摘要:

Abstract:A relatively general formulation for studying the dynamics of a large Class of seacecraft characterized by interconnected flexible memebers forming a tree topology is presented. Extremely lengthy, hightly nonlinear, nonautonomous, and coupled equations of motion are amenable only to numerical solution using a high performacnce computer. Discretization of the continuum system is accopolished through either component or system modes obtained through a finite element analysis. Its evolving Space Station Freedom. The modal spectra suggest that: (i) the appendage flexibility plays an important role in governing the system dynamics: (ii) close spacing of the frequencies with possible overlap will make the response extremely complex and the control equally challenging; (iii) the system modes are siginificantly influenced by the growth of the main truss and module clusters. versatility of the general formulation is demonstrared systems: the permanently manned configuration (PMC) of the Space Station: and a system similar to the space flyer unit (SFU) under development in Japan. The PMC study shows that even a small main truss disturbance can excite not only large amplitude motion of the appendages, but also truss velocity and acceleration levels exceeding the specified limit. The deployment of the solar array pedal (SAP) of the SFU shows that the spacecraft remains stable under both symmetric and asymmetric deployments. Advantage of out‐of‐plane symmetric retrieval is found to be stable: the in‐plane retrieval induces unsatisfactory librational motion. For an asymmetric retrieval, the spacecrat response is untable and an active control would be req

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00421.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper describes a classflcation learning system and its application. A PDP learning program (parallel distributed processing, or neural nets) learns from sample data and makes predictions for new cases. This inductive inference is capable of dealing with messy, real world data in architectural design. The authors report on experiments in which the PDP model was used to synthesis design generative rules for certain aspects of the spatial configuration of Japanese tea houses. The possibility of the PDP model as a design descriptive framework is explored.

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00422.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper describes some of the results of the authors' research on autonomous construction robotics. The objective of our research is to find out whether autonomous construction robots are feasible or not, and how autonomous construction robotics might be achieved. The paper presents the information technologies required and an initial (simulated) example of an autonomous tiling robot.

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00423.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:In the critical analysis of fracture and unstable behavior of structures, the uniqueness of solution is no longer assured. Such critical states can be analyzed by recognizing their deformation‐ and forcespaces which are not considered in the usual numerical matrix analysis. The purpose of this paper is to show the applicability of qualitative reasoning, which has been recently developed as a method of artificial intelligence, to the above‐mentioned critical analysis of structures. To recognize multi‐dimensional spaces, qualitative reasoning is performed using reasoning rules described with production rules ‘if ∼ then ∼’ and qualitative values +, 0 and −. As a case study, qualitative reasoning is applied to some kind of truss units subjected to combined axial force, bending moment and shear force. Its mechanical behavior can be illustrated in the three‐dimensional deformation‐ and force‐spaces. Here, the LISP language, which is suitable for processi

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00424.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper presents an elementary approach to artificial intelligence in structural engineering with the aid of the scheme of geometric modeling in computeraided design. In order to generate a specific form feature the structural shape information is explicitly represented, using a frame language developed in Prolog. Thus, reasoning stableness of structures in this system are interpreted as a sequential instantiation of a frame structure in which attributes stand for topological data and procedural knowledge, and as a candidate generation of a substructure of the stable form. Illustrative examples for a plane truss structure are described. Also, some comments on its applicability to an intelligent tutoring system for structural analysis and architectural design are provided, with reference to the interactive graphic representation.

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00425.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:A system for simulating the behavior of a reinforced concrete building being demolished by controlled explosion is developed. The purpose for developing the system is to examine the effects of blast location, blast size, blast sequence, delay time of blasts and other factors on a planning of blast demolition. It consists of a numerical analysis part to simulate the blast demolition of a space‐framed structure and a visualizing system to show the dynamic behavior obtained from the numerical analysis. The numerical analysis is based on the distinct element method, which is improved for consideration of the bending behavior of beams and columns. The elastoplastic behavior of the structural members up to the collapse are modeled in the analysis. The numerical data display system ‘AVS’ is employed, in addition to the computer code developed by the authors, to make the visualization system for three‐dimensional dynamic problems. In this report the method of numerical analysis, the visualizing system, and a comparison between the experiment and analysis are pr

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00426.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:A local database manager (LDBM) is presented. It is a software development tool consisting of a set of easy‐to‐use in‐core data management subroutines written in FORTRAN 77. One of the main motivations for the development of this LDBM was to enhance the eflcient use of core memory which seems to be obvious with respect to a PC programming environment. However, even on virtual machines, high performance achieved by minimizing page faults is strongly based on a sophisticated database management system (DBMS). In order to accomplish this objective, the LDBM allows the use of different data types according to the requirements of the actual situation and to the existing programming environment. Integer, short integer, real, double precision, complex, double complex and character data can be handled. Moreover, a two‐level hierarchical data structure is used which groups related data in a different and more economic way rather than by means of increasing the number of levels in the DIMENSION statement. Of course, old, no longer used data may be deleted, leaving room for the allocation of new data. Using a technique of ‘flexible garbage collection’, i.e. the ensuing gap after the deletion of a data block is not automatically closed, the time consumed by the LDBM during a deletion operation is actually not affected by the length of

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00427.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00428.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY