Social networks on the Internet: a practical investigation about file sharing on Facebook

The social networks on the internet have experienced rapid growth and joined millions of users in Brazil and throughout the world. Such networks allow groups of people to communicate and exchange information. Sharing information in files is also a growing activity on the internet and is done in various ways. However, applications are not yet available to enable file sharing on Facebook, the premier social network today. This study aims to investigate how users use Facebook, and their practices for file sharing. Due to the experimental nature of this research, we opted for a data collection survey, applied over the web. From the data analysis, we have found a frequent use of file sharing, but no interest in paid services. As for Facebook, there was an extensive use of applications. The set of results shows a favourable scenario for applications that allow file sharing on Facebook.

Voltage regulator modeling for the three-phase power flow in distribution networks

In this paper a three-phase power flow for electrical distribution systems considering different models of voltage regulators is presented. A voltage regulator (VR) is an equipment that maintains the voltage level in a predefined value in a distribution line in spite of the load variations within its nominal power. Three different types of connections are analyzed: 1) wye-connected regulators, 2) open delta-connected regulators and 3) closed delta-connected regulators. To calculate the power flow, the three-phase backward/forward sweep algorithm is used. The methodology is tested on the IEEE 34 bus distribution system. ©2008 IEEE.

Integrated planning of electric power distribution networks

In this work, a heuristic model for integrated planning of primary distribution network and secondary distribution circuits is proposed. A Tabu Search (TS) algorithm is employed to solve the planning of primary distribution networks. Evolutionary Algorithms (EA) are used to solve the planning model of secondary networks. The planning integration of both networks is carried out by means a constructive heuristic taking into account a set of integration alternatives between these networks. These integration alternatives are treated in a hierarchical way. The planning of primary networks and secondary distribution circuits is carried out based on assessment of the effects of the alternative solutions in the expansion costs of both networks simultaneously. In order to evaluate this methodology, tests were performed for a real-life distribution system taking into account the primary and secondary networks.

On the efficiency of an alternative codification for multiobjective service restoration in electric distribution networks

This paper proposes an alternative codification to solve the service restoration in electric power distribution networks using a SPEA2 multiobjective evolutionary algorithm, assuming the minimization of both the load not supplied and the number of switching operations involved in the restoration plan. Constrains as the line, power source and voltage drop limits in order to avoid the activation of protective devices are all included in the proposed algorithm. Experimental results have shown the convenience on considering these new representations in the sense of feasibility maintenance and also in the sense of better approximation to the Pareto set. ©2009 IEEE.

Distributed generation impact evaluation using a multi-objective tabu search

Distribution networks paradigm is changing currently requiring improved methodologies and tools for network analysis and planning. A relevant issue is analyzing the impact of the Distributed Generation penetration in passive networks considering different operation scenarios. Studying DG optimal siting and sizing the planner can identify the network behavior in presence of DG. Many approaches for the optimal DG allocation problem successfully used multi-objective optimization techniques. So this paper contributes to the fundamental stage of multi-objective optimization of finding the Pareto optimal solutions set. It is proposed the application of a Multi-objective Tabu Search and it was verified a better performance comparing to the NSGA-II method. © 2009 IEEE.

Proposal of a hybrid rectifier structure with HPF and low THD suitable for front-end trolleybuses systems supplied by AC distribution networks

This paper presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. The proposed structure is composed by an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of composing the input line current waveform assuring high power factor (HPF) and low THDI, as well as ordinary front-end converter. However, the power rating of the switched converter is about 34% of the total output power, assuring robustness and reliability. Therefore, the proposed structure was named single-phase HPF hybrid rectifier. A prototype rated at 15kW was developed and analyzed in laboratory. It was found that the input line current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, the PWM control strategy, and experimental results are also presented in this paper. © 2009 IEEE.

Optimal contract pricing of distributed generation under a competitive framework

A bilevel programming approach for the optimal contract pricing of distributed generation (DG) in distribution networks is presented. The outer optimization problem corresponds to the owner of the DG who must decide the contract price that would maximize his profits. The inner optimization problem corresponds to the distribution company (DisCo), which procures the minimization of the payments incurred in attending the expected demand while satisfying network constraints. The meet the expected demand the DisCo can purchase energy either form the transmission network through the substations or form the DG units within its network. The inner optimization problem is substituted by its Karush- Kuhn-Tucker optimality conditions, turning the bilevel programming problem into an equivalent single-level nonlinear programming problem which is solved using commercially available software. © 2010 IEEE.

Trolleybus power system for operation with AC or DC distribution networks

This paper presents the development and experimental analysis of a special input stage converter for a Trolleybus type vehicle allowing its operation in AC (two wires, single-phase) or DC distribution networks. The architecture of proposed input stage converter is composed by five interleaved boost rectifiers operating in discontinuous conduction mode. Furthermore, due to the power lines characteristics, the proposed input power structure can act as AC to DC or as DC to DC converter providing a proper DC output voltage range required to the DC bus. When operation is AC to DC, the converter is capable to provide high power factor with reduced harmonic distortion for the input current, complying with the restrictions imposed by IEC 61000-3-4 standard. Finally, the main experimental results are presented in order to verify the feasibility of the proposed converter, demonstrating the benefits and the possibility for AC feeding system for trolleybus type vehicle. © 2010 IEEE.

A social network approach to trust management in VANETs

In the past few years, vehicular ad hoc networks(VANETs) was studied extensively by researchers. VANETs is a type of P2P network, though it has some distinct characters (fast moving, short lived connection etc.). In this paper, we present several limitations of current trust management schemes in VANETs and propose ways to counter them. We first review several trust management techniques in VANETs and argue that the ephemeral nature of VANETs render them useless in practical situations. We identify that the problem of information cascading and oversampling, which commonly arise in social networks, also adversely affects trust management schemes in VANETs. To the best of our knowledge, we are the first to introduce information cascading and oversampling to VANETs. We show that simple voting for decision making leads to oversampling and gives incorrect results in VANETs. To overcome this problem, we propose a novel voting scheme. In our scheme, each vehicle has different voting weight according to its distance from the event. The vehicle which is more closer to the event possesses higher weight. Simulations show that our proposed algorithm performs better than simple voting, increasing the correctness of voting. © 2012 Springer Science + Business Media, LLC.

Boosting optimum-path forest clustering through harmony Search and its applications for intrusion detection in computer networks

In this paper we propose a nature-inspired approach that can boost the Optimum-Path Forest (OPF) clustering algorithm by optimizing its parameters in a discrete lattice. The experiments in two public datasets have shown that the proposed algorithm can achieve similar parameters' values compared to the exhaustive search. Although, the proposed technique is faster than the traditional one, being interesting for intrusion detection in large scale traffic networks. © 2012 IEEE.

Planejamento e prototipagem de uma rede social de gastronomia convergente com programas de TV e mídias sociais

Pós-graduação em Televisão Digital: Informação e Conhecimento - FAAC

Explorando potencialidades para a criação de rede de apoio social a mulheres lusófonas que vivem com câncer de mama em Toronto, Canadá

Introduction: Health indicators tend to be altered due to the participation of people in social networks. Objective: To find out ideas of individuals belonging to Portuguese speaking communities in Toronto, Canada, about the possibility of creating a social support network for women experiencing breast cancer. Method: Nineteen participants of the present ethnographic and critical study answered to questions, providing their opinions regarding to the social support network and its positive and negative aspects. Also, the participants suggested other possible individuals who could participate and help in the creation of such network. Discussions were transcribed, analysed and coded using qualitative software called Atlas ti 6.0. Results: The main components for the creation of the social support network were: the demystification of breast cancer and its prevention, emphasis in health education, dissemination of the need of volunteers and a direct social support to those women. The positive aspects were the participation of oldest women as social leaders and the utilization of schools and religious institutions for publicity. Negative aspects that were perceived as barriers are: the belief that breast cancer is a disease lived by women, the lack of knowledge about its cure and rehabilitation, as well as a collective sensitiveness to it. Also, about the participation of community leaders, the suggestions were: diplomats, priests and pastors, schools directors and communication entrepreneurs. Conclusion: The creation of the social support network should consider the cultural sensitiveness and the inner diversity of the consulted Portuguese speaking communities. Due to the insufficient number of Angolan participants to sustain a major analysis, a special recommendation was that Angolan social leaders and professionals should be invited to design the structure of such network according to their specific cultural traits.

Social TV Unesp: proposta de aplicativo em segunda tela com ênfase em modelo de negócios para TV Universitária UNESP

The audiovisual market carefully observes a tendency in television consumption habit: viewers are increasingly watching television content while surfing the internet through mobile devices like tablets, smartphones and laptops. Known as second screen, viewers interact simultaneously across these devices, sharing information about the programming on social networks, seeking additional information about the contents well aired, in addition to being likely to purchase products and services on platforms of mobile-commerce persuaded by the scheduling of programming through commercials. Given this, the aim of this article is to propose and prototyping an application visually in second screen with emphasis on business model with possible application on TV Unesp, where the viewer to interact with the programming through the application is exposed to previously scheduled ads, links to mobile-commerce and posts indicating purchase suggestions.

The transformation between exploration and exploitation applied to inventors of packaging innovations

While the inventor is often the driver of an invention in the early stages, he/she needs to move between different social networks for knowledge in order to create and capture value. The main objective of this research is to propose a literature-based framework based on innovation network theory and complemented with C-K theory, in order to analyze the invention/innovation process of inventors and the product concepts in a packaging industry context. Empirical input from three case studies of packaging inventions and their inventors is used to elaborate the suggested framework.The article identifies important gaps in the literature of innovation networks. This is addressed through a theoretical framework based on network theories, complemented with C-K theory for the product design level. The strength-of-ties dimension of the theoretical framework suggests, in agreement with the mainstream literature and the cases presented, that weak ties are required to access the knowledge related to exploration networks and strong ties are required to utilize the knowledge in the exploitation network. The transformation network is an intermediate step acting as a bridge where entrepreneurs can find required knowledge. The transformation network is also an intermediate step where entrepreneurs find financing and companies interested in commercializing inventions. (C) 2010 Elsevier Ltd. All rights reserved.

Redes sociais e comunidades virtuais para a preservação e transmissão das tradições gaúchas na Internet

Considerando a potencialidade apresentada pelas tecnologias de informação e comunicação na atualidade este estudo aponta as formas pelas quais grupos sociais mobilizados em torno de uma vinculação étnica podem se servir do aparato da Internet, em especial do World Wide Web, para divulgar aspectos de sua cultura e modo de vida. Trata-se de grupos dedicados ao ensino, transmissão, preservação e disseminação da tradição gaúcha vinculados aos Centros de Tradições Gaúchas (CTG). Especificamente, este artigo apresenta como os tradicionalistas gaúchos estabelecem suas redes sociais na Internet, constituindo comunidades virtuais em torno do tema cultura e tradição gaúcha, fazendo uso dos serviços da Web 2.0. Abordam-se neste estudo experiências que indicam que o terreno virtual é fértil e possível de transformar e revolucionar o campo das tradições, sua preservação, disseminação e (re)invenção. No contexto de modernidade tardia esse recurso não pode ser descartado. Independente da análise se situar no campo econômico, político ou cultural, entre tantos outros, o fato é que a Internet se constitui num meio eficaz e abrangente de transmitir, ensinar e preservar conteúdos de todos os tipos.