1,720,961 research outputs found
An analytical hierarchy process-based approach to solve the multi-objective multiple traveling salesman problem
No full textWe consider the problem of assigning a team of autonomous robots to target locations in the context of a disaster management scenario while optimizing several objectives. This problem can be cast as a multiple traveling salesman problem, where several robots must visit designated locations. This paper provides an analytical hierarchy process (AHP)-based approach to this problem, while minimizing three objectives: the total traveled distance, the maximum tour, and the deviation rate. The AHP-based approach involves three phases. In the first phase, we use the AHP process to define a specific weight for each objective. The second phase consists in allocating the available targets, wherein we define and use three approaches: market-based, robot and task mean allocation-based, and balanced-based. Finally, the third phase involves the improvement in the solutions generated in the second phas
A Mobile Gnutella-based Network System to Support the Distributed Collaborative Virtual Environment
No full textCollaborative Virtual Environments (CVEs), such as military training simulations, emergency preparedness exercises, and online games have made a considerable impact on both commercial and academic fields over the last few years. Due to the rapidly increasing usage of personal mobile devices and the need of executing CVE applications in environments that have no previous network infrastructure, Mobile Collaborative Virtual Environments (MCVEs) will become ubiquitous in the future. In such systems, users will share a 3D virtual environment through their mobile devices in an ad-hoc network (MANET) in order to accomplish specific missions. We aspire to develop and deploy CVEs over MANETs using the peer-to-peer model. Both peer-to-peer networks and MANETs exhibit the same features; which include complete decentralization, self-configuration, and self-healing. However, peer-to-peer networks and MANETs operate on different network layers, and may introduce poor performance. Mobile ad-hoc and peer-to-peer networks drive the future of CVEs, and thus form the foundation for this thesis.
Most existing CVE systems are tuned to specific tasks, and their architectures are typically tightly coupled with wired networks and desktop settings, therefore they are not adequate enough for addressing mobile collaborative virtual environments. The evolutionary step in MCVE applications is handling the mobility effect in all its forms, and tackling the poor performance of the ad-hoc network. In this thesis, we explain the main networking issues involved in building scalable MCVEs, and review the most well-known CVE and peer-to-peer systems. We then present a mobility-aware cross-layer approach for MCVE applications; this approach relies on building a dynamic multi-tier overlay network architecture-based Gnutella network. The proposed overlay network will manage mobile devices using a novel rule-based discovery technique, in which users are discovered by their virtual environment interest and proximity. With the help of a caching mechanism and a Gnutella Ultrapeer System to perform a dynamic Ultrapeer selection, we were able to outperform traditional mobile overlay networks, as shown in our simulation results
Design and implementation of visualization techniques for subsumption hierarchies
Full text linkData Visualizing is becoming an important research topic in computer science, and has received considerable attention in the last two decades. In several instances, visualization is a crucial step in order to easily access and properly understand the data. With it, the analysis and the decision making is a relatively easier task. In this thesis, we will focus on the visualization of the concept hierarchies by producing several geometric representations. The main tools used are the graphs where the concepts are represented by vertices and the edges represent the relationships between concepts. Our specific application is the development of a drawing system that interfaces with the description logic reasonner RACER . Unless there is no error in the ontology, the RACER system responds to the taxonomy queries correctly. The body of the response must contain information about a relational structure called a concept hierarchy. This information could be saved as a text file. In the first part of the thesis, we will present our system architecture and discuss its components then we will show how to collect the information about the concept hierarchy using the taxonomy query. We also describe methods for parsing hierarchies and the creation of an appropriate data structure that will be used by the set of algorithms we developed. The second part of the thesis contains the algorithms used to retrieve the properties of the concept hierarchy, as well as to study the specific structure of these hierarchies. It is well known that graph drawing in general is a very complex issue and, therefore, it is important that our approach in drawing takes into account the specificity of these graphs. We consider many aesthetic criteria that fit our specific application: the levels should be kept together as much as possible, the drawing area should be as small as possible, the number of crossings should be minimized, etc. Also, we will develop a decomposition technique that will be very useful in many instances
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
Game Engine Solutions
No full textThe rapid development of hardware and system platforms provides a favorable foundation for game development. A game engine overview is introduced first. Then, key features and available solutions of game engines are discussed. Typical products of game engines are shown and evaluated. Finally, we summarize our findings
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