Yaşar University

About: Yaşar University is a education organization based out in Izmir, Turkey. It is known for research contribution in the topics: Exergy & Job shop scheduling. The organization has 760 authors who have published 1436 publications receiving 20813 citations. The organization is also known as: Yaşar Üniversitesi.

A differential evolution algorithm for the median cycle problem

Abstract: This paper extends the applications of differential evolution algorithms to the Median Cycle Problem. The median cycle problem is concerned with constructing a simple cycle composed of a subset of vertices of a mixed graph. The objective is to minimize the cost of the cycle and the cost of assigning vertices not on the cycle to the nearest vertex on the cycle. A unique solution representation is presented for the differential evolution algorithm in order to solve the median cycle problem. To the best of our knowledge, this is the first reported application of differential evolution algorithms to the median cycle problem in the literature. No local search is employed in order to see the performance of the pure differential evolution algorithm. The differential evolution algorithm is tested on a set of benchmark instances from the literature. For comparisons, a continuous genetic algorithm is also developed. The computational results show that the differential evolution algorithm was superior to the genetic algorithm. In addition, the computational results also show that the differential evolution algorithm is very promising in solving the median cycle problem when compared to the best performing algorithms from the literature. Ultimately, given the fact that no local search is employed, the DE algorithm was able to further improve the 5 out of 20 instances.

Geçmişten Günümüze Keçe: Ayfer Güleç İş Modeli Üzerine Bir Analiz

Abstract: Bir toplumun uretim ve tuketim bicimi, o toplumun geleneksel sanat ve zanaatlarini, kulturel mirasini olusturmaktadir. Endustrilesme ve kuresellesmeyle birlikte, buyuk olcekli uretim-tuketim bicimi, kulturleri olumsuz etkilemis, toplumlarin geleneksel, yerel sanat ve zanaatlarinin kaybolusuna sebep olmustur. Bir toplumun yerelliginin ve kulturel mirasinin yok olusu, o kulturun kendine hasligini kaybetmesine, kuresellesmenin etkisiyle diger kulturlerle aynilasmasinda onemli bir rol oynamaktadir. Kececilik, modernlesme surecinde Turkiye’de yok olan geleneksel bir zanaattir. Gunumuzde, tasarimci ve sanatcilar, kecenin ekolojik bir malzeme olmasina duyduklari ilgiyle keceden urunler tasarlamaya ve eserler yaratmaya baslamislardir. Boylece kece ve kece yapimi yeniden guncellesmekte, kece nesneler ve giysiler, gundelik hayatta yerini almaktadir. Bu calismada, bu geleneksel yapim ve yaratim bilgisinin, sanat, tasarim bilgisi ve eylemleri araciligiyla nasil surduruldugu ve guncellendigi arastirilmistir. Oncelikle, kececiligin tarihi ve yok olus nedenlerine deginilmis; Turkiye’de keceyle calismalar yapan sanatci, tasarimci ve ustalarin calismalari incelenip, kececilik ve tasarim konusunda bir girisimci olan Ayfer Gulec’in is modeli ornek bir vaka olarak analiz edilmistir. Sonuc degerlendirmesinde, Gulec’in tasarim merkezli is modeli, Turkiye’de yok olan diger somut olmayan kulturel mirasin geri kazanimi konusunda ornek bir is modeli olarak onerilmektedir. Anahtar Sozcukler: Geleneksel Kececilik, Somut Olmayan Kulturel Miras, Zanaat, Kece Tasarimi, Tekstil Tasarimi, Nesne Tasarimi, Tasarima-Dayali Is Modeli.

Teaching object oriented programming at the introductory level

Abstract: Teaching object oriented programming has become a rapidly expanding preference at various educational environments. However, teachers usually experience problems when introducing object oriented concepts and programming to beginners. How to teach the fundamentals of object oriented programming at an introductory level course is still a common subject for debate. In this paper, an evaluation of these problems is presented and some possible approaches for improving the quality and success of such courses are discussed.

Determining reliability by failure rate estimation via a new parameter

Abstract: There are many methods and standards to predict reliability. Stress based standards are widely used. Also, most of the companies perform accelerated life tests and analyze their test data with statistical distributions. However, every standard and statistical distribution gives different reliability predictions and these predictions differ from the field values. The reason for this is that, stress based standards and accelerated life tests may not consider every type of stress factors and failure mechanisms seen in the field. The main stress factors mentioned in stress based standards are tem perature, voltage and power dissipation. In addition, the main stress factors used in accelerated life tests are temperature, relative humidity, voltage and vibration. However, those stress factors are not the only failure reasons of the products in the field. For example, ESD, Inrush Current, Voltage Dips-Interruptions-Variations, Lightning, Loose Plugs etc. can cause failures in the field. Therefore, there should be a parameter which can express these failure mechanisms and this new parameter should be combined with traditional prediction methods to predict the failure rate and reliability of the product more accurately. In this paper, determining reliability by failure rate estimation with a new parameter in R&D phase is introduced. This new parameter is obtained by applying a set of electrical, environmental and mechanical tests in R&D phase, before mass production. This set of tests is created as it should be able to simulate different stress factors and failure mechanisms faced in the field. These tests can also be approval and validation tests at both board and product level. A scoring point is given to every test according to the severity of the test. The severity of the test can be decided by analyzing similar projects' field returns. A test which gives more information about failures will have higher scoring points. At the end, the total point of the tests is obtained. On the other hand, a losing point is given to every failure which is found during testing according to its severity. The severity of the failure can also be decided by analyzing similar projects' field returns. After all tests are performed, total losing points will be calculated. The new parameter mentioned above is de fined as the ratio of losing points to total test points. Finally, a new parameter which can express different stress factors and failure mechanisms faced in the field is obtained. This new parameter is combined with failure rate calculations from traditional methods. Therefore, failure rate and return rate predictions are modified. In addition, in this paper two mathematical models of combination of this new parameter with stress based failure rate prediction and failure rate calculated by applying accelerated life tests are given with a real life case study. The results of these two methods and the comparison of the results with the real data are also given.