Mekatronik Mühendisliği Bölümü

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Citation - WoS: 3
Citation - Scopus: 8
An Electromagnetic Micro-Power Generator for Low Frequency Vibrations With Tunable Resonance
(Elsevier Science Bv, 2011) Turkyilmaz, S.; Zorlu, O.; Muhtaroglu, A.; Kulah, H.
This paper presents an electromagnetic (EM) micro-power generator with tunable resonance frequency which can harvest energy from low frequency environmental vibrations. The reported power generator up-converts low frequency environmental vibrations before mechanical-to-electrical energy conversion by utilizing two diaphragms with different resonance frequencies. Power is generated through electromagnetic induction by a magnet attached to the low frequency diaphragm, and a 50 turn, 2.1 Omega coil, and a magnetic piece on the high frequency diaphragm. Both of the diaphragms are fixed to a common frame via rubber springs, which makes the resonance frequency of each diaphragm tunable. The fabricated prototype generates 5.2 mV and 3.21 mu W RMS power by up-converting 13 Hz, 7.5 mm peak-to-peak vibrations to 200 Hz. Tunability of the resonance frequency is experimentally verified by operating the same device at 2-30 Hz external vibrations. (C) 2011 Published by Elsevier Ltd.
Citation - WoS: 64
Citation - Scopus: 67
Robust Optimization Models for the Discrete Time/Cost Trade-Off Problem
(Elsevier Science Bv, 2011) Hazir, Oncu; Erel, Erdal; Gunalay, Yavuz
Developing models and algorithms to generate robust project schedules that are less sensitive to disturbances are essential in today's highly competitive uncertain project environments. This paper addresses robust scheduling in project environments; specifically, we address the discrete time/cost trade-off problem (DTCTP). We formulate the robust DTCTP with three alternative optimization models in which interval uncertainty is assumed for the unknown cost parameters. We develop exact and heuristic algorithms to solve these robust optimization models. Furthermore, we compare the schedules that have been generated with these models on the basis of schedule robustness. (C) 2010 Elsevier B.V. All rights reserved.
Citation - WoS: 101
Robust Scheduling and Robustness Measures for the Discrete Time/Cost Trade-Off Problem
(Elsevier Science Bv, 2010) Hazir, Oencue; Haouari, Mohamed; Erel, Erdal
Projects are often subject to various sources of uncertainties that have a negative impact on activity durations and costs. Therefore, it is crucial to develop effective approaches to generate robust project schedules that are less vulnerable to disruptions caused by uncontrollable factors. In this paper, we investigate the robust discrete time/cost trade-off problem, which is a multi-mode project scheduling problem with important practical relevance. We introduce surrogate measures that aim at providing an accurate estimate of the schedule robustness. The pertinence of each proposed measure is assessed through computational experiments. Using the insights revealed by the computational study, we propose a two-stage robust scheduling algorithm. Finally, we provide evidence that the proposed approach can be extended to solve a complex robust problem with tardiness penalties and earliness revenues. (C) 2010 Elsevier B.V. All rights reserved.

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