The new Reference Resistance Design (RRD) method, recently developed by Rotter [1], for the manual dimensioning of metal shell structures effectively permits an analyst working with only a calculator or spreadsheet to...
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The new Reference Resistance Design (RRD) method, recently developed by Rotter [1], for the manual dimensioning of metal shell structures effectively permits an analyst working with only a calculator or spreadsheet to take full advantage of the realism and accuracy of an advanced nonlinear finite element (FE) calculation. The method achieves this by reformulating the outcomes of a vast programme of parametric FE calculations in terms of six algebraic parameters and two resistances, each representing a physical aspect of the shell's behaviour. The formidable challenge now is to establish these parameters and resistances for the most important shell geometries and load cases. The systems that have received by far the most research attention for RRD are that of a cylindrical shell under uniform axial compression and uniform bending. Their partial algebraic characterisations required thousands of finite element calculations to be performed across a four-dimensional parameter hyperspace (i.e. length, radius to thickness ratio, imperfection amplitude, linear strain hardening modulus). Handling so many nonlinear finite element models is time-consuming and the quantities of data generated can be overwhelming. This paper illustrates a computational strategy to deal with both issues that may help researchers establish sets of RRD parameters for other important shell systems with greater confidence and accuracy. The methodology involves full automation of model generation, submission, termination and processing with object-oriented scripting, illustrated using code and pseudocode fragments. (C) 2017 The Authors. Published by Elsevier Ltd.
User or program mobility in distributed computing systems is becoming increasingly significant, since users may sometimes change their working locations. This paper proposes a Logical Machine (LM) system that can effe...
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User or program mobility in distributed computing systems is becoming increasingly significant, since users may sometimes change their working locations. This paper proposes a Logical Machine (LM) system that can effectively support software environment migration and resource mapping. The LM partitions the conventional operating systems into two parts: the Logical Machine Operating System (LMOS) and the Logical Machine Monitor (LMM). They are responsible for user service and system resource management, respectively. The LMM provides a machine independent appearance, called the Logical Machine Interface (LMI), for the upper operating system layers to provide the resources they need. In our experimental system, the LMM contains some disk objects that can be bound dynamically. By varying the binds, the users get different disk characteristics. A mobile disk object with the mechanism of block migration on demand is implemented. It can be incorporated with a logical machine migration facility to achieve job migration, i.e., the user can migrate the operating system and disk blocks to the place he or she desires. The mobile disk also simplifies the mechanism of parallel processing when each server reads and processes its data portion locally. With this approach, the system resources can be mapped more flexibly, while transparency to the operating system is retained. (C) 1997 by John Wiley & Sons, Ltd.
Traditionally, designers obtain the information required for a navigation test by performing classic usability tests, such as watching and listening carefully to, users as they explore the navigation model. However, t...
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Traditionally, designers obtain the information required for a navigation test by performing classic usability tests, such as watching and listening carefully to, users as they explore the navigation model. However, those techniques have crucial drawbacks in terms of the quality and accuracy of the information obtained. In order to avoid these problems, the authors developed ANTS, an Automatic Navigability Testing System based on data-gathering agents.
Software cost estimation is important for budgeting, risk analysis, project planning and software improvement analysis. There are numerous estimation techniques. During the past three decades there had been some signi...
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Software cost estimation is important for budgeting, risk analysis, project planning and software improvement analysis. There are numerous estimation techniques. During the past three decades there had been some significant developments in effort estimation, size of software and cost estimation methodology. Current software cost estimation models have been experiencing increasing difficulties in estimating the costs of software, as new software development methodologies and technologies are emerging very rapidly. Most of the software cost models generally rely on such inputs as estimates of lines of source code, delivered sets of instructions, function points and processing complexity or experience levels to produce cost estimates. These models generally produce inaccurate results when used to estimate the cost of software development in current development environments such as those that use component-based software development environments like visual languages. The authors present in this study a new technique for software cost estimation that can be used for software projects developed using component-based fourth-generation-language environment. The model was calibrated using the empirical data collected from 19 software systems. Efficiency of the model was also compared with an existing model used for such environment. The proposed model achieved better predictive accuracy.
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.
Component-based software development (CBD) is based on building software systems from previously-existing software components. In CBD, reuse of common parts in component form can reduce the development cost of new sys...
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Component-based software development (CBD) is based on building software systems from previously-existing software components. In CBD, reuse of common parts in component form can reduce the development cost of new systems, and reduce the maintenance cost associated with the support of these systems. However, existing programs have usually been built using another paradigm, such as the object-oriented (00) paradigm. 00 programs cannot be reused rapidly or effectively in the CBD paradigm even if they contain reusable functions. In this paper, we propose a technique for extracting components from existing 00 programs by our new refactoring "Extract Component". Our technique of refactoring can identify and extract reusable components composed of classes from 00 programs, and modify the surrounding parts of extracted components in original programs. We have developed a system that performs our refactoring automatically and extracts Java-Beans components from Java programs. As a result of evaluation experiments, it is found that our system is useful for extracting reusable components along with usage examples from Java programs. (c) 2004 Elsevier B.V. All rights reserved.
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
We describe the object-oriented implementation of a higher-order finite-difference density-functional code in Fortran 90. object-oriented models of grid and related objects are constructed and employed for the impleme...
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We describe the object-oriented implementation of a higher-order finite-difference density-functional code in Fortran 90. object-oriented models of grid and related objects are constructed and employed for the implementation of an efficient one-way multigrid method we have recently proposed for the density-functional electronic-structure calculations. Detailed analysis of performance and strategy of the one-way multigrid scheme will be presented. (C) 2000 Elsevier Science B.V. All rights reserved.
Progress in the field of structural optimization naturally leads to an increasing number of structural models and optimization algorithms that need to be considered for design. Software architecture is of central impo...
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Progress in the field of structural optimization naturally leads to an increasing number of structural models and optimization algorithms that need to be considered for design. Software architecture is of central importance in the ability to account for the complex links tying new structural models and optimizers. An object-oriented programming pattern for interfacing simulation and optimization codes is described in this article. The concepts of optimization variable, criteria, optimizers and simulation environment are the building blocks of the pattern. The resulting interface is logical, flexible and extensive. It encompasses constrained single or multiple objective formulations with continuous, discrete or mixed design variables. Applications are given for composite laminate design. (C) 2003 Elsevier Science Ltd. All rights reserved.
An approach to the computer aided analysis of flexible multibody systems using object-oriented programming methods is presented. The aim is to support the rapid generation of specialized programs by providing an open,...
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An approach to the computer aided analysis of flexible multibody systems using object-oriented programming methods is presented. The aim is to support the rapid generation of specialized programs by providing an open, extensible C++ toolkit. This toolkit contains modules (C++ classes) which allow the declaration and manipulation of multibody components such as joints, bodies and actuators in an intuitive manner. New components (e.g., new finite elements) are easily introduced to extend the toolkit. The equations of motion for a multibody system consisting of these components are formulated by direct application of the principle of virtual work using symbolic techniques. It is possible to use absolute as well as relative coordinates in a problem-dependent manner.
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