摘要:

Abstract:A new fuzzy control method for the reduction of the dynamic response of structures is presented, and is compared with the instantaneous optimal control method. The control forces are determined from preformulated fuzzy rules regarding the velocity and the acceleration of the system. The triangular membership function and the mini‐max‐gravity method are used in the fuzzyfication and the defuzzyfication process, respectively. In these processes, no material property of the structure such as the mass matrix or the stiffness matrix are needed. This characteristic nature is definitely different from that of optimal control algorithms. Numerical examples are shown in order to compare the performances both of the proposed fuzzy control method and the optimal control method. It appeared that the fuzzy control method is quite useful as regards reliability and robustn

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00429.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper treats a basic study on a methodology of large reduction of the huge stiffness matrix equation with many unknowns for application on very high speed supercomputer or connection machines. Until recently the substructured method according to the Neumann‐type single processing has been used for the above purpose, whereas the method described here differs from its predecessor as pertaining to non‐Neumann‐type plural processing by the system of multilinked computers. The characteristics of the method exist in an algebraic and mechanical idea for the very large structural matrix equation, to make it constitute a properly decided number of independently blocked‐in submatrix equations so as to be able to utilize the supercomputer or connection machines in the most eficient way. For this purpose, the method presented in this paper shows how to relocate and add rows and columns in the original structural stiffness matrix equation, taking the effective stiffnesses of intersected boundary members into proper consideration. Next, this method is applied to a simple rectangular frame as the first step, this time to consider and verifv its adequacy. Finally, some remarks are made on the comparative state between analytical results by this parallel processing for substructured matrices on it, and by the usual direct processing for its original matrix. It is concluded that the method presented here may be thought suficiently appropriate and useful for the

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00430.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:A general‐purpose, rigorous and efficient optimum design system for steel cable‐stayed bridges is developed, in which not only can the cable anchor positions on the main girder and pylon, and the crosssectional dimensions of the member elements be dealt with as design variables, but also the pseudo‐loads applied to the cables. A powerful two‐stage optimum design method is proposed to determine the optimum values of design variables for the cost minimization problem under stress constraints. At the first‐stage optimization process, the cable arrangement and sizing variables are optimized by using the approximate concept and dual method with mixed direct/inverse design variables. Then the optimum values of pseudoloads, which induce the optimum prestresses into the cables, and the optimum sizing variables are determined so as to minimize the total cost of the bridge further by utilizing the sensitivities with respect to the pseudo‐loads and a modified linear programming algorithm. The rigorousness, eficiency and practical usefulness of the proposed optimum design system are demonstrated by giving numerical design examples and the investigations of the optimum solutions at various design conditions. The significances of dealing with cable anchor positions and pseudo‐loads as design variables are al

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00431.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Debugging of the input data of a structural analysis program is a troublesome task which is heavily dependent on empirical knowledge. The paper describes an effort that applies machine learning to build an expert system for debugging faults in structural analysis program input data. ID3 decision tree induction algorithm is employed to build the automatic learning mechanism. This method Oflkrs an attractive potential for knowledge acquisition in the civil engineering domain in which expertise plays a dominant role. This paper is novel in at least three aspects: (1) machine learning is employed to build expert systems automatically; (2) a novel impurity function is proposed for splitting the decision tree; (3) a formulated comparison is proposed for evaluating learning results.

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00432.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:An algorithm is proposed for the generation of ‘hybrid’ finite element meshes composed of quadrilateral and triangular elements over any arbitrary planar domain. Although more complicated hybrid meshes are to be generated, the new meshing strategy does not require more input data than a correct representation of the domain boundary. Mesh generation is started by constructing as many square elements as possible in the interior part of the domain, leaving a relatively small region around the boundary which is to be tliscretized into triangular elements by standard triangulation procedures. As a result, only the quality of the triangular elements near the boundary will be affected by the irregularity of the domain. The extraction of the interior part and forming of square elements of an irregular domain will be discussed in detail. Examples of meshes generated over simply connected and multiconnected domains are gi

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00433.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Irrigated farming is a complex activity influenced by a large number of interacting and random factors. A sufficiently realistic gaming simulation model can be used as an effective tool for training in decision making under such a setting. This paper describes a microcomputer‐based game model CASIMBOL (Computer Aided Simulation of Irrigation Management Below OutLet) that deals with the problems faced by a typical farmer in a water‐deficient region in southern India. The model is built in a spreadsheet environment. Menu‐driven macros are developed for automating the gaming session, with provision for selective revision of random variable values. A case‐specific synthetic knowledge base is made available for consultation at selected stages during the progress of the game. The advantages, limitations and further possibilities of this model have been brought out during trial sessions involving academic and field personnel. The spreadsheet‐based game model linked to a mini expert system demonstrates that this methodology can be adopted for similar s

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00434.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Non‐classical fractals generated by many generators are of interest. Random fractals caused by the random action of given generators and by random generrrtors are discussed The generators may have different scales. The fractal spectral function, the generalized fractal dimensions and scaling index are derived explicitly. Examples include the cracking patterns of concrete mi

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00435.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY