Optimization of Block Erection Using a Genetic Algorithm

2002 ◽  
Vol 18 (02) ◽  
pp. 116-119
Author(s):  
Yasuhisa Okumoto
Keyword(s):  
Genetic Algorithm ◽  
Computer Simulation ◽  
Simulation Method ◽  
Measurement Technology ◽  
Skilled Workers ◽  
Productivity Improvement ◽  
Optimum Position ◽  
Efficient Measurement ◽  
Dimensional Errors ◽  
Positional Control

Block erection is a very important and demanding skill in shipbuilding quality control as well as in productivity improvement. Though this work at the present time depends on skilled workers in the yards, these workers eventually become old and retire, and then the training of their successors, or other countermeasures, will be required. Recently, CAD and CIM systems have been applied widely, and also efficient measurement technology has been developed in the shipyard; thus it has become possible to apply positional control at the erection stage by computer simulation. This paper presents a computer simulation method to place a block, which has dimensional errors, in a suitable position as designed using a genetic algorithm (GA). A pilot program using a personal computer has been developed and applied to a typical hexahedron block. The simulation results showed good agreement in achieving the optimum position.

scholarly journals Using Computer Simulation Method to Improve Throughput of Production Systems by Buffers and Workers Allocation

2015 ◽  
Vol 6 (4) ◽  
pp. 60-69 ◽  
Author(s):  
Sławomir Kłos ◽  
Peter Trebuna
Keyword(s):  
Computer Simulation ◽  
Production System ◽  
Production Systems ◽  
Simulation Method ◽  
System Throughput ◽  
Buffer Allocation ◽  
Simulation Experiments ◽  
Buffer Capacities ◽  
The Relationship ◽  
Support Decision Making

Abstract This paper proposes the application of computer simulation methods to support decision making regarding intermediate buffer allocations in a series-parallel production line. The simulation model of the production system is based on a real example of a manufacturing company working in the automotive industry. Simulation experiments were conducted for different allocations of buffer capacities and different numbers of employees. The production system consists of three technological operations with intermediate buffers between each operation. The technological operations are carried out using machines and every machine can be operated by one worker. Multi-work in the production system is available (one operator operates several machines). On the basis of the simulation experiments, the relationship between system throughput, buffer allocation and the number of employees is analyzed. Increasing the buffer capacity results in an increase in the average product lifespan. Therefore, in the article a new index is proposed that includes the throughput of the manufacturing system and product life span. Simulation experiments were performed for different configurations of technological operations.

Basic Studies for the Automatic Fabrication of Welded Built-up Beams

1995 ◽  
Vol 11 (02) ◽  
pp. 111-116 ◽  
Author(s):  
Chang Doo Jang ◽  
Seung II Seo
Keyword(s):  
Welding Current ◽  
Simulation Method ◽  
Welding Deformation ◽  
Skilled Workers ◽  
Fabrication Cost ◽  
Current Voltage ◽  
Fabrication Procedure ◽  
Increase In Productivity ◽  
Study Techniques ◽  
Basic Studies

In the fabrication of welded built-up beams, longitudinal deformation occurs due to welding. As it prevents improvement of productivity and quality, heating for straightening the welding deformation is necessary. Therefore, control of the deformation due to welding and heating is the base for the automatic fabrication of built-up beams. In this study, techniques to control the deformation are developed. Based on the simple formulas for estimation of the deformation proposed in the previous study, a procedure to calculate the required reverse curvatures to straighten the welding deformation is presented and a method to simulate the fabrication procedure is developed. From the simulation of the fabrication procedure it is concluded that, in heating for straightening, deep-heated depth is more economical than wide-heated breadth in yielding the same curvature. To apply the results obtained to automatic fabrication, welding and heating parameters such as welding current, voltage and speed, and heated depth and breadth are selected and fabrication cost is expressed by the parameters, which are optimized under the constraints. According to the optimized results, the higher welding current reduces the fabrication cost. Results obtained through executing the simulation method described herein can be used in the guidance of welding and heating procedures instead of depending on the experience of skilled workers--and this can contribute to an increase in productivity and quality.

Breast Cancer: Computer Simulation Method for Estimating Optimal Intervals for Screening

Radiology ◽  
1999 ◽  
Vol 212 (2) ◽  
pp. 551-560 ◽  
Author(s):  
James S. Michaelson ◽  
Elkan Halpern ◽  
Daniel B. Kopans
Keyword(s):  
Breast Cancer ◽  
Computer Simulation ◽  
Simulation Method ◽  
Computer Simulation Method

The Use of Computer Simulation of Merged Variation to Predict Rework Levels on Ship's Hull Blocks

1988 ◽  
Vol 4 (03) ◽  
pp. 155-168
Author(s):  
R.L. Storch ◽  
P.J. Giesy
Keyword(s):  
Computer Simulation ◽  
Probability Distribution ◽  
Subsequent Development ◽  
Simulation Method ◽  
Simulation Program ◽  
Modular Construction ◽  
Accuracy Control ◽  
Probability Curve ◽  
Productivity Losses ◽  
Computer Simulation Program

In the modular construction of ships, significant productivity losses can occur during the erection stage, when the modules, or hull blocks, are joined together. Frequently, adjacent blocks do not fit together properly, and rework of one or both of the mating block interfaces is necessary to correct the problem. The specific cause of rework is the variation of plate edges at the block interface, which is itself a cumulative product of numerous manufacturing variations inherent in hull block construction. Variation in manufacturing is unavoidable, but not uncontrollable. The application of accuracy control techniques in shipbuilding has proven that a statistical analysis of variation makes possible an accurate prediction of its effects. This paper presents an examination of block interface variation, and the subsequent development of a computer simulation method of predicting rework levels on those blocks. The complex interaction of all the edges' random variations at the block interface gives rise to a unique rework probability distribution. This probability distribution is evaluated by means of the computer simulation program, which provides estimates of the average rework anticipated, the shape of the probability curve, and other parameters. Similar predictions are also available for cost and labor of required rework. In addition to predicting rework levels, the simulation program can be a useful tool for reducing those levels.

Highly Efficient Measurement Technology Based on Hyper-Spectropolarimetric Imaging

2016 ◽  
Vol 43 (8) ◽  
pp. 0811001
Author(s):  
薛鹏 Xue Peng ◽  
王志斌 Wang Zhibin ◽  
张瑞 Zhang Rui ◽  
王耀利 Wang Yaoli ◽  
刘顺 Liu Shun
Keyword(s):  
Measurement Technology ◽  
Highly Efficient ◽  
Efficient Measurement
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