Discussed in this paper is a novel method for the generation of Jacobian matrices which is particularly suitable for object-oriented implementations of multibody dynamics programs. The method starts from a description...
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Discussed in this paper is a novel method for the generation of Jacobian matrices which is particularly suitable for object-oriented implementations of multibody dynamics programs. The method starts from a description of multibody kinematics as a series of general mappings between manifolds, from which the overall Jacobian results-via the chain rule-as a sequence of matrix products. For these matrices, a new sparse-matrix scheme is suggested. Their "elements" are, besides zeroes, the well-known spatial transformation matrices and the local Jacobians of the individual transmission elements. It is shown how the main approaches for calculation of Jacobians in robotics can be viewed as particular decompositions and multiplication schemes of the sparse-matrices discussed above. Furthermore, two new schemes are derived which may be advantageous for dynamics calculations. The exposition is complemented by a comparison of Jacobian-based methods with composite rigid body and recursive methods for the generation of dynamical equations together with some comments on our current C++-implementation.
In this paper we present an approach to integrating optimisation tools with simulation software to achieve user-defined objectives. A formal protocol is presented, including specific definitions of the requirements of...
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In this paper we present an approach to integrating optimisation tools with simulation software to achieve user-defined objectives. A formal protocol is presented, including specific definitions of the requirements of the simulator, optimiser, and design interface. A discussion of the mathematical issues and the efficiency of different approaches for computing sensitivities is given. We then discuss the source code modifications necessary to accomplish the integration of simulation and optimisation. (C) 1996 by Elsevier Science Inc.
Test data are an invaluable resource for structural engineering research. In this paper, a numerical database system is built for material properties of steels, steel columns, steel beams and unstiffened steel plates,...
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Test data are an invaluable resource for structural engineering research. In this paper, a numerical database system is built for material properties of steels, steel columns, steel beams and unstiffened steel plates, etc. The database is used to clarify the strength variations of material properties and to obtain the mean value and the coefficient of variation of each member strength. In addition, these values are compared with existing design formulas. The database is further developed in the shape of a structural test information-based system. This system includes database functions, test data evaluation functions, reference retrieval functions and technical terms explanation functions. The usefulness of the knowledge base approach for representing the test data is proved and the potential and problems of the system are clarified. Copyright (C) 1996 Elsevier Science Ltd.
The efficiency of object-oriented programs has become a point of great interest, One necessary factor for program efficiency is the optimization techniques involved. This paper presents the performance of several vari...
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The efficiency of object-oriented programs has become a point of great interest, One necessary factor for program efficiency is the optimization techniques involved. This paper presents the performance of several variations of a given C++ program and compares them with a version that uses no object-oriented features, Our result indicates that some object-oriented features in C++ are not well optimized in current C++ compilers. We thus discuss some code optimization techniques that can improve the efficiency based on the given C++ program.
DESC++ (Discrete Event Simulation package using C++) has been developed as an object-oriented tool for quantitative simulation studies of communication protocols and architectures of telecommunication networks. The ma...
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DESC++ (Discrete Event Simulation package using C++) has been developed as an object-oriented tool for quantitative simulation studies of communication protocols and architectures of telecommunication networks. The main issue of such performance studies is to secure proper statistical accuracy of the final simulation results. In DESC++ this problem has been solved by automating analysis of simulation output data, aimed at stopping simulation when the estimates reach the required level of precision. The package consists of various object classes. While some of them are responsible for on-line output data analysis, others allow simulation programs of telecommunication networks to be easily developed by re-using existing (sub)models. We discuss main design and implementational issues of DESC++, and illustrate them by an example. Copyright (C) 1996 Elsevier Science Ltd
One of the most intriguing-and at the same time most problematic-notions in object-oriented programming is inheritance. Inheritance is commonly regarded as the feature that distinguishes object-oriented programming fr...
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One of the most intriguing-and at the same time most problematic-notions in object-oriented programming is inheritance. Inheritance is commonly regarded as the feature that distinguishes object-oriented programming from other modern programming paradigms, but researchers rarely agree on its meaning and usage. Yet inheritance is often hailed as a solution to many problems hampering software development, and many of the alleged benefits of object-oriented programming, such as improved conceptual modeling and reusability, are largely credited to it. This article aims at a comprehensive understanding of inheritance, examining its usage, surveying its varieties, and presenting a simple taxonomy of mechanisms that can be seen as underlying different inheritance models.
A good layout design is important for a cellular manufacturing system (CMS) to operate efficiently. Traditional algorithms for layout design are confining and have limitations with regard to decision factors and knowl...
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A good layout design is important for a cellular manufacturing system (CMS) to operate efficiently. Traditional algorithms for layout design are confining and have limitations with regard to decision factors and knowledge representation. Knowledge-based expert systems have opened up a new way for modelling and evaluation of the ill-structured CMS layout problem. In addition to the advantages of integrating the vast amount of available knowledge and making it accessible to ordinary users, the knowledge-based approach is also useful for dealing with ambiguous, qualitative information and empirical knowledge that are often part of the CMS layout design process. The objective of this research is to develop a prototype for CMS LAyout Design Expert System (CLADES) by using the expert system shell KEE (Knowledge Engineering Environment). This expert system would provide a powerful and efficient decision support tool for users in CMS layout design. CLADES solves the CMS layout problem in two stages. In the first stage, the machine cell layout is determined. In the second stage, the machine layout within each cell is determined. To obtain a reasonable layout design for a CMS, several factors which affect the decision are used as criteria in the CMS layout design problem. They are production quantity of the system, variation of part process routing, material handling system, unit load of an item, and dimensions of the floor plan. The design options considered by CLADES include three types of layout for machine cells, four types of layout for machines within a cell, and five types of material handling systems. In its current form, CLADES contains 58 rules, three models and three algorithms, and one algorithm is directly coded in CLADES in the LISP language. CLADES uses a tandem architecture, which connects the knowledge base to the model and algorithm base. This structure takes advantage of not only the expert system approach, but also the optimization approach. CLADES is code
An object-oriented data model for the elaboration of scanning probe microscopy information is proposed. This data model provides a comfortable interoperability between different types of data, presented as visual obje...
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An object-oriented data model for the elaboration of scanning probe microscopy information is proposed. This data model provides a comfortable interoperability between different types of data, presented as visual objects. On the other hand, this model correlates with modern compound document programming technology, and can be implemented within a client-server application, exploiting the benefits of distributed data systems. Such a data model is suitable for scanning probe microscopy image processing, and could be useful for some other research fields, allowing the integration of a huge amount of composite data.
In this paper, the bill of materials (BOM) system is defined as the central hub of a general product data management (PDM) system that provides essential data for running a manufacturing system to produce products. In...
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In this paper, the bill of materials (BOM) system is defined as the central hub of a general product data management (PDM) system that provides essential data for running a manufacturing system to produce products. Information that is relevant to products and their components is defined in the BOM. The information is critically related to data from product design, manufacturing planning, production management, procurement, inventory control, and accounting within a company. A conventional BOM structure (or product configuration), which manages data only in a stand-alone relational database management style, cannot satisfy the needs requested by all departments within a company. A BOM should relate to and communicate with other domains of the information system. In this research, a newly designed BOM system uses the object-oriented programming (OOP) concept to represent product information. The object-oriented BOM (OOBOM) system can capture and encapsulate data that will simultaneously serve the information needs of various departments. In order to manage product data dynamically, the system provides several interfaces for easy data access and manipulation. The linkage between BOM and its corresponding CAD/CAM system is enabled through the X-window manager: thus an integrated PDM environment is developed. This product management approach improves the consistency and efficiency of product data representation.
作者：
Thiery, RCREGU
BP 23 F-54501 Vandoeuvre-lès-Nancy Cedex France
A new global approach for calculating thermodynamic properties of fluids with equations of state is proposed. This method uses an object-oriented library, written in C++, and containing a number of routines that facil...
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A new global approach for calculating thermodynamic properties of fluids with equations of state is proposed. This method uses an object-oriented library, written in C++, and containing a number of routines that facilitate thermodynamic calculations. It is applicable to any equation of state formulated by an analytical expression of the Helmholtz free energy. The programming work of the user is limited to the building of a parse representation of the Helmholtz free energy. This parse graph is then processed by the program for analytically calculating the required derivatives and thermodynamic properties of fluids. A demonstration of this library is made with the Anderko and Fitter equation of state for H2O-NaCl-KCl fluids. The Helmholtz free energy has been differentiated analytically up to the fourth order with respect to the temperature, molar volume, and composition. Calculated derivatives are used to calculate the critical line of H2O-NaCl mixtures and other thermodynamic properties, which otherwise would be difficult to obtain. Copyright (C) 1996 Elsevier Science Ltd
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