Browsing by Subject "Genetic Algorithms"

Now showing 1 - 5 of 5

Open Access
Assembly line balancing using genetic algorithms
(1997) Tanyer, Muzaffer
For the last few decades, the genetic algorithms (GAs) have been used as a kind of heuristic in many areas of manufacturing. Facility layout, scheduling, process planning, and assembly line balancing are some of the areas where GAs are already popular. GAs are more efficient than traditional heuristics and also more flexible as they allow substantial changes in the problem’s constraints and in the solution approach with small changes in the program. For this reason, GAs attract the attention of both the researchers and practitioners. Chromosome structure is one of the key components of a GA. Therefore, in this thesis, we focus on the special structure of the assembly line balancing px'oblem and design a chromosome structure that operates dynamically. We propose a new mechanism to work in parallel with GAs, namely dynamic partitioning. Different from many other GA researchers, we particularly compare different population re\asion mechanisms and the effect of elitism on these mechanisms. Elitism is revised by the simulated annealing idea and various levels of elitism are created and their effects are observed. The proposed GA is £ilso compared with the traditional heuristics.
Open Access
An evolutionary basic design tool
(2010) Akbulut, Dilek
As a creative act, design aims at achieving innovative solutions to fulfill the requirements provided in the problem definition. In recent years, computational methods began to be used not only in design presentation but also in solution generation. The study proposes a design methodology for a particular basic design problem on the concept of emphasis. The developed methodology generates solution alternatives by carrying out genetic operations used in evolutionary design. The generated alternatives are evaluated by an objective function comprising an artificial neural network. The creative potential of the methodology is appraised by comparing the outputs of test runs with the student works for the same design task. In doing so, three different groups of students with diverse backgrounds are used.
Open Access
A genetic algorithm-based search for parametric reform alternatives for the Turkish pension system : 2005-2060
(2005) Alparslan, Mustafa Artun
In this thesis, we search for parametric reform alternatives so as to achieve a balance in the long term accumulated difference between pension expenditures and revenues of the SSI, the largest pension fund in Turkey, from 2005 to 2060. The projected worker-retiree composition of the pension system is allowed to change along with proposed policy changes in contribution and replacement rates. These changes in population structure are modeled by estimated work and pension income elasticities of labor supply values so that the resulting changes in the incomes of the worker could now affect the retirement decision. Possible policy alternatives are then found by a genetic algorithm developed for this purpose. Finally, the results obtained from the program are compared with previous and current reform proposals.
Open Access
Multicriteria inventory classification using a genetic algorithm
(Elsevier, 1998) Guvenir, H. A.; Erel, E.
One of the application areas of genetic algorithms is parameter optimization. This paper addresses the problem of optimizing a set of parameters that represent the weights of criteria, where the sum of all weights is 1. A chromosome represents the values of the weights, possibly along with some cut-off points. A new crossover operation, called continuous uniform crossover, is proposed, such that it produces valid chromosomes given that the parent chromosomes are valid. The new crossover technique is applied to the problem of multicriteria inventory classification. The results are compared with the classical inventory classification technique using the Analytical Hierarchy Process. © 1998 Elsevier Science B.V.
Open Access
Two novel multiway circuit partitioning algorithms using relaxed locking
(IEEE, 1997) Dasdan, A.; Aykanat, Cevdet
All the previous Kernighan-Lin-based (KL-based) circuit partitioning algorithms employ the locking mechanism, which enforces each cell to move exactly once per pass. In this paper, we propose two novel approaches for multiway circuit partitioning to overcome this limitation. Our approaches allow each cell to move more than once. Our first approach still uses the locking mechanism but in a relaxed way. It introduces the phase concept such that each pass can include more than one phase, and a phase can include at most one move of each cell. Our second approach does not use the locking mechanism at all. It introduces the mobility concept such that each cell can move as freely as allowed by its mobility. Each approach leads to KL-based generic algorithms whose parameters can be set to obtain algorithms with different performance characteristics. We generated three versions of each generic algorithm and evaluated them on a subset of common benchmark circuits in comparison with Sanchis' algorithm (FMS) and the simulated annealing algorithm (SA). Experimental results show that our algorithms are efficient, they outperform FMS significantly, and they perform comparably to SA. Our algorithms perform relatively better as the number of parts in the partition increases as well as the density of the circuit decreases. This paper also provides guidelines for good parameter settings for the generic algorithms. © 1997 IEEE.