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Conference Object Citation - WoS: 1Optimal Energy Efficient Routing in Wireless Sensor Networks With Link Asymmetry(Ieee, 2012) Ozyer, Sibel T.; Tavli, Bulent; Koyuncu, MuratIn Wireless Sensor Networks (WSNs), link unidirectionality is an unavoidable phenomenon. The existence of unidirectional links can be attributed to several physical factors induced by the transceiver characteristics as well as other environmental phenomena. Transmission power heterogeneity is the dominant paradigm that leads to unidirectionality. In this study, we investigate the effects of transmission power heterogeneity on the lifetime of WSNs through a novel Linear Programming (LP) framework both for networks that utilize only bidirectional links and for those that can use unidirectional links in addition to bidirectional links. Our results show that transmission power heterogeneity can lead to more than 25 % decrease in network lifetime for protocols that can operate only on bidirectional links when compared to a network without any heterogeneity. However, if the use of unidirectional links is also enabled then, the decrease in network lifetime is at most 12 %.Conference Object Citation - Scopus: 1Optimal energy efficient routing in wireless sensor networks with link asymmetry(2012) Ozyer,S.T.; Tavli,B.; Koyuncu,M.In Wireless Sensor Networks (WSNs), link unidirectionality is an unavoidable phenomenon. The existence of unidirectional links can be attributed to several physical factors induced by the transceiver characteristics as well as other environmental phenomena. Transmission power heterogeneity is the dominant paradigm that leads to unidirectionality. In this study, we investigate the effects of transmission power heterogeneity on the lifetime of WSNs through a novel Linear Programming (LP) framework both for networks that utilize only bidirectional links and for those that can use unidirectional links in addition to bidirectional links. Our results show that transmission power heterogeneity can lead to more than 25 % decrease in network lifetime for protocols that can operate only on bidirectional links when compared to a network without any heterogeneity. However, if the use of unidirectional links is also enabled then, the decrease in network lifetime is at most 12 %. © 2012 IEEE.Article Citation - WoS: 2A Model To Evaluate Supply Chain Performance and Flexibility(Academic Journals, 2011) Bac, Ugur; Erkan, Turan ErmanIn present day's global competitive environment, enterprises have to focus on their supply chain performance to have a competitive advantage. Improving the effectiveness of the system is the only way to do so and, for this purpose, ongoing supply chain activities have to be inspected in pursuant of some performance measurements and metrics to cover the concept. There is a lack of effective mathematical models in the literature which enclose flexibility and its parameters in order to measure the performance of a supply chain by considering all of its vital elements. In this paper, a mathematical model is proposed to evaluate supply chain performance using some key performance indicators. This model can be used to evaluate the flexibility characteristics of logistic, market, supplier, machine, labor, information system, and routing of the supply chain.
