Dissertationen: „Co-Networks“

1

Morel, Victor. „Generating co-evolutionary polarized opinion networks“. Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-307147.

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In this thesis we present a co-evolutionary opinion network model, which aim to efficiently represent an online social network, with each person represented as a node attributed with an opinion, and the relations between people by edges. For this, we needed to classify the existing models through the prism of co-evolution, i.e. how the topology and the state of the network interact between each other, so one can find a model of classification for network models. This model will be compared under certain aspects to empirical data, as well as previous works. We show the emergence of a polarization of the opinions in the network, which appears only under certain conditions : a strong homophily between nodes, as well as a co-evolutionary behavior, i.e. a strong interaction between the topology and the state, of the model.

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2

Pires, David Laranjo. „Authorship attribution using co-occurrence networks“. Master's thesis, Universidade de Évora, 2021. http://hdl.handle.net/10174/30831.

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Atribuição de Autoria utlizando Redes de Co-Ocorrencia Nesta tese é abordada a tarefa de Atribuição de Autoria como uma tarefa de classificação. As metodologias utilizadas representam textos em grafos. Destes, várias medidas são extraídas, sendo utilizadas como amostras para o classificador. Já existem alguns trabalhos que também se focam nesta metodologia. Esta tese foca-se num método que divide o texto em várias partes e trata cada uma como um grafo. Deste, são extraídas as medidas, que são tratadas como uma série temporal, da qual são extraídos momentos. Assim, os momentos compõem o vetor final, representativo de todo o texto. A partir da metodologia aqui descrita surgem mais duas variações. A primeira variação omite o passo das séries temporais, e, por consequência, as várias medidas de cada grafo são utilizadas diretamente como amostras. A segunda variação representa todo o texto como um só grafo. As metodologias são testadas com corpus em Inglês e Português, com número variado de textos; Abstract: Authorship Attribution using Co-Occurrence Networks This thesis approaches the task of Authorship Attribution as a classification task. This is done using methodologies that represent text documents in graphs, from which several measures are extracted, to be used as samples for the classifier. There have been some works that also focus on this methodology. This thesis focuses on a methodology which splits the texts in multiple parts and treats each as a separate graph, from which measures are extracted. Each graph’s measures are treated as a time-series and moments are extracted. These moments make the final vector, representative of the entire text. This methodology is explored and extended with 2 variations. The first variation skips the time-series step, resulting in the various measures from each graph being used directly as samples. The second variation models the entire text as one graph. The methodologies are tested in corpus in both English and Portuguese, with varying number of texts.

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3

Xi, Wenna. „Community Structure in Co-Location Networks“. The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566156023255678.

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4

Kalluru, Vikram Gajanan. „Identify Condition Specific Gene Co-expression Networks“. The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338304258.

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5

Delgado, Román María del Carmen. „Organisation-based co-ordination of wireless sensor networks“. Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285080.

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Esta tesis presenta el Coalition Oriented Sensing Algorithm (COSA) como un mecanismo de auto-organización para redes de sensores inalámbricos (WSN). El objetivo del algoritmo es extender la vida útil de la red, al mismo tiempo que la funcionalidad básica de la misma – la monitorización fiel del entorno– también es garantizada. La evaluación del funcionamiento del algoritmo se apoya en una plataforma de simulación novedosa, RepastSNS. La implementación de COSA y la preparación de la plataforma para el desarrollo de los experimentos dan lugar a una estructura software reutilizable. Esta estructura favorece la implementación de futuras ampliaciones del algoritmo, así como su exportación a otros entornos. El uso de las WSNs se ha popularizado en los últimos años. Sus particulares características han favorecido la aplicación de las mismas a múltiples áreas. No obstante, la gestión energética de las WSNs sigue siendo objeto de estudio para los investigadores, que tratan de aliviar las fuertes restricciones que estas presentan en cuanto a disponibilidad de energía se refiere. En esta línea, se han propuesto diversas técnicas para conservación de la energía. La restricción energética es especialmente acusada cuando las WSNs se despliegan en entornos que no permiten la conexión de los nodos a la red ni la recarga de sus baterías. Este es el tipo de entorno considerado para la evaluación de COSA. El caso de uso estudiado considera una WSN desplegada a lo largo de un río navegable con el objetivo de monitorizar el estado del agua y detectar la presencia de polución en ella. La definición de COSA se inspira en el paradigma de los Sistemas Multiagente (MAS) mediante la identificación de los nodos de la WSN con agentes del MAS. COSA define un algoritmo para formación de coaliciones basado en diálogos por parejas de agentes (nodos). El algoritmo está completamente embebido en el comportamiento del agente. Los agentes que implementan COSA se comunican con sus vecinos para intercambiar información sobre su percepción del entorno y su estado. Como resultado de esta comunicación local, los agentes eligen su rol en la organización y establecen relaciones leader-follower. La definición de este tipo de relaciones se basa en dos funciones relacionales y un protocolo de negociación que establece las normas de coordinación. Los agentes se juntan en grupos para compensar la calidad de los datos recogidos y el consumo de energía asociado. Esta habilidad permite adaptar el consumo energético de la red a cambios en el entorno, al mismo tiempo que se satisfacen los objetivos de muestreo en cuanto a calidad de la información enviada al sink se refiere. Los resultados experimentales obtenidos apoyan las hipótesis preliminares en cuanto al comportamiento de COSA. A partir de estos resultados también se pone de manifiesto la relación existente entre la coordinación local y las ganancias obtenidas por el uso de COSA.
This thesis introduces the Coalition Oriented Sensing Algorithm (COSA) as a self-organisation mechanism for Wireless Sensor Networks (WSNs). This algorithm aims at extending the network lifetime at the same time that the primary goal of the network –faithfully monitoring the environment– is also guaranteed. The evaluation of the algorithm performance is based on a novel simulator, RepastSNS. The implementation of COSA and the development of its experimental setup define a reusable software structure to work over this simulation environment. It also favours the performance of future enhancements of the algorithm as well as its exportation. The use of WSNs has become widespread in the last years. The special characteristics of these networks have favoured their application to many different areas. One of the major concerns about WSNs refers to their energy management, as they are typically constraint in energy availability. This problem has gained the attention of researchers that try to improve this aspect of the WSNs by defining network energy conservation strategies. This constraint becomes especially acute when the network deployment environment does not allow for battery replenishment or node connection to the net. This is the case of the environment considered for COSA evaluation. The use case considered is a WSN deployed along a waterway in order to monitor the state of the water and detect the presence of pollutant sources. The definition of COSA is inspired by the Multiagent Systems (MAS) paradigm through the identification of nodes in a WSN with agents in a MAS. COSA defines a coalition formation algorithm based on peer-to-peer dialogues between neighbouring agents (nodes). The algorithm is completely embedded into the agent behaviour. Agents implementing COSA communicate with its neighbours to exchange information about their perception of the environment and their state. As a result of this local communication, agents select the role to play in the organisation and can then establish leader-follower relationships. The establishment of these peer-to-peer relationships is based on two relational functions and a negotiation protocol that lays down the norms of this co-ordination. Agents join in groups in order to trade off the accuracy of the sensed data and their energy consumption. As a consequence, COSA endows the network with self-organisation capacity. This ability is used to adapt energy consumption to changes in the environment and, at the same time, to fulfil sampling objectives in terms of the quality of the information reported to the sink. The results derived from experimentation support preliminary hypotheses about COSA good performance. They also provide insights on the relationship between local co-ordination and the gains obtained from COSA’s use.

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Hasan, Khondokar Fida. „GNSS time synchronisation in co-operative vehicular networks“. Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/120849/1/Khondokar%20Fida_Hasan_Thesis.pdf.

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This thesis is a comprehensive study of time synchronisation issues in vehicular communication networks. It reviews the requirements of time synchronization in cooperative vehicular networks and examines the feasibility of Global Navigation Satellite System (GNSS) timing techniques for synchronising the networks. Results from experiments show that GNSS time synchronisation methods can replace existing time synchronisation function (TSF) based synchronisation in vehicular networks by offering high precision and high accuracy.

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Mutwil, Marek. „Integrative transcriptomic approaches to analyzing plant co-expression networks“. Phd thesis, Universität Potsdam, 2011. http://opus.kobv.de/ubp/volltexte/2011/5075/.

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It is well documented that transcriptionally coordinated genes tend to be functionally related, and that such relationships may be conserved across different species, and even kingdoms. (Ihmels et al., 2004). Such relationships was initially utilized to reveal functional gene modules in yeast and mammals (Ihmels et al., 2004), and to explore orthologous gene functions between different species and kingdoms (Stuart et al., 2003; Bergmann et al., 2004). Model organisms, such as Arabidopsis, are readily used in basic research due to resource availability and relative speed of data acquisition. A major goal is to transfer the acquired knowledge from these model organisms to species that are of greater importance to our society. However, due to large gene families in plants, the identification of functional equivalents of well characterized Arabidopsis genes in other plants is a non-trivial task, which often returns erroneous or inconclusive results. In this thesis, concepts of utilizing co-expression networks to help infer (i) gene function, (ii) organization of biological processes and (iii) knowledge transfer between species are introduced. An often overlooked fact by bioinformaticians is that a bioinformatic method is as useful as its accessibility. Therefore, majority of the work presented in this thesis was directed on developing freely available, user-friendly web-tools accessible for any biologist.
Es ist bereits ausgiebig gezeigt worden, dass Gene, deren Expression auf Transkriptionsebene koordiniert ist, häufig auch funktional in verwandten Stoffwechselwegen vorkommen, und dass sich dies wahrscheinlich auch Spezies- und sogar Reichübergreifend sagen lässt (Ihmels et al., 2004). Anfänglich wurden solche Beziehungen verwendet, um sogenannte Genfunktionsmodule in Hefe und Säugern aufzudecken (Ihmels et al., 2004), um dann orthologe Genfunktionen zwischen verschiedene Spezies und Reichen zu entdecken (Stuart et al., 2003; Bergmann et al., 2004). Modellorganismen wie Arabidopsis werden bevorzugt in der Forschung verwendet, weil man durch die schnelle Generationszeit in kurzer Zeit viele Daten erheben kann und aufgrund dessen die Ressourcen- und Informationsvielfalt um ein Vielfaches größer ist. Ein Hauptziel ist der Wissenstransfer von Modellorganismen auf Spezies, die gesellschaftlich von höherer Bedeutung sind wie z.B. Getreidearten oder andere Feldfrüchte. Pflanzen besitzen oft große Genfamilien und die eindeutige Identifizierung von gut charakterisierten Arabidopsisorthologen in besagten Nutzpflanzen ist kein triviales Vorhaben. In der vorliegenden Arbeit werden Konzepte zur Nutzung von Co-expressionsnetzwerken beschrieben, die helfen sollen (i) Genfunktionen zu identifizieren, (ii) die Organisation von biologischen Prozessen aufzuklären und (iii) das erworbene Wissen auf andere Spezies übertragbar zu machen. Ein häufig von Bioinformatikern übersehender Umstand ist, dass bioinformatische Methoden nur so sinnvoll sind wie ihre Zugänglichkeit. Deshalb basiert der Großteil dieser Arbeit auf freiverfügbaren und vor allem für Biologen nutzerfreundlichen Webtools.

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Ziebell, Sara E. „A Powerful Correlation Method for Microbial Co-Occurrence Networks“. Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/595812.

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Motivation: Network interpretation using correlations has several known difficulties. Firstly, the data structure has discrete counts with an excess of zeros creating non-normal non-continuous data. Secondly, correlations, often used as similarity measures in network inference, are not causal. Thirdly, there is a masking effect of mutualism on commensalism and competition on amensalism in ecological networks that interfere with interpretation (Faust and Raes, 2012). More explicitly, the symmetric nature of correlations (cor(X,Y)=cor(Y,X)) can mask the affect of the asymmetric ecology relationship (commensalism and amensalism). We aim to solve the third issue which may speed up targeted drug therapies or disease diagnosis based on specific relationships in gut microbiomes. Methods: We apply a non-symmetric correlation method, Gini Correlations which should serve as a better classifier of ecological relationships revealing a fuller picture of microbiomes. First, create simulated correlated and independent Zero-Inflated Negative Binomial data. Second, validate Gini correlations by comparing Gini with Pearson Spearman and Kendall correlations; calculate false positive rate, true positive rate, accuracy, ROC, AUC after applying Benjamini-Hochberg (1995) multiple testing correction. Simulation Result: Gini is consistent and out performs other methods for small sample sizes of 10 and 25 producing consistently low false positive rates across 64+ simulation settings as well as consistently high accuracy rates. When sample size is increased to 50 Gini performs as well as other methods. Real Data Result: For well-defined microbial communities Gini correlations found novel biologically and medically relevant relationships. However, Gini's ability to unmask non-symmetric ecological relationships is yet to be determined.

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Roth, Camille. „Co-evolution in epistemic networks : reconstructing social complex systems“. Palaiseau, Ecole polytechnique, 2005. http://www.theses.fr/2005EPXX0057.

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Des agents produisant, manipulant et échangeant des connaissances constituent un système complexe socio-sémantique, dont l’étude représente un défi à la fois théorique, dans la perspective d’étendre la naturalisation des sciences sociales, et pratique, avec des applications permettant aux agents de connaître la dynamique du système dans lequel ils évoluent. Cette thèse se situe dans le cadre de ce programme de recherche. Parallèlement et plus largement, nous nous intéressons à la question de la reconstruction en sciences sociales. La reconstruction est un problème inverse comprenant deux volets complémentaires : (i) la déduction d’observations de haut-niveau à partir de phénomènes de bas-niveau ; et (ii) la reproduction de l’évolution des observations de haut-niveau à partir de la dynamique des objets de bas-niveau. Nous affirmons que plusieurs aspects significatifs de la structure d’une communauté de savoirs sont principalement produits par la dynamique d’un réseau épistémique où co-évoluent agents et concepts. En particulier, nous résolvons le premier volet du problème de la reconstruction en utilisant des treillis de Galois afin de recréer des taxonomies de communautés de savoirs à partir de simples relations entre agents et concepts; nous obtenons de fait une description historique se rapportant à la progression des champs, leur déclin, leur spécialisation ou leurs interactions (fusion ou scission). Nous micro-fondons ensuite la structure de ces communautés de savoirs en exhibant et en estimant empiriquement des processus d’interaction au niveau des agents, en co-évolution avec les concepts au sein du réseau épistémique, qui rendent compte de la morphogenèse et de l’émergence de plusieurs faits stylisés structurels de haut-niveau—il s’agit là du deuxième volet. Nous défendons finalement un point de vue épistémologique concernant la méthodologique générale de reconstruction d’un système complexe qui appuie notre choix d’un cadre coévolutionnaire
Agents producing and exchanging knowledge are forming as a whole a socio-semantic complex system. Studying such knowledge communities offers theoretical challenges, with the perspective of naturalizing further social sciences, as well as practical challenges, with potential applications enabling agents to know the dynamics of the system they are participating in. The present thesis lies within the framework of this research program. Alongside and more broadly, we address the question of reconstruction in social science. Reconstruction is a reverse problem consisting of two issues: (i) deduce a given high-level observation for a considered system from low-level phenomena; and (ii) reconstruct the evolution of high-level observations from the dynamics of lower-level objects. In this respect, we argue that several significant aspects of the structure of a knowledge community are primarily produced by the co-evolution between agents and concepts, i. E. The evolution of an epistemic network. In particular, we address the first reconstruction issue by using Galois lattices to rebuild taxonomies of knowledge communities from low-level observation of relationships between agents and concepts; achieving ultimately an historical description (inter alia field progress, decline, specialization, interaction - merging or splitting). We then micro-found various stylized facts regarding this particular structure, by exhibiting processes at the level of agents accounting for the emergence of epistemic community structure. After assessing the empirical interaction and growth processes, and assuming that agents and concepts are co-evolving, we successfully propose a morphogenesis model rebuilding relevant high-level stylized facts. We finally defend a general epistemological point related to the methodology of complex system reconstruction, eventually supporting our choice of a co-evolutionary framework

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Connor, Nora, Albert Barberán und Aaron Clauset. „Using null models to infer microbial co-occurrence networks“. PUBLIC LIBRARY SCIENCE, 2017. http://hdl.handle.net/10150/624498.

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Although microbial communities are ubiquitous in nature, relatively little is known about the structural and functional roles of their constituent organisms' underlying interactions. A common approach to study such questions begins with extracting a network of statistically significant pairwise co-occurrences from a matrix of observed operational taxonomic unit (OTU) abundances across sites. The structure of this network is assumed to encode information about ecological interactions and processes, resistance to perturbation, and the identity of keystone species. However, common methods for identifying these pairwise interactions can contaminate the network with spurious patterns that obscure true ecological signals. Here, we describe this problem in detail and develop a solution that incorporates null models to distinguish ecological signals from statistical noise. We apply these methods to the initial OTU abundance matrix and to the extracted network. We demonstrate this approach by applying it to a large soil microbiome data set and show that many previously reported patterns for these data are statistical artifacts. In contrast, we find the frequency of three-way interactions among microbial OTUs to be highly statistically significant. These results demonstrate the importance of using appropriate null models when studying observational microbiome data, and suggest that extracting and characterizing three-way interactions among OTUs is a promising direction for unraveling the structure and function of microbial ecosystems.

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11

Phlippen, Sandra. „Come close and co-create : proximities in pharmaceutical innovation networks /“. Rotterdam : Erasmus Universiteit, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=9789051709186.

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12

Lebo, Timothy M. „Guiding object recognition : a shape model with co-activation networks /“. Link to online version, 2005. http://hdl.handle.net/1850/993.

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13

Luoto, P. (Petri). „Co-primary multi-operator resource sharing for small cell networks“. Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526214979.

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Abstract The aim of this thesis is to devise novel co-primary spectrum sharing (CoPSS) methods for future fifth generation (5G) networks and beyond. The target is to improve data rates of small cell networks (SCNs) in which mobile network operators (MNOs) share their dedicated frequency spectrum (spectrum pooling) or a common spectrum (mutual renting). The performance of the proposed methods is assessed through extensive system-level simulations. MNOs typically acquire exclusive usage rights for certain frequency bands and have little incentive to share spectrums with other operators. However, due to higher cost and spectrum scarcity at lower frequencies it is expected that efficient use of the spectrum in 5G networks will rely more on spectrum sharing than exclusive licenses. This is especially true for new higher candidate frequencies (> 6 GHz) that do not have a pre-existing spectrum regulation framework. In the first part of the thesis, we tackle the challenge of providing higher data rates within limited spectral resources. Each SCN MNO has its own dedicated spectrum, and each MNO defines a percentage of how much its spectrum it is willing to share. The idea of the proposed CoPSS algorithms is that the spectrum is dynamically shared among MNOs based on their spectrum utilization, which is shared among MNOs in the network. This way interference can be avoided and spectrum utilization is maximized. Unused resources are shared equally between overloaded MNOs for a given time instant. Thus, only short-term fairness among overloaded SCNs can be guaranteed. In the second part, we consider a multi-operator small cell network where MNOs share a common pool of radio resources. The goal is to ensure the long term fairness of spectrum sharing without coordination among small cell base stations. We develop a decentralized control mechanism for base stations using the Gibbs sampling based learning tool, which allocates suitable amount of the spectrum for each base station while avoiding interference from SCNs and maximizing the total network throughput. In the studied scenarios, we show the importance of coordination among MNOs when the dedicated spectrum is shared. However, when MNOs share a common spectrum, a decentralized control mechanism can be used to allocate suitable amounts of spectrum for each base station. The proposed algorithms are shown to be effective for different network layouts, by achieving significant data rate enhancements with a low overhead
Tiivistelmä Tämä väitöskirja keskittyy kehittämään uusia menetelmiä, joilla jaetaan taajuuksia useiden operaattoreiden kesken tulevista viidennen sukupolven verkoista alkaen. Päätavoite on parantaa tiedonsiirtonopeuksia sellaisissa piensoluverkoissa, joissa matkapuhelinoperaattorit jakavat joko heidän omia taajuusalueitaan tai heillä yhteisomistuksessa olevia taajuuksia. Kehitettyjen menetelmien suorituskykyä arvioidaan mittavien järjestelmätason simulointien avulla. Matkapuhelinoperaattorit tyypillisesti omistavat yksin tietyt taajuusalueet, eivätkä ole valmiita jakamaan niitä. On kuitenkin oletettu, että tulevaisuudessa matkapuhelinoperaattorit joutuvat jakamaan taajuuksia, koska taajuusalueet ovat kalliita ja niukkoja erityisesti matalilla taajuusalueilla. Korkeammat taajuusalueet (> 6 GHz) puolestaan muodostavat otollisen alustan tehokkaalle spektrin jaetulle käytölle, koska niillä ei ole vielä olemassa olevaa taajuussääntelyä. Väitöskirjan ensimmäisessä osassa keskitytään kasvattamaan tiedonsiirtonopeuksia kun jokainen matkapuhelinoperaattori omistaa oman taajuuskaistansa ja matkapuhelinoperaattorit määrittävät kuinka suuren prosentuaalisen osuuden ovat valmiita jakamaan. Esitettyjen algoritmien päätavoite on jakaa taajuuksia dynaamisesti matkapuhelinoperaattoreiden kesken. Algoritmeissa hyödynnetään tietoa matkapuhelinoperaattoreiden taajuuden käyttöasteesta, jonka matkapuhelinoperaattoritkommunikoivat toisilleen. Näin häiriö voidaan välttää ja taajuuden käyttö maksimoidaan. Käyttämättömät taajuudet jaetaan tasaisesti matkapuhelinoperaattorien kesken tietyllä ajanhetkellä. Näin voidaan taata lyhytaikainen oikeudenmukainen taajuuksien käyttö, mutta ei pitkäaikaista oikeudenmukaista taajuuksien käyttöä. Väitöskirjan toisessa osassa matkapuhelinoperaattorit jakavat yhteisomistuksessa olevia taajuuksia. Tavoitteena on saavuttaa pitkäaikainen taajuuksien oikeudenmukainen käyttö, kun piensoluverkot eivät kommunikoi keskenään. Työssä kehitetään piensoluverkoille hajautettu algoritmi, joka perustuu oppimistyökaluun Gibbs-näytteistys. Näin saadaan allokoitua jokaiselle tukiasemalle tarvittava määrä taajuusresursseja niin, että häiriö tukiasemien välillä minimoidaan ja koko piensoluverkon suorituskyky maksimoidaan. Tutkituissa skenaarioissa osoitetaan matkapuhelinoperaattoreiden välisen koordinaation tärkeys, kun jaetaan omia taajuusalueita. Toisaalta kun operaattorit jakavat yhteisomistuksessa olevia taajuuksia on mahdollista käyttää algoritmeja, joissa ei ole koordinaatiota matkapuhelinoperaattoreiden kesken. Väitöskirjassa vahvistetaan kehitettyjen algoritmien olevan tehokkaita ja sopivan monenlaisiin verkkoympäristöihin saavuttaen merkittäviä parannuksia tiedonsiirtonopeuteen ilman suuria kustannuksia

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Song, Haoran. „MMSP : an alternative transport protocol for multiple co-existing networks“. Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/5417.

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Mobile Multi-Streaming Protocol (MMSP) is a new protocol combining and abstracting the essential functionalities of TCP and UDP for multiple coex isting networks. It inherits the good characteristics from TCP while over comes many drawbacks from it. The most important features of MMSP is multi-streaming within a single connection. Our work proposes, investigates and provides a concept for maintaining a reliable connection by setting up multiple streams via different network interfaces. We designed and imple mented a bunch of new packet formats, algorithms and state machines. Our experiments have successfully proved that MMSP provides a func tional solution to satisfy many requirements for up-layer protocols and ap plications in both wired and wireless networks, producing higher network throughput, security and reliability. Especially for mobile networks, the unique design and characteristics of MMSP is in the ascendant. It is a successful protocol extension of the transport layer on IP stack.

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Rupp, Thomas Manfred. „Supply information provision for co-operation in complex production networks“. Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270502.

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16

Khare, Vineet R. „Automatic problem decomposition using co-evolution and modular neural networks“. Thesis, University of Birmingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435412.

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17

Zhang, Jingyao. „Hardware-Software Co-Design for Sensor Nodes in Wireless Networks“. Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/50972.

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Simulators are important tools for analyzing and evaluating different design options for wireless sensor networks (sensornets) and hence, have been intensively studied in the past decades. However, existing simulators only support evaluations of protocols and software aspects of sensornet design. They cannot accurately capture the significant impacts of various hardware designs on sensornet performance. As a result, the performance/energy benefits of customized hardware designs are difficult to be evaluated in sensornet research. To fill in this technical void, in first section, we describe the design and implementation of SUNSHINE, a scalable hardware-software emulator for sensornet applications.
SUNSHINE is the first sensornet simulator that effectively supports joint evaluation and design of sensor hardware and software performance in a networked context. SUNSHINE captures the performance of network protocols, software and hardware up to cycle-level accuracy through its seamless integration of three existing sensornet simulators: a network simulator TOSSIM, an instruction-set simulator SimulAVR and a hardware simulator
GEZEL. SUNSHINE solves several sensornet simulation challenges, including data exchanges and time synchronization across different simulation domains and simulation accuracy levels. SUNSHINE also provides hardware specification scheme for simulating flexible and customized hardware designs. Several experiments are given to illustrate SUNSHINE\'s simulation capability. Evaluation results are provided to demonstrate that SUNSHINE is an efficient tool for software-hardware co-design in sensornet research.

Even though SUNSHINE can simulate flexible sensor nodes (nodes contain FPGA chips as coprocessors) in wireless networks, it does not estimate power/energy consumption of sensor nodes. So far, no simulators have been developed to evaluate the performance of such flexible nodes in wireless networks. In second section, we present PowerSUNSHINE, a power- and energy-estimation tool that fills the void. PowerSUNSHINE is the first scalable power/energy estimation tool for WSNs that provides an accurate prediction for both fixed and flexible sensor nodes. In the section, we first describe requirements and challenges of building PowerSUNSHINE. Then, we present power/energy models for both fixed and flexible sensor nodes. Two testbeds, a MicaZ platform and a flexible node consisting of a microcontroller, a radio and a FPGA based co-processor, are provided to demonstrate the simulation fidelity of PowerSUNSHINE. We also discuss several evaluation results based on simulation and testbeds to show that PowerSUNSHINE is a scalable simulation tool that provides accurate estimation of power/energy consumption for both fixed and flexible sensor nodes.

Since the main components of sensor nodes include a microcontroller and a wireless transceiver (radio), their real-time performance may be a bottleneck when executing computation-intensive tasks in sensor networks. A coprocessor can alleviate the burden of microcontroller from multiple tasks and hence decrease the probability of dropping packets from wireless channel. Even though adding a coprocessor would gain benefits for sensor networks, designing applications for sensor nodes with coprocessors from scratch is challenging due to the consideration of design details in multiple domains, including software, hardware, and network. To solve this problem, we propose a hardware-software co-design framework for network applications that contain multiprocessor sensor nodes. The framework includes a three-layered architecture for multiprocessor sensor nodes and application interfaces under the framework. The layered architecture is to make the design of multiprocessor nodes\' applications flexible and efficient. The application interfaces under the framework are implemented for deploying reliable applications of multiprocessor sensor nodes. Resource sharing technique is provided to make processor, coprocessor and radio work coordinately via communication bus. Several testbeds containing multiprocessor sensor nodes are deployed to evaluate the effectiveness of our framework. Network experiments are executed in SUNSHINE emulator to demonstrate the benefits of using multiprocessor sensor nodes in many network scenarios.
Ph. D.

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18

Philippen, Sandra Magdalena Wilhelmina. „Come close and co-create proximities in pharmaceutical innovation networks /“. [Amsterdam] : Rotterdam : Thela Thesis ; Erasmus University [Host], 2008. http://hdl.handle.net/1765/13754.

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19

Ali, Mohamad Jaafar. „Wireless body area networks : co-channel interference mitigation & avoidance“. Thesis, Sorbonne Paris Cité, 2017. http://www.theses.fr/2017USPCB252/document.

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L’amélioration de la qualité et de l’efficacité en santé est un réel enjeu sociétal. Elle implique la surveillance continue des paramètres vitaux ou de l’état mental du sujet. Les champs d’applications sont vastes : l’application la plus importante est la surveillance des patients à distance. Les avancées en micro-électronique, capteurs et réseaux sans-fil permettent aujourd’hui le développement de systèmes ambulatoires performants pour le monitoring de paramètres physiologiques, capables de prendre en compte d’importantes contraintes techniques : forte intégration pour la réduction de la taille et faible consommation pour une plus grande autonomie [1]. Cependant, la conception de ce type de réseaux de capteurs médicaux WBANs (Wireles Body Area Networks) se heurte à un certain nombre de difficultés techniques, provenant des contraintes imposées par les capacités réduites des capteurs individuels : basse puissance, énergie limitée et faible capacité de stockage. Ces difficultés requièrent des solutions différentes, encore très embryonnaires, selon l’application visée (monitoring à but médical). La forte mobilité et le changement rapide de la topologie du réseau dévoilent un verrou scientifique et social. En outre, l’interférence de différents capteurs constituant le WBAN augmente la difficulté de la mise en place de ce type de réseaux. De nombreuses solutions dans la littérature ont été étudiées, comme nous allons illustrer dans ce manuscrit, néanmoins elles restent limitées. Nous nous intéresserons tout particulièrement à la gestion des interférences Intra- et Inter-WBAN, leur impacte sur la fiabilité des transmissions (des liens) et la durée de vie de ce type de réseaux. Plus précisément, nous abordons ces problématiques en se basant sur des modélisations théoriques et analytiques et avec une conception pratique des solutions proposées. Afin d’atteindre les objectifs cités ci-dessous, nous abordons quatre solutions : • Une gestion des interférences intra-WBAN • Une gestion coopérative des interférences Inter-WBAN • Une gestion non coopérative des interférences, Inter-WBAN • Une gestion des interférences WBAN dans un contexte IoT Dans la première partie de cette thèse et afin de répondre en partie aux problèmes de gestion des interférences Intra-WBAN. Nous présentons deux mécanismes pour le WBAN : (a) CFTIM qui alloue dynamiquement des slots et des canaux dit- stables (avec un taux d’interférences le bas possible dans le temps) pour réduire les interférences intra-WBAN. (b) IAA ajuste dynamiquement la taille du superframe et limite le nombre de canaux à 2 pour abaisser les interférences Intra-WBAN et ainsi économiser l’énergie. Une validation avec un model probabiliste est proposé afin de valider théoriquement l’efficacité de notre solution. Les résultats de la simulation démontrent l’efficacité du CFTIM et de l’IAA en termes de réduction de la probabilité d’interférence, l’extension de la durée de vie du réseau et l’amélioration du débit et de la fiabilité des transmissions. Notre seconde contribution, propose une gestion coopératives des interférences Inter-WBAN en utilisant des codes orthogonaux. Motivé par un approvisionnement temporel distribué basé sur la norme [2] IEEE 802.15.6, nous proposons deux solutions. (a) DTRC qui fournit à chaque WBAN les connaissances sur les superframes qui se chevauchent. Le second, (b) OCAIM qui attribue des codes orthogonaux aux capteurs appartenant à deux listes de groupe de capteur en interférences de deux WBAN différents (SIL). Les résultats démontrent qu’OCAIM diminue les interférences, améliore le débit et préserve la ressources énergétiques. La troisième partie nous a permis d’aborder la gestion des interférences, mais cette fois ci d’une manière non-coopérative en se basant sur l’affectation couple Slot/Canal. Plus précisément, nous proposons deux schémas basés sur les carrés latins. (...)
A Wireless Body Area Network (WBAN) is a short-range network that consists of a coordinator (Crd) and a collection of low-power sensors that can be implanted in or attached to the human body. Basically, WBANs can provide real-time patient monitoring and serve in various applications such as ubiquitous health-care, consumer electronics, military, sports, etc. [1]. As the license-free 2.4 GHz ISM band is widely used among WBANs and across other wireless technologies, the fundamental problem is to mitigate the resulting co-channel interference. Other serious problems are to extend the network lifetime and to ensure reliable transmission within WBANs, which is an urgent requirement for health-care applications. Therefore, in this thesis, we conduct a systematic research on a few number of research problems related to radio co-channel interference, energy consumption, and network reliability. Specifically, we address the following problems ranging from theoretical modeling and analysis to practical protocol design: • Intra-WBAN interference mitigation and avoidance • Cooperative inter-WBAN interference mitigation and avoidance • Non-cooperative inter-WBAN interference mitigation and avoidance • Interference mitigation and avoidance in WBANs with IoT Firstly, to mitigate the intra-WBAN interference, we present two mechanisms for a WBAN. The first is called CSMA to Flexible TDMA combination for Interference Mitigation, namely, CFTIM, which dynamically allocates time-slots and stable channels to lower the intra-WBAN interference. The second is called Interference Avoidance Algorithm, namely IAA that dynamically adjusts the superframe length and limits the number of channels to 2 to lower the intra-WBAN interference and save energy. Theoretically, we derive a probabilistic model that proves the SINR outage probability is lowered. Simulation results demonstrate the effectiveness and the efficiency of CFTIM and IAA in terms of lowering the probability of interference, extending network lifetime, improving throughput and reliability. Secondly, we address the problem of interference among cooperative WBANs through using orthogonal codes. Motivated by distributed time provisioning supported in IEEE 802.15.6 standard [2], we propose two schemes. The first is called Distributed Time Correlation Reference, namely, DTRC that provides each WBAN with the knowledge about which superframes overlap with each other. The second is called Orthogonal Code Allocation Algorithm for Interference Mitigation, namely, OCAIM, that allocates orthogonal codes to interfering sensors belonging to sensor interference lists (SILs), which are generated based on the exchange of power-based information among WBANs. Mathematically, we derive the successful and collision probabilities of frames transmissions. Extensive simulations are conducted and the results demonstrate that OCAIM can diminish the interference, improve the throughput and save the power resource. Thirdly, we address the problem of co-channel interference among non-cooperative WBANs through time-slot and channel hopping. Specifically, we propose two schemes that are based on Latin rectangles. The first is called Distributed Algorithm for Interference mitigation using Latin rectangles, namely, DAIL that allocates a single channel to a timeslot combination to each sensor to diminish inter-WBAN interference and to yield better schedules of the medium access within each WBAN. The second is called Channel Hopping for Interference Mitigation, namely, CHIM, which generates a predictable interference free transmission schedule for all sensors within a WBAN. CHIM applies the channel switching only when a sensor experiences interference to save the power resource. Furthermore, we present an analytical model that derives bounds on collision probability and throughput for sensors transmissions. (...)

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20

MORICI, ANDREA. „HW/SW Co-Design of low-power wireless sensor networks“. Doctoral thesis, Università Politecnica delle Marche, 2009. http://hdl.handle.net/11566/242271.

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21

Yasmeen, Gisèle. „Mutual aid networks in two feminist housing co-operatives in Montreal“. Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60577.

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This thesis deals with the social relations within two feminist-inspired housing co-operatives in Montreal by employing the analytical tool of social network from an interactionist perspective. The housing co-op milieu is a highly suitable terrain for reflections on feminist urban theory. 'Public' and 'private' space, identity and place, and 'community' and community development are central themes addressed in this study.
Members of each co-op were interviewed using a semi-directed interview guide. Social interaction is analysed qualitatively and focuses on the content of exchanges between co-op residents and patterns of socialising. The study concludes with an analysis of spatial micropolitics in terms of conflict and co-operation.

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22

Petigara, Noshirwan Kavas 1979. „CRAM : co-operative routing and memory for networks of embedded sensors“. Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/87284.

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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.
Includes bibliographical references (leaves 66-69).
by Noshirwan Kavas Petigara.
M.Eng.

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23

Marshall, Paul. „Inventing television : transnational networks of co-operation and rivalry, 1870-1936“. Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/inventing-television-transnational-networks-ofcooperation-and-rivalry-18701936(3b368b90-9755-4511-9b77-7edc9644f91f).html.

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In this thesis, I seek to understand what shaped the development of television, tracing the technology back to its earliest roots. In existing literature, the history of television in its formative years (before World War II), has largely been presented in technologically deterministic terms, culminating in the ‘goal’ of adding ‘sight to sound’ – producing a wireless set with pictures. Most of the existing literature focuses on ‘hero’ figures such as British inventor John Logie Baird and his electro-mechanical television systems, or on corporate narratives such as that of RCA in the United States in developing all-electronic television. In contrast to such an approach, I will concentrate on the transnational networks linking individuals and companies, and on the common external factors affecting all of them. Some networks could operate simultaneously as rivals and collaborators, as was the case with companies such as Marconi-EMI in Britain and RCA in the United States. Senior managers and researchers such as Isaac Shoenberg at Marconi-EMI and Vladimir Zworykin at RCA played significant roles, but so too did relatively obscure figures such as Russian scientist Boris Rosing and British engineer Alan A Campbell Swinton. I will draw on newly available sources from Russia and the USSR, on over-looked sources in Britain and the United States, and on replicative technology to re-examine the story. The new material, coupled with the transnational networks approach, enables fresh insights to be gained on issues of simultaneity of invention and on contingency in the development and initial deployments of the technology. By using these fresh primary sources, and by re-interpreting some aspects of the numerous existing secondary sources, I will show that the ‘wireless with pictures’ model was not inevitable, that electro-mechanical television need not have been a technical cul-de-sac, and that in Britain at least, it was the political desire to maintain and extend the monopoly of the BBC, which effectively funnelled the technology into the model so familiar to us today.

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24

George, Karina Anne. „Synthesis, characterisation and invitro evaluation of PLLA-co-succinic anhydride networks“. Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16494/1/Karina_Anne_George_Thesis.pdf.

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The biocompatibility and the in vivo degradation of poly(L-lactide), (PLLA)- based materials has prompted much interest in the development of these materials into scaffolds for tissue engineering applications. PLLA-based polymers have been available for use in craniomaxillofacial surgery since 1991. Usually, a plate or sheet of the polymer is placed in or over a defect in the bone. Ideally the bone will use the polymer as a support to repair the defect and as the polymer degrades, the bone will continually remodel, so that the loss of mass and mechanical strength of the polymer correlates with the increase in the mass and strength of the new bone. However, this is an ideal situation, and is not always observed in practice. The aim of this work is to develop PLLA-based materials that should encourage bone growth onto the material and allow control over the rate of degradation. PLLA-co-succinic anhydride networks were synthesised and the mineralisation and degradation of these materials were evaluated in vitro. The synthesis of these networks, involved the polymerisation of 4-arm star PLLA polymers, which were coupled through their end groups with succinic anhydride. The low molecular weight star PLLA polymers were synthesised using calcium hydride and pentaerythritol as initiator and co-initiator respectively. Calcium hydride was preferred to stannous octoate in this study as there is concern over the release of tin-containing when the polymer is implanted. As only very limited studies have been directed into the polymerisation and resulting polymers formed using calcium hydride, this was a major focus of the study. The identification of hydrogen in the reaction tubes was evidence that calcium alkoxide, formed from the reaction of pentaerythritol and calcium hydride, is the actual initiating species for the ring opening polymerisation. In situ FT-Raman spectroscopy was used as a tool to monitor the reaction process and was found to be a convenient and reliable method for obtaining information about the polymerisation kinetics. Analysis of the FTRaman kinetic curves, along with analysis of products by GPC, polarimetry and NMR spectroscopy showed that the polymerisation was 'quasi-living' depending on the ratio of pentaerythritol and calcium hydride in the system. Furthermore, both the degree of transesterification and racemisation of polymers synthesised in optimised reactions were low. The PLLA-co-succinic anhydride networks were synthesised by coupling of hydroxyl-terminated PLLA star polymers with succinic anhydride (one-pot reaction) and by coupling hydroxyl-terminated PLLA stars with succinic anhydride-terminated PLLA star polymers (two-pot reaction), using a carbodiimide, EDC to mediate the esterification. The one-pot reaction produced polymers with high gel fractions and high conversion of functional groups in the gel, whereas the gel fraction and conversion of functional groups was lower in the two-pot reaction. For the networks synthesised in the one-pot reaction, the molecular weight between crosslinks was controlled by the length of the PLLA polymer arms. The networks synthesised were characterised by FTIR-ATR spectroscopy, SEM, contact angle and by swelling. The extent of mineralisation of the PLLA-co-succinic anhydride networks in simulated body fluid (SBF) after 14 days was greater than the mineral deposition on the high molecular weight PLLA reference polymer. The degradation of the networks was carried out under accelerated conditions in 0.1 M NaOH at 37 degrees Celsius. All networks degraded much more slowly than the high molecular weight linear PLLA reference sample. The rate of degradation was found to be dependent on the crystallinity of the polymer chains, with the more crystalline networks degrading at a faster rate, while the location of the degradation, surface or bulk, was controlled by the crosslink density, showing that the degradation is 'tuneable'.

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25

George, Karina Anne. „Synthesis, characterisation and invitro evaluation of PLLA-co-succinic anhydride networks“. Queensland University of Technology, 2006. http://eprints.qut.edu.au/16494/.

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The biocompatibility and the in vivo degradation of poly(L-lactide), (PLLA)- based materials has prompted much interest in the development of these materials into scaffolds for tissue engineering applications. PLLA-based polymers have been available for use in craniomaxillofacial surgery since 1991. Usually, a plate or sheet of the polymer is placed in or over a defect in the bone. Ideally the bone will use the polymer as a support to repair the defect and as the polymer degrades, the bone will continually remodel, so that the loss of mass and mechanical strength of the polymer correlates with the increase in the mass and strength of the new bone. However, this is an ideal situation, and is not always observed in practice. The aim of this work is to develop PLLA-based materials that should encourage bone growth onto the material and allow control over the rate of degradation. PLLA-co-succinic anhydride networks were synthesised and the mineralisation and degradation of these materials were evaluated in vitro. The synthesis of these networks, involved the polymerisation of 4-arm star PLLA polymers, which were coupled through their end groups with succinic anhydride. The low molecular weight star PLLA polymers were synthesised using calcium hydride and pentaerythritol as initiator and co-initiator respectively. Calcium hydride was preferred to stannous octoate in this study as there is concern over the release of tin-containing when the polymer is implanted. As only very limited studies have been directed into the polymerisation and resulting polymers formed using calcium hydride, this was a major focus of the study. The identification of hydrogen in the reaction tubes was evidence that calcium alkoxide, formed from the reaction of pentaerythritol and calcium hydride, is the actual initiating species for the ring opening polymerisation. In situ FT-Raman spectroscopy was used as a tool to monitor the reaction process and was found to be a convenient and reliable method for obtaining information about the polymerisation kinetics. Analysis of the FTRaman kinetic curves, along with analysis of products by GPC, polarimetry and NMR spectroscopy showed that the polymerisation was 'quasi-living' depending on the ratio of pentaerythritol and calcium hydride in the system. Furthermore, both the degree of transesterification and racemisation of polymers synthesised in optimised reactions were low. The PLLA-co-succinic anhydride networks were synthesised by coupling of hydroxyl-terminated PLLA star polymers with succinic anhydride (one-pot reaction) and by coupling hydroxyl-terminated PLLA stars with succinic anhydride-terminated PLLA star polymers (two-pot reaction), using a carbodiimide, EDC to mediate the esterification. The one-pot reaction produced polymers with high gel fractions and high conversion of functional groups in the gel, whereas the gel fraction and conversion of functional groups was lower in the two-pot reaction. For the networks synthesised in the one-pot reaction, the molecular weight between crosslinks was controlled by the length of the PLLA polymer arms. The networks synthesised were characterised by FTIR-ATR spectroscopy, SEM, contact angle and by swelling. The extent of mineralisation of the PLLA-co-succinic anhydride networks in simulated body fluid (SBF) after 14 days was greater than the mineral deposition on the high molecular weight PLLA reference polymer. The degradation of the networks was carried out under accelerated conditions in 0.1 M NaOH at 37 degrees Celsius. All networks degraded much more slowly than the high molecular weight linear PLLA reference sample. The rate of degradation was found to be dependent on the crystallinity of the polymer chains, with the more crystalline networks degrading at a faster rate, while the location of the degradation, surface or bulk, was controlled by the crosslink density, showing that the degradation is 'tuneable'.

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26

Norling, Kristoffer. „A Performance Evaluation of Secure Distributed Co-Simulation over Wide Area Networks“. Thesis, Linköping University, Department of Computer and Information Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15786.

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Different types of models often require different tools and environments to be modeled and simulated. These tools and environments are specialized to handle specific purposes. The models created for these special purposes can then be included in the modeling and simulation of large complex systems. This scenario increases the motivation to use a co-simulation technique. Co-simulation allows for coupling of different simulators into one coherent simulation. Different parts of a system are often modeled by different departments within an enterprise or by subcontractors. Since the models often are describing enterprises’ primary know-how they become important business assets. This raises the need for a secure modeling and simulation approach. This thesis discusses different approaches regarding how to securely simulate and distribute models. We focus on a distributed co-simulation approach over wide area networks (WANs), using transmission line modeling (TLM). The approach is tested in an experimental environment at Linköping University, Sweden, and by real condition co-simulations between Sweden and Australia. A series of experiments are conducted using a simulated WAN environment and the results are put in relation to the real encrypted simulations between Sweden and Australia. We measure the performance during the simulations and evaluate the results. We observe that by distributing the co-simulation we suffer from performance losses. These losses and what parameters cause them is our primary emphasis in the evaluation. We also see that there are two types of parameters that affect the total simulation time in the distributed environment. First there are parameters that belong to the models, and then there are parameters that belong to the WAN environment. We conclude that several of the parameters have effect on the total simulation time. Especially the network delay (latency) has a significant impact.

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27

Azimi, Reza. „Co-operative Driving at Intersections using Vehicular Networks and Vehicle-Resident Sensing“. Research Showcase @ CMU, 2015. http://repository.cmu.edu/dissertations/584.

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Road intersections are considered to be serious bottlenecks of urban transportation. According to the U.S., European, and global statistics, intersection-related crashes, with fatal outcome, represent approximately 20 percent of all traffic fatalities. More than 44% of all reported crashes in the U.S. occur within intersection areas, which, in turn, lead to 8,500 fatalities and approximately 1 million injuries every year [1]. Furthermore, the impact of road intersections on traffic delays leads to enormous waste of human and natural resources. Statistics collected by FHWA in 2011 urban mobility report states that the average intersection delay endured by a commuter is 34 hours every year. The cost of this wasted time and related fuel consumption at intersection congestions is over $101 billion a year [2]. Therefore, it is critical to address these safety and throughput concerns as one of the main challenges for manual as well as autonomous driving through intersections. This dissertation studies the problem of managing traffic through intersections, and develops new decentralized, reliable and efficient active safety methods to provide safe and efficient passage through intersections and roundabouts. Our cyber-physical framework called STIP (Spatio-Temporal Intersection Protocols) incorporates a fusion of vehicle-to-vehicle (V2V) communications, vehicle-to-infrastructure (V2I) communications and vehicle-resident sensing to enable co-operative driving of autonomous and manually-driven vehicles at intersections. The proposed system allows vehicles to traverse safely by avoiding vehicle collisions at intersections, and significantly increase traffic throughput. The STIP framework includes a family of distributed protocols and covers the following two main traffic environments, categorized based on the market penetration of autonomous vehicles: (1) Homogeneous Traffic: autonomous vehicles only, (2) Heterogeneous Traffic: mix of human-driven and autonomous vehicles. For the homogeneous traffic category, we introduce two sets of intersection protocols: (1) V2V-Intersection Protocols, which rely on V2V communications and localization to avoid vehicle collisions at intersections by controlling and navigating them within the intersection area. Autonomous vehicles approaching an intersection use DSRC to periodically broadcast information such as position, heading and intersection crossing intentions to other vehicles. The vehicles then decide among themselves regarding who crosses first, who goes next and who waits. (2) Synchronized movement-intersection protocols, which are designed to increase the parallelism at intersections by allowing the concurrent crossing of vehicles arriving from all directions. This method enforces synchronized and staggered arrival of vehicles at intersections. This method allows vehicles to cross the intersection without stopping or slowing down, and maximizes the capacity utilization of the intersection space. In case of the heterogeneous traffic category, in order to enable the safe co-existence of manually-driven and autonomous vehicles at intersections, we propose a set of communication-based and perception-based protocols, leveraging a fusion of V2V, V2I and on-board sensor systems such as cameras, radars and lidars. In this dissertation, we formally prove the deadlock-freedom property of our family of intersection protocols, and study the effects of packet loss on our V2V intersection protocols and measure the reliability of these protocols in the presence of channel impairments. We also measure the impact of position inaccuracy of commonly-used GPS devices on our V2V-intersection protocols and incorporate required modifications to guarantee their safety and efficiency despite these impairments. Additionally, we study sensor inaccuracy and occlusion’s impact on our perception-based intersection protocols, and propose simple solutions to deal with these shortcomings. The functionality of our methods is evaluated using our vehicular networks emulator-simulator, called AutoSim. Our results indicate that our proposed STIPs provide both safe passage through the intersection and significantly decrease the delay at the intersection by increasing the concurrency. Specifically, one of our V2V-intersection protocols yields over 87% overall performance improvement over the common traffic light signalized intersections. Throughput increases are even more significant in the case of our synchronized movement intersection protocols, as intersection delays are reduced up to 96% compared to the common traffic light signalized intersections, and the optimal intersection capacity utilization of 100% is achieved in certain cases.

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Marcos, Carla Abregú, Abraham Sopla Maslucán, Miguel Cano Lengua und José C. Alvarez. „Co-authors Networks in Adsorption Refrigeration and Air-Conditioning with Solar Energy“. Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/653778.

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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.
The refrigeration and air conditioning systems by adsorption with solar energy are a very interesting option to replace the conventional compression systems because they save energy, are noiseless and use non-aggressive ozone layer refrigerants; however, there are scarcities of studies at this topic. The acquisition of knowledge and positioning in research on this topic by new research groups could be facilitated by knowing the context, trends, and collaborations that emerge in the subject. A map of collaborative co-authors between the greatest authors on the subject was drawn up, the same one that is done using Gephi software. From the analysis of these maps, the centrality degree and collaboration between the authors were determined.
Revisión por pares

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29

Manepalli, Sarika. „Enhanced handoff algorithm for the co-existence of mobile IPV4 and IPV6 networks“. Thesis, Wichita State University, 2009. http://hdl.handle.net/10057/2423.

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As wireless technology has improved, the demand for constant internet connectivity increased. With the invention of Mobile IP, users are still more interested to have connection to the internet while moving from one network to another. During the mobility, the mobile host moves from one network to another, undergoes the handoff process, and registers with the new network. Due to the scarcity of IPv4 addresses and other limitations, new Internet Protocol version 6 (IPv6) has evolved. In the real world, planning is being done to deploy IPv6 along with the IPv4 network. The IPv6 node should understand IPv4 addressing and its features while communicating with it. When considering mobility in both IPv4 and IPv6 networks together, it is a bit complicated where either the mobile host or any other entity in the network should understand both IPv4 and IPv6 networks. In this thesis, research was centralized in the scenario where both internet protocol versions IPv4 and IPv6 are active and mobility is introduced between them. The research deals with the handoff process and registration of the mobile node with the agent in the new network. The author proposed a new handoff algorithm with the basic security involved in the process which can be used as model before planning to introduce mobility between IPv4 and IPv6 protocols. The significance of the algorithm is to reduce the handoff latency by enhancing the functionality of the Tunnel End Point (TEP); this in turn reduces the tunneling of the data twice. The research, analysis is done on the complete handoff process by varying different parameters involved in the process. An analytical model is proposed to support the algorithm. The effects of the parameters are studied. The results of the proposed analytical model were studied in comparison with the traditional schemes.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical and Computer Engineering

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30

Karamanos, Anastasios. „Co-operative networks and the value of the firm : a structural embeddedness perspective“. Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289613.

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31

Chen, Kan. „Physical layer security in co-operative MIMO networks - key generation and reliability evaluation“. Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32839.

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Doctor of Philosophy
Department of Electrical and Computer Engineering
Balasubramaniam Natarajan
Widely recognized security vulnerabilities in current wireless radio access technologies undermine the benefits of ubiquitous mobile connectivity. Security strategies typically rely on bit-level cryptographic techniques and associated protocols at various levels of the data processing stack. These solutions have drawbacks that have slowed down the progress of new wireless services. Physical layer security approaches derived from an information theoretic framework have been recently proposed with secret key generation being the primary focus of this dissertation. Previous studies of physical layer secret key generation (PHY-SKG) indicate that a low secret key generation rate (SKGR) is the primary limitation of this approach. To overcome this drawback, we propose novel SKG schemes to increase the SKGR as well as improve the security strength of generated secret keys by exploiting multiple input and multiple output (MIMO), cooperative MIMO (co-op MIMO) networks. Both theoretical and numerical results indicate that relay-based co-op MIMO schemes, traditionally used to enhance LTE-A network throughput and coverage, can also increase SKGR. Based on the proposed SKG schemes, we introduce innovative power allocation strategies to further enhance SKGR. Results indicate that the proposed power allocation scheme can offer 15% to 30% increase in SKGR relative to MIMO/co-op MIMO networks with equal power allocation at low-power region, thereby improving network security. Although co-op MIMO architecture can offer significant improvements in both performance and security, the concept of joint transmission and reception with relay nodes introduce new vulnerabilities. For example, even if the transmitted information is secured, it is difficult but essential to monitor the behavior of relay nodes. Selfish or malicious intentions of relay nodes may manifest as non-cooperation. Therefore, we propose relay node reliability evaluation schemes to measure and monitor the misbehavior of relay nodes. Using a power-sensing based reliability evaluation scheme, we attempt to detect selfish nodes thereby measuring the level of non-cooperation. An overall node reliability evaluation, which can be used as a guide for mobile users interested in collaboration with relay nodes, is performed at the basestation. For malicious behavior, we propose a network tomography technique to arrive at node reliability metrics. We estimate the delay distribution of each internal link within a co-op MIMO framework and use this estimate as an indicator of reliability. The effectiveness of the proposed node reliability evaluations are demonstrated via both theoretical analysis and simulations results. The proposed PHY-SKG strategies used in conjunction with node reliability evaluation schemes represent a novel cross-layer approach to enhance security of cooperative networks.

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SABATINI, ANDREA. „Analysing new Product Development and Co-creation in Industrial Networks: Pathways and Capabilities“. Doctoral thesis, Università Politecnica delle Marche, 2019. http://hdl.handle.net/11566/263656.

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Lo scopo della ricerca è quello di analizzare i processi di co-creazione dei nuovi prodotti nel settore business-to-business. Lo studio si focalizza sull’analisi delle modalità con cui gli attori co-creano nuovi prodotti e di quali capacità di co-creazione possono essere utilizzate in queste interazioni per gestire nel modo migliore i processi di sviluppo prodotto. La letteratura in cui lo studio intende contribuire è quello connesso alle teorie di marketing sviluppate dall’IMP group, tramite l’analisi dei processi con cui le imprese riescono a co-creare nuovi prodotti all’interno del loro network di business. La letteratura utilizzata, oltre a quella derivante dagli studi di marketing industriale dell’IMP group, fa riferimento ai principali studi sullo sviluppo di nuovi prodotti, in termini di concettualizzazione e di definizione di un framework di sviluppo, e di concettualizzazione delle capacità di co-creazione che le imprese possono utilizzare per migliorare le loro interazioni durante lo sviluppo di nuovi prodotti. Lo studio è stato condotto secondo la metodologia del caso di studio singolo e longitudinale, con l’ausilio della tecnica del ‘systematic combining’ per l’analisi dei dati raccolti. L’impresa adottata come caso studio è Hyperlean, uno spin-off accademico, che ha sviluppato un software innovativo per design to cost e costing. Questa è stata scelta la sua potenziale unicità. Lo sviluppo del software, infatti, è avvenuto sin dall’inizio grazie alla collaborazione ed il sostegno da parte di diversi attori. La tesi si focalizza sull’analisi dei processi, e per questo, vengono descritti in termini di evidenze empiriche una serie di percorsi intrapresi dall’impresa e di capacità di co-creazione utilizzate dall’impresa. Infine, sono stati individuati anche alcuni lati oscuri e criticità che l’impresa ha dovuto fronteggiare durante il processo di sviluppo prodotto in co-creazione.
The aim of the research is to analyse new product development co-creation processes within industrial networks. The research is focused on the way actors of the business network co-create new products and on which co-creation capabilities these firm should use in order to succeed in these NPD processes. The manuscript aims to contribute to the IMP theory in industrial marketing, that is currently lacking empirical studies which provide thorough understanding of the interaction processes among firms within the industrial network in order to co-create new products. The studies conducted by IMP researchers represent also the main literature forming the theoretical background of the study, together with the NPD conceptualization and co-creation capabilities descriptions. The study adopts a single longitudinal case study methodology with systematic combining for depicting the findings. The case study analyses Hyperlean, which is an academic spin-off whose growth over time, in terms of product capabilities and revenues, is strongly tied to customers’ collaboration. Hyperlean has been chosen because of its potential uniqueness, that relies on the collaborations established with several big firms in order to develop the software by exploiting customers’ resources in terms of knowledge and technical information. This dissertation contributes to the literature by exploring the processes of new product development in co-creation between the case company and several actors of the business network and by identifying several different new product development co-creation pathways and co-creation capabilities deployed by Hyperlean in order to sustain commercialization activities. These findings revealed also several dark sides and critical issues within the processes under investigation.

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Ho, Elly Yi-Hsuan. „Impact of embeddedness in co-ethnic & non co-ethnic networks on business performance : evidence from Chinese immigrant entrepreneurs in Australia“. Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/39146/1/Elly_Ho_Thesis.pdf.

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This paper investigates the research question ‘What is the effect of co-ethnic and non coethnic networking on business performance in Chinese immigrant businesses?’ The research will discuss key themes such as the extent to which Chinese immigrant entrepreneurs are embedded in co-ethnic and non co-ethnic networks and the affect of embeddedness on business performance, such as the entrepreneur’s satisfaction and business growth. Research on immigrant entrepreneurship has emerged as an important new area of inquiry within the field of entrepreneurship. The increased importance of the subject is due in part to major immigrant receiving countries, such as Australia, the United States and Canada, experiencing a high growth rate in their immigrant population. Reflecting on the existing research on immigrant entrepreneurship, it was decided to investigate the role of embeddedness on entrepreneurial business performance. This research seeks to identify the impact of embeddedness in co-ethnic and non co-ethnic networks on business performance of Chinese immigrant entrepreneurs in Australia. Chinese immigrant restaurant entrepreneurs in southeast Queensland, Australia were studied. The result expands on existing research on immigrant entrepreneurship, since the majority of immigrant entrepreneurship studies have been conducted on the United States and Canada immigrant experiences, but few have been conducted in the Australian immigrant entrepreneur context. This thesis also adds empirical testing to a research area with little empirical testing. The results indicated that embeddedness in the co-ethnic network is positively related to business performance measured by both growth and satisfaction. Embeddedness in the non co-ethnic network of the Chinese immigrant entrepreneurs in Australia did not show a similar pattern in accordance with studies conducted in the United States and Canada. This result is interesting and creates the opportunity for future research employing a comparative study.

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Petereit, Julia. „Petal - A New Approach to Construct and Analyze Gene Co-Expression Networks in R“. Thesis, University of Nevada, Reno, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10248467.

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petal is a network analysis method that includes and takes advantage of precise Mathematics, Statistics, and Graph Theory, but remains practical to the life scientist. petal is built upon the assumption that large complex systems follow a scale-free and small-world network topology. One main intention of creating this program is to eliminate unnecessary noise and imprecision introduced by the user. Consequently, no user input parameters are required, and the program is designed to allow the two structural properties, scale-free and small-world, to govern the construction of network models.

The program is implemented in the statistical language R and is freely available as a package for download. Its package includes several simple R functions that the researcher can use to construct co-expression networks and extract gene groupings from a biologically meaningful network model. More advanced R users may use other functions for further downstream analyses, if desired.

The petal algorithm is discussed and its application demonstrated on several datasets. petal results show that the technique is capable of detecting biologically meaningful network modules from co-expression networks. That is, scientists can use this technique to identify groups of genes with possible similar function based on their expression information.

While this approach is motivated by whole-system gene expression data, the fundamental components of the method are transparent and can be applied to large datasets of many types, sizes, and stemming from various fields.

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Dillenburg, Fabiane Cristine. „An approach for analyzing and classifying microarray data using gene co-expression networks cycles“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/171353.

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Uma das principais áreas de pesquisa em Biologia de Sistemas refere-se à descoberta de redes biológicas a partir de conjuntos de dados de microarrays. Estas redes consistem de um grande número de genes cujos níveis de expressão afetam os outros genes de vários modos. Nesta tese, apresenta-se uma nova maneira de analisar os conjuntos de dados de microarrays, com base nos diferentes tipos de ciclos encontrados entre os genes das redes de co-expressão construídas com dados quantificados obtidos a partir dos microarrays. A entrada do método de análise é formada pelos dados brutos, um conjunto de genes de interesse (por exemplo, genes de uma via conhecida) e uma função (ativador ou inibidor) destes genes. A saída do método é um conjunto de ciclos. Um ciclo é um caminho fechado com todos os vértices (exceto o primeiro e o último) distintos. Graças à nova forma de encontrar relações entre os genes, é possível uma interpretação mais robusta das correlações dos genes, porque os ciclos estão associados a mecanismos de feedback, que são muito comuns em redes biológicas. A hipótese é que feedbacks negativos permitem encontrar relações entre os genes que podem ajudar a explicar a estabilidade do processo regulatório dentro da célula. Ciclos de feedback positivo, por outro lado, podem mostrar a quantidade de desequilíbrio de uma determinada célula em um determinado momento. A análise baseada em ciclos permite identificar a relação estequiométrica entre os genes da rede. Esta metodologia proporciona uma melhor compreensão da biologia do tumor. Portanto, as principais contribuições desta tese são: (i) um novo método de análise baseada em ciclos; (ii) um novo método de classificação; (iii) e, finalmente, aplicação dos métodos e a obtenção de resultados práticos. A metodologia proposta foi utilizada para analisar os genes de quatro redes fortemente relacionadas com o câncer - apoptose, glicólise, ciclo celular e NF B - em tecidos do tipo mais agressivo de tumor cerebral (Gliobastoma multiforme - GBM) e em tecidos cerebrais saudáveis. A maioria dos pacientes com GBM morrem em menos de um ano, essencialmente nenhum paciente tem sobrevivência a longo prazo, por isso estes tumores têm atraído atenção significativa. Os principais resultados nesta tese mostram que a relação estequiométrica entre genes envolvidos na apoptose, glicólise, ciclo celular e NF B está desequilibrada em amostras de GBM em comparação as amostras de controle. Este desequilíbrio pode ser medido e explicado pela identificação de um percentual maior de ciclos positivos nas redes das primeiras amostras. Esta conclusão ajuda a entender mais sobre a biologia deste tipo de tumor. O método de classificação baseado no ciclo proposto obteve as mesmas métricas de desempenho como uma rede neural, um método clássico de classificação. No entanto, o método proposto tem uma vantagem significativa em relação às redes neurais. O método de classificação proposto não só classifica as amostras, fornecendo diagnóstico, mas também explica porque as amostras foram classificadas de uma certa maneira em termos dos mecanismos de feedback que estão presentes/ausentes. Desta forma, o método fornece dicas para bioquímicos sobre possíveis experiências laboratoriais, bem como sobre potenciais genes alvo de terapias.
One of the main research areas in Systems Biology concerns the discovery of biological networks from microarray datasets. These networks consist of a great number of genes whose expression levels affect each other in various ways. We present a new way of analyzing microarray datasets, based on the different kind of cycles found among genes of the co-expression networks constructed using quantized data obtained from the microarrays. The input of the analysis method is formed by raw data, a set of interest genes (for example, genes from a known pathway) and a function (activator or inhibitor) of these genes. The output of the method is a set of cycles. A cycle is a closed walk, in which all vertices (except the first and last) are distinct. Thanks to the new way of finding relations among genes, a more robust interpretation of gene correlations is possible, because cycles are associated with feedback mechanisms that are very common in biological networks. Our hypothesis is that negative feedbacks allow finding relations among genes that may help explaining the stability of the regulatory process within the cell. Positive feedback cycles, on the other hand, may show the amount of imbalance of a certain cell in a given time. The cycle-based analysis allows identifying the stoichiometric relationship between the genes of the network. This methodology provides a better understanding of the biology of tumors. As a consequence, it may enable the development of more effective treatment therapies. Furthermore, cycles help differentiate, measure and explain the phenomena identified in healthy and diseased tissues. Cycles may also be used as a new method for classification of samples of a microarray (cancer diagnosis). Compared to other classification methods, cycle-based classification provides a richer explanation of the proposed classification, that can give hints on the possible therapies. Therefore, the main contributions of this thesis are: (i) a new cycle-based analysis method; (ii) a new microarray samples classification method; (iii) and, finally, application and achievement of practical results. We use the proposed methodology to analyze the genes of four networks closely related with cancer - apoptosis, glucolysis, cell cycle and NF B - in tissues of the most aggressive type of brain tumor (Gliobastoma multiforme – GBM) and in healthy tissues. Because most patients with GBMs die in less than a year, and essentially no patient has long-term survival, these tumors have drawn significant attention. Our main results show that the stoichiometric relationship between genes involved in apoptosis, glucolysis, cell cycle and NF B pathways is unbalanced in GBM samples versus control samples. This dysregulation can be measured and explained by the identification of a higher percentage of positive cycles in these networks. This conclusion helps to understand more about the biology of this tumor type. The proposed cycle-based classification method achieved the same performance metrics as a neural network, a classical classification method. However, our method has a significant advantage with respect to neural networks. The proposed classification method not only classifies samples, providing diagnosis, but also explains why samples were classified in a certain way in terms of the feedback mechanisms that are present/absent. This way, the method provides hints to biochemists about possible laboratory experiments, as well as on potential drug target genes.

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GARAU, MICHELE. „DEVELOPMENT OF CO-SIMULATION PLATFORMS FOR STATIC AND DYNAMIC ANALYSIS OF SMART DISTRIBUTION NETWORKS“. Doctoral thesis, Università degli Studi di Cagliari, 2018. http://hdl.handle.net/11584/255955.

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The development of the future energy system in accordance with the smart grid paradigm requires a radical change in the management of the electricity distribution network, which needs to become increasingly intelligent and adaptive. Smart distribution networks (SDN) will have systems in place to control a combination of distributed energy resources, and distribution system operators will be able to manage the electricity flows using a flexible network topology. The transition towards SDN involves software, automation and control systems, to ensure that the power distribution network not only remains within its operating limits (e.g. node voltages and branch currents within the acceptable thresholds), but also that it is operated in an optimal way. The SDN operation requires the extensive use of information and communication technology (ICT) and innovative control systems in order to enable the active management of DERs and expected growing number of electric vehicles. In SDN context, therefore, the ICT is not a simple add-on of the electrical system, but its availability and efficiency are essential to the operation of the entire power distribution system. In fact, the electric system will be managed and controlled through the communication network, which must guarantee a bidirectional exchange of large amount of data creating a keen interdependence between electric system and ICT system. The theme of the joint simulation of the electrical system and the communication infrastructure is becoming increasingly important in the scientific research on power systems. For planning the evolution towards the implementation of SDN, appropriate computing tools (not yet available among commercial software) should be developed to take into account the reciprocal interdependencies among the two systems. The co-simulation is the most common method for studying SDNs as a cyber-physical system (CPS), since it permits simulating each subsystem (electrical and ICT) simultaneously, and has represented the focus of this Ph. D. work. In this thesis different simulators specifically developed for co-simulation of smart distribution network analysis have been developed. They permit analyzing the slow dynamic operation of smart distribution networks (e.g. optimal power and reactive flow management, voltage regulation) as well the fast dynamic operation (e.g. fault management and reconfiguration). Different case studies have been investigated in order to show the effectiveness of the co-simulation platform features in analyzing the behavior of the smart distribution network in terms of capabilities, performances and reliability.

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Johansson, Peter. „Dynamic Co-authorship Network Analysis with Applications to Survey Metadata“. Thesis, Linnéuniversitetet, Institutionen för datavetenskap och medieteknik (DM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-96794.

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Co-authorship networks are a particular sort of social networks representing authors collaborating on joint publications. Such networks are studied within the fields of bibliometrics and scientometrics. While it is possible to analyze co-authorship networks in their entirety, certain analytical tasks would benefit from representing such networks as dynamic graphs, which incorporate a temporal dimension and capture structural transformations unfolding over time. The importance of dynamic graphs has emerged in recent years, in graph theory at large as well as within application domains such as social sciences, for instance.Research regarding dynamic graphs has been identified as one of the major challenges within network theory since they are particularly useful for describing real-world systems.This thesis project revolves around dynamic co-authorship network analysis algorithms, which aim to extract various temporal aspects regarding author collaborations.It is the result of a proposal by the ISOVIS group at Linnaeus University, which is active within the fields of exploratory data analysis and information visualization, including the problem of visual analysis of scientific publication data. The algorithms developed in this project extract analytical data such as (1) joint publications among pairs of authors, (2) temporal trends on connected components (groups of authors) along with network centrality measurements, and (3) major events regarding emergence, mergers, and splits of connected components over time. Together with domain experts, the analysis regarding usability, performance, and scalability of the algorithms took place as part of the evaluation process to assure that the result met the needs which instigated this thesis project. The application of the algorithms on real data sets provided by the ISOVIS group was useful concerning the evaluation of the usability domain. In contrast, customized synthetic data sets was an excellent tool for evaluating performance and scalability.

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Perez, Sarah Isa Esther. „Exploring microbial community structure and resilience through visualization and analysis of microbial co-occurrence networks“. Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53928.

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Cultivation independent microbial ecology research relies on high throughput sequencing technologies and analytical methods to resolve the infinite diversity of microbial life on Earth. Microorganisms live in communities driven by genetic and metabolic processes as well as symbiotic relationships. Interconnected communities of microorganisms provide essential functions in natural and human engineered ecosystems. Modelling the community as an inter-connected system can give insight into the community's functional characteristics related to the biogeochemical processes it performs. Network science resolves associations between elements of structure to notions of function in a system and has been successfully applied to the study of microbial communities and other complex biological systems. Microbial co-occurrence networks are inferred from community composition data to resolve structural patterns related to ecological properties such as community resilience to disturbance and keystone species. However, the interpretation of global and local network properties from an ecological standpoint remains difficult due to the complexity of these systems creating a need for quantitative analytical methods and visualization techniques for co-occurrence networks. This thesis tackles the visualization and analytical challenges of modelling microbial community structure from a network science approach. First, Hive Panel Explorer, an interactive visualization tool, is developed to permit data driven exploration of topological and data association patterns in complex systems. The effectiveness of Hive Panel Explorer is validated by resolving known and novel patterns in a model biological network, the C. elegans connectome. Second, network structural robustness analysis methods are applied to study microbial communities from timber harvested forest soils from a North American longterm soil productivity study. Analyzing these geographically dispersed soils reveals biogeographic patterns of diversity and enables the discovery of conserved organizing principles shaping microbial community structure. The capacity of robustness analysis to identify key microbial community members as well as model shifts in community structure due to environmental change is demonstrated. Finally, this work provides insight into the relationship between microbes and their ecosystem, and characterizing this relationship can help us understand the organization of microbial communities, survey microbial diversity and harness its potential.
Science, Faculty of
Graduate

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Arciniegas-Lopez, Maria Cristina. „Exploring scientific collaborations in geographical information science (GIScience) : a study of its co-authorship networks“. Thesis, City University London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440678.

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Charalabopoulos, Grigorios. „Radial basis function neural networks for channel equalization and co-channel interference cancellation in OFDM“. Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416116.

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Kwon, Woo Cheol. „Co-design of on-chip caches and networks for scalable shared-memory many-core CMPs“. Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118084.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 169-180).
Chip Multi-Processors(CMPs) have become mainstream in recent years, providing increased parallelism as core counts scale. While a tiled CMP is widely accepted to be a scalable architecture for the many-core era, on-chip cache organization and coherence are far from solved problems. As the on-chip interconnect directly influences the latency and bandwidth of on-chip cache, scalable interconnect is an essential part of on-chip cache design. On the other hand, optimal design of interconnect can be determined by the traffic forms that it should handle. Thus, on-chip cache organization is inherently interleaved with on-chip interconnect design and vice versa. This dissertation aims to motivate the need for re-organization of on-chip caches to leverage the advancement of on-chip network technology to harness the full potential of future many-core CMPs. Conversely, we argue that on-chip network should also be designed to support specific functionalities required by the on-chip cache. We propose such co-design techniques to offer significant improvement of on-chip cache performance, and thus to provide scalable CMP cache solutions towards future many-core CMPs. The dissertation starts with the problem of remote on-chip cache access latency. Prior locality-aware approaches fundamentally attempt to keep data as close as possible to the requesting cores. In this dissertation, we challenge this design approach by introducing new cache organization that leverages a co-designed on-chip network that allows multi-hop single-cycle traversals. Next, the dissertation moves to cache coherence request ordering. Without built-in ordering capability within the interconnect, cache coherence protocols have to rely on external ordering points. This dissertation proposes a scalable ordered Network-on-Chip which supports ordering of requests for snoopy cache coherence. Lastly, we describe development of a 36-core research prototype chip to demonstrate that the proposed Network-on-Chip enables shared-memory CMPs to be readily scalable to many-core platforms.
by Woo Cheol Kwon.
Ph. D.

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Hatem, Ayat. „Active Module Discovery: Integrated Approaches of Gene Co-Expression and PPI Networks and MicroRNA Data“. The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1398949621.

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Kar, Ar. „Corporate Co-evolution in State-Dominant Business Networks: the Case of the Myanmar Port Authority“. Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/81385.

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This study aims to extend knowledge of corporate co-evolution by drawing on the development trajectories that have taken place among government-business networks in the state-dominant business environment of Myanmar. From the perspectives of co-evolution, upper echelons, and business network, and through qualitative inquiry, this study addresses why and how organisations co-evolve with their environment, how upper echelons with military backgrounds influence corporate co-evolution, and how a public authority co-evolves with private actors in the industry.

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Silva, Maximiliano Barbosa da. „Redes sociais de colaboração acadêmica: tendências, determinantes e fricções do processo de formação de coautorias entre pesquisadores no Brasil“. Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/12/12138/tde-07112013-205540/.

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Nesta tese, estudam-se as tendências, os determinantes e as fricções do processo de formação de coautorias na produção de artigos acadêmicos entre pesquisadores no Brasil. Esta tarefa é dividida em três artigos. O primeiro artigo analisa a evolução temporal da incidência e da extensão de coautoria entre pesquisadores de diferentes campos do conhecimento. Os resultados obtidos confirmam a tendência, reportada na literatura, de crescimento do percentual de artigos coautorados e do número médio de autores por artigo. Em seguida, investigam-se os determinantes deste tipo de colaboração formal entre acadêmicos. Encontra-se que mulheres são mais propensas à coautoria do que homens, que trabalhos não puramente teóricos são mais propícios à colaboração e que a probabilidade de colaboração por parte de um pesquisador aumenta com o seu nível de dedicação em alguns campos do conhecimento. O segundo artigo estuda a evolução da rede social de coautoria em nove grandes áreas do conhecimento ao longo das últimas quatro décadas. Mostra-se que em quatro das nove grandes áreas do conhecimento analisadas, a rede social de coautoria pode ser considerada um mundo pequeno. Adicionalmente, ao decompor o processo de formação dos grafos de coautoria em seus componentes aleatórios e sociais, conclui-se que existem fricções significativas no pareamento de pesquisadores e que estas variam entre os campos do conhecimento, ao longo do tempo e entre populações de pesquisadores. O terceiro artigo investiga como a distância e o número de menores caminhos entre dois pesquisadores inseridos em uma rede social de coautoria afetam a probabilidade de que eles estabeleçam um elo de colaboração entre si. Oito grandes áreas do conhecimento são estudadas. Os resultados mostram que em quatro destes campos existem efeitos de proximidade em rede sobre a probabilidade de emergência de um novo link de coautoria e que estes efeitos são fortes. Além disto, a estratégia econométrica adotada permite concluir que estes efeitos decorrem do fluxo de informação sobre atributos individuais e qualidade de pareamentos passados através das redes de colaboração acadêmica. Além destas três contribuições principais, o capítulo introdutório desenvolve uma extensa revisão da literatura sobre redes econômicas e sociais com o objetivo de motivar o grande interesse da profissão pelo tema.
This dissertation studies the trends, determinants and frictions of the formation of coauthorship links among researchers in Brazil for the production of academic articles. This task is divided into three papers. The first paper studies the evolution over time of the incidence and extension of coauthorship among researchers in various fields of knowledge. The results confirm the trend of growth, reported in the literature, in the percentage of coauthored papers and in the average number of authors per paper. Next, the determinants of formal collaboration among academics are investigated. It is found that women are more inclined to collaborate than men, that non-purely theoretic papers are more collaboration prone and that the probability of collaboration is increasing with the number of hours devoted by an individual to research in some fields of knowledge. The second paper studies the evolution of the coauthorship network in nine broad fields of knowledge over the last four decades. It is shown that in four of the nine broad fields of knowledge analyzed, the coauthorship network can be considered a small world. In addition to that, by decomposing the network formation process into its random and social components, it can be concluded that there exist significant matching frictions among researchers and that they differ across fields, time and population. The third paper investigates how the distance and the number of shortest paths between two researchers in a coauthorship network affect the probability that they initiate a collaboration. Eight broad fields of knowledge are studied. The results show that in four of them there are social network proximity effects on the probability of the emergence of a new coauthorship link and that these effects are strong. Moreover, the econometric strategy permits to conclude that the effects result from the flow of information about individual attributes and about past matching quality through the links of the network of academic collaboration. In addition to these three main contributions, the introductory chapter presents an extensive review of the social and economic networks literature with the purpose of motivating the great interest on this subject.

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Zenoni, Beatrice. „Evaluating a co-creation model for social businesses: The case of ‘Linhas sobre rodas’“. Master's thesis, NSBE - UNL, 2013. http://hdl.handle.net/10362/9785.

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A Work Project, presented as part of the requirements for the Award of a Masters Degree in Management from the NOVA – School of Business and Economics
The following research is a critical evaluation of „Linhas sobre Rodas‟ co-creation process, since during my internship, from August to November 2012, I had the opportunity of directly and daily collaborate with the entities involved on the operationalization and implementation of this social business. The research analyses the key success factors of the „Linhas sobre Rodas‟ model during its initial stage, focusing on the stakeholders‟ relations and on the strategic alliance between the two co-creators. Through the evaluation of both strengths and weaknesses of this case study, the research provides recommendations and findings for similar cases.

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Kale, Mehmet Cemil. „Multispectral co-occurence analysis for medical image processing“. The Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1195500453.

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47

Campbell, Carlene. „An efficient multichannel wireless sensor networks MAC protocol based on IEEE 802.11 distributed co-ordinated function“. Thesis, Middlesex University, 2011. http://eprints.mdx.ac.uk/7913/.

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This research aimed to create new knowledge and pioneer a path in the area relating to future trends in the WSN, by resolving some of the issues at the MAC layer in Wireless Sensor Networks. This work introduced a Multi-channel Distributed Coordinated Function (MC-DCF) which takes advantage of multi-channel assignment. The backoff algorithm of the IEEE 802.11 distributed coordination function (DCF) was modified to invoke channel switching, based on threshold criteria in order to improve the overall throughput for wireless sensor networks. This work commenced by surveying different protocols: contention-based MAC protocols, transport layer protocols, cross-layered design and multichannel multi-radio assignments. A number of existing protocols were analysed, each attempting to resolve one or more problems faced by the current layers. The 802.15.4 performed very poorly at high data rate and at long range. Therefore 802.15.4 is not suitable for sensor multimedia or surveillance system with streaming data for future multichannel multi-radio systems. A survey on 802.11 DCF - which was designed mainly for wireless networks –supports and confirm that it has a power saving mechanism which is used to synchronise nodes. However it uses a random back-off mechanism that cannot provide deterministic upper bounds on channel access delay and as such cannot support real-time traffic. The weaknesses identified by surveying this protocol form the backbone of this thesis The overall aim for this thesis was to introduce multichannel with single radio as a new paradigm for IEEE 802.11 Distributed Coordinated Function (DCF) in wireless sensor networks (WSNs) that is used in a wide range of applications, from military application, environmental monitoring, medical care, smart buildings and other industry and to extend WSNs with multimedia capability which sense for instance sounds or motion, video sensor which capture video events of interest. Traditionally WSNs do not need high data rate and throughput, since events are normally captured periodically. With the paradigm shift in technology, multimedia streaming has become more demanding than data sensing applications as such the need for high data rate protocol for WSN which is an emerging technology in this area. The IEEE 802.11 can support data rates up to 54Mbps and 802.11 DCF was designed specifically for use in wireless networks. This thesis focused on designing an algorithm that applied multichannel to IEEE 802.11 DCF back-off algorithm to reduce the waiting time of a node and increase throughput when attempting to access the medium. Data collection in WSN tends to suffer from heavy congestion especially nodes nearer to the sink node. Therefore, this thesis proposes a contention based MAC protocol to address this problem from the inspiration of the 802.11 DCF backoff algorithm resulting from a comparison of IEEE 802.11 and IEEE 802.15.4 for Future Green Multichannel Multi-radio Wireless Sensor Networks.

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Douam, Florian. „Hepatitis C Virus E1E2 co-evolving networks unveil their functional dialogs and highlight original therapeutic strategies“. Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00946592.

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Hepatitis C Virus (HCV) infects more than 170 million people worldwide but no vaccine is available yet. HCV entry may represent a promising target for therapies and is mediated by two envelope glycoproteins, E1 and E2, assembled as heterodimer onto the virus surface. However, how E1 and E2 dialog, structurally rearrange and act together during these steps remain poorly defined. In this work, we aimed to clarify the interrelation of E1E2 during virus entry, thus opening ways to potential new therapeutic strategies. We first investigated whether a strong genetic divergence between E1E2 heterodimers may highlight distinct functions. We observed that B-cell derived E1E2 were specialized for B-cell infection, suggesting that new functions can emerge from the E1E2 conformational plasticity. In a second approach, we identified a conserved dialog between E1 and the domain III of E2 that was critical for virus binding and fusion. Moreover, a computational model predicted a strong co-evolution between E1 and E2 as well as potential structural rearrangements, suggesting that HCV E2 is likely a fusion protein able to fold over via its domain III through the mediation of E1. Altogether, these different works highlight that E1 and E2 are involved in complex dialogs that regulate the heterodimer folding and functions, suggesting that E1E2 heterodimer is more likely a single functional protein entity than an association of two proteins with specific functions.

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Tang, Yi. „SUNSHINE: Integrate TOSSIM and P-Sim“. Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/40721.

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Simulators are important tools for wireless sensor network (sensornet) design and evaluation. However, existing simulators only support evaluations of protocols and software aspects of sensornet design. Thus they cannot accurately capture the significant impacts of various hardware designs on sensornet performance. To fill in the gap, we proposed SUNSHINE, a scalable hardware-software cross-domain simulator for sensornet applications. SUNSHINE is the first sensornet simulator that effectively supports joint evaluation and design of sensor hardware and software performance in a networked context. SUNSHINE captures the performance of network protocols, software and hardware through the integration of two modules: a network simulator TOSSIM [1] and hardware-software simulator P-Sim composed of an instruction-set simulator SimulAVR [2] and a hardware simulator GEZEL [3]. This thesis focuses on the integration of TOSSIM and P-Sim. It discusses the integration design considerations and explains how to address several integration challenges: time conversion, data conversion, and time synchronization. Some experiments are also given to demonstrate SUNSHINEâ s cross-domain simulation capability, showing SUNSHINE's strength by integrating simulators from different domains.
Master of Science

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Uppalapati, Praneeth. „Network Mining Approach to Cancer Biomarker Discovery“. The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275405677.

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Dissertationen zum Thema „Co-Networks“

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