A contribuition to the study of channel coding in wireless communication systems

Pós-graduação em Engenharia Elétrica - FEIS

Analysis of the influence of baffles and shields on the cooling of a digital transmission equipment

In this work design criteria for cooling of electronic systems used in a digital transmission equipment are considered. An experimental study using a simulated electronic equipment in which vertically oriented circuit boards are aligned to form vertical channels is carried out. Resistors are used to simulate actual components. The temperature of several components in the printed circuit boards are measured and the influence of the baffles and shields on the cooling effect are discussed. It was observed that the use of the baffles reduce the temperature levels and, the use of shields, although protecting the components from magnetic effects, cause an increase in the temperature levels.

Efficacy of several digital radiographic imaging systems for laboratory determination of endodontic file length

P>AimTo compare the efficacy of different digital radiographic imaging systems for determining the length of endodontic files.MethodologyK-type endodontic files were introduced into the canals of 40 extracted human permanent single-rooted teeth and fixed in place at random lengths. The teeth were radiographed using Digora Optime (R), CygnusRay MPS (R) and CDR Wireless (R) digital imaging systems. Six observers measured every file length in all the images and repeated this procedure in 50% of the image samples, and assigned a score to the level of difficulty found. Analysis of variance for differences between digital systems and Tukey's test were performed. The level of intraobserver agreement was measured by intraclass correlation. The assigned scores were evaluated by Kruskal-Wallis and Dunn's tests.ResultsThe CDR Wireless values did not differ significantly from the actual lengths and the CygnusRay MPS values. The Digora Optime system was significantly different from the others and overestimated the values (P < 0.05). The Digora Optime was significantly easier to use for taking measurements and the CygnusRay MPS the most difficult (P < 0.05). All digital radiographic imaging systems showed excellent agreement with the Intraclass Correlation Coefficient > 0.95.ConclusionsThe three digital radiographic imaging systems were precise. The CDR Wireless system was significantly more accurate in determining endodontic file lengths, and similarly to Digora Optime, was considered the least difficult to use when assessing endodontic file lengths.

New approach of induction machine drive using an adaptive digital PID controller with gain planning based on artificial neural networks

The present work introduces a new strategy of induction machines speed adjustment using an adaptive PID (Proportional Integral Derivative) digital controller with gain planning based on the artificial neural networks. This digital controller uses an auxiliary variable to determine the ideal induction machine operating conditions and to establish the closed loop gain of the system. The auxiliary variable value can be estimated from the information stored in a general-purpose artificial neural network based on CMAC (Cerebellar Model Articulation Controller).

Digital radiographic evaluation of optical density of porcelains used for fabrication of inlay/onlay prosthesis

The purpose of this article was to compare the mean value of optical density of four porcelains commonly used for fabrication of inlay/ onlay prostheses using direct digital radiograph. The sample consisted of 20 2-mm thick porcelain specimens (measured by digital pachymeter): Empress (Ivoclair), Simbios (Degussa), Vita Omega 900 and Vitadur Alpha (Vita Zahnfabrik). The values of optical density of the specimens were expressed in millimeters aluminum equivalent (mm eq Al). The samples were X-rayed using two charge coupled devices (CCD) - RVG (Trophy) - Visualix (Gendex) and a phosphor plate system - Digora (Soredex). The optical density reading was performed with Image Tool 1.28 in a total of 110 measurements. Statistical analysis showed that there were statistically significant differences in all materials studied (p < 0.05) regardless of the radiographic system used. The highest optical density value was found for Omega 900 (1.8988 mmeqAl - Visualix - Gendex) and the lowest for Vitadur Alpha (0.8647 - Visualix - Gendex). Thus, the material presenting the highest degree of optical density was Omega 900, Empress and Simbios presented intermediate optical density values, Vitadur Alpha presented the lowest value, and the optical density of porcelains was not influenced by the digital radiography systems.

Pricing of reactive power support provided by distributed generators in transmission systems

Distributed Generation, microgrid technologies, two-way communication systems, and demand response programs are issues that are being studied in recent years within the concept of smart grids. At some level of enough penetration, the Distributed Generators (DGs) can provide benefits for sub-transmission and transmission systems through the so-called ancillary services. This work is focused on the ancillary service of reactive power support provided by DGs, specifically Wind Turbine Generators (WTGs), with high level of impact on transmission systems. The main objective of this work is to propose an optimization methodology to price this service by determining the costs in which a DG incurs when it loses sales opportunity of active power, i.e, by determining the Loss of Opportunity Costs (LOC). LOC occur when more reactive power is required than available, and the active power generation has to be reduced in order to increase the reactive power capacity. In the optimization process, three objectives are considered: active power generation costs of DGs, voltage stability margin of the system, and losses in the lines of the network. Uncertainties of WTGs are reduced solving multi-objective optimal power flows in multiple probabilistic scenarios constructed by Monte Carlo simulations, and modeling the time series associated with the active power generation of each WTG via Fuzzy Logic and Markov Chains. The proposed methodology was tested using the IEEE 14 bus test system with two WTGs installed. © 2011 IEEE.

H ∞ state feedback control of discrete-time Markov jump linear systems through linear matrix inequalities

This paper addresses the H ∞ state-feedback control design problem of discretetime Markov jump linear systems. First, under the assumption that the Markov parameter is measured, the main contribution is on the LMI characterization of all linear feedback controllers such that the closed loop output remains bounded by a given norm level. This results allows the robust controller design to deal with convex bounded parameter uncertainty, probability uncertainty and cluster availability of the Markov mode. For partly unknown transition probabilities, the proposed design problem is proved to be less conservative than one available in the current literature. An example is solved for illustration and comparisons. © 2011 IFAC.

As multiplicidades espaciais na comunicação midiática digital

Pós-graduação em Comunicação - FAAC

Os processos de comunicação interna das organizações no contexto das tecnologias da comunicação digital: reflexões a partir das práticas de interatividade da geração y

Pós-graduação em Comunicação - FAAC

Serviço de referência e informação para smartphones: análise de acesso e uso

Pós-graduação em Ciência da Informação - FFC

Diretrizes de usabilidade para programas interativos de entretenimento para público idoso em TV Digital

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

Comunicação digital, relações públicas e gestão de marcas: Interatividade e relacionamento como ferramentas de branding

This paper aims to present the contribution of Public Relations in the process of branding, using digital communication as a tool for interaction with the public, and through strategic management, building and maintaining strong and lasting relationships with consumers, resulting in building bonds of sympathy, identification, and networks engaged and loyal consumers to brands. Therefore, were performed bibliographical research covering topics such as information society, network society, the dynamics of social networks, digital media, brands, branding, marketing 3.0, Public Relations and Public Relations 2.0. Were also undertaken observations on communication actions that used digital social media, focusing on interactivity, collaboration and relationship, to better understand how organizations are realizing the importance of interaction and relationship management with the public and how they are performing this communication. At the end, some of these actions are presented as examples of the theories studied, and as a demonstration of the benefits brought to these organizations and their brands

Televisão e mídias digitais na América Latina: um cenário em construção

The text is the initial result of a project called Global iTV, Interactive and systems Hybrid TV: a new advanced scheme for future services and applications in a global environment, contemplated by Call MCTI / CNPq 13/2012 – EUBrazil Cooperation Program in the field of Information and Communication Technologies (ICT) which has as its central theme the development of a standard that enables interoperability between the various digital TV systems operating jointly, exchanging and using information. Thus, using bibliographical and documentary research, the article goes on to demonstrate how this perspective panorama is drawing from the advent of digital television and the use of technology in Latin America, seeking to identify similarities, differences, problems and solutions arising from the use and consumption of digitizing television signal in the region. The results demonstrate the importance of media convergence, but point out that there are still large sections of the population on the margin of the Digital Society and the benefits provided by digital networks and that poverty and poor education are important contributions to this scenario.

Implementação e avaliação do protocolo μTESLA: proposta de uso nas redes veiculares

Pós-graduação em Ciência da Computação - IBILCE

A segunda tela na tv digital brasileira: um estudo dos processos midiáticos interativos

Pós-graduação em Comunicação - FAAC