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 discrete artificial bee colony algorithm for the permutation flowshop scheduling problem with sequence-dependent setup times

Abstract: A discrete artificial bee colony (DABC) algorithm for the permutation flowshop scheduling problem with sequence-dependent setup times (PFSP-SDST) is presented in this paper. PFSP-SDST is an important problem that has practical applications in production facilities. The proposed DABC algorithm uses destruction and construction procedure to generate neighboring food sources. In addition, a local search algorithm with insert and swap neighborhoods is used to enhance the solution quality. The main contribution of this work is providing a speedup algorithm for the swap neighborhood. Computational experiments are carried out to test the performance of the algorithm on a benchmark problem set from the literature. Experimental results show that the proposed DABC algorithm utilizing swap neighborhood is very competitive to the best performing algorithms from the literature.

Hospital layout design renovation as a Quadratic Assignment Problem with geodesic distances

Abstract: Hospital facilities are known as functionally complex buildings. There are usually configurational problems that lead to inefficient transportation processes for patients, medical staff, and/or logistics of materials. The Quadratic Assignment Problem (QAP) is a well-known problem in the field of Operations Research from the category of the facility's location/allocation problems. However, it has rarely been utilized in architectural design practice. This paper presents a formulation of such logistics issues as a QAP for space planning processes aimed at renovation of existing hospitals, a heuristic QAP solver developed in a CAD environment, and its implementation as a computational design tool designed to be used by architects. The tool is implemented in C# for Grasshopper (GH), a plugin of Rhinoceros CAD software. This tool minimizes the internal transportation processes between interrelated facilities where each facility is assigned to a location in an existing building. In our model, the problem of assignment is relaxed in that a single facility may be allowed to be allocated within multiple voxel locations, thus alleviating the complexity of the unequal area assignment problem. The QAP formulation takes into account both the flows between facilities and distances between locations. The distance matrix is obtained from the spatial network of the building by using graph traversal techniques. The developed tool also calculates spatial geodesic distances (walkable, easiest, and/or shortest paths for pedestrians) inside the building. The QAP is solved by a heuristic optimization algorithm, called Iterated Local Search. Using one exemplary real test case, we demonstrate the potential of this method in the context of hospital layout design/re-design tasks in 3D. Finally, we discuss the results and possible further developments concerning a generic computational space planning framework.

Return range and the cross-section of expected index returns in international stock markets

Abstract: This study examines the cross-sectional relation between return range and future returns for the first time in literature. We show that the return range can serve as a very practical measure of total volatility instead of standard deviation due to the range's high correlation with standard deviation and strong predictive ability. Range, standard deviation, and idiosyncratic volatility are cross-sectionally linked to future returns on indexes of small size, while earnings-to-price ratio and net share issuance predict returns of mid-cap and large-cap indexes, respectively. Maximum and minimum return effects along with the momentum effect are prevalent in returns of indexes of any size but stronger for small-cap indexes.