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1

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

2

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

3

This paper presents a simplified lumped-parameter magnetic circuit model (MCM) of a fractional-slot concentrated-winding (FSCW) interior permanent magnet (IPM) machine that provides rapid estimates of machine performance for use in machine design optimization software. This model incorporates several key nonlinear phenomena including (i) magnetic saturation; (ii) cross-saturation effects between the d- and q-axes affecting both flux linkages and inductances; (iii)

Jagadeesh K. Tangudu; Thomas M. Jahns; Ayman EL-Refaie; Z. Q. Zhu

2009-01-01

4

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

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

F. Piriou; A. Razek

1990-01-01

5

A coupling between electric circuits and 2D magnetic field modeling

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

6

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

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

7

Reduced-Order Modeling of High-Fidelity Magnetic Equivalent Circuits

Magnetic components, such as inductors and transformers, enable short-term energy storage and transfer and are essential for many power electronic converters. Physics-based models of magnetic systems, such as finite element-based models and\\/or high-fidelity magnetic equivalent circuit (HFMEC) models, accurately represent the magnetic device. However, these models are computationally intensive and hard to formulate. In this paper, an HFMEC approach for

Ali Davoudi; Patrick L. Chapman; Juri Jatskevich; Alireza Khaligh

2009-01-01

8

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

9

NSDL National Science Digital Library

Students use the same method as in the activity from lesson 2 of this unit 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,

10

NASA Astrophysics Data System (ADS)

The computer-aided modeling of permanent magnet (PM) synchronous generators with multiple damping circuits feeding electronically switched loads is considered. The continuous switching in the power electronics associated with such generator systems results in a continuous change in the machine system topologies. Accordingly, the modeling of such systems is done on an instantaneous basis in the abc frame of reference. The key parameters needed for this modeling approach, including the induced back emfs and the various winding inductances, are determined from a series of comprehensive finite-element nonlinear magnetic field solutions. Therefore, effects of magnetic saturation and inherent harmonics in the flux linkages on the machine parameters are accounted for. The method is applied to a two-pole, 75-kVA, 208-V, 24,000-r/min (400-Hz) PM synchronous generator with multiple rotor damping circuits. The computed inductance and emf data are compared to measured data, and the results are found to agree well.

Arkadan, Abd A.

11

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

12

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

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 Alq{sub 3} 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., E-mail: dmgleite@fc.unesp.br [UNIFEI—Universidade Federal de Itajubá, Av. BPS, 1303, 37500-903 Itajubá, MG (Brazil); Batagin-Neto, A.; Nunes-Neto, O. [UNESP—Univ Estadual Paulista, POSMAT—Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, 17033-360 Bauru, SP (Brazil); Gómez, J. A. [Departamento de Física, FFCLRP-USP, Av. Bandeirantes 3900, 14040-901 Ribeirão Preto, SP (Brazil); Graeff, C. F. O. [UNESP—Univ Estadual Paulista, POSMAT—Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, 17033-360 Bauru, SP (Brazil); DF-FC, UNESP—Univ Estadual Paulista, Av. Eng. Luiz Edmundo Carrijo Coube, 14-01, 17033-360 Bauru, SP (Brazil)

2014-01-21

13

Magnetic compression laser driving circuit

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

14

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

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

15

NSDL National Science Digital Library

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

Christian, Wolfgang

2009-10-05

16

Modelling cement grinding circuits

Modelling and simulation studies were carried out at 26 cement clinker grinding circuits including tube mills, air separators and high pressure grinding rolls in 8 plants. The results reported earlier have shown that tube mills can be modelled as several mills in series, and the internal partition in tube mills can be modelled as a screen which must retain coarse

H. Benzer; L. Ergun; A. J. Lynch; M. Oner; A. Gunlu; I. B. Celik; N. Aydogan

2001-01-01

17

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

18

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

19

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

20

Designing HTS coils for magnetic circuits

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

21

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

22

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

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

23

The neocortex is perhaps the highest region of the human brain, where audio and visual perception takes place along with many important cognitive functions. An important research goal is to describe the mechanisms implemented by the neocortex. There is an apparent regularity in the structure of the neocortex [Brodmann 1909, Mountcastle 1957] which may help simplify this task. The work reported here addresses the problem of how to describe the putative repeated units ('cortical circuits') in a manner that is easily understood and manipulated, with the long-term goal of developing a mathematical and algorithmic description of their function. The approach is to reduce each algorithm to an enhanced perceptron-like structure and describe its computation using difference equations. We organize this algorithmic processing into larger structures based on physiological observations, and implement key modeling concepts in software which runs on parallel computing hardware.

Rohrer, Brandon Robinson; Rothganger, Fredrick H.; Verzi, Stephen J.; Xavier, Patrick Gordon

2010-09-01

24

A Bistable Vibration Energy Harvester with Closed Magnetic Circuit

NASA Astrophysics Data System (ADS)

In this work, to increase magnetic flux passing through the electric coil in a bistable vibration energy harvester, the magnetic circuit is made closed by introducing two coil systems which have magnetic core in their axis holes. The magnetic resistance of the magnetic circuit, composed of silicon steel and thin air gaps, is supressed to be small. The double well potential is realized from the spring force and nonlinear magnetic force between the magnets and the magnetic core. Two harvesters with opened and closed magnetic circuits are manufactured for comparison. It is also shown that the closed magnetic circuit can effectively improve the output power.

Sato, Takahiro; Sugisawa, Takeshi; Igarashi, Hajime

2014-11-01

25

Magnetic Circuit Analysis of a Tubular Permanent Magnet Linear Alternator

A simplified magnetic circuit analysis of a tubular permanent magnet linear alternator (PMLA) is presented. The analysis accounts for saturation, leakage and armature reaction. Under these conditions the fields in every portion of the linear alternator (LA) are determined. The field determination leads to the alternator induced voltage and inductances.

S. A. NASAR; C. CHEN

1987-01-01

26

Electric Magnetic Circuit Active Elements Based on Magnetorheological Elastomers

The circuit magnetic active element presented in the paper is based on electroconductive magnetorheological elastomer. This element and the experimental set-up for studies in magnetic field are presented in some detail. It is shown that the voltage U at the outlet of the electric circuit depends on the intensity H of the magnetic field and is considerably influenced by the

G. Catana; B. Vatzulik; O. E. Andrei; L. Chirigiu; I. Bica

2010-01-01

27

Biasing and fast degaussing circuit for magnetic materials

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

28

Biasing and fast degaussing circuit for magnetic materials

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

29

Reconfigurable Circuits Using Magnetic Tunneling Junction Memories

NASA Astrophysics Data System (ADS)

This paper presents the first results of our work to research and develop new reconfigurable circuits and topologies based on Magnetic RAM (MRAM) memory elements. This work proposes a coarse-grained reconfigurable array using MRAM. A coarse-grained array, where each reconfigurable element computes on 4-bit or larger input words, is more suitable to execute data-oriented algorithms and is more able to exploit large amounts of operation-level parallelism than common fine-grained architectures. The architecture is organized as a one-dimensional array of programmable ALU and the configuration bits are stored in MRAM. MRAM provide non-volatility with cell areas and with access speeds comparable to those of SRAM and with lower process complexity than FLASH memory. MRAM can also be efficiently organized as multi-context memories.

Silva, Victor; Fernandes, Jorge; Neto, Horácio

30

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

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

31

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

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

32

Integrated circuit model development for EMP

The response of Integrated Circuits (IC) to pulsed and gated sine-wave stimuli was used to develop reasonably accurate device models for EMP assessment. These IC models were then used in conjunction with circuit and transfer function models to determine the failure threshold (upset and burnout) to postulated EMP disturbance. This paper describes the model development and test verification of IC

C. Kleiner; J. Nelson; F. Vassallo; E. Heaton

1974-01-01

33

Equivalent Circuit Modeling of Hysteresis Motors

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

34

SPICE Modeling for Small Geometry MOSFET Circuits

VLSI circuit simulation requires computationally efficient MOSFET models. In this paper, VLSI circuit simulator models for the active device and some important passive devices are described. A quasi-physical short channel MOSFET current model is derived. This current model contains both above-threshold and subthreshold components. The values of the model parameter are extracted automatically from measured I-V data. The reduction in

Ping Yang; Pallab K. Chatterjee

1982-01-01

35

Sequential Circuit Verification Using Symbolic Model Checking

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

36

Symbolic model checking for sequential circuit verification

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

37

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

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

38

Low-Order Dynamic Magnetic Equivalent Circuits of Saturated Steel Laminations

Physics-based modeling of laminated magnetic devices accurately represents underlying dynamic characteristics. However, these models are hard to formulate, oversimplified with crude approximations, and computationally intensive. In this paper, a high-fidelity magnetic equivalent circuit of steel lamination is set forth based on geometrical and material data. The nonlinearity imposed by saturation is also considered. Automated linear and nonlinear order-reduction techniques are

A. Davoudi; A. Khaligh; M. Amrhein; P. L. Chapman; J. Jatskevich

2007-01-01

39

Resistive companion battery modeling for electric circuit simulations , R. Dougalb

Resistive companion battery modeling for electric circuit simulations B. Wua , R. Dougalb , R for electric circuit simulations. With a RC numerical solver, simulations of complex electric systems can reserved. Keywords: Battery modeling; Battery simulation; Electric circuit simulation; Resistive companion

40

Quantum Computation Beyond the "Standard Circuit Model"

Construction of explicit quantum circuits follows the notion of the "standard circuit model" introduced in the solid and profound analysis of elementary gates providing quantum computation. Nevertheless the model is not always optimal (e.g. concerning the number of computational steps) and it neglects physical systems which cannot follow the "standard circuit model" analysis. We propose a computational scheme which overcomes the notion of the transposition from classical circuits providing a computation scheme with the least possible number of Hamiltonians in order to minimize the physical resources needed to perform quantum computation and to succeed a minimization of the computational procedure (minimizing the number of computational steps needed to perform an arbitrary unitary transformation). It is a general scheme of construction, independent of the specific system used for the implementation of the quantum computer. The open problem of controllability in Lie groups is directly related and rises to prominence in an effort to perform universal quantum computation.

K. Ch. Chatzisavvas; C. Daskaloyannis; C. P. Panos

2006-08-16

41

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

Dong Lai

2012-06-17

42

Development of a new magnetic circuit for slim microspeakers

NASA Astrophysics Data System (ADS)

In the minimultimedia market, functional diversity, high performance, and design are given top priority. Lightweight mobile phones of unique design especially attract customer interest and are usually considered to be highly competitive items in the marketplace. Therefore, mobile phones need wider and thinner liquid crystal displays and smaller microspeakers with high acoustic performance. There are two main directions for development of slim microspeakers. One is reducing the thickness, and the other is reducing the width. In the case of reducing the width, the total magnet volume is maintained through extending the length of the magnet circuit [S. M. Hwang et al., IEEE Trans. Magn. 39, 2003 (2003)]. In contrast, reducing the thickness results in a reduction in total magnet volume unless width is increased, which causes many difficulties in the manufacturing process. In this paper, we introduce a new magnetic circuit for slim microspeakers. This new magnetic circuit, which excludes the top plate, makes it possible to manufacture slimmer microspeakers more cost-effectively without any loss of acoustic performance.

Lee, Chang-Min; Kwon, Joong-Hak; Hwang, Gun-Yong; Hwang, Sang-Moon

2009-04-01

43

Globally Clocked Magnetic Logic Circuits Michael Hall

with the Stoner-Wohlfarth switching astroids for the spin valves. The possi- ble magnetic field vectors that can leaves the net field in the left half of the astroid. A high current (D=1) makes the net field positive that each alone will not result in a field outside of the stable region in the astroid. With enable low

Chamberlain, Roger

44

Modeling neural circuits in Parkinson's disease.

Parkinson's disease (PD) is caused by abnormal neural activity of the basal ganglia which are connected to the cerebral cortex in the brain surface through complex neural circuits. For a better understanding of the pathophysiological mechanisms of PD, it is important to identify the underlying PD neural circuits, and to pinpoint the precise nature of the crucial aberrations in these circuits. In this paper, the general architecture of a hybrid Multilayer Perceptron (MLP) network for modeling the neural circuits in PD is presented. The main idea of the proposed approach is to divide the parkinsonian neural circuitry system into three discrete subsystems: the external stimuli subsystem, the life-threatening events subsystem, and the basal ganglia subsystem. The proposed model, which includes the key roles of brain neural circuit in PD, is based on both feed-back and feed-forward neural networks. Specifically, a three-layer MLP neural network with feedback in the second layer was designed. The feedback in the second layer of this model simulates the dopamine modulatory effect of compacta on striatum. PMID:25416983

Psiha, Maria; Vlamos, Panayiotis

2015-01-01

45

? Abstract— Aiming the application of localized hyperthermia, a magnetic induction system with new approaches is proposed. The techniques in this system for improving the effectiveness of localized hyperthermia are that using magnetic circuit and the multiple-coil array instead of a giant coil for generating magnetic field. Specially, amorphous metal is adopted as the material of magnetic circuit. Detail design

Chi-Fang Huang; Xi-Zhang Lin; Yi-Ru Yang

2009-01-01

46

NASA Astrophysics Data System (ADS)

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

Lai, Dong

2012-09-01

47

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

48

Circuit Theory for Analysis and Design of Spintronic Integrated Circuits

We present a theoretical and a numerical formalism for analysis and design of spintronic integrated circuits (SPINICs). The proposed formalism encompasses a generalized circuit theory for spintronic integrated circuits based on nanomagnetic dynamics and spin transport. We derive the circuit models for vector spin conduction in non-magnetic and magnetic components. We then propose an extension to the modified nodal analysis for the analysis of spin circuits. We demonstrate the applicability of the proposed theory using an example spin logic circuit.

Manipatruni, Sasikanth; Young, Ian A

2011-01-01

49

Modeling digital circuits for troubleshooting - An overview

NASA Astrophysics Data System (ADS)

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

Hamscher, Walter

50

NASA Astrophysics Data System (ADS)

Metamaterial thermal emitters and absorbers have been widely studied for different geometric patterns by exciting a variety of electromagnetic resonances. A resistor-inductor-capacitor (RLC) circuit model is developed to describe the magnetic resonances (i.e. magnetic polaritons) inside the structures. The RLC circuit model allows the prediction of not only the resonance frequency, but also the full width at half maximum and quality factor for various geometric patterns. The parameters predicted by the RLC model are compared with the finite-difference time-domain simulation. The magnetic field distribution and the power dissipation density profile are also used to justify the RLC circuit model. The geometric effects on the resonance characteristics are elucidated in the wire (or strip), cross, and square patterned metamaterial in the infrared region. This study will facilitate the design of metamaterial absorbers and emitters based on magnetic polaritons.

Sakurai, Atsushi; Zhao, Bo; Zhang, Zhuomin M.

2014-12-01

51

A NOVEL MODELING TECHNIQUE TO SOLVE A CLASS OF RECTANGULAR WAVEGUIDE BASED CIRCUITS AND RADIATORS

A new methodology has been developed, based on moment method; for analyzing a class of rectangular waveguide based circuits and radiators. The methodology involves in modeling the given structure using tetragonal bricks or cavities and then replacing all the apertures and discontinuities with equivalent magnetic current densities so that the given structure can be analyzed using only the Magnetic Field

A. Chakrabarty

2006-01-01

52

Research of the turbogenerator stability using field-circuit modeling

This paper presents two-dimensional field-circuit model of 500 MVA turbogenerator. Model is designed to calculate static and dynamic characteristics of machine. During solving field equations real physical characteristics of materials, configuration of windings, damper circuit and motion elements in electromagnetic field are taken into account. In circuit part there is an electrical scheme. The electrical elements correspond with winding in

P. Kisielewski; L. Antal

2010-01-01

53

Probabilistic Graphical Models for the Diagnosis of Analog Electrical Circuits

Probabilistic Graphical Models for the Diagnosis of Analog Electrical Circuits Christian Borgelt electrical circuit. This model can be used to do probabilis- tic diagnosis based on manufacturer supplied approaches to the diagnosis of electrical circuits have been developed [10, 11]. Examples are: the fault

Borgelt, Christian

54

Probabilistic Graphical Models for the Diagnosis of Analog Electrical Circuits

Probabilistic Graphical Models for the Diagnosis of Analog Electrical Circuits Christian Borgelt electrical circuit. This model can be used to do probabilisÂ tic diagnosis based on manufacturer supplied approaches to the diagnosis of electrical circuits have been developed [10, 11]. Examples are: the fault

Borgelt, Christian

55

Behavioural EMI Models of Complex Digital VLSI Circuits Thomas Steinecke

Behavioural EMI Models of Complex Digital VLSI Circuits Thomas Steinecke Infineon Technologies AG-Meyer-Allee 25, 13355 Berlin Germany 1. ABSTRACT Increasing EMI potential of high-performance digital circuits-based EMI simulations. A promising modelling approach for digital VLSI circuits is presented and a silicon

Paris-Sud XI, UniversitÃ© de

56

High-Sensitivity Actuator with New Magnetic Circuit in Optical Pickup

A lens actuator is an important mechanical-electrical component in optical pickup. For the high-sensitivity actuator used in a super-multi recorder, a novel magnetic circuit is proposed in this paper. This magnetic circuit consists of six thick permanent magnets with regulated placement, two thin permanent magnets, a base yoke, and an upper yoke. Experimental results verified the feasibility of the designed

Buqing Zhang; Jianshe Ma; Longfa Pan; Xuemin Cheng; Hua Hu; Yi Tang

2008-01-01

57

Conceptualizing Series and Parallel Circuits Through 3-D Modeling

Understanding series and parallel circuits involves conceptualizing how voltages drop and currents pass through an entire circuit. A technique that I found useful in helping students conceptualize and remember the nature of voltage drops in circuits involves sculpting 3-D wire models.

Tony Minich

2005-01-01

58

Equivalent circuit models for ac impedance data analysis

NASA Technical Reports Server (NTRS)

A least-squares fitting routine has been developed for the analysis of ac impedance data. It has been determined that the checking of the derived equations for a particular circuit with a commercially available electronics circuit program is essential. As a result of the investigation described, three equivalent circuit models were selected for use in the analysis of ac impedance data.

Danford, M. D.

1990-01-01

59

Dual random circuit breaker network model with equivalent thermal circuit network

NASA Astrophysics Data System (ADS)

A SPICE-based dual random circuit breaker (RCB) network model with an equivalent thermal circuit network has been proposed in order to emulate resistance switching (RS) of unipolar resistive random access memory (RRAM). The dual RCB network model consists of the electrical RCB network model for the forming and set operations and the equivalent thermal circuit network model for the reset operation. In addition, the proposed model can explain the effects of heat dissipation on the memory and threshold RS with the variation in electrode thickness.

Kim, Kwanyong; Yoon, Seong Jun; Choi, Woo Young

2014-02-01

60

Computation of magnetic suspension of maglev systems using dynamic circuit theory

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

61

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

62

Model Reduction for a Class of Nonlinear Electrical Circuits

Model Reduction for a Class of Nonlinear Electrical Circuits by Reduction of Linear Subcircuits: electrical circuits, passive systems, model reduction, modified nodal analysis 1. Introduction Model for key technologies" http://www.matheon.de #12;Model Reduction for a Class of Nonlinear Electrical

Reis, Timo

63

Linear circuit models for on-chip quantum electrodynamics

We present equivalent circuits that model the interaction of microwave resonators and quantum systems. The circuit models are derived from a general interaction Hamiltonian. Quantitative agreement between the simulated resonator transmission frequency, qubit Lamb shift and experimental data will be shown. We demonstrate that simple circuit models, using only linear passive elements, can be very useful in understanding systems where a small quantum system is coupled to a classical microwave apparatus.

Alpár Mátyás; Christian Jirauschek; Federico Peretti; Paolo Lugli; György Csaba

2011-06-17

64

1358 IEEE TRANSACTIONS ON MAGNETICS, VOL. 40, NO. 2, MARCH 2004 Eddy-Current Effects in Circuit Abstract--This paper deals with the modeling of eddy currents generated by arc motion during opening phases in determining eddy currents in splitter plates, the second one is devoted to the calculation of eddy currents

Paris-Sud XI, UniversitÃ© de

65

The model-based analysis of a switched reluctance machine, which has significant losses in the iron core, requires the machine to be represented by parameters that account for nonlinearities caused by both the magnetic saturation and the iron losses. This paper describes the methodology for determining the parameters of the equivalent electric circuit that includes the representation of iron losses. The

Jasmin Corda; Shabbir M. Jamil

2010-01-01

66

Respiratory circuits: development, function and models.

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

Mellen, Nicholas M; Thoby-Brisson, Muriel

2012-08-01

67

Modeling of cerebral aneurysm using equivalent electrical circuit (Lumped Model).

The circle of Willis (CoW) is a key asset in brain performance as it supports adequate blood supply to the brain. The lumped method (electrical equivalent circuits) is a useful model to simulate the process of the human cardiovascular system. In this study, the whole cardiovascular system is modeled, using an equivalent electrical circuit to investigate an aneurysm in an artery. The cerebrovascular system consists of 29 compartments, which includes the CoW. Each vessel is modeled by a resistor, a capacitor and an inductor. Using MATLAB Simulink, the left and right ventricles are modeled by controlled voltage sources and diodes. The effects of the left internal carotid artery aneurysm (Fusiform) on the pressure of the efferent arteries in the circle of Willis are studied. The modeling results are entirely in agreement with the available clinical observations. The results of the present study may have clinical implications for modeling different cardiovascular diseases, such as arterial stiffness and atherosclerosis. PMID:23887086

Abdi, M; Karimi, A; Navidbakhsh, M; Hassani, K; Faghihi, S

2014-03-01

68

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

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

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

2008-06-25

69

Short-circuit current model of organic solar cells

NASA Astrophysics Data System (ADS)

A physical model is presented for short-circuit current of organic solar cells based on the flow of both majority and minority carriers. According to the proposed model, the temperature, free carrier generation rate, light intensity, donor and acceptor dopant concentration dependences of short-circuit current can be well described. Good agreement between the calculated results and experimental data is found.

Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Ming

2014-10-01

70

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

71

Magnetic Circuit Design for Six-Wire Suspension Type Actuator in a Super Multioptical Pickup

We have developed a new magnetic circuit consisting of eight permanent magnets with special placement order. Here, we analyze the magnetic flux density distribution, the driving force distribution, and the interference force using the finite-element method. The driving sensitivity of the actuator at low frequency is nearly twice that of a conventional actuator. We have built several samples and compared

Buqing Zhang; Jianshe Ma; Longfa Pan; Xuemin Cheng; Hua Hu; Yi Tang

2008-01-01

72

SET/RESET PULSE CIRCUITS FOR MAGNETIC SENSORS AN-201 Honeywell's line of magnetoresistive permalloy sensors are sensitive to magnetic fields less than 100 Âµgauss in a Â±2 gauss range. In order to achieve, or flip, the polarity of film magnetization, thus changing the sensor characteristics. Following

Kleinfeld, David

73

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

74

Generalized Volterra Series model for highly nonlinear optical interconnects, circuits and devices

series approach for nonlinear dynamic systems modeling,” IEEE Transactions on CircuitsSeries Model for Highly Nonlinear Optical Interconnects, CircuitsSeries model for highly nonlinear optical interconnects, circuits

Yücetürk, Emel

2007-01-01

75

A SPICE BEHAVIORAL MODEL FOR CURRENT-CONTROLLED MAGNETIC INDUCTORS

A SPICE BEHAVIORAL MODEL FOR CURRENT-CONTROLLED MAGNETIC INDUCTORS Evgeny Rozanov and Sam Ben@ee.bgu.ac.il Website: www.ee.bgu.ac.il/~pel ABSTRACT A new SPICE-compatible behavioral model for magnetic controlled the simulation and experimental results. 1. INTRODUCTION SPICE simulation of electronic circuits that include

76

Parameterized modeling of multiport passive circuit blocks

System level design optimization has recently started drawing the attention of circuit designers. A system level optimizer would search over the entire design space, adjusting the parameters of interest, for optimal ...

Mahmood, Zohaib

2010-01-01

77

Verification of the predictive capabilities of the 4C code cryogenic circuit model

NASA Astrophysics Data System (ADS)

The 4C code was developed to model thermal-hydraulics in superconducting magnet systems and related cryogenic circuits. It consists of three coupled modules: a quasi-3D thermal-hydraulic model of the winding; a quasi-3D model of heat conduction in the magnet structures; an object-oriented a-causal model of the cryogenic circuit. In the last couple of years the code and its different modules have undergone a series of validation exercises against experimental data, including also data coming from the supercritical He loop HELIOS at CEA Grenoble. However, all this analysis work was done each time after the experiments had been performed. In this paper a first demonstration is given of the predictive capabilities of the 4C code cryogenic circuit module. To do that, a set of ad-hoc experimental scenarios have been designed, including different heating and control strategies. Simulations with the cryogenic circuit module of 4C have then been performed before the experiment. The comparison presented here between the code predictions and the results of the HELIOS measurements gives the first proof of the excellent predictive capability of the 4C code cryogenic circuit module.

Zanino, R.; Bonifetto, R.; Hoa, C.; Richard, L. Savoldi

2014-01-01

78

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

79

Transformation of quantum photonic circuit models by term rewriting

The development of practical methods for synthesis and verification of complex photonic circuits presents a grand challenge for the nascent field of quantum engineering. Of course, classical electrical engineering provides essential foundations and serves to illustrate the degree of sophistication that can be achieved in automated circuit design. In this paper we explore the utility of term rewriting approaches to the transformation of quantum circuit models, specifically applying rewrite rules for both reduction/verification and robustness analysis of photonic circuits for autonomous quantum error correction. We outline a workflow for quantum photonic circuit analysis that leverages the Modelica framework for multi-domain physical modeling, which parallels a previously described approach based on VHSIC Hardware Description Language (VHDL).

Gopal Sarma; Ryan Hamerly; Nikolas Tezak; Dmitri S. Pavlichin; Hideo Mabuchi

2012-06-06

80

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

81

Quantum Magnetism Analysis Model

NSDL National Science Digital Library

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

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

2012-07-27

82

Note on homological modeling of the electric circuits

Based on a simple example, it is explained how the homological analysis may be applied for modeling of the electric circuits. The homological branch, mesh and nodal analyses are presented. Geometrical interpretations are given.

Eugen Paal; Märt Umbleja

2014-06-23

83

Modeling of three dimensional defects in integrated circuits

Although the majority of defects found in manufacturing lines of Integrated Circuits [ IC's] have predominantly 2- Dimensional [2D] effects, there are many situations in which 2D defect models do not suffice) e.g., tall layer bulks disrupting...

Dani, Sameer Manohar

2012-06-07

84

Characterization and Modeling of TSV Based 3-D Integrated Circuits

Characterization and Modeling of TSV Based 3-D Integrated Circuits Speaker: Prof. Ioannis Savidis Ioannis Savidis received a B.S.E. degree in Electrical and Computer Engineering and Biomedical Engineering

85

From the Biot-Savart Law to Ampere's Magnetic Circuital Law via Synthetic Differential Geometry

It is well known in classical electrodynamics that the magnetic field given by a current loop and the electric field caused by the corresponding dipoles in sheets are very similar, as far as we are far away from the loop, which enables us to deduce Ampere's magnetic circuital law from the Biot-Savart law easily. The principal objective in this paper is to show that synthetic differential geometry, in which nilpotent infinitesimals are in abundance, furnishes out a natural framework for the exquisite formulation and its demonstration. This similitude in heaven enables us to transit from the Biot-Savart law to Ampere's magnetic circuital law like a shot on earth.

Hirokazu Nishimura

2014-01-08

86

MODELLING OF CEMENT GRINDING CIRCUITS FOR PREDICTIVE CONTROL

A rst principles model of a cement grinding circuit is developed for the purpose of multi-variable model predictive control (MPC). The model is based on a series of mixed o w reactors with an ideal screen to model o w between the two chambers in the ball mill. The separator is modelled by eciency curves. Breakage of the particles is

Anker Degn; Jensen Sten; Bay Jrgensen; Michael Michelsen; Bodil Recke; John Bagterp Jrgensen

87

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

88

Digital quantum rabi and dicke models in superconducting circuits.

We propose the analog-digital quantum simulation of the quantum Rabi and Dicke models using circuit quantum electrodynamics (QED). We find that all physical regimes, in particular those which are impossible to realize in typical cavity QED setups, can be simulated via unitary decomposition into digital steps. Furthermore, we show the emergence of the Dirac equation dynamics from the quantum Rabi model when the mode frequency vanishes. Finally, we analyze the feasibility of this proposal under realistic superconducting circuit scenarios. PMID:25500735

Mezzacapo, A; Las Heras, U; Pedernales, J S; DiCarlo, L; Solano, E; Lamata, L

2014-01-01

89

A statistical MOSFET modeling method for CMOS integrated circuit simulation

A STATISTICAL MOSFET MODELING METHOD FOR CMOS IN'I'EGRATED CIRCUIT SIMULATION A Thesis by JIAN CHEN Submitted to the Office of Graduate Studies of Texas AE~M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August l 99'2 Major Sub ject: Electrical Engineering A STATISTICAL MOSFET MODELING METHOD FOR CMOS INTEGRATED CIRCUIT SIMULATION A Thesis by JIAN CHEN Approved as to style and content by: H. Maciej . Styblinski ) (Chair of Committee...

Chen, Jian

2012-06-07

90

Digital Quantum Rabi and Dicke Models in Superconducting Circuits

NASA Astrophysics Data System (ADS)

We propose the analog-digital quantum simulation of the quantum Rabi and Dicke models using circuit quantum electrodynamics (QED). We find that all physical regimes, in particular those which are impossible to realize in typical cavity QED setups, can be simulated via unitary decomposition into digital steps. Furthermore, we show the emergence of the Dirac equation dynamics from the quantum Rabi model when the mode frequency vanishes. Finally, we analyze the feasibility of this proposal under realistic superconducting circuit scenarios.

Mezzacapo, A.; Las Heras, U.; Pedernales, J. S.; Dicarlo, L.; Solano, E.; Lamata, L.

2014-12-01

91

Equivalent circuit models for resonant and PWM switches

The nonlinear switching mechanism in pulsewidth-modulated (PWM) and quasi-resonant converters is that of a three-terminal switching device which consists only of an active and a passive switch. An equivalent circuit model of this switching device describing the perturbations in the average terminal voltages and current is obtained. Through the use of this circuit model the analysis of pulsewidth modulated and

Vatche Vorperian; Richard Tymerski; F. C. Y. Lee

1989-01-01

92

Digital Quantum Rabi and Dicke Models in Superconducting Circuits

We propose the analog-digital quantum simulation of the quantum Rabi and Dicke models using circuit quantum electrodynamics (QED). We find that all physical regimes, in particular those which are impossible to realize in typical cavity QED setups, can be simulated via unitary decomposition into digital steps. Furthermore, we show the emergence of the Dirac equation dynamics from the quantum Rabi model when the mode frequency vanishes. Finally, we analyze the feasibility of this proposal under realistic superconducting circuit scenarios. PMID:25500735

Mezzacapo, A.; Las Heras, U.; Pedernales, J. S.; DiCarlo, L.; Solano, E.; Lamata, L.

2014-01-01

93

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

94

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

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

2009-01-01

95

Combination of Thermal Subsystems Modelled by Rapid Circuit Transformation

This paper will deal with the modeling-problem of combining thermal subsystems (e.g. a semiconductor module or package with a cooling radiator) making use of reduced models. The subsystem models consist of a set of Foster-type thermal equivalent circuits, which are only behavioral models. A fast al-gorithm is presented for transforming the Foster-type circuits in Cauer-circuits which have physical behavior and therefore allow for the construction of the thermal model of the complete system. Then the set of Cauer-circuits for the complete system is transformed back into Foster-circuits to give a simple mathematical representation and applicability. The transfor-mation algorithms are derived in concise form by use of recur-sive relations. The method is exemplified by modeling and measurements on a single chip IGBT package mounted on a closed water cooled radiator. The thermal impedance of the complete system is constructed from the impedances of the sub-systems, IGBT-package and radiator, and also the impedance of the package can be inferred from the measured impedance of the complete system.

Y. C. Gerstenmaier; W. Kiffe; G. Wachutka

2008-01-07

96

Parallel LC circuit model for multi-band absorption and preliminary design of radiative cooling.

We perform a comprehensive analysis of multi-band absorption by exciting magnetic polaritons in the infrared region. According to the independent properties of the magnetic polaritons, we propose a parallel inductance and capacitance(PLC) circuit model to explain and predict the multi-band resonant absorption peaks, which is fully validated by using the multi-sized structure with identical dielectric spacing layer and the multilayer structure with the same strip width. More importantly, we present the application of the PLC circuit model to preliminarily design a radiative cooling structure realized by merging several close peaks together. This omnidirectional and polarization insensitive structure is a good candidate for radiative cooling application. PMID:25607485

Feng, Rui; Qiu, Jun; Liu, Linhua; Ding, Weiqiang; Chen, Lixue

2014-12-15

97

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

98

Probabilistic Model of Fault Detection in Quantum Circuits

NASA Astrophysics Data System (ADS)

Since the introduction of quantum computation, several protocols (such as quantum cryptography, quantum algorithm, quantum teleportation) have established quantum computing as a superior future technology. Each of these processes involves quantum circuits, which are prone to different kinds of faults. Consequently, it is important to verify whether the circuit hardware is defective or not. The systematic procedure to do so is known as fault testing. Normally testing is done by providing a set of valid input states and measuring the corresponding output states and comparing the output states with the expected output states of the perfect (fault less) circuit. This particular set of input vectors are known as test set [6]. If there exists a fault then the next step would be to find the exact location and nature of the defect. This is known as fault localization. A model that explains the logical or functional faults in the circuit is a fault model. Conventional fault models include (i) stuck at faults, (ii) bridge faults, and (iii) delay faults. These fault models have been rigorously studied for conventional irreversible circuit. But with the advent of reversible classical computing and quantum computing it has become important to enlarge the domain of the study on test vectors.

Banerjee, A.; Pathak, A.

99

Circuit theory and model-based inference for landscape connectivity

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

100

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

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

101

A Distributed Circuit Model for Power-Line Communications

This paper presents a computational efficient distributed circuit model for broadband power-line communications (PLC) in the frequency range of 1 to 30 MHz. The model is derived based on the full wave approach and it takes into account the mutual coupling between the power lines, the effect of the ground plane and the discontinuity along the lines (e.g., PLC line

Wu Qiong Luo; Soon Yim Tan

2007-01-01

102

Simulations of a dynamical system model for electronic circuits

Models and numerical simulations are used to understand concepts of electronic circuits as well as to evaluate their performance without the actual need to build them. Today, they are mostly implemented by softwares that rely on numerical solutions of analytic models, which usually require a great amount of computational resources. In this paper, we propose an alternative particle dynamical system

Artur Aguila Marins; Davi Marco Lyra-Leite; Joao Paulo Carvalho Lustosa da Costa

2012-01-01

103

Bipolar transistor modeling of avalanche generation for computer circuit simulation

An avalanche generation model is developed and incorporated into computer circuit analysis programs SLIC and NICAP. A modified form of Miller's empirical expression for generation is found to agree well with measured data for Western Electric and commercial n-p-n transistors. Measurement techniques and parameter determination for the three model coefficients are discussed. Equation constraints appropriate for computer implementation are presented.

R. W. Dutton

1975-01-01

104

Some observations on modeling and control of cement grinding circuits

Based on system analysis and experimental data, a dynamic model of a closed-loop cement grinding circuit, which consists of a mixed set of algebraic and partial differential equations, is developed and validated. The model equations are solved numerically using the method of lines and the resulting simulation program is used to gain some insight into the process dynamics and to

M. Boulvin; A. Vande Wouwer; C. Renotte; M. Remy; R. Lepore

1998-01-01

105

Numerical modeling of magnetic devices

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

106

Punch-magnet delay eliminated by modification of circuit

NASA Technical Reports Server (NTRS)

Reduction of retardation by diode-resistor networks of the current-decay time of a punch magnet by connection of a Zener diode in series with the damping network increases the reliability of data on paper tape.

Cohn, C. E.

1969-01-01

107

Probabilistic modeling of noise transfer characteristics in digital circuits

NASA Astrophysics Data System (ADS)

Device scaling, the driving force of CMOS technology, led to continuous decrease in the energy level representing logic states. The resulting small noise margins in combination with increasing problems regarding the supply voltage stability and process variability creates a design conflict between efficiency and reliability. This conflict is expected to rise more in future technologies. Current research approaches on fault-tolerance architectures and countermeasures at circuit level, unfortunately, cause a significant area and energy penalty without guaranteeing absence of errors. To overcome this problem, it seems to be attractive to tolerate bit errors at circuit level and employ error handling methods at higher system levels. To do this, an estimate of the bit error rate (BER) at circuit level is necessary. Due to the size of the circuits, Monte Carlo simulation suffers from impractical runtimes. Therefore the needed modeling scheme is proposed. The model allows a probabilistic estimation of error rates at circuit level taking into account statistical effects ranging from supply noise and electromagnetic coupling to process variability within reasonable runtimes.

Schleifer, J.; Coenen, T.; Elkammar, A.; Noll, T. G.

2011-08-01

108

Monte Carlo Reliability Model for Microwave Monolithic Integrated Circuits

Monte Carlo Reliability Model for Microwave Monolithic Integrated Circuits Aris Christou Materials of the failure rate of each component due to interaction effects of the failed components. The Monte Carlo failure rates become nonconstant. The Monte Carlo technique is an appropriate methodology used to treat

Rubloff, Gary W.

109

Parasitic losses modeling of a series resonant converter circuit

This paper describes the formulation and verification of a SPICE macromodel for a practical series resonant converter circuit with parasitics. The macromodel is obtained by using a new proposed model of the power devices compared to the generic macromodel we have previously published. A 600 W series resonant converter has been built. Measurements of losses in each power device of

S. C. Wong; A. D. Brown; Y. S. Lee; S. W. Ng

1997-01-01

110

Modeling an optical magnetometer with electronic circuits Analysis and optimization

Modeling an optical magnetometer with electronic circuits Â Analysis and optimization Przemyslaw, University of California at Berkeley Berkeley, California 94720-7300, USA ABSTRACT: Optical magnetometers are typically obtained for ultra-low-field measurements, a group of optical magnetometers allows the detection

111

RF circuit block modeling via Kriging surrogates

The use of replacement metamodels (global surrogate models) has become commonplace as a cost effective alternative for performing complex high fidelity computer simulations. Due to their compact formulation and negligible evaluation time, global surrogate models are very useful tools for exploring the design space, what-if analysis, optimization, and sensitivity analysis. In addition, multiple surrogate models can be chained together to

Dirk Gorissen; Luciano De Tommasi; Wouter Hendrickx; Jeroen Croon; Tom Dhaene

2008-01-01

112

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

113

The critical current (I(c)) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous I(c) measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa2Cu3O(7-?)(YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure I(c) continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure I(c) of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular I(c) fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates. PMID:24182162

Zou, S N; Gu, C; Qu, T M; Han, Z

2013-10-01

114

NASA Astrophysics Data System (ADS)

The critical current (Ic) of high-temperature superconductor (HTS) tapes has to be examined not only for short samples, but also for the entire tape, because local weak points can possibly lead to the quenching of the whole HTS device. Some methods were reported for continuous Ic measurement along the length of a HTS tape, but few of them were applicable to tapes with magnetic substrates represented by YBa_2Cu_3O_{7-? } (YBCO)-coated conductors based on Ni5W alloy substrate by rolling assisted bi-axially textured substrate process. We previously presented a contact-free method using magnetic circuits to measure Ic continuously of long HTS tapes, namely the magnetic-circuit (MC) method. This method has been previously applied with high speed and resolution to measure Ic of HTS tapes with non-magnetic substrates, due to its resistance to noise aroused by mechanical vibration. In this work, its ability to measure HTS tapes with magnetic substrates is demonstrated both theoretically and experimentally. A 100 m long commercial YBCO tape based on Ni5W alloy substrate was measured and regular Ic fluctuations were discovered. The MC method can be a powerful tool for quality control of HTS tapes, especially for tapes with magnetic substrates.

Zou, S. N.; Gu, C.; Qu, T. M.; Han, Z.

2013-10-01

115

Application of Least Squares MPE technique in the reduced order modeling of electrical circuits

Application of Least Squares MPE technique in the reduced order modeling of electrical circuits an unsolvable reduced order model. This means that a model of an electrical circuit can become ill processes is also applied to the least-square reduced order model of the electrical circuit. The least

Eindhoven, Technische Universiteit

116

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

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

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

1990-07-02

117

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

118

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.

119

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

120

Modeling the Time-Harmonic Electromagnetic Emissions of Microwave Circuits

This paper presents a simple and practical method to reproduce and predict the time-domain behavior of the radiated electromagnetic fields of microwave circuits. The previously developed frequency-domain model is extended toward predicting the large-band electromagnetic radiations and thereby the time-harmonic fields. Fourier-series-based method is used in order to transform the frequency-domain near-field measurement data into time domain for digital applications.

Abhishek Ramanujan; Zouheir Riah; Anne Louis

2012-01-01

121

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

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

2011-05-01

122

AN INFINITE DIMENSIONAL DESCRIPTOR SYSTEM MODEL FOR ELECTRICAL CIRCUITS WITH TRANSMISSION LINES

AN INFINITE DIMENSIONAL DESCRIPTOR SYSTEM MODEL FOR ELECTRICAL CIRCUITS WITH TRANSMISSION LINES TIMO REIS Abstract. In this paper a model of linear electrical circuits with transmission lines is de. Nowadays, electrical circuits consist of a very large number ( 107 ) of components like resistors

Reis, Timo

123

A new mathematical model for facilitated mass transport in a polymeric membrane with a fixed-site carrier was developed by extending the single RC circuit model, which was derived by assuming concentration fluctuation and analogy between electron transport in a parallel resistor-capacitor (RC) circuit and mass transport in a facilitated transport membrane. Here, a series of parallel RC circuits was employed

Jae-Min Hong; Yong Soo Kang; Jyongsik Jang; Un Young Kim

1996-01-01

124

AN EQUIVALENT CIRCUIT MODEL AND POWER CALCULATIONS FOR THE APS SPX CRAB CAVITIES

/26/2011 Abstract An equivalent parallel resistor-inductor-capacitor (RLC) circuit with beam loading for a polarizedAN EQUIVALENT CIRCUIT MODEL AND POWER CALCULATIONS FOR THE APS SPX CRAB CAVITIES T. Berenc 1 as shown by 90deg. As in [1], an R/Q, which is useful for an equivalent circuit model for the dipole

Kemner, Ken

125

6.301 Solid-State Circuits Recitation 2: Device Physics and Modeling

6.301 Solid-State Circuits Recitation 2: Device Physics and Modeling Prof. Joel L. Dawson A few in these situations is clumsy at best. IC VE VC IB VB #12;6.301 Solid-State Circuits Recitation 2: Device Physics;6.301 Solid-State Circuits Recitation 2: Device Physics and Modeling Prof. Joel L. Dawson Page 3 Our linear

Dawson, Joel

126

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

127

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

128

Magnet Falling Through Ring Model

NSDL National Science Digital Library

The Magnet Falling Through Ring model shows the dynamics and the induced current when a magnet falls through a conducting ring. The current in the ring is computed by electromagnetic induction using to Faradayâs law and the induced emf is proportional to the negative of the rate of change of magnetic flux ?. The direction of the induced current is determined by Lenzâs law, the induced current produces magnetic field which tends to oppose the change in magnetic flux that induces such currents. The Magnet Falling Through Ring 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_mosem2_em_MagnetFallingThroughRing.jar file will run the program if Java is installed.

Franciscouembre

2010-09-03

129

Long-term Electro-Magnetic Robustness of Integrated Circuits: EMRIC research project

EMR in the scientific community and will contribute to develop EMR qualification procedures, EMR their lifetime, integrated circuits may be affected by harsh environmental conditions inducing internal. Integrating EMR models to simulation flow and developing EMR qualification procedures will help IC designer

Paris-Sud XI, UniversitÃ© de

130

Hierarchical Stochastic Simulation Algorithm for SBML Models of Genetic Circuits

This paper describes a hierarchical stochastic simulation algorithm, which has been implemented within iBioSim, a tool used to model, analyze, and visualize genetic circuits. Many biological analysis tools flatten out hierarchy before simulation, but there are many disadvantages associated with this approach. First, the memory required to represent the model can quickly expand in the process. Second, the flattening process is computationally expensive. Finally, when modeling a dynamic cellular population within iBioSim, inlining the hierarchy of the model is inefficient since models must grow dynamically over time. This paper discusses a new approach to handle hierarchy on the fly to make the tool faster and more memory-efficient. This approach yields significant performance improvements as compared to the former flat analysis method. PMID:25506588

Watanabe, Leandro H.; Myers, Chris J.

2014-01-01

131

Predictive CDM simulation approach based on tester, package and full integrated circuit modeling

The ESD sensitivity of integrated circuits with respect to the CDM is strongly dependent on the IC package, the substrate resistivity and the effectiveness of the ESD protection network. This paper presents a predictive CDM circuit simulation method based on tester, package and full integrated circuit modeling approach.

Dolphin Abessolo-Bidzo; Theo Smedes; Albert Jan Huitsing

2011-01-01

132

A two-port analogous circuit and SPICE model for Salmon's family of acoustic horns

A two-port analogous circuit and SPICE model for Salmon's family of acoustic horns W. Marshall simulator software such as SPICE simulation program with integrated circuit emphasis . An implementation they are used with electric circuit simulator software such as SPICE.1,2 The acronym SPICE stands for ``simula

Leach Jr.,W. Marshall

133

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

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

134

SELF-HEATING IN A COUPLED THERMO-ELECTRIC CIRCUIT-DEVICE MODEL

SELF-HEATING IN A COUPLED THERMO-ELECTRIC CIRCUIT-DEVICE MODEL MARKUS BRUNK AND ANSGAR JÂ¨UNGEL Abstract. The self-heating of a coupled thermo-electric circuit-semiconductor system is mod- eled. The three subsystems are coupled through thermo-electric, electric circuit-device, and thermal network

JÃ¼ngel, Ansgar

135

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

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

HAROLD SHICHMAN; DAVID A. HODGES

1968-01-01

136

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

NASA Astrophysics Data System (ADS)

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

Yang, Andrew T.

1986-08-01

137

A method based on the principle of the magnetic circuit is proposed and realized for contactless measurement of critical current (I(c)) of high temperature superconductor tapes. This method has two unique features: first, it eliminates noises caused by mechanical fluctuations and thus makes high speed and high stability measurement possible and second, adapts for both Bi(2)Si(2)Ca(2)Cu(3)O(x) (Bi2223) and YBa(2)Cu(3)O(7-x) (YBCO) tape, which even has a magnetic substrate. Theoretical analysis is given and an apparatus for the reel-to-reel measurement has been constructed, by which continuous inspection of I(c) uniformity of YBCO and Bi2223 tapes measured at different speeds is reported. PMID:20815626

Gu, C; Qu, T-M; Zou, S-N; Han, Z

2010-08-01

138

The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of their high force density, robustness, and accuracy. These linear PM motors are often heavily loaded during short intervals of high acceleration, so that magnetic saturation occurs. This paper models saturation and end effects in linear PM motors using magnetic circuit models. The saturating parts

Henk Polinder; Johannes G. Slootweg; Martin J. Hoeijmakers; John C. Compter

2003-01-01

139

Based on complex-variable analysis of a Fabry-Perot resonator as a multimode nonsymmetric two-port waveguide device, two versions of equivalent-circuit configurations are presented: Starting from a renewed study on single-mode two-pole circuits, we develop two respective multimode equivalent circuits of an almost identical configuration: one for the reflection coefficient and the other for the pass-through transmission coefficient. In the mathematics language of complex-variable analysis, the two models successfully "approximate" the two scattering coefficients through two "uniformly converging" partial-fraction series expansions. PMID:24562041

Song, G Hugh

2014-02-01

140

NASA Astrophysics Data System (ADS)

Objective. This work aims at flexible and practical pulse parameter control in transcranial magnetic stimulation (TMS), which is currently very limited in commercial devices. Approach. We present a third generation controllable pulse parameter device (cTMS3) that uses a novel circuit topology with two energy-storage capacitors. It incorporates several implementation and functionality advantages over conventional TMS devices and other devices with advanced pulse shape control. cTMS3 generates lower internal voltage differences and is implemented with transistors with a lower voltage rating than prior cTMS devices. Main results. cTMS3 provides more flexible pulse shaping since the circuit topology allows four coil-voltage levels during a pulse, including approximately zero voltage. The near-zero coil voltage enables snubbing of the ringing at the end of the pulse without the need for a separate active snubber circuit. cTMS3 can generate powerful rapid pulse sequences (\\lt 10 ms inter pulse interval) by increasing the width of each subsequent pulse and utilizing the large capacitor energy storage, allowing the implementation of paradigms such as paired-pulse and quadripulse TMS with a single pulse generation circuit. cTMS3 can also generate theta (50 Hz) burst stimulation with predominantly unidirectional electric field pulses. The cTMS3 device functionality and output strength are illustrated with electrical output measurements as well as a study of the effect of pulse width and polarity on the active motor threshold in ten healthy volunteers. Significance. The cTMS3 features could extend the utility of TMS as a research, diagnostic, and therapeutic tool.

Peterchev, Angel V.; D?Ostilio, Kevin; Rothwell, John C.; Murphy, David L.

2014-10-01

141

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

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

142

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

This report deals with the development of a delay-time model for timing simulation of large circuits consisting of Bipolar ECL(Emitter-Coupled Logic) and EFL (Emitter-Follower-Logic) networks. This model can provide adequate information on the performance of the circuits with a minimum expenditure of computation time. This goal is achieved by the use of proper circuit transient models on which analytical delay

Andrew T. Yang

1986-01-01

143

Modelling Mars' Magnetic Anomalies

An internal potential function was derived up to n=90 to improve upon an ongoing study of the crustal structure of the Martian magnetic field. The data included MGS magnetic observations below 200 km altitude taken during the two aerobraking phases (AB1 and AB2), the Science Phase Orbits (SPO), as well as higher altitude (370--440 km) data taken on the nightside

B. B. Ferguson; J. C. Cain; D. T. Mozzoni

2001-01-01

144

Astrocyte regulation of sleep circuits: experimental and modeling perspectives

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. PMID:22973222

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

2012-01-01

145

Circuit Modeling of the Electrical Impedance Part I: Neuromuscular Disease

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. PMID:23353926

Shiffman, C A; Rutkove, S B

2013-01-01

146

Compact modelling of Through-Silicon Vias (TSVs) in three-dimensional (3-D) integrated circuits

Modeling parasitic parameters of Through-Silicon-Via (TSV) structures is essential in exploring electrical characteristics such as delay and signal integrity (SI) of circuits and interconnections in three-dimensional (3-D) integrated circuits (ICs). This paper presents a complete set of self-consistent equations including self and coupling terms for resistance, capacitance and inductance of various TSV structures. Further, a reduced-order electrical circuit model is

Roshan Weerasekera; Matt Grange; Dinesh Pamunuwa; Hannu Tenhunen; Li-Rong Zheng

2009-01-01

147

A functional circuit model of interaural time difference processing.

Inputs from the two sides of the brain interact to create maps of interaural time difference (ITD) in the nucleus laminaris of birds. How inputs from each side are matched with high temporal precision in ITD-sensitive circuits is unknown, given the differences in input path lengths from each side. To understand this problem in birds, we modeled the geometry of the input axons and their corresponding conduction velocities and latencies. Consistent with existing physiological data, we assumed a common latency up to the border of nucleus laminaris. We analyzed two biological implementations of the model, the single ITD map in chickens and the multiple maps of ITD in barn owls. For binaural inputs, since ipsi- and contralateral initial common latencies were very similar, we could restrict adaptive regulation of conduction velocity to within the nucleus. Other model applications include the simultaneous derivation of multiple conduction velocities from one set of measurements and the demonstration that contours with the same ITD cannot be parallel to the border of nucleus laminaris in the owl. Physiological tests of the predictions of the model demonstrate its validity and robustness. This model may have relevance not only for auditory processing but also for other computational tasks that require adaptive regulation of conduction velocity. PMID:25185809

McColgan, Thomas; Shah, Sahil; Köppl, Christine; Carr, Catherine; Wagner, Hermann

2014-12-01

148

NASA Technical Reports Server (NTRS)

The fabrication yield of an on-chip modifiable redundant circuit design for a 100M bit serial shift register is evaluated. The yield model is a redundancy design in which there is a primary loop and a set of secondary loops which can be enabled/disabled without introducing blanks to the data stream. This function has a finite yield, the loop-modification yield factor, which must be greater than 0.9 to make the system more economical than the simple nonredundant design. It is further established that small loop capacities greatly degrade the yield because of the effect of the modification yield factor, while large loop capacities degrade the yield because of defects in the operating area. As the modification yield increases the optimum loop capacity decreases. An optimum value for the number of redundant loops exists for each loop capacity. Other factors that affect the yield are the garnet film and the processed circuit.

Bailey, R. F.; Reekstin, J. P.

1974-01-01

149

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

150

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

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

151

NASA Astrophysics Data System (ADS)

When a quench occurs in a superconducting magnet, excessive joule heating in normal region may damage the magnet. It is necessary to detect the quench as soon as possible and discharge magnetic energy stored in the magnet. The authors have presented a quench detection/protection system based on an active power method which detects the quench regardless of a self-inductive and mutual-inductive voltages and electromagnetic noise. In the conventional active power method, the inductive voltages are removed by cancel coils. In this paper, the authors propose a method to cancel an inductive voltage using a capacitor circuit. The quench detection/protection system becomes more precise and smaller than the conventional system through the capacitor circuit.

Nanato, N.; Otsuka, T.; Hesaka, S.; Murase, S.

2013-01-01

152

Abstract Based on the characteristics of cancer cells that cannot survive in an environment with temperature over 42?°C, a magnetic induction heating system for cancer treatment is developed in this work. First, the methods and analyses for designing the multi-cascaded coils magnetic induction hyperthermia system are proposed, such as internal impedance measurement of power generator, impedance matching of coils, and analysis of the system. Besides, characteristics of the system are simulated by a full-wave package for engineering optimization. Furthermore, by considering the safety factor of patients, a two-sectional needle is designed for hyperthermia. Finally, this system is employed to test the liver of swine in ex-vivo experiments, and through Hematoxylin and Eosin (H&E) stain and NADPH oxidase activity assay, the feasibility of this system is verified. PMID:25379959

Huang, Chi-Fang; Chao, Hsuan-Yi; Chang, Hsun-Hao; Lin, Xi-Zhang

2014-11-01

153

Lunar magnetism. [primordial core model

NASA Technical Reports Server (NTRS)

It is shown, for a very simple model of the moon, that the existence of a primordial core magnetic field would give rise to a present day nonzero dipole external field. In the investigation a uniformly magnetized core embedded in a permeable mantle is considered. The significance of the obtained results for the conclusions reported by Runcorn (1975) is discussed. Comments provided by Runcorn to the discussion are also presented.

Goldstein, M. L.

1975-01-01

154

Optimal design of a double-stator permanent magnet brushless machine with series magnetic circuit

This paper presents the optimal design of an 18-slot 8-pole double-stator permanent magnet brushless (DS-PMBL) machine. The key is to optimize the split ratio, namely the ratio of the inner-stator outside diameter to the outer-stator outside diameter, to achieve the maximum torque density under the same copper loss. Both the finite element analysis and experimental results are given to verify

Yubin Wang; Ming Cheng; Ying Fan; Xikai Sun; Wei Hua; K. T. Chau

2010-01-01

155

Transient modelling of single-electron transistors for efficient circuit simulation by SPICE

Transient modelling of single-electron transistors for efficient circuit simulation by SPICE Y simulation by SPICE. The developed model is based on a linearised equivalent circuit and the solution of a master equation is done by the programming capabilities of the SmartSpice. Exact delineation of several

Hwang, Sung Woo

156

AN ADAPTIVE FINITE ELEMENT METHOD FOR THE EDDY CURRENT MODEL WITH CIRCUIT/FIELD COUPLINGS

AN ADAPTIVE FINITE ELEMENT METHOD FOR THE EDDY CURRENT MODEL WITH CIRCUIT/FIELD COUPLINGS JUNQING for solving the eddy current model with voltage excitations for complicated three dimensional structures of the proposed method. Key words. Eddy current, circuit/field coupling, adaptivity, a posteriori error analysis

157

High Level Modeling of Channel-Based Asynchronous Circuits Using Verilog

In this paper we describe a method for modeling channel-based asynchronous circuits using Verilog HDL. We suggest a method to model CSP-like channels in Verilog HDL. This method also describes nonlinear pipelines and high- level channel timing properties, such as forward and backward latencies, minimum cycle time, and slack. Using Verilog enables us to describe the circuit at many levels

Arash Saifhashemi; Peter A. Beerel

2005-01-01

158

An optimal Strategy based on multilevel fuzzy comprehensive evaluation model in restricting short circuit current is presented. This method starts with establishing hierarchical structural diagram of short circuit current limitation measures and multilevel fuzzy comprehensive evaluation model based on Analytic Hierarchy Process. Then the weight values of different levels can be determined by setting up a judgment matrix. Finally, the

Wang Jiaming; Liu Wenying; Xie Chang; Li Jing; Wang Longzhen

2011-01-01

159

Modeling of soft magnetic composites

The electromagnetic properties of soft magnetic composites (SMCs) are studied based on a finite element model. In this approach, SMCs are modeled as an infinite array of hexagonal cylinders in two dimensions. Each cylinder is assumed to be saturable pure iron coated with a thin layer of binder or insulation. The array is excited by a current sheet or imposed

Yanhong Cui; G. B. Kliman

2004-01-01

160

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

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

161

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

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

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

2005-01-01

162

A Novel Prediction Method about Single Components of Analog Circuits Based on Complex Field Modeling

Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator) calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits' single components. At last, it uses particle filter (PF) to update parameters for the model and predicts remaining useful performance (RUP) of analog circuits' single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments. PMID:25147853

Tian, Shulin; Yang, Chenglin

2014-01-01

163

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., E-mail: amroldan@ugr.es; Roldán, J. B. [Department of Electronics and Computer Technology, University of Granada (Spain); Reig, C. [Department of Electronic Engineering, University of Valencia (Spain); Cardoso, S. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); Instituto Superior Técnico (IST), Av. Rovisco Pais, 1000-029 Lisbon (Portugal); Cardoso, F. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); Ferreira, R. [International Iberian Nanotechnology Laboratory, Braga (Portugal); Freitas, P. P. [INESC-MN and IN, Rua Alves Redol 9, 1000-029 Lisbon (Portugal); International Iberian Nanotechnology Laboratory, Braga (Portugal)

2014-05-07

164

Reliability-yield allocation for semiconductor integrated circuits: modeling and optimization

This research develops yield and reliability models for fault-tolerant semiconductor integrated circuits and develops optimization algorithms that can be directly applied to these models. Since defects cause failures in microelectronics systems...

Ha, Chunghun

2005-11-01

165

This paper presents a system identification technique for generating stable compact models of typical analog circuit blocks in radio frequency systems. The identification procedure is based on minimizing the model error ...

Bond, Bradley N.

166

Envelope Simulation by SPICE Compatible Models of Electric Circuits Driven by Modulated Signals

1 Envelope Simulation by SPICE Compatible Models of Electric Circuits Driven by Modulated Signals - SPICE compatible equivalent circuits were developed to facilitate the analysis and envelope simulation,4]. Still lacking thus far is a method that would facilitate envelope simulation by SPICE based general

167

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

This paper is an overview of the concepts and methodologies used to predict soft-error rates (SER) due to cosmic and high-energy particle radiation in integrated circuit chips. The paper emphasizes the need for the SER simulation using the actual chip circuit model which includes device, process, and technology parameters as opposed to using either the discrete device simulation or generic

G. R. Srinivasan

1996-01-01

168

Advanced modeling of planarization processes for integrated circuit fabrication

Planarization processes are a key enabling technology for continued performance and density improvements in integrated circuits (ICs). Dielectric material planarization is widely used in front-end-of-line (FEOL) processing ...

Fan, Wei, Ph. D. Massachusetts Institute of Technology

2012-01-01

169

Astrocyte regulation of sleep circuits: experimental and modeling perspectives

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 ...

Halassa, Michael M.

170

4th Grade Students Investigate Electric Circuits Through Construction and Illustration

NSDL National Science Digital Library

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

171

Circuit models and SPICE macro-models for quantum Hall effect devices

Quantum Hall effect (QHE) devices are a pillar of modern quantum electrical metrology. Electrical networks including one or more QHE elements can be used as quantum resistance and impedance standards. The analysis of these networks allows metrologists to evaluate the effect of the inevitable parasitic parameters on their performance as standards. This paper presents a systematic analysis of the various circuit models for QHE elements proposed in the literature, and the development of a new model. This last model is particularly suited to be employed with the analogue electronic circuit simulator SPICE. The SPICE macro-model and examples of SPICE simulations, validated by comparison with the corresponding analytical solution and/or experimental data, are provided.

Ortolano, Massimo

2015-01-01

172

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

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

173

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

174

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

175

GABAergic circuit dysfunction in the Drosophila Fragile X syndrome model.

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

176

Performance of Magnetic Hydro-Dynamic Pump in Lead-Bismuth Eutectic Target Circuit (TC-1)

Electromagnetic(EM) pumps or linear magneto-hydrodynamic (MHD) machines have been used in foundries for transporting molten metals and in sodium-cooled nuclear reactors for circulating coolant. While the use of MHD pumps for heavy liquid metals has not been fully investigated, they are beginning to be used and studied in R and D facilities in support of the development of advanced nuclear reactors and waste transmutation systems. One MHD pump was tested in its full operation range in the University of Nevada, Las Vegas (UNLV). This pump is the prime mover in the pilot molten lead-bismuth eutectic (LBE) target circuit TC-1 that is designed in Russia (IPPE, Obninsk, ISTCno559) to accommodate an 800 MeV proton beam power of 1 MW. Under the rated head of 0.99 meter in TC-1, the pump capacity is 15 m{sup 3}/hr. The hydraulic loss of the pump transport cross section was determined by measuring pressure drop and flow rate using piezometer and electro-magnetic flow meter in Russia. The relationship between input power and maximum head without circulation was obtained. As a result, the pump efficiency can be predicted based on the measured LBE flow rate and input power phase voltage and current. The performance curves of this MHD pump will be presented with the efficiency curves in this report. (authors)

Ma, J. [Department of Mechanical Engineering, University of Nevada, Las Vegas, 4505 Maryland Parkway, Mail Stop 454027, Las Vegas, NV 89154 (United States); Li, N. [Los Alamos National Laboratory, Lead-Alloy Coolant Technology and Materials Development MS H816 Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Ignatiev, S. [State Scientific Center of the Russian Federation-Institute for Physics and Power Engineering, Obninsk 249033 (Russian Federation); Kutanov, V. [Federal State Unitary Enterprise - Experimental and Design Organization 'GIDROPRESS', Podolsk 142103 (Russian Federation)

2006-07-01

177

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

178

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,

2013-06-01

179

NASA Astrophysics Data System (ADS)

This paper reports the electrical characterization and an equivalent circuit of a microhollow cathode discharge (MHCD) reactor in the self-pulsing regime. A MHCD reactor was prototyped for air plasma generation, and its current-voltage characteristics were measured experimentally in the self-pulsing regime for applied voltages from 2000 to 3000 V. The reactor was modeled as a capacitor in parallel with a variable resistor. A stray capacitance was also introduced to the circuit model to represent the capacitance of the circuit elements in the experimental setup. The values of the resistor and capacitors were recovered from experimental data, and the proposed circuit model was validated with independent experiments. Experimental data showed that increasing the applied voltage increased the current, self-pulsing frequency and average power consumption of the reactor, while it decreased the peak voltage. The maximum and the minimum voltages obtained using the model were in agreement with the experimental data within 2.5%, whereas the differences between peak current values were less than 1%. At all applied voltages, the equivalent circuit model was able to accurately represent the peak and average power consumption as well as the self-pulsing frequency within the experimental uncertainty. Although the results shown in this paper was for atmospheric air pressures, the proposed equivalent circuit model of the MHCD reactor could be generalized for other gases at different pressures.

Taylan, O.; Berberoglu, H.

2014-07-01

180

Recent advances in silicon nanofabrication have allowed the manipulation of spin qubits that are extremely isolated from noise sources, being therefore the semiconductor equivalent of single atoms in vacuum. We investigate the possibility of directly coupling an electron spin qubit to a superconducting resonator magnetic vacuum field. By using resonators modified to increase the vacuum magnetic field at the qubit location, and isotopically purified {sup 28}Si substrates, it is possible to achieve coupling rates faster than the single spin dephasing. This opens up new avenues for circuit-quantum electrodynamics with spins, and provides a pathway for dispersive read-out of spin qubits via superconducting resonators.

Tosi, Guilherme, E-mail: g.tosi@unsw.edu.au; Mohiyaddin, Fahd A.; Morello, Andrea, E-mail: a.morello@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Electrical Engineering and Telecommunications, UNSW Australia, Sydney, New South Wales 2052, Australia. (Australia); Huebl, Hans [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, D-85748 Garching (Germany); Nanosystems Initiative Munich (NIM), Schellingstr. 4, D-80799 Munich, Germany. (Germany)

2014-08-15

181

Finite element modeling of printed circuit board for structural analysis

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

M. Lee

1997-01-01

182

Equivalent circuit modeling of hybrid electric vehicle drive train

this objective, a methodology based on electrical analogies and transducers theory is presented in this work. Using the powerful circuit theory to solve multi-disciplinary problems is not revolutionary, but applied to the design of advanced vehicles, it brings a...

Routex, Jean-Yves

2012-06-07

183

Representing circuits more efficiently in symbolic model checking

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

184

An Equivalent Circuit Model for Electrostatic Energy Harvester utilized Energy Harvesting System

NASA Astrophysics Data System (ADS)

In this study, we report an equivalent circuit model of an electrostatic energy harvester for a SPICE circuit simulator. In order to simulate a harvesting system, the output power of the device is calculated in the simulator. The capacitance between the electrodes is obtained by FEM analysis by taking the fringing effect into account and the result is applied to a sub-circuit model for the simulator. Mechanical vibrations are converted into electricity by an equivalent circuit model of a mass-spring structure and an electrostatic energy harvester. The simulated output power and output waveform correspond with the measurement results of our electrostatic energy harvester. We also simulate the operation of a harvesting system connected with a power management IC.

Minami, K.; Fujita, T.; Sonoda, K.; Miwatani, N.; Kanda, K.; Maenaka, K.

2014-11-01

185

Applications of a new model of scalar hysteresis to a series ferroresonant circuit

In this paper the hysteretic behaviour of an iron core inductor is described by means of a new model based on a sequential algorithm. This model has been applied to study a series ferroresonant circuit. The simulations obtained using the proposed model are in good agreement with experimental results, as well as with the predictions of the classical Preisach model;

S. Bobbio; G. Miano; L. Verolino; C. Visone; E. Zamparelli

1994-01-01

186

Superior model for fault tolerance computation in designing nano-sized circuit systems

NASA Astrophysics Data System (ADS)

As CMOS technology scales nano-metrically, reliability turns out to be a decisive subject in the design methodology of nano-sized circuit systems. As a result, several computational approaches have been developed to compute and evaluate reliability of desired nano-electronic circuits. The process of computing reliability becomes very troublesome and time consuming as the computational complexity build ups with the desired circuit size. Therefore, being able to measure reliability instantly and superiorly is fast becoming necessary in designing modern logic integrated circuits. For this purpose, the paper firstly looks into the development of an automated reliability evaluation tool based on the generalization of Probabilistic Gate Model (PGM) and Boolean Difference-based Error Calculator (BDEC) models. The Matlab-based tool allows users to significantly speed-up the task of reliability analysis for very large number of nano-electronic circuits. Secondly, by using the developed automated tool, the paper explores into a comparative study involving reliability computation and evaluation by PGM and, BDEC models for different implementations of same functionality circuits. Based on the reliability analysis, BDEC gives exact and transparent reliability measures, but as the complexity of the same functionality circuits with respect to gate error increases, reliability measure by BDEC tends to be lower than the reliability measure by PGM. The lesser reliability measure by BDEC is well explained in this paper using distribution of different signal input patterns overtime for same functionality circuits. Simulation results conclude that the reliability measure by BDEC depends not only on faulty gates but it also depends on circuit topology, probability of input signals being one or zero and also probability of error on signal lines.

Singh, N. S. S.; Asirvadam, V. S.; Muthuvalu, M. S.

2014-10-01

187

A modeling approach of a magnetic amplifier

NASA Astrophysics Data System (ADS)

New soft magnetic materials made possible the use of the magnetic amplifier technology in designing competitive electric power supplies. This technology is used in the Swedish fighter aircraft Gripen, being also attractive for future more electrical aircraft systems due to the possibility to achieve a compact and robust design. A modeling approach of a magnetic amplifier based on the magnetic hysteresis of the core material is presented here for a common amorphous magnetic alloy. Also to be corresponded to.

Austrin, L.; Krah, J. H.; Engdahl, G.

2004-05-01

188

Equivalent-circuit model for vacuum ultraviolet irradiation of dielectric films

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

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

2012-05-15

189

A proper model for the partitioning of electrical circuits

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

190

Quasi-linear vacancy dynamics modeling and circuit analysis of the bipolar memristor.

The quasi-linear transport equation is investigated for modeling the bipolar memory resistor. The solution accommodates vacancy and circuit level perspectives on memristance. For the first time in literature the component resistors that constitute the contemporary dual variable resistor circuit model are quantified using vacancy parameters and derived from a governing partial differential equation. The model describes known memristor dynamics even as it generates new insight about vacancy migration, bottlenecks to switching speed and elucidates subtle relationships between switching resistance range and device parameters. The model is shown to comply with Chua's generalized equations for the memristor. Independent experimental results are used throughout, to validate the insights obtained from the model. The paper concludes by implementing a memristor-capacitor filter and compares its performance to a reference resistor-capacitor filter to demonstrate that the model is usable for practical circuit analysis. PMID:25390634

Abraham, Isaac

2014-01-01

191

Quasi-Linear Vacancy Dynamics Modeling and Circuit Analysis of the Bipolar Memristor

The quasi-linear transport equation is investigated for modeling the bipolar memory resistor. The solution accommodates vacancy and circuit level perspectives on memristance. For the first time in literature the component resistors that constitute the contemporary dual variable resistor circuit model are quantified using vacancy parameters and derived from a governing partial differential equation. The model describes known memristor dynamics even as it generates new insight about vacancy migration, bottlenecks to switching speed and elucidates subtle relationships between switching resistance range and device parameters. The model is shown to comply with Chua's generalized equations for the memristor. Independent experimental results are used throughout, to validate the insights obtained from the model. The paper concludes by implementing a memristor-capacitor filter and compares its performance to a reference resistor-capacitor filter to demonstrate that the model is usable for practical circuit analysis. PMID:25390634

Abraham, Isaac

2014-01-01

192

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

None

2012-01-09

193

Object-Oriented Modeling Of Power-Electronic Circuits Using Dymola

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

Hilding Elmqvist; François E. Cellier; Martin Otter

1994-01-01

194

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

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

195

Comparison of field and circuit generator models in single machine infinite bus system simulations

This paper compares the transient response of a finite element salient pole synchronous generator model connected to an infinite network bus to that of a system model based on an equivalent circuit representation of the machine. The characteristics and operating conditions of the two models are made equal as far as possible by thoroughgoing initiation and by using the finite

Johan Lidenholm; Martin Ranlöf; Urban Lundin

2010-01-01

196

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

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

197

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

198

SPOCK: A SPICE based circuit code for modeling pulsed power machines

SPICE is an industry standard electrical circuit simulation code developed by the University of California at Berkeley over the last twenty years. The authors have developed a number of new SPICE devices of interest to the pulsed power community: plasma opening switches, plasma radiation sources, bremsstrahlung diodes, magnetically insulated transmission lines, explosively driven flux compressors. These new devices are integrated into SPICE using S-Cubed`s MIRIAD technology to create a user-friendly circuit code that runs on Unix workstations or under Windows NT or Windows 95. The new circuit code is called SPOCK--``S-Cubed Power Optimizing Circuit Kit.`` SPOCK allows the user to easily run optimization studies by setting up runs in which any circuit parameters can be systematically varied. Results can be plotted as 1-D line plots, 2-D contour plots, or 3-D ``bedsheet`` plots. The authors demonstrate SPOCK`s capabilities on a color laptop computer, performing realtime analysis of typical configurations of such machines as HAWK and ACE4.

Ingermanson, R.; Parks, D. [Maxwell Labs., San Diego, CA (United States). S-Cubed Div.

1996-12-31

199

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

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

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

2012-01-01

200

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

201

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

202

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

203

A new circuit model of HgCdTe photodiode for SPICE simulation of integrated IRFPA

NASA Astrophysics Data System (ADS)

We propose a novel sub circuit model to simulate HgCdTe infrared photodiodes in a circuit simulator, like PSPICE. We have used two diodes of opposite polarity in parallel to represent the forward biased and the reverse biased behavior of an HgCdTe photodiode separately. We also connected a resistor in parallel with them to represent the ohmic shunt and a constant current source to represent photocurrent. We show that by adjusting the parameters in standard diode models and the resistor and current values, we could actually fit the measured data of our various HgCdTe photodiodes having different characteristics. This is a very efficient model that can be used for simulation of readout integrated circuit (ROIC) for HgCdTe IR photodiode arrays. This model also allows circuit level Monte Carlo simulation on a complete IRFPA at a single circuit simulator platform to estimate the non-uniformity for given processes of HgCdTe device fabrication and Si ROIC fabrication.

Saxena, Raghvendra Sahai; Saini, Navneet Kaur; Bhan, R. K.; Sharma, R. K.

2014-11-01

204

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a treatment for neurological and psychiatric disorders. Although the induced field is focused on a target region during rTMS, adjacent areas also receive stimulation at a lower intensity and the contribution of this perifocal stimulation to network-wide effects is poorly defined. Here, we examined low-intensity rTMS (LI-rTMS)-induced changes on a model neural network using the visual systems of normal (C57Bl/6J wild-type, n = 22) and ephrin-A2A5(-/-) (n = 22) mice, the latter possessing visuotopic anomalies. Mice were treated with LI-rTMS or sham (handling control) daily for 14 d, then fluorojade and fluororuby were injected into visual cortex. The distribution of dorsal LGN (dLGN) neurons and corticotectal terminal zones (TZs) was mapped and disorder defined by comparing their actual location with that predicted by injection sites. In the afferent geniculocortical projection, LI-rTMS decreased the abnormally high dispersion of retrogradely labeled neurons in the dLGN of ephrin-A2A5(-/-) mice, indicating geniculocortical map refinement. In the corticotectal efferents, LI-rTMS improved topography of the most abnormal TZs in ephrin-A2A5(-/-) mice without altering topographically normal TZs. To investigate a possible molecular mechanism for LI-rTMS-induced structural plasticity, we measured brain derived neurotrophic factor (BDNF) in the visual cortex and superior colliculus after single and multiple stimulations. BDNF was upregulated after a single stimulation for all groups, but only sustained in the superior colliculus of ephrin-A2A5(-/-) mice. Our results show that LI-rTMS upregulates BDNF, promoting a plastic environment conducive to beneficial reorganization of abnormal cortical circuits, information that has important implications for clinical rTMS. PMID:25100609

Makowiecki, Kalina; Harvey, Alan R; Sherrard, Rachel M; Rodger, Jennifer

2014-08-01

205

Repetitive transcranial magnetic stimulation (rTMS) is increasingly used as a treatment for neurological and psychiatric disorders. Although the induced field is focused on a target region during rTMS, adjacent areas also receive stimulation at a lower intensity and the contribution of this perifocal stimulation to network-wide effects is poorly defined. Here, we examined low-intensity rTMS (LI-rTMS)-induced changes on a model neural network using the visual systems of normal (C57Bl/6J wild-type, n = 22) and ephrin-A2A5?/? (n = 22) mice, the latter possessing visuotopic anomalies. Mice were treated with LI-rTMS or sham (handling control) daily for 14 d, then fluorojade and fluororuby were injected into visual cortex. The distribution of dorsal LGN (dLGN) neurons and corticotectal terminal zones (TZs) was mapped and disorder defined by comparing their actual location with that predicted by injection sites. In the afferent geniculocortical projection, LI-rTMS decreased the abnormally high dispersion of retrogradely labeled neurons in the dLGN of ephrin-A2A5?/? mice, indicating geniculocortical map refinement. In the corticotectal efferents, LI-rTMS improved topography of the most abnormal TZs in ephrin-A2A5?/? mice without altering topographically normal TZs. To investigate a possible molecular mechanism for LI-rTMS-induced structural plasticity, we measured brain derived neurotrophic factor (BDNF) in the visual cortex and superior colliculus after single and multiple stimulations. BDNF was upregulated after a single stimulation for all groups, but only sustained in the superior colliculus of ephrin-A2A5?/? mice. Our results show that LI-rTMS upregulates BDNF, promoting a plastic environment conducive to beneficial reorganization of abnormal cortical circuits, information that has important implications for clinical rTMS. PMID:25100609

Makowiecki, Kalina; Harvey, Alan R.; Sherrard, Rachel M.

2014-01-01

206

Structural Design and Analysis of the Model Coil for the Hybrid Magnet Superconducting Outsert

A model coil developed at the High Magnetic Field Laboratory, Chinese Academy of Sciences, will be wound with a Nb3Sn cable-in-conduit conductor (CICC). In this paper, we first introduce the model coil structure and its design requirements and then explicate the important components of the model coil structure, such as the preload structure, joint, cooling circuit, etc. Stress analyses of

Jiawu Zhu; Yinnian Pan; Wenge Chen; Yunfei Tan; Pengcheng Huang; Guangli Kuang

2011-01-01

207

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

208

Modeling of MOSFET parasitic capacitances, and their impact on circuit performance

We study layout dependent, parasitic capacitance contributions of MOSFETs with 3D simulations, and show that these contributions are for narrow and short devices comparable to intrinsic contributions. The performance of 65-nm technology is strongly affected by these components, and should therefore be modeled accurately in circuit simulations. We propose a methodology how to accurately and consistently model them in a

Judith Mueller; Rainer Thoma; Ertugrul Demircan; Christophe Bernicot; Andre Juge

2007-01-01

209

A Circuit Level Fault Model for Resistive Shorts of MOS Gate Oxide , Wangqi Qiu

A Circuit Level Fault Model for Resistive Shorts of MOS Gate Oxide Xiang Lu , Zhuo Li , Wangqi Qiu in MOS gate oxides that have zero-resistance. However, most shorts are resistive and may cause delay faults. In this paper, we propose a simple and realistic delay fault model for gate oxide shorts

Walker, Duncan M. "Hank"

210

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

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

211

Controlled-source analogous circuits and SPICE models for piezoelectric transducers

Transmission line analogous circuits for piezoelectric transducers are developed which employ controlled sources rather than the traditional transformer to model the coupling between the electrical and the mechanical systems. A novel method is used to derive each model that consists of adding a term that is equal to zero to one of the device electromechanical equations. When this is done,

W. Marshall Leach

1994-01-01

212

MODELS FOR AN ANESTHESIA BREATHING CIRCUIT Paul E. Bigeleisen + and Margaret Cheney ++

MODELS FOR AN ANESTHESIA BREATHING CIRCUIT Paul E. Bigeleisen + and Margaret Cheney ++ + Department of Anesthesia, St. Paul Ramsey Medical Center, St. Paul, MN 55101; perÂ manent address: DepartmentÂ4824. ABSTRACT This paper presents a mathematical model of a semiÂclosed anesthesia breathing cirÂ cuit

Cheney, Margaret

213

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

214

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. 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

215

Magnetic field diffusion modeling of a small enclosed firing system

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

216

Modeling spin magnetization transport in a spatially varying magnetic field

We present a framework for modeling the transport of any number of globally conserved quantities in any spatial configuration and apply it to obtain a model of magnetization transport for spin-systems that is valid in new regimes (including high-polarization). The framework allows an entropy function to define a model that explicitly respects the laws of thermodynamics. Three facets of the model are explored. First, it is expressed as nonlinear partial differential equations that are valid for the new regime of high dipole-energy and polarization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield. Differences among the three forms of the model are illustrated by numerical solution with parameters corresponding to a magnetic resonance force microscopy (MRFM) experiment. A family of analytic, steady-state solutions to the nonlinear equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. Finally, we analyze the separative quality of magnetization transport, and a steady-state solution for the magnetization is shown to be compatible with Fenske's separative mass transport equation.

Rico A. R. Picone; Joseph L. Garbini; John A. Sidles

2014-08-13

217

A flywheel energy storage system for use as an uninterruptible power supply at a utility substation to replace electrochemical batteries has been modeled. The model is developed using the Electro-Magnetic Transients Program (EMTP). Models for the flywheel, permanent magnet (synchronous) motor/generator, rectifiers and inverter have been included. Transient response for loss of power and clearing of a short circuit fault, as well as variation of load voltage due to the flywheel spinning down, is presented.

Weissbach, R.S.; Karady, G.G.; Farmer, R.G. [Arizona State Univ., Tempe, AZ (United States)

1996-11-01

218

A small-signal equivalent circuit for parallel-plate 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 T-C

2014-05-01

219

We present a homotopy continuation method (HCM) for finding multiple operating points of nonlinear circuits composed of devices modelled by using piecewise linear (PWL) representations. We propose an adaptation of the modified spheres path tracking algorithm to trace the homotopy trajectories of PWL circuits. In order to assess the benefits of this proposal, four nonlinear circuits composed of piecewise linear modelled devices are analysed to determine their multiple operating points. The results show that HCM can find multiple solutions within a single homotopy trajectory. Furthermore, we take advantage of the fact that homotopy trajectories are PWL curves meant to replace the multidimensional interpolation and fine tuning stages of the path tracking algorithm with a simple and highly accurate procedure based on the parametric straight line equation. PMID:25184157

Vazquez-Leal, H.; Jimenez-Fernandez, V. M.; Benhammouda, B.; Filobello-Nino, U.; Sarmiento-Reyes, A.; Ramirez-Pinero, A.; Marin-Hernandez, A.; Huerta-Chua, J.

2014-01-01

220

An analytic solar magnetic field model

We describe a simple analytic model for the magnetic field in the solar corona and interplanetary space which is appropriate to solar minimum conditions. The model combines an azimuthal current sheet in the equatorial plane with an axisymmetric multipole field representing the internal magnetic field of the Sun. The radial component of the field filling interplanetary space is approximately monopolar

M. Banaszkiewicz; W. I. Axford; J. F. McKenzie

1998-01-01

221

Thermodynamic ?T model of ultrafast magnetization dynamics

NASA Astrophysics Data System (ADS)

Exciting a ferromagnetic sample with an ultrashort laser pulse leads to a quenching of the magnetization on a subpicosecond time scale. On the basis of the equilibration of intensive thermodynamic variables, we establish a powerful model to describe the demagnetization process. We demonstrate that the magnetization dynamics is mainly driven by the equilibration of chemical potentials. The minimum of magnetization is revealed as a transient electron equilibrium state. Our method identifies the slowing down of ultrafast magnetization dynamics by a critical region within a magnetic phase diagram.

Mueller, B. Y.; Rethfeld, B.

2014-10-01

222

866 IEEE TRANSACTIONS ON MAGNETICS, VOL. 44, NO. 6, JUNE 2008 Dynamical Models for Eddy Current accurate dynamical models for representing eddy currents are studied. The simulation of the relay is provided. Index Terms--AC circuit breakers (CBs), eddy currents, magnetic hysteresis, optimization methods

Boyer, Edmond

223

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

224

Threshold flux-controlled memristor model and its equivalent circuit implementation

NASA Astrophysics Data System (ADS)

Modeling a memristor is an effective way to explore the memristor properties due to the fact that the memristor devices are still not commercially available for common researchers. In this paper, a physical memristive device is assumed to exist whose ionic drift direction is perpendicular to the direction of the applied voltage, upon which, corresponding to the HP charge-controlled memristor model, a novel threshold flux-controlled memristor model with a window function is proposed. The fingerprints of the proposed model are analyzed. Especially, a practical equivalent circuit of the proposed model is realized, from which the corresponding experimental fingerprints are captured. The equivalent circuit of the threshold memristor model is appropriate for various memristors based breadboard experiments.

Wu, Hua-Gan; Bao, Bo-Cheng; Chen, Mo

2014-11-01

225

Quantitative modeling and optimization of magnetic tweezers.

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

226

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

227

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

228

This paper presents a new model for the statistical analysis of the impact of Random Telegraph Noise (RTN) on circuit delay. This RTN-aware delay model have been developed using Pseudo RTN based on a Markov process with RTN statistical property. We have also measured RTNinduced delay fluctuation using a circuit matrix array fabricated in a 65nm process. Measured results include

Kyosuke Ito; Takashi Matsumoto; Shinichi Nishizawa; Hiroki Sunagawa; Kazutoshi Kobayashi; Hidetoshi Onodera

2011-01-01

229

Equivalent circuit model of traveling-wave maser slow-wave structures

NASA Technical Reports Server (NTRS)

An approach is presented for deriving transmission line equivalent circuits that can approximately model the S-parameter response of traveling wave maser slow wave structures. The technique is illustrated by computing the S-parameter responses of an X-band and S-band maser slow wave structure and comparing these with experimental measurements.

Shell, J.

1991-01-01

230

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

231

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

ERIC Educational Resources Information Center

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

Hirvonen, P. E.

2007-01-01

232

Mental Models of Elementary and Middle School Students in Analyzing Simple Battery and Bulb Circuits

ERIC Educational Resources Information Center

Written assessment items were developed to probe students' understanding of a variety of direct current (DC) resistive electric circuit concepts. The items were used to explore the mental models that grade 3-8 students use in explaining the direction of electric current and how electric current is affected by different configurations of simple…

Jabot, Michael; Henry, David

2007-01-01

233

Using the circuit theory to derive the mathematical models of AC machines. a review

Modeling of ac machines with predetermination of dynamic operation even in design stage appears a real necessity. On this base only, one can perform an accurate determination of parameters and constructive solutions of machine. In the paper, the hypotheses in which is possible a simple utilization of circuit theory, which operates with lumped parameters are underlined. It shows that is

Toma Dordea; Radu Munteanu; Aurel Campeanu

2011-01-01

234

Integrated circuits for sensing: compact models and implementation of silicon vision chips electronics is the ability to build on-chip complex heterogeneous systems. Designing systems incorporating sensors, analogue and digital electronics, and software is a complex task. Yet, verifying the correct

Baudoin, GeneviÃ¨ve

235

Design error diagnosis in digital circuits with stuck-at fault model

In this paper we describe in detail a new method for the single gate-level design error diagnosis in combinational circuits. Distinctive features of the method are hierarchical approach (the localizing procedure starts at the macro level and finishes at the gate level), use of stuck-at fault model (it is mapped into design error domain only in the end), and design

A. Jutman; R. Ubar

2000-01-01

236

Biological Circuit Models of Immune Regulatory Response: A Decentralized Control System

Biological Circuit Models of Immune Regulatory Response: A Decentralized Control System Matthew control based on recently discovered regulatory properties of the immune system. The immune system. INTRODUCTION The purpose of this paper is to improve our understanding of the immune system by understanding

Peet, Matthew M.

237

A circuit model for Biochemical Cell signaling receptor protein and phosphorylation cascade pathway

Communication between cells in multicellular organisms such as animals, humans and plants is essential for co-ordinating the organismic activities of fertilization, growth, survival and reproduction. This bio-chemical communication between trillions of cells in organisms can be more complex than the Internet. This paper develops a CMOS circuit model of signal reception and signal transduction within a cell in response to

S. M. Rezaul Hasan

2008-01-01

238

including transcription-translation machinery; however, all of the genetic material from host were carefully circuits as well as the expression of complete phage genome [21]. While elementary transcription and translation steps as well as degradation steps have been successfully modelled [12], the previous work focused

Murray, Richard M.

239

Understanding Layer 4 of the Cortical Circuit: A Model Based on Cat V1

Understanding Layer 4 of the Cortical Circuit: A Model Based on Cat V1 Kenneth D. Miller Depts: Understanding Cortical Layer 4 Address Correspondence To: Kenneth Miller Dept. of Physiology, UCSF 513 Parnassus, 2002 1 Abstract We review theoretical and experimental results on the processing of layer 4, the input

Columbia University

240

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

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

241

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

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. PMID:20016773

Yap, Jasmine J.; Miczek, Klaus A.

2009-01-01

242

The results of several micromechanical models are presented for predicting the properties of woven glass epoxy substrates used in multilayer circuit boards. Two new models are formulated and the predictions of the elastic moduli, Poisson`s ratios, and expansion coefficients are compared with the results of previously developed one and two dimensional models. The properties of several commercially pressed circuit boards are determined experimentally and compared with all of the different models. One of the newly proposed models, which does not use classical lamination theory, results in a significant improvement for the prediction of the Poisson`s ratios. Finally, parametric studies are performed to predict the influence of fabric geometry on the in-plane thermal expansion coefficients and elastic moduli. Optimal weaving parameters are identified which lead to improved dimensional stability.

Ockers, J.M.; Sottos, N.R. [Univ. of Illinois, Urbana, IL (United States)

1994-12-31

243

Modeling solar force-free magnetic fields

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

B. C. Low; Y. Q. Lou

1990-01-01

244

An enhanced BSIM modeling framework for selfheating aware circuit design

NASA Astrophysics Data System (ADS)

This work proposes a modeling framework to enhance the industry-standard BSIM4 MOSFET models with capabilities for coupled electro-thermal simulations. An automated simulation environment extracts thermal information from model data as provided by the semiconductor foundry. The standard BSIM4 model is enhanced with a Verilog-A based wrapper module, adding thermal nodes which can be connected to a thermal-equivalent RC network. The proposed framework allows a fully automated extraction process based on the netlist of the top-level design and the model library. A numerical analysis tool is used to control the extraction flow and to obtain all required parameters. The framework is used to model self-heating effects on a fully integrated class A/AB power amplifier (PA) designed in a standard 65 nm CMOS process. The PA is driven with +30 dBm output power, leading to an average temperature rise of approximately 40 °C over ambient temperature.

Schleyer, M.; Leuschner, S.; Baumgartner, P.; Mueller, J.-E.; Klar, H.

2014-11-01

245

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

246

A novel fault diagnosis model research for electronic circuit

Support vector machine (SVM) which overcomes the drawbacks of neural networks has been widely used for pattern recognition in recent years. A new optimization method for the fault diagnosis model is proposed. To overcome the deficiencies of low accuracy and high false alarm rate in fault diagnosis system, an integrated fault diagnosis model based on support vector regression and principal

JiCheng Liu; WenJie Tian

2010-01-01

247

Modeling spin magnetization transport in a spatially varying magnetic field

NASA Astrophysics Data System (ADS)

We present a framework for modeling the transport of any number of globally conserved quantities in any spatial configuration and apply it to obtain a model of magnetization transport for spin-systems that is valid in new regimes (including high-polarization). The framework allows an entropy function to define a model that explicitly respects the laws of thermodynamics. Three facets of the model are explored. First, it is expressed as nonlinear partial differential equations that are valid for the new regime of high dipole-energy and polarization. Second, the nonlinear model is explored in the limit of low dipole-energy (semi-linear), from which is derived a physical parameter characterizing separative magnetization transport (SMT). It is shown that the necessary and sufficient condition for SMT to occur is that the parameter is spatially inhomogeneous. Third, the high spin-temperature (linear) limit is shown to be equivalent to the model of nuclear spin transport of Genack and Redfield (1975) [1]. Differences among the three forms of the model are illustrated by numerical solution with parameters corresponding to a magnetic resonance force microscopy (MRFM) experiment (Degen et al., 2009 [2]; Kuehn et al., 2008 [3]; Sidles et al., 2003 [4]; Dougherty et al., 2000 [5]). A family of analytic, steady-state solutions to the nonlinear equation is derived and shown to be the spin-temperature analog of the Langevin paramagnetic equation and Curie's law. Finally, we analyze the separative quality of magnetization transport, and a steady-state solution for the magnetization is shown to be compatible with Fenske's separative mass transport equation (Fenske, 1932 [6]).

Picone, Rico A. R.; Garbini, Joseph L.; Sidles, John A.

2015-01-01

248

NASA Astrophysics Data System (ADS)

Models are important both in the development of physics itself and in teaching physics. Historically, the consensus models of physics have come to embody particular ontological assumptions and epistemological commitments. Educators have generally assumed that the consensus models of physics, which have stood the test of time, will also work well as teaching models, and for many topics this assumption is at least unproblematic and in many cases productive. However, in the case of electric circuits the consensus models are highly abstract and consequently inaccessible to beginning learners. Certain historically derived analogues for the consensus models are accepted in texts, but these are demonstrably ineffective for helping learners grasp the fundamental concepts of electric circuits. While awareness of other models circulates informally in the teaching community, these are not well documented in the science education literature and rarely referred to in authoritative texts, possibly because the models do not share the ontological assumptions and epistemological commitments that characterise consensus models. Consequently these models have not been subjected to a disciplined critique of their effectiveness for teaching purposes. In this paper I use criteria drawn from the science education literature to reflect on why I have found particular models valuable in teaching electric circuits. These criteria contrast with the epistemological and ontological features that characterise the consensus models of science, and my reflection leads me to attend explicitly to the ways in which meanings are created within physics. This suggests that all models, whether consensus models or not, can be used more knowingly for important educational ends.

Hart, Christina

2008-11-01

249

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

250

Equivalent Circuit Model for Thick Split Ring Resonators and Thick Spiral Resonators

A simple theoretical model which provides circuit parameters and resonance frequency of metallic thick resonators is presented. Two different topologies were studied: the original Pendry's SRR and spiral resonators of two and three turns. Theoretical computations of resonant frequencies are in good agreement with values obtained with a commercial electromagnetic solver. The model could be helpful for designing thick frequency selective surfaces (FSS) based on this types of resonators, so called metasurfaces.

Mancera, Laura Maria Pulido

2014-01-01

251

Analysis, modeling, and simulation of series-parallel resonant converter circuits

This paper presents a SPICE macromodel for a generic series-parallel resonant converter circuit. The model is derived from the averaged time-invariant state-space equations obtained from a Fourier transform. The conditions are derived under which all but the fundamental harmonic may be discarded, and the model developed based solely on the fundamental Fourier component. The single macromodel developed has a wide

Siu-Chung Wong; Andrew D. Brown

1995-01-01

252

This paper presents a system identification technique for generating stable compact models of typical analog circuit blocks in radio frequency systems. The identification procedure is based on minimizing the model error ...

Bond, Bradley N.

253

Vector spin modeling for magnetic tunnel junctions with voltage dependent effects

Integration and co-design of CMOS and spin transfer devices requires accurate vector spin conduction modeling of magnetic tunnel junction (MTJ) devices. A physically realistic model of the MTJ should comprehend the spin torque dynamics of nanomagnet interacting with an injected vector spin current and the voltage dependent spin torque. Vector spin modeling allows for calculation of 3 component spin currents and potentials along with the charge currents/potentials in non-collinear magnetic systems. Here, we show 4-component vector spin conduction modeling of magnetic tunnel junction devices coupled with spin transfer torque in the nanomagnet. Nanomagnet dynamics, voltage dependent spin transport, and thermal noise are comprehended in a self-consistent fashion. We show comparison of the model with experimental magnetoresistance (MR) of MTJs and voltage degradation of MR with voltage. Proposed model enables MTJ circuit design that comprehends voltage dependent spin torque effects, switching error rates, spin degradation, and back hopping effects.

Manipatruni, Sasikanth, E-mail: sasikanth.manipatruni@intel.com; Nikonov, Dmitri E.; Young, Ian A. [Exploratory Integrated Circuits, Components Research, Intel Corp., Hillsboro, Oregon 97124 (United States)

2014-05-07

254

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

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

255

SiC JFET Transistor Circuit Model for Extreme Temperature Range

NASA Technical Reports Server (NTRS)

A technique for simulating extreme-temperature operation of integrated circuits that incorporate silicon carbide (SiC) junction field-effect transistors (JFETs) has been developed. The technique involves modification of NGSPICE, which is an open-source version of the popular Simulation Program with Integrated Circuit Emphasis (SPICE) general-purpose analog-integrated-circuit-simulating software. NGSPICE in its unmodified form is used for simulating and designing circuits made from silicon-based transistors that operate at or near room temperature. Two rapid modifications of NGSPICE source code enable SiC JFETs to be simulated to 500 C using the well-known Level 1 model for silicon metal oxide semiconductor field-effect transistors (MOSFETs). First, the default value of the MOSFET surface potential must be changed. In the unmodified source code, this parameter has a value of 0.6, which corresponds to slightly more than half the bandgap of silicon. In NGSPICE modified to simulate SiC JFETs, this parameter is changed to a value of 1.6, corresponding to slightly more than half the bandgap of SiC. The second modification consists of changing the temperature dependence of MOSFET transconductance and saturation parameters. The unmodified NGSPICE source code implements a T(sup -1.5) temperature dependence for these parameters. In order to mimic the temperature behavior of experimental SiC JFETs, a T(sup -1.3) temperature dependence must be implemented in the NGSPICE source code. Following these two simple modifications, the Level 1 MOSFET model of the NGSPICE circuit simulation program reasonably approximates the measured high-temperature behavior of experimental SiC JFETs properly operated with zero or reverse bias applied to the gate terminal. Modification of additional silicon parameters in the NGSPICE source code was not necessary to model experimental SiC JFET current-voltage performance across the entire temperature range from 25 to 500 C.

Neudeck, Philip G.

2008-01-01

256

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

Baker, Pamela M.; Bair, Wyeth

2012-01-01

257

Modeling and optimization of permanent magnetic motors

This thesis develops analytic models for the prediction and optimization of radial-flux permanent magnet motor torque and efficiency. It also facilitates the design optimization of electromagnetically-powered rotorcraft ...

Pinkham, Andrew P

2008-01-01

258

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

259

Magnetic field decay in model SSC dipoles

We have observed that some of our model SSC dipoles have long time constant decays of the magnetic field harmonics with amplitudes large enough to result in significant beam loss, if they are not corrected. The magnets were run at constant current at the SSC injection field level of 0.3 tesla for one to three hours and changes in the magnetic field were observed. One explanation for the observed field decay is time dependent superconductor magnetization. Another explanation involves flux creep or flux flow. Data are presented on how the decay changes with previous flux history. Similar magnets with different Nb-Ti filament spacings and matrix materials have different long time field decay. A theoretical model using proximity coupling and flux creep for the observed field decay is discussed. 10 refs., 5 figs., 2 tabs.

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

1988-08-01

260

Performance modelling of pipelined circuit switching in multicomputer networks

Min,G. Sarbazi,H. Ould-Khaoua,M. Proceedings 8th Int. Symposium on Modeling, Analysis and Simulation of Computer and Telecommunication Systems (MASCOTS 2000), San Francisco, Aug. 29 - Sept. 1, 2000. pp 299-306 IEEE Computer Society Press

Min, G.; Sarbazi, H.; Ould-Khaoua, M.

261

A Novel Circuit Model of Nanotechnology-Enabled Inkjet-Printed Gas Sensors Using Multi-Wall Carbon-scale nanotechnology- enabled inkjet-printed modules. Index Terms -- Gas sensing, carbon nanotube, inkjet printing, equivalent circuit, nanotechnology. I. INTRODUCTION Due to their excellent mechanical and electronic

Tentzeris, Manos

262

Electronic circuits are ubiquitous; they are used in numerous industries including: the semiconductorProceedings of the 2nd FieldsÂMITACS Industrial Problem-Solving Workshop, 2008 Model Order Reduction for Electronic Circuits: Mathematical and Physical Approaches Problem Presenter: Wil Schilders

Shontz, Suzanne M.

263

Approaches for modeling magnetic nanoparticle dynamics

Magnetic nanoparticles are useful biological probes as well as therapeutic agents. There have been several approaches used to model nanoparticle magnetization dynamics for both Brownian as well as Néel rotation. The magnetizations are often of interest and can be compared with experimental results. Here we summarize these approaches including the Stoner-Wohlfarth approach, and stochastic approaches including thermal fluctuations. Non-equilibrium related temperature effects can be described by a distribution function approach (Fokker-Planck equation) or a stochastic differential equation (Langevin equation). Approximate models in several regimes can be derived from these general approaches to simplify implementation. PMID:25271360

Reeves, Daniel B; Weaver, John B

2014-01-01

264

A phenomenological constitutive model for magnetic shape memory alloys

A thermodynamics-based constitutive model is derived which predicts the nonlinear strain and magnetization response that magnetic shape memory alloys (MSMAs) exhibit when subjected to mechanical and magnetic loads. The model development is conducted...

Kiefer, Bjoern

2007-04-25

265

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

266

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

267

A comparative study of equivalent circuit models of ultracapacitors for electric vehicles

NASA Astrophysics Data System (ADS)

This paper comparatively examines three types of equivalent circuit models for ultracapacitors. They are the classic model, the multi-stage ladder model and the dynamic model. These models are consciously selected from the state-of-the-art lumped models reported in the literature. A test rig is developed and used to load the ultracapacitor and to collect the test data. The genetic algorithm (GA) is employed to extract the optimal model parameters based on the Hybrid Pulse Power Characterization (HPPC) test. The performance of these models is evaluated and compared by measuring the model complexity, accuracy, and robustness against 'unseen' data collected in the Dynamic Stress Test (DST) and a self-designed pulse test (SDP). The validation results show that the dynamic model has the best overall performance.

Zhang, Lei; Wang, Zhenpo; Hu, Xiaosong; Sun, Fengchun; Dorrell, David G.

2015-01-01

268

NASA Astrophysics Data System (ADS)

The continuing advancements in integrated circuit technology have placed new burdons on the circuit design engineer, who must rely extensively upon computer simulation to correctly predict circuit behavior. One challenge is to develop better modelling techniques to more accurately deal with complex p- n junction structures often used in modern VLSI designs. This paper presents an easily implemented method for deriving parameters which accurately model the behavior of MOS VLSI structures containing complex p- n junction capacitance components. The methodology is applicable to both planar and laterally diffused junctions, whether formed by direct ion implantation or by diffusion from a finite or infinite source. The theories behind the equations used and results of the application of this new technique are discussed. A flow chart for a fitter program based on the new method is presented and described. The corresponding program written for the TI-59 scientific programmable calculator is available. Final model parameters are given and are shown to produce a numerical capacitance model which is accurate to within 2%.

Pinkham, Raymond; Anderson, Daniel F.

1986-08-01

269

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

270

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

271

Multiband high-impedance surface absorbers with a single resistive sheet: Circuit theory model

We present a simple and efficient circuit model for the analysis of multi-band absorption characteristics of a stack of sub-wavelength grids (fishnets or patch arrays) in a layered environment with a single resistive sheet placed on top. It is shown that at low frequencies the resonances of total absorption occur, which are explained in terms of Fabry-P´ erot resonances associated

Yashwanth R. Padooru; Alexander B. Yakovlev; Chandra S. R. Kaipa; Francisco Medina; Francisco Mesa

2011-01-01

272

Highly localized Wannier functions for the efficient modeling of Photonic Crystal Circuits

We present a novel approach for the accurate and efficient modeling of photonic crystal-based integrated optical circuits. Within this approach, the electromagnetic field is expanded into an orthogonal basis of highly localized Wannier functions, which reduces Maxwell's equations to low-rank eigenvalue problems (for defect mode and waveguide dispersion calculations) or to sparse systems of linear equations (for transmission\\/reflection calcu- lations

Matthias Schillingerab; Sergei F. Mingaleeva; Daniel Hermann; Kurt Buscha

273

Parallel Algorithm for Simulation of Circuit and One-Way Quantum Computation Models

In this paper we present the software to simulate circuits and one-way quantum computation models in parallel environments\\u000a build from PC workstations connected by the standard Ethernet network. We describe the main vector state transformation and\\u000a its application to one and multi-qubit gate application process. We also show the realisation of the measurement process in\\u000a non-standard bases. We present a

Marek Sawerwain

2007-01-01

274

The interplay of plasticity and adaptation in neural circuits: a generative model

Multiple neural and synaptic phenomena take place in the brain. They operate over a broad range of timescales, and the consequences of their interplay are still unclear. In this work, I study a computational model of a recurrent neural network in which two dynamic processes take place: sensory adaptation and synaptic plasticity. Both phenomena are ubiquitous in the brain, but their dynamic interplay has not been investigated. I show that when both processes are included, the neural circuit is able to perform a specific computation: it becomes a generative model for certain distributions of input stimuli. The neural circuit is able to generate spontaneous patterns of activity that reproduce exactly the probability distribution of experienced stimuli. In particular, the landscape of the phase space includes a large number of stable states (attractors) that sample precisely this prior distribution. This work demonstrates that the interplay between distinct dynamical processes gives rise to useful computation, and proposes a framework in which neural circuit models for Bayesian inference may be developed in the future. PMID:25400577

Bernacchia, Alberto

2014-01-01

275

Global Solar Photospheric Magnetic Field Modeling (Invited)

NASA Astrophysics Data System (ADS)

Estimation of the global photospheric magnetic field distribution is currently difficult since only approximately half of the solar surface is magnetically observed at any given time. With the solar rotational period relative to Earth at approximately 27 days, these global maps include observed data that are more than 13 days old. Data assimilation between old and new observations can result in spatial polarity discontinuities that result in monopole signals. To help minimize these large discontinuities we have developed the ADAPT (Air Force Data Assimilative Photospheric flux Transport) model, which incorporates data assimilation using an Ensemble Least Squares (EnLS) estimation method with photospheric magnetic flux transport. The ADAPT transport model evolves the solar magnetic flux for an ensemble of realizations using different parameter values for rotational, meridional, and super-granular diffusive transport processes. New data assimilative methods, along with recent progress to incorporate solar farside and subsurface nearside data inferred from helioseismology, will be discussed in this presentation.

Henney, C. J.; Arge, C. N.; Toussaint, W.; Gonzalez-Hernandez, I. E.; Koller, J.; Godinez, H. C.; Macdonald, G. A.

2013-12-01

276

The slender solar tachocline: a magnetic model

A model for the sharp transition from differential rotation in the solar convection zone to rigid rotation in the radiative interior is presented. Differential rotation in the radiative zone is shown to be quenched efficiently by an internal magnetic field. The poloidal field amplitude, B_0, is the input parameter for our model which determines the transition layer thickness and the

G. Rudiger; L. L. Kitchatinov

1997-01-01

277

We study a complexity model of quantum circuits analogous to the standard (acyclic)Boolean circuit model. It is shown that any function computable in polynomial time by aquantum Turing machine has a polynomial-size quantum circuit. This result also enablesus to construct a universal quantum computer which can simulate, with a polynomialfactor slowdown, a broader class of quantum machines than that considered

Andrew Chi-chih Yao

1993-01-01

278

Parametric, nonparametric and parametric modelling of a chaotic circuit time series

The determination of a differential equation underlying a measured time series is a frequently arising task in nonlinear time series analysis. In the validation of a proposed model one often faces the dilemma that it is hard to decide whether possible discrepancies between the time series and model output are caused by an inappropriate model or by bad estimates of parameters in a correct type of model, or both. We propose a combination of parametric modelling based on Bock's multiple shooting algorithm and nonparametric modelling based on optimal transformations as a strategy to test proposed models and if rejected suggest and test new ones. We exemplify this strategy on an experimental time series from a chaotic circuit where we obtain an extremely accurate reconstruction of the observed attractor.

J. Timmer; H. Rust; W. Horbelt; H. U. Voss

2000-09-19

279

Analytical dynamic modeling of a cantilever IPMC actuator based on a distributed electrical circuit

NASA Astrophysics Data System (ADS)

Ionic polymer-metal composite (IPMC) has a wide range of applications in robotics, biomedical devices and artificial muscles. The modeling of the IPMC actuator is a multi-physics task as it involves electricity, chemistry, dynamics and control. Due to its complexity and its nonlinearity, IPMC modeling is difficult and its behavior is still not fully agreed upon by researchers. In this paper, a dynamic model of a cantilever IPMC actuator based on a distributed RC electrical circuit is developed. The RC transmission line theory is used to derive the simple analytical impedance and actuation model of an IPMC actuator. This method permits us to identify the current and voltage as functions of polymer length and frequency. First, an infinite-dimensional impedance model is developed and then replaced with a simple second-order electro-mechanical model using the Golubev method. The proposed modeling approach is validated using existing experimental data.

Moeinkhah, Hossein; Rezaeepazhand, Jalil; Akbarzadeh, Alireza

2013-05-01

280

SPICE modelling of magnetic tunnel junctions written by spin-transfer torque

NASA Astrophysics Data System (ADS)

Spintronics aims at extending the possibility of conventional electronics by using not only the charge of the electron but also its spin. The resulting spintronic devices, combining the front-end complementary metal oxide semiconductor technology of electronics with a magnetic back-end technology, employ magnetic tunnel junctions (MTJs) as core elements. With the intent of simulating a circuit without fabricating it first, a reliable MTJ electrical model which is applicable to the standard SPICE (Simulation Program with Integrated Circuit Emphasis) simulator is required. Since such a model was lacking so far, we present a MTJ SPICE model whose magnetic state is written by using the spin-transfer torque effect. This model has been developed in the C language and validated on the Cadence Virtuoso Platform with a Spectre simulator. Its operation is similar to that of the standard BSIM (Berkeley Short-channel IGFET Model) SPICE model of the MOS transistor and fully compatible with the SPICE electrical simulator. The simulation results obtained using this model have been found in good accord with those theoretical macrospin calculations and results.

Guo, W.; Prenat, G.; Javerliac, V.; El Baraji, M.; de Mestier, N.; Baraduc, C.; Diény, B.

2010-06-01

281

Magnetization model for a Heusler alloy

NASA Astrophysics Data System (ADS)

Close to room temperature, the off-stoichiometric Ni50Mn35In15 Heusler alloy is known to undergo a first-order magnetostructural transition. This paper presents a new model that closely mimics the magnetic behavior of the virgin curve and that of the M-H loops within the temperature range where the alloy undergoes the first-order transition. The virgin curve and the M-H loops relevant to the model were measured at 280 K. Since our data show that 280 K is above the start of the transition, it implies that at this temperature the alloy is in a mixed state. The mixed state refers the presence of two distinct magnetic states. The model and mechanism we propose to explain the complex magnetic behavior of the virgin curve and of the M-H loops pertain to the action of the applied field on the transition between the two magnetic states. Both the model and the proposed mechanism provide new insight about the complex magnetic behavior displayed by the Ni50Mn35In15 alloy within the first-order transition.

Provenzano, Virgil; Della Torre, Edward; Bennett, Lawrence H.

2013-05-01

282

A plastic corticostriatal circuit model of adaptation in perceptual decision making

The ability to optimize decisions and adapt them to changing environments is a crucial brain function that increase survivability. Although much has been learned about the neuronal activity in various brain regions that are associated with decision making, and about how the nervous systems may learn to achieve optimization, the underlying neuronal mechanisms of how the nervous systems optimize decision strategies with preference given to speed or accuracy, and how the systems adapt to changes in the environment, remain unclear. Based on extensive empirical observations, we addressed the question by extending a previously described cortico-basal ganglia circuit model of perceptual decisions with the inclusion of a dynamic dopamine (DA) system that modulates spike-timing dependent plasticity (STDP). We found that, once an optimal model setting that maximized the reward rate was selected, the same setting automatically optimized decisions across different task environments through dynamic balancing between the facilitating and depressing components of the DA dynamics. Interestingly, other model parameters were also optimal if we considered the reward rate that was weighted by the subject's preferences for speed or accuracy. Specifically, the circuit model favored speed if we increased the phasic DA response to the reward prediction error, whereas the model favored accuracy if we reduced the tonic DA activity or the phasic DA responses to the estimated reward probability. The proposed model provides insight into the roles of different components of DA responses in decision adaptation and optimization in a changing environment. PMID:24339814

Hsiao, Pao-Yueh; Lo, Chung-Chuan

2013-01-01

283

Testing the Model of Oscillating Magnetic Traps

NASA Astrophysics Data System (ADS)

The aim of this paper is to test the model of oscillating magnetic traps (the OMT model), proposed by Jakimiec and Tomczak ( Solar Phys. 261, 233, 2010). This model describes the process of excitation of quasi-periodic pulsations (QPPs) observed during solar flares. In the OMT model energetic electrons are accelerated within a triangular, cusp-like structure situated between the reconnection point and the top of a flare loop as seen in soft X-rays. We analyzed QPPs in hard X-ray light curves for 23 flares as observed by Yohkoh. Three independent methods were used. We also used hard X-ray images to localize magnetic traps and soft X-ray images to diagnose thermal plasmas inside the traps. We found that the majority of the observed pulsation periods correlates with the diameters of oscillating magnetic traps, as was predicted by the OMT model. We also found that the electron number density of plasma inside the magnetic traps in the time of pulsation disappearance is strongly connected with the pulsation period. We conclude that the observations are consistent with the predictions of the OMT model for the analyzed set of flares.

Szaforz, ?.; Tomczak, M.

2015-01-01

284

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

285

NASA Technical Reports Server (NTRS)

The details of the efforts to synthesize a control-compatible multivariable model of a liquid nitrogen cooled, gaseous nitrogen operated, closed circuit, cryogenic pressure tunnel are presented. The synthesized model was transformed into a real-time cryogenic tunnel simulator, and this model is validated by comparing the model responses to the actual tunnel responses of the 0.3 m transonic cryogenic tunnel, using the quasi-steady-state and the transient responses of the model and the tunnel. The global nature of the simple, explicit, lumped multivariable model of a closed circuit cryogenic tunnel is demonstrated.

Balakrishna, S.; Goglia, G. L.

1979-01-01

286

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

287

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

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

288

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

289

Design metal-dot based QCA circuits using SPICE model Rui Tang, Fengming Zhang, Yong-Bin Kim *

U N C O R R EC TED PR O O F Design metal-dot based QCA circuits using SPICE model Rui Tang form 26 December 2005; accepted 10 January 2006 Abstract This paper proposes a SPICE model development methodology for quantum-dot cellular automata (QCA) cells and presents a SPICE model for QCA cells. The model

Ayers, Joseph

290

Finite element analysis in electromagnetic systems-accounting for electric circuits

Two approaches for the numerical simulation of electromagnetic systems, accounting for electric circuit equations, are presented. First, the indirect coupled model, which permits the simulation of synchronous machines fed by controlled inverters with moderate calculation time is considered. Second, a direct coupled model where the magnetic and electric circuit equations (2-D or 3-D) are solved simultaneously is developed. This approach

Francis Piriou; Adel Razek

1993-01-01

291

Coupled wave model for large magnet coils

NASA Technical Reports Server (NTRS)

A wave coupled model based on field theory is evolved for analysis of fast electromagnetic transients on superconducting coils. It is expected to play a useful role in the design of protection methods against damage due to high voltages or any adverse effects that might arise from unintentional transients. The significant parameters of the coil are identified to be the turn to turn wave coupling coefficients and the travel time of an electromagnetic disturbance around a single turn. Unlike circuit theoretic inductor, the coil response evolves in discrete steps having durations equal to this travel time. It is during such intervals that high voltages are likely to occur. The model also bridges the gap between the low and high ends of the frequency spectrum.

Gabriel, G. J.

1980-01-01

292

Variation of the global electric circuit and Ionospheric potential in a general circulation model

NASA Astrophysics Data System (ADS)

general circulation model of the atmosphere and ocean INMCM4.0 (Institute of Numerical Mathematics Coupled Model) is used for modeling the global electric circuit short-time variability and long-term evolution. The ionospheric potential parameterization is proposed which takes into account quasi-stationary currents of electrified clouds (including thunderstorms) as principal contributors into the DC global circuit. The diurnal, seasonal, and interannual variations of the ionospheric potential (IP) are modeled and compared with available data. Numerical simulations suggest that the IP decreases in the mean with the global warming due to increasing greenhouse gas emission (by about 10% during the 21st century if the Representative Concentration Pathway 8.5 Wm-2 scenario is assumed). At the same time the lightning flash rate increases with global warming by about 5 fl/s per degree. Interannual IP variability is low and does not exceed 1% of the mean value, being tightly correlated with the mean sea surface temperature in the Pacific Ocean (El Niño area).

Mareev, E. A.; Volodin, E. M.

2014-12-01

293

A circuit simulation analysis and diagnosis methods are used to diagnose instruments in detail when they give apparently abnormal readings. In this paper, a new simulator for analyzing the modeling of important circuits under SACs(severe accident conditions) has been designed. The realization of a one body system by using a one order command system in the LabVIEW and Pspice was used instead of a complex two body system. The program shows the output data from the circuit modeling according to a one order command system. The procedure for the simulator design was divided into two steps, of which the first step was the design of the diagnosis methods, and the second step was a circuit simulator for the signal processing tool and the special signal analysis tool. It has three main functions which are a signal processing tool, an accident management tool, and an additional guide from the initial screen. (authors)

Kil-Mo, Koo; Sang-Baik, Kim; Hee-Dong, Kim [Department of Thermal-Hydraulic Safety Research Team, KAERI, 150 Dukjin-dong, Yuseong, Daejeon, 305-353 (Korea, Republic of); Hae-Yong, Kang [Semiconductor Research Institute, Korea University, Daejeon (Korea, Republic of)

2006-07-01

294

This paper presents a method to automatically generate compact symbolic performance models of analog circuits with no prior specification of an equation template. The approach takes SPICE simulation data as input, which enables modeling of any nonlinear circuits and circuit characteristics. Genetic programming is applied as a means of traversing the space of possible symbolic expressions. A grammar is specially designed to constrain the search to a canonical form for functions. Novel evolutionary search operators are designed to exploit the structure of the grammar. The approach generates a set of symbolic models which collectively provide a tradeoff between error and model complexity. Experimental results show that the symbolic models generated are compact and easy to understand, making this an effective method for aiding understanding in analog design. The models also demonstrate better prediction quality than posynomials.

Mcconaghy, Trent; Gielen, Georges

2011-01-01

295

1H-magnetic resonance spectroscopy imaging and diffusion tensor imaging were performed in 19 patients with mild depression and in 13 controls. The mean age of the patients was 31 years. The mean Hamilton depression score of the patients was 22.5 ± 13.2. N-acetylaspartate, choline and creatine concentrations and the average diffusion coefficient and fractional anisotropy values were measured in the bilateral hippocampus, striatum, thalamus and prefrontal deep white matter. Compared with the control group, the mild depressed patients had: (1) a higher choline/creatine ratio and a negative correlation between the choline/creatine ratio and the average diffusion coefficient in the hippocampus; (2) a lower choline/creatine ratio and a higher fractional anisotropy in the striatum; (3) a lower fractional anisotropy and a positive correlation between the fractional anisotropy and the choline/creatine ratio in the prefrontal deep white matter; and (4) a higher average diffusion coefficient and a positive correlation between the choline/creatine ratio and the N-acetylaspartate/creatine ratio in the thalamus, as well as positive correlation between the choline/creatine ratio and Hamilton depression scores. These data suggest evidence of abnormal connectivity in neurofibrotic microstructures and abnormal metabolic alterations in the limbic-cortical-striatal-pallidal-thalamic neural circuit in patients with mild depression.

Chen, Shaoqiong; Lai, Lisha; Kang, Zhuang; Luo, Xiao; Zhang, Jiansheng; Li, Jianfang

2012-01-01

296

NASA Astrophysics Data System (ADS)

New power conversion systems that offer promise to transform electricity grids into unified interactive supply networks require high-resistivity soft-magnetic materials to allow for switching of magnetic materials at frequencies approaching 100 kHz for power transformation in the megawatt range. Amorphous and nanocomposite soft-magnetic materials, which represent the state of the art in terms of high power densities and low losses at high frequencies, have resistivities that depend on the structures and spatial distributions of multiple phases in thin ribbons. We present a multiphase resistivity model applicable to nanocomposite materials by considering an equivalent circuit approach considering paths through an amorphous, crystalline, and growth inhibitor shell phase. We detail: (a) identification of amorphous, crystalline, and shell phases; (b) consideration of the role of the morphology of each phase in an equivalent circuit model for the resistance; (c) a two-band model for the Fe/Co composition dependence of the resistivity in crystalline and amorphous phases; (d) a virtual bound state model for resistivity to explain increased resistivity due to early transition-metal growth inhibitors in the shell surrounding the nanocrystalline phase; and (e) disorder effects on amorphous phase resistivity. Experimental design and results for systems of interest in high-frequency power transformation are discussed in the context of our model including: (a) techniques for measurements of cross-section and density, (b) four-point probe and surface resistivity measurements, and (c) measurements in Fe- and Co-rich systems comparing amorphous and nanocomposite materials.

DeGeorge, V.; Shen, S.; Ohodnicki, P.; Andio, M.; McHenry, M. E.

2014-01-01

297

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

298

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

299

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

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

300

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

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

301

Numerical calculations are shown to reproduce the main results of recent experiments involving nonlocal spin control in quantum dots [Craig et al., Science 304, 565 (2004).]. In particular, the experimentally reported zero-bias-peak splitting is clearly observed in our studies. To understand these results, a simple 'circuit model' is introduced and shown to qualitatively describe the experiments. The main idea is that the splitting originates in a Fano antiresonance, which is caused by having one quantum dot side connected in relation to the current's path. This scenario provides an explanation of the results of Craig et al. that is an alternative to the RKKY proposal, also addressed here.

Martins, G. B. [Oakland University, Rochester, MI; Busser, Carlos A [ORNL; Al Hassanieh, Khaled A [ORNL; Anda, E. V. [Pontificia Universidade, Brazil; Moreo, Adriana [ORNL; Dagotto, Elbio R [ORNL

2006-01-01

302

Nonlinear Solar Dynamo Model with Magnetic Helicity

Variations of the sunspot number are important indicators of the solar activity cycles. The sunspot formation is a result of a dynamo process inside the Sun, which is far from being understood. We use simple dynamical models of the dynamo process to simulate the magnetic field evolution and investigate general properties of the sunspot number variations during the solar cycles. We have found that the classical Parker's model with a standard kinetic helicity quenching cannot represent the typical profiles of the solar-cycle variations of the sunspot number, and also does not give chaotic solutions. For modeling of the solar cycle properties we use a nonlinear dynamo model of Kleeorin and Ruzmaikin (1982), which takes into account dynamics of the turbulent magnetic helicity. We have obtained a series of periodic and chaotic solutions for different layers of the convective zone. The solutions qualitatively reproduce some basic observational features of the solar cycle properties, in particular, the relationship between the growth time and the cycle amplitude. Also, on the longer time scale the dynamo model with the magnetic helicity has intermittent solutions, which may be important for modeling long-term variations of the solar cycles.

I. N. Kitiashvili; A. G. Kosovichev

2009-02-11

303

The magnetic fields of Uranus and Neptune: Methods and models

We present new models of the magnetic fields of Uranus and Neptune, based on data provided by the Voyager II magnetic field experiment. We find the simplest models that satisfy the data, and use the observed surface heat flow as a constraint on the magnetic field structure. Our models are similar to the previously described Q3 and O8 models far

Richard Holme; Jeremy Bloxham

1996-01-01

304

Quark matter under strong magnetic fields in chiral models

The chiral model is used to describe quark matter under strong magnetic fields and is compared to other models, the MIT bag model and the two-flavor Nambu-Jona-Lasinio model. The effect of vacuum corrections due to the magnetic field is discussed. It is shown that if the magnetic-field vacuum corrections are not taken into account explicitly, the parameters of the models should be fitted to low-density meson properties in the presence of the magnetic field.

Rabhi, Aziz [Centro de Fisica Computacional, Department of Physics, University of Coimbra, P-3004-516 Coimbra (Portugal); Laboratoire de Physique de la Matiere Condensee, Faculte des Sciences de Tunis, Campus Universitaire, Le Belvedere-1060 (Tunisia); Providencia, Constanca [Centro de Fisica Computacional, Department of Physics, University of Coimbra, P-3004-516 Coimbra (Portugal)

2011-05-15

305

Glass micropipettes are widely used to record neural activity from single neurons or clusters of neurons extracellularly in live animals. However, to date, there has been no comprehensive study of noise in extracellular recordings with glass micropipettes. The purpose of this work was to assess various noise sources that affect extracellular recordings and to create model systems in which novel micropipette neural amplifier designs can be tested. An equivalent circuit of the glass micropipette and the noise model of this circuit, which accurately describe the various noise sources involved in extracellular recordings, have been developed. Measurement schemes using dead brain tissue as well as extracellular recordings from neurons in the inferior colliculus, an auditory brain nucleus of an anesthetized gerbil, were used to characterize noise performance and amplification efficacy of the proposed micropipette neural amplifier. According to our model, the major noise sources which influence the signal to noise ratio are the intrinsic noise of the neural amplifier and the thermal noise from distributed pipette resistance. These two types of noise were calculated and measured and were shown to be the dominating sources of background noise for in vivo experiments. PMID:25133158

Chen, Chang Hao; Pun, Sio Hang; Mak, Peng Un; Vai, Mang I; Klug, Achim; Lei, Tim C.

2014-01-01

306

The calculational modeling of impurity mass transfer in NPP circuits with liquid metal coolant

NASA Astrophysics Data System (ADS)

The authors create three levels of models (one-dimensional, two-dimensional and three-dimensional) for estimation of impurity mass transfer in sodium circuits units as well as applicable computational programs. In the one-dimensional model the flow path elements are simulated by annular channels. The Lagrange coordinate system is used in the mathematical description of processes in channels. The two-dimensional model is based on the porous body approximation and enables one to simulate global spatial distributions of coolant flow velocity fields, coolant and fuel rods temperatures, and concentration distribution of transferred substances. The mathematical description of passive multicomponent impurity transfer is carried out using the system of the differential equations with sources and impurity diffusion, written for each component. The equations are solved by the finite-difference method. The developed version of the three-dimensional code is based on a general approach of the spatial three-dimensional description of thermal-hydraulic and mass-transfer processes in fuel rod bundles. The determining system of finite-difference equations of hydrodynamics and heat exchange is obtained using the control volume approach. As a result of the performed calculations, valuable data on corrosion products transfer in the primary circuit of the BN-600 reactor are obtained.

Alexeev, V.; Kozlov, F.; Kumaev, V.; Orlova, E.; Klimanova, Yu; Torbenkova, I.

2008-02-01

307

It has been proposed that multiple frequency bioelectrical impedance models of the human body should include an inductive property for the circulatory system, the inductor circuit model (ICM), and that such a model, when coupled with a new method of data analysis, can improve the predictive power of multiple frequency bioelectrical impedance analysis (MFBIA). This hypothesis was tested using MFBIA

L Ward; B H Cornish; N I Paton; B J Thomas

1999-01-01

308

We present a new high-resolution model of the Earth's global atmospheric electric circuit (GEC) represented by an equivalent electrical network. Contributions of clouds to the total resistance of the atmosphere and as current generators are treated more realistically than in previous GEC models. The model of cloud current generators is constructed on the basis of the ISCCP cloud data and

A. Odzimek; M. Lester; M. Kubicki

2010-01-01

309

Magnetic Core Model of a Midfrequency Resistance Spot Welding Transformer

This paper deals with the analytically described iron core model of a midfrequency resistance spot welding transformer. This model considers eddy currents, hysteresis, and the saturation effect in a laminated iron core. The proposed model is simple, based on parameters that can be obtained from a data sheet, and is easy to integrate into the circuit model of the transformer.

Vojko Podlogar; Beno Klopcic; Gorazd Stumberger; Drago Dolinar

2010-01-01

310

NASA Technical Reports Server (NTRS)

The GEM 2008 modeling challenge efforts are expanding beyond comparing in-situ measurements in the magnetosphere and ionosphere to include the computation of indices to be compared. The Dst index measures the largest deviations of the horizontal magnetic field at 4 equatorial magnetometers from the quiet-time background field and is commonly used to track the strength of the magnetic disturbance of the magnetosphere during storms. Models can calculate a proxy Dst index in various ways, including using the Dessler-Parker Sckopke relation and the energy of the ring current and Biot-Savart integration of electric currents in the magnetosphere. The GEM modeling challenge investigates 4 space weather events and we compare models available at CCMC against each other and the observed values of Ost. Models used include SWMF/BATSRUS, OpenGGCM, LFM, GUMICS (3D magnetosphere MHD models), Fok-RC, CRCM, RAM-SCB (kinetic drift models of the ring current), WINDMI (magnetosphere-ionosphere electric circuit model), and predictions based on an impulse response function (IRF) model and analytic coupling functions with inputs of solar wind data. In addition to the analysis of model-observation comparisons we look at the way Dst is computed in global magnetosphere models. The default value of Dst computed by the SWMF model is for Bz the Earth's center. In addition to this, we present results obtained at different locations on the Earth's surface. We choose equatorial locations at local noon, dusk (18:00 hours), midnight and dawn (6:00 hours). The different virtual observatory locations reveal the variation around the earth-centered Dst value resulting from the distribution of electric currents in the magnetosphere during different phases of a storm.

Rastaetter, Lutz; Kuznetsova, Maria; Hesse, Michael; Chulaki, Anna; Pulkkinen, Antti; Ridley, Aaron J.; Gombosi, Tamas; Vapirev, Alexander; Raeder, Joachim; Wiltberger, Michael James; Mays, M. L.; Fok, Mei-Ching H.; Weigel, Robert S.; Welling, Daniel T.

2010-01-01

311

Full vector model for magnetization in sediments

NASA Astrophysics Data System (ADS)

Sediments provide a continuous record of past geomagnetic field variations. Although it is theoretically possible to get both the direction and intensity of the geomagnetic field from sediment records, the mechanism is not fully understood. Previous workers have postulated that flocculation plays an important role in detrital remanent magnetism (DRM). Flocs are porous, loose and highly fragile aggregates of microscopic clay particles and their behavior in a viscous medium is likely to be different than single particles of magnetic minerals. In order to understand the role of flocculation in sediment magnetization, we carried out a set of redeposition experiments at different field intensities and a quasi-constant field inclination of 45°. We present here a simple numerical model of flocculation, incorporating both magnetic and hydrodynamic torques to explain the experimental data. At small floc sizes DRM acquisition is likely to be non-linear in field strengths comparable to the Earth's, but the sediments may be able to record the directions accurately. With increasing floc sizes sediments may retain a record of the intensity that is linearly related to the applied field or a direction parallel to the applied field, but are unlikely to do both at the same time. Also, the majority of the magnetic particles in the sediments may not be contributing significantly towards the net DRM and any bulk normalizing parameter may be unsuitable if the depositional environment has changed over the depositional period.

Mitra, Ritayan; Tauxe, Lisa

2009-09-01

312

Chaotic Electric Circuit Explorer

NSDL National Science Digital Library

The Chaotic Electric Circuit Explorer Model simulation enables the user to explore the properties and behavior of two electrical circuits with known chaotic behavior. The two circuits are Chua's circuit and an autonomous relaxation oscillator (ARO). The simulation has four modes. The user may run a circuit with either preset or user-selected initial conditions to observe the time-dependence of voltage across specific capacitors and a plot of the phase space of these capacitors' voltages against one another. The Chaotic Electric Circuit Explorer 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_comp_phys_circuit_chaos.jar file will run the program if Java is installed.

Marcil, Greg

2011-07-26

313

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

314

A Global Circuit Tool for Modeling Lightning Indirect Effects on Aircraft

NASA Astrophysics Data System (ADS)

The topic of this study is electromagnetic environment and electromagnetic interference (EMI) effects, specifically the modeling of lightning indirect effects on aircraft electrical systems present on embedded and highly exposed equipments, such as nose landing gear (NLG) and nacelles, 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.

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

315

An Equivalent Circuit Modeling of Discharge Current Injected in Contact with an ESD-gun

NASA Astrophysics Data System (ADS)

The transient electromagnetic (EM) fields caused by an electrostatic discharge (ESD) have broadband frequency spectra, which cause serious failure to high-tech information equipment. From this perspective, an ESD testing for the EM immunity of the equipment is specified by the IEC 61000-4-2, in which the detailed waveform of the discharge current injected onto the IEC recommended Pellegrini target in contact with an ESD-gun is prescribed for calibration. However, the factors for determining the current waveform remain unclear, and thus the IEC prescribed current waveform is unlikely to be injected into actual equipment. In this study, based on the structure of an ESD-gun, an equivalent circuit modeling is proposed for analyzing the discharge current injected onto a 50-? SMA connector instead of the IEC target that has frequency-dependent transmission characteristics. Its validity is confirmed by comparing the calculated current waveform with the measured result. The proposed circuit modeling is also validated from measurement of the discharge current injected onto a transmission-line by the ESD-gun.

Fujiwara, Osamu; Tanaka, Hideyuki; Yamanaka, Yukio

316

Modeling integrated photovoltaic–electrochemical devices using steady-state equivalent circuits

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

317

Modeling quantum noise for efficient testing of fault-tolerant circuits

Understanding fault-tolerant properties of quantum circuits is important for designing large-scale quantum information processors. In particular, simulating properties of encoded circuits is a crucial tool for investigating ...

Magesan, Easwar

318

Polymeric self-resettable circuit protection devices have been manufactured for many years with an extrusion based process. These devices add negligible resistance to a circuit at normal power operating conditions but ...

Hardy, Joseph T., 1978-

2005-01-01

319

Magnetic field gradients from the ST-5 constellation: Improving magnetic and thermal models. Busby (2007), Magnetic field gradients from the ST-5 constellation: Improving magnetic and thermal] Satellite constellations enable the efficient collection of in situ measurements over large volumes of space

Busby, Cathy

320

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

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

321

NASA Technical Reports Server (NTRS)

The equivalent representation of brakes and coupling by lumped circuits is investigated. Analytical equations are derived for relating the indices of the transients to the parameters of the equivalent circuits for arbitrary rotor speed. A computer algorithm is given for the calculations.

Guseynov, F. G.; Abbasova, E. M.

1977-01-01

322

Finite element modeling of multipolar buckets with permanent magnets

NASA Astrophysics Data System (ADS)

The efficiency of the multipolar bucket is determined largely by the trapping of energetic electrons in the magnetic field. The calculation of fields generated by permanent magnets is not trivial, as the field strength depends on the energy stored in the magnetic field and the demagnetization curve of the permanent magnets. The magnetic field properties of multipolar buckets are modeled for a variety of magnet dimensions and number of columns using a finite element modeling software package. The energy of the magnetic field is combined with demagnetization curves for permanent magnets to predict the magnetic field strength. Field strength, decay length, and leak width are determined for a variety of chamber sizes, magnet dimensions and strengths. These parameters are also computed for experiments on optimization of multipolar bucket plasma confinement(Leung, K. N. et al.,Phys.Lett.51A(1975)490). Criteria for optimizing the magnetic bucket configuration are proposed.

Vukovic, Mirko

1999-10-01

323

NASA Astrophysics Data System (ADS)

Through-silicon-via (TSV) to TSV crosstalk noise is one of the key factors affecting the signal integrity of three-dimensional integrated circuits (3D ICs). Based on the frequency dependent equivalent electrical parameters for the TSV channel, an analytical crosstalk noise model is established to capture the TSV induced crosstalk noise. The impact of various design parameters including insulation dielectric, via pitch, via height, silicon conductivity, and terminal impedance on the crosstalk noise is analyzed with the proposed model. Two approaches are proposed to alleviate the TSV noise, namely, driver sizing and via shielding, and the SPICE results show 241 mV and 379 mV reductions in the peak noise voltage, respectively.

Qian, Li-Bo; Zhu, Zhang-Ming; Xia, Yin-Shui; Ding, Rui-Xue; Yang, Yin-Tang

2014-03-01

324

Investigation of galvanic-coupled intrabody communication using the human body circuit model.

Intrabody Communication (IBC) is a technique that uses the human body as a transmission medium for electrical signals to connect wearable electronic sensors and devices. Understanding the human body as the transmission medium in IBC paves way for practical implementation of IBC in body sensor networks. In this study, we propose a model for galvanic coupling-type IBC based on a simplified equivalent circuit representation of the human upper arm. We propose a new way to calculate the electrode-skin contact impedance. Based on the model and human experimental results, we discuss important characteristics of galvanic coupling-type IBC, namely, the effect of tissues, anthropometry of subjects, and electrode configuration on signal propagation. We found that the dielectric properties of the muscle primarily characterize the received signal when receiver electrodes are located close to transmitter electrodes. When receiver and transmitter electrodes are far apart, the skin dielectric property affects the received signal. PMID:25014932

Kibret, Behailu; Seyedi, MirHojjat; Lai, Daniel T H; Faulkner, Micheal

2014-07-01

325

Circuit model for the inverse Z-pinch wire array switch.

A 0D circuit code is introduced to study the wire array switch concept introduced in. It has been implemented and researched at Imperial College. An exploding wire array, the switch, is in parallel with the load, an imploding wire array. Most of the current flows in the exploding array until it expands and becomes highly resistive. The 0D code contains simple models of Joule energy deposition and plasma expansion for W and Al wires. The purpose of the device is to produce fast Z-pinch implosion, below 100ns on MAGPIE and the Sandia Z machine. Self and mutual inductances are taken into consideration as well as the rocket model for wire ablation. The switch characteristics of the exploding array are prescribed and tuned up to agree with MAGPIE shots. The dependence of the device on the configuration of the arrays is studied and scaling to ZR conditions is explored.

Waisman, Eduardo Mario; Cuneo, Michael Edward; Harvey-Thompson, A. (The Blackett Laboratory, Imperial College, London SW7 2BW, UK); Lebedev, Sergey V. (The Blackett Laboratory, Imperial College, London SW7 2BW, UK)

2010-06-01

326

Avalanche Photodetectors Fabricated in Standard CMOS Process Myung-Jae Lee, Student Member, IEEE, Hyo model for CMOS- compatible avalanche photodetectors. The equivalent circuit model includes an inductive component for avalanche delay, a cur- rent source for photogenerated carriers, and several components

Choi, Woo-Young

327

Biomedical engineering applications of ionic polymer–metal composites such as motion devices for endoscopy, pumps, valves, catheter navigation mechanisms and spinal pressure sensors make it important to properly model IPMCs for engineering design. In particular, IPMC continuum models and their electric equivalent circuit representation are critical to a more efficient design of IPMC devices. In this paper, we propose a new

P. J. Costa Branco; J. A. Dente

2006-01-01

328

Multipole Models of the Earth's Magnetic Field

NASA Astrophysics Data System (ADS)

To develop a mathematical model of rotational motion of an artificial satellite about its center of mass under the action of various forces (magnetic, Lorentz, etc.) caused by the geomagnetic field, it is necessary to know the induction of the Earth's magnetic field (EMF) as a function of the radius vector of a given point in the near-Earth space. Because the EMF possesses a complex structure and the above-mentioned functional dependence is unavailable in explicit analytic form, a set of approximate models of the EMF should be used. The simplest such model-a right dipole (aligned with the axis of rotation)-does not enable one to reveal in detail the influence of diurnal EMF rotation on the rotational motion of a satellite. The next EMF approximation-an inclined magnetic dipole-does not suffer from the above-mentioned drawback. However, it is shown that not all corrections to the magnetic induction of the EMF of the same order of magnitude are taken into account in the course of transformation from the model of aligned dipole to the model of inclined dipole. So, to develop the EMF model accurately accounting for the absence of axial symmetry of the EMF with respect to the axis of diurnal rotation of the Earth, in general, the effect of the quadrupole component of the geomagnetic potential on the EMF induction (and, probably, even the components of higher orders) must be taken into consideration. By using the International Geomagnetic Reference Field IGRF-2000, the multipole models of the EMF, corresponding to quadrupole, octupole, and higher-order approximations, were constructed and studied in this work. The EMF potential is expressed in terms of its multipole tensors. As a result, projections of the induction and induction gradient of EMF in the center of mass of the satellite onto the axes of the orbital coordinate system can be written in convenient and concise form. The expressions for the first four multipole tensors through the known geomagnetic constants are found. A method for estimating the reliability of these models is put forward, and the regions of applicability of the quadrupole and octupole models are drawn on the plane of orbital parameters.

Tikhonov, A. A.; Petrov, K. G.

2002-05-01

329

Simplified Modeling of Active Magnetic Regenerators

NASA Astrophysics Data System (ADS)

Active magnetic regenerator (AMR) refrigeration is an alternative technology to conventional vapor-compression refrigerators that has the potential to operate at higher efficiencies. Based on the magnetocaloric effect, this technology uses the magnetization and demagnetization of environmentally neutral solid refrigerants to produce a cooling effect. To become competitive however, a large amount of research into the optimal device configurations, operating parameters and refrigerants is still needed. To aid in this research, a simplified model for predicting the general trends of AMR devices at a low computational cost is developed. The derivation and implementation of the model for an arbitrary AMR is presented. Simulations from the model are compared to experimental results from two different devices and show good agreement across a wide range of operating parameters. The simplified model is also used to study the impacts of Curie temperature spacing, material weighting and devices on the performance of multilayered regenerators. Future applications of the simplified AMR model include costing and optimization programs where the low computational demand of the model can be fully exploited.

Burdyny, Thomas

330

MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS

MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES@umich.edu Received 24 November 2010 Accepted 16 June 2011 The eddy current loss in the magnets of permanent magnet- mium-iron-boron (NdFeB), and slot/tooth harmonics, there is eddy current loss generated inside

Mi, Chunting "Chris"

331

This paper presents a complete circuit-compatible compact model for single-walled carbon-nanotube field-effect transistors (CNFETs) as an extension to Part 1 of this two-part paper. For the first time, a universal circuit-compatible CNFET model including the practical device nonidealities is implemented with HSPICE. In addition to the nonidealities included in the companion paper, this paper includes the elastic scattering in the

Jie Deng; H.-S. Philip Wong

2007-01-01

332

Two-population model for anomalous low-temperature magnetism in geometrically frustrated magnets

Strongly geometrically frustrated magnets are unlike other magnetic materials in that the magnetic susceptibility of such materials appears to follow the Curie-Weiss law down to temperatures well below the Weiss temperature. We present an explanation for this anomalous behavior through a phenomenological model of two separate spin populations. The predictions of this model quantitatively describe the experimental data for a

P. Schiffer; I. Daruka

1997-01-01

333

STDP Installs in Winner-Take-All Circuits an Online Approximation to Hidden Markov Model Learning

In order to cross a street without being run over, we need to be able to extract very fast hidden causes of dynamically changing multi-modal sensory stimuli, and to predict their future evolution. We show here that a generic cortical microcircuit motif, pyramidal cells with lateral excitation and inhibition, provides the basis for this difficult but all-important information processing capability. This capability emerges in the presence of noise automatically through effects of STDP on connections between pyramidal cells in Winner-Take-All circuits with lateral excitation. In fact, one can show that these motifs endow cortical microcircuits with functional properties of a hidden Markov model, a generic model for solving such tasks through probabilistic inference. Whereas in engineering applications this model is adapted to specific tasks through offline learning, we show here that a major portion of the functionality of hidden Markov models arises already from online applications of STDP, without any supervision or rewards. We demonstrate the emergent computing capabilities of the model through several computer simulations. The full power of hidden Markov model learning can be attained through reward-gated STDP. This is due to the fact that these mechanisms enable a rejection sampling approximation to theoretically optimal learning. We investigate the possible performance gain that can be achieved with this more accurate learning method for an artificial grammar task. PMID:24675787

Kappel, David; Nessler, Bernhard; Maass, Wolfgang

2014-01-01

334

STDP installs in Winner-Take-All circuits an online approximation to hidden Markov model learning.

In order to cross a street without being run over, we need to be able to extract very fast hidden causes of dynamically changing multi-modal sensory stimuli, and to predict their future evolution. We show here that a generic cortical microcircuit motif, pyramidal cells with lateral excitation and inhibition, provides the basis for this difficult but all-important information processing capability. This capability emerges in the presence of noise automatically through effects of STDP on connections between pyramidal cells in Winner-Take-All circuits with lateral excitation. In fact, one can show that these motifs endow cortical microcircuits with functional properties of a hidden Markov model, a generic model for solving such tasks through probabilistic inference. Whereas in engineering applications this model is adapted to specific tasks through offline learning, we show here that a major portion of the functionality of hidden Markov models arises already from online applications of STDP, without any supervision or rewards. We demonstrate the emergent computing capabilities of the model through several computer simulations. The full power of hidden Markov model learning can be attained through reward-gated STDP. This is due to the fact that these mechanisms enable a rejection sampling approximation to theoretically optimal learning. We investigate the possible performance gain that can be achieved with this more accurate learning method for an artificial grammar task. PMID:24675787

Kappel, David; Nessler, Bernhard; Maass, Wolfgang

2014-03-01

335

Modeling Of Permanent Magnet Motor Drives

NASA Astrophysics Data System (ADS)

Recent research has indicated that the permanent magnet motor drives which include the permanent magnet synchronous motor (PMSM) and the brushless DC motor (BDCM) could become serious competitors to the induction motor for servo applications. The PMSM has a sinusoidal back emf and requires sinusoidal stator currents to produce constant torque while the BDCM has a trapezoidal back emf and requires rectangular stator currents to produce constant torque. The PMSM is very similar to the wound rotor synchronous machine except that the PMSM that is used for servo applications tend not to have any damper windings and excitation is provided by a permanent magnet instead of a field winding. Hence the d,q model of the PMSM can be derived from the well known model of the synchronous machine with the equations of the damper windings and field current dynamics removed. Because of the nonsinusoidal variation of the mutual inductances between the stator and rotor in the BDCM, it is also shown in this paper that no particular advantage exists in transforming the abc equations of the BCDM to the d,q frame. Hence the solution of the original abc equations is proposed for the BDCM.

Pillay, P.; Krishnan, R.

1987-10-01

336

NASA Astrophysics Data System (ADS)

Mapping the neuronal circuits is essential to understand brain function. Recent technological advancements have made it possible to acquire the brain atlas at single cell resolution. Digital reconstruction of the neural circuits down to this level across the whole brain would significantly facilitate brain studies. However, automatic reconstruction of the dense neural connections from microscopic image still remains a challenge. Here we developed a spherical-coordinate based variational model to reconstruct the shape of the cell body i.e. soma, as one of the procedures for this purpose. When intuitively processing the volumetric images in the spherical coordinate system, the reconstruction of somas with variational model is no longer sensitive to the interference of the complicated neuronal morphology, and could automatically and robustly achieve accurate soma shape regardless of the dense spatial distribution, and diversity in cell size, and morphology. We believe this method would speed drawing the neural circuits and boost brain studies.

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

2014-05-01

337

A spatially continuous magnetization model for Mars K. A. Whaler

A spatially continuous magnetization model for Mars K. A. Whaler School of GeoSciences, University model for Mars. The magnetized layer was assumed to be 40 km thick, an average value based on previous be used to downward continue magnetic data, and a comparison with other leveling techniques at Mars

338

Journal of Magnetism and Magnetic Materials 310 (2007) 428Â430 Underscreened Kondo lattice model Available online 3 November 2006 Abstract We have developed an underscreened Kondo lattice model model; Kondo lattice; Uranium compounds The normal Kondo-lattice model has been extensively studied

Iglesias, JosÃ© Roberto

339

Simulation of double layers in a model auroral circuit with nonlinear impedance

NASA Technical Reports Server (NTRS)

A reduced circuit description of the U-shaped potential structure of a discrete auroral arc, consisting of the flank transmission line plus parallel-electric-field region, is used to provide the boundary condition for one-dimensional simulations of the double-layer evolution. The model yields asymptotic scalings of the double-layer potential, as a function of an anomalous transport coefficient alpha and of the perpendicular length scale l(a) of the arc. The arc potential phi(DL) scales approximately linearly with alpha, and for alpha fixed phi (DL) about l(a) to the z power. Using parameters appropriate to the auroral zone acceleration region, potentials of phi (DPL) 10 kV scale to projected ionospheric dimensions of about 1 km, with power flows of the order of magnitude of substorm dissipation rates.

Smith, R. A.

1986-01-01

340

Percolation in a nanotube-polymer system and its lumped-circuit modeling

Electrical properties of composites composed of polyurethane polymer and multi-walled nanotubes are reported. Samples with different nanotube volume fractions are prepared, and an impedance spectroscopy technique in the frequency range from 10 mHz to 10 MHz is used to characterize the properties of the samples. It is observed that the resistivity of the mixture can be varied widely, from {approx}10 M{Omega}m to {approx}1 {Omega}m, just by slightly altering the volume fraction of nanotubes. A lumped-circuit model illustrated that the micro-scale morphology between nanotube-clusters influences the resistive relaxation in the composite system. The investigations show that the presented binary mixture has a potential to be utilized in conductive electrical components (flexible electrodes), electromagnetic shielding, and electrostatic and field grading materials for electronic and high voltage insulation technologies.

Tuncer, Enis [ORNL; Vaia, Richard A [ORNL; Arlen, Michael Jeffrey [ORNL

2010-01-01

341

Feedback and sensitivity in an electrical circuit: An analog for climate models

Earth's climate sensitivity is often interpreted in terms of feedbacks that can alter the sensitivity from that of a no-feedback Stefan-Boltzmann radiator, with the feedback concept and algebra introduced by analogy to the use of this concept in the electronics literature. This analogy is quite valuable in interpreting the sensitivity of the climate system, but usage of this algebra and terminology in the climate literature is often inconsistent, with resultant potential for confusion and loss of physical insight. Here a simple and readily understood electrical resistance circuit is examined in terms of feedback theory to introduce and define the terminology that is used to quantify feedbacks. This formalism is applied to the feedbacks in an energy-balance model of Earth's climate and used to interpret the magnitude of feedback in the climate system that corresponds to present estimates of Earth's climate sensitivity.

Schwartz, S.E.

2010-07-27

342

Modeling and short circuit detection of 18650 Li-ion cells under mechanical abuse conditions

NASA Astrophysics Data System (ADS)

In this research a simple, yet accurate model of a single cell, needed for safety assessment of batteries under mechanical abuse conditions, was developed. Extensive testing was performed on a 18650 lithium ion cell, including indentation by a hemispherical punch, lateral indentation by a cylindrical rod, compression between two flat plates, and three-point bending. The batteries were tested in an environmental chamber at a 10% SOC. A finite element model was developed, composed of shell elements representing outside casing, and solid elements for the active material with a binder lumped together with the current collectors and the separator. The jelly roll is modeled as a homogenized and isotropic material. The homogenous model assumes different properties in tension and compression, but does not account for the effect of structural anisotropy caused by the layered nature of the jelly roll. Very good correlation was obtained between LS Dyna numerical simulation and test results in terms of load-displacement relations, deformed shape of the battery, and initiation and propagation of a crack in the shell casing. The FE model was also capable of predicting the onset of short circuit of the cell.

Sahraei, Elham; Campbell, John; Wierzbicki, Tomasz

2012-12-01

343

NASA Astrophysics Data System (ADS)

In this work, we show how to use the model for assessment of CMOS technology and roadmaps (MASTAR) in order to generate ready-to-use simple pre-simulation program with integrated circuit emphasis (pre-SPICE) data. Calibration of MASTAR on silicon data is shown, as well as prediction of device behaviour due to architectural changes. The generated pre-SPICE parameters are applied to small circuit simulations such as a 10-bit adder, and we show the impact of variability on static random access memory (SRAM) functionality.

Boeuf, Frederic; Sellier, Manuel; Payet, Fabrice; Borot, Bertrand; Skotnicki, Thomas

2008-05-01

344

Magnetic microspheres and tissue model studies for therapeutic applications

NASA Technical Reports Server (NTRS)

The use of magnetic fluids and magnetic particles in combinatorial hyperthermia therapy for cancer treatment is reviewed. The investigation approach adopted for producing thermoregulating particles and tissue model studies for studying particle retention and heating characteristics is discussed.

Ramachandran, Narayanan; Mazuruk, Konstantin

2004-01-01

345

Modeling graphene: Magnetic, transport and optical properties

NASA Astrophysics Data System (ADS)

Graphene, with its unique linear dispersion near the Fermi energy, has attracted great attention since its successful isolation from highly oriented pyrolytic graphite in 2004. Many important properties have been identified in graphene, including a remarkably high mobility at room temperature, an unusual quantum hall effect, and an ambipolar electric field effect. It has been proposed as a candidate for many applications, such as optical modulators, spintronic devices, and solar cells. Understanding the fundamental properties of graphene is therefore important. In this dissertation, I present a study of transport, magnetism and optical properties of graphene. In the first chapter, I introduce the electronic properties of mono layer and few layer graphene. In the second chapter, I present low temperature transport measurements in few layer graphene. An electric-field induced semimetal-to-metal transition is observed based on the temperature dependence of the resistance for different applied gate voltages. At small gate voltages the resistance decreases with increasing temperature due to the increase in carrier concentration resulting from thermal excitation of electron-hole pairs, as it is characteristic of a semimetal. At large gate, voltages excitations of electron-hole pairs are suppressed, and the resistance increases with increasing temperature because of the decrease in mean free path due to electron-phonon scattering, as is characteristic of a metal. The electron and hole mobilities are almost equal, so there is approximate electron-hole symmetry. The data are analyzed according to two different theoretical models for few-layer graphene. A simple two band (STB) model, two overlapping bands with quadratic energy-versus-momentum dispersion relations, is used to explain the experimental observations. The best fitting parameter for the overlap energy is found to be 16 meV. However, at low temperatures, the STB suggests that the conductivity is gate independent in the small gate voltage regime, which is not observed in the data. By considering frustration of the electronic potential due to impurities from the substrate, a Gaussian-distribution puddle model can successfully describe the observed transport behavior in the low temperature, small gate voltage regime. In the third chapter, I investigate the effects of point and line defects in monolayer graphene within the framework of the Hubbard model, using a self-consistent mean field theory. These defects are found to induce characteristic patterns into the electronic density of states and cause non-uniform distributions of magnetic moments in the vicinity of the impurity sites. Specifically, defect induced resonances in the local density of states are observed at energies close to the Dirac points. The magnitudes of the frequencies of these resonance states are shown to decrease with the strength of the scattering potential, whereas their amplitudes decay algebraically with increasing distance from the defect. For the case of defect clusters, we observe that with increasing defect cluster size the local magnetic moments in the vicinity of the cluster center are strongly enhanced. Furthermore, non-trivial impurity induced magnetic patterns are observed in the presence of line defects: zigzag line defects are found to introduce stronger-amplitude magnetic patterns than armchair line defects. When the scattering strength of these topological defects is increased, the induced patterns of magnetic moments become more strongly localized. In the fourth chapter, I theoretically study the electronic properties properties in graphene dots under mechanical deformation, using both tight binding lattice model and effective Dirac model. We observed an edge state, which is tunned by an effective quantum well originating from a strain-induced gauge field. Applying a uniaxial strain along the zigzag or armchair directions enhances or dampens the edge state due to the development of edge quantum wells. When an arc bending deformation is applied, the inner and outer edges of graphene dot

Chang, Yi Chen

346

Magnetic impurities in the honeycomb Kitaev model.

We study the effect of coupling magnetic impurities to the honeycomb lattice spin-1/2 Kitaev model in its spin-liquid phase. We show that a spin-S impurity coupled to the Kitaev model is associated with an unusual Kondo effect with an intermediate coupling unstable fixed point Kc?J/S separating topologically distinct sectors of the Kitaev model. We also show that the massless spinons in the spin-liquid mediate an interaction of the form Si?2Sj?2/Rij3 between distant impurities unlike the usual dipolar RKKY interaction Si?Sj?/Rij3 noted in various 2D impurity problems with a pseudogapped density of states of the spin bath. Furthermore, this long-range interaction is possible only if the impurities (a) couple to more than one neighboring spin on the host lattice and (b) the impurity spin S?1/2. PMID:20867601

Dhochak, Kusum; Shankar, R; Tripathi, V

2010-09-10

347

A mathematical model was developed to quantitatively describe the intermetallic compound (IMC) layer growth that takes place between a Sn-based solder and a noble metal thick film conductor material used in hybrid microcircuit (HMC) assemblies. The model combined the reaction kinetics of the solder/substrate interaction, as determined from ancillary isothermal aging experiments, with a 2-D finite element mesh that took account of the porous morphology of the thick film coating. The effect of the porous morphology on the IMC layer growth when compared to the traditional 1-D computations was significant. The previous 1-D calculations under-predicted the nominal IMC layer thickness relative to the 2-D case. The 2-D model showed greater substrate consumption by IMC growth and lesser solder consumption that was determined with the 1-D computation. The new 2-D model allows the design engineer to better predict circuit aging and hence, the reliability of HMC hardware that is placed in the field.

Vianco, P.T.; Erickson, K.L.; Hopkins, P.L.

1997-12-31

348

Planetary magnetic fields: Observations and models

NASA Astrophysics Data System (ADS)

The state of knowledge and understanding of planetary magnetic fields is reviewed. All of the planets, with the possible exception of Venus, have had active dynamos at some time in their evolution. The properties and characteristics of the dynamos are as diverse as the planets themselves. Even within the subclasses of terrestrial and giant planets, the contrasting compositions, sizes, and internal pressures and temperatures of the planets result in strikingly different dynamos. As an example, the dynamos in Mercury and Ganymede are likely driven by compositional buoyancy distributions different from that in the Earth's core. Dynamo models operate far from the parameter regimes appropriate to the real planets, yet provide insight into the dynamics of their interiors. While Boussinesq models are generally adequate for simulating terrestrial planet dynamos, anelastic models that also account for large density and electrical conductivity variations are needed to simulate the dynamos in giant planets. Future spacecraft missions to planets with active dynamos are needed to learn about the character and temporal variability of the planetary magnetic fields.

Schubert, G.; Soderlund, K. M.

2011-08-01

349

NSDL National Science Digital Library

In this activity about electricity, learners identify closed and open circuits. First, learners examine and label diagrams of open and closed circuits. Then, learners build each of the circuits shown in the diagrams using electrical supplies. Throughout the activity, learners predict and then test if the light bulbs will turn on based on the circuit type.

University of Wisconsin Extension

2002-01-01

350

NSDL National Science Digital Library

Circuit Builder simulates AC and DC circuits. Circuit Builder can be used in interactive mode (see above) or it can be scripted using JavaScript (see the demo pages). In order for scripting to work, Circuit Builder requires a Java 1.1 capable browser with JavaScript to Java scripting capability.

Van Hoecke, Toon

351

1 SPICE Macro-Modeling for the Compact Simulation of Single Electron Circuits Y. S. Yu, H. S. Lee-701, Korea Abstract This paper presents SPICE macro-modeling techniques for the compact simulation of single would be required such as in the case of conventional circuit simulators (SPICE). Recently, it has been

Hwang, Sung Woo

352

NASA Astrophysics Data System (ADS)

In this paper, we survey two kinds of mathematics-based battery models intended for use in hybrid and electric vehicle simulation. The first is circuit-based, which is founded upon the electrical behaviour of the battery, and abstracts away the electrochemistry into equivalent electrical components. The second is chemistry-based, which is founded upon the electrochemical equations of the battery chemistry.

Seaman, Aden; Dao, Thanh-Son; McPhee, John

2014-06-01

353

circuit model. Circuit parameters in Figure 5 include pull-up and pull-down resistances R1,up, R1,down, R2,up and R2,down of B1 and B2, interconnect parasitic resistances R1, R2, R3 and R4, bridge resistance Rb, capacitances C1 and C2 that includes... fault at Out1 An increased delay at Out1 Rb Figure 7. The relationship between Rb and Out1. Similarly for Out2, the BTR is ))( ,11 4 , , down t up Vdd RRVVdd RR +? ? += . (2.2) The case when In1 is high and In2 is low is symmetric...

Lu, Xiang

2006-04-12

354

NSDL National Science Digital Library

Squishy Circuits was developed to teach elementary school children about circuit electricity by letting them build circuits from a PlayDoh-like substance. There are two simple recipes for making the dough: one is conductive and one is insulating. At the simplest level, kids construct a series circuit consisting of one LED, a battery pack, conductive dough, and insulating dough. Learning progresses through parallel circuit construction, motor circuits, buzzer circuits, advanced RGB-LED circuits, and "squishy" animals. All materials are easily acquired, or a kit can be purchased from the website for about $20. Editor's Note: The Squishy Circuits project team has created high-quality videos to accompany the activities. They cover set-up & preparation, LED calculations, tips for teaching the concepts to small children, and directions for building the more advanced circuits.

Thomas, Annmarie

2011-11-25

355

NASA Technical Reports Server (NTRS)

A driver circuit which has low power requirements, a relatively small number of components and provides flexibility in output voltage setting. The driver circuit comprises, essentially, two portions which are selectively activated by the application of input signals. The output signal is determined by which of the two circuit portions is activated. While each of the two circuit portions operates in a manner similar to silicon controlled rectifiers (SCR), the circuit portions are on only when an input signal is supplied thereto.

Matsumoto, Raymond T. (Inventor); Higashi, Stanley T. (Inventor)

1976-01-01

356

NSDL National Science Digital Library

Students build a saltwater circuit, which is an electrical circuit that uses saltwater as part of the circuit. Students investigate the conductivity of saltwater, and develop an understanding of how the amount of salt in a solution impacts how much electrical current flows through the circuit. They learn about one real-world application of a saltwater circuit â as a desalination plant tool to test for the removal of salt from ocean water.

Integrated Teaching And Learning Program

357

Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

NASA Technical Reports Server (NTRS)

The evolution and long-time stability of a double layer in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double-layer potential structure. A simple model is presented in which this current re-distribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double-layer potential. The flank charging may be represented as that of a nonlinear transmission. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a 1-d simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

Smith, Robert A.

1987-01-01

358

Anomalous transport in discrete arcs and simulation of double layers in a model auroral circuit

NASA Technical Reports Server (NTRS)

The evolution and long-time stability of a double layer (DL) in a discrete auroral arc requires that the parallel current in the arc, which may be considered uniform at the source, be diverted within the arc to charge the flanks of the U-shaped double layer potential structure. A simple model is presented in which this current redistribution is effected by anomalous transport based on electrostatic lower hybrid waves driven by the flank structure itself. This process provides the limiting constraint on the double layer potential. The flank charging may be represented as that of a nonlinear transmission line. A simplified model circuit, in which the transmission line is represented by a nonlinear impedance in parallel with a variable resistor, is incorporated in a one-dimensional simulation model to give the current density at the DL boundaries. Results are presented for the scaling of the DL potential as a function of the width of the arc and the saturation efficiency of the lower hybrid instability mechanism.

Smith, Robert A.

1987-01-01

359

Quasilinear transport modelling at low magnetic shear

Accurate and computationally inexpensive transport models are vital for routine and robust predictions of tokamak turbulent transport. To this end, the QuaLiKiz [Bourdelle et al., Phys. Plasmas 14, 112501 (2007)] quasilinear gyrokinetic transport model has been recently developed. QuaLiKiz flux predictions have been validated by non-linear simulations over a wide range in parameter space. However, a discrepancy is found at low magnetic shear, where the quasilinear fluxes are significantly larger than the non-linear predictions. This discrepancy is found to stem from two distinct sources: the turbulence correlation length in the mixing length rule and an increase in the ratio between the quasilinear and non-linear transport weights, correlated with increased non-linear frequency broadening. Significantly closer agreement between the quasilinear and non-linear predictions is achieved through the development of an improved mixing length rule, whose assumptions are validated by non-linear simulations.

Citrin, J.; Hogeweij, G. M. D. [FOM Institute DIFFER-Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Nieuwegein (Netherlands); Bourdelle, C.; Cottier, P. [CEA, IRFM, F-13108 Saint Paul Lez Durance (France); Escande, D. F. [UMR 6633 CNRS-Universite de Provence, Marseille (France); Guercan, Oe. D. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex (France); Hatch, D. R.; Jenko, F.; Pueschel, M. J. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-85748 Garching (Germany)

2012-06-15

360

Magnetic Fluid Model Induced by Peristaltic Waves

NASA Astrophysics Data System (ADS)

To understand theoretically the flow properties of physiological fluids, we have considered as a model of the peristaltic motion in a tube, with a sinusoidal wave of small amplitude traveling down its wall. The mathematical model considers a viscous incompressible fluid under the effect of a transverse magnetic field. The wavelength of the traveling wave is taken to be large. The expressions for the stream function, the axial velocity, the pressure gradient and the pressure rise per wavelength have been obtained. The results obtained in the analysis have been evaluated analytically and discussed with the help of graphs. The significance of the Hartmann number has been pointed out by comparing the results with hydrodynamic case. Further, the analogy between the magnetohydrodynamic fluid and hydrodynamic fluid in a porous medium has also been considered.

Siddiqui, A. M.; Hayat, T.; Khan, Masood

2004-08-01

361

Models for Mars' Magnetic Scalar Potential

Mars Global Surveyor MAG\\/ER measured strongly magnetized crust, despite Mars' weak field at present, the intensity reaches about 10 times that of Earth's magnetic lineations. We analyze the magnetic lineations in an octant centered at 40° S, 180° W +\\/-40° , concentrated in the more heavily cratered Southern hemisphere. Data from the mapping phase of Mars Global Surveyor, MAG\\/ER magnetic

D. M. Jurdy; M. Stefanick

2003-01-01

362

A new ferromagnetic hysteresis model for soft magnetic composite materials

NASA Astrophysics Data System (ADS)

A new ferromagnetic hysteresis model for soft magnetic composite materials based on their specific properties is presented. The model relies on definition of new anhysteretic magnetization based on the Cauchy-Lorentz distribution describing the maximum energy state of magnetic moments in material. Specific properties of soft magnetic composite materials (SMC) such as the presence of the bonding material, different sizes and shapes of the Fe particles, level of homogeneity of the Fe particles at the end of the SMC product treatment, and achieved overall material density during compression, are incorporated in both the anhysteretic differential magnetization susceptibility and the irreversible differential magnetization susceptibility. Together they form the total differential magnetization susceptibility that defines the new ferromagnetic hysteresis model. Genetic algorithms are used to determine the optimal values of the proposed model parameters. The simulated results show good agreement with the measured results.

Zidari?, Bogomir; Miljavec, Damijan

2011-01-01

363

Development of models of magnetic films on a liquid substrate

The authors present new results of simple experiments conducted with films of magnetic surface-active materials (SAM) deposited on the surface of water. They use magnetic liquid with the following composition: kerosene, oleic acid, magnetite. They conclude that in constructing models of magnetic films it is necessary to take account of their mass exchange with volummetric masses.

Taktarov, N.G.

1985-07-01

364

Development of models of magnetic films on a liquid substrate

The authors present new results of simple experiments conducted with films of magnetic surface-active materials (SAM) deposited on the surface of water. They use magnetic liquid with the following composition: kerosene, oleic acid, magnetite. They conclude that in constructing models of magnetic films it is necessary to take account of their mass exchange with volummetric masses.

Taktarov

1985-01-01

365

A Reptation Model for Magnetic Materials Thomas R. Braun

in a phenomenological manner as a combination of history- dependent and history-independent Preisach models [8]. Here weA/m) Magnetization(kA/m) Figure 1: Magnetic field versus magnetization for a steel rod. Both minor loops were

366

The state-of-the-art theoretical evaluation and rationalization of the magnetic interactions (J(AB)) in molecule-based magnets is discussed in this critical review, focusing first on isolated radical···radical pair interactions and afterwards on how these interactions cooperate in the solid phase. Concerning isolated radical pairwise magnetic interactions, an initial analysis is done on qualitative grounds, concentrating also on the validity of the most commonly used models to predict their size and angularity (namely, McConnell-I and McConnell-II models, overlap of magnetic orbitals,…). The failure of these models, caused by their oversimplified description of the magnetic interactions, prompted the introduction of quantitative approaches, whose basic principles and relative quality are also evaluated. Concerning the computation of magnetic interactions in solids, we resort to a sum of pairwise magnetic interactions within the Heisenberg Hamiltonian framework, and follow the First-principles Bottom-Up procedure, which allows the accurate study of the magnetic properties of any molecule-based magnet in an unbiased way. The basic principles of this approach are outlined, applied in detail to a model system, and finally demonstrated to properly describe the magnetic properties of molecule-based systems that show a variety of magnetic topologies, which range from 1D to 3D (152 references). PMID:21321725

Novoa, J J; Deumal, M; Jornet-Somoza, J

2011-06-01

367

A nonlinear GaAs FET model for use in the design of output circuits for power amplifiers

A nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, inducing drain-gate avalanche current data. The harmonic-balance technique is used to develop the FET load-pull characteristics in an amplifier configuration under large-signal operation. Computed and experimental load-pull results show good agreement.

W. R. Curtice; M. Ettenberg

1985-01-01

368

Correlations between the external discharge parameters (the driving frequency ? and the chamber dimension R) and plasma characteristics (the skin depth ? and the electron-neutral collision frequency ?{sub m}) are studied using the transformer circuit model [R. B. Piejak et al., Plasma Sources Sci. Technol. 1, 179 (1992)] when the absorbed power is maximized in an inductively coupled plasma. From the analysis of the transformer circuit model, the maximum power transfer conditions, which depend on the external discharge parameters and the internal plasma characteristics, were obtained. It was found that a maximum power transfer occurs when ??0.38R for the discharge condition at which ?{sub m}/??1, while it occurs when ???(2)?(?/?{sub m})R for the discharge condition at which ?{sub m}/??1. The results of this circuit analysis are consistent with the stable last inductive mode region of an inductive-to-capacitive mode transition [Lee and Chung, Phys. Plasmas 13, 063510 (2006)], which was theoretically derived from Maxwell's equations. Our results were also in agreement with the experimental results. From this work, we demonstrate that a simple circuit analysis can be applied to explain complex physical phenomena to a certain extent.

Kim, Young-Do; Lee, Hyo-Chang; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)] [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2013-09-15

369

Acetylcholine regulates memory encoding and retrieval by inducing the hippocampus to switch between pattern separation and pattern completion modes. However, both processes can introduce significant variations in the level of network activity and potentially cause a seizure-like spread of excitation. Thus, mechanisms that keep network excitation within certain bounds are necessary to prevent such instability. We developed a biologically realistic computational model of the hippocampus to investigate potential intrinsic mechanisms that might stabilize the network dynamics during encoding and retrieval. The model was developed by matching experimental data, including neuronal behavior, synaptic current dynamics, network spatial connectivity patterns, and short-term synaptic plasticity. Furthermore, it was constrained to perform pattern completion and separation under the effects of acetylcholine. The model was then used to investigate the role of short-term synaptic depression at the recurrent synapses in CA3, and inhibition by basket cell (BC) interneurons and oriens lacunosum-moleculare (OLM) interneurons in stabilizing these processes. Results showed that when CA3 was considered in isolation, inhibition solely by BCs was not sufficient to control instability. However, both inhibition by OLM cells and short-term depression at the recurrent CA3 connections stabilized the network activity. In the larger network including the dentate gyrus, the model suggested that OLM inhibition could control the network during high cholinergic levels while depressing synapses at the recurrent CA3 connections were important during low cholinergic states. Our results demonstrate that short-term plasticity is a critical property of the network that enhances its robustness. Furthermore, simulations suggested that the low and high cholinergic states can each produce runaway excitation through unique mechanisms and different pathologies. Future studies aimed at elucidating the circuit mechanisms of epilepsy could benefit from considering the two modulatory states separately. PMID:24978936

Hummos, Ali; Franklin, Charles C; Nair, Satish S

2014-12-01

370

circuits containing 2 X 2 X 2, 4 X 4 X 4, and 6 X 6 X 6 cubes. For the last two cases, the study reported here is limited to the vicinity of one major peak of T(c)(H) only, in order to limit the total computing time. However, by going up to 6 X 6 X 6 cubes...

YI, YM; Hu, Chia-Ren.

1992-01-01

371

to the concept of parametric yield, also known as circuit-limited yield. With technology scaling, circuits. Index Terms--Correlations, die-to-die variations, generic crit- ical path, parametric yield, principal are more exposed to the adverse effects of process tolerances, and parametric yield becomes a crucial

Najm, Farid N.

372

Double-Strength CAFFEINE: Fast Template-Free Symbolic Modeling of Analog Circuits via Implicit-MICAS Kasteelpark Arenberg 10 B-3001 Leuven, Belgium Abstract CAFFEINE, introduced previously, automatically of analog circuits, CAFFEINE was shown to have the best predictive ability from among 10 regression

Fernandez, Thomas

373

An original, fully analytical, spectral domain decomposition approach is presented for the time-dependent thermal modeling of complex nonlinear (3-D) electronic systems, from metallized power FETs and MMICs, through MCMs, up to circuit board level. This solution method offers a powerful alternative to conventional numerical thermal simulation techniques, and is constructed to be compatible with explicitly coupled electrothermal device and circuit

William Batty; Carlos E. Christoffersen; Andreas J. Panks; Stéphane David; Christopher M. Snowden; Michael B. Steer

2001-01-01

374

The conventional charged device model (CDM) test methods for large-scale integrated (LSI) circuits have not prescribed the device capacitance; furthermore, the CDM sensitivity has been represented by the withstand voltage. Also, a method for measuring the voltage of small objects such as LSI circuits has not been established. For these reasons, the failure voltages obtained with every kind of tester

K. Suzuki; T. Muranoi; R. Sugita; M. Takeuchi; T. Hariu

1998-01-01

375

NASA Astrophysics Data System (ADS)

We present a new high-resolution model of the Earth's global atmospheric electric circuit (GEC) represented by an equivalent electrical network. Contributions of clouds to the total resistance of the atmosphere and as current generators are treated more realistically than in previous GEC models. The model of cloud current generators is constructed on the basis of the ISCCP cloud data and the OTD/LIS lightning flash rates and TRMM rainfall data. The current generated and the electric resistance can be estimated with a spatial resolution of several degrees in latitude and longitude and 3 hour time resolution. The resistance of the atmosphere is calculated using an atmospheric conductivity model which is spatially dependent and sensitive to the level of solar activity. An equivalent circuit is constructed assuming the ionosphere and ground are ideal conductors. The circuit solution provides diurnal variations of the ionospheric potential and the GEC global current at the 3 hour time resolution as well as the global distributions and diurnal variations of the air-Earth current density and electric field. The model confirms that the global atmospheric electric activity peaks daily at ˜21 UT. The diurnal variation of the ionospheric potential and the global current have a maximum at 12 and 21-24 UT in July and at 9 and 21 UT in December, and a global minimum at 3-6 UT independent of season. About 80% of the current is generated by thunderstorm convective clouds and 20% by mid-level rain clouds.

Odzimek, A.; Lester, M.; Kubicki, M.

2010-09-01

376

NASA Astrophysics Data System (ADS)

The purpose of this PhD work has been to investigate, model, test, develop and provide hardening techniques and guidelines for the mitigation of single event transients (SETs) in analog mixed-signal (AMS) delay locked loops (DLLs) for radiation-hardened applications. Delay-locked-loops (DLLs) are circuit substructures that are present in complex ASIC and system-on-a-chip designs. These circuits are widely used in on-chip clock distribution systems to reduce clock skew, to reduce jitter noise, and to recover clock signals at regional points within a global clock distribution system. DLLs are critical to the performance of many clock distribution systems, and in turn, the overall performance of the associated integrated system; as such, complex systems often employ multiple DLLs for clock deskew and distribution tasks. In radiation environments such as on-orbit, these critical circuits represent at-risk points of malfunction for large sections of integrated circuits due to vulnerabilities to radiation-generated transients (i.e. single event transients) that fan out across the system. The analysis of single event effects in analog DLLs has shown that each DLL sub-circuit primitive is vulnerable to single event transients. However, we have identified the voltage controlled delay line (VCDL) sub-circuit as the most sensitive to radiation-induced single event effects generating missing clock pulses that increase with the operating frequency of the circuit. This vulnerability increases with multiple instantiation of DLLs as clock distribution nodes throughout an integrated system on a chip. To our knowledge, no complete work in the rad-hard community regarding the hardening of mixed-signal DLLs against single event effects (missing pulses) has been developed. Most of the work present in the literature applies the "brute force" and well-established digital technique of triple modular redundancy (TMR) to the digital subcomponents. We have developed two novel design techniques for the mitigation of DLL missing pulses that are fully implementable in modern CMOS technologies. These techniques offer to the community the choice of hardening using a restoring current technique in the VCDL sub-circuit to inhibit the creation of missing pulse errors, or using a combinational logic error monitoring technique to correct missing pulses after they occur in real time. We have implemented both of these techniques with minimal area and power penalties when compared to TMR. In addition, these hardening techniques have been extrapolated to other clock circuits, such as digital PLLs. The first hardening technique uses a hardened complementary differential pair VCDL to increase the critical charge (Qcrit) necessary for single event transient generation and thus mitigate missing pulses at the source. Our implementation of this technique at 180 nm, 90 nm and 40 nm required less than a 2% area penalty over a non-hardened design. To experimentally validate this technique, hardened VCDLs were designed and fabricated in 180-nm IBM and 40-nm UMC technologies, then tested at the Naval Research Lab in Washington D.C. The second hardening technique, based on combinational logic pulse monitoring, uses an error correction circuit to mitigate the missing pulses as they occur. This ECC technique is implemented via a "peeled" VCDL (i.e. each transistor is split in area but doubled in multiplicity). We have shown the effectiveness of this technique by implementing it in a Xilinx Virtex 5 FPGA. Furthermore, this new ECC technique is independent of technology scaling -- a highly valuable attribute for sub-50 nm design applications. In addition to the formulation, simulation, prototyping, fabrication, and testing of these new hardening solutions, we developed a unique single event analytical model to guide future hardened DLL designs at advanced technology nodes. The model was furthermore generalized to PLL and DLLs. These analytical models were then used to provide a set of equations to the designer for important insight into hardening choices an

Maillard, Pierre

377

Thermally assisted spin transfer torque [TAS + STT] is a new switching approach for magnetic tunnel junction [MTJ] nanopillars that represents the best trade-off between data reliability, power efficiency and density. In this paper, we present a compact model for MTJ switched by this approach, which integrates a number of physical models such as temperature evaluation and STT dynamic switching models. Many experimental parameters are included directly to improve the simulation accuracy. It is programmed in the Verilog-A language and compatible with the standard IC CAD tools, providing an easy parameter configuration interface and allowing high-speed co-simulation of hybrid MTJ/CMOS circuits. PMID:21711868

2011-01-01

378

Vibrational and Ghost-Vibrational Resonances in A Modified Chua's Circuit Model Equation

The role of the number of breakpoints $N$ in the sawtooth form of the characteristic function in the modified Chua's circuit model equation on vibrational and ghost-vibrational resonances is investigated in this paper. To observe vibrational resonance the system should be driven by two periodic forces of frequencies $\\omega$ and $\\Omega$, with $\\Omega\\gg\\omega$. Resonance occurs at the frequency $\\omega$ when the amplitude of the high-frequency force is varied. When the system is subjected to an input signal containing multi-frequencies which are higher-order of a certain (missing) fundamental frequency, then a resonance at the missing fundamental frequency is induced by the high-frequency input signal and is called ghost-vibrational resonance. In both types of resonances, the number of resonances is $N$ and hysteresis occurs in each resonance region. There are some similarities and differences in these two resonance phenomena. We report in detail the influence of the role of number of breakpoints $N$ on the features of vibrational and ghost-vibrational resonances.

K. Abirami; S. Rajasekar; M. A. F. Sanjuan

2014-06-26

379

Speckle measurements of density and temperature profiles in a model gas circuit breaker

NASA Astrophysics Data System (ADS)

Speckle imaging was used to measure the density and temperature distribution in the arc zone of a model high voltage circuit breaker during the high current phase and under conditions simulating those present during current-zero crossings (current-zero-like arc); the arc was stabilized by a transonic, axial flow of synthetic air. A single probe beam was used; thus, accurate reconstruction was only possible for axially symmetric gas flows and arc channels. The displacement of speckles with respect to a reference image was converted to a line-of-sight integrated deflection angle, which was in turn converted into an axially symmetric refractive index distribution using a multistep process that made use of the inverse Radon transform. The Gladstone–Dale relation, which gives the index of refraction as a function of density, was extended to high temperatures by taking into account dissociation and ionization processes. The temperature and density were determined uniquely by assuming that the pressure distribution in the case of cold gas flow (in the absence of an arc) is not modified significantly by the arc. The electric conductivity distribution was calculated from the temperature profile and compared to measurements of the arc voltage and to previous results published in the literature for similar experimental conditions.

Stoller, P. C.; Panousis, E.; Carstensen, J.; Doiron, C. B.; Färber, R.

2015-01-01

380

Vibrational and Ghost-Vibrational Resonances in a Modified Chua's Circuit Model Equation

NASA Astrophysics Data System (ADS)

The role of the number of breakpoints $N$ in the sawtooth form of the characteristic function in the modified Chua's circuit model equation on vibrational and ghost-vibrational resonances is investigated in this paper. To observe vibrational resonance the system should be driven by two periodic forces of frequencies $\\omega$ and $\\Omega$, with $\\Omega\\gg\\omega$. Resonance occurs at the frequency $\\omega$ when the amplitude of the high-frequency force is varied. When the system is subjected to an input signal containing multi-frequencies which are higher-order of a certain (missing) fundamental frequency, then a resonance at the missing fundamental frequency is induced by the high-frequency input signal and is called ghost-vibrational resonance. In both types of resonances, the number of resonances is $N$ and hysteresis occurs in each resonance region. There are some similarities and differences in these two resonance phenomena. We report in detail the influence of the role of number of breakpoints $N$ on the features of vibrational and ghost-vibrational resonances.

Abirami, K.; Rajasekar, S.; Sanjuan, M. A. F.

2014-11-01

381

Fast Algorithms for High Frequency Interconnect Modeling in VLSI Circuits and Packages

of techniques are available. However, for high frequency circuits and packages, parasitic inductance and impedance extraction still poses a tremendous challenge. Existing algorithms, such as FastImp and FastHenry developed by MIT, are slow and inherently unable...

Yi, Yang

2011-02-22

382

Improved model generation and property specification for analog/mixed-signal circuits.

??This document describes an improved method of formal verification of complex analog/mixed-signal (AMS) circuits. Currently, in our LEMA tool, verification properties are encoded using labeled… (more)

Kulkarni, Dhanashree R.

2013-01-01

383

Magnetic forward models of the Cement oil field, Oklahoma, were generated to assess the possibility that ferrimagnetic pyrrhotite related to hydrocarbon seepage in the upper 1 km of Permian strata contributes to aeromagnetic anomalies at Cement. Six bodies having different magnetizations were constructed for the magnetic models. Total magnetizations of the bodies of highest pyrrhotite content range from about 3 ?? 10-3 to 56 ?? 10-3 A/m in the present field direction and yield magnetic anomalies (at 120 m altitude) having amplitudes of less than 1 nT to ~6 to 7 nT, respectively. Numerous assumptions were made in the generation of the models, but nevertheless, the results suggest that pyrrhotite, formed via hydrocarbon reactions and within a range of concentrations estimated at Cement, is capable of causing magnetic anomalies. -from Authors

Reynolds, R.L.; Webring, M.; Grauch, V.J.S.; Tuttle, M.

1990-01-01

384

The Whitney-elements time-domain (WETD) method is a very powerful full-wave EM field solver in the time domain. The WETD method is here applied to solve a coupled problem of EM fields and circuits, which are characterized by lumped elements, distributed elements and independent sources. The method consists in the variation of the finite element functional to include circuit elements in

M. Feliziani; F. Maradei

1999-01-01

385

Modeling multilayered PCB power-bus designs using an MPIE based circuit extraction technique

A circuit extraction tool (CEMPIE) has been developed based on the mixed-potential integral equation (MPIE) using a quasi-static approximation. A power-bus in a multi-layered PCB consisting of a pair of dedicated ground and power planes is studied using this tool. The distributed behavior of a power-bus is represented by a collection of passive circuit elements, which is valid up to

Hao Shi; Jun Fan; James L. Drewniak; Todd H. Hubing; Thomas P. Van Doren

1998-01-01

386

A comprehensive study of lightning protection of over- head distribution circuits has just been completed by a Task Force consisting of eight utility companies and the General Electric Company. Most overhead circuit configurations in use today-or contemplated for use in the future-were studied. This included system voltages from 4-34.5 kV. The use of an overhead ground wire, arrester on the

1969-01-01

387

A Model to Explain the Mars Crustal Magnetic Lineations

Using both, the crustal magnetic lineations map of Mars published by the Mars Global Surveyor (MGS) MAG\\/ER experiment and the tectonic-structural features associated to the Tharsis uplift and mapped by ourselves, we have been able to generate a 2-D model of the crustal magnetization. Previous models assume uniformly magnetized strips whose dimensions are 200 km wide, 2000 km long and

A. H. Barosio; V. M. Velasco-Herrera

2002-01-01

388

A Model for Quantum Jumps in Magnetic Resonance Force Microscopy

We propose a simple model which describes the statistical properties of quantum jumps in a single-spin measurement using the oscillating cantilever-driven adiabatic reversals technique in magnetic resonance force microscopy. Our computer simulations based on this model predict the average time interval between two consecutive quantum jumps and the correlation time to be proportional to the characteristic time of the magnetic noise and inversely proportional to the square of the magnetic noise amplitude.

G. P. Berman; F. Borgonovi; V. I. Tsifrinovich

2004-02-09

389

A Model for Quantum Jumps in Magnetic Resonance Force Microscopy

We propose a simple model which describes the statistical properties of quantum jumps in a single-spin measurement using the oscillating cantilever-driven adiabatic reversals technique in magnetic resonance force microscopy. Our computer simulations based on this model predict the average time interval between two consecutive quantum jumps and the correlation time to be proportional to the characteristic time of the magnetic noise and inversely proportional to the square of the magnetic noise amplitude.

Berman, G P; Tsifrinovich, V I

2004-01-01

390

Modeling the magnetic disturbance of pulsatile blood flow in a static magnetic field.

Non-invasive continuous monitoring of blood flow may be particularly valuable for early detection of different anomalies such as hypovolemia and internal bleeding. Recent studies have demonstrated the potential clinical benefits of photo-plethysmography in detecting hypovolemia before the onset of cardiovascular decompensation. The magnetic sensing method bears advantages of size, weight, and cost along with less stringent body placement rules. In this work, a detailed three-dimensional mathematical model for the acquisition of the ventricular response using the disturbance created by magnetized blood undergoing a stationary permanent magnet is presented. The proposed model accounts for the different magnetic properties of the blood such as the relaxation time and the magnetic saturation. The blood flow is simulated by means of Navier-Stocks equations with pulsatile inlet pressure. The blood is assumed to be in the deoxygenated state and has a diamagnetic properties. Moreover, a moving mesh technique is implemented in the Finite-Element model to represent the idle and the moving states of the blood which provides the capability to model the magnetized blood as a moving magnet. The simulated magnetic field at different sensor locations is found to be in good agreement with experimental observations from the literature. The presented model can provide basis for understanding the magnetic modulated blood signal as well as the practical constraints that might be encountered in the design of such devices. PMID:25570231

Atalla, Ashraf; Nagarkar, Kaustubh; Ashe, Jeff

2014-08-01

391

NASA Astrophysics Data System (ADS)

As an important step in further modeling and understanding the global electric circuit, the Community Earth System Model (CESM1) has been extended to provide a calculation of conductivity in the troposphere and stratosphere. Conductivity depends on ion mobility and ion concentration, the latter being controlled by a number of ion production and loss processes. This leads to a complex dependency of conductivity on most importantly galactic cosmic ray flux, radon emissions from the Earth's surface, aerosol number concentrations, clouds, and temperature. To cover this variety in parameters for calculating and evaluating conductivity, an Earth system model is extremely useful. Here the extension of CESM1 to calculate conductivity is described, and the results are discussed with a focus on their spatial and temporal variabilities. The results are also compared to balloon and aircraft measurements, and good agreement is found for undisturbed conditions and during a solar proton event. The conductivity model implementation is a significant improvement to previous studies because of the high-quality, high-resolution model data input. Notably, the aerosol representation provided by off-line calculations of tropospheric and stratospheric aerosol using the Community Aerosol and Radiation Model for Atmospheres as part of CESM1(WACCM) (Whole Atmosphere Community Climate Model) provides a realistic computation of the impact of the background aerosol distribution for the first time. In addition to the novel high-resolution information on conductivity, it is found that an intra-annual cycle exists in the total global resistance, varying between 220 and 245 ?. The model shows that this cycle is driven equally by seasonal aerosol and cloud variations.

Baumgaertner, A. J. G.; Thayer, J. P.; Neely, R. R.; Lucas, G.

2013-08-01

392

Calculation and Analysis of magnetic gradient tensor components of global magnetic models

NASA Astrophysics Data System (ADS)

Magnetic mapping missions like SWARM and its predecessors, e.g. the CHAMP and MAGSAT programs, offer high resolution Earth's magnetic field data. These datasets are usually combined with magnetic observatory and survey data, and subject to harmonic analysis. The derived spherical harmonic coefficients enable magnetic field modelling using a potential series expansion. Recently, new instruments like the JeSSY STAR Full Tensor Magnetic Gradiometry system equipped with very high sensitive sensors can directly measure the magnetic field gradient tensor components. The full understanding of the quality of the measured data requires the extension of magnetic field models to gradient tensor components. In this study, we focus on the extension of the derivation of the magnetic field out of the potential series magnetic field gradient tensor components and apply the new theoretical framework to the International Geomagnetic Reference Field (IGRF) and the High Definition Magnetic Model (HDGM). The gradient tensor component maps for entire Earth's surface produced for the IGRF show low values and smooth variations reflecting the core and mantle contributions whereas those for the HDGM gives a novel tool to unravel crustal structure and deep-situated ore bodies. For example, the Thor Suture and the Sorgenfrei-Thornquist Zone in Europe are delineated by a strong northward gradient. Derived from Eigenvalue decomposition of the magnetic gradient tensor, the scaled magnetic moment, normalized source strength (NSS) and the bearing of the lithospheric sources are presented. The NSS serves as a tool for estimating the lithosphere-asthenosphere boundary as well as the depth of plutons and ore bodies. Furthermore changes in magnetization direction parallel to the mid-ocean ridges can be obtained from the scaled magnetic moment and the normalized source strength discriminates the boundaries between the anomalies of major continental provinces like southern Africa or the Eastern European Craton.

Schiffler, Markus; Queitsch, Matthias; Schneider, Michael; Stolz, Ronny; Krech, Wolfram; Meyer, Hans-Georg; Kukowski, Nina

2014-05-01

393

The Bosumtwi meteorite impact structure, Ghana: A magnetic model

NASA Astrophysics Data System (ADS)

A magnetic model is proposed for the Bosumtwi meteorite impact structure in Ghana, Africa. This relatively young (~1.07 Ma) structure with a diameter of ~10.5 km is exposed within early Proterozoic Birimian-Tarkwaian rocks. The central part of the structure is buried under post-impact lake sediments, and due to lack of drill cores, geophysics is the only way to reveal its internal structure. To study the structure below and beyond the lake, a high-resolution low altitude (~70 m) airborne geophysical survey across the structure was conducted, which included measurements of the total magnetic field, electromagnetic data, and gamma radiation. The magnetic data show a circumferential magnetic halo outside the lakeshore, ~12 km in diameter. The central-north part of the lake reveals a central negative magnetic anomaly with smaller positive side-anomalies N and S of it, which is typical for magnetized bodies at shallow latitudes. A few weaker negative magnetic anomalies exist in the eastern and western part of the lake. Together with the northern one they seem to encircle a central uplift. Our model shows that the magnetic anomaly of the structure is presumably produced by one or several relatively strongly remanently magnetized impact melt rock or melt-rich suevite bodies. Petrophysical measurements show a clear difference between the physical properties of pre-impact target rocks and impactites. Suevites have a higher magnetization and have low densities and high porosities compared to the target rocks. In suevites, the remanent magnetization dominates over induced magnetization (Koenigsberger ratio > 3). Preliminary palaeomagnetic results reveal that the normally magnetized remanence component in suevites was acquired during the Jaramillo normal polarity epoch. This interpretation is consistent with the modelling results that also require a normal polarity magnetization for the magnetic body beneath the lake. The reverse polarity remanence component, superimposed to the normal component, is probably a secondary remanence acquired during subsequent reverse polarity events.

Plado, J.; Pesonen, L. J.; Koeberl, C.; Elo, S.

2000-07-01

394

Dispersive shear Alfvén waves on model Tsyganenko magnetic field lines

We present a theory of low-m dispersive shear Alfvén waves (SAWs) that are excited on magnetic field lines specified by the Tsyganenko 1996 magnetic field model. Our dispersive nonlinear model is applied to field lines near the midnight meridional plane and is parameterized by averaged quantities along a field line. For inner plasma sheet ambient parameters, dispersion is dominated by

R. Rankin; V. T. Tikhonchuk

2001-01-01

395

ACCELERATION-293 Kicker Magnets for the Electron Model of

MUC-NOTE- ACCELERATION-293 Kicker Magnets for the Electron Model of an FFAG Ring for Muons Eberhard Storage Ring Design with Simple Mathematica Packages", CERN-SL/99-053 (AP) to the design of kicker magnets for extraction from an electron model of an FFAG ring for accelerating muons. For the pulsed kicker, I use

Keil, Eberhard

396

Advanced optical position sensors for magnetically suspended wind tunnel models

A major concern to aerodynamicists has been the corruption of wind tunnel test data by model support structures, such as stings or struts. A technique for magnetically suspending wind tunnel models was considered by Tournier and Laurenceau (1957) in order to overcome this problem. This technique is now implemented with the aid of a Large Magnetic Suspension and Balance System

S. Lafleur

1985-01-01

397

Parallelizing Quantum Circuits

We present a novel automated technique for parallelizing quantum circuits via forward and backward translation to measurement-based quantum computing patterns and analyze the trade off in terms of depth and space complexity. As a result we distinguish a class of polynomial depth circuits that can be parallelized to logarithmic depth while adding only polynomial many auxiliary qubits. In particular, we provide for the first time a full characterization of patterns with flow of arbitrary depth, based on the notion of influencing paths and a simple rewriting system on the angles of the measurement. Our method leads to insightful knowledge for constructing parallel circuits and as applications, we demonstrate several constant and logarithmic depth circuits. Furthermore, we prove a logarithmic separation in terms of quantum depth between the quantum circuit model and the measurement-based model.

Anne Broadbent; Elham Kashefi

2007-04-13

398

NASA Astrophysics Data System (ADS)

The redox (Reduction-Oxidation) flow battery is one of the most promising rechargeable batteries due to its ability to average loads and output of power sources. The transient characteristics are well known as the remarkable feature of the battery. Then it can also compensate for a sudden voltage drop. The dynamics are governed by the chemical reactions, fluid flow, and electrical circuit of its structure. This causes the difficulty of the analysis at transient state. This paper discusses the transient behavior of the redox flow battery based on chemical reactions. The concentration change of vanadium ions depends on the chemical reactions and the flow of electrolysis solution. The chemical reaction rate is restricted by the attached external electric circuit. In this paper, a model of the transient behavior is introduced. The validity of the derived model is examined based on experiments for a tested micro-redox flow battery system.

Li, Minghua; Hikihara, Takashi

399

Demonstrations with an "LCR" Circuit

ERIC Educational Resources Information Center

The "LCR" circuit is an important topic in the course of electricity and magnetism. Papers in this field consider mainly the forced oscillations and resonance. Our aim is to show how to demonstrate the free and self-excited oscillations in an "LCR" circuit. (Contains 4 figures.)

Kraftmakher, Yaakov

2011-01-01

400

Modelling coils system for generating homogeneous magnetic field

NASA Astrophysics Data System (ADS)

Magnetometers are used for measuring the characteristics of magnetic field and magnetic properties of the material. A changeable source of a homogeneous magnetic field is necessary for verification and calibration of magnetometers. Often the Helmholtz coil is used for generating magnetic homogeneous field, but homogeneous field area generated by Helmholtz coils is confined to a small volume in the center of the coils. The paper describes result of modeling a coils system to generate a homogeneous magnetic field with increased volume in comparison to Helmholtz coils.

Ogay, V.; Baranov, P.; Stepankova, A.

2014-10-01

401

Deflection modeling of permanent magnet spherical chains in the presence of external magnetic fields

NASA Astrophysics Data System (ADS)

This work examines the interaction of permanently magnetised spheres in the presence of external magnetic fields at the millimetre scale. Static chain formation and deflection models are described for N spheres in the presence of an external magnetic field. Analytical models are presented for the two sphere case by neglecting the effects of magnetocrystalline anisotropy while details of a numerical approach to solve a chain of N spheres are shown. The model is experimentally validated using chain deflections in 4.5 mm diameter spheres in groups of 2, 3 and 4 magnets in the presence of uniform magnetic fields, neglecting gravitational effects, with good agreement between the theoretical model and experimental results. This spherical chain structure could be used as an end effector for catheters as a deflection mechanism for magnetic guidance. The spherical point contacts result in large deflections for navigation around tight corners in endoluminal minimally invasive clinical applications.

O'Donoghue, Kilian; Cantillon-Murphy, Pádraig

2013-10-01

402

Modeling the magnetic pickup of an electric guitar

NASA Astrophysics Data System (ADS)

The magnetic pickup of an electric guitar uses electromagnetic induction to convert the motion of a ferromagnetic guitar string to an electrical signal. Although the magnetic pickup is often cited as an everyday application of Faraday's law, few sources mention the distortion that the pickup generates when converting the motion of a string to an electric signal, and fewer analyze and explain this distortion. We model the magnet and ferromagnetic wire as surfaces with magnetic charge and construct an intuitive model that accurately predicts the output of a magnetic guitar pickup. This model can be understood by undergraduate students and provides an excellent learning tool due to its straightforward mathematics and intuitive algorithm. Experiments show that it predicts the change in a magnetic field due to the presence of a ferromagnetic wire with a high degree of accuracy.

Horton, Nicholas G.; Moore, Thomas R.

2009-02-01

403

In this paper, a new approach for the development of planar metamaterial structures is developed. For this purpose, split-ring resonators (SRRs) and complementary split-ring resonators (CSRRs) coupled to planar transmission lines are investigated. The electromagnetic behavior of these elements, as well as their coupling to the host transmission line, are studied, and analytical equivalent-circuit models are proposed for the isolated

Juan Domingo Baena; J. Bonache; F. Martin; R. M. Sillero; F. Falcone; T. Lopetegi; M. A. G. Laso; J. Garcia-Garcia; I. Gil; M. F. Portillo; M. Sorolla

2005-01-01

404

NASA Astrophysics Data System (ADS)

The present study examines the breaking capability of a hybrid fault current-limiting circuit breaker (FCLCB) when a fault occurs at a distance l of 0, 1, 4 and 8km away from the terminals of the FCLCB. This hybrid FCLCB is composed of an air circuit breaker unit connected in series with a resistive or an inductive fault current limiter (FCL). In the model of the inductive FCL, a capacitance Cp is connected in parallel with the limiting coil to simulate a coil stray capacitance and a necessary additional capacitance. By means of Mayr equation, the time variation of the arc conductance in the air circuit breaker unit was estimated to find out the result of the current interruption (successful or failure interruption) for the hybrid FCLCB. The minimum limiting impedance required to allow the hybrid FCLCB to attain a successful interruption was found to be 5 and 7? for a resistive FCL unit and an inductive FCL unit with Cp=5nF, respectively. Further, in the presence of an inductive FCL unit with Cp=50 and 100nF, the limiting impedance needed to interrupt the fault current successfully for all fault locations was proved to be 3? or above. From the results of this study, it can be said that (1) the insertion of the FCL unit should be done on the basis of a coordination between the circuit breaker unit and the FCL unit and (2) connecting a circuit breaker in series with fault current limiters may enable us to use non-greenhouse gas as quenching medium for interrupting large currents.

Calixte, Evenson; Yokomizu, Yasunobu; Matsumura, Toshiro; Fujita, Hideki

405

Transient electromagnetic analysis coupled to electric circuits and motion

This paper presents implementation details of coupling circuit equations and motion with two dimensional finite clement models for transient magnetic analysis. Finite elements with incomplete shape functions are used in a novel way to handle the interface between the moving and stationary parts of the mesh. The final system of equations can then be solved using adaptive time stepping. Two

C. S. Biddlecombe; J. Simkin; A. P. Jay; J. K. Sykulski; S. Lepaul

1998-01-01

406

This paper reports the measurement and modelling of magnetic properties of SOMALOYTM 500, a soft magnetic composite (SMC) material, under different 2D vector magnetisations, such as alternating along one direction, circularly and elliptically rotating in a 2D plane. By using a 2D magnetic property tester, the B–H curves and core losses of the SMC material have been measured with different

Y. G. Guo; J. G. Zhu; J. J. Zhong

2006-01-01

407

Full circuit calculation for electromagnetic pulse transmission in a high current facility

NASA Astrophysics Data System (ADS)

We describe herein for the first time a full circuit model for electromagnetic pulse transmission in the Primary Test Stand (PTS)—the first TW class pulsed power driver in China. The PTS is designed to generate 8-10 MA current into a z -pinch load in nearly 90 ns rise time for inertial confinement fusion and other high energy density physics research. The PTS facility has four conical magnetic insulation transmission lines, in which electron current loss exists during the establishment of magnetic insulation. At the same time, equivalent resistance of switches and equivalent inductance of pinch changes with time. However, none of these models are included in a commercially developed circuit code so far. Therefore, in order to characterize the electromagnetic transmission process in the PTS, a full circuit model, in which switch resistance, magnetic insulation transmission line current loss and a time-dependent load can be taken into account, was developed. Circuit topology and an equivalent circuit model of the facility were introduced. Pulse transmission calculation of shot 0057 was demonstrated with the corresponding code FAST (full-circuit analysis and simulation tool) by setting controllable parameters the same as in the experiment. Preliminary full circuit simulation results for electromagnetic pulse transmission to the load are presented. Although divergences exist between calculated and experimentally obtained waveforms before the vacuum section, consistency with load current is satisfactory, especially at the rising edge.

Zou, Wenkang; Guo, Fan; Chen, Lin; Song, Shengyi; Wang, Meng; Xie, Weiping; Deng, Jianjun

2014-11-01

408

NASA Technical Reports Server (NTRS)

Modeling of interconnects and associated discontinuities with the recent advances high-speed digital circuits has gained a considerable interest over the last decade although the theoretical bases for analyzing these structures were well-established as early as the 1960s. Ongoing research at the present time is focused on devising methods which can be applied to more general geometries than the ones considered in earlier days and, at the same time, improving the computational efficiency and accuracy of these methods. In this thesis, numerically efficient methods to compute the transmission line parameters of a multiconductor system and the equivalent capacitances of various strip discontinuities are presented based on the quasi-static approximation. The presented techniques are applicable to conductors embedded in an arbitrary number of dielectric layers with two possible locations of ground planes at the top and bottom of the dielectric layers. The cross-sections of conductors can be arbitrary as long as they can be described with polygons. An integral equation approach in conjunction with the collocation method is used in the presented methods. A closed-form Green's function is derived based on weighted real images thus avoiding nested infinite summations in the exact Green's function; therefore, this closed-form Green's function is numerically more efficient than the exact Green's function. All elements associated with the moment matrix are computed using the closed-form formulas. Various numerical examples are considered to verify the presented methods, and a comparison of the computed results with other published results showed good agreement.

Oh, K. S.; Schutt-Aine, J.

1995-01-01

409

NASA Astrophysics Data System (ADS)

After decades of continued scaling to the beat of Moore's law, it now appears that conventional silicon based devices are approaching their physical limits. In today's deep-submicron nodes, a number of short-channel and quantum effects are emerging that affect the manufacturing process, as well as, the functionality of the microelectronic systems-on-chip. Spintronics devices that exploit both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, are promising solutions to circumvent these scaling threats. Being compatible with the CMOS technology, such devices offer a promising synergy of radiation immunity, infinite endurance, non-volatility, increased density, etc. In this paper, we present a hybrid (magnetic/CMOS) cell that is able to store and process data both electrically and magnetically. The cell is based on perpendicular spin-transfer torque magnetic tunnel junctions (STT-MTJs) and is suitable for use in magnetic random access memories and reprogrammable computing (non-volatile registers, processor cache memories, magnetic field-programmable gate arrays, etc). To demonstrate the potential our hybrid cell, we physically implemented a small hybrid memory block using 45 nm × 45 nm round MTJs for the magnetic part and 28 nm fully depleted silicon on insulator (FD-SOI) technology for the CMOS part. We also report the cells measured performances in terms of area, robustness, read/write speed and energy consumption.

Jovanovi?, B.; Brum, R. M.; Torres, L.

2014-04-01

410

After decades of continued scaling to the beat of Moore's law, it now appears that conventional silicon based devices are approaching their physical limits. In today's deep-submicron nodes, a number of short-channel and quantum effects are emerging that affect the manufacturing process, as well as, the functionality of the microelectronic systems-on-chip. Spintronics devices that exploit both the intrinsic spin of the electron and its associated magnetic moment, in addition to its fundamental electronic charge, are promising solutions to circumvent these scaling threats. Being compatible with the CMOS technology, such devices offer a promising synergy of radiation immunity, infinite endurance, non-volatility, increased density, etc. In this paper, we present a hybrid (magnetic/CMOS) cell that is able to store and process data both electrically and magnetically. The cell is based on perpendicular spin-transfer torque magnetic tunnel junctions (STT-MTJs) and is suitable for use in magnetic random access memories and reprogrammable computing (non-volatile registers, processor cache memories, magnetic field-programmable gate arrays, etc). To demonstrate the potential our hybrid cell, we physically implemented a small hybrid memory block using 45?nm × 45?nm round MTJs for the magnetic part and 28?nm fully depleted silicon on insulator (FD-SOI) technology for the CMOS part. We also report the cells measured performances in terms of area, robustness, read/write speed and energy consumption.

Jovanovi?, B., E-mail: bojan.jovanovic@lirmm.fr, E-mail: lionel.torres@lirmm.fr; Brum, R. M.; Torres, L. [LIRMM—University of Montpellier 2/UMR CNRS 5506, 161 Rue Ada, 34095 Montpellier (France)

2014-04-07

411

In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule. PMID:24960170

Talà, Adelfia; Delle Side, Domenico; Buccolieri, Giovanni; Tredici, Salvatore Maurizio; Velardi, Luciano; Paladini, Fabio; De Stefano, Mario; Nassisi, Vincenzo; Alifano, Pietro

2014-01-01

412

Magnetic and Magnetostrictive Characterization and Modeling of High Strength Steel

NASA Astrophysics Data System (ADS)

High strength steels exhibit small amounts of magnetostriction, which is a useful property for non-destructive testing amongst other things. This property cannot currently be fully utilized due to a lack of adequate measurements and models. This thesis reports measurements of these material parameters, and derives a model using these parameters to predict magnetization changes due to the application of compressive stresses and magnetic fields. The resulting Preisach model, coupled with COMSOL MultiphysicsRTM finite element modeling, accurately predicts the magnetization change seen in a separate high strength steel sample previously measured by the National Institute of Standards and Technology. Three sets of measurements on low-carbon, low-alloy high strength steel are introduced in this research. The first experiment measured magnetostriction in steel rods under uniaxial compressive stresses and magnetic fields. The second experiment consisted of magnetostriction and magnetization measurements of the same steel rods under the influence of bi-axially applied magnetic fields. The final experiment quantified the small effect that temperature has on magnetization of steels. The experiments demonstrated that the widely used approximation of stress as an "effective field" is inadequate, and that temperatures between -50 and 100 °C cause minimal changes in magnetization. Preisach model parameters for the prediction of the magnetomechanical effect were derived from the experiments. The resulting model accurately predicts experimentally derived major and minor loops for a high strength steel sample, including the bulging and coincident points attributed to compressive stresses. A framework is presented which couples the uniaxial magnetomechanical model with a finite element package, and was used successfully to predict experimentally measured magnetization changes on a complex sample. These results show that a 1-D magnetomechanical model can be applied to predict 3-D magnetization changes due to stress, if adequately coupled.

Burgy, Christopher Donald

413

NASA Technical Reports Server (NTRS)

The electromagnetic effects of conventional dielectrics, anisotropic dielectrics, and metamaterials were modeled in a terahertz-frequency folded-waveguide slow-wave circuit. Results of attempts to utilize these materials to increase efficiency are presented.

Starinshak, David P.; Smith, Nathan D.; Wilson, Jeffrey D.

2008-01-01

414

Observation and Modeling of Mars Crustal Magnetism

Mars Global Surveyor's (MGS) magnetometer\\/electron reflectometer (MAG\\/ER) investigation mapped regions of intensely magnetized crust on Mars. The most intense crustal fields were observed over the ancient southern highlands but significant fields were observed over most of the planet. The most accurate magnetic field maps were compiled using data acquired during MGS mapping orbit at approximately 400 km altitude, owing to

J. E. Connerney; J. Espley; M. Acuna

2009-01-01

415

Modeling of permanent magnet motor drives

Research has indicated that the permanent magnet motor drives, which include the permanent magnet synchronous motor (PMSM) and the brushless DC motor (BDCM) could become serious competitors to the induction motor for servo applications. The PMSM has a sinusoidal back EMF and requires sinusoidal stator currents to produce constant torque while the BDCM has a trapezoidal back EMF and requires

PRAGASAN PILLAY; R. Krishnan

1988-01-01

416

ADVANCED ELECTRIC AND MAGNETIC MATERIAL MODELS FOR FDTD ELECTROMAGNETIC CODES

The modeling of dielectric and magnetic materials in the time domain is required for pulse power applications, pulsed induction accelerators, and advanced transmission lines. For example, most induction accelerator modules require the use of magnetic materials to provide adequate Volt-sec during the acceleration pulse. These models require hysteresis and saturation to simulate the saturation wavefront in a multipulse environment. In high voltage transmission line applications such as shock or soliton lines the dielectric is operating in a highly nonlinear regime, which require nonlinear models. Simple 1-D models are developed for fast parameterization of transmission line structures. In the case of nonlinear dielectrics, a simple analytic model describing the permittivity in terms of electric field is used in a 3-D finite difference time domain code (FDTD). In the case of magnetic materials, both rate independent and rate dependent Hodgdon magnetic material models have been implemented into 3-D FDTD codes and 1-D codes.

Poole, B R; Nelson, S D; Langdon, S

2005-05-05

417

NASA Astrophysics Data System (ADS)

In this paper test apparatus with experimental loop, containing model of primary circuit (lithium, sodium) and secondary circuit (potassium and potassium vapor) of power system for space based on Rankine thermodynamic cycle is presented. The history and multi-years experience with these types of facilities are described for the whole system and its particular components (steam generators, vapor condensers, electromagnetic pumps, devices for potassium cleaning from impurities etc.), instrumentation and methods for measurement. Simulated nuclear heat sources in the form of a high-frequency electric heater and its operation characteristics are examined. Historical insights and lessons learned from work of several technological laboratories over a twenty year period give material and information for adequate evaluation of status in considered area. .

Fedorovich, Evgeny D.; Kudriavtsev, Igor; Repnikova, Elena A.

2002-01-01

418

Modeling the magnetic interactions between paramagnetic beads in magnetorheological fluids

In this study, we develop and compare new and existing methods for computing the magnetic interactions between paramagnetic particles in magnetorheological (MR) fluids. The commonly employed point-dipole methods are outlined and the inter-particle magnetic forces, given by these representations, are compared with exact values. An alternative finite-dipole model, where the magnetization of a particle is represented as a distribution of

Eric E. Keaveny; Martin R. Maxey

2008-01-01

419

Magnetic field measurements of 1. 5 meter model SSC collider dipole magnets at Fermilab

Magnetic field measurements have been performed at Fermilab on 1.5 m magnetic length model dipoles for the Superconducting Supercollider. Harmonic measurements are recorded at room temperature before and after the collared coil is assembled into the yoke and at liquid helium temperature. Measurements are made as a function of longitudinal position and excitation current. High field data are compared with room temperature measurements of both the collared coil and the completed yoked magnet and with the predicted fields for both the body of the magnet and the coil ends.

Lamm, M.J.; Bleadon, M.; Coulter, K.J.; Delchamps, S.; Hanft, R.; Jaffery, T.S.; Kinney, W.; Koska, W.; Ozelis, J.P.; Strait, J.; Wake, M. (Fermi National Accelerator Lab., Batavia, IL (United States)); DiMarco, J. (Superconducting Super Collider Lab., Dallas, TX (United States))

1991-09-01

420

Phenomenological band structure model of magnetic coupling in semiconductors

Phenomenological band structure model of magnetic coupling in semiconductors Gustavo M. Dalpian a,1 the magnetic ordering in Mn-doped semiconductors. This model is based on the pÂd and dÂd level repulsions doped IIÂVI and IIIÂV semiconductors such as CdTe, GaAs, ZnO, and GaN. The model can also be used

Gong, Xingao

421

Exercise training is widely used for neurorehabilitation of Parkinson’s disease (PD). However, little is known about the functional reorganization of the injured brain after long-term aerobic exercise. We examined the effects of 4 weeks of forced running wheel exercise in a rat model of dopaminergic deafferentation (bilateral, dorsal striatal 6-hydroxydopamine lesions). One week after training, cerebral perfusion was mapped during treadmill walking or at rest using [14C]-iodoantipyrine autoradiography. Regional cerebral blood flow-related tissue radioactivity (rCBF) was analyzed in three-dimensionally reconstructed brains by statistical parametric mapping. In non-exercised rats, lesions resulted in persistent motor deficits. Compared to sham-lesioned rats, lesioned rats showed altered functional brain activation during walking, including: 1. hypoactivation of the striatum and motor cortex; 2. hyperactivation of non-lesioned areas in the basal ganglia-thalamocortical circuit; 3. functional recruitment of the red nucleus, superior colliculus and somatosensory cortex; 4. hyperactivation of the ventrolateral thalamus, cerebellar vermis and deep nuclei, suggesting recruitment of the cerebellar-thalamocortical circuit; 5. hyperactivation of limbic areas (amygdala, hippocampus, ventral striatum, septum, raphe, insula). These findings show remarkable similarities to imaging findings reported in PD patients. Exercise progressively improved motor deficits in lesioned rats, while increasing activation in dorsal striatum and rostral secondary motor cortex, attenuating a hyperemia of the zona incerta and eliciting a functional reorganization of regions participating in the cerebellar-thalamocortical circuit. Both lesions and exercise increased activation in mesolimbic areas (amygdala, hippocampus, ventral striatum, laterodorsal tegmental n., ventral pallidum), as well as in related paralimbic regions (septum, raphe, insula). Exercise, but not lesioning, resulted in decreases in rCBF in the medial prefrontal cortex (cingulate, prelimbic, infralimbic). Our results in this PD rat model uniquely highlight the breadth of functional reorganizations in motor and limbic circuits following lesion and long-term, aerobic exercise, and provide a framework for understanding the neural substrates underlying exercise-based neurorehabilitation. PMID:24278239

Wang, Zhuo; Myers, Kalisa G.; Guo, Yumei; Ocampo, Marco A.; Pang, Raina D.; Jakowec, Michael W.; Holschneider, Daniel P.

2013-01-01

422

Numerical modeling of higher order magnetic moments in UXO discrimination

The surface magnetic anomaly observed in unexploded ordnance (UXO) clearance is mainly dipolar, and consequently, the dipole is the only magnetic moment regularly recovered in UXO discrimination. The dipole moment contains information about the intensity of magnetization but lacks information about the shape of the target. In contrast, higher order moments, such as quadrupole and octupole, encode asymmetry properties of the magnetization distribution within the buried targets. In order to improve our understanding of magnetization distribution within UXO and non-UXO objects and to show its potential utility in UXO clearance, we present a numerical modeling study of UXO and related metallic objects. The tool for the modeling is a nonlinear integral equation describing magnetization within isolated compact objects of high susceptibility. A solution for magnetization distribution then allows us to compute the magnetic multipole moments of the object, analyze their relationships, and provide a depiction of the anomaly produced by different moments within the object. Our modeling results show the presence of significant higher order moments for more asymmetric objects, and the fields of these higher order moments are well above the noise level of magnetic gradient data. The contribution from higher order moments may provide a practical tool for improved UXO discrimination. ?? 2008 IEEE.

Sanchez, V.; Yaoguo, L.; Nabighian, M.N.; Wright, D.L.

2008-01-01

423

Magnetization in MSMA: 2D modeling and experimental characterization

NASA Astrophysics Data System (ADS)

Magnetic Shape Memory Alloys (MSMAs) are a type of smart material that exhibit a large amount of recoverable strain when subjected to an applied compressive stress in the presence of a magnetic field or an applied magnetic field in the presence of a compressive stress. These macroscopic recoverable strains are the result of the reorientation of tetragonal martensite variants. Potential applications for MSMAs include power harvesters, sensors, and actuators. For these applications, the stress is assumed to be applied only in the axial direction, and the magnetic field is assumed to be applied only in the transverse direction. To realize the full potential of MSMA and optimize designs, a mathematical model that can predict the material response under all potential loading conditions is needed. Keifer and Lagoudas [1, 2] developed a phenomenological model that characterizes the response of the MSMA to axial compressive stress and transversely applied magnetic field based on thermodynamic principles. In this paper, a similar thermodynamic framework is used. However, a simpler hardening function is proposed based on the observation that the reorientation phenomenon is the same in both forward and reverse loading, as well as under both magnetic and mechanical loading. The magnetic domains are redefined to more accurately reflect the magnetic field measured experimentally [3]. This revised model is shown to adequately predict the magneto-mechanical response of the MSMA in 2D loading, i.e. axial compressive stress and transversely applied magnetic field.

LaMaster, Douglas H.; Feigenbaum, Heidi P.; Nelson, Isaac D.; Ciocanel, Constantin

2013-04-01

424

Modeling the efficiency of a magnetic needle for collecting magnetic cells

NASA Astrophysics Data System (ADS)

As new magnetic nanoparticle-based technologies are developed and new target cells are identified, there is a critical need to understand the features important for magnetic isolation of specific cells in fluids, an increasingly important tool in disease research and diagnosis. To investigate magnetic cell collection, cell-sized spherical microparticles, coated with superparamagnetic nanoparticles, were suspended in (1) glycerine-water solutions, chosen to approximate the range of viscosities of bone marrow, and (2) water in which 3, 5, 10 and 100% of the total suspended microspheres are coated with magnetic nanoparticles, to model collection of rare magnetic nanoparticle-coated cells from a mixture of cells in a fluid. The magnetic microspheres were collected on a magnetic needle, and we demonstrate that the collection efficiency versus time can be modeled using a simple, heuristically-derived function, with three physically-significant parameters. The function enables experimentally-obtained collection efficiencies to be scaled to extract the effective drag of the suspending medium. The results of this analysis demonstrate that the effective drag scales linearly with fluid viscosity, as expected. Surprisingly, increasing the number of non-magnetic microspheres in the suspending fluid results increases the collection of magnetic microspheres, corresponding to a decrease in the effective drag of the medium.

Butler, Kimberly S.; Adolphi, Natalie L.; Bryant, H. C.; Lovato, Debbie M.; Larson, Richard S.; Flynn, Edward R.

2014-07-01

425

Field Weakening in Buried Permanent Magnet AC Motor Drives

The usual uncoupled d - q model of salient pole synchronous machines (Park's model) may be insufficient for accurate modeling of buried magnet permanent magnet machines. The addition of a nonbilateral coupling between the direct and quadrature axis equivalent circuits is shown to improve the steady-state model greatly. The cross coupling reactance has important implications in improving operation in the

Brigette Sneyers; Donald W. Novotny; Thomas A. Lipo

1985-01-01

426

Quantum Hall effect of Haldane model under magnetic field

NASA Astrophysics Data System (ADS)

Haldane model can realize the anomalous quantum Hall effect (QHE) without Landau levels (LLs) and serves as a prototype of the quantum spin Hall effect. In this paper, we study the QHE of Haldane model under magnetic field with magnitude such that the magnetic flux in a plaquette is commensurate with the lattice structure. First, we show the origin of unconventional QHE in graphene and point out a general rule for the Hall step of Dirac fermions, which strongly depends on the valley degeneracy of each LL. Second, we study the conductance around the neutral point which lies in the gap given by continuous bands, revealing the competition between periodic magnetic flux and uniform magnetic field. Moreover, the redistribution behavior of Chern number is investigated. We find that besides the staggered magnetic flux, the next-nearest-neighbor hopping can also induce the redistribution. We also study the QHE of the extended Haldane model on a square lattice.

Wang, Yi-Xiang; Li, Fu-Xiang; Wu, Ya-Min

2014-01-01

427

NSDL National Science Digital Library

Here you can learn about the major components of a circuit, as well as how different types of electricity and circuits affect the flow of electrons. electron flow The most basic type of circuit can be formed with a source of electrons and a resistance. This can be done by using two different types of metals and a lemon. The bars of metal are pushed into the lemons, and then are connected to a resistance. The two ...

Mr. Syracuse

2007-11-03

428

NASA Astrophysics Data System (ADS)

A simple analytical expression for the above threshold voltage drain current is derived in nanocrystalline silicon thin-film transistors (TFTs), based on an exponential energy distribution of band tail states. When the characteristic temperature distribution of the band tails is equal to 1.5 times the lattice temperature, the derived expression leads to the basic "quadratic" metal-oxide-semiconductor current expression. By including the impact ionization effect and using the same trap distribution parameters, the model describes adequately the output characteristics of TFTs with different channel dimensions, making the proposed model suitable for the design of circuits with nc-Si TFTs.

Pappas, I.; Dimitriadis, C. A.; Templier, F.; Oudwan, M.; Kamarinos, G.

2007-04-01

429

A macroscopic model for magnetic shape-memory single crystals

NASA Astrophysics Data System (ADS)

A rate-independent model for the quasi-static magneto-elastic evolution of a magnetic shape-memory single crystal is presented. In particular, the purely mechanical Souza-Auricchio model for shape-memory alloys is here combined with classical micro-magnetism by suitably associating magnetization and inelastic strain. By balancing the effect of conservative and dissipative actions, a nonlinear evolution PDE system of rate-independent type is obtained. We prove the existence of so-called energetic solutions to this system. Moreover, we discuss several limits for the model corresponding to parameter asymptotics by means of a rigorous ?-convergence argument.

Bessoud, Anne-Laure; Kružík, Martin; Stefanelli, Ulisse

2013-04-01

430

Model for dynamic self-assembled magnetic surface structures.

We propose a first-principles model for the dynamic self-assembly of magnetic structures at a water-air interface reported in earlier experiments. The model is based on the Navier-Stokes equation for liquids in shallow water approximation coupled to Newton equations for interacting magnetic particles suspended at a water-air interface. The model reproduces most of the observed phenomenology, including spontaneous formation of magnetic snakelike structures, generation of large-scale vortex flows, complex ferromagnetic-antiferromagnetic ordering of the snake, and self-propulsion of bead-snake hybrids.

Belkin, M.; Glatz, A.; Snezhko, A.; Aranson, I. S.; Materials Science Division; Northwestern Univ.

2010-07-07

431

FDTD modeling of digital signal propagation in 3-D circuits with passive and active loads

Most existing computer-aided circuit design tools are limited when digital clock speeds exceed several hundred MHz. These tools may not deal effectively with the physics of UHF and microwave electromagnetic wave energy transport along metal surfaces such as ground planes or in the air away from metal paths that are common at or above this frequency range. In this paper,

Melinda Piket-May; Allen Taflove; John Baron

1994-01-01

432

Modelling and Application of Secondary Circuit Signals for Power Grid Intelligent Alarm

Power grid intelligent alarm and fault diagnosis program mainly use breaker and relay action alarms. However, there may be misoperations existed in relays, which could leads to incorrect diagnosis results. With the development of digital substation and application of IEC61850, the secondary circuit signals are available from integrated automation system in substation. These signals may imply control or interlock relationship

Kang Taifeng; Wu Wenchuan; Sun Hongbin; Zhang Boming; Li Jingxiong

2010-01-01

433

ERIC Educational Resources Information Center

Drosophila larvae combine a numerically simple brain, a correspondingly moderate behavioral complexity, and the availability of a rich toolbox for transgenic manipulation. This makes them attractive as a study case when trying to achieve a circuit-level understanding of behavior organization. From a series of behavioral experiments, we suggest a…

Schleyer, Michael; Saumweber, Timo; Nahrendorf, Wiebke; Fischer, Benjamin; von Alpen, Desiree; Pauls, Dennis; Thum, Andreas; Gerber, Bertram

2011-01-01

434

An efficient wavelet-based nonlinear circuit simulation technique with model order reduction

This paper proposes further improvement to a novel method for the analysis and simulation of ICs recently proposed by the authors. The circuits are assumed to be subjected to input signals that have widely separated rates of variation, e.g. in communication systems an RF carrier modulated by a low-frequency information signal. The previously proposed technique enables the reuse of the

Emira Dautbegovic; Marissa Condon; Conor Brennan

2004-01-01

435

An Environmentally Benign Process Model Development for Printed Circuit Board Recycling

Delaminating and separation of obsolete printed circuit board (PCB) is essential for its recycling. This paper presents an alternative environmentally benign process method for PCB recycling. Applying the solvent system, e.g. carbon dioxide and water under certain pressure and temperature, the PCB scraps could be delaminated easily. The separation of PCB into copper foil, glass fiber and polymer will be

Hong-Chao Zhang; Xi Ouyang; Alex Abadi

2006-01-01

436

Modeling and Simulation Methodology Techniques for Advanced Low Power Communication Circuits

This paper targets heterogeneous low power communication circuits and Systems that will be used in the future generations' hand-held devices (PDA's, mobile phones). Those platforms will probably contain a few studies have emerged and considerable amount of on-chip memories. An optimized communication architecture will be required to interconnect them efficiently. Many communication architectures have been proposed in the literature: shared

Salah-ddine Krit; Jalal Laassiri; Said El Hajji

2011-01-01

437

Uniform model for series RL and parallel RL shunt circuits and power consumption

A simple impedance based analysis is presented for resonant shunt circuits. The formulation is compatible with arrangement of shunt electronics and is used to clarify previously published resonance condition and to examine power. Since our resonance condition is contrary to previously published results, experimental verification is also presented. The experiments consist of both a series and parallel second mode absorber

Chul H. Park; Daniel J. Inman

1999-01-01

438

An evaluation of recent internal field models. [of earth magnetism

NASA Technical Reports Server (NTRS)

The paper reviews the current status of internal field models and evaluates several recently published models by comparing their predictions with annual means of the magnetic field measured at 140 magnetic observatories from 1973 to 1977. Three of the four models studied, viz. AWC/75, IGS/75, and Pogo 8/71, were nearly equal in their ability to predict the magnitude and direction of the current field. The fourth model, IGRF 1975, was significantly poorer in its ability to predict the current field. All models seemed to be able to extrapolate predictions quite well several years outside the data range used to construct the models.

Mead, G. D.

1979-01-01

439

NSDL National Science Digital Library

Circuit Sage aims to be "a complete source of information to help you design great circuits fast." Visitors can link on a circuit diagram or categories listed on the sidebar to learn more about various aspects of circuitry. Topics include A/D, Bandgap, Filter, Inductor, and Transceiver Design. The number of resources is a bit mind-boggling, ranging from articles, to software (for purchase), and online tools. Another section offers a "Routine of the Week" to help you mathematically size your circuit.

440

Modeling of a Magnetorheological Actuator Including Magnetic Hysteresis

Magnetorheological (MR) actuators provide controlled torque through control of an applied magnetic field. Therefore knowledge of the relationship between the applied current and output torque is required. This paper presents a new nonlinear modeling of MR actuators considering magnetic hysteresis to determine the torque-current nonlinear relationship. Equations for transmitted torque are derived according to mechanical shear configurations of the MR

Jinung An; Dong-Soo Kwon

2003-01-01

441

Toward a transport model of collisionless magnetic reconnection

An absence of theoretical justification for the magnitude of resistivity is one of the major limitations of large-scale simulations of magnetic reconnection in collisionless magnetospheric plasma. We took advantage of the results of recent progress in kinetic modeling of collisionless dissipation in the vicinity of the magnetically neutral X point aiming to find ways to represent small-scale kinetic effects in

Masha M. Kuznetsova; Michael Hesse; Dan Winske

2000-01-01

442

Collisionless magnetic reconnection: Electron processes and transport modeling

Particle-in-cell simulations are used to investigate collisionless magnetic reconnection in thin current sheets, based on the configuration chosen for the Geospace Environment Modeling (GEM) magnetic reconnection challenge [Birn et al., this issue]. The emphasis is on the overall evolution, as well as details of the particle dynamics in the diffusion region. Here electron distributions show clear signatures of nongyrotropy, whereas

Michael Hesse; Joachim Birn; Masha Kuznetsova

2001-01-01

443

Polygonal current model: an effective quantifier of aromaticity on the magnetic criterion.

To explain peculiar effects of electron delocalization on the magnetic response of planar cyclic molecules, a basic model that accounts for their actual geometrical structure has been developed by integrating the differential Biot-Savart law. Such a model, based on a single polygonal circuit with ideal features, is shown to be applicable to electrically neutral or charged monocyclic compounds, as well as linear polycyclic condensed hydrocarbons. Two theoretical quantities, easily computed via quantum chemistry codes (the out-of-plane components of the magnetizability, ??, and the magnetic shielding ??(h) of points P on the symmetry axis orthogonal to the molecular plane, at distance h from the center of mass) are shown to be linearly connected, for example, for monocyclic structures, via the relationship ??(h) = ±(?0/2?)??D(h), where D(h) is a simple function of geometrical parameters. Equations of this type are useful to rationalize scan profiles of magnetic shielding and nucleus-independent chemical shift along the highest symmetry axis. For a regular polygon, D(h) depends approximately on the third inverse power of the distance d of the vertices from the center, and ?? is proportional to the area of the polygon, that is, ?d(2); hence, the shielding ??(0) and the related nucleus-independent chemical shift NICS?(0) are unsafe quantifiers of magnetotropicity; they are biased by a spurious geometrical dependence on d(-1), incorrectly exhalting them in cyclic systems with smaller size. A more reliable magnetotropicity measure for a cyclic compound, in the presence of a magnetic field Bext applied at right angles to the molecular plane, is defined within the polygonal current model by the current susceptibility or current strength, ?I/?Bext = -??/Aeff, expressed in nanoampère per tesla, where Aeff is a properly defined area enclosed with the polygonal circuit. An extended numerical test on a wide series of mono- and polycyclic compounds and a comparison with corresponding ab initio current susceptibilities prove the superior quality of this indicator over other commonly employed aromaticity/antiaromaticity benchmarks on the magnetic criterion. PMID:23952986

Pelloni, Stefano; Lazzeretti, Paolo

2013-09-19

444

Power-Invariant Magnetic System Modeling

: Chair of Committee, Mehrdad Ehsani Committee Members, Karen Butler-Purry Shankar Bhattacharyya Reza Langari Head of Department, Costas Georghiades August 2011 Major Subject: Electrical Engineering iii ABSTRACT Power-Invariant Magnetic...

Gonzalez Dominguez, Guadalupe Giselle

2012-10-19

445

Phenomenological modelling of first order phase transitions in magnetic systems

NASA Astrophysics Data System (ADS)

First order phase transitions may occur in several magnetic systems, with two structural phases having different magnetic properties each and a structural transition between them. Here, a novel physics based phenomenological model of such systems is proposed, in which magnetization is represented by the volumetric amounts of ferromagnetism (described by extended Jiles-Atherton theory) and paramagnetism (described by the Curie-Weiss law) in respective phases. An identification procedure to extract material parameters from experimental data is proposed. The proposed phenomenological approach was successfully applied to magnetocaloric Gd5(SixGe1-x)4 system and also has the potential to describe the behavior of Griffiths phase magnetic systems.

Melikhov, Yevgen; Hadimani, R. L.; Raghunathan, Arun

2014-05-01

446

Magnetization plateaus in generalized Shastry-Sutherland models

NASA Astrophysics Data System (ADS)

We study an anisotropic Heisenberg antiferromagnet with ferromagnetic transverse spin exchange using exact quantum Monte Carlo methods. Such a model is relevant to a class of rare earth tetraboride materials that display a range of magnetization plateaus under applied magnetic field. The layered arrangement of magnetic ions in these materials is topologically equivalent to the Shastry-Sutherland lattice. In this frustrated geometry, we study the interplay of next-nearest neighbor interactions in stabilizing a plateau at half the saturation magnetization (or 1/2 plateau). We also show hysteresis-like behavior at the onset of the 1/3 plateau.

Wierschem, Keola; Sengupta, Pinaki

2013-08-01

447

Mars environment and magnetic orbiter model payload

Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission.\\u000a The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions\\u000a essential to understand planetary evolution, the appearance of life and its sustainability. MEMO provides a high-resolution,\\u000a complete, mapping of the magnetic

B. Langlais; F. Leblanc; T. Fouchet; S. Barabash; D. Breuer; E. Chassefière; A. Coates; V. Dehant; F. Forget; H. Lammer; S. Lewis; M. Lopez-Valverde; M. Mandea; M. Menvielle; A. Pais; M. Paetzold; P. Read; C. Sotin; P. Tarits; S. Vennerstrom; G. Branduardi-Raymont; G. Cremonese; J. G. M. Merayo; T. Ott; H. Rème; J. G. Trotignon; J. E. Walhund

2009-01-01

448

A technique for evaluating the application of the pin-level stuck-at fault model to VLSI circuits

NASA Technical Reports Server (NTRS)

Accurate fault models are required to conduct the experiments defined in validation methodologies for highly reliable fault-tolerant computers (e.g., computers with a probability of failure of 10 to the -9 for a 10-hour mission). Described is a technique by which a researcher can evaluate the capability of the pin-level stuck-at fault model to simulate true error behavior symptoms in very large scale integrated (VLSI) digital circuits. The technique is based on a statistical comparison of the error behavior resulting from faults applied at the pin-level of and internal to a VLSI circuit. As an example of an application of the technique, the error behavior of a microprocessor simulation subjected to internal stuck-at faults is compared with the error behavior which results from pin-level stuck-at faults. The error behavior is characterized by the time between errors and the duration of errors. Based on this example data, the pin-level stuck-at fault model is found to deliver less than ideal performance. However, with respect to the class of faults which cause a system crash, the pin-level, stuck-at fault model is found to provide a good modeling capability.

Palumbo, Daniel L.; Finelli, George B.

1987-01-01

449

and one random finite network in certain directions of the applied magnetic field. But their ap- proach is cruder than the Ginzburg-Landau theory (in the sense that they did not allow the magnitude of the su- perconducting order parameter to vary... ex- act analytic solution, so we can present a more thorough and accurate study of the dependence of the phase boundary on the magnitude and direction of the applied magnetic field. In the mean-field (i.e., Ginzburg ?Landau ?de Gennes) approach...

Hu, Chia-Ren; HUANG, CH.

1991-01-01

450

Modeling high gradient magnetic separation from biological fluids.

A proposed portable magnetic separator consists of an array of biocompatible capillary tubing and magnetizable wires immersed in an externally applied homogeneous magnetic field. While subject to the homogeneous magnetic field, the wires create high magnetic field gradients, which aid in the collection of blood-borne magnetic nanospheres from blood flow. In this study, a 3-D numerical model was created using COMSOL Multiphysics 3.2 software to determine the configuration of the wire-tubing array from two possible configurations, one being an array with rows alternating between wires and tubing, and the other being an array where wire and tubing alternate in two directions. The results demonstrated that the second configuration would actually capture more of the magnetic spheres. Experimental data obtained by our group support this numerical result.

Bockenfeld, D.; Chen, H.; Rempfer, D.; Kaminski, M. D.; Rosengart, A. J.; Chemical Engineering; Illinois Inst. of Tech.; Univ. of Chicago, Pritzker School of Medicine

2006-01-01

451

Robust neural classifier circuits using asynchronous design

NASA Technical Reports Server (NTRS)

Aerospace neural circuits must be adaptive, offer a practical size-performance ratio, and be environmentally robust. Our approach to building such circuits combines asynchronous design with a new fuzzy/neural classifier model. Asynchronous circuits offer many design advantages for neural hardware and our hybrid fuzzy/neural model, using mainly min and max operators, promises a low circuit complexity. The general approach is described and a description of a use of rule-induction to further reduce circuit complexity is described.

Hurdle, John F.; Conwell, Peter R.; Brunvand, Erik L.

1993-01-01

452

Analysis and Detection of Short Circuits in Fractional Horsepower Commutator Machines

An improved mathematical model for transient simulations of commutator machines is presented in this paper. This model can simulate and predict the line current harmonics during healthy and faulty operation conditions. A lumped parameter model that considers every single coil in the stator and rotor as a separate electrical and magnetic circuit is proposed. Self and mutual inductances of the

Roberto Retana; Anton Paweletz; Hans-Georg Herzog

2008-01-01

453

Infrared polarimetry and the Galactic magnetic field. II - Improved models

NASA Astrophysics Data System (ADS)

Two models of the Galactic magnetic field are developed in order to account for the observed trend in interstellar polarization with extinction at 2l2 microns. It is shown that the trend can be well accounted for by assuming that there is no dependence of the polarization on field strength and that the large elongated dust grains are everywhere 100 percent aligned. A model for the magnetic field using Alfven waves works best when there is equipartition between the magnetic and turbulent energy densities. A model invoking vector addition of a constant component and a random component works best when there is equal energy density in the two components. Both models do well in matching the observed dispersion in polarization magnitude and the observed dispersion in position angle. The path length over which the magnetic field decorrelates must be tied to the total path, not the physical path length. Two simple cloud compression scenarios may explain this finding.

Jones, Terry J.; Klebe, Dimitri; Dickey, John M.

1992-04-01

454

The moon's permanent magnetic field - A cratered-shell model

NASA Technical Reports Server (NTRS)

The possibility is considered that the properties of the larger-scale lunar magnetic field may depend in a rather straightforward manner on the geometrical properties of the distribution of larger craters. The relevant effects of cratering are analyzed in the framework of a model of a spherically symmetric shell magnetized to some specific intensity by a concentric dipolar magnetic field. The remanent dipole moment of the model is determined by calculating the dipole moment of the material removed to form craters and them computing the remanent dipole moment for three mutually orthogonal orientations of the magnetizing dipole. The resulting absolute values for the remanent dipole moment are found to be comparable to the upper limit of 10 to the -19th power G-cu cm estimated from Apollo subsatellite measurements. It is concluded that for a crust with an empirically reasonable mean magnetization, the craters can account for a dipole moment as great as that indicated by the estimated upper limit.

Weiss, H.; Coleman, P. J., Jr.

1977-01-01

455

The theme of the paper is the use of commutative Frobenius algebras in braided strict monoidal categories in the study of varieties of circuits and communicating systems which occur in Computer Science, including circuits in which the wires are tangled. We indicate also some possible novel geometric interest in such algebras.

Rosebrugh, R; Walters, R F C

2011-01-01

456

NASA Astrophysics Data System (ADS)

Computational methods are considered for the time- and frequency-domain simulations of a microwave power amplifier with a transistor built on a diamond-like semiconductor. The first method is based only on a two-dimensional model of the intrinsic transistor that includes the quasi-hydrodynamic model of electron transport and electric field equations. The second method, which is less accurate but much more computer-time-saving, is based on the intrinsic transistor large-signal lumped-element equivalent circuit model with the parameters and spline characteristics calculated by means of the abovementioned two-dimensional model. Using these two methods, the microwave parameters of the amplifier are calculated for frequencies varying from 15 to 90 GHz. When using the equivalent circuit at frequencies of up to 60 GHz, the calculation error (equal to the difference between the results of the time- and frequency-domain simulations) does not exceed 5% for the input impedance and 0.6 dB for the transducer power gain.

Garber, Gennadiy Z.

2015-01-01

457

Cosmic Acceleration and Anisotropic models with Magnetic field

Plane symmetric cosmological models are investigated with or without any dark energy components in the field equations. Keeping an eye on the recent observational constraints concerning the accelerating phase of expansion of the universe, the role of magnetic field is assessed. In the absence of dark energy components, magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters. In presence of dark energy components in the form of a time varying cosmological constant, the influence of magnetic field is found to be limited.

S. K. Tripathy; K. L. Mahanta

2014-12-10

458

The use of geomagnetic field models in magnetic surveys

NASA Technical Reports Server (NTRS)

The importance of global geomagnetic field models for the reduction of magnetic surveys is discussed. It is demonstrated that a numerical model with adequate secular variation correction, provides a suitable representation of the regional field. The limitations of the presently available models are reported, with emphasis on the International Geomagnetic Reference Field.

Regan, R. D.; Gain, J. C.

1974-01-01

459

Accounting for crustal magnetization in models of the core magnetic field

NASA Technical Reports Server (NTRS)

The problem of determining the magnetic field originating in the earth's core in the presence of remanent and induced magnetization is considered. The effect of remanent magnetization in the crust on satellite measurements of the core magnetic field is investigated. The crust as a zero-mean stationary Gaussian random process is modelled using an idea proposed by Parker (1988). It is shown that the matrix of second-order statistics is proportional to the Gram matrix, which depends only on the inner-products of the appropriate Green's functions, and that at a typical satellite altitude of 400 km the data are correlated out to an angular separation of approximately 15 deg. Accurate and efficient means of calculating the matrix elements are given. It is shown that the variance of measurements of the radial component of a magnetic field due to the crust is expected to be approximately twice that in horizontal components.

Jackson, Andrew

1990-01-01

460

A Model for the Behavior of Magnetic Tunnel Junctions

A magnetic tunnel junction is a device that changes its electrical resistance with a change in an applied magnetic field. A typical junction consists of two magnetic electrodes separated by a nonmagnetic insulating layer. The magnetizations of the two electrodes can have two possible extreme configurations, parallel and antiparallel. The antiparallel configuration is observed to have the higher measured resistance and the parallel configuration has the lower resistance. To switch between these two configurations a magnetic field is applied to the device which is primarily used to change the orientation of the magnetization of one electrode usually called the free layer, although with sufficient high magnetic field the orientation of the magnetizations of both of the electrodes can be changed. The most commonly used models for describing and explaining the electronic behavior of tunnel junctions are the Simmons model and the Brinkman model. However, both of these models were designed for simple, spin independent tunneling. The Simmons model does not address the issue of applied magnetic fields nor does it address the form of the electronic band structure in the metallic electrodes, including the important factor of spin polarization. The Brinkman model is similar, the main difference between the two models being the shape of the tunneling barrier potential between the two electrodes. Therefore, the research conducted in this thesis has developed a new theoretical model that addresses these important issues starting from basic principles. The main features of the new model include: the development of equations for true spin dependent tunneling through the insulating barrier, the differences in the orientations of the electrode magnetizations on either side of the barrier, and the effects of the density of states function on the behavior of the junction. The present work has explored densities of states that are more realistic than the simplified free electron density of states function, and has developed an exact analytic solution for the case of an electron band of finite width. The approach taken in this thesis easily allows extension to cases where the band structure is different on either side of the barrier (known as heterojunctions) which are of greater interest in real magnetic tunnel junction devices rather than the simple, identical band structure devices.

Bryan John Baker

2003-08-05

461

Identification of Electrical Circuits for Realization of Sparsity Preserving Reduced

Identification of Electrical Circuits for Realization of Sparsity Preserving Reduced Order Models. This work starts with a description of the modelling of electrical circuits. Examples are given gained provide valuable information towards identification of electrical circuits suited for Sparse

462

Textural remanence - A new model of lunar rock magnetism

NASA Technical Reports Server (NTRS)

In reexamining the accumulated magnetic data on lunar rocks, several common patterns of magnetic behavior are recognized. Their joint occurrence strongly suggests a new model of lunar rock magnetism, which is based on partial preferred textural alignment of the spontaneous moments of magnetic grains without requiring the existence of ancient lunar magnetic fields. This magnetic fabric, mimetic to locally oriented petrofabric, gives rise to an apparent 'textural remanent magnetization'. In order to account for the observed intensity of 'stable remanence' in lunar rocks, only a minute fraction (0.001 to 0.00001) of the single-domain iron grains present need be preferentially aligned. Several mechanisms operating on the lunar surface, including shock and diurnal thermal cycling, appear adequate for producing the required type and degree of magnetic alignment in all lunar rock classes. The model is supported by a wide variety of direct and indirect evidence, and its predictions (e.g., regarding anisotropic susceptibility and remanence acquisition) can be experimentally tested.

Brecher, A.

1976-01-01

463

Model of magnetic reconnection in space and astrophysical plasmas

Maxwell's equations imply that exponentially smaller non-ideal effects than commonly assumed can give rapid magnetic reconnection in space and astrophysical plasmas. In an ideal evolution, magnetic field lines act as stretchable strings, which can become ever more entangled but cannot be cut. High entanglement makes the lines exponentially sensitive to small non-ideal changes in the magnetic field. The cause is well known in popular culture as the butterfly effect and in the theory of deterministic dynamical systems as a sensitive dependence on initial conditions, but the importance to magnetic reconnection is not generally recognized. Two-coordinate models are too constrained geometrically for the required entanglement, but otherwise the effect is general and can be studied in simple models. A simple model is introduced, which is periodic in the x and y Cartesian coordinates and bounded by perfectly conducting planes in z. Starting from a constant magnetic field in the z direction, reconnection is driven by a spatially smooth, bounded force. The model is complete and could be used to study the impulsive transfer of energy between the magnetic field and the ions and electrons using a kinetic plasma model.

Boozer, Allen H. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

2013-03-15

464

Modelling and control of a rotor supported by magnetic bearings

NASA Technical Reports Server (NTRS)

In this paper we develop a dynamical model of a rotor and the active magnetic bearings used to support the rotor. We use this model to develop a stable state feedback control of the magnetic bearing system. We present the development of a rigid body model of the rotor, utilizing both Rotation Matrices (Euler Angles) and Euler Parameters (Quaternions). In the latter half of the paper we develop a stable state feedback control of the actively controlled magnetic bearing to control the rotor position under inbalances. The control law developed takes into account the variation of the model with rotational speed. We show stability over the whole operating range of speeds for the magnetic bearing system. Simulation results are presented to demonstrate the closed loop system performance. We develop the model of the magnetic bearing, and present two schemes for the excitation of the poles of the actively controlled magnetic bearing. We also present a scheme for averaging multiple sensor measurements and splitting the actuation forces amongst redundant actuators.

Gurumoorthy, R.; Pradeep, A. K.

1994-01-01

465

An analytical model has been developed for calculating the open-circuit time-varying magnetic field distribution in the airgap\\/magnet\\/retaining sleeve region of a brushless permanent magnet motor equipped with diametrically magnetised magnets. It accounts for the stator slotting and curvature, as well as for parasitic eddy currents induced in the retaining sleeve and magnets. The analytically predicted time-varying field distribution in the

K. Ng; Z. Q. Zhu; D. Howe

1996-01-01

466

A Magnetic Model for AGN engines

Standard quantum field theory predicts suppressing the effective mass of electrons, possibly to zero, in ultrastrong magnetic fields. The required field strength, several orders of magnitude above B{ QED}, is expected to occur in the cores of some magnetars, and in the final stages of a collapsar as it forms a black hole. Tachyon emission will then occur, the physical

P. N. Arendt; I. G. Avramidi

2002-01-01

467

Observational testing of magnetospheric magnetic field models at geosynchronous orbit

Empirical mode which estimate the magnetic field direction and magnitude at any point within the magnetosphere under a variety of conditions play an important role in space weather forecasting. We report here on a number of different studies aimed at quantitatively evaluating these models, and in particular the Tsyganenko T89a model. The models are evaluated in two basic ways: (1) by comparing the range of magnetic field tilt angles observed at geosynchronous orbit with the ranges predicted for the same locations by the models; and (2) by comparing the observed magnetic field mapping between the ionosphere and geosynchronous orbit (using two-satellite magnetic field conjunctions) with the model predictions at the same locations. We find that while the T89a model predicts reasonably well the basic variation in tilt angle with local time and permits a range of field inclinations adequate to encompass the majority of observed angles on the dawn, dusk, and night sides, it is unable to reproduce the range of inclinations on the dayside. The model also predicts a smaller magnetic latitude range of geosynchronous field line footpoints than the observed two-satellite mapping indicate. Together, these results suggest that the next generation of field models should allow a greater range of stretching, especially in local time sectors away from midnight. It is important to note, however, that any increased range should encompass less-stretched configurations: although there are certainly cases where the models are not sufficiently stretched, we find that on average all magnetic field models tested, including T89a, are too stretched. Finally, in investigating how well the observed degree of field stretch was ordered by various magnetospheric indices, we find that the tilt of the field at geosynchronous orbit is a promising candidate for the incorporation into future models.

Weiss, L.A.; Thomsen, M.F.; Reeves, G.D.; McComas, D.J.

1996-09-01

468

Hierarchical organization of parietofrontal circuits during goal-directed action.

Two parietofrontal networks share the control of goal-directed movements: a dorsomedial circuit that includes the superior parieto-occipital sulcus (sPOS) and a dorsolateral circuit comprising the anterior intraparietal sulcus (aIPS). These circuits are thought to independently control either reach and grip components (a functional dissociation), or planning and execution phases of grasping movements (a temporal dissociation). However, recent evidence of functional and temporal overlap between these circuits has undermined those models. Here, we test an alternative model that subsumes previous accounts: the dorsolateral and dorsomedial circuits operate at different hierarchical levels, resulting in functional and temporal dependencies between their computations. We asked human participants to grasp a visually presented object, manipulating movement complexity by varying object slant. We used concurrent single-pulse transcranial magnetic stimulation and electroencephalography (TMS-EEG) to probe and record neurophysiological activity in the two circuits. Changes in alpha-band oscillations (8-12 Hz) characterized the effects of task manipulations and TMS interferences over aIPS and sPOS. Increasing the complexity of the grasping movement was accompanied by alpha-suppression over dorsomedial parietofrontal regions, including sPOS, during both planning and execution stages. TMS interference over either aIPS or sPOS disrupted this index of dorsomedial computations; early when aIPS was perturbed, later when sPOS was perturbed, indicating that the dorsomedial circuit is temporally dependent on aIPS. TMS over sPOS enhanced alpha-suppression in inferior parietal cortex, indicating that the dorsolateral circuit can compensate for a transient sPOS perturbation. These findings suggest that both circuits specify the same grasping parameters, with dorsomedial computations depending on dorsolateral contributions. PMID:23575847

Verhagen, Lennart; Dijkerman, H Chris; Medendorp, W Pieter; Toni, Ivan

2013-04-10

469

NASA Technical Reports Server (NTRS)

An analytical model of an Annular Momentum Control Device (AMCD) laboratory test model magnetic bearing actuator with permanent magnet fluxbiasing is presented. An AMCD consists of a spinning annular rim which is suspended by a noncontacting linear electromagnetic spin motor. The actuator is treated as a lumped-parameter electromechanical system in the development of the model.