896 resultados para Android,Peer to Peer,Wifi,Mesh Network
Resumo:
Understanding how decisions for international investments are made and how this affects the overall pattern of investments and firm’s performance is of particular importance both in strategy and international business research. This dissertation introduced first home-host country relatedness (HHCR) as the degree to which countries are efficiently combined within the investment portfolios of firms. It theorized and demonstrated that HHCR will vary with the motivation for investments along at least two key dimensions: the nature of foreign investments and the connectedness of potential host countries to the rest of the world. Drawing on cognitive psychology and decision-making research, it developed a theory of strategic decision making proposing that strategic solutions are chosen close to a convenient anchor. Building on research on memory imprinting, it also proposed that managers tend to rely on older knowledge representation. In the context of international investment decisions, managers use their home countries as an anchor and are more likely to choose as a site for foreign investments host countries that are ‘close’ to the home country. These decisions are also likely to rely more strongly on closeness to time invariant country factors of historic and geographic nature rather than time-variant institutions. Empirical tests using comprehensive investments data by all public multinational companies (MNC) worldwide, or over 15,000 MNCs with over half a million subsidiaries, support the claims. Finally, the dissertation introduced the concept of International Coherence (IC) defined as the degree to which an MNE’s network comprises countries that are related. It was hypothesized that maintaining a high level of coherence is important for firm performance and will enhance it. Also, the presence of international coherence mitigates some of the negative effects of unrelated product diversification. Empirical tests using data on foreign investments of over 20,000 public firms, while also developing a home-host country relatedness index for up to 24,300 home-host pairs, provided support for the theory advanced.
Resumo:
Developing analytical models that can accurately describe behaviors of Internet-scale networks is difficult. This is due, in part, to the heterogeneous structure, immense size and rapidly changing properties of today's networks. The lack of analytical models makes large-scale network simulation an indispensable tool for studying immense networks. However, large-scale network simulation has not been commonly used to study networks of Internet-scale. This can be attributed to three factors: 1) current large-scale network simulators are geared towards simulation research and not network research, 2) the memory required to execute an Internet-scale model is exorbitant, and 3) large-scale network models are difficult to validate. This dissertation tackles each of these problems. ^ First, this work presents a method for automatically enabling real-time interaction, monitoring, and control of large-scale network models. Network researchers need tools that allow them to focus on creating realistic models and conducting experiments. However, this should not increase the complexity of developing a large-scale network simulator. This work presents a systematic approach to separating the concerns of running large-scale network models on parallel computers and the user facing concerns of configuring and interacting with large-scale network models. ^ Second, this work deals with reducing memory consumption of network models. As network models become larger, so does the amount of memory needed to simulate them. This work presents a comprehensive approach to exploiting structural duplications in network models to dramatically reduce the memory required to execute large-scale network experiments. ^ Lastly, this work addresses the issue of validating large-scale simulations by integrating real protocols and applications into the simulation. With an emulation extension, a network simulator operating in real-time can run together with real-world distributed applications and services. As such, real-time network simulation not only alleviates the burden of developing separate models for applications in simulation, but as real systems are included in the network model, it also increases the confidence level of network simulation. This work presents a scalable and flexible framework to integrate real-world applications with real-time simulation.^
Resumo:
The lack of analytical models that can accurately describe large-scale networked systems makes empirical experimentation indispensable for understanding complex behaviors. Research on network testbeds for testing network protocols and distributed services, including physical, emulated, and federated testbeds, has made steady progress. Although the success of these testbeds is undeniable, they fail to provide: 1) scalability, for handling large-scale networks with hundreds or thousands of hosts and routers organized in different scenarios, 2) flexibility, for testing new protocols or applications in diverse settings, and 3) inter-operability, for combining simulated and real network entities in experiments. This dissertation tackles these issues in three different dimensions. First, we present SVEET, a system that enables inter-operability between real and simulated hosts. In order to increase the scalability of networks under study, SVEET enables time-dilated synchronization between real hosts and the discrete-event simulator. Realistic TCP congestion control algorithms are implemented in the simulator to allow seamless interactions between real and simulated hosts. SVEET is validated via extensive experiments and its capabilities are assessed through case studies involving real applications. Second, we present PrimoGENI, a system that allows a distributed discrete-event simulator, running in real-time, to interact with real network entities in a federated environment. PrimoGENI greatly enhances the flexibility of network experiments, through which a great variety of network conditions can be reproduced to examine what-if questions. Furthermore, PrimoGENI performs resource management functions, on behalf of the user, for instantiating network experiments on shared infrastructures. Finally, to further increase the scalability of network testbeds to handle large-scale high-capacity networks, we present a novel symbiotic simulation approach. We present SymbioSim, a testbed for large-scale network experimentation where a high-performance simulation system closely cooperates with an emulation system in a mutually beneficial way. On the one hand, the simulation system benefits from incorporating the traffic metadata from real applications in the emulation system to reproduce the realistic traffic conditions. On the other hand, the emulation system benefits from receiving the continuous updates from the simulation system to calibrate the traffic between real applications. Specific techniques that support the symbiotic approach include: 1) a model downscaling scheme that can significantly reduce the complexity of the large-scale simulation model, resulting in an efficient emulation system for modulating the high-capacity network traffic between real applications; 2) a queuing network model for the downscaled emulation system to accurately represent the network effects of the simulated traffic; and 3) techniques for reducing the synchronization overhead between the simulation and emulation systems.
Resumo:
With the developments in computing and communication technologies, wireless sensor networks have become popular in wide range of application areas such as health, military, environment and habitant monitoring. Moreover, wireless acoustic sensor networks have been widely used for target tracking applications due to their passive nature, reliability and low cost. Traditionally, acoustic sensor arrays built in linear, circular or other regular shapes are used for tracking acoustic sources. The maintaining of relative geometry of the acoustic sensors in the array is vital for accurate target tracking, which greatly reduces the flexibility of the sensor network. To overcome this limitation, we propose using only a single acoustic sensor at each sensor node. This design greatly improves the flexibility of the sensor network and makes it possible to deploy the sensor network in remote or hostile regions through air-drop or other stealth approaches. Acoustic arrays are capable of performing the target localization or generating the bearing estimations on their own. However, with only a single acoustic sensor, the sensor nodes will not be able to generate such measurements. Thus, self-organization of sensor nodes into virtual arrays to perform the target localization is essential. We developed an energy-efficient and distributed self-organization algorithm for target tracking using wireless acoustic sensor networks. The major error sources of the localization process were studied, and an energy-aware node selection criterion was developed to minimize the target localization errors. Using this node selection criterion, the self-organization algorithm selects a near-optimal localization sensor group to minimize the target tracking errors. In addition, a message passing protocol was developed to implement the self-organization algorithm in a distributed manner. In order to achieve extended sensor network lifetime, energy conservation was incorporated into the self-organization algorithm by incorporating a sleep-wakeup management mechanism with a novel cross layer adaptive wakeup probability adjustment scheme. The simulation results confirm that the developed self-organization algorithm provides satisfactory target tracking performance. Moreover, the energy saving analysis confirms the effectiveness of the cross layer power management scheme in achieving extended sensor network lifetime without degrading the target tracking performance.
Resumo:
An important issue of resource distribution is the fairness of the distribution. For example, computer network management wishes to distribute network resource fairly to its users. To describe the fairness of the resource distribution, a quantitative fairness score function was proposed in 1984 by Jain et al. The purpose of this paper is to propose a modified network sharing fairness function so that the users can be treated differently according to their priority levels. The mathematical properties are discussed. The proposed fairness score function keeps all the nice properties of and provides better performance when the network users have different priority levels.
Resumo:
Biological detectors, such as canines, are valuable tools used for the rapid identification of illicit materials. However, recent increased scrutiny over the reliability, field accuracy, and the capabilities of each detection canine is currently being evaluated in the legal system. For example, the Supreme Court case, State of Florida v. Harris, discussed the need for continuous monitoring of canine abilities, thresholds, and search capabilities. As a result, the fallibility of canines for detection was brought to light, as well as a need for further research and understanding of canine detection. This study is two-fold, as it looks to not only create new training aids for canines that can be manipulated for dissipation control, but also investigates canine field accuracy to objects with similar odors to illicit materials. It was the goal of this research to improve upon current canine training aid mimics. Sol-gel polymer training aids, imprinted with the active odor of cocaine, were developed. This novel training aid improved upon the longevity of currently existing training aids, while also provided a way to manipulate the polymer network to alter the dissipation rate of the imprinted active odors. The manipulation of the polymer network could allow handlers to control the abundance of odors presented to their canines, familiarizing themselves to their canine’s capabilities and thresholds, thereby increasing the canines’ strength in court. The field accuracy of detection canines was recently called into question during the Supreme Court case, State of Florida v. Jardines, where it was argued that if cocaine’s active odor, methyl benzoate, was found to be produced by the popular landscaping flower, snapdragons, canines will false alert to said flowers. Therefore, snapdragon flowers were grown and tested both in the laboratory and in the field to determine the odors produced by snapdragon flowers; the persistence of these odors once flowers have been cut; and whether detection canines will alert to both growing and cut flowers during a blind search scenario. Results revealed that although methyl benzoate is produced by snapdragon flowers, certified narcotics detection canines can distinguish cocaine’s odor profile from that of snapdragon flowers and will not alert.
Resumo:
With the developments in computing and communication technologies, wireless sensor networks have become popular in wide range of application areas such as health, military, environment and habitant monitoring. Moreover, wireless acoustic sensor networks have been widely used for target tracking applications due to their passive nature, reliability and low cost. Traditionally, acoustic sensor arrays built in linear, circular or other regular shapes are used for tracking acoustic sources. The maintaining of relative geometry of the acoustic sensors in the array is vital for accurate target tracking, which greatly reduces the flexibility of the sensor network. To overcome this limitation, we propose using only a single acoustic sensor at each sensor node. This design greatly improves the flexibility of the sensor network and makes it possible to deploy the sensor network in remote or hostile regions through air-drop or other stealth approaches. Acoustic arrays are capable of performing the target localization or generating the bearing estimations on their own. However, with only a single acoustic sensor, the sensor nodes will not be able to generate such measurements. Thus, self-organization of sensor nodes into virtual arrays to perform the target localization is essential. We developed an energy-efficient and distributed self-organization algorithm for target tracking using wireless acoustic sensor networks. The major error sources of the localization process were studied, and an energy-aware node selection criterion was developed to minimize the target localization errors. Using this node selection criterion, the self-organization algorithm selects a near-optimal localization sensor group to minimize the target tracking errors. In addition, a message passing protocol was developed to implement the self-organization algorithm in a distributed manner. In order to achieve extended sensor network lifetime, energy conservation was incorporated into the self-organization algorithm by incorporating a sleep-wakeup management mechanism with a novel cross layer adaptive wakeup probability adjustment scheme. The simulation results confirm that the developed self-organization algorithm provides satisfactory target tracking performance. Moreover, the energy saving analysis confirms the effectiveness of the cross layer power management scheme in achieving extended sensor network lifetime without degrading the target tracking performance.
Resumo:
Traffic incidents are a major source of traffic congestion on freeways. Freeway traffic diversion using pre-planned alternate routes has been used as a strategy to reduce traffic delays due to major traffic incidents. However, it is not always beneficial to divert traffic when an incident occurs. Route diversion may adversely impact traffic on the alternate routes and may not result in an overall benefit. This dissertation research attempts to apply Artificial Neural Network (ANN) and Support Vector Regression (SVR) techniques to predict the percent of delay reduction from route diversion to help determine whether traffic should be diverted under given conditions. The DYNASMART-P mesoscopic traffic simulation model was applied to generate simulated data that were used to develop the ANN and SVR models. A sample network that comes with the DYNASMART-P package was used as the base simulation network. A combination of different levels of incident duration, capacity lost, percent of drivers diverted, VMS (variable message sign) messaging duration, and network congestion was simulated to represent different incident scenarios. The resulting percent of delay reduction, average speed, and queue length from each scenario were extracted from the simulation output. The ANN and SVR models were then calibrated for percent of delay reduction as a function of all of the simulated input and output variables. The results show that both the calibrated ANN and SVR models, when applied to the same location used to generate the calibration data, were able to predict delay reduction with a relatively high accuracy in terms of mean square error (MSE) and regression correlation. It was also found that the performance of the ANN model was superior to that of the SVR model. Likewise, when the models were applied to a new location, only the ANN model could produce comparatively good delay reduction predictions under high network congestion level.
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The National Police for Basic Care (PNAB), regulated by ordinance nº2488 from October 2011, restates the Family Health Strategy (ESF) as a priority to the expansion, consolidation and qualification of basic attention to health matters in Brazil. In order to bring it about, city counsellors along with other federal entities ought to ordinate their work process deepening principals, directions and fundaments of Basic Care (AB). Besides ESF, the new PNAB expatiates on the Family Health Support Centres (NASF), reaffirming their role on broadening the scope of basic care actions and their improvements, ratifying their ability to share knowledge and support Basic Care professionals. All this considered, the purpose of this work is to investigate how NASF is currently structured in João Pessoa and what has been achieved by it on what concerns to mental health. Its main objectives are to analyse the practices of mental health professionals that are part of NASF teams and if they differ from what has been developed by the other members of the teams; to discuss the articulation of NASF in managing mental health measures on what concerns to internal organisatio n and to the city health network; to identify strategies used to organise such measures on mental health in Basic Care. To reach such goals, individual interviews have taken place two city health managers and four of NASF professionals that participated on the Mental Health Office as representatives of their sanitary districts. Also a focal group formed by various supporters of NASF was created, contemplating the diversity of professional categories involved with the teams and sanitary districts. It was possible to identify in NASF, in João Pessoa, an organisation based by the matrix support in which both management and basic care demands reflect a series of actions developed alongside with ESF. Amongst such actions, matrixing, home visits and the Singular Therapeutic Project (PTS) stand out. These activities have been discussed on the focal group and integrate the daily work of all NASF supporters despite their professional categories. NASF presents itself as a powerful strategy to SUS proper qualification and support to strengthen Basic Care and broaden family health teams‟actions.
Resumo:
The main objective of this work was to enable the recognition of human gestures through the development of a computer program. The program created captures the gestures executed by the user through a camera attached to the computer and sends it to the robot command referring to the gesture. They were interpreted in total ve gestures made by human hand. The software (developed in C ++) widely used the computer vision concepts and open source library OpenCV that directly impact the overall e ciency of the control of mobile robots. The computer vision concepts take into account the use of lters to smooth/blur the image noise reduction, color space to better suit the developer's desktop as well as useful information for manipulating digital images. The OpenCV library was essential in creating the project because it was possible to use various functions/procedures for complete control lters, image borders, image area, the geometric center of borders, exchange of color spaces, convex hull and convexity defect, plus all the necessary means for the characterization of imaged features. During the development of the software was the appearance of several problems, as false positives (noise), underperforming the insertion of various lters with sizes oversized masks, as well as problems arising from the choice of color space for processing human skin tones. However, after the development of seven versions of the control software, it was possible to minimize the occurrence of false positives due to a better use of lters combined with a well-dimensioned mask size (tested at run time) all associated with a programming logic that has been perfected over the construction of the seven versions. After all the development is managed software that met the established requirements. After the completion of the control software, it was observed that the overall e ectiveness of the various programs, highlighting in particular the V programs: 84.75 %, with VI: 93.00 % and VII with: 94.67 % showed that the nal program performed well in interpreting gestures, proving that it was possible the mobile robot control through human gestures without the need for external accessories to give it a better mobility and cost savings for maintain such a system. The great merit of the program was to assist capacity in demystifying the man set/machine therefore uses an easy and intuitive interface for control of mobile robots. Another important feature observed is that to control the mobile robot is not necessary to be close to the same, as to control the equipment is necessary to receive only the address that the Robotino passes to the program via network or Wi-Fi.
Resumo:
De nombreux problèmes liés aux domaines du transport, des télécommunications et de la logistique peuvent être modélisés comme des problèmes de conception de réseaux. Le problème classique consiste à transporter un flot (données, personnes, produits, etc.) sur un réseau sous un certain nombre de contraintes dans le but de satisfaire la demande, tout en minimisant les coûts. Dans ce mémoire, on se propose d'étudier le problème de conception de réseaux avec coûts fixes, capacités et un seul produit, qu'on transforme en un problème équivalent à plusieurs produits de façon à améliorer la valeur de la borne inférieure provenant de la relaxation continue du modèle. La méthode que nous présentons pour la résolution de ce problème est une méthode exacte de branch-and-price-and-cut avec une condition d'arrêt, dans laquelle nous exploitons à la fois la méthode de génération de colonnes, la méthode de génération de coupes et l'algorithme de branch-and-bound. Ces méthodes figurent parmi les techniques les plus utilisées en programmation linéaire en nombres entiers. Nous testons notre méthode sur deux groupes d'instances de tailles différentes (gran-des et très grandes), et nous la comparons avec les résultats donnés par CPLEX, un des meilleurs logiciels permettant de résoudre des problèmes d'optimisation mathématique, ainsi qu’avec une méthode de branch-and-cut. Il s'est avéré que notre méthode est prometteuse et peut donner de bons résultats, en particulier pour les instances de très grandes tailles.
Resumo:
This paper presents the first multi vector energy analysis for the interconnected energy systems of Great Britain (GB) and Ireland. Both systems share a common high penetration of wind power, but significantly different security of supply outlooks. Ireland is heavily dependent on gas imports from GB, giving significance to the interconnected aspect of the methodology in addition to the gas and power interactions analysed. A fully realistic unit commitment and economic dispatch model coupled to an energy flow model of the gas supply network is developed. Extreme weather events driving increased domestic gas demand and low wind power output were utilised to increase gas supply network stress. Decreased wind profiles had a larger impact on system security than high domestic gas demand. However, the GB energy system was resilient during high demand periods but gas network stress limited the ramping capability of localised generating units. Additionally, gas system entry node congestion in the Irish system was shown to deliver a 40% increase in short run costs for generators. Gas storage was shown to reduce the impact of high demand driven congestion delivering a reduction in total generation costs of 14% in the period studied and reducing electricity imports from GB, significantly contributing to security of supply.
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[EN]The number of dietary exposure assessment studies focussing on children is very limited. Children are however a vulnerable group due to their higher food consumption level per kg body weight. Therefore, the EXPOCHI project aims [1] to create a relational network of individual food consumption databases in children, covering different geographical areas within Europe, and [2] to use these data to assess the usual intake of lead, chromium, selenium and food colours.
Resumo:
As definições tradicionais de prostituição tendem a enfatizar três aspectos: a existência de uma interacção de tipo sexual, a existência de uma retribuição económica por essa interacção e a existência de indiferença afectiva entre as partes envolvidas, isto é entre cliente e prostituta (Machado & Gonçalves, 2002) O conceito de “rede” tem surgido recentemente nos mais diversos domínios e com inúmeras designações associadas, pelo que pode falar-se de redes em áreas e aplicações tão diversas, pois é usado para “designar uma grande variedade de objectos e de fenómenos”. Os vínculos numa rede primária são, assim, essencialmente de natureza afectiva, não havendo qualquer formalidade na relação. Já as redes secundárias reportam-nos aos membros da nossa rede com os quais estabelecemos relações num contexto formal e com objectivos funcionais (Guadalupe, 2009) Tendo em conta o objecto de estudo, pretende-se com este trabalho de pesquisa, perceber quais as redes de suporte desta população, bem como a eficácia da rede em relação aos vínculos afectivos. Podemos assim apurar que relativamente às redes de suporte primárias estas prostitutas têm mais perto de si os seus companheiros e em seguida os seus filhos, mantendo, 29.4 % uma boa relação com a sua família e uma percentagem igual uma má relação familiar. Relativamente às redes de suporte secundárias, uma parte desta população recorre a politicas sociais activas, implementadas pelo Ministério do Trabalho e da Segurança Social operacionalizadas pela Segurança Social de Coimbra para o apoio social. Ao nível da intervenção social directa, recorrem à Associação Existências para o apoio emocional, psicossocial e de aconselhamento em contexto de gabinete ou em contexto outreach. /
Resumo:
A rede social dos sujeitos tem sido considerada fundamental para lidar com a adversidade. O objetivo central deste estudo foi caracterizar as redes sociais pessoais de jovens em regime de acolhimento institucional prolongado, na perspetiva dos próprios e dos técnicos das instituições e perceber se estas relacionam com o projeto de vida. Participaram 84 jovens, com idades compreendidas entre os 12 e os 20 anos de idade, acolhidos em 6 lares de infância e juventude do distrito de Santarém. Os participantes são na sua maioria do sexo feminino, com uma idade média de 15 anos. Para avaliação das variáveis em estudo utilizou-se a versão revista sumária do Instrumento de Avaliação de Redes Sociais Pessoais (IARSP-RS) e um questionário de autorresposta de caracterização da instituição de acolhimento. Os resultados desta investigação permitiram verificar que as redes dos jovens em situação de acolhimento institucional são fragmentadas, constituídas, em média, por 12 elementos e predominantemente compostas por familiares, amigos e profissionais das instituições, destacando-se as relações familiares. O nível de apoio social percebido é elevado na função emocional e informativa. Verificou-se uma maior reciprocidade do apoio por parte das jovens do sexo feminino, a institucionalização pode potenciar a expansão da rede social de suporte e a frequência de contactos associa-se à distância geográfica. A satisfação dos jovens com o suporte social é elevada. Metade dos jovens perspetivam a saída da instituição pela via da autonomização. A perceção dos profissionais das redes de suporte social é mais limitada, no tamanho, reciprocidade, satisfação com o suporte social e nas relações estabelecidas com a família, amigos da comunidade envolvente e relações de trabalho/estudo. Por outro lado, os técnicos identificam um nível mais elevado de densidade e de vínculos com os técnicos e educadores da instituição. Não se verificaram diferenças significativas nas características da rede social em função do projeto de vida, porém perceberam-se diferenças no projeto de vida em função da idade e da duração do acolhimento. A rede social apresenta um potencial protetor que vale a pena conhecer, fomentar e valorizar, destacando-se que é importante conhecer a perspetiva do próprio sujeito, já que esta tem um carácter muito pessoal. / The social network has been considered fundamental to deal with the adversities. The main objective of this study was to characterize the social network of the youngesters in prolonged institutional care, from the perspective of themselves and professionals of the institutions and to observe if their social network fits with their life project. 84 youngsters with ages between 12 and 20 years old living in 6 institutions of childhood and juvenile care from de district of Santarém participated in this study. The participants are mainly female, with an average age of 15 years old. To evaluate the variables in study, it was applied a version of the summary review of the Instrument of Evaluation of Personal Social Networks (IARSP-RS) and a survey of self-response to characterize the institutional care. The results of this investigation allowed to conclude that the social network of youngsters in a situation of institutional care are fragmented, composed by an average of 12 elements and primarily composed by family members, friends and professionals, but the most significant were the family relationships. It was observed that social support is high in terms of emotional and informative functions. It was observed an higher mutual support from the young ladies, institutionalization may foster the expansion of the social support network and that the frequency of connections is related with geographic distance. The satisfaction of the youngsters with social support is high. Half of the youngsters previews getting out of the institution by becoming autonomous. The understanding of the professionals of the social support network is more limited, about size, mutuality, satisfaction with the social support, family, friends of involving community and relationship of work/study. On the other side, the professionals identify an higher level of density and bonds with the technicals and educators of the institutions. Significative differences in the characteristics social network in terms of the life project weren’t found, however there were diferences in the life project in terms of the age and the duration of institutionalization. The social network has a protector potential that is worth of studying, promote and valorize, highlighting that it is important to know the perspective of the individual, because of its personal nature.