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Permanent URI for this communityhttps://hdl.handle.net/20.500.14288/2
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Publication Metadata only A fundamental experimental approach for optimal design of speed bumps(Elsevier, 2018) Bilgin, Ertuğrul; Lav, Abdullah Hilmi; N/A; Lav, Ahmet Hakan; Undergraduate student; School of MedicineSpeed bumps and humps are utilized as means of calming traffic and controlling vehicular speed. Needless to say, bumps and humps of large dimensions in length and width force drivers to significantly reduce their driving speeds so as to avoid significant vehicle vertical acceleration. It is thus that this experimental study was conducted with the aim of determining a speed bump design that performs optimally when leading drivers to reduce the speed of their vehicles to safe levels. The first step of the investigation starts off by considering the following question: "What is the optimal design of a speed bump that will - at the same time - reduce the velocity of an incoming vehicle significantly and to a speed that resulting vertical acceleration does not jeopardize road safety? The experiment has been designed to study the dependent variables and collect data in order to propose an optimal design for a speed bump. To achieve this, a scaled model of 1:6 to real life was created to simulate the interaction between a car wheel and a speed bump. During the course of the experiment, a wheel was accelerated down an inclined plane onto a horizontal plane of motion where it was allowed to collide with a speed bump. The speed of the wheel and the vertical acceleration at the speed bump were captured by means of a Vernier Motion Detector.Publication Open Access Hub location, routing, and route dimensioning: strategic and tactical intermodal transportation hub network design(The Institute for Operations Research and the Management Sciences (INFORMS), 2021) Yaman Hande; Karaşan Oya Ekin; Department of Industrial Engineering; Yıldız, Barış; Faculty Member; Department of Industrial Engineering; College of Engineering; 258791We propose a novel hub location model that jointly eliminates some of the traditional assumptions on the structure of the network and on the discount as a result of economies of scale in an effort to better reflect real-world logistics and transportation systems. Our model extends the hub literature in various facets: instead of connecting nonhub nodes directly to hub nodes, we consider routes with stopovers; instead of connecting pairs of hubs directly, we design routes that can visit several hub nodes; rather than dimensioning pairwise connections, we dimension routes of vehicles; and rather than working with a homogeneous fleet, we use intermodal transportation. Decisions pertinent to strategic and tactical hub location and transportation network design are concurrently made through the proposed optimization scheme. An effective branch-and-cut algorithm is developed to solve realistically sized problem instances and to provide managerial insights.Publication Metadata only Multihop-cluster-based IEEE 802.11p and LTE hybrid architecture for VANET safety message dissemination(Institute of Electrical and Electronics Engineers (IEEE), 2016) N/A; N/A; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Uçar, Seyhan; Ergen, Sinem Çöleri; Özkasap, Öznur; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 7211; 113507Several vehicular ad hoc network (VANET) studies have focused on communication methods based on IEEE 802.11p, which forms the standard for wireless access for vehicular environments. In networks employing IEEE 802.11p only, the broadcast storm and disconnected network problems at high and low vehicle densities, respectively, degrade the delay and delivery ratio of safety message dissemination. Recently, as an alternative to the IEEE 802.11p-based VANET, the usage of cellular technologies has been investigated due to their low latency and wide-range communication. However, a pure cellular-based VANET communication is not feasible due to the high cost of communication between the vehicles and the base stations and the high number of handoff occurrences at the base station, considering the high mobility of the vehicles. This paper proposes a hybrid architecture, namely, VMaSC-LTE, combining IEEE 802.11p-based multihop clustering and the fourth-generation (4G) cellular system, i.e., Long-Term Evolution (LTE), with the goal of achieving a high data packet delivery ratio (DPDR) and low delay while keeping the usage of the cellular architecture at a minimum level. In VMaSC-LTE, vehicles are clustered based on a novel approach named Vehicular Multihop algorithm for Stable Clustering (VMaSC). The features of VMaSC are cluster head (CH) selection using the relative mobility metric calculated as the average relative speed with respect to the neighboring vehicles, cluster connection with minimum overhead by introducing a direct connection to the neighbor that is already a head or a member of a cluster instead of connecting to the CH in multiple hops, disseminating cluster member information within periodic hello packets, reactive clustering to maintain the cluster structure without excessive consumption of network resources, and efficient size-and hop-limited cluster merging mechanism based on the exchange of cluster information among CHs. These features decrease the number of CHs while increasing their stability, therefore minimizing the usage of the cellular architecture. From the clustered topology, elected CHs operate as dual-interface nodes with the functionality of the IEEE 802.11p and LTE interface to link the VANET to the LTE network. Using various key metrics of interest, including DPDR, delay, control overhead, and clustering stability, we demonstrate the superior performance of the proposed architecture compared with both previously proposed hybrid architectures and alternative routing mechanisms, including flooding and cluster-based routing via extensive simulations in ns-3 with the vehicle mobility input from the Simulation of Urban Mobility. The proposed architecture also allows achieving higher required reliability of the application quantified by the DPDR at the cost of higher LTE usage measured by the number of CHs in the network.Publication Metadata only On the reliability analysis of C-V2X Mode 4 for next generation connected vehicle applications(Institute of Electrical and Electronics Engineers (IEEE), 2022) Karaağaç, Sercan; N/A; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Reyhanoğlu, Aslıhan; Kar, Emrah; Kümeç, Feyzi Ege; Kara, Yahya Şükür Can; Turan, Buğra; Ergen, Sinem Çöleri; Researcher; Researcher; Researcher; Researcher; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; N/A; N/A; N/A; N/A; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; N/A; 7211Vehicle-to-Everything Communication (V2X) technologies are provisioned to play an important role in increasing road safety by enabling advanced connected vehicle applications such as cooperative perception, cooperative driving, and remote driving. However, the reliability of the technology is limited mainly due to wireless communication channel characteristics. Therefore, investigation of V2X reliability aspects is crucial to utilize the technology efficiently. In this paper, we provide simulation and measurement-based reliability analysis of Cellular Vehicle-to-Everything (C-V2X) Mode 4 technology for various message sizes and Modulation and Coding Schemes (MCS) selections. We demonstrate that the Packet Delivery Ratio (PDR), a key communication performance metric, heavily depends on message size and selected MCS.