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Letteratura scientifica selezionata sul tema "Small World Network model"

Autore: Grafiati

Pubblicato: 23 settembre 2022

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Articoli di riviste sul tema "Small World Network model"

SHANKER, O., e TAD HOGG. "EPIDEMIOLOGY MODEL ON SHORTCUT AND SMALL WORLD NETWORKS". Modern Physics Letters B 23, n. 10 (20 aprile 2009): 1249–62. http://dx.doi.org/10.1142/s0217984909019387.

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We show that the behavior of an epidemiology model depends sensitively on the shortcut density in the shortcut network. This is consistent with an earlier work on other processes on the shortcut network. We analytically study the reason for the sensitivity. The shortcut network is similar to the small world network, and it has the advantage that the model dependence on the shortcut density can be analytically studied. The model would be relevant to the spread of diseases in human, animal, plant or other populations, to the spread of viruses in computer networks, or to the spread of social contagion in social networks. It would also be relevant in understanding the variations in the load on routers connecting different computer networks, as the network topology gets extended by the addition of new links, and in analyzing the placement of certain special sensors in a sensor network laid out in a non-random way with some shortcut links.

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Lee, Kang-won, Hee-kwan Uhm e Hye-jin Choe. "Tunable Network Generation Model for Small-World and Scale-Free Network". Journal of Korean Institute of Communications and Information Sciences 42, n. 7 (31 luglio 2017): 1392–401. http://dx.doi.org/10.7840/kics.2017.42.7.1392.

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Shang, Jun, Hao Qiang Liu, Qiang Liu e Zi Qi Liu. "Design of the Small World Model by NS2". Applied Mechanics and Materials 496-500 (gennaio 2014): 2338–41. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.2338.

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WSN is the network which is used mostly in the world nowadays, and it has the characteristics that lower cost and better functions than other kinds of the network, and the WSN network is built by the ordinary nodes and the super nodes.Theoretical study of the complex network is widely involved in the fields of computer networks, and the applied research becomes more and more important in the future. It has caused many academic attention about how to apply the complex network theory among the specific application in recent years. In the complex network theory, there has been a number of important research results about the use of the small-world network, scale-free network in the field of transportation.

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ZHU, LING-ZAN, BEI-BEI YIN, LEI ZHAO e KAI-YUAN CAI. "SCALE-FREE NETWORKS CAN BE LINEAR-WORLD". International Journal of Modern Physics B 25, n. 32 (30 dicembre 2011): 4593–603. http://dx.doi.org/10.1142/s0217979211059206.

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It was generally believed that scale-free networks would be small-world. In this paper, two models, named Model A and Model B, are proposed to show that certain scale-free networks can be linear-world instead of small-world. By linear-world, it means that the average path length L of the network grows linearly with the total number of nodes N, i.e., L~N. Model A generates a deterministic scale-free network with high assortativity and numerical simulations demonstrate that the network is linear-world when it satisfies degree exponent λ>1. Model B constructs a partially deterministic scale-free network, which is connected by identical small scale-free networks following certain rules. Analytical arguments and numerical simulations both yield L~N which suggests that it is also linear-world. It is further discussed in this paper that the network generated by Model Bcould be either correlated or uncorrelated. This suggests that, inconsistent with the results in related works, uncorrelated scale-free networks can also be linear-world.

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CAI, TIAN-YI, e ZHEN-YA LI. "ISING MODEL ON A SMALL WORLD NETWORK". International Journal of Modern Physics B 18, n. 17n19 (30 luglio 2004): 2575–78. http://dx.doi.org/10.1142/s0217979204025695.

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The properties of 2D Ising model on a small world network are investigated. It is found that Curie temperature increases with the increase of small world links. The relations between the Curie temperature and the concentration of small world links are found. The possibility of using Ising model to describe real network is discussed.

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Jia, Huanshen, Guona Hu e Haixing Zhao. "Topological Properties of a 3-Regular Small World Network". Discrete Dynamics in Nature and Society 2014 (2014): 1–4. http://dx.doi.org/10.1155/2014/160740.

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Complex networks have seen much interest from all research fields and have found many potential applications in a variety of areas including natural, social, biological, and engineering technology. The deterministic models for complex networks play an indispensable role in the field of network model. The construction of a network model in a deterministic way not only has important theoretical significance, but also has potential application value. In this paper, we present a class of 3-regular network model with small world phenomenon. We determine its relevant topological characteristics, such as diameter and clustering coefficient. We also give a calculation method of number of spanning trees in the 3-regular network and derive the number and entropy of spanning trees, respectively.

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WU, ZHENGPING, e RENMING WANG. "DISTANCE PREFERENCES SMALL-WORLD COMMUNICATION TOPOLOGY FOR AGENT NETWORK". International Journal of Modern Physics B 24, n. 11 (30 aprile 2010): 1489–99. http://dx.doi.org/10.1142/s0217979210054361.

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In multi-agent system (MAS), the communication topology of agent network plays a very important role in its collaboration. Small-world networks are the networks with high local clustering and small average path length, and the communication networks of MAS can be analyzed within the frame of small-world topology. Yet the real multiagent communication networks are abundant and the classical WS small-world model is not suitable for all cases. In this paper, two new small-world network models are presented. One is based on random graph substrate and local nodes preference reconnection and the other is based on regular graph substrate and long-range nodes preference reconnection. The characteristic of the network parameter such as the clustering coefficients, average path length, and eigenvalue λ2 and λn of the Laplacian matrix for these two models and WS model is studied. The consensus problem that based on these three models is also studied. An example is given and the conclusions are made in the end.

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Zhang, Tiankui, Jinlong Cao, Yue Chen, Laurie Cuthbert e Maged Elkashlan. "A Small World Network Model for Energy Efficient Wireless Networks". IEEE Communications Letters 17, n. 10 (ottobre 2013): 1928–31. http://dx.doi.org/10.1109/lcomm.2013.081313.131394.

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Schilling, Melissa. "A "Small-World" Network Model of Cognitive Insight". Creativity Research Journal 17, n. 2 (1 luglio 2005): 131–54. http://dx.doi.org/10.1207/s15326934crj1702&3_2.

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Schilling, Melissa A. "A "Small-World" Network Model of Cognitive Insight". Creativity Research Journal 17, n. 2-3 (luglio 2005): 131–54. http://dx.doi.org/10.1080/10400419.2005.9651475.

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Più fonti

Tesi sul tema "Small World Network model"

Taha, Samah M. Osman. "Small-world network models and their average path length". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/95834.

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Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Socially-based networks are of particular interest amongst the variety of communication networks arising in reality. They are distinguished by having small average path length and high clustering coefficient, and so are examples of small-world networks. This thesis studies both real examples and theoretical models of small-world networks, with particular attention to average path length. Existing models of small-world networks, due to Watts and Strogatz (1998) and Newman and Watts (1999a), impose boundary conditions on a one dimensional lattice, and rewire links locally and probabilistically in the former or probabilistically adding extra links in the latter. These models are investigated and compared with real-world networks. We consider a model in which randomness is provided by the Erdos-Rényi random network models superposed on a deterministic one dimensional structured network. We reason about this model using tools and results from random graph theory. Given a disordered network C(n, p) formed by adding links randomly with probability p to a one dimensional network C(n). We improve the analytical result regarding the average path length by showing that the onset of smallworld behaviour occurs if pn is bounded away from zero. Furthermore, we show that when pn tends to zero, C(n, p) is no longer small-world. We display that the average path length in this case approaches infinity with the network order. We deduce that at least εn (where ε is a constant bigger than zero) random links should be added to a one dimensional lattice to ensure average path length of order log n.
AFRIKAANSE OPSOMMING: Sosiaal-baseerde netwerke is van besondere belang onder die verskeidenheid kommunikasie netwerke. Hulle word onderskei deur ’n klein gemiddelde skeidingsafstand en hoë samedrommingskoëffisiënt, en is voorbeelde van kleinwêreld netwerke. Hierdie verhandeling bestudeer beide werklike voorbeelde en teoretiese modelle van klein-wêreld netwerke, met besondere aandag op die gemiddelde padlengte. Bestaande modelle van klein-wêreld netwerke, te danke aan Watts en Strogatz (1998) en Newman en Watts (1999a), voeg randvoorwaardes by tot eendimensionele roosters, en herbedraad nedwerkskakels gebaseer op lokale kennis in die eerste geval en voeg willekeurig ekstra netwerkskakels in die tweede. Hierdie modelle word ondersoek en vergelyk met werklike-wêreld netwerke. Ons oorweeg ’n prosedure waarin willekeurigheid verskaf word deur die Erdös- Renyi toevalsnetwerk modelle wat op ’n een-dimensionele deterministiese gestruktureerde netwerk geimposeer word. Ons redeneer oor hierdie modelle deur gebruik te maak van gereedskap en resultate toevalsgrafieke teorie. Gegewe ’n wanordelike netwerk wat gevorm word deur skakels willekeurig met waarskynlikheid p tot ‘n een-dimensionele netwerk C(n) toe te voeg, verbeter ons die analitiese resultaat ten opsigte van die gemiddelde padlengte deur te wys dat die aanvang van klein-wêreld gedrag voorkom wanneer pn weg van nul begrens is. Verder toon ons dat, wanneer pn neig na nul, C(n, p) nie meer klein-wêreld is nie. Ons toon dat die gemiddelde padlengte in hierdie geval na oneindigheid streef saam met die netwerk groote. Ons lei af dat ten minste εn (waar εn n konstante groter as nul is) ewekansige skakels bygevoeg moet word by ’n een-dimensionele rooster om ‘n gemiddelde padlengte van orde log n te verseker.

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Vieira, Israel Teixeira. "Small world network models of the dynamics of HIV infection". Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433933.

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Hedefalk, Finn. "Robustness of Spatial Databases: Using Network Analysis on GIS Data Models". Thesis, University of Gävle, Department of Technology and Built Environment, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-6625.

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Demands on the quality and reliability of Volunteered Geographic Information have increased because of its rising popularity. Due to the less controlled data entry, there is a risk that people provide false or inaccurate information to the database. One factor that affects the effect of such updates is the network structure of the database schema, which might reveal the database’s robustness against different kinds of false updates. Therefore, network analyses are needed. The aim is to analyse GIS data models, stored in UML class diagrams, for scale-free and small-world properties. Moreover, a robustness analysis is to be carried out on selected data models in order to find out their error and attack tolerance against, for example, false updates. Three graphs were specified from the UML class diagrams: (1) class graphs: classes as nodes and their interactive relationships as connections; (2) attribute graphs: classes and attributes as nodes, with connections between the classes and their attributes; and (3) schema graphs: attributes as nodes and their interactive relationships inside and outside the tables as links. The analysed class diagrams were stored in XMI, and therefore transformed with XSLT to the Pajek network format. Thereafter, small-world and scale-free analyses as well as a robustness analysis were performed on the graphs.

The results from the scale-free analyses showed no strict power-laws. Nevertheless, the classes’ relationships and attributes, and the betweenness in the schema graphs were long-tailed distributed. Furthermore, the schema graphs had small-world properties, and the analysed class and schema graphs were robust against errors but fragile against attacks. In a network structure perspective, these results indicate that false updates on random tables of a database should usually do little harm, but falsely updating the most central cells or tables may cause big damage. Consequently, it may be necessary to monitor and constrain sensitive cells and tables in order to protect them from attacks

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Luo, Hongwei, e Hongwei luo@rmit edu au. "Modelling and simulation of large-scale complex networks". RMIT University. Mathematical and Geospatial Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080506.142224.

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Real-world large-scale complex networks such as the Internet, social networks and biological networks have increasingly attracted the interest of researchers from many areas. Accurate modelling of the statistical regularities of these large-scale networks is critical to understand their global evolving structures and local dynamical patterns. Traditionally, the Erdos and Renyi random graph model has helped the investigation of various homogeneous networks. During the past decade, a special computational methodology has emerged to study complex networks, the outcome of which is identified by two models: the Watts and Strogatz small-world model and the Barabasi-Albert scale-free model. At the core of the complex network modelling process is the extraction of characteristics of real-world networks. I have developed computer simulation algorithms for study of the properties of current theoretical models as well as for the measurement of two real-world complex networks, which lead to the isolation of three complex network modelling essentials. The main contribution of the thesis is the introduction and study of a new General Two-Stage growth model (GTS Model), which aims to describe and analyze many common-featured real-world complex networks. The tools we use to create the model and later perform many measurements on it consist of computer simulations, numerical analysis and mathematical derivations. In particular, two major cases of this GTS model have been studied. One is named the U-P model, which employs a new functional form of the network growth rule: a linear combination of preferential attachment and uniform attachment. The degree distribution of the model is first studied by computer simulation, while the exact solution is also obtained analytically. Two other important properties of complex networks: the characteristic path length and the clustering coefficient are also extensively investigated, obtaining either analytically derived solutions or numerical results by computer simulations. Furthermore, I demonstrate that the hub-hub interaction behaves in effect as the link between a network's topology and resilience property. The other is called the Hybrid model, which incorporates two stages of growth and studies the transition behaviour between the Erdos and Renyi random graph model and the Barabasi-Albert scale-free model. The Hybrid model is measured by extensive numerical simulations focusing on its degree distribution, characteristic path length and clustering coefficient. Although either of the two cases serves as a new approach to modelling real-world large-scale complex networks, perhaps more importantly, the general two-stage model provides a new theoretical framework for complex network modelling, which can be extended in many ways besides the two studied in this thesis.

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Jiang, Jian. "Modeling of complex network, application to road and cultural networks". Phd thesis, Université du Maine, 2011. http://tel.archives-ouvertes.fr/tel-00691129.

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Many complex systems arising from nature and human society can be described as complex networks. In this dissertation, on the basis of complex network theory, we pay attention to the topological structure of complex network and the dynamics on it. We established models to investigate the influences of the structure on the dynamics of networks and to shed light on some peculiar properties of complex systems. This dissertation includes four parts. In the first part, the empirical properties (degree distribution, clustering coefficient, diameter, and characteristic path length) of urban road network of Le Mans city in France are studied. The degree distribution shows a double power-law which we studied in detail. In the second part, we propose two models to investigate the possible mechanisms leading to the deviation from simple power law. In the first model, probabilistic addition of nodes and links, and rewiring of links are considered; in the second one, only random and preferential link growth is included. The simulation results of the modelling are compared with the real data. In the third part,the probabilistic uncertainty behavior of double power law distribution is investigated. The network optimization and optimal design of scale free network to random failures are discussed from the viewpoint of entropy maximization. We defined equilibrium network ensemble as stationary ensembles of graphs by using some thermodynamics like notions such as "energy", "temperature", "free energy" for network. In the forth part, an union-division model is established to investigate the time evolution of certain networks like cultural or economical networks. In this model, the nodes represent, for example, the cultures. Several quantities such as richness, age, identity, ingredient etc. are used to parameterize the probabilistic evolution of the network. The model offers a long term view on the apparently periodic dynamics of an ensemble of cultural or economic entities in interaction.

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Rimer, Suvendi Chinnappen. "Energy efficient communication models in wireless sensor and actor networks". Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/23253.

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Sensor nodes in a wireless sensor network (WSN) have a small, non-rechargeable power supply. Each message transmission or reception depletes a sensor node’s energy. Many WSN applications are ad-hoc deployments where a sensor node is only aware of its immediate neighbours. The lack of a predefined route path and the need to restrict the amount of communication that occurs within the application area impose constraints on WSNs not prevalent in other types of networks. An area of active research has been how to notify the central sink (or monitoring hub) about an event in real-time by utilising the minimum number of messages to route a message from a source node to the destination sink node. In this thesis, strategies to limit communication within a WSN application area, while ensuring that events are reported on and responded to in real-time, is presented. A solution based on modelling a WSN as a small world network and then transmitting an initialisation message (IM) on network start-up to create multiple route paths from any sensor node to one or more sinks is proposed. The reason for modelling a WSN as a small world network is to reduce the number of nodes required to re-transmit a message from a source sensor node to a sink. The purpose of sending an IM at network start-up is to ensure that communication within the WSN is minimised. When routing a message to a static sink, the nodes closest to the static sink receive a disproportionate number of messages, resulting in their energy being consumed earlier. The use of mobile sinks has been proposed but to our knowledge no studies have been undertaken on the paths these mobile sinks should follow. An algorithm to determine the optimum path for mobile sinks to follow in a WSN application area is described. The purpose of an optimum path is to allow more equitable usage of all nodes to transfer an event message to a mobile sink. The idea of using multiple static sinks placed at specific points in the small world model is broadened to include using multiple mobile sinks called actors to move within a WSN application area and respond to an event in real-time. Current coordination solutions to determine which actor(s) must respond to the event result in excessive message communication and limit the real-time response to an event. An info gap decision theory (IGDT) model to coordinate which actor or set of actors should respond to the event is described. A comparison of the small world routing (SWR) model against routing using flooding and gossiping shows that the SWR model significantly reduces the number of messages transmitted within the network. An analysis of the number of IMs transmitted and received at individual node level shows that prudent selection of the hop count (number of additional nodes required to route a message to sink) to a sink node will result in a reduced number of messages transmitted and received per node within the network. The use of the IGDT model results in a robust decision on the actor(s) chosen to respond to an event even when uncertainty about the location and available energy of other actor(s) exists.
Thesis (PhD(Eng))--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
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Nguyen, Anh Dung. "Contributions to Modeling, Structural Analysis, and Routing Performance in Dynamic Networks". Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2013. http://tel.archives-ouvertes.fr/tel-00908502.

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Cette thèse apporte des contributions à la modélisation, compréhension ainsi qu'à la communication efficace d'information dans les réseaux dynamiques peuplant la périphérie de l'Internet. Par réseaux dynamiques, nous signifions les réseaux pouvant être modélisés par des graphes dynamiques dans lesquels noeuds et liens évoluent temporellement. Dans la première partie de la thèse, nous proposons un nouveau modèle de mobilité - STEPS - qui permet de capturer un large spectre de comportement de mobilité humains. STEPS mets en oeuvre deux principes fondamentaux de la mobilité humaine : l'attachement préférentiel à une zone de prédilection et l'attraction vers une zone de prédilection. Nous proposons une modélisation markovienne de ce modèle de mobilité. Nous montrons que ce simple modèle paramétrique est capable de capturer les caractéristiques statistiques saillantes de la mobilité humaine comme la distribution des temps d'inter-contacts et de contacts. Dans la deuxième partie, en utilisant STEPS, nous analysons les propriétés comportementales et structurelles fondamentales des réseaux opportunistes. Nous redéfinissons dans le contexte des réseaux dynamiques la notion de structure petit monde et montrons comment une telle structure peut émerger. En particulier, nous montrons que les noeuds fortement dynamiques peuvent jouer le rôle de ponts entre les composants déconnectés, aident à réduire significativement la longueur du chemin caractéristique du réseau et contribuent à l'émergence du phénomène petit-monde dans les réseaux dynamiques. Nous proposons une façon de modéliser ce phénomène sous STEPS. À partir d'un réseau dynamique régulier dans lequel les noeuds limitent leur mobilité à leurs zones préférentielles respectives. Nous recablons ce réseau en injectant progressivement des noeuds nomades se déplaçant entre plusieurs zones. Nous montrons que le pourcentage de tels nœuds nomades est de 10%, le réseau possède une structure petit monde avec un fort taux de clusterisation et un faible longueur du chemin caractéristique. La troisième contribution de cette thèse porte sur l'étude de l'impact du désordre et de l'irrégularité des contacts sur la capacité de communication d'un réseau dynamique. Nous analysons le degré de désordre de réseaux opportunistes réels et montrons que si exploité correctement, celui-ci peut améliorer significativement les performances du routage. Nous introduisons ensuite un modèle permettant de capturer le niveau de désordre d'un réseau dynamique. Nous proposons deux algorithmes simples et efficaces qui exploitent la structure temporelle d'un réseau dynamique pour délivrer les messages avec un bon compromis entre l'usage des ressources et les performances. Les résultats de simulations et analytiques montrent que ce type d'algorithme est plus performant que les approches classiques. Nous mettons également en évidence aussi la structure de réseau pour laquelle ce type d'algorithme atteint ses performances optimum. Basé sur ce résultat théorique nous proposons un nouveau protocole de routage efficace pour les réseaux opportunistes centré sur le contenu. Dans ce protocole, les noeuds maintiennent, via leurs contacts opportunistes, une fonction d'utilité qui résume leur proximité spatio-temporelle par rapport aux autres noeuds. En conséquence, router dans un tel contexte se résume à suivre le gradient de plus grande pente conduisant vers le noeud destination. Cette propriété induit un algorithme de routage simple et efficace qui peut être utilisé aussi bien dans un contexte d'adressage IP que de réseau centré sur les contenus. Les résultats de simulation montrent que ce protocole superforme les protocoles de routage classiques déjà définis pour les réseaux opportunistes. La dernière contribution de cette thèse consiste à mettre en évidence une application potentielle des réseaux dynamiques dans le contexte du " mobile cloud computing ". En utilisant les techniques d'optimisation particulaires, nous montrons que la mobilité peut augmenter considérablement la capacité de calcul des réseaux dynamiques. De plus, nous montrons que la structure dynamique du réseau a un fort impact sur sa capacité de calcul.

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Younsi, Fatima-Zohra. "Mise en place d'un Système d'Information Décisionnel pour le suivi et la prévention des épidémies". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE2005/document.

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Les maladies infectieuses représentent aujourd’hui un problème majeur de santé publique. Devant l’augmentation des résistances bactériennes, l’émergence de nouveaux pathogènes et la propagation rapide de l’épidémie, le suivi et la surveillance de la transmission de la maladie devient particulièrement importants. Face à une telle menace, la société doit se préparer à l'avance pour réagir rapidement et efficacement si une telle épidémie est déclarée. Cela nécessite une mise en place des dispositifs de suivi et de prévention. Dans ce contexte, nous nous intéressons, dans le présent travail, à l’élaboration d’un Système d’Information Décisionnel Spatio-temporel pour le suivi et la surveillance du phénomène de propagation de l’épidémie de la grippe saisonnière au sein de la population de la ville d’Oran (Algérie). L’objectif de ce système est double : il consiste, d’une part, à comprendre comment l’épidémie se propage par l’utilisation du réseau social Small World (SW) et du modèle à compartiments d’épidémie SEIR (Susceptible-Exposed-Infected-Removed), et d’autre part, à stocker dans un entrepôt les données multiples tout en les analysant par un outil d’analyse en ligne de donnée Spatiale dit SOLAP (Spatial On-Line Analytical Processing)
Today, infectious diseases represent a major public health problem. With the increase of bacterial resistance, the emergence of new pathogens and the rapid spread of epidemic, monitoring and surveillance of disease transmission becomes important. In the face of such a threat, the society must prepare in advance to respond quickly and effectively if an outbreak is declared. This requires setting up monitoring mechanisms and prevention.In this context, we are particularly interested by development a Spatiotemporal decision support system for monitoring and preventing the phenomenon of seasonal influenza epidemic spread in the population of Oran (city at Algeria).The objective of this system is twofold: on one hand, to understand how epidemic is spreading through the social network by using SEIR (Susceptible-Exposed-Infected-Removed) compartmental model within Small World network, and on the other hand, to store multiple data in data warehouse and analyzing it by a specific online analysis tool Spatial OLAP (Spatial on-line Analytical Processing)

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Castro, Paulo Alexandre de. "Rede complexa e criticalidade auto-organizada: modelos e aplicações". Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-14012008-165356/.

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Modelos e teorias científicas surgem da necessidade do homem entender melhor o funcionamento do mundo em que vive. Constantemente, novos modelos e técnicas são criados com esse objetivo. Uma dessas teorias recentemente desenvolvida é a da Criticalidade Auto-Organizada. No Capítulo 2 desta tese, apresentamos uma breve introdução a Criticalidade Auto-Organizada. Tendo a criticalidade auto-organizada como pano de fundo, no Capítulo 3, estudamos a dinâmica Bak-Sneppen (e diversas variantes) e a comparamos com alguns algoritmos de otimização. Apresentamos no Capítulo 4, uma revisão histórica e conceitual das redes complexas. Revisamos alguns importantes modelos tais como: Erdös-Rényi, Watts-Strogatz, de configuração e Barabási-Albert. No Capítulo 5, estudamos o modelo Barabási-Albert não-linear. Para este modelo, obtivemos uma expressão analítica para a distribuição de conectividades P(k), válida para amplo espectro do espaço de parâmetros. Propusemos também uma forma analítica para o coeficiente de agrupamento, que foi corroborada por nossas simulações numéricas. Verificamos que a rede Barabási-Albert não-linear pode ser assortativa ou desassortativa e que, somente no caso da rede Barabási-Albert linear, ela é não assortativa. No Capítulo 6, utilizando dados coletados do CD-ROM da revista Placar, construímos uma rede bastante peculiar -- a rede do futebol brasileiro. Primeiramente analisamos a rede bipartida formada por jogadores e clubes. Verificamos que a probabilidade de que um jogador tenha participado de M partidas decai exponencialmente com M, ao passo que a probabilidade de que um jogador tenha marcado G gols segue uma lei de potência. A partir da rede bipartida, construímos a rede unipartida de jogadores, que batizamos de rede de jogadores do futebol brasileiro. Nessa rede, determinamos várias grandezas: o comprimento médio do menor caminho e os coeficientes de agrupamento e de assortatividade. A rede de jogadores de futebol brasileiro nos permitiu analisar a evolução temporal dessas grandezas, uma oportunidade rara em se tratando de redes reais.
Models and scientific theories arise from the necessity of the human being to better understand how the world works. Driven by this purpose new models and techniques have been created. For instance, one of these theories recently developed is the Self-Organized Criticality, which is shortly introduced in the Chapter 2 of this thesis. In the framework of the Self-Organized Criticality theory, we investigate the standard Bak-Sneppen dynamics as well some variants of it and compare them with optimization algorithms (Chapter 3). We present a historical and conceptual review of complex networks in the Chapter 4. Some important models like: Erdös-Rényi, Watts-Strogatz, configuration model and Barabási-Albert are revised. In the Chapter 5, we analyze the nonlinear Barabási-Albert model. For this model, we got an analytical expression for the connectivity distribution P(k), which is valid for a wide range of the space parameters. We also proposed an exact analytical expression for the clustering coefficient which corroborates very well with our numerical simulations. The nonlinear Barabási-Albert network can be assortative or disassortative and only in the particular case of the linear Barabási-Albert model, the network is no assortative. In the Chapter 6, we used collected data from a CD-ROM released by the magazine Placar and constructed a very peculiar network -- the Brazilian soccer network. First, we analyzed the bipartite network formed by players and clubs. We find out that the probability of a footballer has played M matches decays exponentially with M, whereas the probability of a footballer to score G gols follows a power-law. From the bipartite network, we built the unipartite Brazilian soccer players network. For this network, we determined several important quantities: the average shortest path length, the clustering coefficient and the assortative coefficient. We were also able to analise the time evolution of these quantities -- which represents a very rare opportunity in the study of real networks.

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Nguyen, Anh-Dung. "Contributions to modeling, structural analysis, and routing performance in dynamic networks". Phd thesis, Toulouse, INPT, 2013. http://oatao.univ-toulouse.fr/9725/1/nguyen.pdf.

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This thesis contributes to the modeling, understanding and efficient communication in dynamic networks populating the periphery of the Internet. By dynamic networks, we refer to networks that can be modeled by dynamic graphs in which nodes and links change temporally. In the first part of the thesis, we propose a new mobility model - STEPS - which captures a wide spectrum of human mobility behavior. STEPS implements two fundamental principles of human mobility: preferential attachment and attractor. We show that this simple parametric model is able to capture the salient statistical properties of human mobility such as the distribution of inter-contact/contact time. In the second part, using STEPS, we analyze the fundamental behavioral and structural properties of opportunistic networks. We redefine in the context of dynamic networks the concept of small world structure and show how such a structure can emerge. In particular, we show that highly dynamic nodes can play the role of bridges between disconnected components, helping to significantly reduce the length of network path and contribute to the emergence of small-world phenomenon in dynamic networks. We propose a way to model this phenomenon in STEPS. From a regular dynamic network in which nodes limit their mobility to their respective preferential areas. We rewire this network by gradually injecting highly nomadic nodes moving between different areas. We show that when the ratio of such nomadic nodes is around 10%, the network has small world structure with a high degree of clustering and a low characteristic path length. The third contribution of this thesis is the study of the impact of disorder and contact irregularity on the communication capacity of a dynamic network. We analyze the degree of disorder of real opportunistic networks and show that if used correctly, it can significantly improve routing performances. We then introduce a model to capture the degree of disorder in a dynamic network. We propose two simple and efficient algorithms that exploit the temporal structure of a dynamic network to deliver messages with a good tradeoff between resource usage and performance. The simulation and analytical results show that this type of algorithm is more efficient than conventional approaches. We also highlight also the network structure for which this type of algorithm achieves its optimum performance. Based on this theoretical result, we propose a new efficient routing protocol for content centric opportunistic networks. In this protocol, nodes maintain, through their opportunistic contacts, an utility function that summarizes their spatio-temporal proximity to other nodes. As a result, routing in this context consists in following the steepest slopes of the gradient field leading to the destination node. This property leads to a simple and effective algorithm routing that can be used both in the context of IP networks and content centric networks. The simulation results show that this protocol outperforms traditional routing protocols already defined for opportunistic networks. The last contribution of this thesis is to highlight the potential application of dynamic networks in the context of "mobile cloud computing." Using the particle optimization techniques, we show that mobility can significantly increase the processing capacity of dynamic networks. In addition, we show that the dynamic structure of the network has a strong impact on its processing capacity.

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Libri sul tema "Small World Network model"

Watts, Duncan J. Small worlds: The dynamics of networks between order and randomness. Princeton, N.J: Princeton University Press, 1999.

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Dawo, Titus. First world development: A model for a development communication network. Birmingham: University of Central England in Birmingham, 2000.

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Cohen, Lauren. The small world of investing: Board connections and mutual fund returns. Cambridge, Mass: National Bureau of Economic Research, 2007.

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Cohen, Lauren. The small world of investing: Board connections and mutual fund returns. Cambridge, MA: National Bureau of Economic Research, 2007.

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D'Autrechy, C. Lynne. Autoplan: A self-processing network model for an extended blocks world planning environment. College Park, Md: University of Maryland, 1990.

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D'Autrechy, C. Lynne. Autoplan: A self-processing network model for an extended blocks world planning environment. College Park, Md: University of Maryland, 1990.

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Boyle, Edward H. Chromium availability in market economy countries and network flow model analysis of world chromium supply. [PGH, PA]: U.S. Dept. of the Interior, Bureau of Mines, 1993.

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Large networks and graph limits. Providence, Rhode Island: American Mathematical Society, 2012.

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Lowery, Joseph. Netrepreneur: The dimension of transferring your business model to the Internet. Indianapolis, Ind: Que, 1998.

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Bardazzi, Rossella, e Leonardo Ghezzi, a cura di. Macroeconomic modelling for policy analysis. Florence: Firenze University Press, 2013. http://dx.doi.org/10.36253/978-88-6655-396-0.

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Over the last 30 years, the Inforum approach to macro modelling has been shared by economists worldwide. Researchers have focussed much of their efforts to developing a linked system of international interindustry models with a consistent methodology. A world-wide network of research associates use the same methods and software obtaining comparable results. The XXth Inforum World Conference was held in Florence in September 2012 and this book contains a selection of papers presented during that Conference. All these contributions are aimed at policymakers, stakeholders, and applied economists. Some papers are devoted to specific topics (total factor productivity, energy issues, external linkages, demographic changes) and some others are oriented to macro model building and simulations.

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Capitoli di libri sul tema "Small World Network model"

Yang, Ting, Dinghua Zhang, Bing Chen e Shan Li. "The Small-World Network Model of Mixed Production Line". In Intelligent Robotics and Applications, 22–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-16587-0_3.

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Chen, Qiao-ling, Liang Chen, Zhi-Qiang Sun e Zhi-juan Jia. "An Epidemic Propagation Model with Saturated Infection Rate on a Small World Network". In Lecture Notes in Computer Science, 34–42. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-22053-6_4.

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Andersen, Reid, Fan Chung e Lincoln Lu. "Analyzing the Small World Phenomenon Using a Hybrid Model with Local Network Flow (Extended Abstract)". In Algorithms and Models for the Web-Graph, 19–30. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30216-2_2.

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De Nigris, Sarah, e Xavier Leoncini. "Emergence of Long Range Order in the XY Model on Diluted Small World Networks". In Proceedings of the European Conference on Complex Systems 2012, 145–54. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-00395-5_22.

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Zhang, Ruicheng, e Peipei Wang. "The Model of NW Multilayer Feedforward Small-World Artificial Neural Networks and It’s Applied". In Communications in Computer and Information Science, 209–16. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-27452-7_28.

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Cao, Huan, Lili Wu, Yue Chen, Yongtao Su, Zhengchao Lei e Chunping Zhao. "Analysis on the Security of Satellite Internet". In Communications in Computer and Information Science, 193–205. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-33-4922-3_14.

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AbstractSatellite Internet (SI) is a new way to provide internet access all over the world. It will bring great convenience to international communication. Compared with the traditional communication networks, SI has a significant change in network architecture and communication model, which will have an important impact on national information network security. For example, the global interconnected SI consists of a large number of small satellites and each satellite has multi-beams to cover a vast area, which leads to the disorderly flow of information across the border, and greatly increases the difficulty of network protection. Therefore, it is necessary to closely track the development of SI and analyze security problems brought by SI. In this paper, we analyze the security risks of SI from the perspective of national security, network security and equipment security, and thirteen security issues have been summarized to provide reference for the healthy development of SI industry.

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Yu, Yu, Yao Chen e Qinfen Shi. "Small-World Network and Knowledge Sharing". In Strategy and Performance of Knowledge Flow, 121–31. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77926-3_9.

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Dey, Paramita, Maitreyee Ganguly, Priya Sengupta e Sarbani Roy. "Small World Network Formation and Characterization of Sports Network". In Advances in Intelligent Systems and Computing, 619–27. Singapore: Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-3153-3_61.

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Matsumoto, Kautsuyoshi, Minoru Uehara e Hideki Mori. "Fault Tolerance for Small-World Cellular Neural Networks". In Network-Based Information Systems, 223–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-85693-1_24.

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Kizhakkethil, Priya. "Reimagining Small World: A Preliminary Model". In Sustainable Digital Communities, 88–95. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43687-2_7.

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Atti di convegni sul tema "Small World Network model"

Mori, Hideki, Minoru Uehara e Katsuyoshi Matsumoto. "Parallel Architectures with Small World Network Model". In 2015 IEEE 29th International Conference on Advanced Information Networking and Applications Workshops (WAINA). IEEE, 2015. http://dx.doi.org/10.1109/waina.2015.84.

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Ziqian Dong, Zheng Wang, Wen Xie, Obinna Emelumadu, Chuanbi Lin e Roberto Rojas-Cessa. "An experimental study of small world network model for wireless networks". In 2015 36th IEEE Sarnoff Symposium. IEEE, 2015. http://dx.doi.org/10.1109/sarnof.2015.7324646.

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Guan, Jinting, Meishuang Tang, Guangzao Huang, Wenbing Zhu, Sun Zhou e Guoli Ji. "A new small-world network model for instant messaging chat network". In 2016 11th System of Systems Engineering Conference (SoSE). IEEE, 2016. http://dx.doi.org/10.1109/sysose.2016.7542921.

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Gengzhong, Zheng, e Liu Qiumei. "A Survey of Wireless Sensor Networks Based on Small World Network Model". In 2010 International Conference on Electrical and Control Engineering (ICECE 2010). IEEE, 2010. http://dx.doi.org/10.1109/icece.2010.647.

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Jingnan, Li, Li Pengfei e Liu Kai. "Research on UAV communication network topology based on small world network model". In 2017 IEEE International Conference on Unmanned Systems (ICUS). IEEE, 2017. http://dx.doi.org/10.1109/icus.2017.8278386.

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Ridong Bai. "Topological optimization based on small world network model in wireless sensor network". In 2011 2nd International Conference on Control, Instrumentation, and Automation (ICCIA). IEEE, 2011. http://dx.doi.org/10.1109/icciautom.2011.6183960.

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Bai, Ridong. "Topological Optimization Based on Small World Network Model in Wireless Sensor Network". In 2013 2nd International Conference on Intelligent System and Applied Material. Ottawa: EDUGAIT Press, 2013. http://dx.doi.org/10.12696/gsam.2013.0903.

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Zhao, Wei, e Xusong Xu. "CSM Homogeneous-Interaction Innovation Model Based on Small-World Network". In 2011 International Conference on Management and Service Science (MASS 2011). IEEE, 2011. http://dx.doi.org/10.1109/icmss.2011.5997916.

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Li, Bo, Yan Jiang, Xiu Wen Yang e Qiong Lin. "Negative information transmission model based on the small world network". In 2013 10th International Computer Conference on Wavelet Active Media Technology and Information Processing (ICCWAMTIP). IEEE, 2013. http://dx.doi.org/10.1109/iccwamtip.2013.6716595.

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Ma, Fei, Jing Su e Bing Yao. "One small-world scale-free network model having tuned parameters". In 2017 IEEE 2nd Advanced Information Technology, Electronic and Automation Control Conference (IAEAC). IEEE, 2017. http://dx.doi.org/10.1109/iaeac.2017.8053985.

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Rapporti di organizzazioni sul tema "Small World Network model"

Cheng, Karen, David Crary, J. Rodriguez e Darren R. Oldson. A Small-World Network Model of Disease Transmission. Fort Belvoir, VA: Defense Technical Information Center, dicembre 2011. http://dx.doi.org/10.21236/ada555260.

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Yu, Haichao, Haoxiang Li, Honghui Shi, Thomas S. Huang e Gang Hua. Any-Precision Deep Neural Networks. Web of Open Science, dicembre 2020. http://dx.doi.org/10.37686/ejai.v1i1.82.

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We present Any-Precision Deep Neural Networks (Any- Precision DNNs), which are trained with a new method that empowers learned DNNs to be flexible in any numerical precision during inference. The same model in runtime can be flexibly and directly set to different bit-width, by trun- cating the least significant bits, to support dynamic speed and accuracy trade-off. When all layers are set to low- bits, we show that the model achieved accuracy compara- ble to dedicated models trained at the same precision. This nice property facilitates flexible deployment of deep learn- ing models in real-world applications, where in practice trade-offs between model accuracy and runtime efficiency are often sought. Previous literature presents solutions to train models at each individual fixed efficiency/accuracy trade-off point. But how to produce a model flexible in runtime precision is largely unexplored. When the demand of efficiency/accuracy trade-off varies from time to time or even dynamically changes in runtime, it is infeasible to re-train models accordingly, and the storage budget may forbid keeping multiple models. Our proposed framework achieves this flexibility without performance degradation. More importantly, we demonstrate that this achievement is agnostic to model architectures. We experimentally validated our method with different deep network backbones (AlexNet-small, Resnet-20, Resnet-50) on different datasets (SVHN, Cifar-10, ImageNet) and observed consistent results.

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Schulz, Jan, Daniel Mayerhoffer e Anna Gebhard. A Network-Based Explanation of Perceived Inequality. Otto-Friedrich-Universität, 2021. http://dx.doi.org/10.20378/irb-49393.

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Across income groups and countries, the public perception of economic inequality and many other macroeconomic variables such as inflation or unemployment rates is spectacularly wrong. These misperceptions have far-reaching consequences, as it is perceived inequality, not actual inequality informing redistributive preferences. The prevalence of this phenomenon is independent of social class and welfare regime, which suggests the existence of a common mechanism behind public perceptions. We propose a network-based explanation of perceived inequality building on recent advances in random geometric graph theory. The literature has identified several stylised facts on how individual perceptions respond to actual inequality and how these biases vary systematically along the income distribution. Our generating mechanism can replicate all of them simultaneously. It also produces social networks that exhibit salient features of real-world networks; namely, they cannot be statistically distinguished from small-world networks, testifying to the robustness of our approach. Our results, therefore, suggest that homophilic segregation is a promising candidate to explain inequality perceptions with strong implications for theories of consumption behaviour.

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Hsueh, Gary, David Czerwinski, Cristian Poliziani, Terris Becker, Alexandre Hughes, Peter Chen e Melissa Benn. Using BEAM Software to Simulate the Introduction of On-Demand, Automated, and Electric Shuttles for Last Mile Connectivity in Santa Clara County. Mineta Transportation Institute, gennaio 2021. http://dx.doi.org/10.31979/mti.2021.1822.

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Despite growing interest in low-speed automated shuttles, pilot deployments have only just begun in a few places in the U.S., and there is a lack of studies that estimate the impacts of a widespread deployment of automated shuttles designed to supplement existing transit networks. This project estimated the potential impacts of automated shuttles based on a deployment scenario generated for a sample geographic area: Santa Clara County, California. The project identified sample deployment markets within Santa Clara County using a GIS screening exercise; tested the mode share changes of an automated shuttle deployment scenario using BEAM, an open-source beta software developed at the Lawrence Berkeley National Laboratory to run traffic simulations with MATSim; elaborated the model outputs within the R environment; and then estimated the related impacts. The main findings have been that the BEAM software, despite still being in its beta version, was able to model a scenario with the automated shuttle service: this report illustrates the potential of the software and the lessons learned. Regarding transportation aspects, the model estimated automated shuttle use throughout the county, with a higher rate of use in the downtown San José area. The shuttles would be preferred mainly by people who had been using gasoline-powered ride hail vehicles for A-to-B trips or going to the bus stop, as well as walking trips and a few car trips directed to public transport stops. As a result, the shuttles contributed to a small decrease in emissions of air pollutants, provided a competitive solution for short trips, and increased the overall use of the public transport system. The shuttles also presented a solution for short night trips—mainly between midnight and 2 am—when there are not many options for moving between points A and B. The conclusion is that the automated shuttle service is a good solution in certain contexts and can increase public transit ridership overall.

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McKenna, Patrick, e Mark Evans. Emergency Relief and complex service delivery: Towards better outcomes. Queensland University of Technology, giugno 2021. http://dx.doi.org/10.5204/rep.eprints.211133.

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Emergency Relief (ER) is a Department of Social Services (DSS) funded program, delivered by 197 community organisations (ER Providers) across Australia, to assist people facing a financial crisis with financial/material aid and referrals to other support programs. ER has been playing this important role in Australian communities since 1979. Without ER, more people living in Australia who experience a financial crisis might face further harm such as crippling debt or homelessness. The Emergency Relief National Coordination Group (NCG) was established in April 2020 at the start of the COVID-19 pandemic to advise the Minister for Families and Social Services on the implementation of ER. To inform its advice to the Minister, the NCG partnered with the Institute for Governance at the University of Canberra to conduct research to understand the issues and challenges faced by ER Providers and Service Users in local contexts across Australia. The research involved a desktop review of the existing literature on ER service provision, a large survey which all Commonwealth ER Providers were invited to participate in (and 122 responses were received), interviews with a purposive sample of 18 ER Providers, and the development of a program logic and theory of change for the Commonwealth ER program to assess progress. The surveys and interviews focussed on ER Provider perceptions of the strengths, weaknesses, future challenges, and areas of improvement for current ER provision. The trend of increasing case complexity, the effectiveness of ER service delivery models in achieving outcomes for Service Users, and the significance of volunteering in the sector were investigated. Separately, an evaluation of the performance of the NCG was conducted and a summary of the evaluation is provided as an appendix to this report. Several themes emerged from the review of the existing literature such as service delivery shortcomings in dealing with case complexity, the effectiveness of case management, and repeat requests for service. Interviews with ER workers and Service Users found that an uplift in workforce capability was required to deal with increasing case complexity, leading to recommendations for more training and service standards. Several service evaluations found that ER delivered with case management led to high Service User satisfaction, played an integral role in transforming the lives of people with complex needs, and lowered repeat requests for service. A large longitudinal quantitative study revealed that more time spent with participants substantially decreased the number of repeat requests for service; and, given that repeat requests for service can be an indicator of entrenched poverty, not accessing further services is likely to suggest improvement. The interviews identified the main strengths of ER to be the rapid response and flexible use of funds to stabilise crisis situations and connect people to other supports through strong local networks. Service Users trusted the system because of these strengths, and ER was often an access point to holistic support. There were three main weaknesses identified. First, funding contracts were too short and did not cover the full costs of the program—in particular, case management for complex cases. Second, many Service Users were dependent on ER which was inconsistent with the definition and intent of the program. Third, there was inconsistency in the level of service received by Service Users in different geographic locations. These weaknesses can be improved upon with a joined-up approach featuring co-design and collaborative governance, leading to the successful commissioning of social services. The survey confirmed that volunteers were significant for ER, making up 92% of all workers and 51% of all hours worked in respondent ER programs. Of the 122 respondents, volunteers amounted to 554 full-time equivalents, a contribution valued at $39.4 million. In total there were 8,316 volunteers working in the 122 respondent ER programs. The sector can support and upskill these volunteers (and employees in addition) by developing scalable training solutions such as online training modules, updating ER service standards, and engaging in collaborative learning arrangements where large and small ER Providers share resources. More engagement with peak bodies such as Volunteering Australia might also assist the sector to improve the focus on volunteer engagement. Integrated services achieve better outcomes for complex ER cases—97% of survey respondents either agreed or strongly agreed this was the case. The research identified the dimensions of service integration most relevant to ER Providers to be case management, referrals, the breadth of services offered internally, co-location with interrelated service providers, an established network of support, workforce capability, and Service User engagement. Providers can individually focus on increasing the level of service integration for their ER program to improve their ability to deal with complex cases, which are clearly on the rise. At the system level, a more joined-up approach can also improve service integration across Australia. The key dimensions of this finding are discussed next in more detail. Case management is key for achieving Service User outcomes for complex cases—89% of survey respondents either agreed or strongly agreed this was the case. Interviewees most frequently said they would provide more case management if they could change their service model. Case management allows for more time spent with the Service User, follow up with referral partners, and a higher level of expertise in service delivery to support complex cases. Of course, it is a costly model and not currently funded for all Service Users through ER. Where case management is not available as part of ER, it might be available through a related service that is part of a network of support. Where possible, ER Providers should facilitate access to case management for Service Users who would benefit. At a system level, ER models with a greater component of case management could be implemented as test cases. Referral systems are also key for achieving Service User outcomes, which is reflected in the ER Program Logic presented on page 31. The survey and interview data show that referrals within an integrated service (internal) or in a service hub (co-located) are most effective. Where this is not possible, warm referrals within a trusted network of support are more effective than cold referrals leading to higher take-up and beneficial Service User outcomes. However, cold referrals are most common, pointing to a weakness in ER referral systems. This is because ER Providers do not operate or co-locate with interrelated services in many cases, nor do they have the case management capacity to provide warm referrals in many other cases. For mental illness support, which interviewees identified as one of the most difficult issues to deal with, ER Providers offer an integrated service only 23% of the time, warm referrals 34% of the time, and cold referrals 43% of the time. A focus on referral systems at the individual ER Provider level, and system level through a joined-up approach, might lead to better outcomes for Service Users. The program logic and theory of change for ER have been documented with input from the research findings and included in Section 4.3 on page 31. These show that ER helps people facing a financial crisis to meet their immediate needs, avoid further harm, and access a path to recovery. The research demonstrates that ER is fundamental to supporting vulnerable people in Australia and should therefore continue to be funded by government.

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Seginer, Ido, Louis D. Albright e Robert W. Langhans. On-line Fault Detection and Diagnosis for Greenhouse Environmental Control. United States Department of Agriculture, febbraio 2001. http://dx.doi.org/10.32747/2001.7575271.bard.

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Background Early detection and identification of faulty greenhouse operation is essential, if losses are to be minimized by taking immediate corrective actions. Automatic detection and identification would also free the greenhouse manager to tend to his other business. Original objectives The general objective was to develop a method, or methods, for the detection, identification and accommodation of faults in the greenhouse. More specific objectives were as follows: 1. Develop accurate systems models, which will enable the detection of small deviations from normal behavior (of sensors, control, structure and crop). 2. Using these models, develop algorithms for an early detection of deviations from the normal. 3. Develop identifying procedures for the most important faults. 4. Develop accommodation procedures while awaiting a repair. The Technion team focused on the shoot environment and the Cornell University team focused on the root environment. Achievements Models: Accurate models were developed for both shoot and root environment in the greenhouse, utilizing neural networks, sometimes combined with robust physical models (hybrid models). Suitable adaptation methods were also successfully developed. The accuracy was sufficient to allow detection of frequently occurring sensor and equipment faults from common measurements. A large data base, covering a wide range of weather conditions, is required for best results. This data base can be created from in-situ routine measurements. Detection and isolation: A robust detection and isolation (formerly referred to as 'identification') method has been developed, which is capable of separating the effect of faults from model inaccuracies and disturbance effects. Sensor and equipment faults: Good detection capabilities have been demonstrated for sensor and equipment failures in both the shoot and root environment. Water stress detection: An excitation method of the shoot environment has been developed, which successfully detected water stress, as soon as the transpiration rate dropped from its normal level. Due to unavailability of suitable monitoring equipment for the root environment, crop faults could not be detected from measurements in the root zone. Dust: The effect of screen clogging by dust has been quantified. Implications Sensor and equipment fault detection and isolation is at a stage where it could be introduced into well equipped and maintained commercial greenhouses on a trial basis. Detection of crop problems requires further work. Dr. Peleg was primarily responsible for developing and implementing the innovative data analysis tools. The cooperation was particularly enhanced by Dr. Peleg's three summer sabbaticals at the ARS, Northem Plains Agricultural Research Laboratory, in Sidney, Montana. Switching from multi-band to hyperspectral remote sensing technology during the last 2 years of the project was advantageous by expanding the scope of detected plant growth attributes e.g. Yield, Leaf Nitrate, Biomass and Sugar Content of sugar beets. However, it disrupted the continuity of the project which was originally planned on a 2 year crop rotation cycle of sugar beets and multiple crops (com and wheat), as commonly planted in eastern Montana. Consequently, at the end of the second year we submitted a continuation BARD proposal which was turned down for funding. This severely hampered our ability to validate our findings as originally planned in a 4-year crop rotation cycle. Thankfully, BARD consented to our request for a one year extension of the project without additional funding. This enabled us to develop most of the methodology for implementing and running the hyperspectral remote sensing system and develop the new analytical tools for solving the non-repeatability problem and analyzing the huge hyperspectral image cube datasets. However, without validation of these tools over a ful14-year crop rotation cycle this project shall remain essentially unfinished. Should the findings of this report prompt the BARD management to encourage us to resubmit our continuation research proposal, we shall be happy to do so.

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Perera, Duminda, Ousmane Seidou, Jetal Agnihotri, Mohamed Rasmy, Vladimir Smakhtin, Paulin Coulibaly e Hamid Mehmood. Flood Early Warning Systems: A Review Of Benefits, Challenges And Prospects. United Nations University Institute for Water, Environment and Health, agosto 2019. http://dx.doi.org/10.53328/mjfq3791.

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Floods are major water-related disasters that affect millions of people resulting in thousands of mortalities and billiondollar losses globally every year. Flood Early Warning Systems (FEWS) - one of the floods risk management measures - are currently operational in many countries. The UN Office for Disaster Risk Reduction recognises their importance and strongly advocates for an increase in their availability under the targets of the Sendai Framework for Disaster Risk Reduction, and Sustainable Development Goals (SDGs). However, despite widespread recognition of the importance of FEWS for disaster risk reduction (DRR), there’s a lack of information on their availability and status around the world, their benefits and costs, challenges and trends associated with their development. This report contributes to bridging these gaps by analyzing the responses to a comprehensive online survey with over 80 questions on various components of FEWS (risk knowledge, monitoring and forecasting, warning dissemination and communication, and response capabilities), investments into FEWS, their operational effectiveness, benefits, and challenges. FEWS were classified as technologically “basic”, “intermediate” and “advanced” depending on the existence and sophistication of FEWS` components such as hydrological data = collection systems, data transfer systems, flood forecasting methods, and early warning communication methods. The survey questionnaire was distributed to flood forecasting and warning centers around the globe; the primary focus was developing and least-developed countries (LDCs). The questionnaire is available here: https://inweh.unu.edu/questionnaireevaluation-of-flood-early-warning-systems/ and can be useful in its own right for similar studies at national or regional scales, in its current form or with case-specific modifications. Survey responses were received from 47 developing (including LDCs) and six developed countries. Additional information for some countries was extracted from available literature. Analysis of these data suggests the existence of an equal number of “intermediate” and “advanced” FEWS in surveyed river basins. While developing countries overall appear to progress well in FEWS implementation, LDCs are still lagging behind since most of them have “basic” FEWS. The difference between types of operational systems in developing and developed countries appear to be insignificant; presence of basic, intermediate or advanced FEWS depends on available investments for system developments and continuous financing for their operations, and there is evidence of more financial support — on the order of USD 100 million — to FEWS in developing countries thanks to international aid. However, training the staff and maintaining the FEWS for long-term operations are challenging. About 75% of responses indicate that river basins have inadequate hydrological network coverage and back-up equipment. Almost half of the responders indicated that their models are not advanced and accurate enough to produce reliable forecasts. Lack of technical expertise and limited skilled manpower to perform forecasts was cited by 50% of respondents. The primary reason for establishing FEWS, based on the survey, is to avoid property damage; minimizing causalities and agricultural losses appear to be secondary reasons. The range of the community benefited by FEWS varies, but 55% of FEWS operate in the range between 100,000 to 1 million of population. The number of flood disasters and their causalities has declined since the year 2000, while 50% of currently operating FEWS were established over the same period. This decline may be attributed to the combined DRR efforts, of which FEWS are an integral part. In lower-middle-income and low-income countries, economic losses due to flood disasters may be smaller in absolute terms, but they represent a higher percentage of such countries’ GDP. In high-income countries, higher flood-related losses accounted for a small percentage of their GDP. To improve global knowledge on FEWS status and implementation in the context of Sendai Framework and SDGs, the report’s recommendations include: i) coordinate global investments in FEWS development and standardise investment reporting; ii) establish an international hub to monitor the status of FEWS in collaboration with the national responsible agencies. This will support the sharing of FEWS-related information for accelerated global progress in DRR; iii) develop a comprehensive, index-based ranking system for FEWS according to their effectiveness in flood disaster mitigation. This will provide clear standards and a roadmap for improving FEWS’ effectiveness, and iv) improve coordination between institutions responsible for flood forecasting and those responsible for communicating warnings and community preparedness and awareness.

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Semerikov, Serhiy, Hanna Kucherova, Vita Los e Dmytro Ocheretin. Neural Network Analytics and Forecasting the Country's Business Climate in Conditions of the Coronavirus Disease (COVID-19). CEUR Workshop Proceedings, aprile 2021. http://dx.doi.org/10.31812//123456789/4364.

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The prospects for doing business in countries are also determined by the business confidence index. The purpose of the article is to model trends in indicators that determine the state of the business climate of countries, in particular, the period of influence of the consequences of COVID-19 is of scientific interest. The approach is based on the preliminary results of substantiating a set of indicators and applying the taxonomy method to substantiate an alternative indicator of the business climate, the advantage of which is its advanced nature. The most significant factors influencing the business climate index were identified, in particular, the annual GDP growth rate and the volume of retail sales. The similarity of the trends in the calculated and actual business climate index was obtained, the forecast values were calculated with an accuracy of 89.38%. And also, the obtained modeling results were developed by means of building and using neural networks with learning capabilities, which makes it possible to improve the quality and accuracy of the business climate index forecast up to 96.22%. It has been established that the consequences of the impact of COVID-19 are forecasting a decrease in the level of the country's business climate index in the 3rd quarter of 2020. The proposed approach to modeling the country's business climate is unified, easily applied to the macroeconomic data of various countries, demonstrates a high level of accuracy and quality of forecasting. The prospects for further research are modeling the business climate of the countries of the world in order to compare trends and levels, as well as their changes under the influence of quarantine restrictions.

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Tanksley, Steven D., e Dani Zamir. Development and Testing of a Method for the Systematic Discovery and Utilization of Novel QTLs in the Production of Improved Crop Varieties: Tomato as a Model System. United States Department of Agriculture, giugno 1995. http://dx.doi.org/10.32747/1995.7570570.bard.

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Modern cultivated varieties carry only a small fraction of the variation present in the gene pool. The narrow genetic basis of modern crop plants is a result of genetic bottlenecks imposed during early domestication and modern plant breeding. The wild ancestors of most crop plants can still be found in their natural habitats and Germplasm Centers have been established to collect and maintain this material. These wild and unadapted resources can potentially fuel crop plant improvement efforts for many years into the future (Tanksley and McCouch 1997). Unfortunately, scientists have been unable to exploit the majority of the genetic potential warehoused in germplasm repositories. This is especially true as regards to the improvement of quantitative traits like yield and quality. One of the major problems is that much of the wild germplasm is inferior to modern cultivars for many of the quantitative traits that breeders would like to improve. Our research, focusing on the tomato as a model system, has shown that despite their inferior phenotypes, wild species are likely to contain QTLs that can substantially increase the yield and quality of elite cultivars (de Vicente and Tanksley 1992, Eshed and Zamir 1994, Eshed et al. 1996). Using novel population structures of introgression lines (ILs; Eshed and Zamir 1995) and advanced backcross lines (AB; Tanksley et al. 1996) we identified and introduced valuable QTLs from unadapted germplasm into elite processing tomato varieties. Populations involving crosses with five Lycopersicon species (L. pennellii (Eshed and Zamir 1994; Eshed et al. 1996; Eshed and Zamir 1996), L. hirsutum (Bernacchi et al. 1998), L. pimpinellifolium (Tanksley et al. 1996), L. parviflorum (unpub.), L. peruvianum (Fulton et al. 1997) have been field and laboratory tested in a number of locations around the world. QTLs from the wild parent were identified that improve one or more of the key quantitative traits for processing tomatoes (yield, brix, sugar and acid composition and earliness) by as much as 10-30%. Nearly isogenic lines (QTL-NILs) have been generated for a subset of these QTLs. Each QTL-NIL contains the entire genome of the elite cultivated parent except for a segment (5-40 cM) of the wild species genome corresponding to a specific QTL. The genetic material and information that was developed in this program is presently used by American and Israeli seed companies for the breeding of superior varieties. We expect that in the next few years these varieties will make a difference in the marketplace.

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Hart, Tim, Mary Wickenden, Stephen Thompson, Yul Derek Davids, Gary Pienaar, Mercy Ngungu, Yamkela Majikijela et al. Socio-Economic Wellbeing and Human Rights-Related Experiences of People with Disabilities in Covid-19 Times in South Africa. Institute of Development Studies (IDS), gennaio 2022. http://dx.doi.org/10.19088/ids.2022.013.

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During the early months of the global pandemic the international Disability Rights Monitor group survey illustrated the circumstances of persons with disabilities around the world. Gradually literature on the situation for persons with disabilities in sub-Saharan Africa started to emerge. As members of an informal network looking at issues affecting this group, some of the authors of this report realised that much of the research done was not specifically focusing on their perceptions during the pandemic and that it was not using the WG-SS questions. Having noticed a gap in the type of data being collected by other scholars and the media, this small informal network identified a need for a survey that would look at both experiences and perceptions of persons with disabilities focussing on lived experiences of socioeconomic impacts and access to human rights during the pandemic in South Africa. This report summarises some of the key findings of the study, which was conducted on-line using Google Forms from the 1 July to 31 August 2021. All percentages displayed are rounded to the nearest percent and this may affect what is displayed in charts. While we cite some literature in this report, a separate literature review was written by the team, and was used to guide the research and focus the questions.

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