46 resultados para Computer and network security
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This paper proposes strategies to reduce the number of variables and the combinatorial search space of the multistage transmission expansion planning problem (TEP). The concept of the binary numeral system (BNS) is used to reduce the number of binary and continuous variables related to the candidate transmission lines and network constraints that are connected with them. The construction phase of greedy randomized adaptive search procedure (GRASP-CP) and additional constraints, obtained from power flow equilibrium in an electric power system are employed for more reduction in search space. The multistage TEP problem is modeled like a mixed binary linear programming problem and solved using a commercial solver with a low computational time. The results of one test system and two real systems are presented in order to show the efficiency of the proposed solution technique. © 1969-2012 IEEE.
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Biogeographical systems can be analyzed as networks of species and geographical units. Within such a biogeographical network, individual species may differ fundamentally in their linkage pattern, and therefore hold different topological roles. To advance our understanding of the relationship between species traits and large-scale species distribution patterns in archipelagos, we use a network approach to classify birds as one of four biogeographical species roles: peripherals, connectors, module hubs, and network hubs. These roles are based upon the position of species within the modular network of islands and species in Wallacea and the West Indies. We test whether species traits - including habitat requirements, altitudinal range-span, feeding guild, trophic level, and body length - correlate with species roles. In both archipelagos, habitat requirements, altitudinal range-span and body length show strong relations to species roles. In particular, species that occupy coastal- and open habitats, as well as habitat generalists, show higher proportions of connectors and network hubs and thus tend to span several biogeographical modules (i.e. subregions). Likewise, large body size and a wide altitudinal range-span are related to a wide distribution on many islands and across several biogeographical modules. On the other hand, species restricted to interior forest are mainly characterized as peripherals and, thus, have narrow and localized distributions within biogeographical modules rather than across the archipelago-wide network. These results suggest that the ecological amplitude of a species is highly related to its geographical distribution within and across bio geographical subregions and furthermore supports the idea that large-scale species distributions relate to distributions at the local community level. We finally discuss how our biogeographical species roles may correspond to the stages of the taxon cycle and other prominent theories of species assembly. © 2013 The Authors.
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Pós-graduação em Engenharia Elétrica - FEIS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC
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Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC
SW-V: modelo de streaming de software baseado em técnicas de virtualização e transporte peer-to-peer
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Pós-graduação em Ciência da Computação - IBILCE
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Focus groups are seen as important tools in qualitative research for evaluating projects aimed at articulating social networks and movements. Six focus groups were held as one of the stages in research as part of the Food Safety and Sustainable Nutrition Project (SANS). This social network articulates the academic world with social movements and government in defense of the human right to suitable nutrition. This report is aimed at discussing the experience of applying focus groups to the investigation of perceptions by health professionals of activities related to food and nutrition in basic health care. These groups made it possible to bring together 52 professionals from 13 municipalities in the State of São Paulo, Brazil, and they exchanged experiences and debated issues related to food safety in the area of health care. The group discussions identified eating, nutrition vigilance and intersectoriality as emerging topics. The focus group technique proved to be a suitable tool for investigating the topic quickly and in depth, with a large number of professionals working in different contexts. In fact, the discussions went beyond the objectives of the research, since the group work made it possible to strengthen the process of articulation carried out by a network that promoting local measures in food safety and sustainable nutrition.
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Chemoreception is among the most important sensory modalities in animals. Organisms use the ability to perceive chemical compounds in all major ecological activities. Recent studies have allowed the characterization of chemoreceptor gene families. These genes present strikingly high variability in copy numbers and pseudogenization degrees among different species, but the mechanisms underlying their evolution are not fully understood. We have analyzed the functional networks of these genes, their orthologs distribution, and performed phylogenetic analyses in order to investigate their evolutionary dynamics. We have modeled the chemosensory networks and compared the evolutionary constraints of their genes in Mus musculus, Homo sapiens, and Rattus norvegicus. We have observed significant differences regarding the constraints on the orthologous groups and network topologies of chemoreceptors and signal transduction machinery. Our findings suggest that chemosensory receptor genes are less constrained than their signal transducing machinery, resulting in greater receptor diversity and conservation of information processing pathways. More importantly, we have observed significant differences among the receptors themselves, suggesting that olfactory and bitter taste receptors are more conserved than vomeronasal receptors.
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Internet access by wireless networks has grown considerably in recent years. However, these networks are vulnerable to security problems, especially those related to denial of service attacks. Intrusion Detection Systems(IDS)are widely used to improve network security, but comparison among the several existing approaches is not a trivial task. This paper proposes building a datasetfor evaluating IDS in wireless environments. The data were captured in a real, operating network. We conducted tests using traditional IDS and achieved great results, which showed the effectiveness of our proposed approach.
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Wireless communications is a feature that has become indispensable for many people in the whole world. Through this feature, communication process can become much more efficient, allowing people to access information much more quickly wherever they are. The constant evolution of communication technologies allows the development of new unthinkable applications and services. This new range of possibilities brings greater mobility and efficiency for final users and also helps service providers and carriers to improve the quality of services offered by them. This study presents the principles of wireless communication and the Wi-Fi technology as well as its most modern applications, covering from the basics of computer networks to the procedures of planning a wireless network, concepts of radio frequency, antennas, patterns, regulatory agencies, network equipment, protocols and network monitoring
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To analyse the associations between high screen time and overweight, poor dietary habits and physical activity in adolescents according to sex. The study comprised 515 boys and 716 girls aged 14-17 years from Londrina, Brazil. Nutritional status (normal weight or overweight/obese) was assessed by calculating the body mass index. Eating habits and time spent in physical activity were reported using a questionnaire. The measurement of screen time considered the time spent watching television, using a computer and playing video games during a normal week. Associations between high screen time and dependent variables (nutritional status, eating habits and physical activity levels) were assessed by binary logistic regression, adjusted for sociodemographic and lifestyle variables. Most adolescents (93.8% of boys and 87.2% of girls) spent more than 2 hours per day in screen-time activities. After adjustments, an increasing trend in the prevalence of overweight and physical inactivity with increasing time spent on screen activities was observed for both sexes. Screen times of >4 hours/day compared with <2 hours/day were associated with physical inactivity, low consumption of vegetables and high consumption of sweets only in girls and the consumption of soft drinks in both sexes. The frequency of overweight and physical inactivity increased with increasing screen time in a trending manner and independently of the main confounders. The relationship between high screen time and poor eating habits was particularly relevant for adolescent girls.
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Networked control systems (NCSs) are distributed control systems in which the sensors, actuators, and controllers are physically separated and connected through an industrial network. The main challenge related to the development of NCSs is the degenerative effects caused by the inclusion of this communication network in the closed loop control. In order to mitigate these effects, co-simulation tools for NCS have been developed to study the network influence in the NCS. This paper presents a revision about co-simulation tools for NCS and the application of two of these tools for the design and evaluation of NCSs. The TrueTime and Jitterbug tools were used together to evaluate the main configuration parameter that affects the performance of CAN-based NCS and to verify the NCS quality of control under various timing conditions including different transmission period of messages and network delays. Therefore, the simulation results led to the conclusion that despite the transmission period of messages is the most significant factor among the analyzed in the design of NCS, its influence is related to the kind of system with greater effects in NCSs with fast dynamics.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)