1,720,988 research outputs found
Optimal Operation Mode Selection for Energy-Efficient Light-Weight Multi-Hop Time Synchronization in Linear Wireless Sensor Networks
No full textKara, Ali/0000-0002-9739-7619; Tavli, Bulent/0000-0002-9615-1983; tavli, bulent/0000-0002-9615-1983We explored the joint effect of synchronization window and offset/drift mode selection on the time synchronization of linear wireless sensor networks (LWSNs). Recent advances in the field along with the availability of capable hardware led to adoption of LWSNs in diverse areas like monitoring of roads, pipelines, and tunnels. The linear topology applications are susceptible to single point of failure; therefore, energy efficient operation of LWSNs is even more important than the traditional WSNs. To address the challenge, we investigate the time synchronization mode selection for the optimum operation of a multi-hop and low-overhead LWSN. We investigate two modes of synchronization: synchronization by using only offset and synchronization by using offset in addition to the clock drift. Furthermore, we investigate the effects of synchronization window size. Our experimental results reveal that computation of offset alone for smaller window sizes and resynchronization periods is sufficient in achieving acceptable degree of synchronization
Optimal Energy Efficient Routing in Wireless Sensor Networks With Link Asymmetry
No full textTavli, Bulent/0000-0002-9615-1983; Koyuncu, Murat/0000-0003-1958-5945In 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 Proceedings Citation Index - Scienc
Backhaul-Aware Optimization of Uav Base Station Location and Bandwidth Allocation for Profit Maximization
No full texttavli, bulent/0000-0002-9615-1983; Tavli, Bulent/0000-0002-9615-1983; Yanikomeroglu, Halim/0000-0003-4776-9354; Cicek, Cihan Tugrul/0000-0002-3532-2638; Gultekin, Hakan/0000-0002-5416-3249Unmanned Aerial Vehicle Base Stations (UAV-BSs) are envisioned to be an integral component of the next generation Wireless Communications Networks (WCNs) with a potential to create opportunities for enhancing the capacity of the network by dynamically moving the supply towards the demand while facilitating the services that cannot be provided via other means efficiently. A significant drawback of the state-of-the-art have been designing a WCN in which the service-oriented performance measures (e.g., throughput) are optimized without considering different relevant decisions such as determining the location and allocating the resources, jointly. In this study, we address the UAV-BS location and bandwidth allocation problems together to optimize the total network profit. In particular, a Mixed-Integer Non-Linear Programming (MINLP) formulation is developed, in which the location of a single UAV-BS and bandwidth allocations to users are jointly determined. The objective is to maximize the total profit without exceeding the backhaul and access capacities. The profit gained from a specific user is assumed to be a piecewise-linear function of the provided data rate level, where higher data rate levels would yield higher profit. Due to high complexity of the MINLP, we propose an efficient heuristic algorithm with lower computational complexity. We show that, when the UAV-BS location is determined, the resource allocation problem can be reduced to a Multidimensional Binary Knapsack Problem (MBKP), which can be solved in pseudo-polynomial time. To exploit this structure, the optimal bandwidth allocations are determined by solving several MBKPs in a search algorithm. We test the performance of our algorithm with two heuristics and with the MINLP model solved by a commercial solver. Our numerical results show that the proposed algorithm outperforms the alternative solution approaches and would be a promising tool to improve the total network profit.Scientific and Technological Research Council of Turkey (TUBITAK) under 2211 Ph.D. ScholarshipThis work was supported in part by the Scientific and Technological Research Council of Turkey (TUBITAK) under 2211 Ph.D. Scholarship
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Social Internet of Digital Twins via Distributed Ledger Technologies: Application of Predictive Maintenance
No full textPredictive Maintenance in the era of Internet-of-Things is envisioned to he an important functionality of consumer electronics along with many other application areas. Challenges for Predictive Maintenance within Internet of-Things ecosystem include heterogeneity, scalability, identification, constrained resources, mobility, security, and privacy. In this paper, we propose a reference model for Predictive Maintenance of commercial appliances, the digital twins of which interact socially via Distributed Ledger Technologies
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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