The paper introduces a novel numerical approach to the simulation of nonlinear microwave circuits containing temperature-dependent active devices. Making use of an extension of the classic piecewise harmonic-balance t...
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The paper introduces a novel numerical approach to the simulation of nonlinear microwave circuits containing temperature-dependent active devices. Making use of an extension of the classic piecewise harmonic-balance technique, the analysis is reduced to a nonlinear algebraic solving system whose unknowns are electrical and thermal state-variable harmonics. The solution simultaneously provides the circuit electrical regime and the device thermal regimes.
A high performance, 0.8 μm, analog-digital technology is presented. Telecommunication circuit and system diversity has been accommodated by incorporating modular device options into a triple-level-metal BiCMOS process.
A high performance, 0.8 μm, analog-digital technology is presented. Telecommunication circuit and system diversity has been accommodated by incorporating modular device options into a triple-level-metal BiCMOS process.
AuGeNi and AuZnNi metallizations to n- and p-InP were studied as a function of the annealing temperature in a Rapid Thermal Annealing (RTA) system. For n-InP (S:8x10 18 cm -3 ) a broad minimum existed from 385°C ...
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AuGeNi and AuZnNi metallizations to n- and p-InP were studied as a function of the annealing temperature in a Rapid Thermal Annealing (RTA) system. For n-InP (S:8x10 18 cm -3 ) a broad minimum existed from 385°C to 500°C, in which the specific contact resistance, r c , was about 10 -7 ωcm 2 . The lowest value of 7x10 -8 ωcm 2 for n-InP occurred after RTA for 20 sec. at 450°C. For p-InP (Zn:5x10 18 cm -3 ) the lowest value of r c , 7x10 -6 ωcm 2 , was obtained for AuZn without any Ni. Metallurgical investigations indicated, that low r c values were associated with interfacial reactions and the formation of stable barrier-lowering metal-phosphides.
Access to an integrated services digital network is considered as a two-level problem in which users allocate circuit- and packet-switched traffic types within an assigned portion of a total available bandwidth. In a ...
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Access to an integrated services digital network is considered as a two-level problem in which users allocate circuit- and packet-switched traffic types within an assigned portion of a total available bandwidth. In a model suitable for a drop/insert integrated network, the users' bandwidth shares (capacities) are periodically reallocated by a centralized agent (in order to minimize a global cost function) on the basis of the observed overall system's state at the time of intervention. The gradient of the cost with respect to the local capacities is explicitly computed and used in applying a gradient projection algorithm to the central optimization problem.
A computer-aided design system for the kinematic and dynamic analysis as well as optimal design and synthesis of planar mechanisms based on component approach is presented. The AutoCAD program is used for the mechanis...
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A computer-aided design system for the kinematic and dynamic analysis as well as optimal design and synthesis of planar mechanisms based on component approach is presented. The AutoCAD program is used for the mechanism design environment. In this work, symbolic manipulation, communication interface, and graphics capabilities of the AutoLisp - a Lisp language interpreter within AutoCAD - is utilized for the design operations, mechanism definition and representation, and interfaces with the analysis and optimization programs. Except for the analysis and optimization routines, everything has been developed using AutoLisp language. The program runs on a micro-computer. Direct communication is developed between AutoCAD and the optimization as well as analysis packages using common data file format. Applications of the developed system to a number of illustrative examples are presented.
In this paper, the optimization of the spherical RRRR four-bar linkage for the problem of path generation is addressed. The problem is formulated as a two-loop minimization of the error between the path-generating poi...
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In this paper, the optimization of the spherical RRRR four-bar linkage for the problem of path generation is addressed. The problem is formulated as a two-loop minimization of the error between the path-generating point in the coupler curve and the prescribed position, while decoupling the linkage parameters from the configuration variables, namely, the input angles. The synthesis problem consists of evaluating a set of input angles {$PSIk}1m, defining m linkage configurations, and the linkage parameters independently. This leads to a constrained overdetermined system of nonlinear equations. The orthogonal decomposition algorithm, introduced elsewhere, is employed to solve the problem. Continuation and damping techniques are used in the numerical procedure to ensure convergence and speed up its rate. The optimization scheme is developed on a general basis and can handle the problem for any number of given path points. Two numerical examples are included.
Kinematic constraint-embedding procedures are presented for explicit dynamic modeling of general closed-chain systems in terms of a minimum coordinate set. These procedures are based on the use of internal kinematic i...
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Kinematic constraint-embedding procedures are presented for explicit dynamic modeling of general closed-chain systems in terms of a minimum coordinate set. These procedures are based on the use of internal kinematic influence coefficients(IKIC). The IKIC are higher order transformation matrices relating hypothetically open chain reference coordinates(system Lagragian coordinates) to a set of independent closed-chain coordinates(system generalized coordinates). These matrices, along with the principle of virtual work, allow for the determination of a system generalized coordinate based dynamic model in terms of the system Lagragian coordinate based dynamic model(s). Three different approaches for determining/evaluating the IKIC matrices, both symbolically and numerically, are investigated and discussed with respect to their relative computational merits.
The proceedings contain 37 papers. The special focus in this conference is on Astrodynamics. The topics include: Mission analysis for coincident measurements of m e upper atmosphere research satellite and space shulll...
The proceedings contain 37 papers. The special focus in this conference is on Astrodynamics. The topics include: Mission analysis for coincident measurements of m e upper atmosphere research satellite and space shullle experiments;launch window analysis for the CRRES mission;a system sizing and trajectory model for low -thrust OTV‖S;attitude and orbit control for GstAR i11 recovery mission;voyager 2 Neptune navigation results;voyager 2 Neptune navigation results;voyager 2 Neptune navigation results;optical navigation during the voyager Neptune encounter;performance of three-way data types during voyager‖s encounter with Neptune;voyager 2 orbit determination at Neptune;the near real time image navigation of pictures returned by voyager 2 at Neptune;ephemerides of the major neptunian satellites determined from earth-based astrometric and voyager imaging observations;universal Lambert and kepler algorithms for autonomous rendezvous;untruncated perturbation analysis for a satellite orbiting in a non-rotating gravitational field;a perturbation solution for all orbital parameters;series inversion of Lambert's time function;stable orbits about phobos and diemos;the lunar observer mission;21st century early mission concepts for mars delivery and earth return;mars parking orbit selection;Saturn orbit insertion mission plan for Cassini;deep atmospheric probe missions to Uranus and Neptune;radiation force modeling for the topex spacecraft;examples of the nonlinear dynamics of ballistic capture and escape in the earth-moon system;modeling and analysis of orbiting tethers in an atmosphere and the perturbation of ground tracks of periodic orbits.
A method for efficiently analyzing distributed power systems during the design process is presented. Individual DC-DC power converters are modeled by using averaged or device-level representations. The averaged models...
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A method for efficiently analyzing distributed power systems during the design process is presented. Individual DC-DC power converters are modeled by using averaged or device-level representations. The averaged models for basic power converter topologies are combined with behavioral models for the control loop. Simulation accuracies close to those for a full component-level model can be achieved with more than an order-of-magnitude reduction of the simulation time. The newly developed models are used for system-level simulation. systemstability for fully distributed loads is readily determined for a number of power systems configurations.< >
A systematic approach to the formulation of continuous-time dynamic equations for switching power converters is presented. A new modeling formalism for semiconductor switches is developed as part of this approach. The...
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A systematic approach to the formulation of continuous-time dynamic equations for switching power converters is presented. A new modeling formalism for semiconductor switches is developed as part of this approach. The general structure of the equations is investigated, and, based on a geometric interpretation of the equations, a classification scheme is proposed. Nonlinear methods for analysis and control appropriate to each class are examined. A comparison of current mode and voltage mode DC-DC power converter control is presented as an example.< >
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