Mekatronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/255
Browse
19 results
Search Results
Article Citation - WoS: 4Citation - Scopus: 4String Stability Under Actuator Saturation on Straight Level Roads: Sufficient Conditions and Optimal Trajectory Generation(Ieee-inst Electrical Electronics Engineers inc, 2022) Bingol, Hilal; Schmidt, Klaus WernerThe heterogeneity of vehicles is an important factor when realizing cooperative adaptive cruise control (CACC) in practice. Specifically, it has to be considered that platoons generally consist of vehicles with both different dynamic properties and actuator limits on the engine and braking force, which is expected to have a negative impact on important properties such as string stability. Accordingly, the subject of this paper is the preservation of string stability for CACC in heterogeneous vehicle strings with potential actuator saturation. To this end, the paper formulates a velocity-dependent force bound that enables the derivation of sufficient conditions for preserving string stability during velocity changes of heterogeneous platoons. These conditions are then used for the analytical computation of trajectories for time-optimal velocity changes. The formal results of the paper are supported by an illustrative simulation study.Article Citation - WoS: 51Citation - Scopus: 54Functionally Graded Hollow Cylinder Under Pressure and Thermal Loading: Effect of Material Parameters on Stress and Temperature Distributions(Pergamon-elsevier Science Ltd, 2018) Gulgec, Mufit; Evci, CelalThis study presents an analytical solution of stresses and displacements in a long functionally graded (FGM) hollow cylinder subjected to uniform heat generation and internal pressure. Thermo-elastic material properties of FGM cylinder continuously vary in radial direction along the thickness with a power function. The temperature distribution is assumed to vary as a function of the radial coordinate and in steady state. Stress formulation approach is employed using the Airy stress function to derive the analytical solution. In the failure analysis of FGM cylinder, Coulomb-Mohr theory is applied for the ceramic phase whereas Tresca yield criterion is used for the metal phase. The stress analysis reveals that stresses in FGM cylinder decrease considerably, compared to the homogenous one, for a particular interval of material parameters. Radial displacement analysis in FGM cylinder supports the results obtained from stress analysis. (C) 2017 Elsevier Ltd. All rights reserved.Article Citation - WoS: 102Robust Scheduling and Robustness Measures for the Discrete Time/Cost Trade-Off Problem(Elsevier Science Bv, 2010) Hazir, Oencue; Haouari, Mohamed; Erel, ErdalProjects 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.Article Citation - WoS: 65Citation - Scopus: 67Robust Optimization Models for the Discrete Time/Cost Trade-Off Problem(Elsevier Science Bv, 2011) Hazir, Oncu; Erel, Erdal; Gunalay, YavuzDeveloping 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.Article Citation - WoS: 32Citation - Scopus: 36Sers-Based Ultrafast and Sensitive Detection of Luteinizing Hormone in Human Serum Using a Passive Microchip(Elsevier Science Sa, 2018) Yildirim, Ender; Eryilmaz, Merve; Selbes, Yesim; Saglam, Necdet; Tamer, Ugur; Gjergjizi, Belma; Cogun, FerahHuman luteinizing hormone (LH) is an important analyte for doping control analysis since it increases the athletic performance. However, traditional methods to detect LH have few disadvantages, such as long analysis duration, waste disposal problem and sample matrix effect. Addressing these problems, surface enhanced Raman spectroscopy based LH analysis using a passive microfluidic chip was developed and optimized. Antibody modified magnetic gold nanoparticles captured the LH and then, 4-aminothiophenol (4-ATP) labeled nanoparticles formed the sandwich immunoassay structure. The complex and the other reactions occurred in different chambers of the chip. The SERS signals of 4-ATP were recorded from the chamber and the system was shown to detect 0.036 IU L-1 in serum samples. The performance of the immunoassay was compared to all other methods and the proposed assay was the fastest analysis of LH without any problems associated with the sensitivity. The shorter analysis time was recorded because the chip enables the control of all reactions in one place and there was no requirement of a specialized laboratory. (c) 2018 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 21Citation - Scopus: 25Effect of Electrical Discharge Machining on Dental Y-Tzp Ceramic-Resin Bonding(Elsevier Ireland Ltd, 2017) Kucukturk, Gokhan; Gurun, Hakan; Cogun, Can; Esen, Ziya; Rona, Nergiz; Yenisey, MuratPurpose: The study determined (i) the effects of electrical discharge machining (EDM) on the shear-bond strength (SBS) of the bond between luting resin and zirconia ceramic and (ii) zirconia ceramic's flexural strength with the three-point bending (TPB) test. Methods: Sixty 4.8 mm x 4.8 mm x 3.2 mm zirconia specimens were fabricated and divided into four groups (n = 15): SBG: sandblasted + silane, TSCG: tribochemical silica coated + silane, LTG: Er:YAG laser treated + silane, EDMG: EDM + silane. The specimens were then bonded to a composite block with a dual-cure resin cement and thermal cycled (6000 times) prior to SBS testing. The SBS tests were performed in a universal testing machine. The SBS values were statistically analyzed using ANOVA and Tukey's test. To determine flexural strength, sixty zirconia specimens were prepared and assigned to the same groups (n = 15) mentioned earlier. After surface treatment TPB tests were performed in a universal testing machine (ISO 6872). The flexural strength values were statistically analyzed using ANOVA and Tukey's test (a = 0.05). Results: The bond strengths for the four test groups (mean SD; MPa) were as follows: SBG (Control), 12.73 +/- 3.41, TSCG, 14.99 +/- 3.14, LTG, 7.93 +/- 2.07, EDMG, 17.05 +/- 2.71. The bond strength of the EDMG was significantly higher than those of the SBG and LTG (p < 0.01). The average flexural strength values for the groups SBG (Control), TSCG, LTG and EDMG were 809.47, 800.47, 679.19 and 695.71 MPa, respectively (p > 0.05). Conclusions: The EDM process improved the SBS. In addition, there was no significant adverse effect of EDM on the flexural strength of zirconia. (C) 2016 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.Article Citation - WoS: 191Citation - Scopus: 228An Experimental Investigation on the Impact Response of Composite Materials(Pergamon-elsevier Science Ltd, 2012) Gulgec, Mufit; Evci, CelalDue to the improved impact performance characteristics, composites are widely used in engineering and military applications to absorb the impact energy. Determination of impact response of composite materials provides the engineer and the manufacturer with critical knowledge to understand the failure criteria, initiation of the first failure and damage growth through the laminates. This study covers the investigation of impact damage growth and determination of Hertzian failure and maximum force thresholds in three different types of composites. Unidirectional E-Glass, woven E-Glass and woven Aramid composite samples with dimensions of 100 x 100 mm are subjected to low velocity impact with an instrumented impact test system. Rebound, on-set of perforation and perforation limits of composites are found out. Also, energy profile diagrams of both unidirectional and plain weave E-Glass composites are obtained. According to test results, woven composites are found to be superior to unidirectional composites in the protection limit of low velocity impact. It is also observed that damage growth in woven composites is restricted within a smaller area. Impact tests conclude that strength of the composite materials under dynamic loading increases considerably compared to static loading case as a result of strain rate sensitivity. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 17Distributed Real-Time Protocols for Industrial Control Systems: Framework and Examples(Ieee Computer Soc, 2012) Schmidt, Klaus Werner; Schmidt, Ece GuranThe automation of today's large-scale industrial systems relies on the operation of distributed controller devices that perform local computations and exchange information via communication networks. The subject of this paper is the development of a family of shared-medium industrial communication protocols that support the transmission of real-time (RT) and nonreal-time (nRT) data among distributed controller devices. Different from existing protocols, we suggest to incorporate information that is available from the control application in the protocol definition. As a result, our protocols dynamically change the bandwidth allocation on the shared medium according to the instantaneous communication requirements while ensuring hard RT guarantees. Following the recent developments in industrial automation, our protocols can be realized as software layers on top of low-cost conventional Ethernet.Article Citation - WoS: 9Citation - Scopus: 9Efficient Abstractions for the Supervisory Control of Modular Discrete Event Systems(Ieee-inst Electrical Electronics Engineers inc, 2012) Schmidt, Klaus Werner; Ribeiro Cury, Jose Eduardo; Cury, José Eduardo RibeiroThe topic of this technical note is the nonblocking and maximally permissive abstraction-based supervisory control for modular discrete event systems (DES). It is shown, that an efficient abstraction technique, that was developed for the nonconflict verification of modular DES, is also suitable for the nonblocking supervisory control. Moreover, it is proved that this abstraction technique can be extended by the condition of local control consistency, in order to achieve maximally permissive supervision. Different from existing approaches, the presented abstraction does not require to preserve the shared events among the system components in the respective abstraction alphabets, and hence leads to potentially smaller system abstractions. The obtained results are illustrated by a flexible manufacturing system example.Article Citation - WoS: 16Citation - Scopus: 18Verification of Modular Diagnosability With Local Specifications for Discrete-Event Systems(Ieee-inst Electrical Electronics Engineers inc, 2013) Schmidt, Klaus WernerIn this paper, we study the diagnosability verification for modular discrete-event systems (DESs), i.e., DESs that are composed of multiple components. We focus on a particular modular architecture, where each fault in the system must be uniquely identified by the modular component where it occurs and solely based on event observations of that component. Hence, all diagnostic computations for faults to be detected in this architecture can be performed locally on the respective modular component, and the obtained diagnosis information is only relevant for that component. We define the condition of modular language diagnosability with local specifications (MDLS) in order to capture that each fault can indeed be detected in this modular architecture. Then, we show that MDLS can be formulated as a specific language-diagnosability problem. As the main contribution of this paper, we develop an incremental abstraction-based approach for the verification of MDLS, which is based on projections that fulfill the loop-preserving observer condition. In particular, our approach efficiently avoids the construction of a global system model, which is infeasible for systems of realistic size. Furthermore, we do not rely on the assumption of a live global plant, which is prevalent in previous diagnosability methods for modular DESs. We illustrate our approach and its computational savings by a manufacturing system example.