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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Model to Convert Airport Geographic and Geometric Information into a Node-Link Network

Zhang, Yang 17 January 2015 (has links)
An airport node-link network model is an important input for most airport simulation models. Developing, maintaining and updating detailed airport surface node-link models require significant work. A model to convert airport geographic and geometric information into a node-link network is thus needed. In this thesis, an efficient model to automate the procedure of converting airport geographic and geometric information into a node-link network is proposed. The geographic and geometric information are obtained from the Aeronautical Information Exchange Model (AIXM). The node-link network is generated by converting the geographic and geometric information contained into the AIXM files using coincident geometry management and polygon representation development. Finally, using the airport node-link network generation model, a standalone computer application, called Taxiway Toolkit, is developed to improve the Airfield Delay Simulation Model (ADSIM+). / Master of Science
2

Visualization of Feature Dependency Structures : A case study at Scania CV AB / Visualisering av regelverk för beroenden mellan produktegenskaper : En fallstudie på Scania CV AB

Bronge, Erica January 2017 (has links)
As many automotive companies have moved towards a higher degree of variability in the product lines they offer their customers, a necessary need has emerged for so called feature dependency structures that are used to describe product feature dependencies and verify order validity. In this study, the possibility of using a node-link graph representation to visualize such a feature dependency structure and the associated affordances and limitations were investigated by the implementation of a case study at the Swedish automotive company Scania CV AB. Qualitative data gathering methods such as contextual inquiry and semi-structured interviews with employees were used to identify key tasks and issues involved in maintenance and analysis of Scania’s in-house feature dependency structure. These findings were used together with user-supported iterative prototyping to create a few visualization prototypes intended to provide support with performance of some of the identified tasks. User evaluation of the prototypes showed that a node-link graph representation was a viable solution to support users with structure maintenance, exhibiting the following affordances: structure exploration, overview and context. Furthermore, the major limitations of the tested representation were found to be lookup of specific information and access to detail. The findings of this study are expected to be of use for other automotive companies that employ a high degree of feature variability in their product lines through the use of complex feature dependency structures. / I samband med att flera fordonstillverkare gått över till att erbjuda en allt större grad av varians i de produktlinjer man erbjuder sina kunder så har ett nödvändigt behov uppstått av att ha regelverk som beskriver de beroenden som finns mellan produktegenskaper och verifierar att inkomna ordrar är giltiga. I den här studien så har möjligheten att visualisera den typen av regelverk med en så kallad ”node-link”-graf samt de styrkor och svagheter som följer med en sådan representation undersökts genom en fallstudie på den svenska fordonstillverkaren Scania CV AB. Med hjälp av kvalitativa datainsamlingsmetoder som så kallad ”Contextual inquiry” och semistrukturerade intervjuer med anställda specialiserade på underhåll av Scanias egna egenskapsregelverk så kunde nyckeluppgifter och svårigheter relaterade till regelverket identifieras. Dessa upptäckter användes sedan tillsammans med användarcentrerat iterativt prototypande för att skapa ett antal visualiseringsprototyper avsedda att underlätta utförandet av några av de tidigare identifierade uppgifterna. Användarutvärdering av prototyperna visade att en visualisering baserad på en ”node-link”-representation var en gångbar lösning som kunde underlätta för användarna. Dess styrkor var att stödja utforskande av strukturen med bra överblick av innehållet och bibehållet sammanhang. Representation var dock svag när det gällde att stödja användaren i att leta upp specifik information och att tillhandahålla mer ingående detaljer. Dessa resultat förväntas vara användbara för andra fordonstillverkare som bygger sina produktlinjer på en hög grad av varians med hjälp av komplexa beroenderegelverk för produktegenskaper.
3

基於臉書互動行為的關係圖領域專屬語言與工具 / A Domain Specific Language for Describing Facebook Interaction Graphs

潘宗佐, Pan, Tsung Tso Unknown Date (has links)
因大量臉書用戶留下不少行為紀錄,吸引研究人員蒐集臉書資料,從中挖掘具有價值的潛在資訊與研究成果,並用 Graph 點線關係圖視覺化呈現成果。然而透過臉書 Graph API 蒐集資料的方法,自 2.0 版起漸漸提高了限速限制,造成蒐集資料開始是一個問題。雖有研者人員提出應對方法,卻也產生用戶識別度弱化問題。故本研究動機是提出一套工具能有效協助研究人員進行臉書資料蒐集與建立關係圖以利進行分析與研究,在進行相關臉書蒐集資料與社會網絡與社群網絡分析文獻探討後,實作一種基於爬蟲技術,蒐集具用戶識別度之臉書資料;以及提出描述臉書互動行為的關係圖領域專屬語言;實作對應之使用者操作介面工具,讓使用者透過圖形化操作方式描述定義臉書粉絲頁、使用者、Hashtag、留言及回覆與貼文之間互動行為建立關係圖。經過本研究實驗設計與驗證,證明蒐集資料具識別度、產生的關係圖是正確以及問卷調查指出 75% 受試人員認同本系統可快速建立關係圖。未來可以結合爬蟲與關係圖領域專屬語言線上即時建立關係圖,以及導入更多社群分析功能,以利研究人員可以在本系統上進行更深入的分析與研究。 / The huge amount of digital footprints of Facebook users have become a good research resource and we have seen many good results developed by collecting data from Facebook and visualizing it to node-link diagram. However, there are more and more rate limits in Facebook Graph API since version 2.0. Although one could overcome the restriction of rate limits by creating more Facebook App resources, yet this makes user identification become cumbersome in analyzing the retrieved data. Therefore, the motivation of this research is to provide a set of tools to assist researchers in collecting recognizable Facebook user data with a crawler and propose a domain specific language (DSL) to build the relation graph by describing Facebook interactions. With our crawler and the DSL tool, we are able to gather unique user data successfully. The experimental results show that we can construct node-link diagram conveniently, and 75% of the surveyed subjects agreed that our tool could be helpful for building graph.
4

Node-Link Mapping and Rational Recovery: Enhancing the Recovery Process

Schmidt, Eric A. (Eric Alexander) 08 1900 (has links)
Alcoholics Anonymous (AA) continues to be the most accepted approach for the treatment of addictions in the United States. However, due to recent evidence questioning the effectiveness of AA, the need for alternative approaches to the treatment of addictions has become clear. The following research addresses the efficacy of one such alternative, Rational Recovery (RR). Node-Link Mapping (NLM), a graphic communication technique which uses links and nodes as building blocs to facilitate and enhance communication of information as well as awareness in a counseling environment, was implemented to enhance the recovery process. Three groups of ten (10), chemically dependent, adjudicated subjects were exposed to three different treatment approaches at an outpatient counseling center. The Experimental group received RR with NLM, the Comparison group was exposed only to RR, and the Control group continued in treatment according to the protocol of the counseling agency. All subjects were given the Substance Abuse Subtle Screening Inventory-2 (SASSI-2) as a measurement of symptoms associated with chemical dependency. The subjects were also administered the Rotter Internal-External Locus of Control Scale (Rotter I-E Scale) to determine locus of control prior to treatment and any change after treatment.
5

Supporting the design of custom static node-ling graph visualization / Permitindo o design de visualização nodo aresta de graof esataticos personalizados

Spritzer, Andre Suslik January 2015 (has links)
Visualizações de grafos para comunicação aparecem numa variedade de contextos que vão do acadêmico-científico até o jornalístico e até mesmo artístico. Diferente de visualizações de grafos para exploração e análise de dados, essas imagens são usadas para “contar uma história” que já se conhece ao invés da “procura de uma nova história” nos dados. Apesar de ser possível usar software para desenho de grafos e edição de diagramas para produzí-las, visualizações feitas dessa forma nem sempre preenchem os requisitos visuais impostos pelos seus contextos de uso. Programas de edição de imagens podem ser usados para fazer as melhorias necessárias, mas nem todas as modificações são possíveis e o processo de editar essas imagens pode exigir muito tempo e esforço. Neste trabalho, apresentamos uma investigação de visualizações nodo-aresta estáticas para comunicação e de como facilitar sua criação. A partir de uma desconstrução dessas imagens, identificando seus elementos essenciais, e analisando como são criadas, derivamos um conjunto de requisitos que ferramentas para a criação dessas visualizações devem preencher. Para verificar o efeito da metodologia na melhora do fluxo de trabalho de designers, com mais poder e flexibilidade, foi concebido e implementado um protótipo chamado GraphCoiffure. Com um foco especial em auxiliar usuários na criação de visualizações para publicação, Graph- Coiffure foi projetado como uma aplicação standalone que seria usada como um passo intermediário entre programas de desenho e edição de grafos e editores gráficos. Ele combina ferramentas para manipulação interativa de layouts com estilização similar a CSS para permitir que usuários criem e editem visualizações nodo-aresta estáticas. Ilustramos o funcionamento de GraphCoiffure com quatro casos de uso: a adaptação do layout de uma visualização para fazê-la funcionar em uma dada página, a reprodução do estilo de uma visualização e sua aplicação em outro grafo, e a criação integral de duas novas visualizações. Para obter feedback sobre GraphCoiffure, conduzimos uma avaliação informal através de entrevistas com três potenciais usuários, que disseram achar que GraphCoiffure beneficiaria seu trabalho. / Graph visualizations for communication appear in a variety of contexts that range from scientific/ academic to journalistic and even artistic. Unlike graph visualizations for exploration and analysis, these images are used to tell a story that is already known rather than to look for a story within the data. Although graph drawing and diagram editing software can be used to produce them, visualizations made this way do not always meet the visual requirements imposed by their context of use. Graphics authoring software can be used to make the necessary improvements, but not all modifications are possible and the process of editing these images may be very time-consuming and labor-intensive. In this work, we present an investigation of static node-link visualizations for communication and how to better support their creation. We began with a deconstruction of these images, breaking them down into their basic elements and analyzing how they are created. From this, we derived a set of requirements that tools aimed at supporting their creation should meet. To verify if taking all of this into account would improve the workflow and bring more flexibility and power to the users, we created our own prototype, which we named GraphCoiffure. With a special emphasis on helping users on creating visualizations for publication, GraphCoiffure was designed as a standalone application that would serve as an intermediary step between graph drawing and editing software and graphics editors. It combines interactive graph layout manipulation tools with CSS-like styling possibilities to let users create and edit static node-link visualizations for communication. We illustrate the use of GraphCoiffure with four use-case scenarios: the adaptation of a visualization’s layout to make it work on a given page, the reproduction of a visualization’s style and its application on another graph, and the creation of two visualizations from scratch. To obtain feedback on GraphCoiffure, we conducted an informal evaluation by interviewing three potential expert users, who found that it could be useful for their work.
6

Supporting the design of custom static node-ling graph visualization / Permitindo o design de visualização nodo aresta de graof esataticos personalizados

Spritzer, Andre Suslik January 2015 (has links)
Visualizações de grafos para comunicação aparecem numa variedade de contextos que vão do acadêmico-científico até o jornalístico e até mesmo artístico. Diferente de visualizações de grafos para exploração e análise de dados, essas imagens são usadas para “contar uma história” que já se conhece ao invés da “procura de uma nova história” nos dados. Apesar de ser possível usar software para desenho de grafos e edição de diagramas para produzí-las, visualizações feitas dessa forma nem sempre preenchem os requisitos visuais impostos pelos seus contextos de uso. Programas de edição de imagens podem ser usados para fazer as melhorias necessárias, mas nem todas as modificações são possíveis e o processo de editar essas imagens pode exigir muito tempo e esforço. Neste trabalho, apresentamos uma investigação de visualizações nodo-aresta estáticas para comunicação e de como facilitar sua criação. A partir de uma desconstrução dessas imagens, identificando seus elementos essenciais, e analisando como são criadas, derivamos um conjunto de requisitos que ferramentas para a criação dessas visualizações devem preencher. Para verificar o efeito da metodologia na melhora do fluxo de trabalho de designers, com mais poder e flexibilidade, foi concebido e implementado um protótipo chamado GraphCoiffure. Com um foco especial em auxiliar usuários na criação de visualizações para publicação, Graph- Coiffure foi projetado como uma aplicação standalone que seria usada como um passo intermediário entre programas de desenho e edição de grafos e editores gráficos. Ele combina ferramentas para manipulação interativa de layouts com estilização similar a CSS para permitir que usuários criem e editem visualizações nodo-aresta estáticas. Ilustramos o funcionamento de GraphCoiffure com quatro casos de uso: a adaptação do layout de uma visualização para fazê-la funcionar em uma dada página, a reprodução do estilo de uma visualização e sua aplicação em outro grafo, e a criação integral de duas novas visualizações. Para obter feedback sobre GraphCoiffure, conduzimos uma avaliação informal através de entrevistas com três potenciais usuários, que disseram achar que GraphCoiffure beneficiaria seu trabalho. / Graph visualizations for communication appear in a variety of contexts that range from scientific/ academic to journalistic and even artistic. Unlike graph visualizations for exploration and analysis, these images are used to tell a story that is already known rather than to look for a story within the data. Although graph drawing and diagram editing software can be used to produce them, visualizations made this way do not always meet the visual requirements imposed by their context of use. Graphics authoring software can be used to make the necessary improvements, but not all modifications are possible and the process of editing these images may be very time-consuming and labor-intensive. In this work, we present an investigation of static node-link visualizations for communication and how to better support their creation. We began with a deconstruction of these images, breaking them down into their basic elements and analyzing how they are created. From this, we derived a set of requirements that tools aimed at supporting their creation should meet. To verify if taking all of this into account would improve the workflow and bring more flexibility and power to the users, we created our own prototype, which we named GraphCoiffure. With a special emphasis on helping users on creating visualizations for publication, GraphCoiffure was designed as a standalone application that would serve as an intermediary step between graph drawing and editing software and graphics editors. It combines interactive graph layout manipulation tools with CSS-like styling possibilities to let users create and edit static node-link visualizations for communication. We illustrate the use of GraphCoiffure with four use-case scenarios: the adaptation of a visualization’s layout to make it work on a given page, the reproduction of a visualization’s style and its application on another graph, and the creation of two visualizations from scratch. To obtain feedback on GraphCoiffure, we conducted an informal evaluation by interviewing three potential expert users, who found that it could be useful for their work.
7

Supporting the design of custom static node-ling graph visualization / Permitindo o design de visualização nodo aresta de graof esataticos personalizados

Spritzer, Andre Suslik January 2015 (has links)
Visualizações de grafos para comunicação aparecem numa variedade de contextos que vão do acadêmico-científico até o jornalístico e até mesmo artístico. Diferente de visualizações de grafos para exploração e análise de dados, essas imagens são usadas para “contar uma história” que já se conhece ao invés da “procura de uma nova história” nos dados. Apesar de ser possível usar software para desenho de grafos e edição de diagramas para produzí-las, visualizações feitas dessa forma nem sempre preenchem os requisitos visuais impostos pelos seus contextos de uso. Programas de edição de imagens podem ser usados para fazer as melhorias necessárias, mas nem todas as modificações são possíveis e o processo de editar essas imagens pode exigir muito tempo e esforço. Neste trabalho, apresentamos uma investigação de visualizações nodo-aresta estáticas para comunicação e de como facilitar sua criação. A partir de uma desconstrução dessas imagens, identificando seus elementos essenciais, e analisando como são criadas, derivamos um conjunto de requisitos que ferramentas para a criação dessas visualizações devem preencher. Para verificar o efeito da metodologia na melhora do fluxo de trabalho de designers, com mais poder e flexibilidade, foi concebido e implementado um protótipo chamado GraphCoiffure. Com um foco especial em auxiliar usuários na criação de visualizações para publicação, Graph- Coiffure foi projetado como uma aplicação standalone que seria usada como um passo intermediário entre programas de desenho e edição de grafos e editores gráficos. Ele combina ferramentas para manipulação interativa de layouts com estilização similar a CSS para permitir que usuários criem e editem visualizações nodo-aresta estáticas. Ilustramos o funcionamento de GraphCoiffure com quatro casos de uso: a adaptação do layout de uma visualização para fazê-la funcionar em uma dada página, a reprodução do estilo de uma visualização e sua aplicação em outro grafo, e a criação integral de duas novas visualizações. Para obter feedback sobre GraphCoiffure, conduzimos uma avaliação informal através de entrevistas com três potenciais usuários, que disseram achar que GraphCoiffure beneficiaria seu trabalho. / Graph visualizations for communication appear in a variety of contexts that range from scientific/ academic to journalistic and even artistic. Unlike graph visualizations for exploration and analysis, these images are used to tell a story that is already known rather than to look for a story within the data. Although graph drawing and diagram editing software can be used to produce them, visualizations made this way do not always meet the visual requirements imposed by their context of use. Graphics authoring software can be used to make the necessary improvements, but not all modifications are possible and the process of editing these images may be very time-consuming and labor-intensive. In this work, we present an investigation of static node-link visualizations for communication and how to better support their creation. We began with a deconstruction of these images, breaking them down into their basic elements and analyzing how they are created. From this, we derived a set of requirements that tools aimed at supporting their creation should meet. To verify if taking all of this into account would improve the workflow and bring more flexibility and power to the users, we created our own prototype, which we named GraphCoiffure. With a special emphasis on helping users on creating visualizations for publication, GraphCoiffure was designed as a standalone application that would serve as an intermediary step between graph drawing and editing software and graphics editors. It combines interactive graph layout manipulation tools with CSS-like styling possibilities to let users create and edit static node-link visualizations for communication. We illustrate the use of GraphCoiffure with four use-case scenarios: the adaptation of a visualization’s layout to make it work on a given page, the reproduction of a visualization’s style and its application on another graph, and the creation of two visualizations from scratch. To obtain feedback on GraphCoiffure, we conducted an informal evaluation by interviewing three potential expert users, who found that it could be useful for their work.
8

Visualizing Logical Architecture of Electrical and Electronic (E/E) Systems in Automotive Industry

Nur, Kazım Gökberk January 2020 (has links)
Modern vehicles equipped with many hardware and software systems. To develop new functionalities and maintain existing features of the vehicles, engineers have to check relationship between software and hardware systems. Due to complexity of these relationships, visual representation of how systems are working together is required to make R&D process easier. At Scania, engineers using node-link diagrams to represent logical function architecture of the Scania vehicles. Logical function architecture is a part of electrical and electronic systems in the automotive industry, due to size of these systems they are considered as a large network. Visualizing large networks by diagrams is not a new problem in literature. At past, researches published about diagram drawing and algorithms have been developed to generate good looking diagram. However, sometimes due to complexity of the data, having complex and unreadable diagrams are unavoidable and they are hard to understand. Previous studies investigated how diagrams should be drawn, however focus was not how users should interact with the diagrams. In node-link diagrams users follows edges to understand relationships between components. Having edges in the diagram heavily affects the diagram drawing time and also required space for the diagram. In this paper I developed an artefact which is not using edges to visualize LFA at Scania. Artefact usability has been tested with Scania engineers by giving some tasks to them. In the tests, artefact without edges achieved better results than node-link diagram and 426% improvement achieved by comparing task completion times in seconds. The artefact proved that it can be powerful alternative to classic node-link diagram visualization.
9

Interactive Visualization Lenses:

Kister, Ulrike 12 June 2018 (has links) (PDF)
Information visualization is an important research field concerned with making sense and inferring knowledge from data collections. Graph visualizations are specific techniques for data representation relevant in diverse application domains among them biology, software-engineering, and business finance. These data visualizations benefit from the display space provided by novel interactive large display environments. However, these environments also cause new challenges and result in new requirements regarding the need for interaction beyond the desktop and according redesign of analysis tools. This thesis focuses on interactive magic lenses, specialized locally applied tools that temporarily manipulate the visualization. These may include magnification of focus regions but also more graph-specific functions such as pulling in neighboring nodes or locally reducing edge clutter. Up to now, these lenses have mostly been used as single-user, single-purpose tools operated by mouse and keyboard. This dissertation presents the extension of magic lenses both in terms of function as well as interaction for large vertical displays. In particular, this thesis contributes several natural interaction designs with magic lenses for the exploration of graph data in node-link visualizations using diverse interaction modalities. This development incorporates flexible switches between lens functions, adjustment of individual lens properties and function parameters, as well as the combination of lenses. It proposes interaction techniques for fluent multi-touch manipulation of lenses, controlling lenses using mobile devices in front of large displays, and a novel concept of body-controlled magic lenses. Functional extensions in addition to these interaction techniques convert the lenses to user-configurable, personal territories with use of alternative interaction styles. To create the foundation for this extension, the dissertation incorporates a comprehensive design space of magic lenses, their function, parameters, and interactions. Additionally, it provides a discussion on increased embodiment in tool and controller design, contributing insights into user position and movement in front of large vertical displays as a result of empirical investigations and evaluations. / Informationsvisualisierung ist ein wichtiges Forschungsfeld, das das Analysieren von Daten unterstützt. Graph-Visualisierungen sind dabei eine spezielle Variante der Datenrepräsentation, deren Nutzen in vielerlei Anwendungsfällen zum Einsatz kommt, u.a. in der Biologie, Softwareentwicklung und Finanzwirtschaft. Diese Datendarstellungen profitieren besonders von großen Displays in neuen Displayumgebungen. Jedoch bringen diese Umgebungen auch neue Herausforderungen mit sich und stellen Anforderungen an Nutzerschnittstellen jenseits der traditionellen Ansätze, die dadurch auch Anpassungen von Analysewerkzeugen erfordern. Diese Dissertation befasst sich mit interaktiven „Magischen Linsen“, spezielle lokal-angewandte Werkzeuge, die temporär die Visualisierung zur Analyse manipulieren. Dabei existieren zum Beispiel Vergrößerungslinsen, aber auch Graph-spezifische Manipulationen, wie das Anziehen von Nachbarknoten oder das Reduzieren von Kantenüberlappungen im lokalen Bereich. Bisher wurden diese Linsen vor allem als Werkzeug für einzelne Nutzer mit sehr spezialisiertem Effekt eingesetzt und per Maus und Tastatur bedient. Die vorliegende Doktorarbeit präsentiert die Erweiterung dieser magischen Linsen, sowohl in Bezug auf die Funktionalität als auch für die Interaktion an großen, vertikalen Displays. Insbesondere trägt diese Dissertation dazu bei, die Exploration von Graphen mit magischen Linsen durch natürliche Interaktion mit unterschiedlichen Modalitäten zu unterstützen. Dabei werden flexible Änderungen der Linsenfunktion, Anpassungen von individuellen Linseneigenschaften und Funktionsparametern, sowie die Kombination unterschiedlicher Linsen ermöglicht. Es werden Interaktionstechniken für die natürliche Manipulation der Linsen durch Multitouch-Interaktion, sowie das Kontrollieren von Linsen durch Mobilgeräte vor einer Displaywand vorgestellt. Außerdem wurde ein neuartiges Konzept körpergesteuerter magischer Linsen entwickelt. Funktionale Erweiterungen in Kombination mit diesen Interaktionskonzepten machen die Linse zu einem vom Nutzer einstellbaren, persönlichen Arbeitsbereich, der zudem alternative Interaktionsstile erlaubt. Als Grundlage für diese Erweiterungen stellt die Dissertation eine umfangreiche analytische Kategorisierung bisheriger Forschungsarbeiten zu magischen Linsen vor, in der Funktionen, Parameter und Interaktion mit Linsen eingeordnet werden. Zusätzlich macht die Arbeit Vor- und Nachteile körpernaher Interaktion für Werkzeuge bzw. ihre Steuerung zum Thema und diskutiert dabei Nutzerposition und -bewegung an großen Displaywänden belegt durch empirische Nutzerstudien.
10

Content Distribution in Social Groups

Aggarwal, Saurabh January 2014 (has links) (PDF)
We study Social Groups consisting of self-interested inter-connected nodes looking for common content. We can observe Social Groups in various socio-technological networks, such as Cellular Network assisted Device-to-Device communications, Cloud assisted Peer-to-Peer Networks, hybrid Peer-to-Peer Content Distribution Networks and Direct Connect Networks. Each node wants to acquire a universe of segments at least cost. Nodes can either access an expensive link to the content distributor for downloading data segments, or use the well-connected low cost inter-node network for exchanging segments among themselves. Activation of an inter-node link requires cooperation among the participating nodes and reduces the cost of downloading for the nodes. However, due to uploading costs, Non-Reciprocating Nodes are reluctant to upload segments, in spite of their interest in downloading segments from others. We define the Give-and-Take (GT) criterion, which prohibits non-reciprocating behaviour in Social Groups for all nodes at all instants. In the “Full Exchange” case studied, two nodes can exchange copies of their entire segment sets, if each node gains at least one new segment from the other. Incorporating the GT criterion in the Social Group, we study the problem of downloading the universe at least cost, from the perspective of a new node having no data segments. We analyze this NP-hard problem, and propose algorithms for choosing the initial segments to be downloaded from the content distributor and the sequence of nodes for exchange. We compare the performance of these algorithms with a few existing P2P downloading strategies in terms of cost and running time. In the second problem, we attempt to reduce the load on the content distributor by choosing a schedule of inter-node link activations such that the number of nodes with the universe is maximized. Link activation decisions are taken by a central entity, the facilitator, for achieving the social optimum. We present the asymptotically optimal Randomized algorithm. We also present other algorithms, such as the Greedy Links algorithm and the Polygon algorithm, which are optimal under special scenarios of interest. We compare the performances of all proposed algorithms with the optimal value of the objective. We observe that computationally intensive algorithms exhibit better performance. Further, we consider the problem of decentralized scheduling of links. The decisions of link activations are made by the participating nodes in a distributed manner. While conforming to the GT criterion for inter-node exchanges, each node's objective is to maximize its utility. Each node tries to find a pairing partner by preferentially exploring nodes for link formation. Unpaired nodes choose to download a segment using the expensive link with Segment Aggressiveness Probability (SAP). We present linear complexity decentralized algorithms for nodes to choose their best strategy. We present a decentralized randomized algorithm that works in the absence of the facilitator and performs close to optimal for large number of nodes. We define the Price of Choice to benchmark performance of Social Groups (consisting of non-aggressive nodes) with the optimal. We evaluate the performance of various algorithms and characterize the behavioural regime that will yield best results for node and Social Group as well.

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