ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677253

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Thermodegradation of poly[3‐dimethyl(acryloyloxyethyl)am‐monium propanesulfonate], [poly(DAAPS)], was investigated under nitrogen and air atmospheres at various heating rates. When calculating kinetic parameters, such as the activation energy, the preexponential factor and the reaction order, Ozawa's method was applied. Thermodegradation of such polymers occurs in two stages in a nitrogen atmosphere and in three stages in air. These phenomena were the same as with poly(DMAPS).

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677254

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

In this paper, anisotropic wave propagation theory was utilized to measure the slight anisotropy of a cold‐rolled aluminum plate. To reveal the slight anisotropy (texture) in such a medium, the deviation of the energy and phase velocity was taken into account. A numerical algorithm was developed to calculate the phase velocity from the measured energy velocity, and hence, to determine the elastic constant matrix of the cold‐rolled aluminum plate. It is found, from the measurements, that the rolled aluminum plate preserves slight transverse isotropy with the axis of symmetry along the rolling direction. The Young's modulus along the rolling direction is slightly smaller than those along the other two directions.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677255

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Cold unidirectional compaction of smaller‐sized rapidly‐solidified (RS) and larger‐sized non‐rapidly‐solidified (N‐RS) aluminum alloy powders has been studied. The particle packing, plastic flow and interparticle bonding of the compacts were examined in detail. The pressure‐density‐strength (PDS) relationships of the compacts of RS and N‐RS powders were investigated, compared and discussed. Special effort was made to investigate the particle size fraction effect on the P/D/S relationships of N‐RS powder compacts.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677256

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Both experimental and analytical methods were employed to evaluate the residual strength and residual stiffness of reinforced concrete columns after different durations of fire. Twenty‐five columns were first exposed to fire and then tested under concentric axial loads or eccentric axial loads. The results were compared with those obtained from the analytical method. The comparison showed that the analytical appraoch is acceptable. It also indicated that fire duration and section size and amount of significantly affect the degree of deterioration of strength and stiffness of columns. The proposed stress‐strain curve for concrete after fire in this study was proven to be reasonable.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677257

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The stability behavior of pipelines on the ground surface or buried in relatively shallow trenches is studied by using the model of beam mode buckling. We model the pipelines as infinitely long, localized large deflection, and elastic‐plastic beams on elastic half space. The finite element method, boundary element method, and finite difference method are employed for the numerical solution.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677258

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This study discusses the state of the flow field and the diffusion of concentration under the interaction of a stream debounchment and sea currents at a river mouth. Three‐dimensional unsteady conservation equations are used to describe the interaction of the flow field. The dynamic factors considered include the effects of buoyancy, inertia, hydrostatic pressure and mixing turbulence. Turbulence effects are modeled using an eddy viscosity through the Reynold Approximation. For convenience in calculation the coordinate system transform is used, combining the horizontal stretching transform and the sigma‐coordinate transform.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677259

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper presents a new boundary element formulation in which the eigenvalue appears outside the integral operator, which distinguishes it from the Helmholtz integral equation. Thus, the formation of global matrices need only be assembled once. Since the kernel of the operator used in the new formulation is real‐valued, all calculations can be carried out in a much simpler way in the real domain. The complex acoustic pressure amplitude is considered herein to deivate by a certain amount from a harmonic function. It is an important contribution that an exact relation between the deviator and the complex acoustic pressure amplitude is constructed locally and thus no more approximations are introduced except conventional boundary discretizations. Several examples are given to illustrate the feasibility of an accurate, effective prediction of resonance.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677260

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

This paper presents both state space and frequency domain approaches for the decentralized decoupling of multivariable control systems with unmodelled interaction. The controller has a configuration of two degrees of freedom. Thenominal controlleris tuned to satisfy the eigenvalue specification of the isolated single variable subsystem. The rejection of unmodelled coupling due to the connections or disconnections of other subsystems is controlled by thedecentralized compensator.The method assumes that only local information is acquirable, no information from other subsystems and no interconnection parameters are required. This gives the convenience of single variable design for multi‐variable control applications. The decentralized compensator can also be used to improve the performance of the control system with unmodelled nonlinearity or parameter drifting. The stability of the control system with the decentralized compensator has been investigated. Two numerical examples are given to show the feasibility of the method.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677261

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The purpose of this work is to develop a mathematical model that describes the steady state behavior of a pusher type slab reheating furnace, and to compare the calculated results with experimental results found from literature. Numerical solutions for a 3‐zone pusher type heating furnace were obtained and the results agree closely with experimental values obtained by other investigators. It has been found that the size of the subzones can not be too large, otherwise significant deviations between calculated and experimental results will occur. Close agreement between calculated and experimental results justifies the validity of the model developed in this work.

ISSN:0253-3839    

DOI:10.1080/02533839.1990.9677262

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor