摘要:

The main purpose of this paper is to develop a node‐to‐cubic‐spline contact element for frictional contact problems. For node‐to‐line contact algorithms, the normal and tangent directions of contact stresses are usually discontinuous across two elements. This drawback sometimes causes inaccuracy of the contact analysis near the intersection point of the two target surfaces, or sometimes causes the divergence of the contact analysis when a contact node moves across two target surfaces. Moreover, if the mesh of the target surface is not fine enough, using node‐to‐line contact elements to model curved surfaces will cause errors. In order to overcome this drawback, a two‐dimensional node‐to‐cubic‐spline contact element is developed. Each element contains one contact node and a number of target nodes modeled by a cubic spline with continuous normal and tangent directions. A contact node can slide across several target lines with not only the compatible deformation but also the continuous normal and tangent directions. Numerical results demonstrate that the present cubic‐spline contact element can simulate contact problems accurately even using a coarse mesh of the target body.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670377

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The effects of electromagnetic interference (EMI) coupled through the substrate, gate input, and power supply into MOS devices are studied experimentally. This research also investigated the performance degradation of nMOSFET, pMOSFET, and CMOS inverters due to interference. Their bias dependence, RF power, and frequency dependence are taken into account. Furthermore, empirical models are proposed to predict EMI susceptibility. Predicted results compare well with experimental data.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670378

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A control law that keeps a closed‐loop system asymptotically stable against arbitrary sensor failures is proposed. Systems which have such a property are said to possess integrity, and this is an inherent property of MIMO systems. The synthesis method of the linear state feedback controller and the associated upper bound for tolerable perturbations are derived utilizing the properties of the spectral radius and matrix inequalities. Compared with existing integrity design approaches, the computation load for solving the tedious matrix Lyapunov or Riccati‐type equation is reduced. In addition, this design approach is further extended to an uncertain system and to retain the stability characteristics of the given open loop system. In both cases, tolerable perturbation bounds are all expressed explicitly such that the closed‐loop system still possesses integrity. The simplicity and effectiveness of this method are demonstrated with two numerical examples.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670379

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A continuous‐time Markov chain model, which considers the concept of human errors and recovery factors, is proposed for analyzing the reliability of a man‐machine system. The model can be applied to general systems which involve man‐machine interactions. Both the reliability and the mean time between breakdowns of a system can be predicted by using this model. An inspection system, a conveyer line system, a cellular manufacturing system, and an automatic assembly machine are used to demonstrate the application of the reliability model. During the design stage of a man‐machine system, the model can provide reliability evaluation information to aid in the choice of different alternatives for man‐machine interaction. During the operating stage of a system, the model can also provide reliability information to improve system reliability.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670380

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The viscoelastic behaviors of simply‐supported, cross‐ply laminates with a physical aging phenomenon are examined. The laminates considered are under uniaxial in‐plane compression and have various amplitudes of initial imperfection. Laminae exhibit different aging shift rates for the creep responses to the axial and shear loadings. The effective time theory is employed to construct the stress‐strain relations. The stress function is obtained by solving the compatibility equation by the use of the Laplace transform and a numerical integration scheme. Deflections are calculated from the moment equation by the Galerkin method in conjunction with the numerical integration. Numerical results of creep deflections, edge shortenings and stress resultants for graphite‐reinforced thermoplastic and glass‐reinforced thermosetting laminates are presented. The effects of physical aging, pre‐loading aging time, and the amplitude of imperfection on the creep responses are illustrated in the numerical examples.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670381

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The synthesis of 2‐mercaptobenzimidazole (MBI) from the reaction of carbon disulfide and o‐phenylene diamine (C6H4(NH2)2), catalyzed by tetrabutylammonium bromide (TBAB or QBr) in the presence of potassium hydroxide, was carried out in a homogeneous solution using protic or aprotic solvent. Water in a small amount was added to dissolve the KOH. The role of KOH in the reaction was investigated by conducting several independent experiments, which included a timed reaction of CS2and KOH, and further reaction of C6H4(NH2)2in the presence or absence of TBAB catalyst in various sequential orders. A homogeneous reaction mechanism was proposed which supports the kinetic reaction model. The reactions were situated in protic and aprotic solvent and are described by zero‐order and pseudo‐first‐order rate laws, respectively. The effect of the amount of KOH on the conversion of C6H4(NH2)2was also studied. The reaction was greatly accelerated both in the presence of TBAB catalyst and KOH. Satisfactory explanations were provided for the enhanced catalytic reaction of CS2and C6H4(NH2)2by TBAB compared with KOH. The reaction rates in these processes are also discussed in detail.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670382

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Undercutting and pointing are serious problems in the performance of face‐gears. Based on the theory of gearing, the tooth geometry of the face‐gear along with the sufficient and necessary conditions for the existence and regularity of the generated face‐gear tooth surfaces were investigated. Undercutting and pointing were initially investigated by Litvin. In this paper, numerical results with design charts for avoiding undercutting and pointing of the shaper and generated face‐gear were further developed. The boundary lines of undercutting and pointing for a number of face‐gears under different tooth numbers, modules and pressure angles were established.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670383

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper considers a single machine scheduling problem with fuzzy due date and fuzzy processing time. There arenjobsJ1,J2, …, Jnto be processed on a single machine. Associated with each jobJj, there is a membership function of due date which describes the degree of satisfaction with respect to the completion time ofJj. The due date is structured similar to a trapezoidal fuzzy set, and the processing time is described as a triangular fuzzy set. The objective is to maximize the minimum grade of satisfaction over given jobs. In this paper, polynomial‐time algorithms withO(n2logG) are proposed to solve the scheduling problem and are illustrated by means of an example.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670384

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this study, a non‐staggered PACE (Pressure Accurate Continuity Exact) algorithm for the solution of incompressible Navier‐Stokes equations is proposed. Time accurate solutions are obtained at each time step using consistent, multi‐step iterations of pressure solution and velocity corrections. From the computation of a square cavity flow with different Reynolds numbers, it was found that the proposed non‐staggered PACE algorithm consumes less computer memory and CPU time, has a smoother rate of convergence, and can predict incompressible flows as accurately as a well‐established staggered SIMPLER algorithm. A non‐staggered grid algorithm is easier to implement and is more favorable as body‐fitted or three‐dimensional computations are required.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670385

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper considers the performance robustness analysis problem of uncertain linear systems with output feedback. When there are uncertain parameters in all matrices of the state‐space model of the controlled system, a bound on these parameters is found such that theH8norm performance index of the closed‐loop system is kept below a prespecified value. The proposed analysis method is based on the matrix nonsingularity robustness analysis approach and several algebraic conditions about theH8norm. It is shown that the bound can be computed from structured singular values of certain composite matrices. An example is provided to illustrate the results.

ISSN:0253-3839    

DOI:10.1080/02533839.1998.9670386

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor