ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677266

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Connection through a single bus is the simplest architecture for multiprocessor systems. However, as the number of processors scales up, the common bus will eventually become the bottleneck of the system. Three different bus‐based architectures, multiprocessors without local memories, multiprocessors with single port local memories, and multiprocessors with dual port memories, are analyzed in this paper. It shows to what degree increasing the local execution probability of a multiprocessor system with dual port memories can relieve the load of the common bus and thus increase the effective computing power. A multiprocessor operating system (MOS) designed at National Chiao Tung University (NCTU) has suffered bottleneck trouble in the previous year. Problems in MOS are discussed. A new design of this operating system kernel, MOS*, is then proposed. Performance of these two different designs are evaluated and compared by simulation. The simulation results show that MOS*, with a localizing process strategy, can increase effective computing power 30–100 percent. The saturation point of MOS* is also explored in the paper.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677267

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Numerical solution of the nonlinear non‐resonant interaction between two trains of gravity waves in a finite water depth is studied in this paper. Two finite Fourier series with unknown coefficients are assumed for the velocity potential and the free surface elevation. The unknown coefficients are then determined numerically by a linear Taylor differential correction technique applied iteratively to minimize the free surface boundary condition error. Numerical results up to the fifth‐order are calculated for short‐crested waves, oblique incident waves partially reflected on a vertical seawall, and two interacting wave trains of arbitrary wave numbers and directions.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677268

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A finite‐difference solution is developed to study the two‐dimensional flowfields of a combustion chamber. The methodology is also applied to the steady in‐cylinder flows, where the boundary of the cylinder head is a curved wall. The curved wall is described by a cubic spline interpolation function. The governing equations are expressed in axisymmetric nonorthogonal curvilinear coordinates. A rectangular computational domain is yielded by Moretti's transformation and the task of numerically generating the body‐fitted coordinates is avoided. Hence, the matrix of the coordinate transformation can be determined by direct analytic differentiation. The discretized conservation equations are derived on a control volume basis and solved by the extended SIMPLE calculation procedure. The program is run on an IBM PC/AT. Numerical results obtained by employing the present methodology are compared with results from an analytical solution. The relative merits of three numerical representations, i.e., power‐law, hybrid and first‐order upwind, for approximating the convection terms in the momentum equations are compared. The application of the methodology is illustrated using steady in‐cylinder flows. The effects of inlet Reynolds number on the velocity distribution are also investigated.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677269

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Evaluation of point defect equilibria in Hg0.8Cd0.2Te and Hg0.6Cd0.4Te using the Gibbs free energy minimization approach is demonstrated in this paper. Appropriate standard Gibbs free energies of formation for doubly charged mercury vacancy, mercury interstitial, electron and hole were derived. Thep‐ntransition behavior in Hg0.8Cd0.2Te and Hg0.6Cd0.4Te with intrinsic defects and/or residual impurity donors was also calculated and compared favorably with experimental data from literature.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677270

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

According to the theory of algebra, this paper confirms that the Mejia and Rousselle model employing the conventional parameter estimation procedure fails to preserve the historical moments as anticipated. The cause of the failure is identified. For each stage of disaggregation, two corrected moment estimates for use in parameter estimation are proposed. The first estimate is derived based on making the parameter estimation equations mathematically consistent; the second estimate, on maintaining the linear relationship between the disaggregated flows and the flows being disaggregated. Using the proposed, corrected parameter estimation procedure, the moments of interest and additivity are preserved exactly in an expected value sense. Applications given also show that the proposed procedure has advantages over the conventional procedure.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677271

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An analytical approach to the description of the radial bed topographies in a steady state, fully developed alluvial channel bend with uniform bed material with different sediment concentrations is presented. The approach is based on the conservation of moment of momentum and the modified velocity profile due to sediment suspension. Bed topography simulation is verified by laboratory data. Sensitivity analyses were also performed to study the effects of sediment concentration on transverse bed profiles.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677272

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

To improve the damping of a multimachine power system, a static VAR compensator (SVC) equipped with a supplementary feedback controller is proposed. In the design of the supplementary feedback controller, a fixed‐gain proportional‐integral (PI) controller is first investigated. To further improve system dynamic performance, two types of adaptive controllers, i.e., pole‐shifting self‐tuning controllers and self‐tuning PID controllers are developed. The effectiveness of the presented adaptive control schemes is demonstrated by time domain simulation of the multimachine system subject to a three‐phase fault. It is found that both self‐tuning controllers can yield much better dynamic responses than the fixed‐gain feedback controllers under disturbance conditions.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677273

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The mass‐transfer phenomenon between an aqueous‐organic phase and an electrode producing sulfur from sulfide ions in a parallel plate reactor is studied. A kinetic model of the electrochemical conversion and extraction process is developed and tested. Under steady‐state conditions, the electrochemical reaction rate at limiting operation, defined asK‘mA(1 –θ)CR/α,is equal to the extraction rate, defined asK‘dA θ(Csats/β‐ Cs/β) for this extractive electrochemical system. Experimental parameters include volume fraction (Xd) and fluid velocity (Re‘). The mass transfer coefficients,K‘mandK‘d,were obtained asK‘m=7.044 × 100–5Re‘?(1.073 + 0.575Xd– X2d) andK‘d= 5.15 × 10–4Re‘?Xdwith a Reynolds number between 18∼54 and volume fraction under 70% for this two‐phase solution.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677274

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This study examines the temperature distributions of steel frames exposed to a prescribed fire environment. The effects of radiation, natural convection, and heat conduction are fully considered in formulating the mathematical model. The method of orthogonal collocation and the variable order Adams predictor corrector method are adopted for the numerical solution.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677275

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor