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Circuit Analysis (circuit + analysis)

Distribution by Scientific Domains

Engineering	85%

Selected Abstracts

DEADLOCK AVOIDANCE FOR FLEXIBLE MANUFACTURING SYSTEMS WITH CHOICES BASED ON DIGRAPH CIRCUIT ANALYSIS

ASIAN JOURNAL OF CONTROL, Issue 2 2007
Wenle Zhang
ABSTRACT Due to existence of concurrent part flows and resource sharing in modern automated flexible manufacturing systems (FMS), deadlock is a common problem and its occurrence causes loss of productivity. When a manufacturing system is modeled by a digraph, existence of circuits in such a graph is a necessary condition for deadlock. Our previous work further showed that the knot and order of a circuit is closely related to impending deadlocks , a type of deadlock that is more difficult to detect. In this paper, we extend our previous work on deadlock avoidance for flexible manufacturing systems to allow choices in process flows (a.k.a., flexible part routing). Due to introduction of choices, part flow dynamics become more sophisticated and our previous results are no longer valid. A systematic circuit analysis is performed in this paper. New concepts such as broken circuit, basic circuit, choice circuit and supremal circuit are introduced to reduce significantly the number of circuits thus improving efficiency of our approach. The extended method is highly permissive with the adjusted effective free space calculation to capture more necessary parts flow dynamics, especially when multiple knots exist in the digraph model. The online policy runs in polynomial time once the set of basic circuits of the digraph is computed offline. Simulation results on selected examples are given. [source]

Development of a high-speed electromagnetic repulsion mechanism for high-voltage vacuum circuit breakers

ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2008
Mitsuru Tsukima
Abstract This paper presents a design and testing of a new high-speed electromagnetic driving mechanism for a high-voltage vacuum circuit breaker (VCB). This mechanism is based on a high-speed electromagnetic repulsion and a permanent magnet spring (PMS). This PMS is introduced instead of the conventional disk spring due to its low spring energy and more suitable force characteristics for VCB application. The PMS has been optimally designed by the 3D nonlinear finite-elements magnetic field analysis and investigated its internal friction and eddy-current effect. Furthermore, we calculated the dynamic of this mechanism coupling with the electromagnetic field and circuit analysis, in order to satisfy the operating characteristics,contact velocity, response time, and so on, required for the high-speed VCB. A prototype VCB, which was built based on the above analysis, shows sufficient operating performance. Finally, the short circuit interruption tests were carried out with this prototype breaker, and we have been able to verify its satisfying performance. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(1): 34,40, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20398 [source]

Electrochemical Impedance Characterization of Nafion-Coated Carbon Film Resistor Electrodes for Electroanalysis

ELECTROANALYSIS, Issue 7 2005
Carla Gouveia-Caridade
Abstract Carbon film disk electrodes with Nafion coatings have been characterized by electrochemical impedance spectroscopy (EIS) with a view to a better understanding of their advantages and limitations in electroanalysis, particularly in anodic stripping voltammetry of metal ions. After initial examination by cyclic voltammetry, spectra were recorded over the full potential range in acetate buffer solution at the bare electrodes, electrodes electrochemically pretreated in acid solution, and Nafion-coated pretreated electrodes in the presence and absence of dissolved oxygen. EIS equivalent circuit analysis clearly demonstrated the changes between these electrode assemblies. In order to simulate anodic stripping voltammetry conditions, spectra were also obtained in the presence of cadmium and lead ions in solution at Nafion-coated electrodes, both after metal ion deposition and following re-oxidation. Permanent changes to the structure of the Nafion film occurred, which has implications for use of these electrode assemblies in anodic stripping voltammetry at relatively high trace metal ion concentrations. [source]

Temperature-frequency characteristics simulation of piezoelectric resonators and their equivalent circuits based on three-dimensional finite element modelling

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 6 2003
N. Wakatsuki
Abstract The electromechanical resonators made of piezoelectric crystals such as a quartz crystal are widely used for electronic devices. Their frequency,temperature characteristics are of primary importance for their applications to the frequency control devices. The present paper demonstrates numerical simulation for several types of resonators using 3-D Finite Element Modelling. The results are compared with the theoretical values whenever they are available. As they are electronic devices, the equivalent circuit representation is often favourable for describing the admittance at the electrical terminals which enables the circuit analysis including the effect of the temperature change by using commercially available circuit simulators. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Parameters estimation of the d.c. electrothermal model of the bipolar transistor

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 2 2002
Janusz Zar
Abstract This paper concerns the problems of the parameter values estimation of d.c. electrothermal model of the BJT formulated for circuit analysis with SPICE. In this case, PARTS software available in SPICE cannot be used. In the paper, a new estimation algorithm for d.c. electrothermal model of the BJT is proposed. The form of the electrothermal BJT model is also presented. The estimation algorithm implemented into the computer-controlled measurement set allows one to derive the values of the parameters automatically after the measurements of the selected isothermal characteristics and proper calculations. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Model order reduction of linear and nonlinear 3D thermal finite-element description of microwave devices for circuit analysis

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2005
Raphaël Sommet
Abstract Electrothermal models of power devices are necessary for the accurate analysis of their performances. For this reason, this article deals with a methodology to obtain an electrothermal model based on a reduced model of a 3D thermal finite-element (FE) description for its thermal part and on pulsed electrical measurements for its electrical part. The reduced thermal model is based on the Ritz vector approach, which ensures a steady-state solution in every case. An equivalent SPICE subcircuit implementation for circuit simulation is proposed and discussed. An extension of the method to a nonlinear reduced model based on the Kirchoff transformation is also proposed. The complete models have been successfully implemented in circuit simulators for several HBT or PHEMT device structures. Many results concerning devices and circuits are presented, including simulation of both the static and dynamic collector-current collapse in HBTs due to the thermal phenomenon. Moreover, the results in terms of the circuit for an X-band high-power amplifier are also presented. As for the nonlinear approach, results concerning an homogeneous structure is given. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]