1,722,381 research outputs found
Simple, Reliable, Scalable and Energy Efficient Wireless Sensor Networks
No full textWireless communication and networking technology has facilitated people to be connected with each other closely. Cellular network is evolving now from the third generation to the fourth generation. In the meanwhile we are experiencing the demand for wireless networks which can facilitate the communication between humans and environment, human and machines or even machine and machine. Such networks will help us know more about our surroundings which could lead us towards a better and greener life. Wireless Sensor Networks (WSN) is one candidate among such networks. It turns sensing tasks from small scale, centralized and expensive to large scale, distributed and low-cost by connecting small battery powered sensors with wireless links. We start the thesis by introducing WSN, its background and current status in Chapter 1. Although a lot of work has been reported in the literature on WSN, there are still many challenges. In this thesis, we focus on five of them, namely, (1)energy, (2)reliability, (3)scalability, (4)ease of use and (5)ease of set up. Energy is a challenge since WSNs are powered by batteries or even energy harvested from the ambience. The second, fourth and the fifth challenges are the hindrance in the way of high adaptation of WSNs while the third one will challenge when WSNs are largely deployed. Motivations and contributions of the thesis are also presented in the first chapter. Chapter 2 gives an overview of the literature in the several categories, such as physical layer, MAC layer, networking layer, synchronization and real deployment. Our work in the rest of the thesis is related to the work introduced in this chapter. We present the first result of our research in Chapter 3, which focuses on energy and reliability challenge on link layer. To improve the reliability of a link, we have to know the quality of the link. Thus we firstly analyze and try to improve link quality estimation methods in the chapter. We propose a new method for the estimation of packet delivery ratio which balances estimation accuracy and the overhead it causes. Then Minimum Energy Packet Forwarding (MEPF) protocol is proposed with the purpose of delivering a packet reliable with least amount of energy. MEPF tries to achieve the objective by tuning transmission power online for each packet with respect to the link quality. If a packet is lost, MEPF retransmits it smartly only when the link is considered to be good enough. Experimental results prove that MEPF uses almost the lowest possible transmission power without increasing the packet loss and retransmits a lost packet only once to eventually deliver it. We move a layer up from MAC to the network layer in Chapter 4. We organize a network into a better topology to improve energy efficiency and scalability. Two types of topologies are considered in this chapter, flat and clustered. In the former one each node has the same role while in the latter one nodes are organized into clusters where a node is either a Cluster Head (CH) or a Cluster Member (CM). We firstly analyze why a clustered topology may save energy then we quantify the saving. Since traffic is reduced in a clustered network, less contention or collision is expected and more nodes can communicate simultaneously. Thus a clustered network is highly scalable. To form a cluster topology from a flat one, we propose a cluster forming protocol which selects least amount of CHs which have the highest remaining energy. Thus they can live longer under higher traffic load compared to CMs. Simulation results show the feasibility and performance of the proposed protocol. Chapter 5 improves accuracy of localization, one of the most important WSN applications. One reason for the low accuracy is that the radio coverage of small and inexpensive antennas on sensor nodes, especially those in a Body Area Sensor Networks (BASN), is not omnidirectional. This problem leads to the failure of many localization protocols to achieve good accuracy since they are based on the assumption of omnidirectional antennas. In the chapter we proposed to use multiple receivers to locate a person in the context of a BASN. This method improves localization accuracy from a single receiver by mitigating the errors caused by varied and non-uniform beamwidth of antennas and combating fading with spatial diversity. We test this method in two classes of localization methods. The outcome of experimental results show that the method achieves a higher accuracy than a single receiver. Thus the reliability of localization is improved. Setting up a WSN especially for experiments is cumbersome and time-consuming process. It impacts the ease of use and set up. Thus we propose a framework for flexible and low-cost testbed in Chapter 6. Such a testbed only has sensor motes. Other than experiments, testbed management such as downloading the experimental code, reprogramming, testbed control, logging and collecting experimental results and synchronization are all carried out by the sensor motes wirelessly without extra devices. Thus a low-cost testbed can be set up quickly. A case study which realizes components in the framework is also presented. Finally the results of the thesis are summarized in Chapter 7. Future work is also presented there.TelecommunicationElectrical Engineering, Mathematics and Computer Scienc
sj-docx-1-psp-10.1177_01461672231218047 – Supplemental material for New Wine in an Old Bottle? Exposure to Bullying-Related Media and Bullying Perpetration Behavior in Daily Life Among Adolescents
No full textSupplemental material, sj-docx-1-psp-10.1177_01461672231218047 for New Wine in an Old Bottle? Exposure to Bullying-Related Media and Bullying Perpetration Behavior in Daily Life Among Adolescents by Zhaojun Teng, Qian Nie, Meg Stomski, Chuanjun Liu and Cheng Guo in Personality and Social Psychology Bulletin</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Appendix A -Supplemental material for Optimization of carbamylation conditions and study on the effects on the product ions of carbamylation and dual modification of the peptide by Q-TOF MS
No full textSupplemental material, Appendix A for Optimization of carbamylation conditions and study on the effects on the product ions of carbamylation and dual modification of the peptide by Q-TOF MS by Cheng Guo, Xuefeng Guo, Lei Zhao, Dandan Chen, Jin Wang and Jia Sun in European Journal of Mass Spectrometry</p
Variations on the Author
Full text link“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
Supplemental material for this article is available online.
No full textSupplemental Material for Longitudinal Link Between Bullying Victimization and Bullying Perpetration: A Multilevel Moderation Analysis of Perceived School Climate by Qian Nie, Chunyan Yang, Meg Stomski, Zhanfeng Zhao, Zhaojun Teng and Cheng Guo, in Journal of Interpersonal Violence</p
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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