An object-oriented scheduling system for a job-shop manufacturing cell has been developed and tested. A powerful optimization technique based on genetic algorithms was used to improve the routing of subassembly parts ...
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An object-oriented scheduling system for a job-shop manufacturing cell has been developed and tested. A powerful optimization technique based on genetic algorithms was used to improve the routing of subassembly parts in the manufacturing cell. The scheduling system is composed of three interactive modules: the due date algorithms, the genetic algorithms, and the manufacturing cell simulator. These modules exchange information to accomplish 'genetic optimization' and to fulfill time-dependent and technological constraints simultaneously, using a composite objective function. The due date algorithms use the production sequences and processing times of individual parts of a single product to generate production priorities. The genetic algorithms module creates a population of feasible machine routings and schedules, and passes it on to the manufacturing cell simulator. The manufacturing cell simulator performs the production plans under different scheduling configurations. The genetic algorithms module uses the fitness value of each scheduling alternative progressively to improve the production schedule until a convergence criterion is satisfied. (C) 1997 Elsevier Science B.V.
Program slicing is a decomposition technique that deals with extracting those statements relevant to a particular computation. The authors propose a novel algorithm for computing dynamic slice of distributed object-or...
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Program slicing is a decomposition technique that deals with extracting those statements relevant to a particular computation. The authors propose a novel algorithm for computing dynamic slice of distributed object-oriented programs. The proposed algorithm incorporates graph colouring strategy to compute slice. But to achieve the goal efficiently, the authors have contradicted some key constraints of the traditional graph colouring technique. The state restriction of the slicing criterion is also considered along with dependence analysis while computing slice. The advantage of the proposed algorithm is that it is efficient and faster than the existing algorithms.
Traditional scheduling tools for continuous process industries have not been developed with batch processing in mind. Efficient batch processing requires intelligent scheduling tools. The principal contribution of thi...
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Traditional scheduling tools for continuous process industries have not been developed with batch processing in mind. Efficient batch processing requires intelligent scheduling tools. The principal contribution of this research is the development of an architecture which combines intelligent tools with a virtual plant for performing management tasks. One of the intelligent tools, a flexible scheduling algorithm based on object-oriented constructs to schedule batch processes, is presented. A virtual plant is used to map chemical processes with equipment in the plant. The scheduling algorithm then uses a database of current customer orders and a knowledge base that contains rules about customer priority, equipment cleaning, process preference, equipment history, batch sequencing rules, cost history, cost estimates, and other knowledge to aid the user in the selection of the appropriate schedule. The uniqueness of this approach is the integration of a virtual plant, which can be viewed as a static plant simulation model, with a rule-based scheduling approach.
An explanation is given of showing a computer what to do by directly manipulating objects, as opposed to giving it instructions using a programming language. The authors demonstrate how showing can take advantage of a...
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An explanation is given of showing a computer what to do by directly manipulating objects, as opposed to giving it instructions using a programming language. The authors demonstrate how showing can take advantage of a standard user interface and the consistency of a user interface paradigm. They discuss prototyping in the Oregon Speedcode Universe, a programming system for writing programs without programming languages
Legacy systems often contain several crosscutting concerns that could potentially benefit from an aspect-orientedprogramming implementation. In this paper, we focus on the problem of aspect identification in existing...
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Legacy systems often contain several crosscutting concerns that could potentially benefit from an aspect-orientedprogramming implementation. In this paper, we focus on the problem of aspect identification in existing code. The main idea is that use-cases can be defined in order to separate the base logics from the crosscutting concerns to be aspectised. The relationship between the execution traces associated with the use-cases and the executed computational units (class methods) is analysed through concept analysis. The results obtained on some case studies are discussed in the paper.
Minimum cost wavelength-path routing and wavelength allocation of multiwavelength alloptical transport networks using a genetic-algorithm (GA)/heuristic hybrid approach is described. A cost model is adopted which inco...
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Minimum cost wavelength-path routing and wavelength allocation of multiwavelength alloptical transport networks using a genetic-algorithm (GA)/heuristic hybrid approach is described. A cost model is adopted which incorporates a dependency on link wavelength requirements. The hybrid algorithm developed uses an object-oriented representation of networks, and incorporates four operators: path mutation, single-point crossover, reroute and shift-out. In addition, an operator-probability adaptation mechanism is employed to improve operator productivity. Experimental results from seven fifteen-node test networks, obtained using a tool for optical network optimisation, modelling and design (NOMaD), suggest the GA/heuristic hybrid approach provides superior results compared to three recent wavelength-allocation heuristics, except when the network cost depends most heavily on wavelength requirement.
This paper presents a computer-aided planning system that is capable of generating assembly sequences for aircraft frame assemblies. The representation scheme for aircraft frame assemblies is first described. Algorith...
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This paper presents a computer-aided planning system that is capable of generating assembly sequences for aircraft frame assemblies. The representation scheme for aircraft frame assemblies is first described. Algorithms for the automated generation of assembly sequences are then discussed. The planning system takes assembly drawing and bill of material as inputs. In consideration of both the geometric and technical constraints in the planning stage, the system generates an assembly sequence as output. The system has been implemented using an object-oriented approach (C++) and a graphical user interface under MS-Windows. A spar subassembly is used to demonstrate the working of the methodology as well as the implemented system.
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.
This paper is organized as follows. Part A presents the context of reconfiguring transitic systems and the main idea in implementing the decision step. It comprises sections 1 to 3. Section 3 presents an example that ...
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This paper is organized as follows. Part A presents the context of reconfiguring transitic systems and the main idea in implementing the decision step. It comprises sections 1 to 3. Section 3 presents an example that illustrates the concepts presented in the next sections. Parts B and C express the models and principles used to simulate transitic systems, the result of which will be helpful for choosing the new configuration. Part B focuses mainly on models. It comprises sections 4 to 6. Part C focuses mainly on simulation principles. It comprises sections 7 to 10.
This research examines the structural complexity of software and, specifically, the potential interaction of the two dominant dimensions of structural complexity, coupling and cohesion. Analysis based on an informatio...
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This research examines the structural complexity of software and, specifically, the potential interaction of the two dominant dimensions of structural complexity, coupling and cohesion. Analysis based on an information processing view of developer cognition results in a theoretically driven model with cohesion as a moderator for a main effect of coupling on effort. An empirical test of the model was devised in a software maintenance context utilizing both procedural and object-oriented tasks, with professional software engineers as participants. The results support the model in that there was a significant interaction effect between coupling and cohesion on effort, even though there was no main effect for either coupling or cohesion. The implication of this result is that, when designing, implementing, and maintaining software to control complexity, both coupling and cohesion should be considered jointly, instead of independently. By providing guidance on structuring software for software professionals and researchers, these results enable software to continue as the solution of choice for a wider range of richer, more complex problems.
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