field is coupled to a magnetic equivalent circuit. The electrodynamic problem is formulated by the electric vector potential and discretised by finite elements. The magnetic lumped parameter model is described in terms of unknown fluxes and magnetomotive forces. The coupled system matrix has a mixed and hybrid nature. In this presentation, the method is applied to simulate eddy current distributions in laminated material and losses in a dielectric heater.

de Gersem, H.; Hameyer, K.

2000-11-01

2

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

3

An Integrated Magnetic Circuit Model and Finite Element Model Approach to Magnetic Bearing Design  

NASA Technical Reports Server (NTRS)

A code for designing magnetic bearings is described. The code generates curves from magnetic circuit equations relating important bearing performance parameters. Bearing parameters selected from the curves by a designer to meet the requirements of a particular application are input directly by the code into a three-dimensional finite element analysis preprocessor. This means that a three-dimensional computer model of the bearing being developed is immediately available for viewing. The finite element model solution can be used to show areas of magnetic saturation and make more accurate predictions of the bearing load capacity, current stiffness, position stiffness, and inductance than the magnetic circuit equations did at the start of the design process. In summary, the code combines one-dimensional and three-dimensional modeling methods for designing magnetic bearings.

Provenza, Andrew J.; Kenny, Andrew; Palazzolo, Alan B.

2003-01-01

4

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

5

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

6

Magnetic Circuit Model of PM Motor-Generator to Predict Radial Forces  

NASA Technical Reports Server (NTRS)

A magnetic circuit model is developed for a PM motor for flywheel applications. A sample motor is designed and modeled. Motor configuration and selection of materials is discussed, and the choice of winding configuration is described. A magnetic circuit model is described, which includes the stator back iron, rotor yoke, permanent magnets, air gaps and the stator teeth. Iterative solution of this model yields flux linkages, back EMF, torque, power, and radial force at the rotor caused by eccentricity. Calculated radial forces are then used to determine motor negative stiffness.

McLallin, Kerry (Technical Monitor); Kascak, Peter E.; Dever, Timothy P.; Jansen, Ralph H.

2004-01-01

7

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

8

Circuits and Magnetic Fields  

NSDL National Science Digital Library

In this activity, students use the same method as in the activity from lesson 2 to explore the magnetism due to electric current instead of a permanent magnet. Students use a compass and circuit to trace the magnetic field lines induced by the electric current moving through the wire. Students develop an understanding of the effect of the electrical current on the compass needle through the induced magnetic field and understand the complexity of a three dimensional field system.

Vu Bioengineering Ret Program

9

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

10

Analysis of electromagnetic performance of flux-switching permanent-magnet Machines by nonlinear adaptive lumped parameter magnetic circuit model  

Microsoft Academic Search

A nonlinear adaptive lumped parameter magnetic circuit model is developed to predict the electromagnetic performance of a flux-switching permanent-magnet machine. It enables the air-gap field distribution, the back-electromotive force (back-EMF) waveform, the winding inductances, and the electromagnetic torque to be calculated. Results from the model are compared with finite-element predictions and validated experimentally. The influence of end effects is also

Z. Q. Zhu; Y. Pang; D. Howe; S. Iwasaki; R. Deodhar; A. Pride

2005-01-01

11

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

12

Linear AC magnetic circuit theory  

Microsoft Academic Search

A theory is presented for linear, AC magnetic circuits. The theory develops real and imaginary reluctance terms, which are used in the same manner as real and imaginary impedance terms in linear, AC electrical circuit theory. The reluctance terms can be manipulated through coil-coupled resistances and capacitances. The theory is applied to a parallel magnetic-circuit configuration to show the limits

Otto Henry Zinke; William F. Schmidt

1993-01-01

13

Electrically detected magnetic resonance modeling and fitting: An equivalent circuit approach  

NASA Astrophysics Data System (ADS)

The physics of electrically detected magnetic resonance (EDMR) quadrature spectra is investigated. An equivalent circuit model is proposed in order to retrieve crucial information in a variety of different situations. This model allows the discrimination and determination of spectroscopic parameters associated to distinct resonant spin lines responsible for the total signal. The model considers not just the electrical response of the sample but also features of the measuring circuit and their influence on the resulting spectral lines. As a consequence, from our model, it is possible to separate different regimes, which depend basically on the modulation frequency and the RC constant of the circuit. In what is called the high frequency regime, it is shown that the sign of the signal can be determined. Recent EDMR spectra from Alq3 based organic light emitting diodes, as well as from a-Si:H reported in the literature, were successfully fitted by the model. Accurate values of g-factor and linewidth of the resonant lines were obtained.

Leite, D. M. G.; Batagin-Neto, A.; Nunes-Neto, O.; Gómez, J. A.; Graeff, C. F. O.

2014-01-01

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, D.G.; Birx, D.; Cook, E.G.

1993-01-05

15

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

16

Incorporating the Effects of Magnetic Saturation in a Coupled-Circuit Model of a Claw–Pole Alternator  

Microsoft Academic Search

A method of representing the effects of magnetic saturation in a coupled-circuit model of a claw-pole alternator is presented. In the approach considered, the airgap flux density produced by each winding is expressed as a function of magnetic operating point. A challenge in the implementation is that the airgap flux densities consist of several significant harmonics, each of which changes

Hua Bai; Steven D. Pekarek; Jerry Tichenor; Walter Eversman; Duane J. Buening; Gregory R. Holbrook; Ronald J. Krefta

2007-01-01

17

Computer simulation of magnetic switching circuits and magnetic energy losses  

Microsoft Academic Search

A computer simulation has been developed to model the actions of magnetic switching circuits. Simulations are compared to experimental data obtained from a one-stage magnetically switched circuit. Comparisons between experimental and computed switch voltage and current waveforms are made for various operating conditions, pre-saturation leakage currents, and for energy losses. The computer simulation models the actual core saturation process, including

Rhinehart; H. E. Jr

1989-01-01

18

Identification and simulation of a circuit-based model of magnetic hysteresis  

Microsoft Academic Search

Purpose – The scope of the work is to provide an identification procedure for an hysteresis model based on nonlinear circuit cells. Design\\/methodology\\/approach – An identification procedure for an hysteresis model based on nonlinear circuit cells is presented. The response of elementary cell is equal to a generalized play operator. The procedure allows the identification of the limit symmetric hysteresis

G. Gruosso; M. Repetto

2005-01-01

19

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

20

Verification by finite element modeling offor the originorigin of the apparent image effect in closed-circuit magnetic measurements  

NASA Astrophysics Data System (ADS)

Closed-circuit magnetic measurements using a hysteresisgraph have generally been considered free from errors associated with the demagnetizing factor, as well as from the image effect, both of which can occur in open-circuit measurements. However, measurements on magnetic samples clamped between the pole pieces of an electromagnet may show an apparent drop in magnetization with increasing applied field, similar to the image effect found in open-circuit measurements. We have shown that as the saturation magnetization of the sample increases, the drop in apparent magnetization becomes greater and appears at lower fields; the effect also increases as the length-to-diameter ratio L/ D of the sample decreases. This behavior has been attributed to distortion of the magnetic field distribution around the sample resulting from localized saturation of the electromagnet pole pieces. This paper presents the results of computer modeling using finite element method, FEM, which confirm this explanation and show that the field acting on the sample is highly non-uniform when the sample L/ D is small. The modeling results are in good agreement with experimental data, and show that the apparent drop in magnetization is caused by measurement of the applied field that does not accurately reflect the field acting on the sample.

Chen, C. H.; Graham, C. D.; Strnat, R. M.; Pugh, B. K.; Wangler, A.; Higgins, A. K.

2011-01-01

21

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

22

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

23

Analytical design of a high-torque flux-switching permanent magnet machine by a simplified lumped parameter magnetic circuit model  

Microsoft Academic Search

This paper presents how to analytically design a high-torque three-phase flux-switching permanent magnet machine with 12 stator poles and 14 rotor poles. Firstly, the machine design parameters are studied addressing on high output torque and its flux distribution is also investigated by finite-element method (FEM) analysis. Then a simplified lumped parameter magnetic circuit model is built up for analyzing design

Anyuan Chen; Robert Nilssen; Arne Nysveen

2010-01-01

24

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

25

Analysis and design of a coreless permanent-magnet machine considering the winding shape by using a lumped equivalent magnetic circuit model  

NASA Astrophysics Data System (ADS)

A simple and rapid analysis and design method is proposed for a coreless permanent magnet machine (CPMM) using a hexagonal winding (HW). The HW, which combines a rectangular winding (RTW) and rhombic winding (RBW), can compensate for the disadvantages and maximize the advantages of the RTW and RBW. The CPMM is typically analyzed using complex differential equations or a timeconsuming finite element analysis (FEA). To address this problem, a relatively simpler and less timeconsuming analysis method is proposed by using a lumped equivalent magnetic circuit (LEMC) model. Furthermore, an effect of winding angle on a motor performance is analyzed via precise inspection of the relationship between the variables of the HW and the characteristics of motor. The validity and usefulness of the proposed method are verified via FEA and experiment.

Seo, Jung-Moo; Jung, In-Soung; Jung, Hyun-Kyo; Ro, Jong-Suk

2014-05-01

26

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

1996-07-01

27

Control of flux in magnetic circuits for Barkhausen noise measurements  

Microsoft Academic Search

The consistency of magnetic Barkhausen noise (MBN) measurements under applied sinusoidal magnetic field control and sinusoidal magnetic circuit flux control was investigated under variable circuit permeability conditions. A U-core electromagnet was used to provide the alternating magnetic excitation. The magnetic circuit permeability was changed by varying excitation magnet lift-off and by using samples with known magnetic anisotropy. By controlling the

Steven White; Thomas Krause; Lynann Clapham

2007-01-01

28

Influence of rotor pole number on optimal parameters in flux-switching PM brushless AC machines by lumped parameter magnetic circuit model  

Microsoft Academic Search

The investigation on flux-switching permanent magnet (FSPM) machines in existing papers has been restricted to specific combination of stator and rotor pole numbers, viz. 12\\/10 stator\\/rotor poles. In this paper, the influence of stator and rotor pole numbers on the optimal parameters of the FSPM machines are investigated by the finite element analysis and the lumped parameter magnetic circuit model,

J. T. Chen; Z. Q. Zhu

2009-01-01

29

Influence of the Rotor Pole Number on Optimal Parameters in Flux-Switching PM Brushless AC Machines by the Lumped-Parameter Magnetic Circuit Model  

Microsoft Academic Search

The investigation on flux-switching permanent-magnet (FSPM) machines in existing papers has been restricted to a specific combination of stator and rotor pole numbers, viz., 12\\/10 stator\\/rotor poles. In this paper, the influence of stator and rotor pole numbers on the optimal parameters of the FSPM machines are investigated by the finite-element analysis and the lumped-parameter magnetic circuit model, respectively. It

J. T. Chen; Z. Q. Zhu

2010-01-01

30

Permanent Magnet Circuit Design Primer.  

National Technical Information Service (NTIS)

The advent of rare-earth permanent magnets (REPM) has brought the realization of novel magnetic structures that are not practicable otherwise. So different are these remarkable materials from the earlier magnets that conventional design wisdom is inadequa...

H. A. Leupold E. Potenziani

1996-01-01

31

Magnetic circuit for hall effect plasma accelerator  

NASA Technical Reports Server (NTRS)

A Hall effect plasma accelerator includes inner and outer electromagnets, circumferentially surrounding the inner electromagnet along a thruster centerline axis and separated therefrom, inner and outer magnetic conductors, in physical connection with their respective inner and outer electromagnets, with the inner magnetic conductor having a mostly circular shape and the outer magnetic conductor having a mostly annular shape, a discharge chamber, located between the inner and outer magnetic conductors, a magnetically conducting back plate, in magnetic contact with the inner and outer magnetic conductors, and a combined anode electrode/gaseous propellant distributor, located at a bottom portion of the discharge chamber. The inner and outer electromagnets, the inner and outer magnetic conductors and the magnetically conducting back plate form a magnetic circuit that produces a magnetic field that is largely axial and radially symmetric with respect to the thruster centerline.

Manzella, David H. (Inventor); Jacobson, David T. (Inventor); Jankovsky, Robert S. (Inventor); Hofer, Richard (Inventor); Peterson, Peter (Inventor)

2009-01-01

32

Static characteristics of linear BLDC motor using equivalent magnetic circuit and finite element method  

Microsoft Academic Search

This paper presents the static characteristics of the linear BLDC motor. An equivalent magnetic circuit model is derived for the prototype motor. The air-gap flux density is calculated using the equivalent magnetic circuit and compared with results from finite element analysis. The thrust force is measured for the prototype motor and is also compared with those from derived circuit model

J. K. Kim; S. W. Joo; S. C. Hahn; J. P. Hong; D. H. Kang; D. H. Koo

2004-01-01

33

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

34

Closed Circuit Television Model Program.  

ERIC Educational Resources Information Center

The resources of closed circuit television can improve teaching and learning in schools. Three junior high schools in Arlington Heights, Illinois have inaugurated a closed circuit television model program. The program's objectives are improvement of the quality of standard teacher-lesson presentations, redirection of teacher time and energy to…

Elms, Glen D.

35

Dynamical models of cortical circuits.  

PubMed

Cortical neurons operate within recurrent neuronal circuits. Dissecting their operation is key to understanding information processing in the cortex and requires transparent and adequate dynamical models of circuit function. Convergent evidence from experimental and theoretical studies indicates that strong feedback inhibition shapes the operating regime of cortical circuits. For circuits operating in inhibition-dominated regimes, mathematical and computational studies over the past several years achieved substantial advances in understanding response modulation and heterogeneity, emergent stimulus selectivity, inter-neuron correlations, and microstate dynamics. The latter indicate a surprisingly strong dependence of the collective circuit dynamics on the features of single neuron action potential generation. New approaches are needed to definitely characterize the cortical operating regime. PMID:24658059

Wolf, Fred; Engelken, Rainer; Puelma-Touzel, Maximilian; Weidinger, Juan Daniel Flórez; Neef, Andreas

2014-04-01

36

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

37

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

38

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

39

Power transformer design using magnetic circuit theory and finite element analysis — A comparison of techniques  

Microsoft Academic Search

This paper summarises a reverse method of transformer design where the construction details of the transformer are directly specified and are used to determine the device performance and ratings. Two magnetic models are presented for the inductive-reactance components of the Steinmetz 'exact' transformer equivalent circuit. The first model, based on magnetic circuit theory, is frequently taught in undergraduate power system

Simon C. Bell; Pat S. Bodger

2007-01-01

40

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous motor (PMHS). The hybrid synchronous motor consists of 36% cobalt steel hysteresis alloys with neodymium iron boron permanent magnets to improve the overall performances of such a motor. Based on the magnetic equivalent circuit, the control strategy of the PMHS motor is developed. Experimental results confirm the

R. Qin; M. A. Rahman

2003-01-01

41

VLSI circuits implementing computational models of neocortical circuits.  

PubMed

This paper overviews the design and implementation of three neuromorphic integrated circuits developed for the COLAMN ("Novel Computing Architecture for Cognitive Systems based on the Laminar Microcircuitry of the Neocortex") project. The circuits are implemented in a standard 0.35 ?m CMOS technology and include spiking and bursting neuron models, and synapses with short-term (facilitating/depressing) and long-term (STDP and dopamine-modulated STDP) dynamics. They enable execution of complex nonlinear models in accelerated-time, as compared with biology, and with low power consumption. The neural dynamics are implemented using analogue circuit techniques, with digital asynchronous event-based input and output. The circuits provide configurable hardware blocks that can be used to simulate a variety of neural networks. The paper presents experimental results obtained from the fabricated devices, and discusses the advantages and disadvantages of the analogue circuit approach to computational neural modelling. PMID:22342970

Wijekoon, Jayawan H B; Dudek, Piotr

2012-09-15

42

Plasma-circuit interactions in rotating magnetic field current drive  

Microsoft Academic Search

The interactions between the plasma and the radio frequency circuit in rotating magnetic field (RMF) current drive experiments are investigated numerically. A simplified 1D model for slowly varying conditions is used to study the penetration of the RMF into the plasma. The RMF is assumed to be generated using a two-phase two-coil arrangement and the effect of the spatial harmonics

W. N. Hugrass; T. Okada; M. Ohnishi

2008-01-01

43

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

44

TIMING MODELS FOR MOS CIRCUITS  

Microsoft Academic Search

Performance is an important aspect of integrated circuit design, and dependsin part on the speed of the underlying circuits. This thesis presents a new methodof analyzing MOS circuit delay, based on a single-time-constant approximation.

Mark Alan Horowitz

1984-01-01

45

Combined Electromagnetic and Circuit Approaches for Accurate RF Circuits Modeling  

Microsoft Academic Search

This paper discusses a methodology combining electromagnetic (EM) modelling and circuit analysis for optimisation of RF component performances. A modal-state formalism is considered to link electromagnetic field configurations (modal-states) with equivalent circuit model representations. Such link renders possible topology-driven design and synthesis where coupled analysis of dielectric\\/conductor losses and energy storage capabilities allows for optimised trade-off of low couplings and

T. Caillet; D. Bajon; S. Wane; R. Plana

2008-01-01

46

Magnetic resonance imaging of neural circuits  

Microsoft Academic Search

A major goal of modern MRI research is to be able to image neural circuits in the central nervous system. Critical to this mission is the ability to describe a number of important parameters associated with neural circuits. These parameters include neural architecture, functional activation of neural circuits, anatomical and functional connectivity of neural circuits, and factors that might alter

Alan P Koretsky; Jeff Duyn

2008-01-01

47

Biasing and fast degaussing circuit for magnetic materials  

DOEpatents

A dual-function circuit is provided which may be used to both magnetically bias and alternately, quickly degauss a magnetic device. The circuit may be magnetically coupled or directly connected electrically to a magnetic device, such as a magnetostrictive transducer, to magnetically bias the device by applying a d.c. current and alternately apply a selectively damped a.c. current to the device to degauss the device. The circuit is of particular value in many systems which use magnetostrictive transducers for ultrasonic transmission in different propagation modes over very short time periods.

Dress, Jr., William B. (Lenoir City, TN); McNeilly, David R. (Maryville, TN)

1984-01-01

48

Biasing and fast degaussing circuit for magnetic materials  

DOEpatents

A dual-function circuit is provided which may be used to both magnetically bias and alternately, quickly degauss a magnetic device. The circuit may be magnetically coupled or directly connected electrically to a magnetic device, such as a magnetostrictive transducer, to magnetically bias the device by applying a dc current and alternately apply a selectively damped ac current to the device to degauss the device. The circuit is of particular value in many systems which use magnetostrictive transducers for ultrasonic transmission in different propagation modes over very short time periods.

Dress, W.B. Jr.; McNeilly, D.R.

1983-10-04

49

Fast Analytical Determination of Aligned and Unaligned Flux Linkage in Switched Reluctance Motors Based on a Magnetic Circuit Model  

Microsoft Academic Search

Because a switched reluctance motor has inherently nonlinear magnetic characteristics and a doubly salient pole structure, a finite-element analysis approach (FEA) is often adopted to obtain accurate magnetic representation. However, the solution time can be large for a FEA simulation if the mesh is detailed and\\/or many simulations are required. We propose a rapid analytical solution for determining the aligned

Shang-Hsun Mao; David Dorrell; Mi-Ching Tsai

2009-01-01

50

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 are disclosed. 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. 17 figs.

Campbell, A.N.; Anderson, R.E.; Cole, E.I. Jr.

1995-11-07

51

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

52

System and Circuit Models for Microwave Antennas  

Microsoft Academic Search

This paper describes how circuit and system models are derived for antennas from measurement of the input reflection coefficient. Circuit models are used to optimize the antenna performance and to calculate the radiated power and the transfer function of the antenna. System models are then derived for transmitting and receiving antennas. The most important contribution of this study is to

Mohamed I. Sobhy; Benito Sanz-Izquierdo; John C. Batchelor

2007-01-01

53

Magnetic equivalent circuit of PM hysteresis synchronous motor  

Microsoft Academic Search

This paper presents the magnetic equivalent circuit of a permanent magnet hysteresis synchronous (PMHS) motor. The hybrid synchronous motor consists of 30% Cobalt-steel hysteresis alloys Neodymium Iron Boron (NdFeB) permanent magnets to improve the overall performances of motors.

Ruifeng Qin; M. A. Rahman

2003-01-01

54

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

55

Electrical circuit modeling of reversed field pinches  

NASA Astrophysics Data System (ADS)

Equations are proposed to describe the radial variation of the magnetic field and current density in a circular, cylindrical RFP. These equations are used to derive the electrical circuit parameters (inductance, resistance, and coupling coefficient) for an RFP discharge. The circuit parameters are used to evaluate the flux and energy consumption for various startup modes and for steady-state operation using oscillating field current drive. The results are applied to the MST device.

Sprott, J. C.

1988-02-01

56

Equivalent Circuit Modeling of Hysteresis Motors  

SciTech Connect

We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates, amenable to circuit or digital simulation. 'Hunting' is an oscillatory phenomenon often observed in hysteresis motors. While several works have attempted to model the phenomenon with some partial success, we present a new complete model that predicts hunting from first principles.

Nitao, J J; Scharlemann, E T; Kirkendall, B A

2009-08-31

57

Symbolic model checking for sequential circuit verification  

Microsoft Academic Search

The temporal logic model checking algorithm of Clarke, Emerson, and Sistla (17) is modified to represent state graphs using binary decision diagrams (BDD's) (7) and partitioned trunsirion relations (lo), 1111. Because this representation captures some of the regularity in the state space of circuits with data path logic, we are able to verify circuits with an extremely large number of

Jerry R. Burch; Edmund M. Clarke; David E. Long; Kenneth L. Mcmillan

1994-01-01

58

Sequential Circuit Verification Using Symbolic Model Checking  

Microsoft Academic Search

The temporal logic model checking algorithm devel- oped by Clarke, Emerson, and Sistla (9) is modified to represent a state graph using Binary decision diagrams (BDD's) (4). B ecause this representation captures some of the regularity in the state space of sequential circuits with data path logic, we are able to verify circuits with an extremely large number of states.

Jerry R. Burch; Edmund M. Clarke; Kenneth L. Mcmillan

1990-01-01

59

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

60

Terminal modeling of hardened integrated circuits  

NASA Astrophysics Data System (ADS)

Kleiner et al. (1979) have reported modeling and test verification techniques used to develop medium-scale, dielectrically isolated integrated circuits (DIIC). The current investigation is concerned with the approaches employed in modeling the new circuits for applications studied by design and radiation hardening engineers. The described technique improves significantly the cost-effective application of computer programs such as SYSCAP II. The terminal model offers the designer of radiation-hardened electronic circuits a method for evaluating the effects of radiation transients on single or multiple piece-part response at the circuit board level. Although the models presented were intended for TREE design and analysis, it is possible to extend the technique to EMP and SGEMP evaluations.

Kleiner, C. T.; Haas, R.; Peacock, M.; Mandel, G.; Messenger, G. C.; Weakley, D.; Demartino, V.

1981-12-01

61

Sequential circuit verification using symbolic model checking  

Microsoft Academic Search

The temporal logic model algorithm of E.M. Clarke et al. (ACM Trans. Prog. Lang. Syst., vol.8, no.2, p.244-63, 1986) is modified to represent a state graph using binary decision diagrams (BDDs). Because this representation captures some of the regularity in the state space of sequential circuits with data path logic, one is able to verify circuits with an extremely large

J. R. Burch; E. M. Clarke; K. L. McMillan; David L. Dill

1990-01-01

62

Equivalent Circuit Modeling of Hysteresis Motors.  

National Technical Information Service (NTIS)

We performed a literature review and found that many equivalent circuit models of hysteresis motors in use today are incorrect. The model by Miyairi and Kataoka (1965) is the correct one. We extended the model by transforming it to quadrature coordinates,...

B. A. Kirkendall E. T. Scharlemann J. J. Nitao

2009-01-01

63

Three-Dimensional Lumped-Parameter Magnetic Circuit Analysis of Single-Phase Flux-Switching Permanent-Magnet Motor  

Microsoft Academic Search

A 3-D lumped-parameter magnetic circuit model is developed for a single-phase flux-switching permanent-magnet motor. Particular attention is given to representing the complex air-gap flux paths by equivalent permeances so as to accurately model the asymmetry in the air-gap field distribution and to determine the back-EMF and inductance waveforms, as well as the average static torque. Leakage fluxes external to the

Yu Chen; Z. Q. Zhu; David Howe

2008-01-01

64

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

2013-01-01

65

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

66

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

67

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

68

Carbon Nanotube Device Modeling and Circuit Simulation  

Microsoft Academic Search

The development of new technology requires tools at all levels of abstraction. Modeling tools for detailed calculations of the energy band diagrams and device current–voltage characteristics [1] are essential first steps for device physics understanding. At the same time, modeling tools at higher levels of abstraction are required for device design space exploration and circuit design. As an example, for

H.-S. Philip Wong; Albert Lin; Jie Deng; Arash Hazeghi; Tejas Krishnamohan; Gordon Wan

69

High bandwidth magnetically isolated signal transmission circuit  

NASA Technical Reports Server (NTRS)

Many current electronic systems incorporate expensive or sensitive electrical components. Because electrical energy is often generated or transmitted at high voltages, the power supplies to these electronic systems must be carefully designed. Power supply design must ensure that the electrical system being supplied with power is not exposed to excessive voltages or currents. In order to isolate power supplies from electrical equipment, many methods have been employed. These methods typically involve control systems or signal transfer methods. However, these methods are not always suitable because of their drawbacks. The present invention relates to transmitting information across an interface. More specifically, the present invention provides an apparatus for transmitting both AC and DC information across a high bandwidth magnetic interface with low distortion.

Repp, John Donald (Inventor)

2005-01-01

70

Alternating current circuit theory and pulsed NMR (Nuclear Magnetic Resonance)  

NASA Astrophysics Data System (ADS)

Pulsed NMR, by definition, deals with time varying excitations. These excitations, supplied by resonant circuits which provide a pulse of radiofrequency (frequencies in the megahertz region) power to a resonant circuit containing, among other things, a coil of wire, or inductor, in which a sample under investigation is placed for purposes of the nuclear magnetic resonance experiment. There are therefore two features of the pulse NMR experiment. First is the fact that we have available a source of continuous wave (CW) alternating current at some angular frequency, omega, measured in radians per second. This source is generally supplied by an ultrastable device called a frequency synthesizer. The second feature of the pulsed NMR experiment is that the sample is not continuously irradiated, but a pulse of radiofrequency oscillation is applied to the sample. This report discusses alternating current theory, resonant circuits and the equipment used in this experiment.

Gerstein, B. C.

1987-06-01

71

A plasma model for reversed field pinch circuit design  

NASA Astrophysics Data System (ADS)

A plasma model has been developed for use in the design of circuits for reversed field pinch experiments. The magnetic field is assumed to evolve through a given series of relaxed states with the plasma resistivity specified as a function of time. At any instant the magnetic field configuration is determined by the field energy and the toroidal flux. If the Bessel function model is chosen as the relaxed state then the magnetic helicity can be used as an alternative to the magnetic energy without altering the results. Simulations of discharges on ZETA and ETA BETA II are presented. By suitable choices of the relaxed field configuration and plasma resistivity it is possible to obtain close agreement with the experimental waveforms. Application to the proposed RFX device is discussed.

Johnston, J. W.

1981-03-01

72

Computation of flux switching in magnetic circuits  

Microsoft Academic Search

A number of physical and semiempirical flux-switching models that have appeared in the literature are reviewed briefly and classified. A thin ferrite core is switched by essentially a step mmf (with short rise time Tr). Three components of the totaldot{phi}(t)are distinguished and semiempirical models are proposed for each : 1) an initial elasticdot{phi}spike during the rise time ofF, dot{phi}_{epsilon} =

DAVID NITZAN

1965-01-01

73

Modeling NAND Flash Memories for Circuit Simulations  

Microsoft Academic Search

In this paper, we will present the basic structure and the parameter extraction procedure for a compact model of a NAND Flash\\u000a memory string working in Spicelike circuit simulators. To the author knowledge, this is the first Spice-like model of a NAND\\u000a Flash memory string. This model is modular and simple to be implemented. It will allow accurately reproducing both

L. Larcher; A. Padovani; P. Pavan; I. Rimmaudo; A. Calderoni; G. Molteni; F. Gattel; P. Fantini

74

Bjt Modeling for Circuit Simulation  

NASA Astrophysics Data System (ADS)

Physical models for transport mechanisms important in bipolar transistors are developed, implemented in SPICE3 for DC, AC, and transient analyses, and assessed with numerical device simulations. The analytical model of quasi-saturation, or base -push-out, is derived for all current levels. Deficiencies in previous quasi-saturation models are revealed and overcome. The quasi-saturation model is based on a derivation of the current-induced-base charge and the electric field in the collector for all bias conditions. Physical models for base-width modulation (BWM) at the collector-base (cb) junction and impact ionization in the collector are formulated as functions of the electric field; inclusion of these two effects greatly improves the accuracy in the output resistance. The impact ionization model gives a first -order description of avalanche breakdown, or snapback. The dynamic charge storage effects are investigated in detail with AC and transient analyses. The proper partitioning of the dynamic charging currents is made possible by the addition of an internal collector node and increases accuracy especially under quasi-saturation conditions. The cb junction capacitance and the cb junction transit time tau _{cv} are expressed as functions of the field E_1 at the cb junction. As E_1 decreases with increasing current due to the Kirk effect, the variable tau _{cv} and the BWM effect on the base-diffusion charge each can cause f_ {T} to fall-off at a current several times below that for the onset of quasi-saturation, which causes a more rapid f_{T} fall -off. The current-induced-base charge significantly reduces the effective base resistance as the dynamic base current flows laterally through the current-induced-base. Simulation results suggest that an AC emitter crowding model previously derived for low injection conditions is a good approximation even under base-push-out conditions. The delay time approach and the quasi-static charge-partition approach are compared; the former is found to be better in simulating the high frequency effects due to non-quasi-static conditions in the quasi-neutral base and current-induced-base regions. A non-quasi-static model for the charge in the quasi-neutral base region is developed and implemented in SPICE3 for transient analysis. The methodology to solve for the instantaneous carrier distribution by a series solution including all injection levels and the effect of the built-in field is presented. The solution applies for forward and reverse modes of operation. Analytic equations for the instantaneous base charge partitions are derived for the calculation of the instantaneous node currents. For switching times comparable to the base transit time, the non-quasi-static model is significantly more accurate than the Gummel-Poon model and previous quasi-static charge -partition models, as verified with numerical device simulations.

Szeto, Clement Keung

75

An improved magnetic snubber circuit for the diode reverse recovery in DC-to-DC converters  

Microsoft Academic Search

This paper presents an improved magnetic snubber circuit for the diode reverse recovery in DC-to-DC power converters. The proposed circuit reduces effectively the core loss of the magnetic snubber. In addition, this circuit improves the control characteristics of the zero-voltage-switching converter using saturable inductors controlled by PFM. The operation of this circuit is described by use of equivalent circuits and

Kazurou Harada; Y. Ishihara; Toshiyukitodaka

1998-01-01

76

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

SciTech Connect

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

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

2012-09-20

77

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

78

Circuits  

NSDL National Science Digital Library

Students are introduced to several key concepts of electronic circuits. They learn about some of the physics behind circuits, the key components in a circuit and their pervasiveness in our homes and everyday lives. Students learn about Ohm's law and how it is used to analyze circuits.

Integrated Teaching And Learning Program

79

Circuit Model for Characterizing the Nearly Linear Behavior of Avalanche Diodes in Amplifier Circuits.  

National Technical Information Service (NTIS)

A nonlinear circuit model for avalanche diodes is proposed. The model was derived by assuming that the bias dependence of the elements in a known small-signal equivalent-circuit model for existing diodes arises in a manner consistent with the theory of an...

D. F. Peterson D. H. Steinbrecher

1972-01-01

80

The comparison of test circuits with arc models  

SciTech Connect

The arc-circuit interaction plays an important role in the current interrupting process of High-Voltage Circuit Breakers. For the development of circuit breakers, testing in the High Power Laboratory is necessary. For UHV circuit breakers new test circuits have to be developed. The design and development of new synthetic circuits relies on computer simulations only. A correct representation or the current zero behavior of the circuit breaker by means or an arc model is absolutely necessary. In this paper arc modeling, and the development of new test circuits are discussed and measurements of arc voltage and arc current are presented for two 72 kV SF{sub 6} power circuit breakers.

Sluis, L. van der [Delft Univ. of Technology (Netherlands). Power System Lab.] [Delft Univ. of Technology (Netherlands). Power System Lab.; Rutgers, W.R. [KEMA, Arnhem (Netherlands)] [KEMA, Arnhem (Netherlands)

1995-01-01

81

Live Imaging of Neuronal Connections by Magnetic Resonance: Robust Transport in the Hippocampal-Septal Memory Circuit in a Mouse Model of Down Syndrome  

PubMed Central

Connections from hippocampus to septal nuclei have been implicated in memory loss and the cognitive impairment in Down syndrome (DS). We trace these connections in living mice by Mn2+ enhanced 3D MRI and compare normal with a trisomic mouse model of DS, Ts65Dn. After injection of 4 nl of 200 mM Mn2+ into the right hippocampus, Mn2+ enhanced circuitry was imaged at 0.5, 6, and 24 hr in each of 13 different mice by high resolution MRI to detect dynamic changes in signal over time. The pattern of Mn2+ enhanced signal in vivo correlated with the histologic pattern in fixed brains of co-injected 3kD rhodamine-dextranamine, a classic tracer. Statistical parametric mapping comparing intensity changes between different time points revealed that the dynamics of Mn2+ transport in this pathway were surprisingly more robust in DS mice than in littermate controls, with statistically significant intensity changes in DS appearing at earlier time points along expected pathways. This supports reciprocal alterations of transport in the hippocampal-forebrain circuit as being implicated in DS and argues against a general failure of transport. This is the first examination of in vivo transport dynamics in this pathway and the first report of elevated transport in DS.

Bearer, Elaine L.; Zhang, Xiaowei; Jacobs, Russell E.

2007-01-01

82

Physical and circuit modeling of coupled open quantum systems  

Microsoft Academic Search

Recently, we proposed new complementary logic circuits using nano-scale coupled quantum wells [12]. In this paper, we explore a systematic way of modeling the device at physical and circuit levels for nano-scale coupled open quantum systems. The physical interface between coupled and uncoupled regions is considered as a junction where electrons can be coherently injected. The circuit model treats the

Yasunao Katayama

2005-01-01

83

CIRC: a specialized circuit analysis computer simulation program for a high explosive generator model  

Microsoft Academic Search

CIRC is a fast computer model for the simulation of the performance of a high explosive helical magnetic flux compression generator and a load. These separate models are joined by a lumped circuit solved by CIRC as a multinode network equation with time as the independent variable. In this paper the generator model, as it currently exists, will be detailed.

1986-01-01

84

Coupling single-molecule magnets to quantum circuits  

NASA Astrophysics Data System (ADS)

In this work we study theoretically the coupling of single-molecule magnets (SMMs) to a variety of quantum circuits, including microwave resonators with and without constrictions and flux qubits. The main result of this study is that it is possible to achieve strong and ultrastrong coupling regimes between SMM crystals and the superconducting circuit, with strong hints that such a coupling could also be reached for individual molecules close to constrictions. Building on the resulting coupling strengths and the typical coherence times of these molecules (? ?s), we conclude that SMMs can be used for coherent storage and manipulation of quantum information, either in the context of quantum computing or in quantum simulations. Throughout the work we also discuss in detail the family of molecules that are most suitable for such operations, based not only on the coupling strength, but also on the typical energy gaps and the simplicity with which they can be tuned and oriented. Finally, we also discuss practical advantages of SMMs, such as the possibility to fabricate the SMMs ensembles on the chip through the deposition of small droplets.

Jenkins, Mark; Hümmer, Thomas; José Martínez-Pérez, María; García-Ripoll, Juanjo; Zueco, David; Luis, Fernando

2013-09-01

85

Circuit modeling of coupled-cavity semiconductor lasers  

Microsoft Academic Search

In this work we present a circuit model of coupled cavity semiconductor laser. The model is based on the two axial coupled semiconductor rate equations. The results obtained by this circuit model and the analysis of the rate equation in the small signal regime are discussed showing good agreement between both models.

Horacio Lamela; Guillermo Carpintero; Pablo Acedo

1996-01-01

86

Short-circuit energy dissipation modeling for submicrometer CMOS gates  

Microsoft Academic Search

A significant part of the energy dissipation in static complementary metal-oxide-semiconductor (CMOS) structures is due to short-circuit currents. In this paper, an accurate analytical model for the CMOS short-circuit energy dissipation is presented. First, the short-circuit energy dissipation of the CMOS inverter is modeled. The derived model is based on analytical expressions of the inverter output waveform which include the

L. Bisdounis; O. Koufopavlou

2000-01-01

87

Modeling of Flux Switching Permanent Magnet Machines With Fourier Analysis  

Microsoft Academic Search

For applications demanding a high torque density and high speed capability, the flux switching permanent magnet machine is an excellent candidate. However, the double salient structure and nonlinear behavior increases the challenge to model the magnetic field distribution and torque output. To date, only the magnetic equivalent circuit (MEC) is employed to model the magnetic field in an analytical manner.

Bart L. J. Gysen; Esin Ilhan; Koen J. Meessen; Johannes J. H. Paulides; Elena A. Lomonova

2010-01-01

88

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

89

Circuital and numerical modeling of electrostatic discharge generators  

Microsoft Academic Search

The paper provides two accurate and efficient models of electrostatic discharge (ESD) 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

Spartaco Caniggia; F. Maradei

2005-01-01

90

Computation of magnetic suspension of maglev systems using dynamic circuit theory  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

91

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

92

Circuit model for segmented traveling-wave electroabsorption modulators  

NASA Astrophysics Data System (ADS)

In this paper, a circuit model of a segmented traveling-wave Electroabsorption modulators is presented for the circuit level simulation of single device or Optoelectronic Integrated Circuits (OEIC) including modulators. Using this model, the frequency response of segmented TEAM are analyzed using HSPICE. The analysis indicates that STEAM can achieve much wider bandwidth than the LEAM and TWEAM counterparts, with a small penalty in E/O conversion gain if low loss passive optical waveguide is available.

Abedi, K.; Ahmadi, V.; Sheikhi, M. H.; Gholmohammadi, S.; Yavari, M. H.

2008-03-01

93

Analysis of quench properties of the Q3 magnets with and without open circuit heater elements  

SciTech Connect

The Q3 magnets have 2 independent heater elements that are energized by the quench protection system. One heater element in the Q3 magnet at A4 became an open circuit after the initial cooldown. Recently the second element became an open circuit. The Q3 magnet at A4 is powered in series with a Q3 magnet at B1. The heaters in the magnet at B1 are still intact. The purpose of this study is to determine if the magnet circuit can be operated without undue risk of damage to the magnets. The risk of damage to the magnet at A4 is less of a concern since repairing the heaters is expected to be a major effort in any event. There is one spare Q3 magnet.

Lackey, Sharon; Marriner, John; Pfeffer, Howie; /Fermilab

1995-11-01

94

Electrical Circuit Modeling for Somatosensory Evoked Fields in Magnetoencephalogram  

NASA Astrophysics Data System (ADS)

We measured somatosensory evoked fields (SEFs) by applying on electric stimulus to the right finger (medium nerve and ulnar nerve) and the right ankle (posterior tibial nerve) with a 39-channel SQUID system, which can measure magnetic-field components perpendicular (Br) and tangential to the scalp (B?, B?) simultaneously. To investigate the relationship between phase lag and stimulus repetition frequency (SRF), the delay time of a component synchronized with the SRFs was calculated by convoluting the reference signal and the measured SEF. The phase lag was linear to SRF for at least three different ranges of the SRFs in each SEF data. We simulated the SEF responses based on the results of phase-lag characteristics and determined the parameters for modeling. To quantitatively characterize the component of SEF, we proposed electric circuit model for the characteristics of phase-lag of the SEF with stimuli frequency.

Ishihara, Shinichi; Tanaka, Keita; Uchikawa, Yoshinori; Kobayashi, Koichiro

95

Determination of Generalized Permeability Function and Field Energy Density in Artificial Magnetics Using the Equivalent-Circuit Method  

NASA Astrophysics Data System (ADS)

The equivalent circuit model for artificial magnetic materials based on various arrangements of split rings is generalized by taking into account losses in the substrate or matrix material. It is shown that a modification is needed to the known macroscopic permeability function in order to correctly describe these materials. Depending on the dominating loss mechanism (conductive losses in metal parts or dielectric losses in the substrate) the permeability function has different forms. The proposed circuit model and permeability function are experimentally validated. Furthermore, starting from the generalized circuit model we derive an explicit expression for the electromagnetic field energy density in artificial magnetic media. This expression is valid at low frequencies and in the vicinity of the resonance also when dispersion and losses in the material are strong. The presently obtained results for the energy density are compared with the results obtained using different methods.

Ikonen, Pekka M. T.; Tretyakov, Sergei A.

2007-01-01

96

Influence of Model of Circuit-breaker on Very Fast Transient Over-voltage  

NASA Astrophysics Data System (ADS)

Based on a power station, two transient models of circuit-breaker is employed and the very fast transient over-voltage in 550kVGIS is calculated and simulated in the consideration of two different models of circuit-breaker, applying the Electro-Magnetic Transient Program in this paper. The impact of varied models on the values and the frequencies of VFTO in the GIS is intensively focused. It is indicated that the two models of circuit breaker have different effects on the peak voltage of VFTO for different nodes. Under the two operation modes, the deviations of the most voltage spectrum frequency are 5.8% and 0 at circuit breaker. Comparing to the results of the two operation modes, the deviation of operating DS21 are higher than that of operating DS22 because of the changing current flow.

Na, Wang; Yu, Liang

97

The Influence of Vacuum Circuit Breakers and Different Motor Models on Switching Overvoltages in Motor Circuits  

NASA Astrophysics Data System (ADS)

Switching of induction motors with vacuum circuit breakers continues to be a concern. In this paper the influence on statistical overvoltages of the stochastic characteristics of vacuum circuit breakers, high frequency models of motors and transformers, and network characteristics, including cable lengths and network topology are evaluated and a general view of the overvoltages phenomena is presented. Finally, a real case study on the statistical voltage levels and risk-of-failure resulting from switching of a vacuum circuit breaker in an industrial installation in Hong Kong is presented.

Wong, Cat S. M.; Snider, L. A.; Lo, Edward W. C.; Chung, T. S.

98

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

99

Modeling and optimization of complex photonic resonant cavity circuits  

Microsoft Academic Search

The simple method for modeling of circuits of weakly coupled lossy resonant cavities, previously developed in quantum mechanics, is generalized to enable calculation of the transmission and reflection amplitudes and group delay of light. Our result is the generalized Breit-Wigner formula, which has a clear physical meaning and is convenient for fast modeling and optimization of complex resonant cavity circuits

Michael Sumetsky; Benjamin J. Eggleton

2003-01-01

100

Circuit model for characterizing the nearly linear behavior of avalanche diodes in amplifier circuits  

NASA Technical Reports Server (NTRS)

A nonlinear circuit model for avalanche diodes is proposed. The model was derived by assuming that the bias dependence of the elements in a known small-signal equivalent-circuit model for existing diodes arises in a manner consistent with the theory of an idealized Read-type device. The model contains a nonlinear R-L branch, a controlled source, and a linear depletion capacitance. The model is used in the nearly linear sense to predict intermodulation distortion and gain compression in avalanche diode amplifiers. Computed results for amplifiers with existing diodes are shown to be in good agreement with experiment.

Penfield, P., Jr.; Peterson, D. F.; Steinbrecher, D. H.

1972-01-01

101

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

102

Circuits  

NSDL National Science Digital Library

Contains 5 Physlets designed to solve the common AC and DC circuit problems. In addition to the usual RC and LRC simulations, there is an applet to plot non-linear I vs V response and an applet to plot frequency response.

Christian, Wolfgang; Belloni, Mario

2008-02-09

103

High Resolution PV Power Modeling for Distribution Circuit Analysis  

SciTech Connect

NREL has contracted with Clean Power Research to provide 1-minute simulation datasets of PV systems located at three high penetration distribution feeders in the service territory of Southern California Edison (SCE): Porterville, Palmdale, and Fontana, California. The resulting PV simulations will be used to separately model the electrical circuits to determine the impacts of PV on circuit operations.

Norris, B. L.; Dise, J. H.

2013-09-01

104

3-D finite element analysis of magnetic force on the arc for arc chamber design of molded case circuit breaker  

NASA Astrophysics Data System (ADS)

It is necessary for the optimum design of arc quenching chamber in the molded case circuit breakers to analyze magnetic force acting on the arc in the chamber. The magnetic blowout forces and the distribution of magnetic field induced by arc current depend on the shape, arrangement, and kinds of material of grids in the chamber. The effective method to design V-slotted iron grid in the arc quenching chamber is discussed in this paper. The magnetic blowout force and flux density were obtained by using the 3-D finite element method considering non-linearity of iron grids. The grid model designed optimally was also verified by means of the interruption performances test. It is shown that our design method is a useful tool for design of arc quenching chamber in the circuit breakers.

Lim, Kee-Joe; Kang, Seong-Hwa; Lee, Un-Yong; Song, Hee-Chan

2001-06-01

105

Optimization of electromagnetic devices: circuit models, neural networks and gradient methods in concert  

Microsoft Academic Search

Optimization in designing electromagnetic products is now increasingly better understood. As opposed to classical models of magnetic circuits, today, gradient techniques for mathematical optimization have been proposed and are used. These techniques, while being expensive, are exact. More recently, artificial neural networks have been suggested, but they, work best only if the data set of parameter-set, performance pairs for training

S. R. H. Hoole; M. K. Haldar

1995-01-01

106

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

107

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

108

Resonant circuits for hyperthermia excited by RF magnetic field of MRI  

Microsoft Academic Search

The hyperthermia using a magnetic resonance imaging (MRI) is proposed. A resonant circuit consisting of a closed connection of coil and capacitor was used as an implant heated by an external ac magnetic field. Its resonant frequency was 63.9 MHz. The maximum temperature rise of 40°C was obtained from the thermally insulated resonant circuit by applying the field of 0.034

Megumi Morita; Takeshi Inoue; Tsutomu Yamada; Yasushi Takemura; Tetsu Niwa; Tomio Inoue

2005-01-01

109

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

110

Circuit Model for Gun Driven Spheromaks.  

National Technical Information Service (NTIS)

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. ...

K. I. Thomassen

2000-01-01

111

Circuit Model for Gun Driven Spheromaks  

Microsoft Academic Search

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

Thomassen

2000-01-01

112

An equivalent circuit model for two-stage operational amplifiers  

Microsoft Academic Search

The two-pole equivalent-circuit model for frequency compensation has been improved to provide more accurate unity-gain phase margin calculations for a two-stage operational amplifier when the second-stage pole is dominant. The increased accuracy allows for minimum settling time compensation, which gives maximum speed in switched-capacitor circuit applications. The model also clarifies some confusion that has existed previously regarding pole-splitting compensation. SPICE2

Howard C. Yang; David J. Allstot

1988-01-01

113

Embedded Micro-Flux-Gate Magnetic Sensor in Printed Circuit Board  

Microsoft Academic Search

We have developed a micro-flux-gate magnetic sensor using a new printed circuit board (PCB) technology. The flux-gate sensor consists of five PCB stack layers including one layer of magnetic core and four layers of excitation and pickup coils. The center layer as a magnetic core is made of a micropatterned amorphous magnetic ribbon with an extremely high DC permeability of

Won-Youl Choi; Jun-Sik Hwang; Sang-On Choi

2005-01-01

114

Advances in low-voltage circuit breaker modelling  

NASA Astrophysics Data System (ADS)

This paper is devoted to the study of electric arc behaviour under the influence of an external magnetic field. This situation is close to that occurring in a low-voltage circuit breaker where an arc, after ignition, is submitted to the magnetic field of the circuit. After a discussion of the literature, we present our contribution. Two different methods are compared to take the magnetic effects into account. Arc displacement in the geometry studied is dealt within a specific development presented in this paper. We show the influence of the nature of the gas on the arc velocity and on possible re-strike using air and an air-PA6 mixture as the plasma gas.

Swierczynski, B.; Gonzalez, J. J.; Teulet, P.; Freton, P.; Gleizes, A.

2004-02-01

115

Statistical modeling of device mismatch for analog MOS integrated circuits  

Microsoft Academic Search

A generalized parameter-level statistical model, called statistical MOS (SMOS), capable of generating statistically significant model decks from intra- and inter-die parameter statistics is described. Calculated model decks preserve the inherent correlations between model parameters while accounting for the dependence of parameter variance on device separation distance and device area. Using a Monte Carlo approach to parameter sampling, circuit output means

Christopher Michael; Mohammed Ismail

1992-01-01

116

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

117

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

118

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

119

Hybrid Quantum Magnetism in Circuit QED: From Spin-Photon Waves to Many-Body Spectroscopy  

NASA Astrophysics Data System (ADS)

We introduce a model of quantum magnetism induced by the nonperturbative exchange of microwave photons between distant superconducting qubits. By interconnecting qubits and cavities, we obtain a spin-boson lattice model that exhibits a quantum phase transition where both qubits and cavities spontaneously polarize. We present a many-body ansatz that captures this phenomenon all the way, from a the perturbative dispersive regime where photons can be traced out, to the nonperturbative ultrastrong coupling regime where photons must be treated on the same footing as qubits. Our ansatz also reproduces the low-energy excitations, which are described by hybridized spin-photon quasiparticles, and can be probed spectroscopically from transmission experiments in circuit QED, as shown by simulating a possible experiment by matrix-product-state methods.

Kurcz, Andreas; Bermudez, Alejandro; García-Ripoll, Juan José

2014-05-01

120

Hybrid Quantum Magnetism in Circuit QED: From Spin-Photon Waves to Many-Body Spectroscopy.  

PubMed

We introduce a model of quantum magnetism induced by the nonperturbative exchange of microwave photons between distant superconducting qubits. By interconnecting qubits and cavities, we obtain a spin-boson lattice model that exhibits a quantum phase transition where both qubits and cavities spontaneously polarize. We present a many-body ansatz that captures this phenomenon all the way, from a the perturbative dispersive regime where photons can be traced out, to the nonperturbative ultrastrong coupling regime where photons must be treated on the same footing as qubits. Our ansatz also reproduces the low-energy excitations, which are described by hybridized spin-photon quasiparticles, and can be probed spectroscopically from transmission experiments in circuit QED, as shown by simulating a possible experiment by matrix-product-state methods. PMID:24856680

Kurcz, Andreas; Bermudez, Alejandro; García-Ripoll, Juan José

2014-05-01

121

PEEC modelling of toroidal magnetic inductor in frequency domain  

Microsoft Academic Search

In this paper, a detailed 3D Partial Element Equivalent Circuit (PEEC) model of a toroidal coil with a magnetic core is developed. The PEEC problem in the presence of magnetic materials is solved in the frequency domain via a magnetic current\\/charge approach, i.e. replacing the magnetized objects by a distribution of equivalent fictitious magnetic currents\\/charges in free space. The simulation

I. F. Kovac?evic?; A. Mu?sing; J. W. Kolar

2010-01-01

122

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

123

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

124

Modelling of circuit breakers in the Electromagnetic Transients Program  

Microsoft Academic Search

The recent publication of experimental and theoretical results from verified arc models has made possible the implementation and testing of a dynamic circuit-breaker model using the Electromagnetic Transients Program (EMTP). An estimator was developed to obtain model parameters from test data. Results obtained with the estimator are given, and its data requirements are specified. To illustrate an application of the

V. Phaniraj; A. G. Phadke

1988-01-01

125

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

126

Stochastic interpolation model of the medial superior olive neural circuit.  

PubMed

This article presents a stochastic model of binaural hearing in the medial superior olive (MSO) circuit. This model is a variant of the slope encoding models. First, a general framework is developed describing the elementary neural operations realized on spike trains in individual parts of the circuit and how the neurons converging onto the MSO are connected. Random delay, coincidence detection of spikes, divergence and convergence of spike trains are operations implemented by the following modules: spike generator, jitter generator, and coincidence detector. Subsequent processing of spike trains computes the sound azimuth in the circuit. The circuit parameters that influence efficiency of slope encoding are studied. In order to measure the overall circuit performance the concept of an ideal observer is used instead of a detailed model of higher relays in the auditory pathway. This makes it possible to bridge the gap between psychophysical observations in humans and recordings taken of small rodents. Most of the results are obtained through numerical simulations of the model. PMID:21920505

Sanda, Pavel; Marsalek, Petr

2012-01-24

127

HID-lamp igniter using a two-stage magnetic-pulse-compression circuit  

Microsoft Academic Search

This paper proposes a high-intensity-discharge (HID) lamp igniter using a two-stage magnetic-pulse compression (MPC) circuit. The circuit operation is analyzed, and an optimal design procedure for selecting the saturable reactors and energy-storage capacitors is derived. Experimental verification is also given. This igniter can generate voltage pulses whose peak value and pulse width are 50 kV and 800 ns, respectively

H. Kakehashi; M. Habu; T. Ninomiya; H. Ogasawara; Y. Ohta

1998-01-01

128

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

129

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

130

A simple MOSFET model for circuit analysis  

Microsoft Academic Search

A simple, general, yet realistic MOSFET model, the nth power law MOSFET model, is introduced. The model can express I- V characteristics of short-channel MOSFETs at least down to 0.25-?m channel length and of resistance inserted MOSFETs. The model evaluation time is about 1\\/3 of the evaluation time of the SPICE3 MOS LEVEL3 model. The model parameter extraction is done

Takayasu Sakurai; A. Richard Newton

1991-01-01

131

Magnetic Bar Field Model  

NSDL National Science Digital Library

The EJS Magnetic Bar Field Model shows the field of a bar magnet and has a movable compass that reports the magnetic field values. The bar magnet model is built by placing a group of magnetic dipoles along the bar magnet. 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 Bar 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_MagneticBarField.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; Franciscouembre; Cox, Anne

2009-09-18

132

Handbook of modeling for circuit analysis including radiation effects  

Microsoft Academic Search

This handbook is a compilation and organization of previous research in computer modeling of semiconductor devices. It is designed to serve as a reference for the analyst who must analyze the effects of nuclear radiation on electronic circuits. It uses a modular approach wherein the analyst uses the simplest model which will yield the desired accuracy. The latest technology in

D. R. Alexander; P. A. Young; R. J. Antinone; R. Simon

1979-01-01

133

A Unified Circuit Model for the Polysilicon Thin Film Transistor  

Microsoft Academic Search

This paper describes a unified approach to modelling the polysilicon thin film transistor (TFT) for the purposes of circuit design. The approach uses accurate methods of predicting the channel conductance and then fitting the resulting data with a polynomial. Two methods are proposed to find the channel conductance: a device model and measurement. The approach is suitable because the TFT

M. J. Izzard; P. Migliorato; W. I. Milne

1991-01-01

134

Modelling of alternating-current machines having multiple rotor circuits  

Microsoft Academic Search

The modeling of a synchronous or an asynchronous machine forms the basis of simulation investigations made with high-powered computers. Many phenomena and processes require corresponding refinement of the models used, and an increase in input in the form of fictive rotor circuits. A method is presented which has been tested out over a relatively long period of time. The general

I. M. Canay

1993-01-01

135

ISFET-neuron junction: circuit models and extracellular signal simulations.  

PubMed

Purpose of this paper is to characterize the Ion-Sensitive Field-Effect Transistors (ISFET)-neuron junction, based on the equivalent electric-circuit approach. As a result, recording of action potentials can be simulated with a general-purpose circuit simulation program such as HSPICE. The neuronal electrical activity, extracellularly recorded by the ISFET, is analyzed as a function of the physical-chemical and geometric ISFET parameters, of the ionic currents in the neuron, and of the neuro-electronic junction parameters such as the sealing resistance, double-layer capacitance, and general adhesion conditions. The models of the neuron, of the coupling circuit, and of the ISFET implemented in HSPICE are first described. These models are then used to simulate the behavior of the junction between a patch of neuronal membrane (described by the compartmental model) and the ISFET. PMID:15093221

Martinoia, Sergio; Massobrio, Paolo

2004-06-15

136

Modeling of opto-electronics in complex photonic integrated circuits  

NASA Astrophysics Data System (ADS)

This work addresses a versatile modeling of complex photonic integrated circuits (PICs) including optical and electrical sub-elements. We introduce a new family of electrical elements, together with a novel electronic-photonic co-design, that complements current capabilities of photonic circuit simulators. This is illustrated with the modeling of complex electric circuits contained in photonic devices. Simulations of the interaction between electrical and optical parts allow the analysis of unwanted effects such as reflections due to impedance mismatching, as well as the optimization of the PIC as a whole. We illustrate the functionalities of our approach through application examples. As a use case, we present a model of the electrical driver for a monolithically-integrated InP transmitter developed in frame of the European research project MIRTHE and the analysis of the driver and the EA-Modulator interplay.

Arellano, C.; Mingaleev, S.; Koltchanov, I.; Richter, A.

2014-03-01

137

Acoustic-phonon-based interaction between coplanar quantum circuits in a magnetic field  

NASA Astrophysics Data System (ADS)

We explore the acoustic-phonon-based interaction between two neighboring coplanar circuits containing semiconductor quantum point contacts in a perpendicular magnetic field B . In a drag-type experiment, a current flowing in one of the circuits (unbiased) is measured in response to an external current in the other. In moderate B the sign of the induced current is determined solely by the polarity of B . This indicates that the spatial regions where the phonon emission/reabsorption is efficient are controlled by magnetic field. The results are interpreted in terms of nonequilibrium transport via skipping orbits in a two-dimensional electron system.

Prokudina, M. G.; Khrapai, V. S.; Ludwig, S.; Kotthaus, J. P.; Tranitz, H. P.; Wegscheider, W.

2010-11-01

138

Effect of Short-Circuit Voltage Profile on the Transient Performance of Saturated Permanent Magnet Synchronous Motors  

Microsoft Academic Search

When permanent magnet synchronous motors are subjected to short-circuit at their terminals, the accurate calculation of the motor transient performance depends on the short- circuit voltage profile and the saturation condition of the main flux paths. In this paper, a voltage profile due to a short-circuit at the motor terminals is proposed where the motor terminal voltage requires a certain

Shahram Najafi; Narayan C. Kar

2007-01-01

139

Surrogate Modeling of RF Circuit Blocks  

Microsoft Academic Search

\\u000a Surrogate models are a cost-effective replacement for expensive computer simulations in design space exploration. Literature\\u000a has already demonstrated the feasibility of accurate surrogate models for single radio frequency (RF) and microwave devices.\\u000a Within the European Marie Curie project O-MOORE-NICE! (Operational Model Order Reduction for Nanoscale IC Electronics) we\\u000a aim to investigate the feasibility of the surrogate modeling approach for entire

Luciano De Tommasi; Dirk Gorissen; Jeroen A. Croon; Tom Dhaene

140

Magnetized cosmological model  

SciTech Connect

The object of this paper is to investigate the behavior of the magnetic field in a cosmological model for perfect fluid distribution. The magnetic field is due to an electric current produced along the /chi/ axis. It is assumed that expansion (/theta/) in the model is proportional to sigma/sup 1//sub 1/, the eigenvalue of the shear tensor sigma /sup j/ /sub i/. The behavior of the model when the magnetic field tends to zero and other physical properties are also discussed.

Bali, R.

1986-07-01

141

[Dual neural circuit model of reading and writing].  

PubMed

In the hypothetical neural circuit model of reading and writing that was initially proposed by Dejerine and subsequently confirmed by Geschwind, the left angular gyrus was considered as a unique center for processing letters. Japanese investigators, however, have repeatedly pointed out that this angular gyrus model cannot fully explain the disturbances observed in reading and writing Kanji letters in Japanese patients with various types of alexia with or without agraphia. In 1982, I proposed a dual neural circuit model of reading and writing Japanese on the basis of neuropsychological studies on the various types of alexia with or without agraphia without aphasia. This dual neural circuit model proposes that apart from the left angular gyrus which was thought to be a node for phonological processing of letters, the left posterior inferior temporal area, also acts as a node for semantic processing of letters. Further investigations using O15-PET activation on normal subjects revealed that the left middle occipital gyrus (area 19 of Brodmann) and the posterior portion of the left inferior temporal gyrus (area 37 of Brodmann) are the cortical areas responsible for reading Japanese letters; the former serving for phonological reading and the latter for semantic reading. This duality of the neural circuit in processing letters was later applied to explain disturbances in reading English, and was finally accepted as a valid model for other alphabetic letter systems too. PMID:21817173

Iwata, Makoto

2011-08-01

142

A new approach to magnetic circuit analysis and its application to the optimal design of a bi-directional magnetorheological brake  

Microsoft Academic Search

This paper proposes a new approach to modeling the magnetic circuit of an MR brake and applies it to explore an engineering optimization problem. The MR brake used in this work is a bi-directional type whose range of braking torque varies from negative to positive values. The model of the bi-directional MR brake can be split into two components: the

Phuong-Bac Nguyen; Seung-Bok Choi

2011-01-01

143

Transmission Line and Equivalent Circuit Models for Plasmonic Waveguide Components  

Microsoft Academic Search

Modeling of waveguide junctions using transmission lines and lumped circuit elements is common practice in microwave networks. By the help of the scattering matrix formalism, it is possible to describe junction effects in a very concise way. Such a representation is crucial for the design of complex systems containing many interacting parts. Using scattering matrices, we characterize symmetric junctions between

S. E. Kocabas; Georgios Veronis; David A. B. Miller; Shanhui Fan

2008-01-01

144

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

145

A Wide Bandwidth Model for the Electrical Impedance of Magnetic BearingS  

NASA Technical Reports Server (NTRS)

Magnetic bearings are often designed using magnetic circuit theory. When these bearings are built, however, effects not included in the usual circuit theory formulation have a significant influence on bearing performance. Two significant sources of error in the circuit theory approach are the neglect of leakage and fringing effects and the neglect of eddy current effects. This work formulates an augmented circuit model in which eddy current and flux leakage and fringing effects are included. Through the use of this model, eddy current power losses and actuator bandwidth can be derived. Electrical impedance predictions from the model are found to be in good agreement with experimental data from a typical magnetic bearing.

Meeker, David C.; Maslen, Eric H.; Noh, Myounggyu D.

1996-01-01

146

Mapping and Cracking Sensorimotor Circuits in Genetic Model Organisms  

PubMed Central

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.

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

2013-01-01

147

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

148

Cardiopulmonary Circuit Models for Predicting Injury to the Heart  

NASA Astrophysics Data System (ADS)

Circuit models have been used extensively in physiology to describe cardiopulmonary function. Such models are being used in the DARPA Virtual Soldier (VS) Project* to predict the response to injury or physiological stress. The most complex model consists of systemic circulation, pulmonary circulation, and a four-chamber heart sub-model. This model also includes baroreceptor feedback, airway mechanics, gas exchange, and pleural pressure influence on the circulation. As part of the VS Project, Oak Ridge National Laboratory has been evaluating various cardiopulmonary circuit models for predicting the effects of injury to the heart. We describe, from a physicist's perspective, the concept of building circuit models, discuss both unstressed and stressed models, and show how the stressed models are used to predict effects of specific wounds. *This work was supported by a grant from the DARPA, executed by the U.S. Army Medical Research and Materiel Command/TATRC Cooperative Agreement, Contract # W81XWH-04-2-0012. The submitted manuscript has been authored by the U.S. Department of Energy, Office of Science of the Oak Ridge National Laboratory, managed for the U.S. DOE by UT-Battelle, LLC, under contract No. DE-AC05-00OR22725. Accordingly, the U.S. Government retains a non-exclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purpose.

Ward, Richard; Wing, Sarah; Bassingthwaighte, James; Neal, Maxwell

2004-11-01

149

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

150

The effects of spacing between garnet film and Permalloy overlay circuit in magnetic bubble devices  

Microsoft Academic Search

An experimental test set for magnetic bubble devices has been constructed in which the spacing between the garnet film and the Permalloy overlay is variable. The experimental uncertainty in spacing is approximatelypm.15mum, and spacings as small as.5mum have been attained. Bias margin data are presented which were taken at 1 Hz on a 20 micron period chevron circuit as a

Yu-Ssu Chen; T. Nelson

1972-01-01

151

Microfabrication of circuits for magnetic bubbles of diameter 1 mum and 2 mum  

Microsoft Academic Search

We describe microfabrication techniques for Permalloy circuits for magnetic bubbles of diameter 1 mum and 2 mum. Patterns are defined by electron beam on an x-ray mask. X-ray lithography and ion milling are employed to replicate the pattern in Permalloy.

R. K. Watts; H. M. Darley; J. B. Kruger; T. G. Blocker; D. C. Guterman; J. T. Carlo; D. C. Bullock; M. S. Shaikh

1976-01-01

152

Microfabrication of circuits for magnetic bubbles of diameter 1 ?m and 2 ?m  

Microsoft Academic Search

We describe microfabrication techniques for Permalloy circuits for magnetic bubbles of diameter 1 ?m and 2 ?m. Patterns are defined by electron beam on an x-ray mask. X-ray lithography and ion milling are employed to replicate the pattern in Permalloy.

R. K. Watts; H. M. Darley; J. B. Kruger; T. G. Blocker; D. C. Guterman; J. T. Carlo; D. C. Bullock; M. S. Shaikh

1976-01-01

153

BATTERIES AND BULBS, BOOK 2, CIRCUITS AND MAGNETS.  

ERIC Educational Resources Information Center

THIS TRIAL EDITION OF A TEACHER'S GUIDE, BOOK TWO IN A SERIES OF FOUR, IS INTENDED TO PROVIDE RESOURCE MATERIAL FOR AN INTRODUCTORY STUDY OF ELECTRICITY AND MAGNETISM. IT IS SUITABLE FOR ADAPTION TO VARIOUS LEVELS FROM GRADES 2-10. USED IN CONJUNCTION WITH THE OTHER VOLUMES, IT PROVIDES MATERIAL FOR A PROGRAM OF FROM 5 TO 40 WEEKS, DEPENDING ON…

1966

154

Transformer and load modeling in short circuit analysis for distribution systems  

Microsoft Academic Search

Accuracy of short circuit analysis depends on the modeling of transformers and loads. This paper addresses implementation of various transformer and load models in a short-circuit analysis for three-phase unbalanced distribution systems. Detailed transformer models are derived and incorporated into a production grade short circuit program with three different load models. Our studies show that different transformer connections, load models,

A. Tan; W.-H. E. Liu; D. Shirmohammadi

1997-01-01

155

Study of battery modeling using mathematical and circuit oriented approaches  

Microsoft Academic Search

Energy storage improves the efficiency and reliability of the electric utility system. The most common device used for storing electrical energy is batteries. To investigate power converter-based charge and discharge control of a battery storage device, effective battery models are critically needed. This paper presents a comparison study of mathematical and circuit-oriented battery models with a focus on lead-acid batteries

Shuhui Li; Bao Ke

2011-01-01

156

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

157

Development of circuit model for arcing on solar panels  

NASA Astrophysics Data System (ADS)

The increased requirements of payload capacity of the satellites have resulted in much higher power requirements of the satellites. In order to minimize the energy loss during power transmission due to cable loss, use of high voltage solar panels becomes necessary. When a satellite encounters space plasma it floats negatively with respect to the surrounding space plasma environment. At high voltage, charging and discharging on solar panels causes the power system breakdown. Once a solar panel surface is charged and potential difference between surface insulator and conductor exceeds certain value, electrostatic discharge (ESD) may occur. This ESD may trigger a secondary arc that can destroy the solar panel circuit. ESD is also called as primary or minor arc and secondary is called major arc. The energy of minor arc is supplied by the charge stored in the coverglass of solar array and is a pulse of typically several 100 ns to several 100 ?s duration. The damage caused by minor arc is less compared to major arcs, but it is observed that the minor arc is cause of major arc. Therefore it is important to develop an understanding of minor arc and mitigation techniques. In this paper we present a linear circuit analysis for minor arcs on solar panels. To study arcing event, a ground experimental facility to simulate space plasma environment has been developed at Facilitation Centre for Industrial Plasma Technologies (Institute for Plasma Research) in collaboration with Indian Space Research Organization's ISRO Satellite Technology Centre (ISAC). A linear circuit model has been developed to explain the experimental results by representing the coverglass, solar cell interconnect and wiring by an LCR circuit and the primary arc by an equivalent LR circuit. The aim of the circuit analysis is to predict the arc current which flows through the arc plasma. It is established from the model that the current depends on various parameters like potential difference between insulator and conductor, arc resistance, stored charge in the solar cell coverglass and the external capacitor that simulates wire harness. A close correlation between the experiments and circuit model results has been observed.

Mehta, Bhoomi K.; Deshpande, S. P.; Mukherjee, S.; Gupta, S. B.; Ranjan, M.; Rane, R.; Vaghela, N.; Acharya, V.; Sudhakar, M.; Sankaran, M.; Suresh, E. P.

2010-02-01

158

Modeling solar magnetic structures  

NASA Technical Reports Server (NTRS)

Some ideas in the theoretical study of force-free magnetic fields and magnetostatic fields, which are relevant to the effort of using magnetograph data as inputs to model the quasi-static, large-scale magnetic structures in the solar atmosphere are discussed. Basic physical principles will be emphasized. An attempt will be made to assess what we may learn, physically, from the models based on these ideas. There is prospect for learning useful physics and this ought to be an incentive for intensifying the efforts to improve vector magnetograph technology and to solve the basic radiative-transfer problems encountered in the interpretation of magnetograph raw data.

Low, B. C.

1985-01-01

159

High-Frequency-Measurement-Based Circuit Modeling and Power\\/Ground Integrity Evaluation of Integrated Circuit Packages  

Microsoft Academic Search

The frequency-variant characteristics of a pair of package power and ground net are experimentally investigated and modeled by using frequency-variant grid-type equivalent circuits, where each cell of the grid is modeled with vertically stacked RLC-ladder circuits. Various test patterns are designed and fabricated by employing a ball grid array (BGA) package process. Then the test patterns are characterized by using

Heungkyu Kim; Yungseon Eo

2008-01-01

160

A Corticothalamic Circuit Model for Sound Identification in Complex Scenes  

PubMed Central

The identification of the sound sources present in the environment is essential for the survival of many animals. However, these sounds are not presented in isolation, as natural scenes consist of a superposition of sounds originating from multiple sources. The identification of a source under these circumstances is a complex computational problem that is readily solved by most animals. We present a model of the thalamocortical circuit that performs level-invariant recognition of auditory objects in complex auditory scenes. The circuit identifies the objects present from a large dictionary of possible elements and operates reliably for real sound signals with multiple concurrently active sources. The key model assumption is that the activities of some cortical neurons encode the difference between the observed signal and an internal estimate. Reanalysis of awake auditory cortex recordings revealed neurons with patterns of activity corresponding to such an error signal.

Otazu, Gonzalo H.; Leibold, Christian

2011-01-01

161

An MOS transistor model for analog circuit design  

Microsoft Academic Search

This paper presents a physically based model for the metal-oxide-semiconductor (MOS) transistor suitable for analysis and design of analog integrated circuits. Static and dynamic characteristics of the MOS field-effect transistor are accurately described by single-piece functions of two saturation currents in all regions of operation. Simple expressions for the transconductance-to-current ratio, the drain-to-source saturation voltage, and the cutoff frequency in

A. I. A. Cunha; M. C. Schneider; C. Galup-Montoro

1998-01-01

162

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

163

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

164

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

165

Lightning Modelling: From 3D to Circuit Approach  

NASA Astrophysics Data System (ADS)

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 propose a simple equivalent electrical circuit to represent a geometrical structure, taking into account mutual, self inductances, and resistances, which play a fundamental role in the lightning current distribution. Then this model is intended to be coupled to a functional one, describing a power train chain composed of: a converter, a shielded power harness and a motor or a set of resistors used as a load for the converter. The novelty here, is to provide a pre-sizing qualitative approach allowing playing on integration in pre-design phases. This tool intends to offer a user-friendly way for replying rapidly to calls for tender, taking into account the lightning constraints. Two cases are analysed: first, a NLG that is composed of tubular pieces that can be easily approximated by equivalent cylindrical straight conductors. Therefore, passive R, L, M elements of the structure can be extracted through analytical engineer formulas such as those implemented in the partial element equivalent circuit (PEEC) [2] technique. Second, the same approach is intended to be applied on an electrical de-icing nacelle sub-system.

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

2012-05-01

166

Models for total dose degradation of linear integrated circuits  

SciTech Connect

Mechanisms for total dose degradation of linear circuits are discussed, including bulk effects, oxide charge buildup and recombination at the Si-SiO/sub 2/ interface. The dependence of damage on bias, dose, particle type and energy is used in conjunction with two-dimensional modeling to identify the failure mechanism in a specific linear device type. The importance of surface recombination is demonstrated along with the absence of bias dependence. Bulk damage is shown to be important for high energy electron irradiation because of wide-base pnp transistors. This causes substantial differences in device failure between electron and cobalt-60 environments that need to be taken into account for test standards and data bases that include commercial bipolar integrated circuits. Valid test methodologies for linear device must consider the energy and particle type present in the actual environment.

Johnston, A.H.; Plaag, R.E.

1987-12-01

167

Improved analytical model of the transverse coupling impedance of ferrite kicker magnets  

Microsoft Academic Search

A transformer model of ferrite kicker magnets is presented in this paper. Based on this model, an equivalent circuit is derived for which the elements can be obtained by bench measurements or by estimates from the magnet geometry. Improved formulas for the transverse coupling impedance of lumped and traveling wave kicker magnets are derived from the model and the equivalent

Daniele Davino; Harald Hahn

2003-01-01

168

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

169

Magnetization-noise-induced collapse and revival of Rabi oscillations in circuit QED  

NASA Astrophysics Data System (ADS)

We use a quasi-Hamiltonian formalism to describe the dissipative dynamics of a circuit-QED qubit that is affected by several fluctuating two-level systems with a 1/f-noise power spectrum. The qubit-resonator interactions are described by the Jaynes-Cummings model. We argue that the presence of pure dephasing noise in such a qubit-resonator system will also induce an energy relaxation mechanism via a fluctuating dipole-coupling term. This random modulation of the coupling is seen to lead to rich physical behavior. For non-Markovian noise, the coupling can either worsen or alleviate decoherence, depending on the initial conditions. The magnetization noise leads to behavior resembling the collapse and revival of Rabi oscillations if the photons are in a coherent state. For a broad distribution of noise couplings, the frequency of these oscillations depends on the mean noise strength. We describe this behavior semianalytically and find it to be independent of the number of fluctuators. This phenomenon could be used as an in situ probe of the noise characteristics.

De, Amrit; Joynt, Robert

2013-04-01

170

A lumped circuit model for transient arc discharges  

NASA Astrophysics Data System (ADS)

In this paper, arc discharges are modeled by a simple circuit involving the discharge of a capacitor through a series inductor and resistor. Four remarkable results are established for the arc discharge. Two of the results provide the threshold condition and finite final potential necessary for any realistic arc discharge theory, while another result suggests an experiment to look for a finite number of current oscillations in a highly driven arc. The final result suggests an experimental method for determining a constant which can model the usual phenomenological treatments of arc start and stop voltages, current ringing, and areal scaling.

Robiscoe, R. T.; Kadish, A.; Maier, William B., II

1988-11-01

171

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

2013-01-01

172

Multi physics multi scale modeling of microwave circuits and systems hybridizing circuit, electromagnetic and thermal modeling  

Microsoft Academic Search

Modeling of complex systems requires that a systematic approach be adopted for multi scale and multi physics modeling. The current state of physical modeling tools in the arena of microwave and electromagnetic model is considerably mature enabling discrete problems to be considered. The real need is for hybridization of discrete modeling systems to obtain a seamless simulation environment from atoms

Michael B. Steer

2004-01-01

173

Evaluation and Optimization of an Equivalent Model for Printed Circuit Boards inside Metallic Enclosures  

Microsoft Academic Search

An equivalent model of a printed circuit board can be useful for simplifying electromagnetic problems, reducing the computational cost of numerical simulations. In this paper an equivalent model of a printed circuit board inside a metallic enclosure is evaluated inversely by means of simulations and measurements. In order to achieve this goal, results for a set of different printed circuit

A. J. Lozano; M. P. Robinson; A. Díaz; J. V. Balbastre

174

[Setup of high voltage direct circuit equivalent circuit model in leakage detection of landfill].  

PubMed

An equivalent circuit model is put forward through analysis of the experiment data under the conditions of applying 400V, 350V and 300V DC supply power to a small-scale simulated landfill. Due to the fact that the existence of the HDPE geomembrane liner endows the model with commutating character, the electrolytic capacity increases as the area of geomembrane liner and the supplying electric voltage increase. The contact electric resistance of the power supply electrode is in direct proportion to earth electric resistance rate, and in relation to the diameter of the electrode and the depth of the earth. Moreover, the contact resistance is mainly determined by the earth electric resistance around the electrode (the influence induced by the earth farther than 10 times electrode radius is less than 10 percent of those involved by all resistance), hence decrease of the earth electric resistance rate around the electrode may result in effective decrease of the contact electric resistance of the electrode. PMID:15859438

Nai, Chang-xin; Wang, Yan-wen; Wang, Qi; Dong, Lu

2005-01-01

175

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

176

Modeling the Electrical Characteristics of the Global Electric Circuit  

NASA Astrophysics Data System (ADS)

Earth's global electric circuit (GEC) embodies the electrical pathways by which currents flow from electrified clouds to the ionosphere and return through fair weather regions to the earth's surface. To investigate this pathway, an analytic model based on others' previous work has been developed to produce global estimates of atmospheric currents, electric fields, and potential distributions of the GEC. The atmosphere between the ground and the ionosphere is composed of complex current sources and conductivity distributions. In the global electric circuit, lightning events act as current generators maintaining the potential difference between the earth and ionosphere. An analytic solution to Poisson's equation was applied to the GEC, allowing for a steady-state calculation of global distributions in potential, electric fields and currents for specified conductivity distributions and current sources. The global distribution of current sources provided on a monthly basis by a recently developed empirical model of Wilson currents. Analytic representations of global conductivities are implemented that include large-scale changes in the galactic cosmic ray flux. A novel numeric solver for Poisson's equation was also developed to enable analysis of more complex distributions of conductivity, i.e. cloud and aerosol effects. These models allow one to determine how different lightning and conductivity distributions impact the electrical characteristics of the GEC.

Lucas, G.; Lehto, E.; Baumgaertner, A. J.; Thayer, J. P.; Forbes, J. M.; Zhang, X.

2013-12-01

177

Ionospheric potential variability in global electric circuit models (Invited)  

NASA Astrophysics Data System (ADS)

The ionospheric potential (IP) represents the electric voltage between the Earth's surface and the lower ionosphere and may be measured with a sufficient accuracy using the balloon soundings over the lowest 15-20 km. This parameter can serve as a global index relating the state of the global electric circuit (GEC) to the planetary climate. Exploring the GEC as a diagnostic tool for climate studies requires an accurate modeling of the IP stationary state and its dynamics, while a question of secular trend of the IP is still under discussion (Markson, 2007; Williams, 2009; Williams and Mareev, 2013). This paper addresses a possibility of correct calculation of the IP in 3D models of the GEC and its adequate parameterization to be used in General Circulation Models (GCM). Our approach is based on the use the integral representation for the contribution of charging currents, supporting the generators (in particular, electrified clouds) in the GEC, into the ionospheric potential (Kalinin et al., 2011; Mareeva et al., 2011). Simple enough analytical expressions for IP induced by the charging electric currents are suggested, including the contribution of the Austausch generator. We have developed also the spherical numerical model of the GEC and applied it for IP calculation for different-type cloud contribution into the circuit. A suggested IP parameterization is appropriate for the use in climate-model simulations (Mareev and Volodin, 2011). We use a high-resolution GCM of the atmosphere and ocean INMCM4.0 for the modeling the GEC. The main characteristics of the model are: atmosphere - 2x1.5 degrees in longitude and latitude, 21 levels; ocean - 1x0.5 degrees in longitude and latitude, 40 levels. We have taken into account quasi-stationary currents of electrified clouds as principal contributors into the DC global circuit. One of the most important aspects of this approach is an account for all the electrified clouds- both thunderstorms and electrified shower cloud. The results have shown that many of the calculated parameters are consistent with measurements on the global circuit, in particular, the diurnal and seasonal variability of the GEC. We found that the inter-annual variability of the IP is low and does not exceed 1% from the mean value. It should be emphasized however that it is correlated tightly with the mean SST in the Pacific ocean (180W-100W, 5S-5N - El-Nigno area). As to long-term trend, mumerical simulations suggest the IP decrease by about 10% for the XXI century if the global warming follows an assumed greenhouse gas emission scenario RCP 8.5. It is interesting that, using Price&Rind parameterizations, it was found that a mean flash rate is increasing by about 20% for the century (from 60 to 72 fl/s) for the same scenario. We conclude that the use of GCM with respective IP parameterizations allows us to study the influence of different factors on the GEC state, including convection intensity and its trends in a warmer climate. Some generalizations of the modeling related to the conductivity perturbations should lead to better description of the electrical generators in the global circuit.

Mareev, E.; Volodin, E. M.; Kalinin, A.; Sllyunyaev, N.

2013-12-01

178

An effective dynamic coarse model for optimization design of LTCC RF circuits with aggressive space mapping  

Microsoft Academic Search

A new concept called the dynamic coarse model is proposed and is applied to the optimization design of low-temperature co-fired ceramic (LTCC) multilayer RF circuits with the aggressive space mapping (ASM) technique. The dynamic coarse model is a combination of an evolutionary equivalent-circuit model and an efficient quasi-static numerical electromagnetic (EM) model-partial-element equivalent-circuit model. Namely, there are two forms of

Ke-Li Wu; Yong-Jiu Zhao; Jie Wang; Michael K. K. Cheng

2004-01-01

179

Analysis of hybrid stepping motor using 3D equivalent magnetic circuit network method based on trapezoidal element  

NASA Astrophysics Data System (ADS)

The permanent magnet in a hybrid stepping motor (HSM) is magnetized in the axial direction. Accordingly, 2D analysis methods such as the 2D finite element method cannot guarantee accurate analysis. In this article, the characteristics of HSM are analyzed using the 3D equivalent magnetic circuit network method (3D EMCNM). The 3D EMCNM supplements the magnetic equivalent circuit by a numerical technique using distributed magnetic circuit parameters. Formerly, the 3D EMCNM based on the hexahedron element or the fan shaped element has usually been applied for linear motor analysis or rotary machine analysis. However, the use of these elements carries a serious permeance calculation error in complex shaped machinery such as a HSM. Therefore, to overcome this weakness, a new trapezoidal element is used.

Kim, Youn Hyun; Jin, Chang Sung; Kim, Sol; Chun, Yon Do; Lee, Ju

2002-05-01

180

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

181

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

PubMed

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 used in personal computers, were studied in order to recover the metals in the circuit boards through mechanical processing, such as crushing, screening, as well as magnetic and electrostatic separation. The results obtained demonstrate the feasibility of using these processes to separate metal fractions from polymers and ceramics, and that it is possible to obtain a fraction concentrated in metals containing more than 50% on average of copper, 24% of tin and 8% of lead. PMID:15681180

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

2005-01-01

182

The use of SPICE lumped circuits as sub-grid models for FDTD analysis  

Microsoft Academic Search

A general approach for including lumped circuit elements in a finite difference time domain (FDTD) solution of Maxwell's equations is presented. The methodology allows the direct access to SPICE to model the lumped circuits, while the full 3-dimensional solution to Maxwell's equations provides the crosstalk and dispersive properties of the microstrips and striplines in the circuit

Vincent A. Thomas; Michael E. Jones; Melinda Piket-May; Allen Taflove; Evans Harrigan

1994-01-01

183

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

184

Embedded Micro-Flux-Gate Magnetic Sensor in Printed Circuit Board  

NASA Astrophysics Data System (ADS)

We have developed a micro-flux-gate magnetic sensor using a new printed circuit board (PCB) technology. The flux-gate sensor consists of five PCB stack layers including one layer of magnetic core and four layers of excitation and pickup coils. The center layer as a magnetic core is made of a micropatterned amorphous magnetic ribbon with an extremely high DC permeability of ˜100{,}000; the core has a rectangular ring shape. The four outer layers as excitation and pickup coils have a planar solenoid structure. The amorphous magnetic core is easily saturated due to the low coercive field and closed magnetic path of the excitation field. The chip size of the fabricated sensing element is 9.8 × 5.7 mm2. Excellent linear response over the range of -100 to +100 ?T is obtained with 1460 V/T sensitivity at an excitation sine wave of 3 Vp-p and 360 kHz. A low power consumption of ˜10 mW was measured.

Choi, Won-Youl; Hwang, Jun-Sik; Choi, Sang-On

2005-08-01

185

Interplanetary magnetic field and atmospheric electric circuit influences on ground-level pressure at Vostok  

NASA Astrophysics Data System (ADS)

The Mansurov effect, which for the Southern Hemisphere consists of a positive association between the By component (east-west) of the interplanetary magnetic field (IMF) and the ground-level pressure for stations poleward of ~80° magnetic latitude, is confirmed for Vostok (78.5°S, 106.9°E magnetic latitude 83.6°S) using modern data. The magnitude of the association is small (0.19 hP per nT; 1.2% common covariance) but statistically significant (at the 96.1% level). A more substantial association exists, with a slight delay (2-3 days) and a cumulative influence, between the Vostok station pressure and the local vertical electric field, a proxy for the air-Earth current Jz. A composite series constructed as a weighted sum of vertical electric field values at lags between 1 and 4 days yields a linear regression gradient with respect to Vostok station-level pressure of 0.10 hP per Vm-1, 10.0% common covariance and is statistically significant at the 99.9% level. We confirm a previously reported Sun-weather linkage (the Mansurov effect), provide evidence that the mechanism operates via the atmospheric electric circuit and present data supporting an inferred and more substantial surface pressure response to changes in the global atmospheric circuit.

Burns, G. B.; Tinsley, B. A.; Frank-Kamenetsky, A. V.; Bering, E. A.

2007-02-01

186

Model a Magnet  

NSDL National Science Digital Library

This is a summative activity about magnets. Learners will observe a demonstration of the action of a magnet on a test tube of iron filings, answer questions, and, using the concepts learned in previous activities, write an essay about their understanding of the demonstration. This is the fourth activity in the Mapping Magnetic Influence educators guide. Learners should complete the other three activities in that guide (Seeing Magnetism, What Do You Know about Magnets, and Magnet Map) prior to beginning this activity.

187

Lumped-circuit model of four-vane RFQ resonator  

SciTech Connect

Although the rf cavity code SUPERFISH is a necessary tool for designing rf cavities, it is often useful to have approximate analytic formulas for the electromagnetic properties of a cavity. One approach for the RFQ four-vane cavity is to use the analtytic solutions associated with an inclined plane waveguide. The large capacitive vane loading in the four-vane RFQ resonator allows a convenient representation by a simple lumped-circuit model. Formulas are derived that depend on a single unknown parameter: the vane capacitance per unit length, which can be calculated for different vane geometries using SUPERFISH. The formulas from the model are useful for estimating the RFQ's electromagnetic properties as a function of parameters such as frequency and intervane voltage.

Wangler, T.P.

1984-01-01

188

Astrocyte regulation of sleep circuits: experimental and modeling perspectives  

PubMed Central

Integrated within neural circuits, astrocytes have recently been shown to modulate brain rhythms thought to mediate sleep function. Experimental evidence suggests that local impact of astrocytes on single synapses translates into global modulation of neuronal networks and behavior. We discuss these findings in the context of current conceptual models of sleep generation and function, each of which have historically focused on neural mechanisms. We highlight the implications and the challenges introduced by these results from a conceptual and computational perspective. We further provide modeling directions on how these data might extend our knowledge of astrocytic properties and sleep function. Given our evolving understanding of how local cellular activities during sleep lead to functional outcomes for the brain, further mechanistic and theoretical understanding of astrocytic contribution to these dynamics will undoubtedly be of great basic and translational benefit.

Fellin, Tommaso; Ellenbogen, Jeffery M.; De Pitta, Maurizio; Ben-Jacob, Eshel; Halassa, Michael M.

2012-01-01

189

3D line current model of coils and external circuits  

Microsoft Academic Search

The paper describes a method of three dimensional magnetic field simulation with finite elements including the eddy current problem of coils that are coupled with an electric network. The coupled problem is treated in a time stepping scheme. The electric coils are represented in a mesh-independent fashion by the line current model. The equations from a nodal analysis of the

Thomas Dreher; GCrard Meunier

1995-01-01

190

Circuit Modeling of the Electrical Impedance Part I: Neuromuscular Disease  

PubMed Central

Multifrequency electrical impedance myography (MFEIM) in the 3 to 300 kHz range was applied to 68 subjects representing 19 different neuromuscular diseases, and the impedances analyzed using the 5-element circuit model. Depending on severity, the “cellular” parameters r2, r3, 1/c1 and 1/c2 were found to be as much as 10 to 20 fold larger than for normal subjects (taking age and girth into account), but in almost every case the extracellular fluid parameter r1 was at most only marginally affected. Strong correlations are found between r2 and 1/c1, but in the case of ALS that breaks down when c1 (representing the muscle fibre membrane capacitance) falls below half the normal value. Also, c2 (tentatively associated with intracellular organelle membranes) was found to be the most sensitive to disease progress in ALS, about 3 times more so than the 50 kHz phase, already suggested for use in clinical drug testing. We conclude that following parameters obtained using the combined MFEIM/5-element circuit analysis scheme offers a reliable, non-invasive and objective way of characterizing muscle in neuromuscular disease or during clinical drug testing.

Shiffman, C A; Rutkove, S B

2013-01-01

191

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

192

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

193

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

194

Time-Dependent Model of the Global Electric Circuit  

NASA Astrophysics Data System (ADS)

The Global Electric Circuit (GEC) is a circuit that is formed between the Earth's surface, which is a good conductor of electricity, and the ionosphere, a weekly-ionized plasma at around 80 km altitude [e.g., Rycroft et al., Space Sci. Rev., 137(1-4), pp. 83-105, 2008]. In the absence of any source, the GEC behaves as a leaky spherical capacitor, with the ground being the negative charged plate and the ionosphere the positive one, which discharges through the weakly conducting atmosphere creating fair-weather current, which is about 1 kA integrated over the entire Earth surface [e.g., Bering et al., Physics Today, Oct., 24-30, 1998]. It is accepted that thunderstorms are the main generators in the GEC [e.g., Williams, Atmospheric Research, 91, 140, 2009; Mareev, Physics Uspekhi, 53, 504, 2010]. In this current work, we developed a two-dimensional cylindrical time-dependent model, which calculates the quasi-electrostatic fields created by the slow accumulation of the charge in the cloud, by taking into account the Maxwellian relaxation of the charges in the conducting atmosphere. The model is capable of simulating the whole volume of the GEC and thus it has the same electrical properties as the three-dimensional spherical system. Two different kinds of boundary conditions (Dirichlet and homogeneous Neumann boundary conditions) were used in order to describe the global circulation of the current, and it has been found that both of them give the same results regarding the general contribution of a storm to the GEC. We present results regarding the response of the fair weather region to lightning transients that occur in the thunderstorm, and in the steady state limit the results of the time-dependent model are compared to static GEC solutions similar to those reported previously by Tzur and Roble [JGR, 90, 5989, 1985].

Mallios, S. A.; Pasko, V. P.

2013-12-01

195

Accurate parametric modeling of folded waveguide circuits for millimeter-wave traveling wave tubes  

Microsoft Academic Search

In this paper, results of different models are compared for calculating effective, cold-circuit (beam-free) phase velocities and interaction impedances of folded waveguide (FW) slow wave circuits for use in millimeter-wave traveling wave tubes (TWT). These parameters are needed for one-dimensional (1-D) parametric model simulations of FW traveling wave tubes (FWTWTs). The models investigated include approximate analytic expressions, equivalent circuit, three-dimensional

John H. Booske; Mark C. Converse; Carol L. Kory; Christine T. Chevalier; David A. Gallagher; Kenneth E. Kreischer; Vernon O. Heinen; Sudeep Bhattacharjee

2005-01-01

196

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

197

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

198

Modelling and design for PM/EM magnetic bearings  

NASA Technical Reports Server (NTRS)

A mathematical model of a permanent magnet/electromagnet (PM/EM) radially active bearing is presented. The bearing is represented by both a reluctance model and a stiffness model. The reluctance model analyzes the magnetic circuit of the PM/EM bearings. By combining the two models, the performance of the bearing can be predicted given geometric dimensions, permanent magnet strength, and the parameters of the EM coils. The overall bearing design including the PM and EM design is subject to the performance requirement and physical constraints. A study of these requirements and constraints is discussed. The PM design is based on the required magnetic flux for proper geometric dimensions and magnet strength. The EM design is based on the stability and force slew rate consideration, and dictates the number of turns for the EM coils and the voltage and current of the power amplifier. An overall PM/EM bearing design methodology is proposed and a case study is also demonstrated.

Pang, D.; Kirk, J. A.; Anand, D. K.; Johnson, R. G.; Zmood, R. B.

1992-01-01

199

A magnetic hysteresis model  

NASA Technical Reports Server (NTRS)

The Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS) will be deployed from the Space Shuttle and used as a target for a Shuttle-mounted laser. It will be a cylindrical satellite with several corner cube reflectors on the ends. The center of mass of the cylinder will be near one end, and aerodynamic torques will tend to align the axis of the cylinder with the spacecraft velocity vector. Magnetic hysteresis rods will be used to provide passive despin and oscillation-damping torques on the cylinder. The behavior of the hysteresis rods depends critically on the 'B/H' curves for the combination of materials and rod length-to-diameter ratio ('l-over-d'). These curves are qualitatively described in most Physics textbooks in terms of major and minor 'hysteresis loops'. Mathematical modeling of the functional relationship between B and H is very difficult. In this paper, the physics involved is not addressed, but an algorithm is developed which provides a close approximation to empirically determined data with a few simple equations suitable for use in computer simulations.

Flatley, Thomas W.; Henretty, Debra A.

1995-01-01

200

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

2012-09-01

201

Experiments on evolving software models of analog circuits  

Microsoft Academic Search

sed and experimented with a new encodingsystem that consists of a sequence of circuit-constructinginstructions. Like the "turtle" in the languageLogo that can be commanded to draw animage, our language uses an automaton programmedto construct an electrical circuit. Theautomaton is called a circuit-constructing robot orcc-bot, and the language that programs it is verysmall and, in its current incarnation, contains onlycomponent-placing instructions.

Jason D. Lohn

1999-01-01

202

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

203

Analysis of an HID-lamp igniter using a two-stage magnetic-pulse-compression circuit  

Microsoft Academic Search

This paper proposes a high-intensity-discharge (HID) lamp igniter using a two-stage magnetic-pulse-compression (MPC) circuit. The circuit operation is analyzed and an optimal design procedure for selecting the saturable reactors and energy storage capacitors is derived. Experimental verification is also given. This igniter can generate voltage pulses whose peak value and pulse width are 50 kV and 800 ns, respectively

H. Kakehashil; M. Habu; T. Ninomiya; M. Shoyama; H. Ogasawara; Y. Ohta

1998-01-01

204

Simulations of magnetic field gradients due to micro-magnets on a triple quantum dot circuit  

NASA Astrophysics Data System (ADS)

To quantify the effects of local magnetic fields on triple quantum dots, the Heisenberg Hamiltonian has been diagonalized for three electrons coupled via the exchange interaction. In particular, we have investigated different geometries of micro-magnets located on top of the triple dot in order to optimize the field gradient characteristics. In this paper, we focus on two geometries which are candidates for an addressable EDSR triple quantum dot device.

Poulin-Lamarre, G.; Bureau-Oxton, C.; Kam, A.; Zawadzki, P.; Studenikin, S.; Aers, G.; Pioro-Ladrière, M.; Sachrajda, A. S.

2013-12-01

205

?-? circuit-breaker arc modelling around current zero: II. Arc-circuit-interaction simulation using Boltzmann analysis  

NASA Astrophysics Data System (ADS)

This paper reports the initial results of a complete physico-chemical modelling of a 0022-3727/32/4/019/img9 circuit-breaker arc. The time-dependent results of a collisional-radiative model combined with Boltzmann analysis to determine the electron transport properties in a uniform zero-dimensional space are given. Microscopic processes leading to extinction of the 0022-3727/32/4/019/img9 arc under the influence of the electrical circuit are evaluated and discussed. It is shown that, under some conditions the electron temperature is elevated considerable over the gas temperature driven by the electrical field strength inherently built up by arc-circuit interaction after current zero. The related electron-impact, recombination and association processes, which are decisive for the failure or success of the current interruption by the circuit breaker, are studied in detail. Whereas 0022-3727/32/4/019/img11 exhibits entirely favourable physico-chemical properties for current interruption, nitrogen requires additional cooling by a mechanical blast because of a combination of highly exothermic association reactions, inefficient electron removal and efficient ionization of atomic nitrogen.

Cliteur, G. J.; Suzuki, K.; Paul, K. C.; Sakuta, T.

1999-02-01

206

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

207

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

208

Modeling the dynamical effects of anesthesia on brain circuits.  

PubMed

General anesthesia is a neurophysiological state that consists of unconsciousness, amnesia, analgesia, and immobility along with maintenance of physiological stability. General anesthesia has been used in the United States for more than 167 years. Now, using systems neuroscience paradigms how anesthetics act in the brain and central nervous system to create the states of general anesthesia is being understood. Propofol is one of the most widely used and the most widely studied anesthetics. When administered for general anesthesia or sedation, the electroencephalogram (EEG) under propofol shows highly structured, rhythmic activity that is strongly associated with changes in the patient's level of arousal. These highly structured oscillations lend themselves readily to mathematical descriptions using dynamical systems models. We review recent model descriptions of the commonly observed EEG patterns associated with propofol: paradoxical excitation, strong frontal alpha oscillations, anteriorization and burst suppression. Our analysis suggests that propofol's actions at GABAergic networks in the cortex, thalamus and brainstem induce profound brain dynamics that are one of the likely mechanisms through which this anesthetic induces altered arousal states from sedation to unconsciousness. Because these dynamical effects are readily observed in the EEG, the mathematical descriptions of how propofol's EEG signatures relate to its mechanisms of action in neural circuits provide anesthesiologists with a neurophysiologically based approach to monitoring the brain states of patients receiving anesthesia care. PMID:24457211

Ching, Shinung; Brown, Emery N

2014-04-01

209

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

210

A Computational Model of Gene Expression in an Inducible Synthetic Circuit  

Microsoft Academic Search

Synthetic biology aims to the rational design of gene circuits with predictable behaviours. Great efforts have been done so far to introduce in the field mathematical models that could facilitate the design of synthetic networks. Here we present a mathematical model of a synthetic gene-circuit with a negative feedback. The closed loop configuration allows the control of transcription by an

Francesca Ceroni; Simone Furini; Silvio Cavalcanti

2010-01-01

211

Optimization of the Titania Humidity Sensor Equivalent Circuit Model Based on Genetic Algorithms  

Microsoft Academic Search

Taking the parameters of the Titania humidity sensor equivalent circuit model as an optimizing object, this paper proposes an optimization model to improve equivalent circuits based on genetic algorithms. Elitist strategy is added into the selection option of the algorithms, and fitness function is suitably adjusted. Thus, the operating efficiency and accuracy of the algorithms are enhanced, and a fitting

Gang Liu; Xingcheng Wang; Kai Zheng; Ming Yang

2011-01-01

212

Extra high speed modified Lundell alternator parameters and open/short-circuit characteristics from global 3D-FE magnetic field solutions  

NASA Technical Reports Server (NTRS)

The combined magnetic vector potential - magnetic scalar potential method of computation of 3D magnetic fields by finite elements, introduced in a companion paper, is used for global 3D field analysis and machine performance computations under open-circuit and short-circuit conditions for an example 14.3 kVA modified Lundell alternator, whose magnetic field is of intrinsic 3D nature. The computed voltages and currents under these machine test conditions were verified and found to be in very good agreement with corresponding test data. Results of use of this modelling and computation method in the study of a design alteration example, in which the stator stack length of the example alternator is stretched in order to increase voltage and volt-ampere rating, are given here. These results demonstrate the inadequacy of conventional 2D-based design concepts and the imperative of use of this type of 3D magnetic field modelling in the design and investigation of such machines.

Wang, R.; Demerdash, N. A.

1992-01-01

213

Basic neuron model electrical equivalent circuit: an undergraduate laboratory exercise.  

PubMed

We developed a hands-on laboratory exercise for undergraduate students in which they can build and manipulate a neuron equivalent circuit. This exercise uses electrical circuit components that resemble neuron components and are easy to construct. We describe the methods for creating the equivalent circuit and how to observe different neuron properties through altering the structure of the equivalent circuit. We explain how this hands-on laboratory activity allows for the better understanding of this fundamental neuroscience concept. At the conclusion of this laboratory exercise, undergraduate students will be able to apply the principles of Ohm's law, cable theory with regards to neurons, and understand the functions of resistance and capacitance in a neuron. PMID:24319391

Dabrowski, Katie M; Castaño, Diego J; Tartar, Jaime L

2013-01-01

214

Modeling the corrosion behaviors of the heat transport circuits of light water nuclear reactors.  

National Technical Information Service (NTIS)

To model the corrosion behaviors of the heat transport circuits of light water reactors, a mixed potential model (MPM) has been developed and applied to both boiling water reactors (BWRS) and pressurized water reactors (PWRs). Using the data generated by ...

A. Bertuch D. D. Macdonald J. Pang L. Kriksunov K. Arioka

1993-01-01

215

Proposal of Switched-mode Matching Circuit in power supply for wireless power transfer using magnetic resonance coupling  

Microsoft Academic Search

This paper discusses on the matching circuit in the power supply for wireless power transfer using a magnetic resonance coupling (MRC). The MRC is desired to operate at high frequency in the Industry Science Medical (ISM) bands such as 13.56 MHz. The resonance with high quality factor between the transmitting side and receiving side enables high efficiency for wireless power

Keisuke Kusaka; Jun-ichi Itoh

2012-01-01

216

[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

217

Including Internal Losses In The Equivalent Circuit Model Of The SLAC Damped Detuned Structure (DDS)  

SciTech Connect

In the equivalent circuit model for the DDS originally presented no losses were explicitly included in the cell circuits or the manifold circuits. Damping via the manifolds was effected by imposing matching conditions (including the possibility of reflection) on the ends of the manifolds. In this paper we extend the circuit theory to include lossy circuit elements. We discuss and compare shunt conductance and series resistance models for the cells. Manifold damping is modeled by introducing a shunt conductance per unit length in the transmission line elements of the manifolds. We apply the theory to the mitigation of performance degradation associated with fabricationally desirable decoupling of several cells at the ends of the structure from the manifolds.

Jones, Roger M

1999-04-01

218

Efficient DDD-based term generation algorithm for analog circuit behavioral modeling  

Microsoft Academic Search

An efficient approach to generating symbolic product terms for behavioral modeling of large linear analog circuits is presented. The approach is based on a compact determinant decision diagram (DDD) representation of transfer functions and characteristics of analog circuits. The new algorithm is based on the concept that a dominant term in a DDD graph can be found by searching the

S. X.-D. Tan; C.-J. R. Shi

2003-01-01

219

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

220

Process Dependent Electrical Characteristics and Equivalent Circuit Model of SOL-GEL Based PZT Capacitors.  

National Technical Information Service (NTIS)

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 cap...

T. Mihara H. Watanabe H. Yoshimori C. A. Paz De Araujo

1991-01-01

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

Equivalent-circuit model of the squeezed gas film in a silicon accelerometer  

Microsoft Academic Search

We present a new electric equivalent circuit for the forces created by a squeezed gas film between vertically moving planar surfaces. The model is realized with frequency-dependent resistors and inductors. Circuit analysis tools are applied to calculate the response of a micromechanical silicon capacitive accelerometer in both the frequency and the time domains. The simulations are shown to match the

Timo Veijola; Heikki Kuisma; Juha Lahdenperä; Tapani Ryhänen

1995-01-01

223

GABAergic circuit dysfunction in the Drosophila Fragile X syndrome model.  

PubMed

Fragile X syndrome (FXS), caused by loss of FMR1 gene function, is the most common heritable cause of intellectual disability and autism spectrum disorders. The FMR1 protein (FMRP) translational regulator mediates activity-dependent control of synapses. In addition to the metabotropic glutamate receptor (mGluR) hyperexcitation FXS theory, the GABA theory postulates that hypoinhibition is causative for disease state symptoms. Here, we use the Drosophila FXS model to assay central brain GABAergic circuitry, especially within the Mushroom Body (MB) learning center. All 3 GABAA receptor (GABAAR) subunits are reportedly downregulated in dfmr1 null brains. We demonstrate parallel downregulation of glutamic acid decarboxylase (GAD), the rate-limiting GABA synthesis enzyme, although GABAergic cell numbers appear unaffected. Mosaic analysis with a repressible cell marker (MARCM) single-cell clonal studies show that dfmr1 null GABAergic neurons innervating the MB calyx display altered architectural development, with early underdevelopment followed by later overelaboration. In addition, a new class of extra-calyx terminating GABAergic neurons is shown to include MB intrinsic ?/? Kenyon Cells (KCs), revealing a novel level of MB inhibitory regulation. Functionally, dfmr1 null GABAergic neurons exhibit elevated calcium signaling and altered kinetics in response to acute depolarization. To test the role of these GABAergic changes, we attempted to pharmacologically restore GABAergic signaling and assay effects on the compromised MB-dependent olfactory learning in dfmr1 mutants, but found no improvement. Our results show that GABAergic circuit structure and function are impaired in the FXS disease state, but that correction of hypoinhibition alone is not sufficient to rescue a behavioral learning impairment. PMID:24423648

Gatto, Cheryl L; Pereira, Daniel; Broadie, Kendal

2014-05-01

224

An in-depth noise model for giant magnetoresistance current sensors for circuit design and complementary metal-oxide-semiconductor integration  

NASA Astrophysics Data System (ADS)

Full instrumentation bridges based on spin valve of giant magnetoresistance and magnetic tunnel junction devices have been microfabricated and experimentally characterized from the DC and noise viewpoint. A more realistic model of these devices was obtained in this work, an electrical and thermal model previously developed have been improved in such a way that noise effects are also included. We have implemented the model in a circuit simulator and reproduced the experimental measurements accurately. This provides a more realistic and complete tool for circuit design where magnetoresistive elements are combined with well-known complementary metal-oxide-semiconductor modules.

Roldán, A.; Roldán, J. B.; Reig, C.; Cardoso, S.; Cardoso, F.; Ferreira, R.; Freitas, P. P.

2014-05-01

225

A Circuit-Compatible SPICE model for Enhancement Mode Carbon Nanotube Field Effect Transistors  

Microsoft Academic Search

This paper presents a circuit-compatible compact model for short channel length (5 nm~100 nm), quasi-ballistic single wall carbon nanotube field-effect transistors (CNFETs). For the first time, a universal circuit-compatible CNFET model was implemented with HSPICE. This model includes practical device non-idealities, e.g. the quantum confinement effects in both circumferential and channel length direction, the acoustical\\/optical phonon scattering in channel region

J. Deng; H.-S. P. Wong

2006-01-01

226

Changing and shielded magnetic fields suppress c-Fos expression in the navigation circuit: input from the magnetosensory system contributes to the internal representation of space in a subterranean rodent  

PubMed Central

The neural substrate subserving magnetoreception and magnetic orientation in mammals is largely unknown. Previous experiments have demonstrated that the processing of magnetic sensory information takes place in the superior colliculus. Here, the effects of magnetic field conditions on neuronal activity in the rodent navigation circuit were assessed by quantifying c-Fos expression. Ansell's mole-rats (Fukomys anselli), a mammalian model to study the mechanisms of magnetic compass orientation, were subjected to natural, periodically changing, and shielded magnetic fields while exploring an unfamiliar circular arena. In the undisturbed local geomagnetic field, the exploration of the novel environment and/or nesting behaviour induced c-Fos expression throughout the head direction system and the entorhinal–hippocampal spatial representation system. This induction was significantly suppressed by exposure to periodically changing and/or shielded magnetic fields; discrete decreases in c-Fos were seen in the dorsal tegmental nucleus, the anterodorsal and the laterodorsal thalamic nuclei, the postsubiculum, the retrosplenial and entorhinal cortices, and the hippocampus. Moreover, in inactive animals, magnetic field intensity manipulation suppressed c-Fos expression in the CA1 and CA3 fields of the hippocampus and the dorsal subiculum, but induced expression in the polymorph layer of the dentate gyrus. These findings suggest that key constituents of the rodent navigation circuit contain populations of neurons responsive to magnetic stimuli. Thus, magnetic information may be integrated with multimodal sensory and motor information into a common spatial representation of allocentric space within this circuit.

Burger, Tomas; Lucova, Marcela; Moritz, Regina E.; Oelschlager, Helmut H. A.; Druga, Rastislav; Burda, Hynek; Wiltschko, Wolfgang; Wiltschko, Roswitha; Nemec, Pavel

2010-01-01

227

Magnetic Hysteresis Model.  

National Technical Information Service (NTIS)

The Passive Aerodynamically Stabilized Magnetically Damped Satellite (PAMS) will be deployed from the Space Shuttle and used as a target for a Shuttle-mounted laser. It will be a cylindrical satellite with several corner cube reflectors on the ends. The c...

T. W. Flatley D. A. Henretty

1995-01-01

228

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

229

Representing circuits more efficiently in symbolic model checking  

Microsoft Academic Search

We significantly reduce the complexity of BDD-based symbolic verification by using partitioned transition relations to represent state transition graphs. On an example pipeline circuit, this technique reduced the verification time by an order of magnitude and the storage requirements for the transition relation by two orders of magnitude. We were also able to handle example pipelines with over 10120 reachable

Jerry R. Burch; Edmund M. Clarke; David E. Long

1991-01-01

230

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

231

Microwave Resonator Circuit Model from Measured Data Fitting  

Microsoft Academic Search

An iterative procedure is developed for least squares estimation, from measured impedance data, of the parameters specifying a lumped-element resonant circuit equivalent to a dielectric resonator single resonance. The procedure is applicable to large sets of measured data obtained by an automatic network analyzer.

W. P. Wheless; Darko Kajfez

1986-01-01

232

Modeling and Fabrication of Micro FET Pressure Sensor with Circuits  

PubMed Central

This paper presents the simulation, fabrication and characterization of a micro FET (field effect transistor) pressure sensor with readout circuits. The pressure sensor includes 16 sensing cells in parallel. Each sensing cell that is circular shape is composed of an MOS (metal oxide semiconductor) and a suspended membrane, which the suspended membrane is the movable gate of the MOS. The CoventorWare is used to simulate the behaviors of the pressure sensor, and the HSPICE is employed to evaluate the characteristics of the circuits. The pressure sensor integrated with circuits is manufactured using the commercial 0.35 ?m CMOS (complementary metal oxide semiconductor) process and a post-process. In order to obtain the suspended membranes, the pressure sensor requires a post-CMOS process. The post-process adopts etchants to etch the sacrificial layers in the pressure sensors to release the suspended membranes, and then the etch holes in the pressure sensor are sealed by LPCVD (low pressure chemical vapor deposition) parylene. The pressure sensor produces a change in current when applying a pressure to the sensing cells. The circuits are utilized to convert the current variation of the pressure sensor into the voltage output. Experimental results show that the pressure sensor has a sensitivity of 0.032 mV/kPa in the pressure range of 0-500 kPa.

Dai, Ching-Liang; Tai, Yao-Wei; Kao, Pin-Hsu

2007-01-01

233

Modeling, design and control of a 30 hp permanent magnet synchronous motor  

Microsoft Academic Search

In this thesis, aspects of modeling, design and control of permanent magnet synchronous motors (PMSMs) are studied. An improved analytical model with stator winding space harmonics included is derived, based on generalized electrical machine theory. Neglecting the space harmonics leads to a simplified d-q equivalent circuit model. These analytical models allow the terminal quantities of a PMSM to be determined.

1991-01-01

234

Modeling of end-effect in flux-switching permanent magnet machines  

Microsoft Academic Search

A lumped parameter magnetic circuit model is employed to predict the influence of the finite length of a flux- switching permanent magnet machine on the electromagnetic torque. It enables performance predictions from 2-D finite element analysis to be used to analyze the electromagnetic performance with due account of end-effects. A simplified method for determining the ratio of actual torque to

Z. Q. Zhu; J. T. Chen; Y. Pang; D. Howe; S. Iwasaki; R. Deodhar

2007-01-01

235

Modeling and simulation of magnetizing inrush current of large power transformers  

Microsoft Academic Search

This paper presents a model for simulating magnetizing inrush current in large power transformer. The voltage and current distribution in the transformer winding under energisation conditions is formulated on the basis that the magnetic field can be considered as the composition of main flux in the iron core and leakage flux in the coil space. The calculation of the circuit

Li Donoxia; Wang Zanji; Liu Xiucheng

2001-01-01

236

A study of the various phases of the break in a low-voltage circuit breaker thanks to the magnetic camera  

NASA Astrophysics Data System (ADS)

By analysing the magnetic induction created by the arc motion from the outside of a breaking system at numerous points, it is possible to determine the position of the average line of current that magnetically represents the arc. This method is called the `magnetic camera' method. It had to be adapted to the circuit breaker studied here. Thanks to the method three phases of the course of the electrical arc are highlighted for a typical experiment: expansion of the arc, commutation from the mobile contact onto the lower rail and displacement through the splitter plates. In order to be more precise about the duration of the commutation phase, during which more than a single line of current must exist, an improved model of the arc motion has been developed.

Cajal, D.; Laurent, A.; Gary, F.; Mercier, M.; Servant, S.

1999-05-01

237

Quantum game simulator, using the circuit model of quantum computation  

NASA Astrophysics Data System (ADS)

We present a general two-player quantum game simulator that can simulate any two-player quantum game described by a 2×2 payoff matrix (two strategy games).The user can determine the payoff matrices for both players, their strategies and the amount of entanglement between their initial strategies. The outputs of the simulator are the expected payoffs of each player as a function of the other player's strategy parameters and the amount of entanglement. The simulator also produces contour plots that divide the strategy spaces of the game in regions in which players can get larger payoffs if they choose to use a quantum strategy against any classical one. We also apply the simulator to two well-known quantum games, the Battle of Sexes and the Chicken game. Program summaryProgram title: Quantum Game Simulator (QGS) Catalogue identifier: AEED_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEED_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3416 No. of bytes in distributed program, including test data, etc.: 583 553 Distribution format: tar.gz Programming language: Matlab R2008a (C) Computer: Any computer that can sufficiently run Matlab R2008a Operating system: Any system that can sufficiently run Matlab R2008a Classification: 4.15 Nature of problem: Simulation of two player quantum games described by a payoff matrix. Solution method: The program calculates the matrices that comprise the Eisert setup for quantum games based on the quantum circuit model. There are 5 parameters that can be altered. We define 3 of them as constant. We play the quantum game for all possible values for the other 2 parameters and store the results in a matrix. Unusual features: The software provides an easy way of simulating any two-player quantum games. Running time: Approximately 0.4 sec (Region Feature) and 0.3 sec (Payoff Feature) on a Intel Core 2 Duo GHz with 2 GB of memory under Windows XP.

Vlachos, Panagiotis; Karafyllidis, Ioannis G.

2009-10-01

238

Physics Based Lumped Element Circuit Model for Nanosecond Pulsed Dielectric Barrier Discharges.  

National Technical Information Service (NTIS)

This work presents a physics based circuit model for calculating the total energy dissipated into neutral species for nanosecond pulsed direct current (DC) dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that ...

B. Glaz S. Roy T. Underwood

2013-01-01

239

Development of a Lumped Element Circuit Model for Approximation of Nanosecond Pulsed Dielectric Barrier Discharges.  

National Technical Information Service (NTIS)

This work presents a circuit model for calculating the total energy dissipated into neutral species for nanosecond pulsed direct current (DC) dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that the nanosecond...

B. Glaz S. Roy T. C. Underwood

2013-01-01

240

Development of a Lumped Element Circuit Model for Approximation of Dielectric Barrier Discharges.  

National Technical Information Service (NTIS)

This work presents a circuit model for calculating the total energy dissipated into neutral species for pulsed direct current (DC) dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that nanosecond pulsed DBDs, w...

T. C. Underwood

2011-01-01

241

The development of dynamic models for a dense medium separation circuit in coal beneficiation  

Microsoft Academic Search

Often the most difficult step in establishing a control system is the development of a suitable dynamic process model. As such a model is not available elsewhere, a first principle dynamic mathematical model was developed for a coal dense medium separation circuit. Each unit operation was modelled individually and then integrated together to form a complete non-linear state–space model for

E. J. Meyer; I. K. Craig

2010-01-01

242

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

243

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

244

A coupled-circuit model for a DFIG operating under unbalanced conditions  

Microsoft Academic Search

The paper describes a time-stepped coupled-circuit model for a doubly-fed induction generator. The model, which is based on the summation of the harmonic winding inductances, is capable of representing both open- and short-circuit stator and rotor winding faults. The main purpose of this paper is to present evidence of the validity of this versatile and powerful technique and the advantages

S. Djurovic; S. Williamson

2008-01-01

245

Compact modeling of vertical ESD protection NPN transistors for RF circuits  

Microsoft Academic Search

We present an easy-to-use, simulator-independent compact model of a vertical npn transistor suitable for ESD circuit simulation. In addition to including high-current and breakdown effects, we also model accurately the small-signal off-state impedance of the device using s-parameter measurements, for inclusion in RF circuit simulations. Experimental results are provided for silicon and SiGe npn transistors.

Sopan Joshi; Elyse Rosenbaum

2002-01-01

246

A proper model for the partitioning of electrical circuits  

Microsoft Academic Search

Partitioning algorithms for electrical circuits are often based on the heuristic manipulation of a simple element-to-element interconnection matrix. However, the element-to-element interconnection matrix does not properly represent an electrical interconnection, or “net”, among more than two elements. This paper expands on several aspects of the discrepancy: 1) its source, 2) the circumstances under which it is likely to be significant,

D. G. Schweikert; B. W. Kernighan

1972-01-01

247

Generalized equivalent circuit model for ultra wideband antenna structure with double steps for energy scavenging  

NASA Astrophysics Data System (ADS)

There are various types of UWB antennas can be used to scavenge energy from the air and one of them is the printed disc monopole antenna. One of the new challenges imposed on ultra wideband is the design of a generalized antenna circuit model. It is developed in order to extract the inductance and capacitance values of the UWB antennas. In this research work, the developed circuit model can be used to represent the rectangular printed disc monopole antenna with double steps. The antenna structure is simulated with CST Microwave Studio, while the circuit model is simulated with AWR Microwave Office. In order to ensure the simulation result from the circuit model is accurate, the circuit model is also simulated using Mathlab program. The developed circuit model is found to be able to depict the actual UWB antenna. Energy harvesting from environmental wirelessly is an emerging method, which forms a promising alternative to existing energy scavenging system. The developed UWB can be used to scavenge wideband energy from electromagnetic wave present in the environment.

>Oon Kheng Heong, Goh Chin; Chakrabarty, Chandan Kumar; >Goh Tian Hock,

2013-06-01

248

Status of the Consolidation of the LHC Superconducting Magnets and Circuits  

NASA Astrophysics Data System (ADS)

The first LHC long shutdown (LS1) started in February 2013. It was triggered by the need to consolidate the 13 kA splices between the superconducting magnets to allow the LHC to reach safely its design energy of 14 TeV center of mass. The final design of the consolidated splices is recalled. 1695 interconnections containing 10 170 splices have to be opened. In addition to the work on the 13 kA splices, the other interventions performed during the first long shut-down on all the superconducting circuits are described. All this work has been structured in a project, gathering about 280 persons. The opening of the interconnections started in April 2013 and consolidation works are planned to be completed by August 2014. This paper describes first the preparation phase with the building of the teams and the detailed planning of the operation. Then, it gives feedback from the worksite, namely lessons learnt and adaptations that were implemented, both from the technical and organizational points of view. Finally, perspectives for the completion of this consolidation campaign are given.

Tock, J. Ph; Atieh, S.; Bodart, D.; Bordry, F.; Bourcey, N.; Cruikshank, P.; Dahlerup-Petersen, K.; Dalin, J. M.; Garion, C.; Musso, A.; Ostojic, R.; Perin, A.; Pojer, M.; Savary, F.; Scheuerlein, C.

2014-05-01

249

Magnetic Model Trap Formation of Volyn  

Microsoft Academic Search

In the article technique of magnetic modelling trap formation of Volyn (north-west Ukraine) is considered. It is investigated magnetic properties of rock trap formation, anomalous magnetic field and connection of these parameters with a technique of maning model. The model of a magnetic field was made. The comparative analysis with others trap formations of the world was carried out. Introduction

M. V. Yusypiv

2004-01-01

250

SPICE equivalent circuit model of quantum-dot semiconductor optical amplifiers  

NASA Astrophysics Data System (ADS)

In this paper, we derive an equivalent circuit model for quantum dot semiconductor optical amplifier (QDSOA) by employing rate equations for electronic transitions between QD's levels and also the optical power propagation. The different parts of equivalent circuits interact together to represent the gain recovery process, saturation properties and chirp behaviour in both linear and nonlinear operation regimes of QD-SOA. The equivalent circuits are then used for SPICE simulation. We have shown that SPICE simulation results agree well with the full numerically calculated results.

Rostami, A.; Maram Q, R.; Baghban, H.; Rasooli S., H.; Ghorbani, R.

2009-11-01

251

A Review of Transcranial Magnetic Stimulation in the in vivo Functional Evaluation of Central Cholinergic Circuits in Dementia  

Microsoft Academic Search

Central cholinergic circuits of human brain can be tested non-invasively by coupling electrical peripheral stimulation with transcranial magnetic stimulation (TMS) of the motor cortex. The short-latency afferent inhibition (SAI) is reduced in cholinergic forms of dementia, such as Alzheimer disease (AD) and dementia with Lewy bodies, while it is normal in non-cholinergic forms of dementia, such as frontotemporal dementia. This

Raffaele Nardone; Stefan Golaszewski; Gunther Ladurner; Frediano Tezzon; Eugen Trinka

2011-01-01

252

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

253

RF equivalent circuit modeling of ferrite-core inductors and characterization of core materials  

Microsoft Academic Search

Ferrite-core inductors play an important role in electromagnetic noise suppression. The radio-frequency (RF) equivalent circuit modeling of the inductor is very useful for characterizing the inductor and for noise filtering studies. A technique is proposed for extracting the equivalent circuit parameters of the inductor and determining the frequency-dependent effective rod permeability as well as the intrinsic permeability of the ferrite-core

Qin Yu; Thomas W. Holmes; Krishna Naishadham

2002-01-01

254

Modeling, simulation and design techniques for high-density complex photonic integrated devices and circuits  

Microsoft Academic Search

High-density photonic integration based on the high-contrast optical waveguide structures has become increasingly appealing for realizing multi-functional photonic circuits of compact size. In the meanwhile, accurate and efficient modeling, simulation and design of such devices and circuits become increasingly challenging. Effects such as the vector nature of the fields, the reflection at waveguide junctions, and enhanced optical nonlinearity, etc., need

Ning-Ning Feng

2005-01-01

255

A Broadband Single-Stage Equivalent Circuit for Modeling LTCC Bandpass Filters  

Microsoft Academic Search

A single-stage equivalent circuit is proposed to model microwave bandpass filters (BPFs) fabricated in low-temperature co-fired ceramic (LTCC) technology up to several times its passband frequency. The equivalent circuit adopts a modified T topology with the expandable multilayer resonators to achieve an extremely large bandwidth. It can be efficiently established from the measured S-parameters using direct extraction or rational approximation.

Yu-Shun Tsai; Tzyy-Sheng Horng

2006-01-01

256

Total Dose and Dose Rate Models for Bipolar Transistors in Circuit Simulation.  

National Technical Information Service (NTIS)

The objective of this work is to develop a model for total dose effects in bipolar junction transistors for use in circuit simulation. The components of the model are an electrical model of device performance that includes the effects of trapped charge on...

P. M. Campbell S. D. Wix

2013-01-01

257

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

SciTech Connect

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 exits between the measured and the simulated results.

Keshavarz, A.A. [Alliance Technologies, Inc., Albuquerque, NM (United States); Raney, C.W.; Campbell, D.C. [Sandia National Labs., Albuquerque, NM (United States)

1993-08-01

258

Predicting microbial growth kinetics with the use of genetic circuit models  

Microsoft Academic Search

A novel modeling approach for the description of bioprocesses is proposed, linking microbial growth kinetics to gene regulation. An example is given with the development and experimental validation of a dynamic mathematical model of the TOL plasmid of Pseudomonas putida mt-2, which is used for the metabolism of m-xylene. The model of this genetic circuit is coupled to a growth

Michalis Koutinas; Alexandros Kiparissides; Victor de Lorenzo; Vitor A. P. Martins dos Santos; Efstratios N. Pistikopoulos; Athanasios Mantalaris

2011-01-01

259

Electrical Circuit Analysis of Coplanar Plasma Display Panels Using a Simple Discharge Model  

Microsoft Academic Search

We have developed a simple method of modeling the electrical characteristics of a plasma display panel discharge. We analyze the discharge phenomena of coplanar plasma display panels (PDPs), and the model is sufficiently simple to express the electrical characteristics of the phenomena. Being a combination of primitive electric elements, this model can be calculated using a general-purpose circuit simulator, which

Taichiro Tamida; Akihiko Iwata; Jun-ichi Nishimae; Masaaki Tanaka

2001-01-01

260

Effective transient process modelling of the reflow soldering of printed circuit assemblies  

Microsoft Academic Search

Process modelling of the reflow soldering of Printed Circuit Assemblies (PCAs) requires complex thermal models incorporating a number of modes of heat transfer, including radiation (infra red) and (forced\\/free) convection. This paper describes the development of representative process models of the reflow soldering of PCAs and outlines some of the more important parameters to consider for accurate simulation of the

Farhad Sarvar; Paul P. Conway

1996-01-01

261

A process model of the infra-red reflow soldering of printed circuit board assemblies  

Microsoft Academic Search

The authors present the latest results of an evolving model of the infra-red reflow soldering process. Recent additions to earlier models are the convective cooling of the PCB (printed circuit board) as it exits from the furnace muffle, and the addition of realistic component structures to the PCB assembly. The authors also present the initial results from a second model

David C Whalley; A. Ogunjimi; P. P. Conway; D. J. Williams

1991-01-01

262

Analysis of the Temperature Characteristics in Polycrystalline Si Solar Cells Using Modified Equivalent Circuit Model  

Microsoft Academic Search

We have evaluated the influence of grain boundaries on the temperature dependence of cell performance using a modified 2-diode equivalent circuit model. In this model, microscopic inhomogeneity of resistivity at or near grain boundaries can be taken into consideration. The calculated results by the modified 2-diode model agreed well with the measured current-voltage curves, and the validity of the fitting

Kensuke Nishioka; Nobuhiro Sakitani; Ken-ichi Kurobe; Yukie Yamamoto; Yasuaki Ishikawa; Yukiharu Uraoka; Takashi Fuyuki

2003-01-01

263

Small signal equivalent circuit modeling of the LCC-type parallel resonant converter  

Microsoft Academic Search

A small signal equivalent circuit model is obtained for the LCC-type parallel resonant converter in the form of a two port hybrid parameter model. This model is used to study the small signal behavior of the converter. Dynamic performance parameters like the control to output transfer function, audio-susceptibility, output impedance and input admittance have been plotted. Both exact (sampled) and

Vivek Agarwal; A. K. S. Bhat

1995-01-01

264

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

265

Optical Imaging as a Link Between Cellular Neurophysiology and Circuit Modeling  

PubMed Central

The relatively simple and highly modular circuitry of the cerebellum raised expectations decades ago that a realistic computational model of cerebellar circuit operations would be feasible, and prove insightful for unraveling cerebellar information processing. To this end, the biophysical properties of most cerebellar cell types and their synaptic connections have been well characterized and integrated into realistic single cell models. Furthermore, large scale models of cerebellar circuits that extrapolate from single cell properties to circuit dynamics have been constructed. While the development of single cell models have been constrained by microelectrode recordings, guidance and validation as these models are scaled up to study network interactions requires an experimental methodology capable of monitoring cerebellar dynamics at the population level. Here we review the potential of optical imaging techniques to serve this purpose.

Akemann, Walther; Middleton, Steven J.; Knopfel, Thomas

2009-01-01

266

Microfluidic primary culture model of the lower motor neuron-neuromuscular junction circuit.  

PubMed

Modelling the complex process of neuromuscular signalling is key to understanding not only normal circuit function but also importantly the mechanisms underpinning a range of degenerative diseases. We describe a novel in vitro model of the lower motor neuron-neuromuscular junction circuit, incorporating primary spinal motor neurons, supporting glia and skeletal muscle. This culture model is designed to spatially mimic the unique anatomical and cellular interactions of this circuit in compartmented microfluidic devices, such that the glial cells are located with motor neuron cell bodies in the cell body chamber and motor neuron axons extend to a distal chamber containing skeletal muscle cells whilst simultaneously allowing targeted intervention. This model is suitable for use in conjunction with a range of downstream experimental approaches and could also be modified to utilise other cellular sources including appropriate immortal cell lines, cells derived from transgenic models of disease and also patient derived stem cells. PMID:23774648

Southam, Katherine A; King, Anna E; Blizzard, Catherine A; McCormack, Graeme H; Dickson, Tracey C

2013-09-15

267

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

268

Using Simple Circuits as Thermal Models for Your Home  

NASA Astrophysics Data System (ADS)

In 2009, President Obama proposed an initiative to decrease our country's energy consumption and dependence on fossil fuels. One key to this plan was to decrease the amount of energy used to heat and cool our homes through government incentives. The EPA estimates that the average American household spends over 1000 annually for heating and cooling.1 One of the most cost-effective ways of decreasing energy use in your home is to stop air penetration and increase the amount of insulation by installing insulated doors, insulated windows, and cavity wall insulation. But not all options are equally effective, nor do they have equal costs. So how can consumers determine which option improves their homes' insulation the most? In this paper, I present an analogy to simple resistor circuits that can be used by introductory students to answer this question.

Poynor, Adele

2014-02-01

269

Equivalent circuit model of quantum dot semiconductor optical amplifiers: dynamic behaviour and saturation properties  

NASA Astrophysics Data System (ADS)

In this paper, we derive an equivalent circuit model for a quantum dot semiconductor optical amplifier (QD-SOA) by employing rate equations for electronic transitions between the QD's levels and also the optical power propagation. The different parts of the equivalent circuits interact together to represent the gain recovery process, saturation properties and chirp behaviour in both linear and nonlinear operation regimes of the QD-SOA. The equivalent circuits are then used for SPICE simulation. We have also applied a control pulse to decrease the gain recovery time using the cross-gain modulation (XGM) effect, and the equivalent circuit of this source has been discussed. The Tb s-1 operation capability can be illustrated using this approach. We have shown that SPICE simulation results agree well with the full numerically calculated results.

Maram Q, R.; Baghban, H.; Rasooli S, H.; Ghorbani, R.; Rostami, A.

2009-10-01

270

Dynamic modelling of thyristor-based static switching circuits with application to power systems  

NASA Astrophysics Data System (ADS)

This work details a systematic approach to the modelling of thyristor-based static switching circuits typical of power systems. Such circuits are difficult to analyze on two counts: (1) the order of the circuit changes with thyristor transitions and (2) the uncontrolled state dependent turn-off associated with thyristors. These difficulties are overcome by a convenient linearization. The linearization permits the synthesis of linear, time-invariant (LTI) state-space models of thyristor-based static switching circuits for small-signal dynamic analysis. LTI models are synthesized for three conventional thyristor-based static switching circuits which find application in power systems: namely the Thyristor Controlled Series Capacitor (TCSC), the High Voltage direct current (HVdc) converter, and the Static VAr Compensator (SVC). The developed LTI models are valid in the vicinity of the frequency at which the system is linearized. Such models are suited to the study of the system small-signal dynamics by computation of the eigenvalues in the vicinity of the system frequency and to controller synthesis by standard linear techniques. Relevant applications to power systems analysis are presented, namely (1) the application of time-domain linearization to the computation of HVdc converter harmonics, (2) the prediction of resonance in a single-phase rectifier interacting with a power system and (3) linearized dynamic analysis of a TCSC compensated generator/transmission system by eigenvalue analysis.

Perkins, Brian Kenneth

1997-08-01

271

Magnetic Force Three Wires Model  

NSDL National Science Digital Library

The Magnetic Force Three Wires model investigates the force between long straight current-carrying wires. Initially, the simulation shows a cross-section view of three long straight parallel wires, each on the corner of an equilateral triangle. The wires carry currents that have different magnitudes, and the currents are directed either into or out of the page. The task in this simulation is to rank the wires based on the magnitude of their currents, from largest to smallest. The Magnetic Force Three Wires 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_Three_Wires.jar file will run the program if Java is installed. This is part of a collection of similar tutorial simulations created by the author.

Duffy, Andrew

2009-10-20

272

Development of 72kV Class Environmentally-Benign CO2 Gas Circuit Breaker Model  

NASA Astrophysics Data System (ADS)

Adopting CO2 as an alternative gas of SF6 in a gas circuit breaker from the environmental viewpoint, a 72kV-31.5kA class CO2 gas circuit breaker (CO2-GCB) model, which does not contain SF6 gas at all, was designed, and produced. In the CO2-GCB model, some effective technologies for current interruption by CO2 gas were adopted; namely, puffer pressure enhancing techniques utilizing arc energy during a current interruption and ablation phenomena of a polymer element located in the puffer cylinder. As a result of current interruption and electric insulation tests, the CO2-GCB model achieved practical levels of performance. Furthermore, it was found by carrying out a life cycle assessment (LCA) that the CO2-GCB model could reduce the global warming impact by about 40% compared to the latest SF6 gas circuit breaker in the same rating for 20 years operation including one maintenance opportunity.

Uchii, Toshiyuki; Hoshina, Yoshikazu; Miyazaki, Kensaku; Mori, Tadashi; Kawano, Hiromichi; Nakamoto, Tetsuya; Hirano, Yoshihiko

273

Design of a 270ps-access 7-transistor/2-magnetic-tunnel-junction cell circuit for a high-speed-search nonvolatile ternary content-addressable memory  

NASA Astrophysics Data System (ADS)

A novel 7-transistor/2-magnetic-tunnel-junction (7 T-2MTJ) cell circuit is proposed for a high-speed and compact nonvolatile ternary content-addressable memory (TCAM). Since critical path for switching in the TCAM cell circuit, which determines the performance of the TCAM, is only a single MOS transistor, switching delay of the TCAM word circuit is minimized. As a result, 270 ps of switching delay in 144-bit TCAM word circuit is achieved under a 90 nm CMOS/MTJ technology with magneto-resistance ratio of 100%, which is about two times faster than a conventional CMOS-based TCAM.

Matsunaga, Shoun; Katsumata, Akira; Natsui, Masanori; Endoh, Tetsuo; Ohno, Hideo; Hanyu, Takahiro

2012-04-01

274

V.DMOS transistor modeling for simulation of power electronic circuits  

NASA Astrophysics Data System (ADS)

A nonlinear, short channel model of a power V.DMOS transistor, the elements of which depend only on physical and technological data, is presented. By an analysis of the active regions of the V.DMOS structure, in order to study switching modes, this model is simplified to a topology compatible with the SPICE circuit simulator. Parameter extraction methods and validation programs are described. A software library of the SPICE models is created by testing the transistors (N and P channels) covering the available current handling capability 2A to 50A and blocking range 50V to 1000V. A V.DMOS unified model is presented. It requires establishment of two parameters: drain source breakdown voltage, and silicon chip area. An established program linked in Hypercard with SPICE, gives an exact model for characterizing transistors as well as a model for new devices. This modeling takes into account the crystal temperature and several validation tests. Adaptation of the model for irradiation applications is pointed out by comparison between measured and computed characteristics. Use of this model to analyze bridge leg circuit properties and comparison between simulated results and measured data, confirms its application in power electronic circuits. Some problems associated with parasitic elements in these circuits are described.

Napieralska, Malgorzata

1991-08-01

275

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

276

Numerical Modelling of a Magnetic Source.  

National Technical Information Service (NTIS)

A numerical magnetic source model which reproduces a given set of magnetic field measurements to any desired degree of accuracy is derived from first principles. The model is a combination of independent discrete and continuous distributions of independen...

A. G. Theobald

1986-01-01

277

Modeling Magnetic Properties in EZTB  

NASA Technical Reports Server (NTRS)

A software module that calculates magnetic properties of a semiconducting material has been written for incorporation into, and execution within, the Easy (Modular) Tight-Binding (EZTB) software infrastructure. [EZTB is designed to model the electronic structures of semiconductor devices ranging from bulk semiconductors, to quantum wells, quantum wires, and quantum dots. EZTB implements an empirical tight-binding mathematical model of the underlying physics.] This module can model the effect of a magnetic field applied along any direction and does not require any adjustment of model parameters. The module has thus far been applied to study the performances of silicon-based quantum computers in the presence of magnetic fields and of miscut angles in quantum wells. The module is expected to assist experimentalists in fabricating a spin qubit in a Si/SiGe quantum dot. This software can be executed in almost any Unix operating system, utilizes parallel computing, can be run as a Web-portal application program. The module has been validated by comparison of its predictions with experimental data available in the literature.

Lee, Seungwon; vonAllmen, Paul

2007-01-01

278

Dynamic modeling of short-circuit behavior of a six-pulse rectifier  

Microsoft Academic Search

Existing models describing the dynamic behavior of a six-pulse rectifier during a short-circuit fault condition are derived from switch models using average value parametric functions. Unlike these models, new non-parametric dynamic models have been developed using analytical average-value mod- eling approach. In this modeling approach, depending upon the number of switches conducting during a switching cycle, the operating point of

Pandarinath Murali; Surya Santoso

2011-01-01

279

Study of Magnetic and Electric Coupling for Contactless Power Transfer Using Equivalent Circuits  

NASA Astrophysics Data System (ADS)

This paper proposes a novel method of contactless power transfer from a transmitting antenna to a receiving antenna. This method involves electromagnetic coupling of near-field antennas at resonance. However, the exact manner in which method this method can be used to design antennas and circuits has not been clarified. Therefore, this study focuses on defining the exact frequency and efficiency required fore electromagnetic coupling on the basis of the antenna theory, circuit theory, experimental observations, and electromagnetic computations and experiments.

Imura, Takehiro; Okabe, Hiroyuki; Uchida, Toshiyuki; Hori, Yoichi

280

An equivalent circuit model of Frequency Selective Surfaces embedded within dielectric layers  

Microsoft Academic Search

A general equivalent circuit model for the analysis of frequency selective surfaces has been presented. The lumped parameters representing the periodic surface are explained and commented. Influence of thin dielectric substrates on FSS behavior is analyzed determining a simple model to correct the lumped parameters. FSS periodicity can be changed by scaling all lumped parameters by the initial and actual

Filippo Costa; Agostino Monorchio; Giuliano Manara

2009-01-01

281

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

282

Design of basic digital circuit blocks based on an OFET device charge model  

NASA Astrophysics Data System (ADS)

An OFET charge model, as well as its parameter extraction method are presented. The fitting results are also discussed and different OFET model characters are compared. Some basic OFET based digital circuit blocks, including the inverter, NAND, and ring oscillator are also developed, which would be considered to be helpful to the design of relevant applications.

Shu, Shen

2013-05-01

283

Approximated models for the analysis of interconnected circuits with transmission lines  

Microsoft Academic Search

A new method for the time-domain response computation of an interconnected circuit with transmission lines is proposed. In the first step, a lumped approximated model of each transmission line is computed. In the second step, a model-order reduction of the resulting system is performed by means of balancing approximation techniques. An example is shown to validate the suitability of the

R. Carrara; L. Fortuna; G. Muscato; M. G. Xibilia

1992-01-01

284

New circuital models of grounding systems and PDS for EMI analysis during a lightning strike  

Microsoft Academic Search

In this paper circuital models of a power drive system (PDS) and of grounding systems are proposed in order to analyse electromagnetic interferences (EMI) induced in a PDS when a lightning current flows in the grounding system. The models have been developed adopting the network approach with lumped parameters and have been implemented using the software Matlab. A high frequency

Vittorio Cecconi; Antonino Matranga; Antonella Ragusa

2005-01-01

285

Power transistor models with temperature dependent parasitic effects for SPICE-like circuit simulation  

Microsoft Academic Search

New SPICE-like simulation models for a power MOSFET containing a dynamic link between electrical and thermal component descriptions were described. The designed electro-thermal MOSFET model consists of several parts which represent different transistor behavior at different conditions as reverse bias, avalanche breakdown, thermal burning and others. Modified thermal equivalent circuit diagrams were designed taking into account thermal dependence of thermal

A. Chvala; D. Donoval; J. Marek; P. Pribytny; M. Molnar

2012-01-01

286

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

287

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

288

Computation of equivalent circuit models of optically driven CPW-fed slot antennas for wireless communications  

Microsoft Academic Search

The paper presents a quasi-TEM equivalent circuit model for two optically driven coplanar waveguide (CPW)-fed slot antennas. This model takes into account both the electromagnetic fields in the CPW structure as well as the effects of the discontinuities of the antenna design. The results are compared with simulations taken from IE3d using the method of moments.

G. Tzeremes; Tsai S. Liao; Paul K. L. Yu; C. G. Christodoulou

2003-01-01

289

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

290

Step-Wise Evolution of Mental Models of Electric Circuits: A "Learning-Aloud" Case Study.  

ERIC Educational Resources Information Center

Describes an approach to teaching complex models in science that uses a model construction cycle of generation, evaluation, and modification. Reports on a case study of a student in a tutoring experiment in the study of electric circuits. Focuses on the role of analogies, discrepant events, and the student's moments of surprise as motivators of…

Clement, John J.; Steinberg, Melvin S.

2002-01-01

291

Estimation of short circuit current due to a group of induction motors using an aggregation model  

Microsoft Academic Search

This paper presents generalized equations for determining an aggregation model to represent a group of induction motors connected in the same bus of industrial power systems. The model is employed in calculating short circuit current contribution with different types of faults from the group of induction motors. The simulation and analysis are performed using PSCAD\\/EMTDC. Various case studies are used

W. Suwanwej; A. Kunakorn

2004-01-01

292

Physics-based models of power semiconductor devices for the circuit simulator SPICE  

Microsoft Academic Search

Models of power semiconductor devices are implemented in the circuit simulator PSpice. The combination of subcircuits and mathematical functions enables very compact solutions. High accuracy and validity in a wide operation range are obtained due to the derivation from device physics. Models of the power diode and the IGBT are presented as examples

R. Kraus; P. Tiirkes; J. Sigg

1998-01-01

293

Computer model for air-cooled refrigerant condensers with specified refrigerant circuiting  

SciTech Connect

A computer model for an air-cooled refrigerant condensor is presented; the model is intended for use in detailed design analyses or in simulation of the performance of existing heat exchangers that have complex refrigerant circuiting or unusual air-side geometries. The model relies on a tube-by-tube computational approach calculating the thermal and fluid-flow performance of each tube in the heat exchanger individually, using local temperatures and heat transfer coefficients. The refrigerant circuiting must be specified; the joining or branching of parallel circuits is accommodated using appropriate mixing expressions. Air-side heat exchange correlations may be specified so that various surface geometries can be investigated. Results of the analyses of two condensers are compared to experiment.

Ellison, R.D.; Creswick, F.A.; Fischer, S.K.; Jackson, W.L.

1981-01-01

294

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

NASA Astrophysics Data System (ADS)

Hybrid Nano (e.g. Nanotube and Nanowire) /CMOS circuits combine both the advantages of Nano-devices and CMOS technologies; they have thus become the most promising candidates to relax the intrinsic drawbacks of CMOS circuits beyond Moore’s law. A functional simulation model for an hybrid Nano/CMOS design is presented in this paper. It is based on Optically Gated Carbon NanoTube Field Effect Transistors (OG-CNTFET), which can be used as 2-terminal programmable resistors. Their resistance can be adjusted precisely, reproducibly and in a non-volatile way, over three orders of magnitude. These interesting behaviors of OG-CNTFET promise great potential for developing the non-volatile memory and neuromorphic adaptive computing circuits. The model is developed in Verilog-A language and implemented on Cadence Virtuoso platform with Spectre 5.1.41 simulator. Many experimental parameters are included in this model to improve the simulation accuracy.

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

295

Analyzing the effects of post couplers in DTL tuning by the equivalent circuit model  

NASA Astrophysics Data System (ADS)

Stabilization of the accelerating field in Drift Tube Linac(DTL) is obtained by inserting Post Couplers(PCs). On the basis of the equivalent circuit model for the DTL with and without asymmetrical PCs, stabilization is deduced quantitatively: we let ??/?0 be the relative frequency error, then we discover that the sensitivity of field to perturbation is proportional to without PCs and to ??/?0 with PCs. Then we adapt the circuit model of symmetrical PCs for the case of asymmetrical PCs. The circuit model shows how the slope of field distribution is changed by rotating the asymmetrical PCs and illustrates that the asymmetrical PCs have the same effect as the symmetrical ones in stabilization.

Jia, Xiao-Yu; Zheng, Shu-Xin

2013-12-01

296

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

297

Lumped-circuit models for nonlinear inductors exhibiting hysteresis loops  

Microsoft Academic Search

A new mathematical model of dynamic hysteresis loops is presented. The model is completely specified by two strictly monotonically increasing functions: a restoring function f(.) and a dissipation function g(.). Simple procedures are given for constructing these two functions so that the resulting model will simulate a given hysteresis loop exactly. The model is shown to exhibit many important hysteretic

L. Chua; K. Stromsmoe

1970-01-01

298

TLM modeling of transformer with internal short circuit faults  

Microsoft Academic Search

Purpose – The purpose of this paper is to describe a technique for modeling transformer internal faults using transmission line modeling (TLM) method. In this technique, a model for simulating a two winding single phase transformer is modified to be suitable for simulating an internal fault in both windings. Design\\/methodology\\/approach – TLM technique is mainly used for modeling transformer internal

Okan Ozgonenel; David W. P. Thomas; Christos Christopoulos

2007-01-01

299

Circuital characteristics and radiation properties of an UWB electric-magnetic planar antenna for Ku-band applications  

NASA Astrophysics Data System (ADS)

A planar, directive antenna with large fractional bandwidth is introduced in this paper. A detailed discussion on the proposed antenna topology and its architecture is reported. The proposed element is a combination of a patch and a loop radiator. A proper combination of the electric field radiator (patch) with a magnetic field radiator (loop around the patch) is exploited for expanding the operational bandwidth. A parametric study is presented to investigate the effect of the antenna geometrical parameters on its performance. A general and computationally efficient procedure for extracting the antenna equivalent circuit is described and used to achieve a meaningful circuit theory-based insight into the characteristics of the radiating structure. The theoretical and experimental results are compared, and it is demonstrated that the element features over 100% fractional bandwidth, good impedance matching, and unidirectional and stable radiation patterns.

Haider, N.; Caratelli, D.; Yarovoy, A. G.

2013-01-01

300

Analysis of single-event upset of magnetic tunnel junction used in spintronic circuits caused by radiation-induced current  

NASA Astrophysics Data System (ADS)

This paper describes the possibility of a switching upset of a magnetic tunnel junction (MTJ) caused by a terrestrial radiation-induced single-event-upset (SEU) current in spintronic integrated circuits. The current waveforms were simulated by using a 3-D device simulator in a basic circuit including MTJs designed using 90-nm CMOS parameters and design rules. The waveforms have a 400 -?A peak and a 200-ps elapsed time when neutron particles with a linear energy transfer value of 14 MeV cm2/mg enter the silicon surface. The authors also found that the SEU current may cause soft errors with a probability of more than 10-12 per event, which was obtained by approximate solution of the ordinary differential equation of switching probability when the intrinsic critical current (IC0) became less than 30 ?A.

Sakimura, N.; Nebashi, R.; Natsui, M.; Ohno, H.; Sugibayashi, T.; Hanyu, T.

2014-05-01

301

Strongly magnetized classical plasma models  

NASA Technical Reports Server (NTRS)

Discrete particle processes in the presence of a strong external magnetic field were investigated. These processes include equations of state and other equilibrium thermodynamic relations, thermal relaxation phenomena, transport properties, and microscopic statistical fluctuations in such quantities as the electric field and the charge density. Results from the equilibrium statistical mechanics of two-dimensional plasmas are discussed, along with nonequilibrium statistical mechanics of the electrostatic guiding-center plasma (a two-dimensional plasma model).

Montgomery, D.; Peyraud, J.; Dewitt, C.

1974-01-01

302

A wideband lumped circuit model of eddy current losses in a coil with a coaxial insulation system and a stranded conductor  

Microsoft Academic Search

This paper presents a wideband lumped circuit model of eddy current losses in a coaxially insulated coil. The wide frequency range of the model is achieved by means of dual and extended Cauer circuits, which are equivalent circuits used for eddy current modeling. The complete lumped circuit reproduces the expected response well. However, because of resonances in the coil, the

Pär Holmberg; Mats Leijon; Torbjörn Wass

2003-01-01

303

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

304

Equivalent circuit of radio frequency-plasma with the transformer model.  

PubMed

LINAC4 H(-) source is radio frequency (RF) driven type source. In the RF system, it is required to match the load impedance, which includes H(-) source, to that of final amplifier. We model RF plasma inside the H(-) source as circuit elements using transformer model so that characteristics of the load impedance become calculable. It has been shown that the modeling based on the transformer model works well to predict the resistance and inductance of the plasma. PMID:24593557

Nishida, K; Mochizuki, S; Ohta, M; Yasumoto, M; Lettry, J; Mattei, S; Hatayama, A

2014-02-01

305

A framework for scalable parameter estimation of gene circuit models using structural information  

PubMed Central

Motivation: Systematic and scalable parameter estimation is a key to construct complex gene regulatory models and to ultimately facilitate an integrative systems biology approach to quantitatively understand the molecular mechanisms underpinning gene regulation. Results: Here, we report a novel framework for efficient and scalable parameter estimation that focuses specifically on modeling of gene circuits. Exploiting the structure commonly found in gene circuit models, this framework decomposes a system of coupled rate equations into individual ones and efficiently integrates them separately to reconstruct the mean time evolution of the gene products. The accuracy of the parameter estimates is refined by iteratively increasing the accuracy of numerical integration using the model structure. As a case study, we applied our framework to four gene circuit models with complex dynamics based on three synthetic datasets and one time series microarray data set. We compared our framework to three state-of-the-art parameter estimation methods and found that our approach consistently generated higher quality parameter solutions efficiently. Although many general-purpose parameter estimation methods have been applied for modeling of gene circuits, our results suggest that the use of more tailored approaches to use domain-specific information may be a key to reverse engineering of complex biological systems. Availability: http://sfb.kaust.edu.sa/Pages/Software.aspx Contact: xin.gao@kaust.edu.sa Supplementary information: Supplementary data are available at Bioinformatics online.

Kuwahara, Hiroyuki; Fan, Ming; Wang, Suojin; Gao, Xin

2013-01-01

306

A simple model of EMI-induced timing jitter in digital circuits, its statistical distribution and its effect on circuit performance  

Microsoft Academic Search

A simple model has been developed to characterize electromagnetic interference induced timing variations (jitter) in digital circuits. The model is based on measurable switching parameters of logic gates, and requires no knowledge of the internal workings of a device. It correctly predicts not only the dependence of jitter on the amplitude, modulation depth and frequency of the interfering signal, but

Martin P. Robinson; Katharina Fischer; Ian D. Flintoft; Andrew C. Marvin

2003-01-01

307

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

308

Fast expansion of a plasma beam controlled by short-circuiting effects in a longitudinal magnetic field  

NASA Astrophysics Data System (ADS)

The transverse expansion of a plasma beam with finite ion gyroradius injected along a magnetic field has been treated analytically and numerically in low 0963-0252/5/4/016/img1 plasma. It has been demonstrated that the transverse expansion of a beam is much faster than predicted by standard ambipolar diffusion owing to the short-circuiting currents in the system. In the vicinity of an injector, plasma expands with the sound speed while at larger distances the transverse velocity tends to zero and a cylindrical shape of the beam is formed.

Kaganovich, I. D.; Rozhansky, V. A.; Tsendin, L. D.; Veselova, I. Yu

1996-11-01

309

A negative-capacitance equivalent circuit model for parallel-plate capacitive-gap-transduced micromechanical resonators.  

PubMed

A small-signal equivalent circuit for parallelplate capacitive-gap-transduced micromechanical resonators is introduced that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates circuit analysis, that better elucidates the mechanisms behind certain potentially puzzling measured phenomena, and that inspires circuit topologies that maximize performance in specific applications. For this work, a micromechanical disk resonator serves as the vehicle with which to derive the equivalent circuits for both radial-contour and wine-glass modes, which are then used in circuit simulations (via simulation) to match measurements on actual fabricated devices. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive- gap-transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for applications that must be stable against environmental perturbations, such as acceleration or power supply variations. Measurements on fabricated devices confirm predictions by the new model of up to 4× improvement in frequency stability against dc-bias voltage variations for contour- mode disk resonators as the resistance loading their ports increases. By enhancing circuit visualization, this circuit model makes more obvious the circuit design procedures and topologies most beneficial for certain mechanical circuits, e.g., filters and oscillators. PMID:24801124

Akgul, Mehmet; Wu, Lingqi; Ren, Zeying; Nguyen, Clark

2014-05-01

310

Dynamic characteristics considering vehicle load and jerk condition of Linear Induction Motor by using equivalent circuit with electro-magnetic field theory  

Microsoft Academic Search

Summary form of only given: For the dynamic analysis of Linear Induction Motor (LIM), the derivation of its equivalent circuit parameters are essential, so this paper applies those parameters derived by electro-magnetic field theory. In case of LIM, the value of parameters is different according to its secondary structure, the application of electro-magnetic field theory is not avoidable. Using those

Seok-Myeong Jang; Yu-Seop Park; Kyoung-Jin Ko; Ji-Hoon Park; Jung-Ho Lee

2010-01-01

311

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

312

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

313

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

314

Improved analytical model of the transverse coupling impedance of ferrite kicker magnets  

NASA Astrophysics Data System (ADS)

A transformer model of ferrite kicker magnets is presented in this paper. Based on this model, an equivalent circuit is derived for which the elements can be obtained by bench measurements or by estimates from the magnet geometry. Improved formulas for the transverse coupling impedance of lumped and traveling wave kicker magnets are derived from the model and the equivalent circuit. The formulas differ from the corresponding handbook results in their dependence on the external termination or aperture aspect, respectively. The effect of ferrite properties on the transverse coupling impedance is analyzed. The model was confirmed by bench measurements with the twin-wire technique made on the full-size and half-size prototypes of the extraction kicker of the SNS accumulator ring. The application of this model to the design of the kickers allowed a significant reduction of the SNS transverse coupling impedance budget.

Davino, Daniele; Hahn, Harald

2003-01-01

315

Device and circuit-level modeling using neural networks with faster training based on network sparsity  

Microsoft Academic Search

Recently, circuit analysis and optimization featuring neural-network models have been proposed, reducing the computational time during optimization while keeping the accuracy of physics-based models. We present a novel approach for fast training of such neural-network models based on the sparse matrix concept. The new training technique does not require any structure change in neural networks, but makes use of the

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

1997-01-01

316

Multi-physics modeling of through-silicon vias with equivalent-circuit approach  

Microsoft Academic Search

Multi-physics modeling offers rich opportunities for studying the properties of through-silicon vias (TSV). Results of a TSV study with the theories of electromagnetics, semiconductor physics, and thermal physics are presented. Equivalent circuit models are used to draw together the three different theories to perform the TSV modeling. Moreover, a single TSV is examined for high-speed signal transmission with surface waves.

En-Xiao Liu; Er-Ping Li; Wei-Bin Ewe; Hui Min Lee

2010-01-01

317

A novel modified-T equivalent circuit for modeling LTCC embedded inductors with a large bandwidth  

Microsoft Academic Search

This paper presents a new modified-T model for three-dimensional inductors embedded in the multilayer low-temperature cofired-ceramic substrate with a remarkably large bandwidth. This model combines a core circuit, a five-element modified-T model, to include the effects of a transmission line with an electrical length up to ?, and several resonators to consider the effects due to coil coupling and the

Tzyy-Sheng Horng; Jian-Ming Wu; Li-Qun Yang; Shyh-Tirng Fang

2003-01-01

318

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

319

An Empirical Model for Estimating the Probability of Electrical Short Circuits from Tin Whiskers. Part 2  

NASA Technical Reports Server (NTRS)

In this experiment, an empirical model to quantify the probability of occurrence of an electrical short circuit from tin whiskers as a function of voltage was developed. This empirical model can be used to improve existing risk simulation models. FIB and TEM images of a tin whisker confirm the rare polycrystalline structure on one of the three whiskers studied. FIB cross-section of the card guides verified that the tin finish was bright tin.

Courey, Karim; Wright, Clara; Asfour, Shihab; Onar, Arzu; Bayliss, Jon; Ludwig, Larry

2009-01-01

320

1\\/f noise synthesis model in discrete-time for circuit simulation  

Microsoft Academic Search

Flicker noise, popularly known as 1\\/f noise is a commonly observed phenomenon in semiconductor devices. To incorporate 1\\/f noise in circuit simulations, models are required to synthesize such noise in discrete time. This paper proposes a model based on the fact that 1\\/f processes belong to the class of statistically self-similar random processes. The model generates 1\\/f noise in the

Rajesh Narasimha; Sri Priya Bandi; Raghuveer M. Rao; P. R. Mukund

2005-01-01

321

Modeling power-supply disturbances in digital circuit  

Microsoft Academic Search

A model that represents errors caused by power supply disturbances as delay faults will be discussed. Experiments reveal that the error susceptibility increases at high clock rates and that metastable states may result.

M. Cortes; E. McCluskey; K. Wagner; D. Lu

1986-01-01

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

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

324

ASPECTS OF MODELLING A COMPLEX CHLORIDE LEACH CIRCUIT: STARFIELD RESOURCES' FERGUSON LAKE PROJECT  

Microsoft Academic Search

The enabling step in a chloride-based circuit being developed for processing bulk sulphide ore from Starfield Resources' Ferguson Lake deposit is the hydrolysis of ferric chloride to hematite and hydrochloric acid, the acid being recycled and the hematite being an environmentally friendly stable residue. The chemistry and thermodynamics relevant to the hydrolysis step were modeled and the results were used

Mike Dry

325

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

326

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

327

A modelling tool for the thermal optimisation of the reflow soldering of printed circuit assemblies  

Microsoft Academic Search

Thermal history variation within printed circuit assemblies (PCAs) during reflow soldering is considered one of the main drivers for manufacturing defects. It is recognised that predictive tools could be used to identify the temperature variations that arise during the reflow process and, in conjunction with experimentally derived data, determine their impact on manufacturing quality. A predictive model would also be

Farhad Sarvar; Paul P Conway

1998-01-01

328

Organic thin-film transistors modeling; simulation and design of a fully organic AMOLED pixel circuit  

Microsoft Academic Search

In this paper we implement the simulation and design of a fully organic AMOLED pixel in which OLED current driving and pixel selection is performed by organic thin-film transistors (OTFTs). An empirical SPICE-like OTFT model has been developed. A pixel with sandwich structure in which the OLED is deposited on top of the rest of the circuit has been simulated

Omid Yaghmazadeh; Yvan Bonnassieux; Amar Saboundji; Gilles Horowitz; B. Geffroy; D. Tondelier

2008-01-01

329

Network model and short circuit program for the Kennedy Space Center electric power distribution system  

NASA Technical Reports Server (NTRS)

Assumptions made and techniques used in modeling the power network to the 480 volt level are discussed. Basic computational techniques used in the short circuit program are described along with a flow diagram of the program and operational procedures. Procedures for incorporating network changes are included in this user's manual.

1976-01-01

330

Estimation of the parameters of metal oxide gapless surge arrester equivalent circuit models using genetic algorithm  

Microsoft Academic Search

In the present work a genetic algorithm is developed, for the evaluation of the parameters of metal oxide gapless surge arrester circuit models, in order to minimize the error between the computed and the measured (by the manufacturer) peak value of the residual voltage for each given current waveform and level separately. Furthermore, the algorithm is modified in order to

C. A. Christodoulou; I. F. Gonos; I. A. Stathopulos

2011-01-01

331

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

332

A conducting sheet model for efficient wide band FDTD analysis of planar waveguides and circuits  

Microsoft Academic Search

A simple wide band equivalent circuit for the surface impedance of conducting sheets is introduced into the three dimensional Yee (1966) FDTD scheme. The model is based on the plane skin effect, thus the frequency dependence of losses and of the inner inductivity is included. Stability considerations are presented as well as numerical results for the attenuation coefficient of microstrip

A. Lauer; I. Wolff

1999-01-01

333

Analysis and modeling of bang-bang clock and data recovery circuits  

Microsoft Academic Search

Abstract, A large-signal piecewise-linear model is proposed for bang-bang phase detectors that predicts characteristics of clock and data recovery circuits such as jitter transfer, jitter tolerance, and jitter generation. The results are validated by 1-Gb\\/s and 10-Gb\\/s CMOS prototypes using an Alexander phase detector and an LC oscillator.

Jri Lee; Kenneth S. Kundert; Behzad Razavi

2004-01-01

334

Flow Field Computation for Simplified High Voltage Gas Circuit Breaker Model by Upwind Meshfree Method  

NASA Astrophysics Data System (ADS)

To effectively design high voltage (HV) circuit breakers, a meshfree method which was proposed by the authors is tested. The meshfree method is implemented to a simplified model for the HV circuit breaker and showed a robust behavior even in a severe boundary condition. A good shock capturing is shown in the computations and a delicate gas diffusion through a slit is also computed, which is usually difficult to catch. Vector splitting method is employed to exploit the merit of meshfree methods in the hyperbolic problems.

Choe, Hi Jun; Ahn, Mu-Young; Song, Ki Dong; Park, Kyong-Yop; Park, Seong-Kwan

2006-12-01

335

Stress and Rodent Models of Drug Addiction: Role of VTA-Accumbens-PFC-Amygdala Circuit  

PubMed Central

Stress can trigger, intensify, and prolong drug consumption, as well as reinstate previously extinguished drug-taking behavior by directly impacting a neural circuit often referred to as a reward pathways. Animal models of drug abuse have been used to understand these neural circuits mediating stress-induced drug intake and relapse through examination of cellular and subcellular molecular mechanisms. Several types of intermittent stressors have been shown to induce cross-sensitization to psychomotor stimulants, enhance conditioned place preference under most conditions, increase self-administration of cocaine and amphetamine and induce reinstatement of heroin and cocaine seeking via activation of the mesocorticolimbic dopamine system.

Yap, Jasmine J.; Miczek, Klaus A.

2009-01-01

336

Power Optimization of a Planar Single-Channel Shim Coil for a Permanent Magnet Circuit  

NASA Astrophysics Data System (ADS)

We propose a new method of designing a power-optimized single-channel shim coil (SCSC), which enables high homogeneity in the magnetic field of a magnetic resonance imaging system. The design method is based on a superposition of multiple circular currents to account for the power dissipated in the current-carrying coils. With a power-optimized SCSC, magnetic field inhomogeneity is largely corrected and there is negligible degradation of the magnetic field in continuous use.

Terada, Yasuhiko; Ishi, Keiichiro; Tamada, Daiki; Kose, Katsumi

2013-02-01

337

Waveguide design, modeling, and optimization: from photonic nanodevices to integrated photonic circuits  

NASA Astrophysics Data System (ADS)

We present the state of the art for commercial design and simulation software in the 'front end' of photonic circuit design. One recent advance is to extend the flexibility of the software by using more than one numerical technique on the same optical circuit. There are a number of popular and proven techniques for analysis of photonic devices. Examples of these techniques include the Beam Propagation Method (BPM), the Coupled Mode Theory (CMT), and the Finite Difference Time Domain (FDTD) method. For larger photonic circuits, it may not be practical to analyze the whole circuit by any one of these methods alone, but often some smaller part of the circuit lends itself to at least one of these standard techniques. Later the whole problem can be analyzed on a unified platform. This kind of approach can enable analysis for cases that would otherwise be cumbersome, or even impossible. We demonstrate solutions for more complex structures ranging from the sub-component layout, through the entire device characterization, to the mask layout and its editing. We also present recent advances in the above well established techniques. This includes the analysis of nano-particles, metals, and non-linear materials by FDTD, photonic crystal design and analysis, and improved models for high concentration Er/Yb co-doped glass waveguide amplifiers.

Bordovsky, Michal; Catrysse, Peter; Dods, Steven; Freitas, Marcio; Klein, Jackson; Kotacka, Libor; Tzolov, Velko; Uzunov, Ivan M.; Zhang, Jiazong

2004-05-01

338

Simulation of SLF Interrupting Performance for CO2 Gas Circuit Breaker based on Serially Connected 3 Arc Models  

NASA Astrophysics Data System (ADS)

This paper shows the simulation of SLF interrupting performances for CO2 gas circuit breakers. In the SLF interruption tests using 72kV-CO2 gas model circuit breakers, very large post arc currents were measured. This point is obviously difference between CO2 circuit breaker and SF6 one. To simulate the SLF interrupting performances for the SF6 gas circuit breakers, serially connected 3 arc models were developed. In the arc model, Cassie arc model and two Mayr arc models were serially connected. It was tried to use the arc model to simulate the SLF interrupting performances for CO2 circuit breaker. As a result, it was good agreement with the measurements and simulations. The large post arc currents could be simulated by the arc model. It was shown that the SLF interrupting performance of the CO2 circuit breaker was dependent on the Mayr model simulated around voltage extinction peak. On the other hand, the performance of the SF6 gas circuit breaker was dependent on the Mayr model simulated around current zero. From the result, it proved that most severe SLF condition for the CO2 gas circuit breaker was L75 or L80.

Koshizuka, Tadashi; Udagawa, Keisuke; Shinkai, Takeshi; Uchii, Toshiyuki; Kawano, Hiromichi

339

Geometrically Frustrated Magnets as Model Systems.  

National Technical Information Service (NTIS)

The specific aim of this research program is to understand the cooperative magnetic properties of geometrically frustrated magnets which are model systems for the general phenomena of frustration. In the past year, we have continued studies of the dynamic...

P. Schiffer

2004-01-01

340

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

341

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

342

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

PubMed

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. PMID:23546385

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

2013-01-01

343

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

344

Olfactory Functions Scale with Circuit Restoration in a Rapidly Reversible Alzheimer's Disease Model  

PubMed Central

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.

Cheng, Ning; Bai, Li; Steuer, Elizabeth

2013-01-01

345

Finite-Element Circuit Model of Helical Explosive Generators.  

National Technical Information Service (NTIS)

A finite-element model for helical explosive generators (MCG's) is briefly described. Several features distinguish it from those previously published. Flux losses due to the moving point of contact between coil and armature are accounted for with a new te...

M. Cowan R. J. Kaye

1983-01-01

346

Yield Predictive Model Characterization In Analog Circuit Design  

Microsoft Academic Search

A new technique is presented that produces a characterized yield-predictive model by incorporating yield into the goal function directly. We explore the trade off between performance functions and yield estimation during the design optimization process. Through the integration of yield into the optimization process, the trade off between the performance functions can be better treated that able to produce a

S. H. M. Ah; P. R. Wilson; Andrew D. Brown

2007-01-01

347

Probabilistic maximum error modeling for unreliable logic circuits  

Microsoft Academic Search

Reliability modeling and evaluation is expected to be one of the major issues in emerging nano-devices and beyond 22nm CMOS. Such devices would have inherent propensity for gate failures due to the underlying device variabilities. Many of these failures would be transient in nature, neces- sitating the need for probabilistic logic based analysis. Cur- rent research in this area is

Karthikeyan Lingasubramanian; Sanjukta Bhanja

2007-01-01

348

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

349

Performance Comparison of Circuit Simulator Lumped Models for the Body Diode Reverse Recovery of Low Voltage Power Trench MOSFETs  

Microsoft Academic Search

Circuit simulator diode lumped models are investigated for representing the reverse recovery of low voltage power trench MOSFETs. Three previously presented models are compared in terms of internal constitution, circuit implementation, prediction accuracy and required computation power. 2D finite element simulations of a trench MOSFET cell underlie the prediction accuracy study. The purpose of this work is to obtain an

Toni López; Reinhold Elferich; Nick Koper; E. Alarcon

2006-01-01

350

Synthesis of the system modeling and signal detecting circuit of a novel vacuum microelectronic accelerometer.  

PubMed

A novel high-precision vacuum microelectronic accelerometer has been successfully fabricated and tested in our laboratory. This accelerometer has unique advantages of high sensitivity, fast response, and anti-radiation stability. It is a prototype intended for navigation applications and is required to feature micro-g resolution. This paper briefly describes the structure and working principle of our vacuum microelectronic accelerometer, and the mathematical model is also established. The performances of the accelerometer system are discussed after Matlab modeling. The results show that, the dynamic response of the accelerometer system is significantly improved by choosing appropriate parameters of signal detecting circuit, and the signal detecting circuit is designed. In order to attain good linearity and performance, the closed-loop control mode is adopted. Weak current detection technology is studied, and integral T-style feedback network is used in I/V conversion, which will eliminate high-frequency noise at the front of the circuit. According to the modeling parameters, the low-pass filter is designed. This circuit is simple, reliable, and has high precision. Experiments are done and the results show that the vacuum microelectronic accelerometer exhibits good linearity over -1 g to +1 g, an output sensitivity of 543 mV/g, and a nonlinearity of 0.94 %. PMID:22408515

Li, Dongling; Wen, Zhiyu; Wen, Zhongquan; He, Xuefeng; Yang, Yinchuan; Shang, Zhengguo

2009-01-01

351

Synthesis of the System Modeling and Signal Detecting Circuit of a Novel Vacuum Microelectronic Accelerometer  

PubMed Central

A novel high-precision vacuum microelectronic accelerometer has been successfully fabricated and tested in our laboratory. This accelerometer has unique advantages of high sensitivity, fast response, and anti-radiation stability. It is a prototype intended for navigation applications and is required to feature micro-g resolution. This paper briefly describes the structure and working principle of our vacuum microelectronic accelerometer, and the mathematical model is also established. The performances of the accelerometer system are discussed after Matlab modeling. The results show that, the dynamic response of the accelerometer system is significantly improved by choosing appropriate parameters of signal detecting circuit, and the signal detecting circuit is designed. In order to attain good linearity and performance, the closed-loop control mode is adopted. Weak current detection technology is studied, and integral T-style feedback network is used in I/V conversion, which will eliminate high-frequency noise at the front of the circuit. According to the modeling parameters, the low-pass filter is designed. This circuit is simple, reliable, and has high precision. Experiments are done and the results show that the vacuum microelectronic accelerometer exhibits good linearity over -1 g to +1 g, an output sensitivity of 543 mV/g, and a nonlinearity of 0.94 %.

Li, Dongling; Wen, Zhiyu; Wen, Zhongquan; He, Xuefeng; Yang, Yinchuan; Shang, Zhengguo

2009-01-01

352

Neuromorphic control of stepping pattern generation: a dynamic model with analog circuit implementation.  

PubMed

Animals such as stick insects can adaptively walk on complex terrains by dynamically adjusting their stepping motion patterns. Inspired by the coupled Matsuoka and resonate-and-fire neuron models, we present a nonlinear oscillation model as the neuromorphic central pattern generator (CPG) for rhythmic stepping pattern generation. This dynamic model can also be used to actuate the motoneurons on a leg joint with adjustable driving frequencies and duty cycles by changing a few of the model parameters while operating such that different stepping patterns can be generated. A novel mixed-signal integrated circuit design of this dynamic model is subsequently implemented, which, although simplified, shares the equivalent output performance in terms of the adjustable frequency and duty cycle. Three identical CPG models being used to drive three joints can make an arthropod leg of three degrees of freedom. With appropriate initial circuit parameter settings, and thus suitable phase lags among joints, the leg is expected to walk on a complex terrain with adaptive steps. The adaptation is associated with the circuit parameters mediated both by the higher level nervous system and the lower level sensory signals. The model is realized using a 0.3- complementary metal-oxide-semiconductor process and the results are reported. PMID:24808545

Zhijun Yang; Cameron, K; Lewinger, W; Webb, B; Murray, A

2012-03-01

353

DC/AC unified OTFT compact modeling and circuit design for RFID applications  

NASA Astrophysics Data System (ADS)

Organic materials and devices are gaining more and more attention in microelectronics. They are dedicated to low cost applications and easy in fabrications. Device structure and organic material characteristics are key points to achieve targeted products. Considering technology and product specifications, compact organic device modeling and circuit design are necessary to evaluate technology performance in RFID tags. This model is based on variable range hopping theory (VRH), i.e., a carrier may either hop over a small distance with a high activation energy or hop over a long distance with a low activation energy. The model has been developed using a physical basis where the model parameters can easily be extracted and it improves convergence in circuit simulations. It is also suitable for computer aided design (CAD) applications.

Fadlallah, M.; Billiot, G.; Eccleston, W.; Barclay, D.

2007-07-01

354

Modelling radiative transfer in ? circuit-breaker arcs with the P-1 approximation  

NASA Astrophysics Data System (ADS)

Radiative transfer in 0022-3727/31/13/012/img8 arc plasmas is one of the key issues in modelling circuit-breaker arcs properly. For a transient arc flow interaction model, the P-1 approximation appears to be a viable alternative, both from an efficiency and from an accuracy point of view. Evaluation of this approximation against other methods, such as the net emission coefficients model and the partial characteristics method, shows that the model handles the strong self-absorption at the arc boundary well and gives results with good accuracy. The method has been successfully implemented in a Euler arc-flow solver and the complete methodology has been applied to a high-current 0022-3727/31/13/012/img8 circuit-breaker arc. The computational results are compared with published experimental data.

Eby, S. D.; Trépanier, J. Y.; Zhang, X. D.

1998-07-01

355

Physics based lumped element circuit model for nanosecond pulsed dielectric barrier discharges  

NASA Astrophysics Data System (ADS)

This work presents a physics based circuit model for calculating the total energy dissipated into neutral species for nanosecond pulsed direct current (DC) dielectric barrier discharge (DBD) plasmas. Based on experimental observations, it is assumed that the nanosecond pulsed DBD's which have been proposed for aerodynamic flow control can be approximated by two independent regions of homogeneous electric field. An equivalent circuit model is developed for both homogeneous regions based on a combination of a resistor, capacitors, and a zener diode. Instead of fitting the resistance to an experimental data set, a formula is established for approximating the resistance by modeling plasmas as a conductor with DC voltage applied to it. Various assumptions are then applied to the governing Boltzmann equation to approximate electrical conductivity values for weakly ionized plasmas. The developed model is then validated with experimental data of the total power dissipated by plasmas.

Underwood, Thomas; Roy, Subrata; Glaz, Bryan

2013-02-01

356

A novel approach to the modeling of the indoor power line channel part I: circuit analysis and companion model  

Microsoft Academic Search

Multiconductor Transmission Line (MTL) theory is utilized here for modeling the transfer function of power cables in the indoor environment. This approach allows us to determine a circuit model that well characterizes the underlying physics of signal propagation over power-line (PL) cables and that also allows us to account for particular wiring practices common in residential and business environments. In

Thomas Banwell; Stefano Galli

2005-01-01

357

Body composition modeling in the calf using an equivalent circuit model of multi-frequency bioimpedance analysis  

Microsoft Academic Search

An equivalent electrical circuit model is used to describe the response of different tissue components in the calf to multi-frequency current. This model includes seven electrical components: skin resistance, contact capacitance, fat resistance, fat capacitance, extracellular resistance, intracellular resistance and cell membrane capacitance. Calf bioimpedance was measured on 30 pts using a multi-frequency bioimpedance device (Xitron 4200) with a range

Fansan Zhu; Edward F Leonard; Nathan W Levin

2005-01-01

358

Magnetic field properties of SSC model dipole magnets  

SciTech Connect

SSC 1.5m model dipole magnets were built and tested at Fermilab. Magnetic field properties were studied in term of transfer function variation and multipole components. The results were satisfactory. Observation of periodicity of remanent field along the axis is also reported.

Wake, M.; Bossert, R.; Carson, J.; Delchamps, S.; Jaffery, T.S.; Kinney, W.; Koska, W.; Lamm, M.J.; Strait, J. (Fermi National Accelerator Lab., Batavia, IL (United States)); Butteris, J.; Sims, R.; Winters, M. (Superconducting Super Collider Lab., Dallas, TX (United States))

1992-09-01

359

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

360

A process\\/physics-based compact model for nonclassical CMOS device and circuit design  

Microsoft Academic Search

A process\\/physics-based compact model (UFDG) for nonclassical MOSFETs having ultra-thin Si bodies (UTB) is overviewed. The model, in essence, is a compact Poisson–Schrödinger solver, including accountings for short-channel effects, and is applicable to nanoscale fully depleted (FD) SOI MOSFETs as well as generic double-gate (DG) devices. The utility of UFDG in nonclassical CMOS device design, as well as circuit design,

J. G. Fossum; L. Ge; M.-H. Chiang; V. P. Trivedi; M. M. Chowdhury; L. Mathew; G. O. Workman; B.-Y. Nguyen

2004-01-01

361

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

362

Modelling and simulation of nozzle ablation in high-voltage circuit-breakers  

NASA Astrophysics Data System (ADS)

In the present paper, a new approach to modelling the ablation phenomenon using computational fluid dynamics (CFD) tools coupled with a physical radiation model is proposed, implemented and validated for application in circuit-breaker arc studies. The present work shows that the principal characteristics of ablation-dominated arcs can be simulated effectively using CFD tools if the radiation incident at the wall boundaries can be predicted accurately.

Godin, D.; Trépanier, J. Y.; Reggio, M.; Zhang, X. D.; Camarero, R.

2000-10-01

363

Accurate modeling of voltage and current waveforms with saturation and power losses in a ferrite core via two-dimensional finite elements and a circuit simulator  

NASA Astrophysics Data System (ADS)

This paper presents a new dynamic model of equivalent circuit to simulate in the time-domain the effects of saturation and power losses in a nonlinear magnetic component. The parameters of the model are a nonlinear inductance and a nonlinear loss resistance that are computed via two-dimensional finite elements. The effectiveness of the model is analyzed in the case of a soft ferrite inductor excited by a sinusoidal voltage source at frequencies of 500 Hz and 40 kHz. The resulting voltage and current waveforms of the inductor taken in the laboratory are then compared with those computed via the PSIM circuit simulator. PSIM is a simulation software designed for power electronics, motor control, and dynamic system simulation.

Salas, R. A.; Pleite, J.

2010-05-01

364

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

365

A computational model for epidural electrical stimulation of spinal sensorimotor circuits.  

PubMed

Epidural electrical stimulation (EES) of lumbosacral segments can restore a range of movements after spinal cord injury. However, the mechanisms and neural structures through which EES facilitates movement execution remain unclear. Here, we designed a computational model and performed in vivo experiments to investigate the type of fibers, neurons, and circuits recruited in response to EES. We first developed a realistic finite element computer model of rat lumbosacral segments to identify the currents generated by EES. To evaluate the impact of these currents on sensorimotor circuits, we coupled this model with an anatomically realistic axon-cable model of motoneurons, interneurons, and myelinated afferent fibers for antagonistic ankle muscles. Comparisons between computer simulations and experiments revealed the ability of the model to predict EES-evoked motor responses over multiple intensities and locations. Analysis of the recruited neural structures revealed the lack of direct influence of EES on motoneurons and interneurons. Simulations and pharmacological experiments demonstrated that EES engages spinal circuits trans-synaptically through the recruitment of myelinated afferent fibers. The model also predicted the capacity of spatially distinct EES to modulate side-specific limb movements and, to a lesser extent, extension versus flexion. These predictions were confirmed during standing and walking enabled by EES in spinal rats. These combined results provide a mechanistic framework for the design of spinal neuroprosthetic systems to improve standing and walking after neurological disorders. PMID:24305828

Capogrosso, Marco; Wenger, Nikolaus; Raspopovic, Stanisa; Musienko, Pavel; Beauparlant, Janine; Bassi Luciani, Lorenzo; Courtine, Grégoire; Micera, Silvestro

2013-12-01

366

Total dose and dose rate models for bipolar transistors in circuit simulation.  

SciTech Connect

The objective of this work is to develop a model for total dose effects in bipolar junction transistors for use in circuit simulation. The components of the model are an electrical model of device performance that includes the effects of trapped charge on device behavior, and a model that calculates the trapped charge densities in a specific device structure as a function of radiation dose and dose rate. Simulations based on this model are found to agree well with measurements on a number of devices for which data are available.

Campbell, Phillip Montgomery; Wix, Steven D.

2013-05-01

367

Modeling and magnetic measurements of TNK synchrotron radiation source magnets  

NASA Astrophysics Data System (ADS)

The TNK synchrotron radiation source is being built by Budker Institute of Nuclear Physics on the base of Lukin State Research Institute of Physical Problems. Magnetic system for the storage ring of TNK synchrotron radiation source was produced at the BINP. It consists of 6 superperiods and includes 24 dipole magnets, 72 quadrupole lenses, 36 sextupole lenses and 12 octupole lenses.The storage ring will operate in a wide range of energies—from 450 to 2200 MeV—which corresponds to 0.3-1.5 T magnetic field in dipole magnets. Dipole magnets have H-shape solid yokes from Armco iron with a curved form. Dipole gap is 42 mm and yoke straight length is 1447 mm. The results of 3D magnetic field modeling executed by means of Mermaid 3D are presented. All dipole magnets were magnetically measured by special Hall probe measurement system developed in BINP. The results of magnetic measurements and modeling are compared and analyzed.

Belokrinitsky, S.; Churkin, I.; Oleynik, A.; Pekshev, D.; Philipchenko, A.; Rouvinsky, I.; Steshov, A.; Ushakov, V.

2009-05-01

368

Magnetic properties modeling of soft magnetic composite materials using two-dimensional vector hybrid hysteresis model  

NASA Astrophysics Data System (ADS)

A 2-D vector hybrid hysteresis model for a soft magnetic composite (SMC) material is established, which is combined with classical Preisach model and Stoner-Wohlfarth (S-W) model. The rotational magnetic properties of SMC materials were studied using the vector model, and the computed results were compared with the experimental measurement. It is shown that the vector hybrid model can effectively simulate the rotational magnetic properties under low magnetization fields.

Li, Dandan; Liu, Fugui; Li, Yongjian; Zhao, Zhigang; Zhang, Changgeng; Yang, Qingxin

2014-05-01

369

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

370

Modeling two-dimensional magnetic domain patterns  

Microsoft Academic Search

Two-dimensional magnetic garnets exhibit complex and fascinating magnetic domain structures, like stripes, labyrinths, cells, and mixed states of stripes and cells. These patterns do change in a reversible way when the intensity of an externally applied magnetic field is varied. The main objective of this contribution is to present the results of a model that yields a rich pattern structure

J. R. Iglesias; S. Gonçalves; O. A. Nagel; Miguel Kiwi

2002-01-01

371

A Demonstration Model of Magnetic Resonance  

ERIC Educational Resources Information Center

Describes a simple and inexpensive model to demonstrate the pulsed magnetic resonance phenomenon. Gives the details of construction of the device which can provide a direct demonstration of the precessional motion of a magnetic moment in a steady magnetic field. (Author/GS)

Sandhu, H. S.; Peemoeller, H.

1974-01-01

372

Theoretical analysis of microwave and millimeter wave integrated circuits based on magnetic films  

NASA Astrophysics Data System (ADS)

A full modal analysis is used to study the dispersion characteristics of microstrip lines periodically loaded with crossing strips in a stratified uniaxially anisotropic medium. Dyadic Green's functions in the spectral domain for the multilayered medium in conjunction with the vector Fourier transform (VFT) are used to formulate a coupled set of vector integral equations for the current distribution on the signal line and the crossing strips. Galerkin's procedure is applied to derive the eigenvalue equation for the propagation constant. The effect of anisotropy for both open and shielded structures on the stopband properties is investigated. The input impedance of a microstrip antenna consisting of two circular microstrip disks in a stacked configuration driven by a coaxial probe is investigated. A rigorous analysis is performed using a dyadic Green's function formulation where the mixed boundary value problem is reduced to a set of coupled vector integral equations using the vector Hankel transform. Galerkin's method is employed in the spectral domain where two sets of disk current expansions are used. One set is based on the complete set of orthogonal modes of the magnetic cavity, and the other employs Chebyshev polynomials with the proper edge condition for the disk currents. An additional term is added to the disk current expansion to properly model the current in the vicinity of the probe/disk junction.

Kong, J. A.

1991-11-01

373

Space Mapping Optimization of the Magnetic Circuit of Electrical Machines Including Local Material Degradation  

Microsoft Academic Search

Production processes like cutting, performed on electrical steel laminations, influence their magnetic properties locally. Since the magnetic design of electrical machines does not take this effect into account accurately, the design may be suboptimal. Therefore, the need exists to develop a numerical procedure which is capable of optimizing electrical devices, taking into account the local material degradation and featuring high

Guillaume Crevecoeur; Luc Dupr; Rik Van de Walle

2007-01-01

374

A circuital approach to estimate the magnetic field reduction of nonferrous metal shields  

Microsoft Academic Search

The reduction of magnetic fields is a topic of concern to the electric utility industry and the electromagnetic compatibility community. One technique to reduce the magnetic fields is to use metal plates and enclosures for shielding, in addition, knowledge or the loading effect of a conducting structure in close proximity to power cables is needed for estimating power loss. Until

William M. Frix; George G. Karady

1997-01-01

375

Hybrid 0-D,1-D, and 2-D model of helical explosive-driven magnetic flux compression generator  

Microsoft Academic Search

A hybrid code model of the Sandia National Laboratories' model 632 is described is introduced. A very large explosive driven magnetic flux compression generator. This involves the use of two codes. The first is a coupled 0-D equivalent circuit model and 1-D magnetohydrodynamic computation. The second is the 2-D materials response code, CSQ. This is used to obtain an equivalent

T. J. Burgess

1985-01-01

376

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

377

Equivalent Circuit Modeling for Carbon Nanotube Schottky Barrier Modulation in Polarized Gases  

NASA Technical Reports Server (NTRS)

We study the carbon nanotube Schottky barrier at the metallic electrode interface in polarized gases using an equivalent circuit model. The gas-nanotube interaction is often weak and very little charge transfer is expected [l]. This is the case with'oxygen, but the gas-electrode interaction is appreciable and makes the oxygen molecules negatively charged. In the closed circuit condition, screening positive charges appear in the nanotube as well as in the electrode, and the Schottky barrier is modulated due to the resultant electrostatic effects [2]. In the case of ammonia, both the gas-nanotube and gas-electrode interactions are weak, but the Schottky barrier can still be modulated since the molecules are polarized and align in the preferred orientation within the gap between the electrode and nanotube in the open circuit condition (dipole layer formation). In the closed circuit condition, an electric field appears in the gap and strengthens or weakens the preferred dipole alignment reflecting the nanotube Fermi level. The modulation is visible when the nanotube depletion mode is involved, and the required dipole density is as low as 2 x 10(exp 13) dipoles/sq cm, which is quite feasible experimentally,

Yamada, Toshishige

2005-01-01

378

Temperature-Aware NBTI Modeling and the Impact of Standby Leakage Reduction Techniques on Circuit Performance Degradation  

Microsoft Academic Search

As technology scales, Negative Bias Temperature Instability (NBTI), which causes temporal performance degradation in digital circuits by affecting PMOS threshold voltage, is emerging as one of the major circuit reliability concerns. In this paper, we first investigate the impact of NBTI on PMOS devices and propose a temporal performance degradation model that considers the temperature variation between active and standby

Yu Wang; Hong Luo; Ku He; Rong Luo; Huazhong Yang; Yuan Xie

2011-01-01

379

Vibration suppression of scale model of railway carbody with piezoelectric elements: a study focused on designing shunt circuits  

Microsoft Academic Search

The goal of this study is to reduce the bending vibration of railway vehicles by applying a vibration suppression technique. The technique utilizes piezoelectric elements that are electrically shunted by an external circuit. This paper presents an investigation by using a scale model of a Shinkansen vehicle with a length of about 5m, mainly focused on implementation of shunt circuits.

Tadao Takigami; Takahiro Tomioka

2005-01-01

380

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

381

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

PubMed Central

Recent studies have suggested that autocrine 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. Under certain conditions, the model spontaneously evolves into a state wherein sustained signaling is spatially localized on smaller than cell dimension, conferring a polarity to the otherwise nonpolar model cell. Conditions of a sufficiently large rate of autocrine EGFR ligand release and of a sufficiently small exogenous ligand concentration are qualitatively consistent with experimental observations of EGFR-mediated migration. Thus, computational analysis supports the concept that autocrine EGFR signaling circuits could play a role in helping generate and/or maintain an intrinsic cell spatial polarity, possibly related to migration as well as tissue organization. We additionally offer particular suggestions for critical nodes in the EGFR signaling circuits governing this self-organization capability.

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

2004-01-01

382

Reconfigurable Special Test Circuit of physics-based IGBT models parameter extraction  

NASA Astrophysics Data System (ADS)

Physics-based models of power electronic devices are the most accurate for circuit simulation purposes. However, many parameters of such models are related to device physics and structure and are not directly available for the user. The IGBT is still the most used power semiconductor device for applications at medium power and frequency ranges, due to its good compromise between on-state loss, switching loss, and ease of control. This paper presents a procedure for extracting the most important parameters of the IGBT, with physical background and electrical measurements. The goal is to develop a deeply understanding of the device-structure and to simulate correctly both steady-state and transient period with any circuit simulation software without the IGBT model provided by the manufacturer. The method consists of seven test setups and seven algorithms for extracting 13 physical and structural parameters needed in most physics-based IGBT models; by using only one Reconfigurable Special Test Circuit in order to achieve the different test setups conditions.

Rodríguez, Marco A.; Claudio, Abraham; Cotorogea, Maria; González, Leobardo H.; Aguayo, Jesús

2010-11-01

383

Identifying roles for neurotransmission in circuit assembly: Insights gained from multiple model systems and experimental approaches  

PubMed Central

In the adult nervous system, chemical neurotransmission between neurons is essential for information processing. However, neurotransmission is also important for patterning circuits during development, but its precise roles have yet to be identified, and some remain highly debated. Here, we highlight viewpoints that have come to be widely accepted or still challenged. We discuss how distinct techniques and model systems employed to probe the developmental role of neurotransmission may reconcile disparate ideas. We underscore how the effects of perturbing neurotransmission during development vary with model systems, the stage of development when transmission is altered, the nature of the perturbation, and how connectivity is assessed. Based on findings in circuits with connectivity arranged in layers, we raise the possibility that there exist constraints in neuronal network design that limit the role of neurotransmission. We propose that activity-dependent mechanisms are effective in refining connectivity patterns only when inputs from different cells are close enough spatially to influence each other’s outcome.

Bleckert, Adam; Wong, Rachel O.L.

2014-01-01

384

Modelling nonlinearity in piezoceramic transducers: From equations to nonlinear equivalent circuits.  

PubMed

Quadratic nonlinear equations of a piezoelectric element under the assumptions of 1D vibration and weak nonlinearity are derived by the perturbation theory. It is shown that the nonlinear response can be represented by controlled sources that are added to the classical hexapole used to model piezoelectric ultrasonic transducers. As a consequence, equivalent electrical circuits can be used to predict the nonlinear response of a transducer taking into account the acoustic loads on the rear and front faces. A generalisation of nonlinear equivalent electrical circuits to cases including passive layers and propagation media is then proposed. Experimental results, in terms of second harmonic generation, on a coupled resonator are compared to theoretical calculations from the proposed model. PMID:20855096

Parenthoine, D; Tran-Huu-Hue, L-P; Haumesser, L; Vander Meulen, F; Lematre, M; Lethiecq, M

2011-02-01

385

Modifications and Modeling of the Fission Surface Power Primary Test Circuit (FSP-PTC)  

NASA Technical Reports Server (NTRS)

An actively pumped alkali metal flow circuit, designed and fabricated at the NASA Marshall Space Flight Center, underwent a range of tests at MSFC in early 2007. During this period, system transient responses and the performance of the liquid metal pump were evaluated. In May of2007, the circuit was drained and cleaned to prepare for multiple modifications: the addition of larger upper and lower reservoirs, the installation of an annular linear induction pump (ALIP), and the inclusion of a closeable orifice in the test section. Performance of the ALIP, provided by Idaho National Laboratory (INL), will be evaluated when testing resumes. Data from the first round of testing has been used to refine the working system model, developed using the Generalized Fluid System Simulation Program (GFSSP). This paper covers the modifications of the FSP-PTC and the updated GFSSP system model.

Garber, Anne E.

2008-01-01

386

Development of an equivalent-circuit model for the lithium/iodine battery  

NASA Astrophysics Data System (ADS)

The lithium/iodine battery is the most widely used power source for implantable cardiac pacemakers. While the average power demands of pacemakers are very low, the instantaneous power requirements can challenge the capabilities of this high impedance battery. Thus, there is a need to predict the transient-response behavior of new battery designs. Impedance spectroscopy was used to characterize the behavior of a variety of cell designs as a function of cell design, depth-of-discharge, and current density. An equivalent-circuit model was developed in terms of the physical elements which contribute to electrical resistance, capacitance, and electrochemical polarization. The transient-response predicted by this simple equivalent-circuit model was compared to pulse data from actual batteries and found to be in excellent agreement.

Schmidt, Craig L.; Skarstad, Paul M.

387

Accurate Cold-Test Model of Helical TWT Slow-Wave Circuits  

NASA Technical Reports Server (NTRS)

Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional (3-D) electromagnetic computer code, MAxwell's equations by the Finite Integration Algorithm (MAFIA). Cold-test parameters have been calculated for several helical traveLing-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes and material properties consistent with the actual circuits. The cold-test data from this helical model can be used as input into large-signal helical TWT interaction codes making It possible, for the first time, to design complete TWT via computer simulation.

Kory, Carol L.; Dayton, James A., Jr.

1998-01-01

388

Accurate Cold-Test Model of Helical TWT Slow-Wave Circuits  

NASA Technical Reports Server (NTRS)

Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional electromagnetic computer code, MAFIA. Cold-test parameters have been calculated for several helical traveling-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes and material properties consistent with the actual circuits. The cold-test data from this helical model can be used as input into large-signal helical TWT interaction codes making it possible, for the first time, to design a complete TWT via computer simulation.

Kory, Carol L.; Dayton, James A., Jr.

1997-01-01

389

Accurate Cold-Test Model of Helical TWT Slow-Wave Circuits  

NASA Technical Reports Server (NTRS)

Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional (3-D) electromagnetic computer code, MAFIA. Cold-test parameters have been calculated for several helical traveling-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes and material properties consistent with the actual circuits. The cold-test data from this helical model can be used as input into large-signal helical TWT interaction codes making it possible, for the first time, to design a complete TWT via computer simulation.

Kory, Carol L.; Dayton, J. A., Jr.

1998-01-01

390

Circuit models and three-dimensional electromagnetic simulations of a 1-MA linear transformer driver stage  

NASA Astrophysics Data System (ADS)

A 3D fully electromagnetic (EM) model of the principal pulsed-power components of a high-current linear transformer driver (LTD) has been developed. LTD systems are a relatively new modular and compact pulsed-power technology based on high-energy density capacitors and low-inductance switches located within a linear-induction cavity. We model 1-MA, 100-kV, 100-ns rise-time LTD cavities [A. A. Kim , Phys. Rev. ST Accel. Beams 12, 050402 (2009)PRABFM1098-440210.1103/PhysRevSTAB.12.050402] which can be used to drive z-pinch and material dynamics experiments. The model simulates the generation and propagation of electromagnetic power from individual capacitors and triggered gas switches to a radially symmetric output line. Multiple cavities, combined to provide voltage addition, drive a water-filled coaxial transmission line. A 3D fully EM model of a single 1-MA 100-kV LTD cavity driving a simple resistive load is presented and compared to electrical measurements. A new model of the current loss through the ferromagnetic cores is developed for use both in circuit representations of an LTD cavity and in the 3D EM simulations. Good agreement between the measured core current, a simple circuit model, and the 3D simulation model is obtained. A 3D EM model of an idealized ten-cavity LTD accelerator is also developed. The model results demonstrate efficient voltage addition when driving a matched impedance load, in good agreement with an idealized circuit model.

Rose, D. V.; Miller, C. L.; Welch, D. R.; Clark, R. E.; Madrid, E. A.; Mostrom, C. B.; Stygar, W. A.; Lechien, K. R.; Mazarakis, M. A.; Langston, W. L.; Porter, J. L.; Woodworth, J. R.

2010-09-01

391

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

392

Magnetic transcranial stimulation at intensities below active motor threshold activates intracortical inhibitory circuits  

Microsoft Academic Search

A magnetic transcranial conditioning stimulus given over the motor cortex at intensities below threshold for obtaining electromyographical\\u000a (EMG) responses in active hand muscles can suppress responses evoked in the same muscles at rest by a suprathreshold magnetic\\u000a test stimulus given 1–5 ms later. In order to define the mechanism of this inhibitory effect, we recorded descending volleys\\u000a produced by single

V. Di Lazzaro; D. Restuccia; A. Oliviero; P. Profice; L. Ferrara; A. Insola; P. Mazzone; P. Tonali; J. C. Rothwell

1998-01-01

393

Accurate cold-test model of helical TWT slow-wave circuits  

Microsoft Academic Search

Recently, a method has been established to accurately calculate cold-test data for helical slow-wave structures using the three-dimensional (3-D) electromagnetic computer code, MAFIA. Cold-test parameters have been calculated for several helical traveling-wave tube (TWT) slow-wave circuits possessing various support rod configurations, and results are presented here showing excellent agreement with experiment. The helical models include tape thickness, dielectric support shapes

Carol L. Kory; James A. Dayton

1998-01-01

394

Equivalent circuit modelling of p-i-n photodiodes for 40 Gb\\/s receivers  

Microsoft Academic Search

We have described a back-illuminated photodetector with an 0.62 A\\/W responsivity, a typical dark current of 3 nA at -5 V bias, a failure rate of less than 1 FIT at 40°C, and a bandwidth (into a 50 ohm load) as high as 39 GHz. By inserting a tunnelling element into an otherwise standard equivalent circuit model, we have shown

A. H. Steinbach; I. Penn; N. Chokshi; D. Martin; K. Slomkowski; W. Baun; N. Agrawal; R. Ben-Michael; M. A. Itzler

2002-01-01

395

A mixed-level modeling and simulation for digital MOS integrated circuits  

Microsoft Academic Search

This dissertation deals with techniques of a fast and accurate simulation tool for digital integrated circuits composed of metal-oxide-semiconductor (MOS) transistors. The demand for high performance and accuracy of digital logic simulation has led to the development of a logic simulator that is capable of handling two levels of models: gate and switch. This mixed-level approach attempts to high performance,

Kong

1989-01-01

396

Circuit noise evaluation by Padé approximation based model-reduction techniques  

Microsoft Academic Search

This paper introduces a new circuit noise analysis and modeling method. The noise analysis method computes an analytic expression of frequency, in rational form, which represents the Pad\\\\'e approximation of the noise power spectral density. The approximation can be carried out efficiently, to the required accuracy, using a variant of the PVL~\\\\cite{FelF95} or MPVL~\\\\cite{FelF95b} algorithms. The new method is significantly

Peter Feldmann; Roland W. Freund

1997-01-01

397

Simulation model for drainage protection of earth-return circuits laid in stray currents area  

Microsoft Academic Search

Proper design of drainage protection against stray currents requires the knowledge of current and potential distribution\\u000a along the rails of the d.c. railway system and the installation to be protected (cable, pipeline, etc.). Usually, a calculation\\u000a model is used in which these earth-return circuits are treated as separate. In reality, the protected structure and the rail\\u000a can be placed close

W. Machczyñski

2002-01-01

398

The Circuit Theory Behind Coupled-Mode Magnetic Resonance-Based Wireless Power Transmission  

PubMed Central

Inductive coupling is a viable scheme to wirelessly energize devices with a wide range of power requirements from nanowatts in radio frequency identification tags to milliwatts in implantable microelectronic devices, watts in mobile electronics, and kilowatts in electric cars. Several analytical methods for estimating the power transfer efficiency (PTE) across inductive power transmission links have been devised based on circuit and electromagnetic theories by electrical engineers and physicists, respectively. However, a direct side-by-side comparison between these two approaches is lacking. Here, we have analyzed the PTE of a pair of capacitively loaded inductors via reflected load theory (RLT) and compared it with a method known as coupled-mode theory (CMT). We have also derived PTE equations for multiple capacitively loaded inductors based on both RLT and CMT. We have proven that both methods basically result in the same set of equations in steady state and either method can be applied for short- or midrange coupling conditions. We have verified the accuracy of both methods through measurements, and also analyzed the transient response of a pair of capacitively loaded inductors. Our analysis shows that the CMT is only applicable to coils with high quality factor (Q) and large coupling distance. It simplifies the analysis by reducing the order of the differential equations by half compared to the circuit theory.

Kiani, Mehdi; Ghovanloo, Maysam

2014-01-01

399

Finite element analysis of a ferrite-core inductor with direct current bias current using an equivalent-circuit model of dynamic hysteretic properties  

NASA Astrophysics Data System (ADS)

The finite element (FE) modeling of a ferrite-core device is discussed. Measured properties of Ni-Zn ferrite ring cores show that even though the AC ferrite property is similar to that caused by the eddy-current field, the FE eddy-current analysis using an equivalent electrical conductivity cannot, in practice, represent the AC property. An equivalent-circuit model which describes AC/DC ferrite properties is applied to FE magnetic field analysis of a ferrite-core inductor. The simulated AC property with/without DC bias agrees with the measured one.

Ito, S.; Mifune, T.; Matsuo, T.; Suzuki, M.; Kawano, K.

2014-05-01

400

Circuit modeling of the transmissivity of stacked two-dimensional metallic meshes.  

PubMed

This paper presents a simple analytical circuit-like model to study the transmission of electromagnetic waves through stacked two-dimensional (2-D) conducting meshes. When possible the application of this methodology is very convenient since it provides a straightforward rationale to understand the physical mechanisms behind measured and computed transmission spectra of complex geometries. Also, the disposal of closed-form expressions for the circuit parameters makes the computation effort required by this approach almost negligible. The model is tested by proper comparison with previously obtained numerical and experimental results. The experimental results are explained in terms of the behavior of a finite number of strongly coupled Fabry-Pérot resonators. The number of transmission peaks within a transmission band is equal to the number of resonators. The approximate resonance frequencies of the first and last transmission peaks are obtained from the analysis of an infinite structure of periodically stacked resonators, along with the analytical expressions for the lower and upper limits of the pass-band based on the circuit model. PMID:20588460

Kaipa, Chandra S R; Yakovlev, Alexander B; Medina, Francisco; Mesa, Francisco; Butler, Celia A M; Hibbins, Alastair P

2010-06-21

401

Use of a 1-dimensional heat flow model to calculate circuit board thermal resistance for use in the MQUAD(R) package thermal model  

Microsoft Academic Search

An analytical 1D heat flow model for the area of a circuit board outside the package footprint is described. The model is capable of dealing with infinite and finite boards. Thermal profiles predicted by this agree well with measured values for a range of circuit boards. The thermal resistance calculated by the 1D model also agrees well with values resulting

Peter Robinson; Brian Mravic

1996-01-01

402

Massive star models with magnetic braking  

NASA Astrophysics Data System (ADS)

Context. Magnetic fields at the surface of a few early-type stars have been directly detected. These fields have magnitudes between a few hundred G up to a few kG. In one case, evidence of magnetic braking has been found. Aims: We investigate the effects of magnetic braking on the evolution of rotating (?ini = 200 km s-1) × 10 M_? stellar models at solar metallicity during the main-sequence (MS) phase. Methods: The magnetic braking process is included in our stellar models according to the formalism deduced from 2D MHD simulations of magnetic wind confinement by ud-Doula and co-workers. Various assumptions are made regarding both the magnitude of the magnetic field and of the efficiency of the angular momentum transport mechanisms in the stellar interior. Results: When magnetic braking occurs in models with differential rotation, a strong and rapid mixing is obtained at the surface accompanied by a rapid decrease in the surface velocity. Such a process might account for some MS stars showing strong mixing and low surface velocities. When solid-body rotation is imposed in the interior, the star is slowed down so rapidly that surface enrichments are smaller than in similar models with no magnetic braking. In both kinds of models (differentially or uniformly rotating), magnetic braking due to a field of a few 100 G significantly reduces the angular momentum of the core during the MS phase. This reduction is much greater in solid-body rotating models.

Meynet, G.; Eggenberger, P.; Maeder, A.

2011-01-01

403

Simulation of SLF Interrupting Performance for SF6 Gas Circuit Breaker based on Serially Connected 3 Arc Models  

NASA Astrophysics Data System (ADS)

This paper shows the simulation of SLF interrupting performances for SF6 gas circuit breakers. From the measurements using 300kV-SF6 gas model circuit breakers, it was shown that the extinction peak voltages were varying with arcing times. But, the current values at the extinction peak were the same. To simulate the SLF interrupting performances for the circuit breakers, serially connected 3 arc models were used. Cassie arc model and two Mayr arc models were serially connected. In this arc model, the Cassie model simulates the high current arc. One of the Mayr arc model (Mayr model 1) simulates the arc around the voltage extinction peak. And the other Mayr arc model simulates the arc around current zero. In this model, arc voltage of the Cassie model and arc power loss of the Mayr model 1 are only estimated from the experiments. It was good agreement with the measurements and simulations.

Koshizuka, Tadashi; Shinkai, Takeshi; Udagawa, Keisuke; Kawano, Hiromichi

404

Quantitative model of the magnetospheric magnetic field  

Microsoft Academic Search

Quantitative representations of the magnetic fields associated with the magnetopause currents and the distributed currents (tail and quiet time ring currents) have been developed. These fields are used together with a dipole representation of the main field of the earth to model the total vector magnetospheric magnetic field. The model is based on quiet time data averaged over all 'tilt

W. P. Olson; K. A. Pfitzer

1974-01-01

405

Dipole Modeling of Magnetic Flux Leakage  

Microsoft Academic Search

In this paper, we present an analytical model to represent the 3-D magnetic flux leakage (MFL) field due to the occurrence of a surface-breaking defect in a ferromagnetic specimen. This situation is frequently encountered in the nondestructive evaluation (NDE) of energy pipelines using the MFL technique. The model is derived from first principles, and utilizes the concept of dipolar magnetic

Sushant M. Dutta; Fathi H. Ghorbel; Roderic K. Stanley

2009-01-01

406

Simulation of arc-electrode interaction using sheath modelling in SF6 circuit-breakers  

NASA Astrophysics Data System (ADS)

The transition layer, or sheath, located at the interface between the electrode and the electric arc plasma in circuit-breaker arcs is modelled and integrated into software for the simulation of arcs. The sheath model includes the equation of the continuity of electrons, the generalized Ohm's law and the equation of conservation of total energy. The latter equation takes into account Joule heating, the radiation from the arc and phenomena on the surface of the electrode such as thermionic and radiative cooling by thermal emission. The resulting arc model can predict electrode and arc temperatures simultaneously.

Maruzewski, P.; Martin, A.; Reggio, M.; Trépanier, J.-Y.

2002-05-01

407

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

408

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

409

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

410

SEMICONDUCTOR INTEGRATED CIRCUITS: Scalable modeling and comparison for spiral inductors using enhanced 1-? and 2-? topologies  

NASA Astrophysics Data System (ADS)

Two different scalable models developed based on enhanced 1-? and 2-? topologies are presented for on-chip spiral inductor modeling. All elements used in the two topologies for accurately predicting the characteristics of spiral inductors at radio frequencies are constructed in geometry-dependent equations for scalable modeling. Then a comparison between the 1-? and 2-? scalable models is made from the following aspects: the complexity of equivalent circuit models and parameter-extraction procedures, scalable rules and the accuracy of scalable models. The two scalable models are further verified by the excellent match between the measured and simulated results on extracted parameters up to self-resonant frequency (SRF) for a set of spiral inductors with different L, R and N, which are fabricated by employing 0.18-?m 1P6M RF CMOS technology.

Huanhuan, Zou; Lingling, Sun; Jincai, Wen; Jun, Liu

2010-05-01

411

Quantitative modeling and optimization of magnetic tweezers.  

PubMed

Magnetic tweezers are a powerful tool to manipulate single DNA or RNA molecules and to study nucleic acid-protein interactions in real time. Here, we have modeled the magnetic fields of permanent magnets in magnetic tweezers and computed the forces exerted on superparamagnetic beads from first principles. For simple, symmetric geometries the magnetic fields can be calculated semianalytically using the Biot-Savart law. For complicated geometries and in the presence of an iron yoke, we employ a finite-element three-dimensional PDE solver to numerically solve the magnetostatic problem. The theoretical predictions are in quantitative agreement with direct Hall-probe measurements of the magnetic field and with measurements of the force exerted on DNA-tethered beads. Using these predictive theories, we systematically explore the effects of magnet alignment, magnet spacing, magnet size, and of adding an iron yoke to the magnets on the forces that can be exerted on tethered particles. We find that the optimal configuration for maximal stretching forces is a vertically aligned pair of magnets, with a minimal gap between the magnets and minimal flow cell thickness. Following these principles, we present a configuration that allows one to apply > or = 40 pN stretching forces on approximately 1-microm tethered beads. PMID:19527664

Lipfert, Jan; Hao, Xiaomin; Dekker, Nynke H

2009-06-17

412

A thermodynamically consistent model for magnetic hysteresis  

NASA Astrophysics Data System (ADS)

A phenomenological constitutive model is presented to describe the magnetization curve within the context of thermodynamics. Due to the phenomenological analogy between the magnetic hysteresis and the stress hysteresis, the basic structure of the proposed model comes from rate-dependent plasticity in continuum mechanics, namely viscoplasticity. The total magnetic flux density is assumed to be the sum of reversible and irreversible parts. The model introduces the evolution laws of two internal state variables to incorporate the effect of the ever-changing internal microstructure on the current state. The conception originated from viscoplasticity enables the frequency dependence of the hysteresis curve to be modeled.

Ho, Kwangsoo

2014-05-01

413

Optimization of the magnetic circuit of the homopolar inductor machine with non-overlapping concentrated windings  

Microsoft Academic Search

The present work considers issues about optimization of the tooth zone of homopolar inductor generator with non-overlapping concentrated coils. The recommendations for the choice of optimal parameters of the tooth zone are made on the basis of the analysis of magnetic field in the machine's cross-section. The results of the experiment data of the inductor generator's test sample with the

Nikolaj Levin; Svetlana Orlova; Vladislav Pugachov; Leonids Ribickis

2010-01-01

414

Nonlinear model of the parasitic backward-wave oscillation in the traveling wave tube under periodic permanent magnetic focusing  

Microsoft Academic Search

We present a mathematical nonlinear model of the parasitic backward-wave oscillation in the generic helix TWT under permanent periodic magnetic (PPM) focusing. The model accounts for the interaction of the electromagnetic wave existing on the helix slow-wave circuit and the electron beam alternating rotation in the PPM focusing field. We obtain an equation system, which permits us to find the

Eugene D. Belyavskiy; Sergei N. Khotiaintsev

2004-01-01

415

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

416

Magnetically nonlinear dynamic model of synchronous motor with permanent magnets  

NASA Astrophysics Data System (ADS)

This paper deals with a magnetically nonlinear two-axis dynamic model of a permanent magnet synchronous motor (PMSM). The geometrical and material properties of iron core and permanent magnets, the effects of winding distribution, saturation, cross-saturation and slotting effects are, for the first time, simultaneously accounted for in a single two-axis dynamic model of a three-phase PMSM. They are accounted for by current- and position-dependent characteristics of flux linkages. These characteristics can be determined either experimentally or by the finite element (FE) computations. The results obtained by the proposed dynamic model show a very good agreement with the measured ones and those obtained by the FE computation.

Hadžiselimovi?, Miralem; Štumberger, Gorazd; Štumberger, Bojan; Zagradišnik, Ivan

2007-09-01

417

Investigation on Controlling Techniques of Moving Contact Behaviors for Vacuum Circuit Breaker Based on Fuzzy Control  

Microsoft Academic Search

To improve the switching property of the vacuum circuit breaker, a scheme of position feedback control for permanent magnetic actuator vacuum circuit breaker is presented based on fuzzy control. An adaptive fuzzy controller is designed. With Matlab fuzzy and simulink software package, a model is built to simulate the control scheme. The result indicates that the permanent magnetic actuator can

Li Tian-Hui; Fang Chun-en; Li Wei; Zhou Li-li

2010-01-01

418

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

419

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

420

Modeling two-dimensional magnetic domain patterns  

Microsoft Academic Search

Two-dimensional magnetic garnets exhibit complex and fascinating magnetic\\u000adomain structures, like stripes, labyrinths, cells and mixed states of stripes\\u000aand cells. These patterns do change in a reversible way when the intensity of\\u000aan externally applied magnetic field is varied. The main objective of this\\u000acontribution is to present the results of a model that yields a rich pattern\\u000astructure

J. R. Iglesias; S. Goncalves; O. A. Nagel; Miguel Kiwi

2002-01-01

421

Analysis of multicrystalline silicon solar cells by modified 3-diode equivalent circuit model taking leakage current through periphery into consideration  

Microsoft Academic Search

We proposed a modified 3-diode equivalent circuit model for analysis of multicrystalline silicon (Mc-Si) solar cells. By using this equivalent circuit model, we can precisely evaluate the characteristics of Mc-Si solar cells taking the influence of grain boundaries and large leakage current through the peripheries into consideration and extract electrical properties. The calculated value of current-voltage characteristics for small size

Kensuke Nishioka; Nobuhiro Sakitani; Yukiharu Uraoka; Takashi Fuyuki

2007-01-01

422

An Analysis on Synchronous Reluctance Motors by Use of Magnetic Circuit  

NASA Astrophysics Data System (ADS)

The synchronous reluctance motors operated by a PWM inverter can be designed for the maximum saliency ratio (Ld/Lq). The saliency ratio is the most important parameter for achieving a high torque capability, high power factor and wide constant-power speed range. Generally, flux guides for the d-axis and flux barriers for the q-axis are provided to achieve a high Ld and low Lq, respectively, in order to maximize the saliency ratio. In this paper, the optimal shape and thickness of the flux barriers are investigated analytically. It is also demonstrated that the optimal rotor flux barrier shape can be expressed as the contour line of the function that shows the magnetic potential in a uniform material rotor. The effects of the magnetic resistance of the stator and the gap are also analyzed.

Kondo, Minoru

423

Transport Properties of Soils and Spectral Electrical Response: Equivalent Circuit Models  

NASA Astrophysics Data System (ADS)

Non-invasive prediction of hydraulic properties of soils (hydraulic conductivity, porosity, and degree of saturation) from surface measurement techniques as provided by geophysical methods is appealing to geoscientists involved in groundwater and pollution control problems. There is the need, however, to understand how the hydraulic properties of soil influence their spectral electrical response (SER). Laboratory measurements of the spectral electrical response of over 30 soil samples taken from different sites across North Carolina were performed within the frequency range from 0.01 Hz to 10 kHz. The hydraulic conductivity, porosity, and moisture content of each soil sample were measured. Both the moisture content and the degree of compaction were controlled for each soil sample to simulate field conditions. The SER measurements are used to estimate the hydraulic conductivity and porosity of soils. The SER of a soil is modeled as a heterogeneous multiphase system using an equivalent circuit model. The intrinsic parameters, which describe the response of the model, are retrieved by an inversion scheme and are used in empirical regression models to predict the hydraulic conductivity and porosity. Multiple regression analyses suggest that the porosity and permeability can be well predicted by the parameters of the equivalent circuit model. Such direct relationships between parameters characterizing the spectral electrical response of soils and their hydraulic properties may provide versatile non-invasive methodology of obtaining hydraulic conductivity and porosity of soils using geophysical measurements.

Boadu, F. K.

2002-05-01

424

Extraction of battery parameters using a multi-objective genetic algorithm with a non-linear circuit model  

NASA Astrophysics Data System (ADS)

There is need for a battery model that can accurately describe the battery performance for an electrical system, such as the electric drive train of electric vehicles. In this paper, both linear and non-linear equivalent circuit models (ECM) are employed as a means of extracting the battery parameters that can be used to model the performance of a battery. The linear and non-linear equivalent circuit models differ in the numbers of capacitance and resistance; the non-linear model has an added circuit; however their numerical characteristics are equivalent. A multi-objective genetic algorithm is employed to accurately extract the values of the battery model parameters. The battery model parameters are obtained for several existing industrial batteries as well as for two recently proposed high performance batteries. Once the model parameters are optimally determined, the results demonstrate that both linear and non-linear equivalent circuit models can predict with acceptable accuracy the performance of various batteries of different sizes, characteristics, capacities, and materials. However, the comparisons of results with catalog and experimental data shows that the predictions of results using the non-linear equivalent circuit model are slightly better than those predicted by the linear model, calculating voltages that are closer to the manufacturers’ values.

Malik, Aimun; Zhang, Zheming; Agarwal, Ramesh K.

425

A GLOBAL MAGNETIC TOPOLOGY MODEL FOR MAGNETIC CLOUDS. II  

SciTech Connect

In the present work, we extensively used our analytical approach to the global magnetic field topology of magnetic clouds (MCs), introduced in a previous paper, in order to show its potential and to study its physical consistency. The model assumes toroidal topology with a non-uniform (variable maximum radius) cross-section along them. Moreover, it has a non-force-free character and also includes the expansion of its cross-section. As is shown, the model allows us, first, to analyze MC magnetic structures-determining their physical parameters-with a variety of magnetic field shapes, and second, to reconstruct their relative orientation in the interplanetary medium from the observations obtained by several spacecraft. Therefore, multipoint spacecraft observations give the opportunity to infer the structure of this large-scale magnetic flux rope structure in the solar wind. For these tasks, we use data from Helios (A and B), STEREO (A and B), and Advanced Composition Explorer. We show that the proposed analytical model can explain quite well the topology of several MCs in the interplanetary medium and is a good starting point for understanding the physical mechanisms under these phenomena.

Hidalgo, M. A., E-mail: miguel.hidalgo@uah.es [Departamento de Fisica, Universidad de Alcala, Apartado 20, E-28871 Alcala de Henares, Madrid (Spain)

2013-04-01

426

A Global Magnetic Topology Model for Magnetic Clouds. I.  

NASA Astrophysics Data System (ADS)

We present an analytical approach to the global magnetic field topology of magnetic clouds (MCs) that considers them like close magnetic structures with torus geometry and with a non-uniform (variable maximum radius) cross section along them. Following our previous approach to the problem of MCs (Hidalgo 2003, 2011), we establish an intrinsic coordinate system for that topology, and then we analytically solve the Maxwell equations in terms of it. The purpose of the present work is to present this model, which will lead us to understand in a more realistic way the physical mechanisms inside MCs. The model has a non-force-free character and also takes into account the time evolution of the cross sections of the MCs in their movement through the interplanetary medium. In this first paper, we obtain the expressions for the components of the magnetic field and the plasma current density imposing a large mean radius of the torus, and imposing a circular cross section with a variable maximum radius. Eventually, we fit the model to data related to four well-known MCs measurements at 1 AU, (three of them with circular cross sections and without expansion, as it is deduced from the experimental data). We compare the results of this toroidal model with those obtained with our previous cylindrical circular cross section model, also with a non-force-free character.

Hidalgo, M. A.; Nieves-Chinchilla, T.

2012-04-01

427

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

428

Unified equivalent-circuit model of planar discontinuities suitable for field theory-based CAD and optimization of M(H)MIC's  

Microsoft Academic Search

Unified dynamic equivalent-circuit model for characterizing planar unbounded discontinuities is reported for use in the field-theory-based computer-aided design and optimization of high-frequency integrated circuits and structures such as monolithic and hybrid microwave integrated circuits (M(H)MIC's). The proposal of the circuit model is stemmed from a new scheme called the short-open calibration (SOC) technique. This SOC technique is directly accommodated in

Lei Zhu; Ke Wu

1999-01-01

429

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

430

A lumped-circuit model for the radiation impedance of a circular piston in a rigid baffle.  

PubMed

The radiation impedance of a piston transducer mounted in a rigid baffle has been widely addressed in the literature. The real and imaginary parts of the impedance are described by the first order Bessel and Struve functions, respectively. Although there are power series expansions for both functions, the analytic formulation of a lumped circuit is not trivial. In this paper, we present an empirical approach to the derivation of a lumped-circuit model for the radiation impedance expression, based on observations on the near-field behavior of stored kinetic and elastic energy. The field analysis is carried out using a finite element method model of the piston and surrounding fluid medium. We show that fluctuations in the real and imaginary components of the impedance can be modeled by series and shunt tank circuits, each of which shape a certain section of the impedance curve. Because the model is composed of lumped-circuit elements, it can be used in circuit simulators. Consequently, the proposed model is useful for the analysis of transducer front-end circuits. PMID:18986901

Bozkurt, Ayhan

2008-09-01

431

Impaired activity-dependent neural circuit assembly and refinement in autism spectrum disorder genetic models.  

PubMed

Early-use activity during circuit-specific critical periods refines brain circuitry by the coupled processes of eliminating inappropriate synapses and strengthening maintained synapses. We theorize these activity-dependent (A-D) developmental processes are specifically impaired in autism spectrum disorders (ASDs). ASD genetic models in both mouse and Drosophila have pioneered our insights into normal A-D neural circuit assembly and consolidation, and how these developmental mechanisms go awry in specific genetic conditions. The monogenic fragile X syndrome (FXS), a common cause of heritable ASD and intellectual disability, has been particularly well linked to defects in A-D critical period processes. The fragile X mental retardation protein (FMRP) is positively activity-regulated in expression and function, in turn regulates excitability and activity in a negative feedback loop, and appears to be required for the A-D remodeling of synaptic connectivity during early-use critical periods. The Drosophila FXS model has been shown to functionally conserve the roles of human FMRP in synaptogenesis, and has been centrally important in generating our current mechanistic understanding of the FXS disease state. Recent advances in Drosophila optogenetics, transgenic calcium reporters, highly-targeted transgenic drivers for individually-identified neurons, and a vastly improved connectome of the brain are now being combined to provide unparalleled opportunities to both manipulate and monitor A-D processes during critical period brain development in defined neural circuits. The field is now poised to exploit this new Drosophila transgenic toolbox for the systematic dissection of A-D mechanisms in normal versus ASD brain development, particularly utilizing the well-established Drosophila FXS disease model. PMID:24570656

Doll, Caleb A; Broadie, Kendal

2014-01-01

432

Impaired activity-dependent neural circuit assembly and refinement in autism spectrum disorder genetic models  

PubMed Central

Early-use activity during circuit-specific critical periods refines brain circuitry by the coupled processes of eliminating inappropriate synapses and strengthening maintained synapses. We theorize these activity-dependent (A-D) developmental processes are specifically impaired in autism spectrum disorders (ASDs). ASD genetic models in both mouse and Drosophila have pioneered our insights into normal A-D neural circuit assembly and consolidation, and how these developmental mechanisms go awry in specific genetic conditions. The monogenic fragile X syndrome (FXS), a common cause of heritable ASD and intellectual disability, has been particularly well linked to defects in A-D critical period processes. The fragile X mental retardation protein (FMRP) is positively activity-regulated in expression and function, in turn regulates excitability and activity in a negative feedback loop, and appears to be required for the A-D remodeling of synaptic connectivity during early-use critical periods. The Drosophila FXS model has been shown to functionally conserve the roles of human FMRP in synaptogenesis, and has been centrally important in generating our current mechanistic understanding of the FXS disease state. Recent advances in Drosophila optogenetics, transgenic calcium reporters, highly-targeted transgenic drivers for individually-identified neurons, and a vastly improved connectome of the brain are now being combined to provide unparalleled opportunities to both manipulate and monitor A-D processes during critical period brain development in defined neural circuits. The field is now poised to exploit this new Drosophila transgenic toolbox for the systematic dissection of A-D mechanisms in normal versus ASD brain development, particularly utilizing the well-established Drosophila FXS disease model.

Doll, Caleb A.; Broadie, Kendal

2014-01-01

433

Transcranial Magnetic Stimulation: Modelling and New Techniques.  

National Technical Information Service (NTIS)

The aim of this thesis was to develop physical understanding of magnetic stimulation and to build models that could provide new insights for utilizing the technique. For this purpose, two principal issues had to be addressed: (1) macroscopic electromagnet...

J. Ruohonen

1998-01-01

434

Measured 3D turbulent mixing in a small-scale circuit breaker model  

NASA Astrophysics Data System (ADS)

Turbulence plays a key role in several physical processes related to the interruption of current in a gas circuit breaker (GCB). In this paper we study one aspect, namely turbulent gas mixing in the heating volume of a small-scale 3D GCB model. Mixing is observed using a shadowgraphy setup; postprocessing extracts information on the time-varying velocity field. Discharges with two different current amplitudes were studied and their repeatability investigated. A measure of mixing completeness, the largest vortex area, was investigated. The experiments reported upon in this paper were done in air at atmospheric pressure.

Basse, Nils T.; Kissing, Christopher; Bini, Riccardo

2011-06-01

435

A mathematical model for the shape of wave-soldered joints on printed circuit boards  

NASA Astrophysics Data System (ADS)

The problem of automatic inspection of solder joints in Printed Circuit Boards by 3D machine vision, is addressed. To provide an appropriate theoretical background to its solution, a mathematical model for the geometric shape of a wide class of wave-soldered joints is elaborated. The formation of such joints is considered approximately as a static phenomenon and studied as a moving boundary constrained variational problem, leading to a general differential equation, which offers a satisfactory model of the joint's shape. The case of axisymmetric through-hole-soldered joints is studied in detail, by integrating numerically the corresponding equations in various cases. The use of the model for simulation of sensor data is illustrated and the possibilities of using the information provided by the model for the development of inspection algorithms, are discussed.

Kyritsis, A.; Tzanakis, C.

1993-08-01

436

Design and analysis of perfect terahertz metamaterial absorber by a novel dynamic circuit model.  

PubMed

Metamaterial terahertz absorbers composed of a frequency selective layer followed by a spacer and a metallic backplane have recently attracted great attention as a device to detect terahertz radiation. In this work, we present a quasistatic dynamic circuit model that can decently describe operational principle of metamaterial terahertz absorbers based on interference theory of reflected waves. The model comprises two series LC resonance components, one for resonance in frequency selective surface (FSS) and another for resonance inside the spacer. Absorption frequency is dominantly determined by the LC of FSS while the spacer LC changes slightly the magnitude and frequency of absorption. This model fits perfectly for both simulated and experimental data. By using this model, we study our designed absorber and we analyze the effect of changing in spacer thickness and metal conductivity on absorption spectrum. PMID:23938496

Hokmabadi, Mohammad Parvinnezhad; Wilbert, David S; Kung, Patrick; Kim, Seongsin M

2013-07-15

437

SEMICONDUCTOR INTEGRATED CIRCUITS: Sigma-delta modulator modeling analysis and design  

NASA Astrophysics Data System (ADS)

This paper introduces a new method for SC sigma-delta modulator modeling. It studies the integrator's different equivalent circuits in the integrating and sampling phases. This model uses the OP-AMP input pair's tail current (I0) and overdrive voltage (von) as variables. The modulator's static and dynamic errors are analyzed. A group of optimized I0 and von for maximum SNR and power × area ratio can be obtained through this model. As examples, a MASH21 modulator for digital audio and a second order modulator for RFID baseband are implemented and tested, and they can achieve 91 dB and 72 dB respectively, which verifies the modeling and design criteria.

Binjie, Ge; Xin'an, Wang; Xing, Zhang; Xiaoxing, Feng; Qingqin, Wang

2010-09-01

438

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

439

Continental and oceanic crustal magnetization modelling  

NASA Technical Reports Server (NTRS)

Inversion of magnetic data from the MAGSAT satellite, to arrive at intensities of magnetization of the Earth's crust, was performed by two different methods. The first method uses a spherical harmonic model of the magnetic field. The coefficients believed to represent sources in the Earth's crust can then be inverted to arrive at vertical dipole moments per unit area at the Earth's surface. The spherical harmonic models contain coefficients of degrees of harmonics up to 23. The dipole moment per unit area for a surface element can then be determined by summing the contribution for each individual degree of harmonic. The magnetic moments were calculated for continental and oceanic areas separately as well as over certain latitudinal segments. Of primary concern was to determine whether there are any differences between continental and oceanic areas. The second analysis with magnetization intensities was made using narrower ranges of degrees of harmonics, assuming that higher degrees are present in the core field signal.

Harrison, C. G. A.; Hayling, K. L.

1984-01-01

440

Dynamics of ?-junction interferometer circuits  

Microsoft Academic Search

The ?-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and ?-type were studied as a model of high-Tc grain-boundary Josephson junction. The array dynamics and the critical current dependence on magnetic field are discussed. Experimental results for dc interferometers with 0 and ? high-Tc bi-crystal Josephson junctions

I. V. Borisenko; P. B. Mozhaev; G. A. Ovsyannikov; N. F. Pedersen

2002-01-01

441

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

442

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

443

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

444

Trading speed and accuracy by coding time: a coupled-circuit cortical model.  

PubMed

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. PMID:23592967

Standage, Dominic; You, Hongzhi; Wang, Da-Hui; Dorris, Michael C

2013-04-01

445

A new Model of Saturn's Magnetic Field  

Microsoft Academic Search

Using data from the Cassini spacecraft, we have created a new model of Saturn's magnetic field model that includes non-axisymmetric components. Previous solutions have not unambiguously resolved such components, instead being limited to (spin) axisymmetric components. We analyse the model using resolution analysis, error analysis and spectral analysis. We also examine Slepian basis functions in addition to the canonical spherical

M. G. Sterenborg; J. Bloxham

2008-01-01

446

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

447

2$\\\\,\\\\times\\\\,$ 25kV 50 Hz High-Speed Traction Power System: Short-Circuit Modeling  

Microsoft Academic Search

A2 25-kV 50 Hz traction power system was an- alyzed and modeled in the time domain in order to simulate short-circuit conditions and to attain a practical method to iden- tify the short circuit behavior of the traction system. In particular, due to the difficulty in assessing the track-line parameters which mainly depend on changing environmental conditions, the pos- sibility

Luigi Battistelli; Mario Pagano; Daniela Proto

2011-01-01

448

Multiloop model and simulation research of turbine generator with inter-turn short circuits fault of field windings  

Microsoft Academic Search

The inter-turn short circuits fault of field windings is one common fault in generators. It will cause serious damages if such faults are not handled properly in time?For this reason, according to the multi-loop method of AC machines this paper proposes multi-loop mathematical model of turbine generators with inter-turn short circuits fault of field windings. The inductance parameters are calculated

Ji-yong Hou; He-ming Li; Jun-qing Li; hong-yu Wang; Jing Fan

2009-01-01

449

Reduced-order modeling of large linear passive multi-terminal circuits using matrix-padé approximation  

Microsoft Academic Search

This paper introduces SyMPVL, an algorithm for the approximation of the symmetric multi-port transfer function of an RLC circuit. The algorithm employs a symmetric block-Lanczos algorithm to reduce the original circuit matrices to a pair of typically much smaller, banded, symmetric matrices. These matrices determine a matrix-Pade approximation of the multi-port transfer function, and can serve as a reduced-order model

Roland W. Freund; Peter Feldmann

1998-01-01

450

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)  

SciTech Connect

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 of GMR materials did not affect the operation nor the radiation hardness of Sandia's rad-hard CMOS technology, nor did the integration of GMR materials and exposure to ionizing radiation affect the magnetic properties of the GMR films. Thus, following deposition of GMR films on rad-hard integrated circuits, both the circuits and the films survived ionizing radiation levels consistent with DOE mission requirements. Furthermore, Sandia developed techniques to pattern deposited GMR films without degrading the completed integrated circuits upon which they were deposited. The present feasibility study demonstrated all the necessary processing elements to allow fabrication of the non-volatile memory elements onto an existing CMOS chip, and even allow the use of embedded (on-chip) non-volatile memories for system-on-a-chip applications, even in demanding radiation environments. However, funding agencies DTRA, AIM, and DARPA did not have any funds available to support the required follow-on technology development projects that would have been required to develop functioning prototype circuits, nor were such funds available from LDRD nor from other DOE program funds.

MYERS,DAVID R.; JESSING,JEFFREY R.; SPAHN,OLGA B.; SHANEYFELT,MARTY R.

2000-01-01

451

Vibration suppression of scale model of railway carbody with piezoelectric elements: a study focused on designing shunt circuits  

NASA Astrophysics Data System (ADS)

The goal of this study is to reduce the bending vibration of railway vehicles by applying a vibration suppression technique. The technique utilizes piezoelectric elements that are electrically shunted by an external circuit. This paper presents an investigation by using a scale model of a Shinkansen vehicle with a length of about 5m, mainly focused on implementation of shunt circuits. Small pieces of piezoelectric elements are bonded to its floor structure and electrically connected to a shunt circuit. The authors propose a new method to implement shunt circuits, a part of which is virtually realized. The circuits are designed for practical use under the condition of high voltage generated by the elements. Two types of shunt circuits are tested in this study. One is equivalent to an inductor and a resistor in series, and the other consists of a negative capacitor and a resistor. In actuality, the inductor and the negative capacitor are replaced by virtually realized impedance components. Results of excitation tests show that the circuits implemented based on the proposed method function as expected and bending vibration of the carbody can be reduced successfully.

Takigami, Tadao; Tomioka, Takahiro

2005-05-01

452

Modeling of the magnetic Barkhausen effect  

NASA Astrophysics Data System (ADS)

The magnetic Barkhausen effect has been found particularly useful for the nondestructive evaluation of ferromagnetic alloys. It has been shown to be sensitive to both the microstructure and the stress state of a material. In order to improve interpretation of the Barkhausen signals, models are needed which are able to directly relate the Barkhausen signals to material properties such as grain size. In this paper, the advantages and disadvantages of two existing magnetic Barkhausen models are studied with a view to their suitability for use in the field of nondestructive evaluation. The model of Alessandro, Beatrice, Bertotti, and Montorsi describes the pinning field which interacts with a domain wall in terms of a Wiener-Levy stochastic process. The domain wall velocity is then assumed to depend linearly on the difference between the local magnetic field and this pinning field. The assumptions of this model limit its use to experiments where the permeability and rate-of-change of applied field are constant. The model of Jiles, Sipahi, and Williams assumes that the Barkhausen activity in a given time interval is proportional to the rate-of-change of the magnetization which can be calculated from the hysteresis model of Jiles and Atherton. The model uses Poisson statistics to describe the stochastic nature of the Barkhausen events. A new model which incorporates ideas from both of these older models is introduced. The new model allows for changes in permeability with applied field and can accurately reproduce the frequency response of experimental Barkhausen signals. In order to validate the model, experiments were performed by measuring the magnetic flux produced when a sample was magnetized in a solenoid. The high-frequency components of the flux signal represent Barkhausen events and were separated from the main signal using a high-pass filter. This approach allowed quantitative comparisons to be made between the experiments and the model.-This work was supported by the NSF Industry/University Cooperative Research program. .

Clatterbuck, D. M.; Garcia, V. J.; Johnson, M. J.; Jiles, D. C.

2000-05-01

453

A Simple Model of Sedimentary Magnetization Acquisition  

NASA Astrophysics Data System (ADS)

Sedimentary magnetizations are fundamental to paleomagnetism, but the mechanisms that control remanence acquisition remain poorly constrained. Conceptually, acquisition of a sedimentary natural remanent magnetization (NRM) is simple; magnetic mineral particles that settle through a water column (or that have been deposited onto an unconsolidated sedimentary substrate) experience a geomagnetic torque that rotates them into alignment with the ambient field. Once the sediment is sufficiently compact, the magnetic particle orientations are locked-in, thereby preserving a record of the geomagnetic field at about the time of sediment deposition. Observed sedimentary NRMs, however, are often orders of magnitude smaller than the saturation remanent magnetization of the same sediment, which indicates a fundamentally inefficient remanence acquisition mechanism. We present results from a statistical model, based on the Fisher distribution, which considers magnetic particle reorientations toward an ambient field direction. The results of this simple model provide insights into a number of aspects of sedimentary magnetization acquisition. For example, an assemblage of randomly oriented magnetic particles can acquire a high-fidelity paleomagnetic signal with only small rotations (on the order of 1 degree) of the individual magnetic particles toward the ambient field direction. This demonstrates that the action of a geomagnetic torque does not need to be the dominant process involved in acquisition of sedimentary magnetizations, and that a weak directional bias on an assemblage of magnetic mineral particles could be responsible for the typically observed inefficiency of sedimentary remanence acquisition. Additionally, we show that an inherent inverse relationship exists between the relative paleointensity recorded by a sedimentary NRM and the uncertainty associated with the directional component of the NRM. This relationship has important implications for analysis of directional geomagnetic field behavior during periods with weak fields, such as paleomagnetic reversals and excursions.

Heslop, D.; Roberts, A. P.; Hawkins, R.

2013-12-01

454

Magnetic model for the ordered double perovskites  

NASA Astrophysics Data System (ADS)

We construct an effective spin model from the coupled spin-fermion problem appropriate to double perovskites of the form A2BB'O6 . The magnetic model that emerges is reminiscent of double exchange and we illustrate this “reduction” in detail for the case of perfect B-B' structural order, i.e., no antisite disorder. We estimate the effective exchange between the magnetic B ions in terms of the electronic parameters, study the “classical” magnetic model using Monte Carlo techniques and compare this approach to a full numerical solution of the spin-fermion problem. The agreement is surprisingly good and promises a quick estimate of magnetic properties when coupled with ab initio electronic structure. The scheme generalizes to the presence of antisite disorder.

Sanyal, Prabuddha; Majumdar, Pinaki

2009-08-01

455

A polycrystalline model for magnetic exchange bias  

NASA Astrophysics Data System (ADS)

This work introduces a realistic model for the magnetic behavior of polycrystalline ferromagnet/antiferromagnet (FM/AF) systems with granular interfaces. It considers that, for strong enough interface exchange coupling, the AF layer breaks the adjacent FM into small-sized domains and that at the interface there exist grains with uncompensated spins interacting with the FM magnetizations; the classification of these grains as unstable (rotatable, responsible for a coercivity enhancement) or stable (adding to the bias) depends on both the anisotropy and the magnetic coupling with the adjacent FM. The distinctive characteristic of the model is that the effective rotatable anisotropy changes when the external magnetic field is varied resulting in a non-zero hard-axis coercivity, a feature commonly observed, though little understood and often ignored. The applicability of this model was checked on a typical magnetron-sputtered IrMn/Co bilayer and excellent agreement between experiment and simulation was achieved.

Harres, A.; Geshev, J.

2012-08-01

456

A model of the magnetosheath magnetic field during magnetic clouds  

NASA Astrophysics Data System (ADS)

Magnetic clouds (MCs) are huge interplanetary structures which originate from the Sun and have a paramount importance in driving magnetospheric storms. Before reaching the magnetosphere, MCs interact with the Earth's bow shock. This may alter their structure and therefore modify their expected geoeffectivity. We develop a simple 3-D model of the magnetosheath adapted to MCs conditions. This model is the first to describe the interaction of MCs with the bow shock and their propagation inside the magnetosheath. We find that when the MC encounters the Earth centrally and with its axis perpendicular to the Sun-Earth line, the MC's magnetic structure remains mostly unchanged from the solar wind to the magnetosheath. In this case, the entire dayside magnetosheath is located downstream of a quasi-perpendicular bow shock. When the MC is encountered far from its centre, or when its axis has a large tilt towards the ecliptic plane, the MC's structure downstream of the bow shock differs significantly from that upstream. Moreover, the MC's structure also differs from one region of the magnetosheath to another and these differences vary with time and space as the MC passes by. In these cases, the bow shock configuration is mainly quasi-parallel. Strong magnetic field asymmetries arise in the magnetosheath; the sign of the magnetic field north-south component may change from the solar wind to some parts of the magnetosheath. We stress the importance of the Bx component. We estimate the regions where the magnetosheath and magnetospheric magnetic fields are anti-parallel at the magnetopause (i.e. favourable to reconnection). We find that the location of anti-parallel fields varies with time as the MCs move past Earth's environment, and that they may be situated near the subsolar region even for an initially northward magnetic field upstream of the bow shock. Our results point out the major role played by the bow shock configuration in modifying or keeping the structure of the MCs unchanged. Note that this model is not restricted to MCs, it can be used to describe the magnetosheath magnetic field under an arbitrary slowly varying interplanetary magnetic field.

Turc, L.; Fontaine, D.; Savoini, P.; Kilpua, E. K. J.

2014-02-01

457

Circuit coupled simulation of a claw-pole alternator by a temporary linearization of the 3D-FE model  

Microsoft Academic Search

During the final stage in the design of electrical machines adequate models are required to predict the behavior at given points of operation. Due to its irreducible 3D flux path structure and the connected bridge rectifier, the claw pole generator is a challenging field-circuit coupled system. It can be solved either by permeance models, state space models or numerically strong

E. Lange; M. van der Giet; F. Henrotte; K. Hameyer

2008-01-01

458

An Integrated Amorphous Silicon Gate Driver Circuit Using Voltage-Controlled Capacitance Modeling for High Definition Television  

NASA Astrophysics Data System (ADS)

We have developed the integrated amorphous silicon gate driver circuit using the model extraction technique of the inverted staggered and nonsymmetric amorphous silicon (a-Si) thin film transistor. The relation between capacitance characteristics of hydrogenated a-Si (a-Si:H) integrated transistors and the output signal of the gate driver circuit is analyzed using UTMOST IV ver. 1.6.4.R and SMARTSPICE ver. 3.19.15.C. The accuracy of the simulated gate output signal using voltage-controlled capacitance modeling is verified with measured data. The a-Si gate driver circuit using the proposed (TFT) model increased the accuracy of rising (95.3%) and falling (92%) time, compared to the conventional model. The suggested model extraction technique can be used for bottom gate and asymmetric TFT structures.

Han, Sang-Kug; Choi, Hoon; Moon, Kyo-Ho; Choi, Young-Seok; Jeong, Kyung-Deuk; Park, Kwang-Mook; Choi, Sie-Young

2012-04-01

459

A simple analysis of inductively coupled discharge using transformer circuit model  

NASA Astrophysics Data System (ADS)

Correlations between plasma parameters in an inductively coupled discharge were studied by an air-cored transformer model. By applying the transformer circuit model which is well-established by previous workers [1], for the maximum power transfer the optimal condition between external parameters (chamber dimension L, driving frequency ?) and internal parameters (skin depth ?, electron-neutral collision frequency ?en) was obtained. From this work, it was found that a maximum power transfer condition correspond to ? L when ?en / ? << 1, while ?/ L (2? / ?en)^1/2 when ?en / ? >> 1. This result of circuit analysis is consistent to the state of H to E mode transition which is existing results based on calculation of Maxwell's equation [2]. Our experimental results, as well as other researchers' results are also compared and agreed well with the theoretical value. This study will offers another view point of analyzing characteristics of inductively coupled plasma, and the theoretical predictions will play a very useful role in the system design or improving process efficiency. [4pt] [1] Piejak R B, Godyak V A and Alexandrovich B M, Plasma Sources Sci. Technol. 1 179 (1992) [0pt] [2] Lee and Chung, Physics. Plasmas, 13 063510 (2006).

Kim, Yound-Do; Lee, Hyo-Chang; Chung, Chin-Wook

2011-11-01

460

Modifications and Modelling of the Fission Surface Power Primary Test Circuit (FSP-PTC)  

NASA Technical Reports Server (NTRS)

An actively pumped alkali metal flow circuit, designed and fabricated at the NASA Marshall Space Flight Center, underwent a range of tests at MSFC in early 2007. During this period, system transient responses and the performance of the liquid metal pump were evaluated. In May of 2007, the circuit was drained and cleaned to prepare for multiple modifications: the addition of larger upper and lower reservoirs, the installation of an annular linear induction pump (ALIP), and the inclusion of the Single Flow Cell Test Apparatus (SFCTA) in the test section. Performance of the ALIP, provided by Idaho National Laboratory (INL), will be evaluated when testing resumes. The SFCTA, which will be tested simultaneously, will provide data on alkali metal flow behavior through the simulated core channels and assist in the development of a second generation thermal simulator. Additionally, data from the first round of testing has been used to refine the working system model, developed using the Generalized Fluid System Simulation Program (GFSSP). This paper covers the modifications of the FSP-PTC and the updated GFSSP system model.

Garber, Ann E.

2008-01-01

461

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

462

Model of Protein Kinase B for Cell Survival/Death and its Equivalent Bio Circuit  

NASA Astrophysics Data System (ADS)

Signaling pathways have traditionally focused on delineating immediate upstream and down stream interactions, and then organizing these interactions into linear cascades that relay and regulate information from cell surface receptors to cellular effectors such as metabolic enzymes, channels or transcription factors. However, recent analyses of signaling pathways have revealed that cellular signals do not necessarily propagate in a linear fashion. Because of their size and complexity, these networks are often too complicated for the human mind to organize and analyze. AkT (protein kinase B) is a central signaling molecule in the phosphatidylinositol 3-kinase pathway that is frequently activated in human cancer. Here we provide an overview of recent findings, how AkT promotes cell survival by inhibiting apoptosis by phosphorylating and inactivating several targets, including forkhead transcription factors, and caspase-9. The ability of AkT to promote survival was dependent on and proportional to its kinase activity. We have made computational model for AkT, on the basis of that model we have made the truth tables, Boolean equations and than implement the equations using logic circuits and Bio-circuits showing cell survival and death.

Jain, Shruti; Naik, Pradeep K.; Bhooshan, Sunil V.

2011-12-01

463

Transcranial magnetic stimulation in different current directions activates separate cortical circuits.  

PubMed

Transcranial magnetic stimulation (TMS) to the primary motor cortex (M1) produces a series of corticospinal descending waves, with a direct (D) wave followed by several indirect (I) waves. TMS inducing posterior-anterior (PA) current in the brain predominantly recruits the early I1-wave, whereas anterior-posterior (AP) directed current preferentially recruits the late I3-wave. However, it is not known whether I-waves elicited by different current directions are mediated by the same neuronal populations. We studied the neuronal mechanisms mediating I-waves by examining the influence of short-latency afferent inhibition (SAI) on various I-waves. SAI was tested with electrical median nerve stimulation at the wrist followed by TMS to the contralateral M1 at different current directions. Surface electromyograms and single motor units were recorded from the first dorsal interosseous muscle. SAI was weaker for the AP compared with that for the PA current direction. With increasing median nerve stimulation intensities, SAI increased for the PA direction but showed a U-shaped relationship for the AP direction. SAI produced more inhibition of late I-waves generated by PA than those generated by AP current direction. We conclude that late I-waves generated by PA and AP current directions are mediated by different neuronal mechanisms. PMID:21148098

Ni, Zhen; Charab, Samer; Gunraj, Carolyn; Nelson, Aimee J; Udupa, Kaviraja; Yeh, I-Jin; Chen, Robert

2011-02-01

464

Theta-burst repetitive transcranial magnetic stimulation suppresses specific excitatory circuits in the human motor cortex  

PubMed Central

In four conscious patients who had electrodes implanted in the cervical epidural space for the control of pain, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation (TMS) over the motor cortex before and after a 20 s period of continuous theta-burst stimulation (cTBS). It has previously been reported that this form of repetitive TMS reduces the amplitude of motor-evoked potentials (MEPs), with the maximum effect occurring at 5–10 min after the end of stimulation. The present results show that cTBS preferentially decreases the amplitude of the corticospinal I1 wave, with approximately the same time course. This is consistent with a cortical origin of the effect on the MEP. However, other protocols that lead to MEP suppression, such as short-interval intracortical inhibition, are characterized by reduced excitability of late I waves (particularly I3), suggesting that cTBS suppresses MEPs through different mechanisms, such as long-term depression in excitatory synaptic connections.

Di Lazzaro, V; Pilato, F; Saturno, E; Oliviero, A; Dileone, M; Mazzone, P; Insola, A; Tonali, PA; Ranieri, F; Huang, YZ; Rothwell, JC

2005-01-01

465

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

466

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

467

Hybrid Circuit Simulator Including a Model for Single Electron Tunneling Devices  

Microsoft Academic Search

A hybrid circuit simulator has been developed thatincorporates elements of single electron devicesinto the conventional circuit simulator SPICE(Simulation Program with Integrated Circuit Emphasis).The elements can consist of an arbitrary networkof tunnel junctions and capacitors,whose characteristics are calculatedusing a master equation method.By employing the hybrid circuit simulator,we studied a turnstile devicefeeding the inputof a complementary metal-oxide-semiconductor (CMOS) inverter,and were able to

Masaharu Kirihara; Kazuo Nakazato; Mathias Wagner

1999-01-01

468

Multi-objective genetic approach for analog circuit sizing using SVM macro-model  

Microsoft Academic Search

Analog circuit sizing is the task to determine the sizes of all components in the circuit during automated synthesis. Randomized combinatorial optimization algorithms are desired for quicker determination of a set of optimal sizes of the components. These algorithms require set of multiple performance parameters, for a very large number of sized circuits. Therefore the reduction in time required to

D. Boolchandani; Anupam Kumar; Vineet Sahula

2009-01-01

469

Experimental results and modeling techniques for substrate noise in mixed-signal integrated circuits  

Microsoft Academic Search

An experimental technique is described for observing the effects of switching transients in digital MOS circuits that perturb analog circuits integrated on the same die by means of coupling through the substrate. Various approaches to reducing substrate crosstalk (the use of physical separation of analog and digital circuits, guard rings, and a low-inductance substrate bias) are evaluated experimentally for a

David K. Su; Marc J. Loinaz; Shoichi Masui; Bruce A. Wooley

1993-01-01

470