ACS Applied Computer Science

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vol. 1, no. 1,2005

APPLICATION OF DIFFERENT COMPUTATIONAL ENVIRONMENTS TO OPTIMIZATION OF MAKESPAN IN THE FLOW PRODUCTION LINE

A mathematical model of makespan optimization in the divided flow production line is presented. The methodology of Constraint Programming and Integer Programming to optimization of makespan in the above environment have been considered. Multiple examples illustrate the concept proposed.

CP APPROACH TO DESIGN OF STEADY-STATE FLOW OF REPETITIYE MANUFACTURING PROCESSES IN SME

Concurrent execution of work orders in the smali and medium size enterprises (SME) imposes a necessity to consider many control problems concerning systems of repetitive concurrent manufacturing processes using common resources in mutual exclusion. In many cases a production system with a given structure of the processes resource reąuests can be seen as composed of subsystems with n cyclic processes sharing one resource. For given sets of possible values of the processes operation execution times a problem of finding schedules guaranteeing that no process waits for access to the common resources is considered. In particular for the assigned times of the operations execution a subproblem of finding all possible starting times of work orders execution for which waiting-free schedules exist has been formulated as a constraint programming (CP) problem. The starting times derived can be used as an alternative starting times of work orders execution in case of their possible delays. A State space of the problem ’s solutions has been reduced using constraints based on the necessary and sufficient conditions for existence of a waiting-free n-process steady-state schedule. An illustrative example of Mozart-based software application to the solution of constraint logie programming problem considered has been presented.

TOWARDS CLP-BASED TASK-ORIENTED DSS FOR SME

Decision making supported by task-oriented software tools plays a pivotal role in a modern enterprises. That is because commercially available ERP systems are not able to respond in an interactive on-line/real-time mode. It means a new generation of DSS that enable a fast prototyping of production flows in multiproject environment as well as an integrated approach to a layout planning, production routing, batch-sizing and scheduling problems is needed. In that context, the constraint logie programming techniąues allowing declarative representation of a decision making problem provide a quite attractive alternative. So, some issues regarding modelling of decision making and searching strategies development are discussed in the contribution. The results obtained are implemented in a software package supporting production flow planning in the SMEs. Illustrative example of the ILOG-based software application is provided.

TOWARDS DEDICATED DECISION SUPPORT TOOLS: CLP-BASED APPROACH

Constraint programming (CP) is an emergent software technology for declarative description and effective solving of large combinatorial problems especially in areas of integrated production planning. In that context, the CP can be considered as a well-suited framework for development of decision making software supporting smali and medium size enterprises in the course of Production Process Planning (PPP). The problem considered regards of finding of computationally effective approach aimed at scheduling of a new project subject to constraints imposed by a multi-project environment. In other words, we are looking for an answer whether a given production order specified by its cost and completion time can be accepted in a given manufacturing system specified by available production capability, i.e., the time-constrained resources availability. The problem belongs to a class of multi-mode case project scheduling problems, where the problem of finding a feasible solution is NP-complete. The aim of the paper is to present the CP modeling framework as well as to illustrate its application to decision making in the case of a new production order evaluation. So, the contribution emphasizes benefits derived from CP-based DSS and focuses on constraint satisfaction driven decision-making rather than on an optimal solution searching.

AN APPROACH TO TIME PROJECT ORIENTED MANAGEMENT

The objective presented below is to answer the ąuestion: How to exploit resources to complete all projects in expected time in a multi-project ernironment? A solution to maximise the number of projects, which the company is able to implement concurrently is proposed by combining the Theory of Constraints and conditions guaranteeingproject due dates with constraint-based scheduling.

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