Tesi sul tema "Multidimensionnal network"
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1
Ben, Chaabene Nour El Houda. "Détection d'utilisateurs violents et de menaces dans les réseaux sociaux". Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAS001.
Abstract (sommario):
Les réseaux sociaux en ligne font partie intégrante de l'activité sociale quotidienne des gens. Ils fournissent des plateformes permettant de mettre en relation des personnes du monde entier et de partager leurs intérêts. Des statistiques récentes indiquent que 56% de la population mondiale utilisent ces médias sociaux. Cependant, ces services de réseau ont également eu de nombreux impacts négatifs et l'existence de phénomènes d'agressivité et d'intimidation dans ces espaces est inévitable et doit donc être abordée. L'exploration de la structure complexe des réseaux sociaux pour détecter les comportements violents et les menaces est un défi pour l'exploration de données, l'apprentissage automatique et l'intelligence artificielle. Dans ce travail de thèse, nous visons à proposer de nouvelles approches de détection des comportements violents dans les réseaux sociaux. Nos approches tentent de résoudre cette problématique pour plusieurs raisons pratiques. Premièrement, des personnes différentes ont des façons différentes d'exprimer le même comportement violent. Il est souhaitable de concevoir une approche qui fonctionne pour tout le monde en raison de la variété des comportements et des diverses manières dont ils sont exprimés. Deuxièmement, les approches doivent avoir un moyen de détecter les comportements anormaux potentiels non vus et de les ajouter automatiquement à l'ensemble d'apprentissage. Troisièmement, la multimodalité et la multidimensionnalité des données disponibles sur les sites de réseaux sociaux doivent être prises en compte pour le développement de solutions d'exploration de données qui seront capables d'extraire des informations pertinentes utiles à la détection de comportements violents. Enfin, les approches doivent considérer la nature variable dans le temps des réseaux pour traiter les nouveaux utilisateurs et liens et mettre automatiquement à jour les modèles construits. A la lumière de cela et pour atteindre les objectifs susmentionnés, les principales contributions de cette thèse sont les suivantes: - La première contribution propose un modèle de détection des comportements violents sur Twitter. Ce modèle prend en charge la nature dynamique du réseau et est capable d'extraire et d'analyser de données hétérogènes. - La deuxième contribution introduit une approche de détection des comportements atypiques sur un réseau multidimensionnel. Cette approche se base sur l'exploration et l'analyse des relations entre les individus présents sur cette structure sociale multidimensionnelle. - La troisième contribution présente un framework d'identification des personnes anormales. Ce cadre intelligent s'appuie sur l'exploitation d'un modèle multidimensionnel qui prend en entrée des données multimodales provenant de plusieurs sources, capable d'enrichir automatiquement l'ensemble d'apprentissage par les comportements violents détectés et considère la dynamicité des données afin de détecter les nouveaux comportements violents qui apparaissent sur le réseau. Cette thèse décrit des réalisations combinant les techniques d'exploration de données avec les nouvelles techniques d’apprentissage automatique. Pour prouver la performance de nos résultats d'expérimentation, nous nous sommes basés sur des données réelles extraites de trois réseaux sociaux populairesOnline social networks are an integral part of people's daily social activity. They provide platforms to connect people from all over the world and share their interests. Recent statistics indicate that 56% of the world's population use these social media. However, these network services have also had many negative impacts and the existence of phenomena of aggression and intimidation in these spaces is inevitable and must therefore be addressed. Exploring the complex structure of social networks to detect violent behavior and threats is a challenge for data mining, machine learning, and artificial intelligence. In this thesis work, we aim to propose new approaches for the detection of violent behavior in social networks. Our approaches attempt to resolve this problem for several practical reasons. First, different people have different ways of expressing the same violent behavior. It is desirable to design an approach that works for everyone because of the variety of behaviors and the various ways in which they are expressed. Second, the approaches must have a way to detect potential unseen abnormal behaviors and automatically add them to the training set. Third, the multimodality and multidimensionality of the data available on social networking sites must be taken into account for the development of data mining solutions that will be able to extract relevant information useful for the detection of violent behavior. Finally, approaches must consider the time-varying nature of networks to process new users and links and automatically update built models. In the light of this and to achieve the aforementioned objectives, the main contributions of this thesis are as follows: - The first contribution proposes a model for detecting violent behavior on Twitter. This model supports the dynamic nature of the network and is capable of extracting and analyzing heterogeneous data. - The second contribution introduces an approach for detecting atypical behaviors on a multidimensional network. This approach is based on the exploration and analysis of the relationships between the individuals present on this multidimensional social structure. - The third contribution presents a framework for identifying abnormal people. This intelligent framework is based on the exploitation of a multidimensional model which takes as input multimodal data coming from several sources, capable of automatically enriching the learning set by the violent behaviors detected and considers the dynamicity of the data in order to detect new violent behaviors that appear on the network. This thesis describes achievements combining data mining techniques with new machine learning techniques. To prove the performance of our experimental results, we sums based on real data taken from three popular social networks
2
Possamai, Lino <1978>. "Multidimensional analysis of complex networks". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5389/1/possamai_lino_tesi.pdf.
Abstract (sommario):
Complex Networks analysis turn out to be a very promising field of research, testified by many research projects and works that span different fields. Those analysis have been usually focused on characterize a single aspect of the system and a study that considers many informative axes along with a network evolve is lacking.
We propose a new multidimensional analysis that is able to inspect networks in the two most important dimensions, space and time. To achieve this goal, we studied them singularly and investigated how the variation of the constituting parameters drives changes to the network as a whole.
By focusing on space dimension, we characterized spatial alteration in terms of abstraction levels. We proposed a novel algorithm that, by applying a fuzziness function, can reconstruct networks under different level of details. We verified that statistical indicators depend strongly on the granularity with which a system is described and on the class of networks.
We keep fixed the space axes and we isolated the dynamics behind networks evolution process.
We detected new instincts that trigger social networks utilization and spread the adoption of novel communities. We formalized this enhanced social network evolution by adopting special nodes (called sirens) that, thanks to their ability to attract new links, were able to construct efficient connection patterns. We simulated the dynamics of the system by considering three well-known growth models.
Applying this framework to real and synthetic networks, we showed that the sirens, even when used for a limited time span, effectively shrink the time needed to get a network in mature state. In order to provide a concrete context of our findings, we formalized the cost of setting up such enhancement and provided the best combinations of system's parameters, such as number of sirens, time span of utilization and attractiveness.
3
Possamai, Lino <1978>. "Multidimensional analysis of complex networks". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5389/.
Abstract (sommario):
Complex Networks analysis turn out to be a very promising field of research, testified by many research projects and works that span different fields. Those analysis have been usually focused on characterize a single aspect of the system and a study that considers many informative axes along with a network evolve is lacking.
We propose a new multidimensional analysis that is able to inspect networks in the two most important dimensions, space and time. To achieve this goal, we studied them singularly and investigated how the variation of the constituting parameters drives changes to the network as a whole.
By focusing on space dimension, we characterized spatial alteration in terms of abstraction levels. We proposed a novel algorithm that, by applying a fuzziness function, can reconstruct networks under different level of details. We verified that statistical indicators depend strongly on the granularity with which a system is described and on the class of networks.
We keep fixed the space axes and we isolated the dynamics behind networks evolution process.
We detected new instincts that trigger social networks utilization and spread the adoption of novel communities. We formalized this enhanced social network evolution by adopting special nodes (called sirens) that, thanks to their ability to attract new links, were able to construct efficient connection patterns. We simulated the dynamics of the system by considering three well-known growth models.
Applying this framework to real and synthetic networks, we showed that the sirens, even when used for a limited time span, effectively shrink the time needed to get a network in mature state. In order to provide a concrete context of our findings, we formalized the cost of setting up such enhancement and provided the best combinations of system's parameters, such as number of sirens, time span of utilization and attractiveness.
4
Ringienė, Laura. "Hybrid neural network for multidimensional data visualization". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140912_140117-42267.
Abstract (sommario):
The area of research is data mining based on multidimensional data visual analysis. This allows researcher to participate in the process of data analysis directly, to understand the complex data better and to make the best decisions. The objective of the dissertation is to create a method for making a multidimensional data projection on the plane such that the researcher could see and assess the intergroup similarities and differences of multidimensional points. In order to achieve the target, a new hybrid neural network is proposed and investigated. This neural network integrates the ideas both of the radial basis function neural network and that of a multilayer perceptron, which has the properties of a ''bottleneck'' neural network. The new network is used for the visual analysis of multidimensional data in such a way that the output values of the neurons of the last hidden layer are the two-dimensional or three-dimensional projections of the multidimensional data, when the multidimensional data is given to the network. A peculiarity of the network is that the visualization results on the plane reflect the general structure of the data (clusters, proximity between clusters, intergroup similarities of points) rather than the location of multidimensional points.Šio darbo tyrimų sritis yra duomenų tyryba remiantis daugiamačių duomenų vizualia analize. Tai leidžia tyrėjui betarpiškai dalyvauti duomenų analizės procese, geriau pažinti sudėtingus duomenis ir priimti geriausius sprendimus. Disertacijos tikslas yra sukurti metodą tokios duomenų projekcijos radimui plokštumoje, kad tyrėjas galėtų pamatyti ir įvertinti daugiamačių taškų tarpgrupinius panašumus/skirtingumus. Šiam tikslui pasiekti yra pasiūlytas radialinių bazinių funkcijų ir daugiasluoksnio perceptrono, turinčio ,,butelio kaklelio“ neuroninio tinklo savybes, junginys. Naujas tinklas naudojamas vizualiai daugiamačių duomenų analizei, kai atidėjimui plokštumoje arba trimatėje erdvėje taškai gaunami paskutinio paslėpto neuronų sluoksnio išėjimuose, kai į tinklo įėjimą paduodami daugiamačiai duomenys. Šio tinklo ypatybė yra ta, kad gautas vaizdas plokštumoje labiau atspindi bendrą duomenų struktūrą (klasteriai, klasterių tarpusavio artumas, taškų tarpklasterinis panašumas) nei daugiamačių taškų tarpusavio išsidėstymą.
5
Zignani, M. "FROM SMALL-WORLDS TO BIG DATA:TEMPORAL AND MULTIDIMENSIONAL ASPECTS OF HUMAN NETWORKS". Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/233322.
Abstract (sommario):
In this thesis we address the close interplay among mobility, offline relationships and online interactions and the related human networks at different dimensional scales and temporal granularities. By generally adopting a data-driven approach, we move from small datasets about physical interactions mediated by human-carried devices, describing small social realities, to large-scale graphs that evolve over time, as well as from human mobility trajectories to face-to-face contacts occurring in different geographical contexts.
We explore in depth the relation between human mobility and the social structure induced by the overlapping of different people's trajectories on GPS traces collected in urban and metropolitan areas. We define the notions of geo-location and geo-community which are operational in describing in a unique framework both spatial and social aspects of human behavior. Through the concept of geo-community we model the human mobility adopting a bipartite graph. Thanks to this graph representation we can generate a social structure that is plausible w.r.t. the real interactions. In general the modeling approach have the merit for reporting the mobility in a graph-theoretic framework making the study of the interplay mobility/sociality more affordable and intuitive.
Our modeling approach also results in a mobility model, Geo-CoMM, which lies on and exploits the idea of geo-community. The model represents a particular instance of a general framework we provide. A framework where the social structure behind the preferred-location based mobility models emerges. We validate Geo-CoMM on spatial, temporal, pairwise connectivity and social features showing that it reproduces the main statistical properties observed in real traces.
As concerns the offline/online interplay we provide a complete overview of the close connection between online and offline sociality. To reach our goal we gather data about offline contacts and social interactions on Facebook of a group of students and we propose a multidimensional network analysis which allows us to deeply understand how the characteristics of users in the distinct networks impact each other. Results show how offline and Facebook friends are different. This way we confirm and worsen the general intuition that online social networks have shifted away from their original goal to mirror the offline sociality of individuals. As for the role and the social importance, it becomes apparent that social features such as user popularity or community structure do not transfer along social dimensions, as confirmed by our correlation analysis of the network layers and by the comparison among the communities.
In the last chapters we analyze the evolution of the online social network from a physical time perspective, i.e. considering the graph evolution as a graph time-series and not as a function of the network basic properties (number of nodes or links).
As for the physical time in a user-centric viewpoint, we investigate the bursty nature of the link creation process in online social network. We prove not only that it is a highly inhomogeneous process, but also identify patterns of burstiness common to all nodes. Then we focus on the dynamic formation of two fundamental network building components: dyads and triads. We propose two new metrics to aid the temporal analysis on physical time: link creation delay and triangle closure delay. These two metrics enable us to study the dynamic creation of dyads and triads, and to highlight network behavior that would otherwise remain hidden. In our analysis, we find that link delays are generally very low in absolute time and are largely independent of the dates people join the network. To highlight the social nature of this metric, we introduce the term \textit{peerness} to quantify how well linked users overlap in lifetimes. As for triadic closure delay we first introduce an algorithm to extract of temporal triangle which enables us to monitor the triangle formation process, and to detect sudden changes in the triangle formation behavior, possibly related to external events. In particular, we show that the introduction of new service functionalities had a disruptive impact on the triangle creation process in the network.
6
Li, Yan. "Multidimensional protein separations in a plastic microfluidic network". College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/194.
Abstract (sommario):
Thesis (Ph. D.)--University of Maryland, College Park, 2003.Thesis research directed by: Chemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
7
Suh, Young-Joo. "Realizations of efficient collective communication in multidimensional processor arrays". Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/13343.
8
Tulabandula, Sridhar. "Localization of wireless sensor networks using multidimensional scaling". Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4986.
Abstract (sommario):
Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 17, 2008) Includes bibliographical references.
9
Sumanasena, M. G. Buddika. "A multidimensional systems approach to grid sensor networks". Thesis, University of Notre Dame, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3578994.
Abstract (sommario):
A method for distributed information processing in rectangular grid based wireless sensor networks is presented, employing the Givone-Roesser and the Fornasini-Marchesini state space models for m-D systems. It can be used for distributed implementation of any general linear system on a grid sensor network. The method is highly scalable and requires only communication between immediate neighbors.
Usage of finite precision schemes for the representation of numbers and computations introduce nonlinearities to the otherwise linear m-D system models. Nonlinearities caused by fixed point and floating point number representation schemes used for in node computations and inter-node communication are modeled. Stability of the system is analyzed with special consideration given to the influence of inter-node communication on system dynamics. Necessary and sufficient conditions for the global asymptotic stability under both fixed point and floating point arithmetic is derived. It has been shown that the global asymptotic stability of the sensor networks is equivalent to that of a 1-D system for both the cases of fixed point and floating number representation.
Issues posed by communication time delay, in real-time implementation of the proposed method, are discussed. It is shown that, in order to implement a real-time sensor network, system matrices of the state space models have to satisfy certain conditions. A necessary and sufficient condition for a transfer function to be realizable in the constrained state space models is established. Realization algorithms to derive state space models of the desired form given an admissible transfer function are also presented. Node and link failure introduce complications not encountered in centralized implementation of m-D systems. Givone-Roesser and the Fornasini-Marchesini state space models are extended to include node and link failure. Necessary and sufficient conditions for mean square stability are then derived with the help of these two state space models. Input output stability of the distributed systems under node and link failure is also discussed.
The utility of the proposed method is demonstrated by examples. In particular a distributed Kalman filter is proposed for grid sensor networks. Implementation of the proposed Kalman filter on grid sensor networks is discussed in some detail. A method for contaminant detection and its implementation using the proposed method is also presented.
10
Ahmed, Ahmed Abdol-Monem. "Experimental study of localization in sensor networks and design of adaptive localization". Diss., Columbia, Mo. : University of Missouri-Columbia, 2005. http://hdl.handle.net/10355/5829.
Abstract (sommario):
Thesis (Ph.D.)--University of Missouri-Columbia, 2005.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (Novembr 15, 2006) Vita. Includes bibliographical references.
11
Esfandyari, A. "MULTIDIMENSIONAL ANALYSIS OF PEOPLE'S BEHAVIOR IN ONLINE SOCIAL NETWORKS". Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/470004.
Abstract (sommario):
L’impressionante crescita in popolarità delle Online Social Networks (OSNs), evidenziata dall’enorme numero di utenti oggi legati ai social network più popolari, offre un’opportunità unica per comprendere i comportamenti online degli individui.
In questa tesi, analizziamo i comportamenti delle persone sulle OSNs considerando che tali comportamenti sono il risultato della combinazione di esperienze ed attitudini sia online che offline.
Dapprima, eseguiamo una analisi multidimensionale degli utenti attraverso diversi social media per fornire una descrizione complessiva dei comportamenti online e comprendere come questi cambino quando più media sono disponibili contemporaneamente. I risultati che presentiamo rappresentano uno dei primi esempi di esplorazione dei comportamenti umani su diversi social media. Ad esempio, utilizzando lo user degree su 5 diversi social network, evidenziamo che l’importanza di ogni individuo cambia da piattaforma a piattaforma. La natura longitudinale del nostro dataset è anche stata sfruttata per studiare l’attività di posting degli utenti, evidenziando una leggera correlazione positiva sulla frequenza con cui gli utenti pubblicano su social media differenti e confermando la natura bursty delle attività di posting mediante l’uso di serie temporali multidimensionali.
Inoltre, durante la tesi abbiamo sviluppato un metodo di identificazione innovativo per collegare le persone attraverso le diverse piattaforme social. Facendo riferimento agli attributi pubblici comuni, attraverso l’uso di application programming interface (API) dei diversi social network, costruiamo le istanze negative in tre modi diversi, superando la selezione randomica abitualmente adottata, allo scopo di valutare la robustezza del nostro algoritmo di identificazione su diversi dataset. I risultati mostrano che l’approccio porta ad un metodo di identificazione molto efficace per costruire dataset affidabili. Uno scenario reale costruito su Google+ e Facebook è stato utilizzato come testbed per la validazione del metodo. I risultati che riportiamo dimostrano i vantaggi ottenibili con il nuovo metodo rispetto ad altri metodi da letteratura.
Infine, la tesi compie un primo passo verso una miglior comprensione degli effetti degli eventi offline sulla struttura del grafo delle social network in cui sono pubblicizzati. Più precisamente, svolgiamo una analisi temporale della social network legata all’evento, comprendendo le persone che dichiarano di partecipare all’evento tramite facebook, e valutiamo come questa evolva durante l’intervallo temporale dell’eventi stesso. I risultati mostrano che nuove amicizie nascono durante l’evento e che la creazione di questi nuovi legami sociali è una delle cause principali di chiusura triangolare e che il grado maggiore si osserva durante l’ultimo giorno dell’evento stesso.The unprecedented and quickly increasing popularity of Online Social Networks (OSNs) is evidenced by the huge number of users who are turning to Facebook, Twitter and other social networks. The rapid growth of these online social networks provides a unique chance to study and understand the online behavior of the people. In this thesis, we analyze people's behavior in online social network considering the fact that online behavior of people is influenced by different factors which derive from the combination of their offline and online life. First, we perform a multidimensional analysis of users across multiple social media sites to give an all-around picture of people’s online behavior. While people in their online life have access to a wide portfolio of social platforms, little is known about users’ behavior when they have different online communication media available. Our findings represent some novel insights about people’s behavior across social media. Having at our disposal users’ degree in five different social networks, we find that the individuals’ importance changes from medium to medium. The longitudinal nature of our dataset has been exploited to investigate the posting activity. We find a slightly positive correlation on how often users publish on different social media and we confirm the burstiness of the posting activities extending it to multidimensional time-series. Second, we develop an innovative identification methodology for connecting people across multiple social platforms. Relying on common public attributes available through the official application programming interface (API) of social networks, we construct negative instances in three different ways, going beyond the commonly adopted random selection to evaluate the robustness of our identification algorithm on different datasets. Results show that the approach can lead to a very effective identification method and methodology for building reliable datasets. Moreover, we analyzed the success of our method in a real scenario built on Google+/Facebook neighborhoods. Experiments reveal the advantages of the proposed method in comparison to previous methods in the literature. Finally, we take the first step towards understanding the effect of offline events on the graph structure of the social network where they are advertised. More precisely, we perform a temporal analysis of the event social network, constituted by people declaring to attend the event on Facebook and the links between them, and evaluated how it evolves during the event time period. The results show that new friendships are created during events and that this new friendships creation is one of the main reasons of triangle closure and the higher degrees observed in the last day of the events period.
12
Medvedev, Viktor. "Research of multidimensional data visualization using feed-forward neural networks". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080204_162417-59477.
Abstract (sommario):
The research area of this work is the analysis of multidimensional data and the ways of improving apprehension of the data. Data apprehension is rather a complicated problem especially if the data refer to a complex object or phenomenon described by many parameters. The research object of the dissertation is artificial neural networks for multidimensional data projection. General topics that are related with this object: multidimensional data visualization; dimensionality reduction algorithms; errors of projecting data; the projection of the new data; strategies for retraining the neural network that visualizes multidimensional data; optimization of control parameters of the neural network for multidimensional data projection; parallel computing. The key aim of the work is to develop and improve methods how to efficiently minimize visualization errors of multidimensional data by using artificial neural networks. The results of the research are applied in solving some problems in practice. Human physiological data that describe the human functional state have been investigated.Disertacijos tyrimų sritis yra daugiamačių duomenų analizė, bei tų duomenų suvokimo gerinimo būdai. Duomenų suvokimas yra sudėtingas uždavinys, ypač kai duomenys nurodo sudėtingą objektą, kuris aprašytas daugeliu parametrų. Disertacijoje nagrinėjami dirbtinių neuroninių tinklų algoritmai daugiamačiams duomenims vizualizuoti. Darbo tyrimų objektas yra dirbtiniai neuroniniai tinklai, skirti daugiamačių duomenų vizualizavimui. Su šiuo objektu yra betarpiškai susiję dalykai: daugiamačių duomenų vizualizavimas; dimensijos mažinimo algoritmai; projekcijos paklaidos; naujų taškų atvaizdavimas; vizualizavimui skirto neuroninio tinklo permokymo strategijos ir parametrų optimizavimas; lygiagretieji skaičiavimai. Pagrindinis disertacijos tikslas yra sukurti ir tobulinti metodus, kuriuos taikant būtų efektyviai minimizuojamos daugiamačių duomenų projekcijos paklaidos naudojantis dirbtiniais neuroniniais tinklais bei projekcijos algoritmais. Darbe atliktų tyrimų rezultatai atskleidė naujas medicininių (fiziologinių) duomenų analizės galimybes.
13
Mair, Patrick, Thomas Rusch e Kurt Hornik. "The grand old party - a party of values?" Springer, 2014. http://dx.doi.org/10.1186/2193-1801-3-697.
Abstract (sommario):
In this article we explore the semantic space spanned by self-reported statements of Republican voters. Our semantic structure analysis uses multidimensional scaling and social network analysis to extract, explore, and visualize word patterns and word associations in response to the stimulus statement "I'm a Republican, because ..." which were collected from the official website of the Republican Party. With psychological value theory as our backdrop, we examine the association of specific keywords within and across the statements, compute clusters of statements based on these associations, and explore common word sequences Republican voters use to characterize their political association with the Party. (authors' abstract)
14
O'Neill, Jason Michael. "Multidimensional Mass Spectrometry Studies on Amphiphilic Polymer Blends and Cross-Linked Networks". University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1624375174939496.
15
Langer, Max. "Design of Fast Multidimensional Filters by Genetic Algorithms". Thesis, Linköping University, Department of Biomedical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2704.
Abstract (sommario):
The need for fast multidimensional signal processing arises in many areas. One of the more demanding applications is real time visualization of medical data acquired with e.g. magnetic resonance imaging where large amounts of data can be generated. This data has to be reduced to relevant clinical information, either by image reconstruction and enhancement or automatic feature extraction. Design of fast-acting multidimensional filters has been subject to research during the last three decades. Usually methods for fast filtering are based on applying a sequence of filters of lower dimensionality acquired by e.g. weighted low-rank approximation. Filter networks is a method to design fast multidimensional filters by decomposing multiple filters into simpler filter components in which coefficients are allowed to be sparsely scattered. Up until now, coefficient placement has been done by hand, a procedure which is time-consuming and difficult. The aim of this thesis is to investigate whether genetic algorithms can be used to place coefficients in filter networks. A method is developed and tested on 2-D filters and the resulting filters have lower distortion values while still maintaining the same or lower number of coefficients than filters designed with previously known methods.
16
Kettemann, Anita Stefanie. "Mathematical modelling and numerical simulation of chemosensitive cell dynamics in multidimensional tissue networks". Aachen Shaker, 2009. http://d-nb.info/1001048598/04.
17
Sitte, André, Oliver Koch, Jianbin Liu, Ralf Tautenhahn e Jürgen Weber. "Multidimensional flow mapping for proportional valves". Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71093.
Abstract (sommario):
Inverse, multidimensional input-output flow mapping is very important for use of valves in precision motion control applications. Due to the highly nonlinear characteristic and uncertain model structure of the cartridge valves, it is hard to formulate the modelling of their flow mappings into simple parameter estimation problems. This contribution conducts a comprehensive analysis and validation of three- and four-dimensional input-output-mapping approaches for a proportional pilot operated seat valves. Therefore, a virtual and a physical test-rig setup are utilized for initial measurement, implementation and assessment. After modeling and validating the valve under consideration, as a function of flow, pressure and temperature different mapping methods are investigated. More specifically, state of the art approaches, deep-learning methods and a newly developed approach (extPoly) are examined. Especially ANNs and Polynomials show reasonable approximation results even for more than two inputs. However, the results are strongly dependent on the structure and distribution of the input data points. Besides identification effort, the invertibility was investigated.
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Sourty, Marion. "Analyse de la dynamique temporelle et spatiale des réseaux cérébraux spontanés obtenus en imagerie par résonance magnétique fonctionnelle". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAD002/document.
Abstract (sommario):
L’imagerie par résonance magnétique fonctionnelle (IRMf) est un outil de choix pour cartographier d’une manière non invasive l’activité du cortex, donnant ainsi un accès à l’organisation fonctionnelle cérébrale. Cette organisation des aires cérébrales en réseaux complexes reste encore un vaste sujet d’étude, autant dans le domaine de la recherche fondamentale, pour mieux comprendre le développement et le fonctionnement du cerveau, que dans le domaine clinique, à des fins diagnostiques par exemple. Les réseaux cérébraux dits de repos, chez un sujet donné, peuvent être observés lors d’études IRMf lorsqu’aucune tâche motrice ou cognitive n’est imposée au sujet imagé. La première partie de cette thèse a permis le développement d’une méthode automatique d’identification de ces réseaux. Réalisée à l’échelle du sujet, cette méthode permet de sélectionner tous les réseaux spécifiques au sujet ce qui s’avère nécessaire dans un cadre diagnostique où l’individu prime. Au delà de la détection et de l’identification de ces réseaux, l’étude de leurs modes d’interaction dans l’espace et dans le temps et plus généralement l’analyse de la dynamique de la connectivité fonctionnelle (DCF) fait l’objet d’un intérêt grandissant. Cette analyse nécessite le développement de méthodes innovantes de traitement du signal et de l’image qui, pour l’heure, sont encore de nature exploratoire. La deuxième partie de cette thèse présente donc de nouvelles approches pour caractériser la DCF en utilisant le cadre probabiliste de modèles de Markov cachés multidimensionnels. Les mécanismes conversationnels entre réseaux cérébraux peuvent ainsi être identifiés et caractérisés à l’échelle de la seconde. Deux applications, au niveau du sujet puis du groupe, ont permis de mettre en avant les modifications des propriétés dynamiques des interactions entre réseaux sous certaines conditions ou pathologiesThe functional magnetic resonance imaging (fMRI) is a perfect tool for mapping in a non- invasive manner the activity of the cortex, giving access to the functional organization of the brain. This organization of brain areas into complex networks remains a large topic of study, both from a fundamental research perspective, to better understand the development and function of the brain, and from a clinical perspective, for diagnostic purposes for instance. The resting-state networks in a given subject can be observed in fMRI studies where no motor or cognitive tasks are imposed to the subject. The first part of this thesis focused on the development of an automatic identification method of these networks. Performed at the subject level, this method selects all the resting-state networks proper to the subject. Beyond the detection and identification of these networks, the study of interactions between these networks in space and time, and more generally the analysis of the dynamic functional connectivity (DFC), is the subject of growing interest. This analysis requires the development of innovative methods of signal or image processing that, for now, are still exploratory. The second part of this thesis thus presents new approaches to characterize the DFC using the probabilistic framework of multidimensional hidden Markov models. Conversational mechanisms between brain networks can be identified and characterized at the resolution of the second. Two applications, first on a single subject then on a group, helped to highlight the changes of dynamic properties of interaction between networks under certain conditions or diseases
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Kodali, Lata. "Extensions of Weighted Multidimensional Scaling with Statistics for Data Visualization and Process Monitoring". Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99911.
Abstract (sommario):
This dissertation is the compilation of two major innovations that rely on a common technique known as multidimensional scaling (MDS). MDS is a dimension-reduction method that takes high-dimensional data and creates low-dimensional versions.
Project 1: Visualizations are useful when learning from high-dimensional data. However, visualizations, just as any data summary, can be misleading when they do not incorporate measures of uncertainty; e.g., uncertainty from the data or the dimension reduction algorithm used to create the visual display. We incorporate uncertainty into visualizations created by a weighted version of MDS called WMDS. Uncertainty exists in these visualizations on the variable weights, the coordinates of the display, and the fit of WMDS. We quantify these uncertainties using Bayesian models in a method we call Informative Probabilistic WMDS (IP-WMDS). Visually, we display estimated uncertainty in the form of color and ellipses, and practically, these uncertainties reflect trust in WMDS. Our results show that these displays of uncertainty highlight different aspects of the visualization, which can help inform analysts.
Project 2: Analysis of network data has emerged as an active research area in statistics. Much of the focus of ongoing research has been on static networks that represent a single snapshot or aggregated historical data unchanging over time. However, most networks result from temporally-evolving systems that exhibit intrinsic dynamic behavior. Monitoring such temporally-varying networks to detect anomalous changes has applications in both social and physical sciences. In this work, we simulate data from models that rely on MDS, and we perform an evaluation study of the use of summary statistics for anomaly detection by incorporating principles from statistical process monitoring. In contrast to most previous studies, we deliberately incorporate temporal auto-correlation in our study. Other considerations in our comprehensive assessment include types and duration of anomaly, model type, and sparsity in temporally-evolving networks. We conclude that the use of summary statistics can be valuable tools for network monitoring and often perform better than more involved techniques.Doctor of Philosophy
In this work, two main ideas in data visualization and anomaly detection in dynamic networks are further explored. For both ideas, a connecting theme is extensions of a method called Multidimensional Scaling (MDS). MDS is a dimension-reduction method that takes high-dimensional data (all $p$ dimensions) and creates a low-dimensional projection of the data. That is, relationships in a dataset with presumably a large number of dimensions or variables can be summarized into a lower number of, e.g., two, dimensions. For a given data, an analyst could use a scatterplot to observe the relationship between 2 variables initially. Then, by coloring points, changing the size of the points, or using different shapes for the points, perhaps another 3 to 4 more variables (in total around 7 variables) may be shown in the scatterplot. An advantage of MDS (or any dimension-reduction technique) is that relationships among the data can be viewed easily in a scatterplot regardless of the number of variables in the data. The interpretation of any MDS plot is that observations that are close together are relatively more similar than observations that are farther apart, i.e., proximity in the scatterplot indicates relative similarity. In the first project, we use a weighted version of MDS called Weighted Multidimensional Scaling (WMDS) where weights, which indicate a sense of importance, are placed on the variables of the data. The problem with any WMDS plot is that inaccuracies of the method are not included in the plot. For example, is an observation that appears to be an outlier, really an outlier? An analyst cannot confirm this without further context. Thus, we created a model to calculate, visualize, and interpret such inaccuracy or uncertainty in WMDS plots. Such modeling efforts help analysts facilitate exploratory data analysis. In the second project, the theme of MDS is extended to an application with dynamic networks. Dynamic networks are multiple snapshots of pairwise interactions (represented as edges) among a set of nodes (observations). Over time, changes may appear in some of the snapshots. We aim to detect such changes using a process monitoring approach on dynamic networks. Statistical monitoring approaches determine thresholds for in-control or expected behavior that are calculated from data with no signal. Then, the in-control thresholds are used to monitor newly collected data. We applied this approach on dynamic network data, and we utilized a detailed simulation study to better understand the performance of such monitoring. For the simulation study, data are generated from dynamic network models that use MDS. We found that monitoring summary statistics of the network were quite effective on data generated from these models. Thus, simple tools may be used as a first step to anomaly detection in dynamic networks.
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Deleskog, Viktor. "Sensor Localization Calibration of Ground Sensor Networks with Acoustic Range Measurements". Thesis, Linköpings universitet, Reglerteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81655.
Abstract (sommario):
Advances in the development of simple and cheap sensors give new possibilities with large sensor network deployments in monitoring and surveillance applications. Commonly, the sensor positions are not known, specifically, when sensors are randomly spread in a big area. Low cost sensors are constructed with as few components as possible to keep price and energy consumption down. This implies that self-positioning and communication capabilities are low. So the question: “How do you localize such sensors with good precision with a feasible approach?” is central. When no information is available a stable and robust localization algorithm is needed. In this thesis an acoustic sensor network is considered. With a movable acoustic source a well-defined and audible signal is transmitted at different spots. The sensors measure the time of arrival which corresponds to distance. A two-step sensor localization approach is applied that utilizes the estimated distances. A novel approach in the first step is presented to incorporate more measurements and gain more position information. Localization and ranging performance is evaluated with simulations and data collected at field trials. The results show that the novel approach attains higher accuracy and robustness.
21
Kremer, Marius Verfasser], Ullrich [Akademischer Betreuer] [Englert e Manfred [Akademischer Betreuer] Martin. "Exploring dicarboxylic acids as ligands in multidimensional coordination networks / Marius Kremer ; Ulli Englert, Manfred Martin". Aachen : Universitätsbibliothek der RWTH Aachen, 2020. http://d-nb.info/1230322922/34.
22
Kettemann, Anita S. [Verfasser]. "Mathematical modelling and numerical simulation of chemosensitive cell dynamics in multidimensional tissue networks / Anita S Kettemann". Aachen : Shaker, 2010. http://d-nb.info/1124364048/34.
23
Fernández-Carro, Celia. "‘Ageing in Place’ in Europe: A multidimensional approach to independent living in later life". Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129081.
Abstract (sommario):
En las sociedades occidentales, el aumento de la longevidad ha significado la prolongación del tiempo que las personas mayores viven en sus propios domicilios. Ya sea de facto o por elección consciente, la realidad es la gran mayoría de las personas mayores permanencen en sus viviendas particulares hasta que el traslado a una institución de cuidados es inevitable por graves deficiencias en el estado de salud. Esta experiencia habitacional, el hecho de permanecer en casa durante la vejez, ha sido conceptualizado bajo el nombre de Ageing in Place.
Esta tesis doctoral utiliza el potencial teórico del concepto de ‘Ageing in Place’ para analizar el proceso de adaptación de los mayores (población de 65 años y más) a su entorno. El explorar cómo se produce, que características tiene, qué tipos existen y que mecanismos lo facilitan, tanto a nivel individual como estructural, es el principal objetivo de este trabajo. Dado que ‘Ageing in Place’ ha servido a la vez como guía para la investigación sobre las condiciones de vida de los mayores (acepción ligada al ámbito académico) y como término mainstream para designar aquellas políticas en materia social residencial y de cuidados (acepción del ámbito político-institucional), los debates surgidos de esa dicotomía son parte central de este trabajo. En definitiva, esta tesis se pregunta ¿Qué es ‘Ageing in Place’? y ¿Cuáles son los factores que condicionan su consecución?.
Enmarcada en el contexto Europeo (la tesis hace un análisis comparativo de todos o algunos países –dependiendo el capítulo- de la UE15), esta tesis se centra en explorar cuatro de los componentes que condicionan experiencia de Ageing in Place. El estudio del componente demográfico caracteriza a aquellos mayores que permanecen en sus viviendas cuantificando la magnitud del fenómeno. El análisis del componente residencial describe las condiciones habitacionales de los mayores Europeos, analiza cómo estas influyen en su satisfacción residencial, además de explorar los tipos de estrategias residenciales utilizadas por los mayores a través la dicotomía movilidad-permanencia. El componente social, un pilar básico en la consecución del Ageing in Place, analiza los mecanismos de apoyo tanto formales como informales, que permiten a los mayores compensar la posible pérdida de funcionalidad debido a la edad. En este sentido, el papel de la familia como proveedora de cuidados es esencial y por eso constituye un eje central el análisis. Por último, el componente individual, investiga a cerca de los factores que influyen las preferencias de los mayores en lo relativo al lugar donde desean pasar sus años de vejez; en la casa propia, en la casa de un familiar o en una institución de cuidados.
Las dos principales fuentes estadísticas de esta tesis son de ámbito europeo; Survey of Ageing, Retirement and Health in Europe (SHARE) y la Encuesta Europea de Condiciones de Vida (EU-SILC), permiten hacer una comparativa entre distintos países Europeos. El objetivo es testar si el eje Norte-Sur que dibujan tanto el tipo de organización del Estado del Bienestar como los rasgos culturales que condicionan las relaciones familiares influencian la manera en que Ageing in Place es llevado a cabo en las distintas regiones del continente. El análisis empírico se realiza mediante técnicas multivariantes que van desde la regresión logística hasta distintas aplicaciones de los modelos Logit y Probit.
Los resultados obtenidos invitan a reflexionar sobre la vejez, las nuevas identidades de los mayores, y los discursos generados en torno al envejecimiento demográfico. Este trabajo también contribuye al debate sobre el papel que la familia y los estados tienen en la provisión de cuidados a los mayores dependientes subrayando las importantes diferencias existentes dentro del contexto Europeo.In the industrialised countries, the longevity increase has lead into the extension of the time that elderly people remain in their homes. Whether de facto or by election, the reality is that the vast majority of older people are living in a private accommodation until a severe decline in health status forces a move towards a nursing institution. This experience, the fact to remain at home in later life, has been conceptualised as ‘Ageing in Place’ or ‘Independent Living’. This thesis has utilised the ‘ageing in place’ concept to explore the multidimensional relationship among older people and their living environment that permit them to remain at home despite changes in their living conditions due to ageing process. The aim has been to analyse how independent living is attained, what are its caracteristics and strategies that shape its development, and what the mechanisms enhance it. Given that ‘Ageing in Place’ notion have been used simoutanoeusly in the scientific field and in the institutional ambit, that has convert it in the mainstrean term under which present the social, care and housing policies in Europe, the emergents debates from this dichotomy are a central part of this investigation. All in all, the questions that this thesis sets out are “what we are talking about when we talk about ageing in place’ and “which factors that condition the ageing in palce experience?”. Focused in the European context, this thesis performs a cross-national analysis among the EU15 countries, exploring four components of Ageing in Place experience. The study of the demographic component aims to caractherise the profiles of those elderly people that remain living at home, quantifiying the magnitude of the phenomenon and highlighting the similarities and divergences among regions. The residential component analyse the living conditions of older Europeans, besides to analyse to what extent these conditions shape the residential satisfaction in later life. The social component of Ageing in Place is analysed idetifiying the support mechanisms, both formal or informal, that help older people to remain living in their own home. The role of family networks is essential in care provission, reason why family ties is a core aspect of the analysis. This thesis also aims to shed light on the individual component of ageing in place, investigating about the aspects that condition the ideal images that older people maintain about the best enviroment to growing older; in the own home, co-residing with a relative or in an institution. The spatial scope of this last analysis only consider one country: Spain. The two main data sources used are cross-European: Survey of Ageing, Retirement and Health in Europe (SHARE) and the European Union Statistics of Income and Living Conditions (EU-SILC), allowing the cross-national perspective. The objective is to assess if the North-South gradient based in the development of welfare states and the socio-cultural diversity in family relationships determine the way older people is ageing at home in the different regions of the continent. The empirical analysis is developed by means of multivariate techniques, from Logistic Regression models, to distinct applications of Discrete Choice Models, as Logit or Probit. The empirical results obtained invite to reflect about ageing, the new identities of older people and the discourses generated by demographic change. This work also contributes to the debate about the role that families and states have on well-being in later life.
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Shabut, Antesar Ramadan M. "Trust computational models for mobile ad hoc networks : recommendation based trustworthiness evaluation using multidimensional metrics to secure routing protocol in mobile ad hoc networks". Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/7501.
Abstract (sommario):
Distributed systems like e-commerce and e-market places, peer-to-peer networks, social networks, and mobile ad hoc networks require cooperation among the participating entities to guarantee the formation and sustained existence of network services. The reliability of interactions among anonymous entities is a significant issue in such environments. The distributed entities establish connections to interact with others, which may include selfish and misbehaving entities and result in bad experiences. Therefore, trustworthiness evaluation using trust management techniques has become a significant issue in securing these environments to allow entities decide on the reliability and trustworthiness of other entities, besides it helps coping with defection problems and stimulating entities to cooperate. Recent models on evaluating trustworthiness in distributed systems have heavily focused on assessing trustworthiness of entities and isolate misbehaviours based on single trust metrics. Less effort has been put on the investigation of the subjective nature and differences in the way trustworthiness is perceived to produce a composite multidimensional trust metrics to overcome the limitation of considering single trust metric. In the light of this context, this thesis concerns the evaluation of entities’ trustworthiness by the design and investigation of trust metrics that are computed using multiple properties of trust and considering environment. Based on the concept of probabilistic theory of trust management technique, this thesis models trust systems and designs cooperation techniques to evaluate trustworthiness in mobile ad hoc networks (MANETs). A recommendation based trust model with multi-parameters filtering algorithm, and multidimensional metric based on social and QoS trust model are proposed to secure MANETs. Effectiveness of each of these models in evaluating trustworthiness and discovering misbehaving nodes prior to interactions, as well as their influence on the network performance has been investigated. The results of investigating both the trustworthiness evaluation and the network performance are promising.
25
Shabut, Antesar R. M. "Trust Computational Models for Mobile Ad Hoc Networks. Recommendation Based Trustworthiness Evaluation using Multidimensional Metrics to Secure Routing Protocol in Mobile Ad Hoc Networks". Thesis, University of Bradford, 2015. http://hdl.handle.net/10454/7501.
Abstract (sommario):
Distributed systems like e-commerce and e-market places, peer-to-peer networks, social networks, and mobile ad hoc networks require cooperation among the participating entities to guarantee the formation and sustained existence of network services. The reliability of interactions among anonymous entities is a significant issue in such environments. The distributed entities establish connections to interact with others, which may include selfish and misbehaving entities and result in bad experiences. Therefore, trustworthiness evaluation using trust management techniques has become a significant issue in securing these environments to allow entities decide on the reliability and trustworthiness of other entities, besides it helps coping with defection problems and stimulating entities to cooperate. Recent models on evaluating trustworthiness in distributed systems have heavily focused on assessing trustworthiness of entities and isolate misbehaviours based on single trust metrics. Less effort has been put on the investigation of the subjective nature and differences in the way trustworthiness is perceived to produce a composite multidimensional trust metrics to overcome the limitation of considering single trust metric. In the light of this context, this thesis concerns the evaluation of entities’ trustworthiness by the design and investigation of trust metrics that are computed using multiple properties of trust and considering environment.
Based on the concept of probabilistic theory of trust management technique, this thesis models trust systems and designs cooperation techniques to evaluate trustworthiness in mobile ad hoc networks (MANETs). A recommendation based trust model with multi-parameters filtering algorithm, and multidimensional metric based on social and QoS trust model are proposed to secure MANETs. Effectiveness of each of these models in evaluating trustworthiness and discovering misbehaving nodes prior to interactions, as well as their influence on the network performance has been investigated. The results of investigating both the trustworthiness evaluation and the network performance are promising.Ministry of Higher Education in Libya and the Libyan Cultural Attaché bureau in London
26
Johnson, Lauren. "A MULTIDIMENSIONAL APPROACH TO INTERORGANIZATIONAL COMMUNICATION VIA EMERGENCY MANAGEMENT ORGANIZATIONS AND THEIR TWITTER ACCOUNTS". UKnowledge, 2019. https://uknowledge.uky.edu/comm_etds/83.
Abstract (sommario):
Using an adaptation of O’Connor and Shumate’s (2018) theoretical propositions, this research examines interorganizational communication through the lens of multidimensional networks. Twitter data was crawled from a selection of emergency management organization accounts to measure affinity, representational, flow, and semantic networks. These data included the organizations’ followed accounts, retweets, replies, and mentions. A thematic analysis of the organizations’ mission statements was also conducted in order to inform the examination of the semantic networks. The results show a significant relationship between the number of accounts an organization follows and the likelihood of having its message shared. This research provides a further theoretical application of a network analysis method of studying interorganizational communication as well as a practical application for organizations seeking to increase their engagement on Twitter.
27
Svensson, Björn. "A Multidimensional Filtering Framework with Applications to Local Structure Analysis and Image Enhancement". Doctoral thesis, Linköpings universitet, Medicinsk informatik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11271.
Abstract (sommario):
Filtering is a fundamental operation in image science in general and in medical image science in particular. The most central applications are image enhancement, registration, segmentation and feature extraction. Even though these applications involve non-linear processing a majority of the methodologies available rely on initial estimates using linear filters. Linear filtering is a well established cornerstone of signal processing, which is reflected by the overwhelming amount of literature on finite impulse response filters and their design. Standard techniques for multidimensional filtering are computationally intense. This leads to either a long computation time or a performance loss caused by approximations made in order to increase the computational efficiency. This dissertation presents a framework for realization of efficient multidimensional filters. A weighted least squares design criterion ensures preservation of the performance and the two techniques called filter networks and sub-filter sequences significantly reduce the computational demand. A filter network is a realization of a set of filters, which are decomposed into a structure of sparse sub-filters each with a low number of coefficients. Sparsity is here a key property to reduce the number of floating point operations required for filtering. Also, the network structure is important for efficiency, since it determines how the sub-filters contribute to several output nodes, allowing reduction or elimination of redundant computations. Filter networks, which is the main contribution of this dissertation, has many potential applications. The primary target of the research presented here has been local structure analysis and image enhancement. A filter network realization for local structure analysis in 3D shows a computational gain, in terms of multiplications required, which can exceed a factor 70 compared to standard convolution. For comparison, this filter network requires approximately the same amount of multiplications per signal sample as a single 2D filter. These results are purely algorithmic and are not in conflict with the use of hardware acceleration techniques such as parallel processing or graphics processing units (GPU). To get a flavor of the computation time required, a prototype implementation which makes use of filter networks carries out image enhancement in 3D, involving the computation of 16 filter responses, at an approximate speed of 1MVoxel/s on a standard PC.
28
Liu, Quan. "Modélisation bayésienne des interactions multidimensionnelles dans un système complexe : application à la gestion des risques de crues". Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0038/document.
Abstract (sommario):
Le travail aborde la modélisation et l’analyse de systèmes complexes, caractérisés, dans un cadre incertain et évolutif, par de nombreuses interactions entre composants. Dans un cadre de gestion des risques, le travail vise à créer un modèle causal spatio-temporel pour l’explication et la probabilisation de certains événements redoutés à des fins de diagnostic et de pronostic. Le travail de modélisation est basé sur l’approche bayésienne et, plus particulièrement, sur les Réseaux Bayésiens (RB). Dans l’optique de considérer des systèmes de grande taille et de représenter leur complexité spatio-temporelle, leur caractère multiéchelles et incertain dans un cadre dynamique, l’idée de ce travail est alors d’étendre le concept des Réseaux Bayesiens Dynamiques (RBD) et d’utiliser le paradigme Orienté Objet pour l’appliquer aux réseaux bayésiens. Dans leur forme actuelle, les réseaux bayésiens orientés objet permettent de créer des instances réutilisables mais non instanciables. En d’autres termes, cela implique que l’objet généré est susceptible d’être appelé plusieurs fois dans la construction d’un modèle mais sans pour autant que ces paramètres (tables de probabilités marginales ou conditionnelles) ne soient modifiés. Ce travail de thèse vise à combler cette lacune en proposant une approche structurée permettant de construire des grands systèmes à base d’objets (caractérisés par des réseaux bayésiens simples) dont les paramètres peuvent être actualisés en fonction de l’instant ou du contexte de leur appel et de leur utilisation. Ce concept est concrétisé sous la forme de Réseaux Bayésiens Multidimensionnels par leur propension à combiner plusieurs dimensions qu’elles soient spatiales ou temporellesThe work addresses the modelling and analysis of complex systems, characterized, in an uncertain and evolving framework, by numerous interactions between components. Within a risk management framework, the work aims to create a spatio-temporal causal model for the explanation and probability of certain feared events for diagnostic and prognostic purposes. The modelling work is based on the Bayesian approach and, more specifically, on the Bayesian Networks (BN). In an attempt to consider large-scale systems and represent their spatio-temporal complexity, their multi-scale and uncertain character in a dynamic framework, the idea of this work is then to extend the concept of Dynamic Bayesian Networks (DBN) and use the Object Oriented paradigm to apply it to Bayesian networks. In their current form, object-oriented Bayesian networks can create reusable but not instantiable instances. In other words, this implies that the generated object is likely to be called several times in the construction of a model, but without these parameters (marginal or conditional probabilities tables) being modified. This thesis aims to fill this gap by proposing a structured approach to construct large object-based systems (characterized by simple Bayesian networks) whose parameters can be updated according to the moment or context of their call and use. This concept is embodied in the form of Bayesian Multidimensional Networks by their propensity to combine several dimensions, whether spatial or temporal
29
Wang, Shuo. "Joint Analysis of Social and Item Response Networks with Latent Space Models". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1571918340162685.
30
Koneru, Avanthi. "Comparative Study of RSS-Based Collaborative Localization Methods in Wireless Sensor Networks". Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5452/.
Abstract (sommario):
In this thesis two collaborative localization techniques are studied: multidimensional scaling (MDS) and maximum likelihood estimator (MLE). A synthesis of a new location estimation method through a serial integration of these two techniques, such that an estimate is first obtained using MDS and then MLE is employed to fine-tune the MDS solution, was the subject of this research using various simulation and experimental studies. In the simulations, important issues including the effects of sensor node density, reference node density and different deployment strategies of reference nodes were addressed. In the experimental study, the path loss model of indoor environments is developed by determining the environment-specific parameters from the experimental measurement data. Then, the empirical path loss model is employed in the analysis and simulation study of the performance of collaborative localization techniques.
31
Vicente, Paulo Nuno Gouveia. "International News Reporting in the Multidimensional Network: The socio-demographics, professional culture and newswork of foreign correspondents working across Sub-Saharan Africa". Doctoral thesis, Faculdade de Ciências Sociais e Humanas, Universidade Nova de Lisboa, 2013. http://hdl.handle.net/10362/10798.
Abstract (sommario):
Tese apresentada para cumprimento dos requisitos necessários à obtenção do grau de Doutor em Media DigitaisUma porção significativa do nosso conhecimento quotidiano sobre a África Subsaariana provém do trabalho dos repórteres internacionais. Contudo, e ainda que estes actores desempenhem um papel crítico na comunicação do Outro distante, frequentemente criticado pelos seus défices representacionais, a investigação académica sobre o trabalho dos correspondentes internacionais tem sido consideravelmente negligenciada: encontra-se desactualizada em décadas, carecendo de um exame sistemático das realidades efectivas do jornalismo em África e da evolução do trabalho de Pro-Ams e organizações de media dos cidadãos, suportados por meios digitais ligados em rede. Esta tese tem como objecto a caracterização e análise sociodemográfica destes indivíduos, das suas culturas profissionais e trabalho noticioso. Inspecciona trajectórias de longo curso no jornalismo internacional, combinando-as com desenvolvimentos de curto prazo baseados nas transformações na microelectrónica e digitalização. São delineadas três linhas de inquérito: quem está realmente a reportar em todo o continente, quais são as principais características das culturas ocupacionais e os constrangimentos que impendem sobre as rotinas de produção dos trabalhadores noticiosos. Avaliamos como estão os repórteres internacionais a reposicionar-se num ambiente comunicacional em transformação, como interpretam a sua própria ocupação e o papel dos actores emergentes na esfera mediática transnacional. Simultaneamente, contribuímos com uma investigação exploratória sobre as actividades das organizações de media dos cidadãos. Para cumprir estes objectivos, conduzimos o primeiro questionário online Pan-Africano de que há registo sobre o trabalho dos repórteres internacionais, recolhendo respostas de 124 participantes em 41 países. Estes resultados são complementados através de entrevistas semiestruturadas com 43 jornalistas profissionais, em Nairobi, Dakar e Joanesburgo. Os resultados obtidos desafiam a narrativa que apresenta a reportagem internacional como uma espécie em extinção. Ao invés, suportam uma visão diferenciada entre continuidades localizadas e rupturas localizadas na contemporânea e pós-industrial esfera mediática: a sua sociodemografia expressa uma nova economia da correspondência internacional caracterizada por uma considerável precariedade, particularmente no caso dos trabalhadores independentes (freelance), enquanto a utilização de media digitais ligados em rede conduz o campo a uma confederação de correspondências com múltiplas camadas. O campo não é já um território exclusivo de profissionais e estes têm agora de lidar com a escala sem precedentes de conteúdos gerados pelos utilizadores e reacções directas. Os profissionais despendem uma muito considerável porção de tempo diário na Internet, o que sugere uma mudança de paradigma nas práticas de recolha informativa e, em última análise, na sua cultura epistemológica.
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Rimec, Daniel. "Multidimensional Assessment For a Case Studied Zero Energy Building : Climate positive buildings with and without a connection to the district heating network". Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-54650.
Abstract (sommario):
The purpose of this report is to get an overview of the CO2 reduction possibilities when adopting different renewable energy source, when the case studied building sustains a district heating network connection and when not, and how the renewable energy source flexibilities (Solar and Wind) differ depending on region. The method regards a ETC house that falls into the climate positive category and assesses the reduction when comparing CO2 emissions form the energy demand. The result for the flexibilities is then compared to the BBR demand. The result shows a difference of around 10% in production for the flexibilities when comparing the northern and middle region with the southern. And a decrease between 19-36% gCO2. Comparing a scenario with and without a connection to the district heating network showed that when the ground source heat pump offsets the energy demand, CO2, and cost reductions (6 and 4% respectively) can be seen. With an average installation cost, the payback period for the ground source heat pump can be estimated to be around 4 year. In conclusion the thesis project shows that the climate is a ruling factor when assessing energy questions for the residential sector. It also shows the difference in CO2 and cost that comes with it can be reduced and help mitigated the sectors effects on the environment. This in turn shows that the overall reduction of CO2 for the case studied building follows the demands and goals set by the European commission and gives motivation to expand the construction as cost is also reduced.
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Verbylaitė, Laura. "Atgalinio klaidos sklidimo neuroninio tinklo realizavimo problemos ir taikymai". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080924_175458-27006.
Abstract (sommario):
Šiame magistriniame darbe išanalizuota dirbtinių neuroninių tinklų teorija. Detaliai išnagrinėtas atgalinio klaidos sklidimo algoritmas. Pagal jį parašytos programos: C++ kalba ir Matlab sistemoje su siūlomais neuroninių tinklų konstravimo įrankiais. Lyginant programas atlikti tyrimai su irisų ir vyno atpažinimo duomenimis. Tyrimo metu ištirti ir paanalizuoti daugiasluoksniai neuroniniai tinklai su paslėptais vienu ir dviem sluoksniais.This paper offers a profound research the theory of artificial neural network. It gives a deep analysis of error back propagation and provides error back propagation program written in C++ language and Matlab system with relevant neural network construction tools. To compare both programs I carried out research of wines recognition data and irises data. Analyzed feedforward neural network with hidden one and two layers.
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Gorana, Rakić Bajić. "Psihološko blagostanje: provera realnostikonstrukta u okviru multidimenzionog modela Carol Ryff". Phd thesis, Univerzitet u Novom Sadu, Filozofski fakultet u Novom Sadu, 2016. http://www.cris.uns.ac.rs/record.jsf?recordId=100356&source=NDLTD&language=en.
Abstract (sommario):
Osnovni cilj prikazanog istraživanja je bilo unapredivanje postojecih znanja opsihološkom blagostanju putem ispitivanja multidimenzionalnosti konstrukta injegovih korelata. Proveravana je struktura multidimenizonog modela Caroll Ryffprema kome psihološko blagostanje obuhvata šest dimenzija: Samoprihvatanje, Svrhaživota, Licni rast, Ovladavanje okruženjem, Autonomija i Pozitivni odnosi sadrugima, te relacije tih dimenzija sa pretpostavljenim prediktorima i konsekventima.U istraživanju je ucestvovalo 657 odraslih osoba (41,9% muškog i 58,1%ženskog pola) sa teritorije Srbije, uzrasta od 18 do 89 godina. Korišceni su sledeciinstrumenti: Upitnik o demografskim karakteristikama konstruisan za potrebeistraživanja, Skale psihološkog blagostanja, Skala zadovoljstva životom, Skalapozitivnog i negativnog afektiviteta (PANAS), Upitnik za procenjivanje partnerskeafektivne vezanosti, Bekov inventar anksioznosti, Skala samostišavanja, Skalaoptimizma – pesimizma i Skala depresivne licnosti.Rezultati sprovedenih analiza nisu potvrdili šestodimenzionalnost modela, aliukazuju na multidimenzionalnost psihološkog blagostanja, te je predložentrodimenzioni model. Dalja ispitivanja korelata psihološkog blagostanja sprovedenana ekstrahovanom trofaktorskom modelu su pokazala da je psihološko blagostanjeznacajan prediktor subjektivnog blagostanja, anksioznosti i subjektivnih procenafizickog zdravlja i materijalne situacije, dok su optimizam, pesimizam, depresivnalicnost i uzrast znacajni prediktori psihološkog blagostanja.The main goal of the presented study was to extend the existing knowledge on thepsychological well-being though testing psychological well-beingmultidimensionality and relationship with its correlates. The six-dimension Carol Ryffmodel of the psychological well-being was used, which consists of the followingdimensions: Self-acceptance, Personal growth, Environmental mastery, Autonomy,Purpose in life and Positive relations with others. Also included was a relationshipbetween psychological well-being and assumed predictors and consequences.The research included 657 adults, aged between 18 to 89 years, from Serbia.The following instruments were used: a questionnaire on socio-demographiccharacteristics, Scales of Psychological Well-Being, Satisfaction with life scale, Thepositive and negative affect schedule – PANAS, Experience of Close RelationshipsScale, Beck Anxiety Inventory, the self-silencing scale, Optimism – pessimism scaleand Depressive personality scale.The results did not confirm the six-dimension model theory, but did indicate amultidimensional structure of the psychological well-being. The three factor solutionwas extracted, so the rest of study was conducted with three dimensionalpsychological model. Analysis showed that psychological well-being is a significantpredictor of subjective well-being, anxiety and subjective assessment of physicalhealth and material state. The optimism, pessimism, depressive personality and ageare the significant predictors of psychological well-being.
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Ringienė, Laura. "Hibridinis neuroninis tinklas daugiamačiams duomenims vizualizuoti". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140912_140105-52586.
Abstract (sommario):
Šio darbo tyrimų sritis yra duomenų tyryba remiantis daugiamačių duomenų vizualia analize. Tai leidžia tyrėjui betarpiškai dalyvauti duomenų analizės procese, geriau pažinti sudėtingus duomenis ir priimti geriausius sprendimus. Disertacijos tikslas yra sukurti metodą tokios duomenų projekcijos radimui plokštumoje, kad tyrėjas galėtų pamatyti ir įvertinti daugiamačių taškų tarpgrupinius panašumus/skirtingumus. Šiam tikslui pasiekti yra pasiūlytas radialinių bazinių funkcijų ir daugiasluoksnio perceptrono, turinčio ,,butelio kaklelio“ neuroninio tinklo savybes, junginys. Naujas tinklas naudojamas vizualiai daugiamačių duomenų analizei, kai atidėjimui plokštumoje arba trimatėje erdvėje taškai gaunami paskutinio paslėpto neuronų sluoksnio išėjimuose, kai į tinklo įėjimą paduodami daugiamačiai duomenys. Šio tinklo ypatybė yra ta, kad gautas vaizdas plokštumoje labiau atspindi bendrą duomenų struktūrą (klasteriai, klasterių tarpusavio artumas, taškų tarpklasterinis panašumas) nei daugiamačių taškų tarpusavio išsidėstymą.The area of research is data mining based on multidimensional data visual analysis. This allows researcher to participate in the process of data analysis directly, to understand the complex data better and to make the best decisions. The objective of the dissertation is to create a method for making a multidimensional data projection on the plane such that the researcher could see and assess the intergroup similarities and differences of multidimensional points. In order to achieve the target, a new hybrid neural network is proposed and investigated. This neural network integrates the ideas both of the radial basis function neural network and that of a multilayer perceptron, which has the properties of a ''bottleneck'' neural network. The new network is used for the visual analysis of multidimensional data in such a way that the output values of the neurons of the last hidden layer are the two-dimensional or three-dimensional projections of the multidimensional data, when the multidimensional data is given to the network. A peculiarity of the network is that the visualization results on the plane reflect the general structure of the data (clusters, proximity between clusters, intergroup similarities of points) rather than the location of multidimensional points.
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Seneviratne, Vishwa. "Design and Rapid-prototyping of Multidimensional-DSP Beamformers Using the ROACH-2 FPGA Platform". University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1488149940846702.
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Amaral, Carlos Eduardo Menezes. "Rede de atenÃÃo em saÃde mental no municÃpio de Fortaleza: uma anÃlise multidimensional na perspectiva de profissionais de diferentes dispositivos". Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10552.
Abstract (sommario):
Este trabalho buscou compreender a rede de saÃde mental do municÃpio de Fortaleza a partir da perspectiva de trabalhadores de diferentes dispositivos, utilizando um enfoque hermenÃutico qualitativo. Desenvolvemos para a pesquisa um modelo analÃtico-conceitual de rede, com cinco dimensÃes constitutivas: 1) unidades mÃnimas; 2) conectividade; 3) integraÃÃo; 4) normatividades; e 5) subjetividade. A pesquisa foi realizada em trÃs serviÃos de saÃde (CSF, CAPS e Hospital PsiquiÃtrico - HSMM), onde foram realizadas observaÃÃo livre e 21 entrevistas semi-estruturadas com profissionais de cada dispositivo. Como resultados, demarcamos as diferentes propostas de cuidado de cada serviÃo, seus fluxos internos de atividades, assim como os critÃrios de entrada, saÃda e encaminhamento de cada instituiÃÃo. As relaÃÃes entre os serviÃos abrangeram seis modalidades: encaminhamentos, contrarreferÃncia, contato telefÃnico, reuniÃo de gestores, busca ativa e apoio matricial. Mapeamos tambÃm relaÃÃes com outros serviÃos de saÃde, assim como espaÃos de outros setores, acrescentando nesses casos o âuso de espaÃoâ e âparceriaâ como novas modalidades de relaÃÃo. Os profissionais defendem a existÃncia de complementaridade entre os serviÃos de saÃde pesquisados, ainda que o CAPS argumente pelo carÃter transitÃrio e inadequado dessa relaÃÃo, e o HSMM por sua estabilidade e pertinÃncia. TambÃm foi defendida a complementaridade em relaÃÃo Ãs intervenÃÃes de promoÃÃo da saÃde, prevenÃÃo de agravos e recuperaÃÃo da saÃde, ainda que sà tenham sido citadas pelos entrevistados a realizaÃÃo de aÃÃes de prevenÃÃo secundÃria e recuperaÃÃo. TambÃm identificamos uma incongruÃncia entre o objeto de intervenÃÃo definido pelo CAPS, que o entende como um amplo conjunto de necessidades sociais e de saÃde das pessoas com sofrimento psÃquico/transtorno mental, e o objeto delimitado no HSMM, que o recorta como o transtorno mental e a situaÃÃo de crise. Destacamos ainda, como parte da dimensÃo de subjetividade, as formas de relaÃÃo com os usuÃrios no CSF, CAPS e HSMM, assim como o protagonismo polÃtico em relaÃÃo à reforma psiquiÃtrica dos profissionais do CAPS. Em conclusÃo, argumentamos que nosso modelo analÃtico-conceitual permitiu evidenciar vÃrios aspectos sutis da rede de atenÃÃo em saÃde mental de Fortaleza, possibilitando ampliar a compreensÃo da rede.This work aimed to comprehend the mental health care network in the city of Fortaleza, from the perspective of workers from different services, using aqualitative hermeneutic approach. We developed conceptual-analytical model for networks, with five dimensions: 1) minimum units; 2) connectivity; 3) integration; 4) normativities; 5) subjectivity. The research included three health services: a primary care center (CSF), a psychosocial care center (CAPS) and a psychiatric hospital (HSMM), in which we performed free observation and 21 semi-structured interviews with professionals. As results, we found different concepts of care in each service, as well as diverse internal activities flows, and entrance, discharge and referral criteria. The connections between services included six varieties: referrals, counter-reference, phone contact, manager meeting, active search and matrix support. We also mapped the interaction with other health services, and services outside the health sector, cases in which we discovered âuse of spaceâ and âpartnershipâ as new types of connections. Also, the workers support the complementarity between the services researched, although CAPS argues for the transient nature of such relation, while HSMM believes in its permanence. The complementarity between prevention, health promotion and health recovery was also supported, although only secondary prevention and health recovery actions were identified by the workers. We also found incongruence between CAPSâs âintervention objectâ, defined by a broad specter of health and social needs of people with mental disorders/psychic suffering, and HSMMâs definition, limited to crisis and mental disorders itself. Furthermore, we stress as part of the subjectivity dimension the types of patient rapport developed in each service, as well as the political action toward the Psychiatric Reform from CAPSÂs professionals. We conclude that our conceptual-analytical model allowed us to indicate several subtle aspects of the mental health care network of the city of Fortaleza, widening the comprehension of such network.
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Tillemans, Stephen. "Development of an instrument for data collection in a multidimensional scaling study of personal Web usage in the South African workplace". Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/21646.
Abstract (sommario):
Thesis (MBA)--Stellenbosch University, 2011.In a relatively very short period the Internet has grown from being virtually unknown to becoming an essential business tool. Together with its many benefits, the Internet has unfortunately brought with it several new organisational challenges. One of these challenges is how to manage personal Web usage (PWU) in the workplace effectively. Although many managers see PWU as a form of workplace deviance, many researchers have pointed out its potential benefits such as learning, time-saving, employee well-being and a source of ideas. To help organisations manage PWU in the workplace more effectively, this research realised the need for a typology of PWU behaviours in the South African workplace. Multidimensional scaling (MDS) was identified as an objective method of creating such a typology. The objective of this research was therefore to develop an instrument to gather data for a multidimensional scaling study of PWU behaviours in the South African workplace. A questionnaire was designed that consists of three distinct sections. The first section contains seven pre-coded demographics questions that correspond with specific demographic variables, proven to have a relationship with PWU. The second section of the questionnaire is designed to gather dissimilarity data for input into an MDS algorithm. To begin with, 25 Web usage behaviours of South Africans were identified using Google Ad Planner. After weighing up various options of comparing the Web usage behaviours, the pairwise comparison method was selected. Ross sequencing was used to reduce positioning and timing effects. To reduce the number of judgements per participant, the 300 required judgments are split six ways, resulting in 50 judgements per participant. The last section of the questionnaire is designed to gather data to assist with interpreting the dimensions of the MDS configuration. Eight benefits and risks of PWU were identified. These are combined into a matrix together with the 25 Web usage behaviours. The data from this section will allow future research to use linear regression to discover the relationship between the Web usage behaviours (the objects), and the benefits and risks of PWU (the variables). It is believed that this design offers a fair compromise between the time and effort required of participants and the quality and integrity of the acquired data.
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Medvedev, Viktor. "Tiesioginio sklidimo neuroninių tinklų taikymo daugiamačiams duomenims vizualizuoti tyrimai". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080204_162347-54385.
Abstract (sommario):
Disertacijos tyrimų sritis yra daugiamačių duomenų analizė, bei tų duomenų suvokimo gerinimo būdai. Duomenų suvokimas yra sudėtingas uždavinys, ypač kai duomenys nurodo sudėtingą objektą, kuris aprašytas daugeliu parametrų. Disertacijoje nagrinėjami dirbtinių neuroninių tinklų algoritmai daugiamačiams duomenims vizualizuoti. Darbo tyrimų objektas yra dirbtiniai neuroniniai tinklai, skirti daugiamačių duomenų vizualizavimui. Su šiuo objektu yra betarpiškai susiję dalykai: daugiamačių duomenų vizualizavimas; dimensijos mažinimo algoritmai; projekcijos paklaidos; naujų taškų atvaizdavimas; vizualizavimui skirto neuroninio tinklo permokymo strategijos ir parametrų optimizavimas; lygiagretieji skaičiavimai. Pagrindinis disertacijos tikslas yra sukurti ir tobulinti metodus, kuriuos taikant būtų efektyviai minimizuojamos daugiamačių duomenų projekcijos paklaidos naudojantis dirbtiniais neuroniniais tinklais bei projekcijos algoritmais. Darbe atliktų tyrimų rezultatai atskleidė naujas medicininių (fiziologinių) duomenų analizės galimybes.The research area of this work is the analysis of multidimensional data and the ways of improving apprehension of the data. Data apprehension is rather a complicated problem especially if the data refer to a complex object or phenomenon described by many parameters. The research object of the dissertation is artificial neural networks for multidimensional data projection. General topics that are related with this object: multidimensional data visualization; dimensionality reduction algorithms; errors of projecting data; the projection of the new data; strategies for retraining the neural network that visualizes multidimensional data; optimization of control parameters of the neural network for multidimensional data projection; parallel computing. The key aim of the work is to develop and improve methods how to efficiently minimize visualization errors of multidimensional data by using artificial neural networks. The results of the research are applied in solving some problems in practice. Human physiological data that describe the human functional state have been investigated.
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Sun, Wen. "A study of interacting stochastic networks : large scale, long time behavior and fluctuations, with applications in communication networks and protein polymerization". Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS075.
Abstract (sommario):
Ce document est consacré aux analyses de grands réseaux stochastiques utilisés pour étudier des réseaux de communication et ainsi que certains phénomènes biologiques. La première partie se compose de trois modèles pour évaluer l’efficacité des algorithmes de duplication et de placement dans les grands systèmes distribués. Au chapitre 2, la dynamique du système est décrite l’aide de la mesure empirique associée à un processus de transient multidimensionnel. Une étude détaillée de ces processus est effectuée sur plusieurs échelles de temps rapides. Des principes de moyenne stochastique avec plusieurs échelles de temps sont étudiées. Aux chapitres 3 et 4, les interactions considérées peuvent avoir des tailles de saut illimitées et se produire dans un ensemble aléatoire fini de nœuds. Le processus de la mesure empirique associé n’ayant pas d’équations d’évolution simples, nous développons une analyse de champ moyen spécifique pour étudier ces systèmes. Le comportement en temps long des processus de diffusions non linéaires correspondants est aussi analysé. La deuxième partie présente deux modèles pour étudier la variabilité dans les modèles de polymérisation. Dans le chapitre 5, nous étudions les processus de polymérisation et de fragmentation avec l’hypothèse d’un noyau critique pour la taille des polymères. Notre résultat montre que ces modèles semblent donner une explication raisonnable de la transition de phase courte du phénomène de polymérisation, et surtout de la grande variabilité de l’instant de transition, qui ont été observés dans de nombreuses expériences. Au chapitre 6, nous proposons un théorème de limite centrale fonctionnelle dans le modèle de Becker-DöringThis PhD document is devoted to the analyses of large stochastic networks used to study mathematical models in communication networks and in biology. The first part consists of the analysis of three models used to evaluate the efficiency of duplication and placement algorithms in large distributed systems. These models are represented by large stochastic networks under different scaling regimes assumptions. In Chapter 2, the dynamic of the system can be described with the empirical measure associated to a multi-dimensional transient Markov process. We provide a detailed study of these processes on several fast time scales. Stochastic averaging principles with multiple time scales are investigated in particular. In Chapter 3 and Chapter 4, the interactions have unbounded jump sizes and occur within a limited random set of nodes. We develop a convenient mean field analysis in despite that the associated empirical measures do not have autonomous evolution equations. We also study the long time behavior of the corresponding limiting nonlinear jump diffusions. The second part analyzes two models used to study the variability in the polymerization phenomena occurring in a biological context. In Chapter 5, we investigate the polymerization and fragmentation processes with an assumption of critical nucleus size. A scaling analysis of these stochastic models show that the sharp phase transition and, especially the large variance, observed in the experiments can be explained by these models. In Chapter 6, we provide a functional central limit theorem in the classical (infinite dimensional) stochastic Becker-Döring model
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PECCI, ANGELO. "Geoinformatic methodologies and quantitative tools for detecting hotspots and for multicriteria ranking and prioritization: application on biodiversity monitoring and conservation". Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1341.
Abstract (sommario):
Chi ha la responsabilità di gestire un’area protetta non solo deve essere consapevole dei problemi ambientali dell’area ma dovrebbe anche avere a disposizione dati aggiornati e appropriati strumenti metodologici per esaminare accuratamente ogni singolo problema. In effetti, il decisore ambientale deve organizzare in anticipo le fasi necessarie a fronteggiare le prevedibili variazioni che subirà la pressione antropica sulle aree protette.
L’obiettivo principale della Tesi è di natura metodologica e riguarda il confronto tra differenti metodi statistici multivariati utili per l’individuazione di punti critici nello spazio e per l’ordinamento degli “oggetti ambientali” di studio e quindi per l’individuazione delle priorità di intervento ambientale.
L’obiettivo ambientale generale è la conservazione del patrimonio di biodiversità. L’individuazione, tramite strumenti statistici multivariati, degli habitat aventi priorità ecologica è solamente il primo fondamentale passo per raggiungere tale obiettivo. L’informazione ecologica, integrata nel contesto antropico, è un successivo essenziale passo per effettuare valutazioni ambientali e per pianificare correttamente le azioni volte alla conservazione.
Un’ampia serie di dati ed informazioni è stata necessaria per raggiungere questi obiettivi di gestione ambientale. I dati ecologici sono forniti dal Ministero dell’Ambiente Italiano e provengono al Progetto “Carta della Natura” del Paese. I dati demografici sono invece forniti dall’Istituto Italiano di Statistica (ISTAT). I dati si riferiscono a due aree geografiche italiane: la Val Baganza (Parma) e l’Oltrepò Pavese e Appennino Ligure-Emiliano.
L’analisi è stata condotta a due differenti livelli spaziali: ecologico-naturalistico (l’habitat) e amministrativo (il Comune). Corrispondentemente, i risultati più significativi ottenuti sono:
1. Livello habitat: il confronto tra due metodi di ordinamento e determinazione delle priorità, il metodo del Vettore Ideale e quello della Preminenza, tramite l’utilizzo di importanti metriche ecologiche come il Valore Ecologico (E.V.) e la Sensibilità Ecologica (E.S.), fornisce dei risultati non direttamente comparabili. Il Vettore Ideale, non essendo un procedimento basato sulla ranghizzazione dei valori originali, sembra essere preferibile nel caso di paesaggi molto eterogenei in senso spaziale. Invece, il metodo della Preminenza probabilmente è da preferire in paesaggi ecologici aventi un basso grado di eterogeneità intesa nel senso di differenze non troppo grandi nel E.V. ed E.S. degli habitat.
2. Livello comunale: Al fine di prendere delle decisioni gestionali ed essendo gli habitat solo delle suddivisioni naturalistiche di un dato territorio, è necessario spostare l’attenzione sulle corrispondenti unità amministrative territoriali (i Comuni). Da questo punto di vista, l’introduzione della demografia risulta essere un elemento centrale oltre che di novità nelle analisi ecologico-ambientali. In effetti, l’analisi demografica rende il risultato di cui al punto 1 molto più realistico introducendo altre dimensioni (la pressione antropica attuale e le sue tendenze) che permettono l’individuazione di aree ecologicamente fragili. Inoltre, tale approccio individua chiaramente le responsabilità ambientali di ogni singolo ente territoriale nei riguardi della difesa della biodiversità. In effetti un ordinamento dei Comuni sulla base delle caratteristiche ambientali e demografiche, chiarisce le responsabilità gestionali di ognuno di essi.
Un’applicazione concreta di questa necessaria quanto utile integrazione di dati ecologici e demografici viene discussa progettando una Rete Ecologica (E.N.). La Rete cosi ottenuta infatti presenta come elemento di novità il fatto di non essere “statica” bensì “dinamica” nel senso che la sua pianificazione tiene in considerazione il trend di pressione antropica al fine di individuare i probabili punti di futura fragilità e quindi di più critica gestione.Who has the responsibility to manage a conservation zone, not only must be aware of environmental problems but should have at his disposal updated databases and appropriate methodological instruments to examine carefully each individual case. In effect he has to arrange, in advance, the necessary steps to withstand the foreseeable variations in the trends of human pressure on conservation zones. The essential objective of this Thesis is methodological that is to compare different multivariate statistical methods useful for environmental hotspot detection and for environmental prioritization and ranking. The general environmental goal is the conservation of the biodiversity patrimony. The individuation, through multidimensional statistical tools, of habitats having top ecological priority, is only the first basic step to accomplish this aim. Ecological information integrated in the human context is an essential further step to make environmental evaluations and to plan correct conservation actions. A wide series of data and information has been necessary to accomplish environmental management tasks. Ecological data are provided by the Italian Ministry of the Environment and they refer to the Map of Italian Nature Project database. The demographic data derives from the Italian Institute of Statistics (ISTAT). The data utilized regards two Italian areas: Baganza Valley and Oltrepò Pavese and Ligurian-Emilian Apennine. The analysis has been carried out at two different spatial/scale levels: ecological-naturalistic (habitat level) and administrative (Commune level). Correspondingly, the main obtained results are: 1. Habitat level: comparing two ranking and prioritization methods, Ideal Vector and Salience, through important ecological metrics like Ecological Value (E.V.) and Ecological Sensitivity (E.S.), gives results not directly comparable. Being not based on a ranking process, Ideal Vector method seems to be used preferentially in landscapes characterized by high spatial heterogeneity. On the contrary, Salience method is probably to be preferred in ecological landscapes characterized by a low degree of heterogeneity in terms of not large differences concerning habitat E.V. and E.S.. 2. Commune level: Being habitat only a naturalistic partition of a given territory, it is necessary, for management decisions, to move towards the corresponding administrative units (Communes). From this point of view, the introduction of demography is an essential element of novelty in environmental analysis. In effect, demographic analysis makes the goal at point 1 more realistic introducing other dimensions (actual human pressure and its trend) which allows the individuation of environmentally fragile areas. Furthermore this approach individuates clearly the environmental responsibility of each administrative body for what concerns the biodiversity conservation. In effect communes’ ranking, according to environmental/demographic features, clarify the responsibilities of each administrative body. A concrete application of this necessary and useful integration of ecological and demographic data has been developed in designing an Ecological Network (E.N.).The obtained E.N. has the novelty to be not “static” but “dynamic” that is the network planning take into account the demographic pressure trends in the individuation of the probable future fragile points.
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Voillet, Valentin. "Approche intégrative du développement musculaire afin de décrire le processus de maturation en lien avec la survie néonatale". Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0067/document.
Abstract (sommario):
Depuis plusieurs années, des projets d'intégration de données omiques se sont développés, notamment avec objectif de participer à la description fine de caractères complexes d'intérêt socio-économique. Dans ce contexte, l'objectif de cette thèse est de combiner différentes données omiques hétérogènes afin de mieux décrire et comprendre le dernier tiers de gestation chez le porc, période influençant la mortinatalité porcine. Durant cette thèse, nous avons identifié les bases moléculaires et cellulaires sous-jacentes de la fin de gestation, en particulier au niveau du muscle squelettique. Ce tissu est en effet déterminant à la naissance car impliqué dans l'efficacité de plusieurs fonctions physiologiques comme la thermorégulation et la capacité à se déplacer. Au niveau du plan expérimental, les tissus analysés proviennent de foetus prélevés à 90 et 110 jours de gestation (naissance à 114 jours), issus de deux lignées extrêmes pour la mortalité à la naissance, Large White et Meishan, et des deux croisements réciproques. Au travers l'application de plusieurs études statistiques et computationnelles (analyses multidimensionnelles, inférence de réseaux, clustering et intégration de données), nous avons montré l'existence de mécanismes biologiques régulant la maturité musculaire chez les porcelets, mais également chez d'autres espèces d'intérêt agronomique (bovin et mouton). Quelques gènes et protéines ont été identifiées comme étant fortement liées à la mise en place du métabolisme énergétique musculaire durant le dernier tiers de gestation. Les porcelets ayant une immaturité du métabolisme musculaire seraient sujets à un plus fort risque de mortalité à la naissance. Un second volet de cette thèse concerne l'imputation de données manquantes (tout un groupe de variables pour un individu) dans les méthodes d'analyses multidimensionnelles, comme l'analyse factorielle multiple (AFM) (ou multiple factor analysis (MFA)). Dans notre contexte, l'AFM fut particulièrement intéressante pour l'intégration de données d'un ensemble d'individus sur différents tissus (deux ou plus). Afin de conserver ces individus manquants pour tout un groupe de variables, nous avons développé une méthode, appelée MI-MFA (multiple imputation - MFA), permettant l'estimation des composantes de l'AFM pour ces individus manquantsOver the last decades, some omics data integration studies have been developed to participate in the detailed description of complex traits with socio-economic interests. In this context, the aim of the thesis is to combine different heterogeneous omics data to better describe and understand the last third of gestation in pigs, period influencing the piglet mortality at birth. In the thesis, we better defined the molecular and cellular basis underlying the end of gestation, with a focus on the skeletal muscle. This tissue is specially involved in the efficiency of several physiological functions, such as thermoregulation and motor functions. According to the experimental design, tissues were collected at two days of gestation (90 or 110 days of gestation) from four fetal genotypes. These genotypes consisted in two extreme breeds for mortality at birth (Meishan and Large White) and two reciprocal crosses. Through statistical and computational analyses (descriptive analyses, network inference, clustering and biological data integration), we highlighted some biological mechanisms regulating the maturation process in pigs, but also in other livestock species (cattle and sheep). Some genes and proteins were identified as being highly involved in the muscle energy metabolism. Piglets with a muscular metabolism immaturity would be associated with a higher risk of mortality at birth. A second aspect of the thesis was the imputation of missing individual row values in the multidimensional statistical method framework, such as the multiple factor analysis (MFA). In our context, MFA was particularly interesting in integrating data coming from the same individuals on different tissues (two or more). To avoid missing individual row values, we developed a method, called MI-MFA (multiple imputation - MFA), allowing the estimation of the MFA components for these missing individuals
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Ganzert, Christian Carvalho. "Desenvolvimento Sistêmico, equidade e interdependência: a busca por um modelo conceitual de gestão do equilíbrio das relações entre agentes econômicos regionais". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/96/96132/tde-21122012-102824/.
Abstract (sommario):
A busca por um modelo conceitual de gestão do equilíbrio em arranjos produtivos é inicialmente justificada pela ausência de metodologias realmente alinhadas aos preceitos sistêmicos de compreensão da realidade. A pesquisa visou à obtenção de um modelo conceitual de análise que indicasse as características que denotariam o equilíbrio entre agentes e manutenção da estrutura de relações de um determinado arranjo econômico de qualquer ordem. Para tal, utilizou-se de recursos da Social Network Analysis e da Teoria dos Jogos, orientados sob uma supra-metodologia de pesquisa derivada da SSM. O resultado final foi a obtenção de um modelo conceitual de gestão do equilíbrio entre agentes econômicos de escopo regional, baseado na análise das características de equilíbrio entre agentes e comportamento da estrutura de relações de um determinado arranjo econômico de qualquer ordem, pautando-se pela obtenção das medidas de relevância interna ponderadas, sendo o indicador de centralidade ponderada de betweenness utilizado para isso, e medidas que indicam o nível de estabilidade dos relacionamentos que compõem a estrutura da rede. Entretanto, para considerar esse modelo realmente aderente às premissas do pensamento sistêmico, foi necessário abstrair que as redes são formadas por múltiplas camadas de relacionamentos de várias naturezas, ou seja, são redes multidimensionais. Para tal, foi necessária a adaptação do ferramental de aferição dos indicadores descritos para a realidade de convergência de múltiplas redes. Nesse intento, foi preciso considerar que cada agente integrante possui pontos de vista diferenciados, ainda que isso possa ser relativizado para efeitos de simulação. Por fim, alinharam-se os indicadores de desvio de relevância interna e estabilidade de rede multidimensional para uma condição que expressasse, em termos relativos a quadrantes, cada uma das típicas possibilidades situacionais da rede, nesta tese enunciada como Classificação Conceitual de Estado de Rede Multidimensional.The search for a conceptual model of the regional economic agents\' relationships balance management is initially justified by the lack of methodologies that are really aligned to the Systems Thinking premises to comprehend the reality. The research aimed to obtaining a conceptual model that could indicate the characteristics which enable the understanding of the equilibrium between agents and maintenance of the relationships structure for a determined economic arrangement of any order. For that, it were used tools derived from the Social Networks Analysis and the Games Theory, oriented by a derivation of the Soft Systems Methodology as a supra methodology of research. The final result was the creation of a conceptual model which enables the management of the economic agents\' balance in a given economic network, reaching the objective of the research. It was possible by obtaining weighted measures of relevance, considering the betweenness of weighted centrality, and measures that indicate the level of stability of the relationships that make up the network structure. It was also necessary to abstract networks that are formed by multiple layers of varied natures\' relationships seeking to make this model really adhering to the assumptions of systemic thinking. It was equally necessary to adapt the tools for measuring the indicators described for the reality of the converged multiple networks. Finally, this dissertation enunciates the Conceptual Classification of the Multidimensional Networks Status.
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Bergier, Jean-Yves. "Analyse et modélisation du processus de propagation des effets des actions militaires d'influence au sein d'une population cible : approche par la culture et les réseaux sociaux". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0752/document.
Abstract (sommario):
L’étude de la conflictualité armée dans les pays en développement et des effets des interventions extérieures visant à la circonscrire constitue un enjeu majeur et multidisciplinaire. La complexité des processus sociaux entrelacés dans de tels contextes génère des défis particuliers pour les approches de modélisation et simulation informatique. En effet la forme des conflits actuels, centrés autour des populations locales, a amené les forces de stabilisation à développer des actions dites d'influence, qui se donnent pour but de convaincre les locaux de la légitimité des opérations. Ce travail en retient trois (opérations psychologiques OMI/PSYOPS, opérations civilo-militaires et Key Leader Engagements) et propose une modélisation permettant de représenter la propagation de leurs effets au sein d'une population virtuelle réaliste. Cela nécessite une représentation détaillée des mécanismes psychologiques de persuasion et d’influence et des structures sociales considérées, et constitue donc un apport à l’analyse des processus de communication au sein de réseaux sociaux. On fait le choix d'une simulation sociale orientée agents permettant de représenter d'une part un échantillon composé uniquement d'individus (jusqu’à environ 10 000) dotés de mécanismes de traitement réalistes, et d'autre part la complexité des sphères de sociabilité collective en générant cette population sous forme d'un réseau multicouche. Le modèle conceptuel ainsi conçu permet d’intégrer pour chaque étape des critères pertinents pour la simulation des actions, mais aussi, eut égard à la nature même de celles-ci et de leurs enjeux, d’éclairer certains mécanismes sociaux caractéristiques d’un conflit arméThe study, analysis and understanding of armed violence phenomenons in developing countries and of the effects of international military interventions aimed at resolving them is a crucial contemporary issue. These situations coincidentally present, considering the plethora and complexity of the implicated and intertwined social processes, a challenge for social computing, modeling and simulation. A challenge but also an opportunity, as the evolution of the forms of conflict, today centered on the local populations, has prompted the armies tasked with implementing stabilization missions to develop influence actions. Such operations, overall concerned with persuading the locals of the legitimacy of the operations, allow a more comprehensive approach to conflict resolution, beyond the simple use of force. Modeling some of these specific actions (PSYOPS, CIMIC, and Key Leader Engagement) is a credible project and a contribution to analysis of communication and persuasion processes in social networks by taking into account detailed and specific social and cultural factors. This research thus presents a conceptual model allowing simulation of the effects of these specific actions of influence in a realistic civilian population. We chose an agent-based approach as these lend particularly well with this type of research, allowing us to generate a group of up to 10,000 agents, composed solely of individuals for a detailed cognitive treatment, and structured as a multilayer network for representing complex sociality. Given the nature of such actions and their context of application, such a model also highlights some social mechanisms typical of armed conflict situations
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D'ANGELO, SILVIA. "Latent space models for multidimensional network data". Doctoral thesis, 2019. http://hdl.handle.net/11573/1255137.
Abstract (sommario):
Network data are any relational data recorded among a group of individuals, the nodes. When multiple relations are recorded among the same set of nodes, a more complex object arises, which we refer to as “multidimensional network”, or
“multiplex”, where different relations corresponding to different networks. In the past, statistical analysis of networks has mainly focused on single-relation network data, referring to a single relation of interest. Only in recent years statistical
models specifically tailored for multiplex data begun to be developed. In this context, only a few works have been introduced in the literature with the aim at extending the latent space modeling framework to multiplex data. Such framework postulates
that nodes may be characterized by latent positions in a p-dimensional Euclidean space and that the presence/absence of an edge between any two nodes depends on such positions. When considering multidimensional network data, latent space
models can help capture the associations between the nodes and summarize the observed structure in the different networks composing a multiplex. This dissertation discusses some latent space models for multidimensional network
data, to account for different features that observed multiplex data may present. A first proposal allows to jointly represent the different networks into a single latent space, so that average similarities between the nodes may be captured as
proximities in such space. A second work introduces a class of latent space models with node-specific effects, in order to deal with different degrees of heterogeneity within and between networks in multiplex data, corresponding to different types
of node-specific behaviours. A third work addresses the issue of clustering of the nodes in the latent space, a frequently observed feature in many real world network and multidimensional network data. Here, clusters of nodes in the latent space
correspond to communities of nodes in the multiplex. The proposed models are illustrated both via simulation studies and real world applications, to study their perfomances and abilities.
46
Hsiu-Chin, Chen. "SONMAS: A Structured Overlay Network for Multidimensional Attribute Space". 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709325342.
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Chen, Hsiu-Chin, e 陳秀琴. "SONMAS: A Structured Overlay Network for Multidimensional Attribute Space". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/74195466551214634183.
Abstract (sommario):
碩士國立清華大學
資訊系統與應用研究所
94
This thesis introduces SONMAS (Structured Overlay Network for Multidimensional Attribute Space), a multidimensional attribute-based peer-to-peer (P2P) system. SONMAS considers applications in which peers characterized by multidimensional attributes are discovered to satisfy given range queries. Traditional P2P systems either adopt a Gnutella-like interconnection and use flooding to search for matching peers, or implement a distributed hash table (DHT) on top of a structuralized interconnection. The former suffers from excessive flooding traffic, while the latter has difficulty of supporting range queries. SONMAS avoids these problems by interconnecting the peers according to their attributes. To deal with possible attribute collisions, SONMAS uses a special concept of attribute-ID-hybrid space to map each node to a unique point in the multidimensional space. SONMAS divides the attribute-ID-hybrid space into different levels of cells and interconnect the nodes according to their memberships to the cells. SONMAS is expected to work for applications with low dimensional attributes. Simulation results confirm its scalable routing efficiency and maintenance overhead as well as good fault-tolerance and resilience.
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Carletti, Marco. "Saliency-based approaches for multidimensional explainability of deep networks". Doctoral thesis, 2020. http://hdl.handle.net/11562/1016496.
Abstract (sommario):
In deep learning, visualization techniques extract the salient patterns exploited by deep networks to perform a task (e.g. image classification) focusing on single images. These methods allow a better understanding of these complex models, empowering the identification of the most informative parts of the input data. Beyond the deep network understanding, visual saliency is useful for many quantitative reasons and applications, both in the 2D and 3D domains, such as the analysis of the generalization capabilities of a classifier and autonomous navigation. In this thesis, we describe an approach to cope with the interpretability problem of a convolutional neural network and propose our ideas on how to exploit the visualization for applications like image classification and active object recognition. After a brief overview on common visualization methods producing attention/saliency maps, we will address two separate points: firstly, we will describe how visual saliency can be effectively used in the 2D domain (e.g. RGB images) to boost image classification performances: as a matter of fact, visual summaries, i.e. a compact representation of an ensemble of saliency maps, can be used to improve the classification accuracy of a network through summary-driven specializations. Then, we will present a 3D active recognition system that allows to consider different views of a target object, overcoming the single-view hypothesis of classical object recognition, making the classification problem much easier in principle. Here we adopt such attention maps in a quantitative fashion, by building a 3D dense saliency volume which fuses together saliency maps obtained from different viewpoints, obtaining a continuous proxy on which parts of an object are more discriminative for a given classifier. Finally, we will show how to inject this representations in a real world application, so that an agent (e.g. robot) can move knowing the capabilities of its classifier.
49
Alsukhni, Mohammad. "Interactive visualization of the collaborative research network". Thesis, 2012. http://hdl.handle.net/10155/207.
Abstract (sommario):
Social networks have been evolving over the past few years, leading to a rapid increase in the number and complexity of relationships among their entities. In this research, we focus on a large scale dataset known as the Digital Bibliography and Library Project or DBLP, which contains information on all publications that have been published in computer and information science related journals and conference proceedings. We model the DBLP dataset as a social network of research collaborations. DBLP is a structured and dynamic dataset stored in the XML file format; it contains over 850,000 authors and 2 million publications, and the resulting collaboration social network is a scale-free network. We define DBLP collaboration social network as a graph that consists of researchers as nodes and links representing the collaboration or co-authorship relationships among the researchers. In this work, we implement a data analysis algorithm called Multidimensional Scaling (MDS) to represent the degree of collaboration among the DBLP authors as Euclidean distances in 2-dimensional space in order to analyze, mine and understand the relational information in this large scale network in a visual way. MDS is a useful technique for data visualization and graph drawing methods, but it has high computational complexity for large scale graphs such as the DBLP graph. Therefore, we propose different solutions to overcome this problem, and improve the MDS performance. In addition, as the quality of the MDS result is measured by a metric known as the stress value, we use the steepest descent method to minimize the stress in an iterative process called stress optimization in order to generate the best geometric layout of the graph nodes in 2-dimensional space. We also propose a solution to further enhance the graph visualization by partitioning the graph into sub-graphs and using repelling forces among nodes within the same sub-graph. Finally, we developed a new visualization tool that can handle the large scale of the DBLP graph, and provides the user a number of significant features that allow them to explore, navigate and sift for information through the graph, such as graph scaling and graphical search functionality.UOIT
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Cheng, Y. Z., W. P. Wang, Geyong Min e J. X. Wang. "A new approach to designing firewall based on multidimensional matrix". 2013. http://hdl.handle.net/10454/9134.
Abstract (sommario):
NoFirewalls are crucial elements to enhance network security by examining the field value of every packet and decide whether to accept or discard the packet according to the firewall policy. However, the design of firewall policies, especially for enterprise networks, is complex and error-prone. This paper aims to propose an effective firewall design method to ensure the consistency, compactness and completeness of firewall rules. Specifically, we develop a new designing model, namely firewall design matrix, and the corresponding construction algorithm for mapping firewall rules to firewall design matrix. A firewall generation algorithm is proposed to generate the target firewall rules that are equivalent to the original ones while maintaining the completeness. Theoretical proof and extensive experiments on both real-world and synthetic firewalls are conducted to evaluate the performance of the proposed method. The results demonstrate that it can achieve a high compression ratio efficiently while maintaining the firewall rules conflict-free. Copyright (c) 2013 John Wiley & Sons, Ltd.