1,720,956 research outputs found
Performance comparison in Ultra Wide Band positioning in sensor networks: least square minimization versus grid search approach
No full textThe localization task in sensor networks is partic-ularly critical whenever the sensor measurements are position-related, as in case of thermal and electromagnetic quantities. The deployment of a sensor network often requires the usage of low-cost devices able to achieve acceptable measurement accuracy and having the need to retrieve fast and accurate positioning information. In such networks, the localization task is generally performed by a special node coordinating the network. Nevertheless, its computing power is often limited. To this aim, in this paper we compare two different positioning techniques (least square minimization, grid search), to be applied in Ultra- Wide-Band positioning scheme, from the accuracy point of view and computing time required for accomplishing the task. They differ in working principle, needed a priori information, localization resolution and time to completion parameter. According to the available resources, the adoption of one of them should be prefer-able to the other one. Obtained results prove the goodness of both methods, specifically ranking them by application purposes. The paper is intended to give the designers an extensive analysis to evaluate pros and cons to adopt a completely blind positioning technique, namely the least square minimization, versus a more informed and constrained system, as the grid search case
UWB-Based Indoor Localization: How to Optimally Design the Operating Setup?
Full text linkLocalizing objects in indoor environments with anchor-based systems poses several challenges to be faced. The main one is the design phase. What is the minimum number of anchors to be adopted? What is the optimal placement of the anchors in the operating domain? These are typical issues that need to be solved in this stage. Such issue is generally addressed by several experimental tests, imposing high costs both in the required large amounts of time and in the use of devices. In addition, sometimes the experiments will not warrant to identify the optimal design solution. In this work, a black-box design tool is proposed, able to manage different environments, in terms of domain size, maximum number of available anchors, device metrological features, and target performance. Such an approach, to be effective, needs a preliminary validation versus experimental results to make the future performance predictions reliable and avoid unexpected localization accuracy degradation. For this reason, the presented work adopts a side-by-side development, by evaluating results' compatibility, in static and dynamic contexts, before addressing further and more complex analyses relying on the design tool only. Such a comparison proves the goodness of the developed design tool, and the outcomes allow an accurate localization system design by finding anchors' placement solutions with the minimum computational burden
A UWB-based localization system: Analysis of the effect of anchor positions and robustness enhancement in indoor environments
No full textLocalization in indoor environments is a hard task because of several constraints, both in terms of multiple reflections due to wall and people moving around the localization domain. This is especially due to the communication technologies adopted to perform both ranging and positioning. In this paper, a Ultra Wide Band technology is adopted to perform localization in indoor environment, considering a square domain, by means of three fixed anchors and one mobile node. In specific applications, the object to localize is covered by a metallic shield, e.g, robots, and the localization sensor must be embedded inside the object. In this scenario, the paper proposes to solve three issues: assess nominal performance of UWB localization technology, find a way to approach it in harsh conditions, as the one above specified and a further investigation on optimal anchors' positions in the localization domain to verify sensitivity to specific set-up arrangement. First task is accomplished through an extensive measurement campaign without any obstacle; second one is solved by means of a double calibration procedure estimating anchor-to-anchor distance and online correcting the acquired data. A simulated approach that, starting from on-field measurements, verifies the role of different anchors' positions on the positioning error, completes the investigation
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
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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