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Social media makes it possible for anyone to share and transmit their opinions and sentiments to the rest of the world via the Internet. Recently, sentiment analysis is being used to investigate the opinions posted on Online Social Networks(OSN) based on multiple inputs, such as user profile characteristics, slang, emoticons, among others. However, the current sentiment analysis tools do not consider the influence of tagging people on OSN. In this context, this paper analyzes the impact of the tagging parameter on the global sentiment score of a text. The experimental results of subjective tests show that a correction factor must be considered in case of tagging people. Experimental results demonstrate that the tagging parameter affects the sentiment intensity value, in different ways, depending on the gender of the person who wrote the text and the sentiment polarity of the text. The new sentiment intensity metric considering the tagging people parameter reaches a Pearson Correlation Coefficient of 0.93 and a maximum error of 0.07, for texts of negative polarity written by women, at a 5-point scale. Furthermore, a mobile application with the new sentiment metric, which considers the tagging parameter, is built.

Telecommunication operators need tools to evaluate and improve the quality of the their services offered. In the case of telephony services, the speech quality perceived by the users is relevant. There are different speech quality assessment methods, one of them is the parametric method that is generally used in network planning. The ITU-T Rec. G107, and its recent updates, is the most representative parametric method. However, it does not consider the impairments occurred in a wireless channel. In this context, we propose the inclusion of parameters, such as fading channel model, signal-to-noise ratio (SNR), and maximum Doppler shift using different modulation schemes. Several wireless communication scenarios were simulated using actual speech samples as input. Then, the impairment speech samples were evaluated by an intrusive signal-based method described in ITU-T Rec. P.862.2, which results are used as ground-truth. Experimental results demonstrated that there is a high correlation between wireless channel parameters and mean opinion score (MOS) index. Thus, an impairment wireless function, namedI w is proposed and added to the E-model wide-band algorithm. Performance validation test results demonstrated thatI w represents a reliable wireless degradation model, reaching a Pearson correlation coefficient (PCC) and a normalized RMSE (NRMSE) of 0.973 and 0.085, respectively.

Currently, Voice over IP (VoIP) communication service is widely used mainly because its lower cost. However, the quality of a VoIP communication is lower than a fixed-line communication due to network degradations. In this context, the objective of this work is to evaluate the quality of voice communications that undergo degradations in the wireless interface, and how MIMO technology helps to improve the voice signal quality. For this, a simulator named WVoIPSim is built, in which different modulation schemes, an error correction coding and different noise levels in wireless channel are implemented. The resulting speech signal, at the receiver, is analyzed by the ITU-T Recommendations P.862 and P.563, in which P.862 is used as reference. Experimental results show that there is a high correlation between MIMO system configurations and speech quality scores. Based on these results, different MIMO configurations for different network conditions is proposed in order to guarantee a MOS score higher than 4.0.

IP networks have provided many services, such as telephone communications. However, the Packet Loss Rate (PLR) can occur on IP networks and it can affect the users Quality of Experience (QoE). In this case, it is important to perform the assessment of the speech quality and to implement a methodology to predict speech quality. Thus, this paper presents a nonintrusive speech quality model based on Hybrid Discriminative Restricted Boltzmann Machines (HDRBM), in order to identify speech quality classes. A speech database with different PLRs was built and a quality index was found for each file. The experimental results of the performance assessment showed that the proposed model based on HDRBM overcame the ITU-T recommendation P.563. Subjective tests presented 97.11% of precision using the proposed Speech Quality Classifier performed by the HDRBM approach.

Currently, social networks has been used for its users, and exploited by mechanisms of quality measurement systems and recommendation of products and services. The Recommendation Systems (SR) have used the data of the social networks and in parallel they have applied the sentiment and affective analysis in such data. However, there is still a concern in increasing the accuracy of the sentiment and affective analysis. This article introduces an SR, which extracts the texts of the users of the social networks and suggests musical styles based on the sentiment analysis by lexical approach and based on the affective analysis through the machine learning. The Convolutional Neural Network algorithm used for the emotion classification of hapiness, sadness, anger, fear, disgust and surprise presented a precision higher than the found in related works. Classification results of the F-Measure were of 0.98 e 0.96 for the emotion of sadness and anger, respectively. In addition, SR was assessed by means of subjective tests and the experimental results show that 97% of users approved the SR proposal.

Os serviços telefonicos baseados em redes IP são muito utilizados ao redor do mundo. No entanto, uma taxa de perda de pacotes (PLR) pode ocorrer em redes IP, afetando a qualidade de experiência (QoE) dos usuários, sendo necessário avaliar a qualidade da voz. A determinação de uma metodologia para prever uma qualidade da voz é relevante e necessária. Consequentemente, este artigo apresenta um modelo não intrusivo de classificação de qualidade de voz, baseado em aprendizagem profunda utilizando cinco classes. Foi construída uma base de dados, na qual diferentes PLRs são aplicadas e o índice de qualidade de cada arquivo foi calculado. Os resultados experimentais mostram que o desempenho do modelo proposto supera a Recomendação ITU-T P.563.

In recent years, the shared mobility service has increased in many countries across the world because its low cost and several shared-use mobility applications on mobile devices. Commonly, if a ride is shared between people with similar preferences, users likely feel both more comfortable and safer. In this context, the main goal of this article is to classify users with similar preferences, in automatic manner, to improve user’s quality of experience in ridesharing service. To obtain initial data, subjective tests are carried out using questionnaires and their results are used to determine ridesharing profiles. Then, some basic user profile information is extracted from Online Social Networks (OSN) to determine an user profile based on preferences in ridesharing service. The user profile classification is performed through different machine learning algorithms, which use as input the data extracted from OSN. Two case studies of shared-mobility are treated, (i) sharing a ride with a passenger with a similar hobby [2], and (ii) sharing a ride with people that support an opposite football teams. In this work, a novel contribution is the use of Hybrid Discriminative Restricted Boltzmann Machines (HDRBM) technique for classification, which results overcomes other algorithms, such as Random Forest, SVM and DRBM. The experimental results presented a correctly classified instance of 96:9% and 97:3% for the cases of sharing a ride with people with similar hobby and support different football team, respectively. Finally, a Recommendation System (RS) is proposed, which efficiency is compared with a basic RS, obtaining a Pearson correlation coefficient of 0:97 and 0:79, respectively.

In general, blogs have simple texts, which are of easy assimilation; however, due to the large number of blogs in recent years, it is often difficult to choose one. This research studies the use of the sentiment and affective analysis in a recommendation system (RS) of blogs through texts extracted from a social network. Some blogs of different themes are selected and previously classified according to the polarity of their texts. A recommendation of blogs is carried out, according to the relationship between the sentiment and affective analysis of both, the blog content and the texts posted by users. Results show that the use of sentiment and affective analysis improved the RS performance reaching 89% of users' acceptance, against to 55% when sentiment and affective analysis is not considered. Also, the system interface implemented in a mobile device is evaluated considering an ergonomic criteria set.

This work describes an information system regarding to the telecommunication service with the goal to inform to the telephony service users about the operators signal quality and the users’ opinion about the telecommunication operators. The system contains information of cellular base station locations and the results are crossed with sentiment analyses of sentences extracted from a social network, which are related to the telecommunication services. The study aims to detect complaints and dissatisfaction of users about a determined service, helping to make a relation between the users’ complains extracted from social network with the number of base stations in the same geographic area of the user's social network. Therefore, the proposed information system can be used by the National Telecommunications Agency of each country for monitoring the quality-of-service of cellular network operators.

Este artigo descreve um sistema de segurança para ser utilizado em sistemas de informação baseado na biometria da íris. O processo de autenticação de usuários em um sistema de informação é de suma importância e pode ser realizado usando diversos métodos como: senhas alfanuméricas, certificação digital, dispositivos eletrônicos gerador de senhas ou sistemas que reconhecem características humanas, como é o caso da íris. Um sistema biométrico de íris consta das seguintes etapas: aquisição, segmentação, normalização, extração de padrões e finalmente a etapa de reconhecimento, que consiste na verificação ou validação do usuário no sistema. Cada uma dessas etapas possui relação com o desempenho do sistema biométrico. Nesse contexto, o objetivo principal deste trabalho é estudar o impacto da qualidade da imagem da íris, na etapa de aquisição e o seu desempenho global do sistema biométrico implementado, estabelecendo limiares mínimos de qualidade para garantir uma adequada autenticação do usuário no sistema. Os resultados experimentais demonstraram que os parâmetros de falsa aceitação e rejeição diminuem se um limiar de qualidade é estabelecido.

In video streaming service, the user's Quality of Experience (QoE) is not only related to video signal quality received at consumer's devices, the users’ subjectivity must also be considered. In this context, a video quality assessment method that takes into account the user's preference for video content is proposed in this research. In order to perform this task, the users' profiles that include their preferences were stored in a video server. Then, subjective tests of video quality assessment were conducted, in which evaluators had different video content preferences. Results show that the evaluators' QoE is highly correlated with the user's preference for video content type. Based on these experimental results, a function named Preference Factor (PF) is defined and used to adjust the quality index values obtained by an objective video quality metric running in the end user's device. The PF function also depends on video content type and quality index score. Using the PF function, the enhanced Video streaming Quality Metric (e-VsQM) is proposed and the results of its performance evaluation demonstrate that PF improves an objective video quality metric. Furthermore, e-VsQM has low complexity and can be utilized in different video services. Thus, an application scenario is presented, in which the proposed video quality metric is implemented.

Nowadays, there are several multimedia services, which are carried via IP networks. From these services, the traffic regarding video applications had the greatest growth in the last years. In this context, the study of methods for assessing video quality plays a very important role. In general, video quality objective metrics are defined from mathematical models, which use as inputs, different network or application layer parameters, and the video quality assessment results from subjective tests. This paper aims to demonstrate that the video quality metric performance can be improved by adding a parameter regarding the video content type. In order to perform video quality assessment tests in a short time period, the so-called crowdsourcing methodology is used. In this methodology remote users assess the video quality. The experimental results show that the Video streaming Quality Metric (VsQM) performance is improved when the video content type is considered (eVsQM). Indeed, the Pearson correlation factors between eVsQM and crowdsourcing results reach 0.94 - 0.98, depending on the video degradation scenario. TRAFEGO projetado para video em Internet, excluindo compartilhamento de arquivos e jogos, alcancara em 2016, 55 % do trafego total da Internet (1). Este incremento de trafego se deve a existencia de diferentes servicos de aplicacoes de video sobre uma rede IP, sendo que um dos servicos que mais sofreu evolucao nos ultimos anos foi o de streaming de audio e video armazenados. Exemplos do sucesso deste tipo de servico considerando a popularidade que alcancaram sao: Youtube, Dailymotion, Vimeo, Microsoft Video, entre outros. Por outro lado, os servicos em tempo real, como a videoconferencia (exemplo, NetMeeting e video Skype) ou streaming de audio e video ao vivo que sao mais conhecidas como radio da Internet e IPTV, tambem experimentaram um incremento consideravel no numero de usuarios (2). Com este incremento de trafego de video, os fornecedores de servicos de video devem preparar-se para atender este alto volume de informacao (3). Tambem, neste contexto, cabe salientar que o estudo de metodos e metricas de avaliacao de qualidade do sinal do video e de suma importância. Existem protocolos que nao sao orientados a conexao e conseguintemente, nao garantem a entrega de informacao no destino; estes protocolos sao geralmente utilizados em

The study of quality reception of audio signals in auditoriums is relevant because this fact determines the user's Quality of Experience (QoE). This paper presents experimental results regarding to the impact of the linear phase variations on the voice quality index. Speech files are played using different phases, and each audio transmitted is individually saved. Later, the original and the transmitted speech files are compared using a voice quality assessment metric. Experimental results demonstrate that the phase-angle is highly correlated with the voice quality index; therefore, a relation function between the angle and the quality index is proposed.

Viewing quality assessment is important in every phase of coder development and deployment, and also in the design and operation of video streaming services. In the development and design phases an objective metric is more cost-effective and less time-consuming than a subjective assessment. The behavior of the impairment caused by packet-delay-variation (PDV) over quality inspires the conception of the viewing-quality-objective metric (VQOM), which is proposed here. A single spline function is used as a prototype whose parameters are trained by a deterministically constrained mean square error statistical method. Test results are presented for a sizable database of Absolute Category Rating (ACR) subjective scores corroborating the assumptions in the definition of VQOM.

This paper presents a mechanism to provide a real-time assessment of voice quality on mobile handled devices. This solution considers the voice degradations caused by the radio frequency channel and packet losses on the IP network. Furthermore, the network architecture of the proposed solution is introduced and the application is implemented on the user mobile device.

Wireless Ad-Hoc Networks (WANETs) need algorithms and protocols that may provide higher packet delivery throughput for non-structured networks with a high degree of mobility. Moreover, the possibility of reducing the broadcasting packages that will heavily consume power resources on nodes is extremely important. This paper studies the implementation of a modification in the epidemic algorithm, a direction-biased Gossip associated with a Quorum system applied into LAR routing protocol in a fault scenario of an ad-hoc network. The simulation results show that the new association decreases the number of energy consumption without degrading the message delivery ratio.

This paper presents a recommendation system based on sentiment analysis of sentences extracted from Social Networks considering an algorithm which depends on the adverb found in the sentence. Furthermore, the recommendation system has a low complexity, therefore the perceived impacts on the analysis of energy consumption on electronic devices is almost negligible.

There is a wide range of video services over complex transmission networks, and in some cases end users fail to receive an acceptable quality level. In this paper, the different factors that degrade users' quality of experience (QoE) in video streaming service that use TCP as transmission protocol are studied. In this specific service, impairment factors are: number of pauses, their duration and temporal location. In order to measure the effect that each temporal segment has in the overall video quality, subjective tests. Because current subjective test methodologies are not adequate to assess video streaming over TCP, some recommendations are provided here. At the application layer, a customized player is used to evaluate the behavior of player buffer, and consequently, the end user QoE. Video subjective test results demonstrate that there is a close correlation between application parameters and subjective scores. Based on this fact, a new metrics named VsQM is defined, which considers the importance of temporal location of pauses to assess the user QoE of video streaming service. A useful application scenario is also presented, in which the metrics proposed herein is used to improve video services.

There is a wide range of telecommunications services that transmit voice, video and data through complex transmission networks and in some cases, the service has not an acceptable quality level for the end user. In this sense the study of methods for assessing video quality and voice have a very important role. This paper presents a classification scheme, based on different criteria, of the methods and metrics that are being studied in recent years. This paper presents how the video quality is affected by degradation in the transmission channel in two kinds of services: Digital TV (ISDB-TB) due the fading in the air interface and video streaming service on an IP network due packet loss. For Digital TV tests was set up a scenario where the digital TV transmitter is connected to an RF channel emulator, where are inserted different fading models and at the end, the videos are saved in a mobile device. The tests of streaming video were performed in an isolated scenario of IP network, which are scheduled several network conditions, resulting in different qualities of video reception. The video quality assessment is performed using objective assessment methods: PSNR, SSIM and VQM. The results show how the losses in the transmission channel affects the quality of end-user experience on both services studied.

The outstanding features of a vehicle do not include great modifications for nearly 100 years, as the same to the major car manufacturers' business models (BM). Recent service's platforms related to urban mobility use, mostly, the sharing economy, resulting in disruptive innovations. This offer to the users new experiences in services (e.g., Uber) which provides the vehicle's use without the onus of ownership. From this perspective, this paper qualitatively evaluates the modifications in the automakers BM's standards based on strategies and innovations of the new businesses of the main groups of automotive manufacturers. As a result, we observed that traditional products-based automakers are already moving towards to fit in the new BM, which are impacted by the sharing economy. Finally, we proposed a framework based on an unbundled model operating synergistically in three types (customer relationship management, product/service innovation and infrastructure management).

This paper presents a mechanism to provide a real-time evaluation of speech quality. This solution consists of a voice-quality-server (VQS) based on the ITU-T P.563 algorithm with modifications to treat natural silences of human speech and packet losses on the network. Furthermore, an application is implemented on the user device.

This paper presents a monitoring solution for users with potential psychological disturbs, specifically stress. The phrases extracted from Social Networks are filtered by mood and scored using a sentiment-analysis-metric that considers personal characteristics, such as gender and age. The solution informs, to authorized persons, the emotional changes of the users.

This work proposes a no-reference video quality metric that considers two parameters, pauses and changes in video resolution. Results indicate that users' Quality-of-Experience (QoE) is highly correlated with these parameters. The proposed metric has low complexity because it is based on application-level parameters; it can, therefore, be easily implemented in consumer electronic devices.

Dynamic adaptive streaming over HTTP (DASH) has become a promising solution for video delivery services over the Internet in the last few years. Currently, several video content providers use the DASH solution to improve the users’ quality of experience (QoE) by automatically switching video quality levels (VQLs) according to the network status. However, the frequency of switching events between different VQLs during a video streaming session may disturb the user’s visual attention and therefore affect the user’s QoE. As one of the first attempts to characterize the impact of VQL switching on the user’s QoE, we carried out a series of subjective tests, which show that there is a correlation between the user QoE and the frequency, type, and temporal location of the switching events. We propose a novel parameter named switching degradation factor (SDF) to capture such correlation. A DASH algorithm with SDF parameter is compared with the same algorithm without SDF. The results demonstrate that the SDF parameter significantly improves the user’s QoE, especially when network conditions vary frequently.

Atualmente existem inúmeros serviços multimídia que são transportados através da rede IP, dos quais, o tráfego dos serviços de vídeo experimentou um maior crescimento nos últimos anos. O sucesso de aplicações de streaming de vídeo é um dos fatores pelo qual, este tráfego se incrementou. Alguns recentes estudos projetam que este tipo de serviços no ano 2016, alcançará aproximadamente o 55% do tráfego total da Internet. Considerando a importância que os serviços de vídeo alcançarão nos próximos anos, este trabalho foca-se na avaliação da qualidade de experiência (QoE) dos usuários ao utilizar estes serviços. Assim, nesta tese é proposta uma métrica de avaliação de vídeo denominada eVsQM, do inglês enhanced Video streaming Quality Metric, a qual é baseada principalmente no número, duração e localização temporal dos congelamentos de imagens (pausas) durante uma transmissão de vídeo, considerando também o tipo de conteúdo do vídeo transmitido. Esta métrica foi determinada a partir de um modelo matemático que utilizou os resultados de testes subjetivos de avaliação de vídeo, pois, este tipo de testes são os que melhor se aproximam da QoE real do usuário. Cabe destacar, que na realização dos testes subjetivos foi utilizada uma metodologia concordante com o tipo de degradação que o vídeo possui, ou seja, a pausa. No streaming de vídeo novas soluções são criadas com a finalidade de melhorar a QoE do usuário. O DASH, do inglês Dynamic Adaptive Streaming over HTTP, muda a resolução do vídeo transmitido de acordo com as características da rede. Porém, se a rede é muito flutuante existirão muitas variações de resolução e a QoE do usuário será degradada. Neste trabalho é proposto um parâmetro a ser utilizado no algoritmo DASH que funciona como um limiar para controlar a frequência destas comutações de resolução. Este parâmetro é denominado como SDF (do inglês Switching Degradation Factor) e permite que a QoE mantida em níveis aceitáveis, inclusive em situações onde a rede é muito flutuante. Adicionalmente, neste trabalho é proposto um novo modelo de faturamento nos serviços de telecomunicações, que inclua no processo de tarifação um parâmetro relacionado com a QoE, visando ter uma tarifação de serviços de comunicações mais justa do ponto de vista dos usuários. Desta forma, usuários que recebem uma menor qualidade no serviço devem pagar menos em relação aos usuários que recebem uma melhor qualidade do mesmo serviço. Nowadays, there are several multimedia services, which are carried via IP networks. From these all services; the traffic regarding video applications had the greatest growth in the last years. The success of video streaming applications is one of the major contributors to video traffic growth. Some recent studies project that video services, will reach approximately 55% of the total Internet traffic in 2016. Considering the relevance that video services will achieve in the coming years, this work focuses on the users Quality of Experience (QoE) when using these services. Thus, this thesis proposes an evaluation metric named enhanced Video streaming Quality Metric (eVsQM), which is based primarily on the number, duration and temporal location of the image freezes (pauses) during a video transmission. Also, this metric considers the video content type and was determined from a mathematical model that used as inputs, the video quality assessment results from subjective tests due, these types of test are the most correlated with real users QoE. It is worth noting that to perform these subjective tests was used a methodology consistent with the kind of video degradation (pause). For another hand, new video streaming solutions are created for the purpose of improving the users QoE of the user. Dynamic Adaptive Streaming over HTTP (DASH) changes the video resolution according to the network characteristics. However, if the network is very fluctuant, many video resolution switching events will be performed and users QoE will be degraded. This thesis proposes a parameter to be used in DASH algorithms that works as a threshold to control the resolution switching frequency. This parameter is named Switching Degradation Factor (SDF) and is responsible to maintain the QoE in acceptable levels, inclusive in scenarios in which the network capacity is very fluctuating.

The main goal of this paper is to evaluate the performance of the proposed new video coding standard, the High Efficiency Video Coding (HEVC), also known as H.265. This evaluation considers mainly a comparison with the baseline profile of H.264/AVC encoder in terms of: compression efficiency, the video quality achieved by decoding the video signal at the receiver, and the computational complexity of encoding and decoding algorithms. As material test are used different spatial resolutions of video and also videos with different temporal and spatial information parameters. For video quality assessment are used two objective metrics, PSNR and SSIM. Furthermore, a transcoding H.264/HEVC scenario is evaluated considering the cascade method, which is very important for the first service applications that will use HEVC. The results indicate that compressed video file sizes using HEVC is 40-52% in relation with H.264 depending of the video content type without any significant video quality degradation at the receiver.

Cluster computing is widely used for image and video processing in entertainment applications. The video complexity can be experimentally determined according to the time spent to render it in a cluster. This paper analyzes the time spent for rendering 3D videos with different characteristics by a process of ray tracing on a cluster computing with Povray software. For another hand, the video complexity is determined by a novel metric named Video Complexity Index (VCI) that considers both, the spatial and temporal video characteristics. Experimental results demonstrate that VCI metric successfully classifies the videos regarding their complexity, considering the processing time consumed for a cluster. As a consequence, VCI metric can be useful to choose the right number of cluster nodes in accordance to the 3D video complexity.

This article analyzes Brazilian Consumers' Sentiments in a specific domain using a system, SentiMeter-Br. A Portuguese dictionary focused in a specific field of study was built, in which tenses and negative words are treated in a different way of other dictionaries, with a different metric. For the Portuguese dictionary performance validation, the results are compared with the SentiStrength algorithm and are evaluated by three Specialists in the field of study; each one analyzed 2000 texts captured from Twitter. Comparing the efficiency of the SentiMeter-Br and the SentiStrength against the Specialists' opinion, a Pearson correlation factor of 0.89 and 0.75 was reached, respectively. The polarity of the short texts were also tested through machine learning, with correctly classified instances of 71.79% by Sequential Minimal Optimization algorithm and F-Measure of 0.87 for positive and 0.91 for negative phrases.

This work proposes a novel billing system model for voice call services on cellular networks, which includes the voice quality index estimated on the end user device as an additional parameter in the charging process. The solution proposed is focused on cellular networks, and the main goal is to improve the user's quality of experience (QoE) using the voice call service, because users pay according to their satisfaction level. Voice quality assessment tests were conducted, in which users evaluate different voice call qualities and fill a survey regarding the service costs. Results show how the service costs are correlated with the user' QoE. Furthermore, the solution network architecture is presented, which uses the mechanisms introduced in a 3GPP project named Minimization Drive Test. Also, the technical feasibility of the solution implementation in a commercial cellular network is demonstrated.

There are several subjective test methodologies for assessing video quality, being that each of these methods was developed by considering specific degradation factors in video quality. Therefore, for video streaming services that use TCP as transport protocol different evaluation criteria should be considered as compared to current methods, because the impairment are only pauses. In this paper, the concepts of the mechanisms that integrate perceptual and cognitive processes are studied, relating them to a test environment for subjective evaluation of video, which is limited to streaming video service transmitted via HTTP / TCP. For this reason, some recommendations to perform subjective assessment of streaming video service are proposed, taking into account perceptual and cognitive criteria. In this work, subjective tests are conducted, evaluators with different content preferences assess 3 different video content. Results show that the assessors' QoE depends strongly on video content preferences. Thus, assessors who are interested in the video content are more drastic in the ratings. In the case of sport videos, the Mean Opinion Score (MOS) value of assesors with explicit preference in sports reachs only 54% of the MOS obtained by assessors without interest in sports. Furthermore, the roll of the instructor during the test is also evaluated.

This paper introduces new network architecture capable of providing a flexible and configurable Recommendation System in which network operator, subscribers and content providers could interact to each other by message exchanging. This solution considers multiple inputs provided by the user and context-based information of IP Multimedia Subsystem (IMS) network. It creates a specific subscriber profile based on information from cellular and fixed networks, digital TV and, internet services as social networks or e-mail accounts. Also, for collecting information is used a Cell Broadcast platform which can send messages to a specific geographic location achieving users with high probability of similar preferences. User feedback is collected to evaluate the utility of recommendation messages. As additional features, the Recommendation System uses presence and location information as a decision factor to send or not the recommendation messages.

In this contribution we present the controlled synchronization of complex networks of dynamical systems using geometrical control issues. The controlled synchronization consists into induce a prescribed behavior onto the whole elements of the complex network. To this end, we propose a controller obtained from the geometrical control theory for nonlinear systems. The control action is applied only to a one or a small number of systems in the network but not to all. Thus, via the controlled systems the desired behavior is induced to the whole network. Simulation results are provided to corroborate the proposal.

The increasing use of mobile devices in wireless environments led to many studies about power-aware algorithms and protocols to improve the lifetime of device’s battery. This paper studies the implementation and testing of a new power-aware algorithm, PSWA, associated with a Cache System, and tested with the WRP routing protocol, in a Mobile Ad hoc Network scenario. A scheme that does not use the sleep schedule for the nodes it was used, nodes automatically fall asleep if they do not deal with data and routes. In the simulation scenario the WRP was chosen because it has a better performance in real-time traffic, and this type of traffic is commonly used today. The simulation results show an important decrease in energy consumption close to 10% with the association of the new power-aware algorithm.

The cluster computing is widely used for image processing in entertainment applications. Measuring the required number of nodes to be used in a cluster computing helps saving nodes processing time, even if this occurs on a fault tolerant scenario. The paper analyzes the images rendering process by ray tracing on the cluster computing using the freeware software fault tolerant message-passing interface with Povray software in a Linux-based operating system. This paper uses a simple method of image complexity measure, it is shown that depending on the images complexity level, a minimum number of cluster nodes is chose to render the image instead of using all the cluster nodes. It is useful to save machine processing time and meanwhile another image can be rendered in a parallel process with a previous one and where the solution is applied in a Fault Tolerant scenario, so independent of the network fault, the cluster continues working.

Resumo - Perda de pacotes e atrasos influenciam na qualidade de uma conversa interativa em uma rede IP. Este artigo mostra uma metodologia para predizer o comportamento de diferentes codificadores, utilizando modelo s objetivos como o PESQ e a Recomendacao E-Model do ITU-T. A metodologia apresentada e util para medir a performance de novos codificadores, ou de codificadores que ainda nao possuam parâmetros definidos em diferentes cenarios de perda de pacotes e atrasos, em uma comunicacao bidirecional utilizando uma rede emulada com open source software, sendo o cenario facilmente reproduzido.