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 Variable Block Insertion Heuristic for the Blocking Flowshop Scheduling Problem with Total Flowtime Criterion

Abstract: In this paper, we present a variable block insertion heuristic (VBIH) algorithm to solve the blocking flowshop scheduling problem with the total flowtime criterion. In the VBIH algorithm, we define a minimum and a maximum block size. After constructing the initial sequence, the VBIH algorithm starts with a minimum block size being equal to one. It removes the block from the current sequence and inserts it into the partial sequence sequentially with a predetermined move size. The sequence, which is obtained after several block moves, goes under a variable local search (VLS), which is based on traditional insertion and swap neighborhood structures. If the new sequence obtained after the VLS local search is better than the current sequence, it replaces the current sequence. As long as it improves, it keeps the same block size. However, if it does not improve, the block size is incremented by one and a simulated annealing-type of acceptance criterion is used to accept the current sequence. This process is repeated until the block size reaches at the maximum block size. Furthermore, we present a novel constructive heuristic, which is based on the profile fitting heuristic from the literature. The proposed constructive heuristic is able to further improve the best known solutions for some larger instances in a few seconds. Parameters of the constructive heuristic and the VBIH algorithm are determined through a design of experiment approach. Extensive computational results on the Taillard’s well-known benchmark suite show that the proposed VBIH algorithm outperforms the discrete artificial bee colony algorithm, which is one of the most efficient algorithms recently in the literature. Ultimately, 52 out of the 150 best known solutions are further improved with substantial margins.

Long-term post-fire dynamics of co-occurring woody species in Pinus brutia forests: the role of regeneration mode

Abstract: Regeneration mode is one of the key attributes determining population structure and dynamics of plant species. We investigated long-term patterns after fire in the cover of plant species in a 100-year chronosequence of burned Pinus brutia forests in a humid Mediterranean climate region in Turkey. Significant trends were present in the change of cover in major species through post-fire chronosequence, and species with similar trends were clustered in relation to their regeneration modes. Obligate resprouters increased their cover from the early post-fire years to the later stages, while cover of obligate seeders with a soil seed bank increased in the early years, but then decreased through time. Facultative resprouters were at an intermediate position, with an increase in cover until mid-successional stages and then a decrease through time. The cover of the only obligate seeder with a canopy seed bank (P. brutia) followed a linear increasing trend during the succession. When species with the same regeneration mode were grouped, the same trends were observed with more explained variances. A few life-history traits were enough to explain the observed trends. Our study shows that regeneration mode is an explanatory functional grouping system for describing long-term post-fire dynamics of Mediterranean Basin woody species. We suggest that regeneration mode must be a major component of any vegetation or forest stand dynamics model in the Mediterranean Basin. This result has important implications for the management of Mediterranean Basin ecosystems, and can potentially be extrapolated to other Mediterranean-type fire-prone ecosystems.