RCAAP Repository

In this paper we are studying cryptography’s evolution throughout history; analyzing the difference between symmetric and asymmetric cryptographies; enunciating definitions and theorems about binary relations, group theories, primitive roots and discrete logarithms; understanding the procedure of Diffie-Hellman’s key change protocol. In the last part in this work, we are proposing three activities to be applied in classroom.

This paper is a survey on representation of integers as sums of squares for the cases where we have the sum of two, three and four squares. The idea is to study conditions so that we can ensure the representation of numbers that are written as the sum of two and four square. The central focus is the statement of the theorem of Lagrange four squares, although we have gone a little further studying Fermat' s technique of in nite descense and the case n = 3 of Fermat's last theorem. Finally, we work with the development of a didactic sequence that can be used in the nal grades of elementary school and middle school, addressing Chapter 2 of this dissertation.

In this work we study the main topics about Mathematical Finance, seeking for immediate connection with our reality. We study some subjects discussed in High School in order to provide basic tools for decision making in our daily lives. We also studied an electronic tool that helps us to solve several problems that have extensive calculations.

We present the concepts of Di erential and Integral Calculus needed to mathematically model some physics concepts geared to the movement. We also present physical situations that are possible to model the mathematical tools of high school, as well as suggestions for ideas mathematical content of higher education that could be posed to high school students enriching media to discuss these problems more complex physics movement.

This paper presents an introductory study of graph theory, considering its relevance to the teaching of mathematics. Initially presents a brief history on Graph Theory. Then the rst chapter consists of some de nitions on graphs and examples, the second chapter deals with the paths, walks and cycles in a graph, highlighting the Eulerian tours and Hamiltonian cycles, also boarded a special type of graphs, trees . In Chapter 3 we address the planarity in graphs, thus presenting Euler's Formula. Finally in Chapter 4 we present some problems involving graphs.

This work starts with the presentation of the concept of at gures closed polygonal area. Respecting the historical aspect, we display the method of exhaustion, proposed by Archimedes, with concentration in the areas of circular regions bounded by parabolic curves. Arriving near the modernity we introduced the concepts of limit, continuity, derivative and integrals converging on the so-called Fundamental Theorem of calculus and its application in the calculation of areas in a more friendly than the method of Archimedes.

Cerebrovascular Accident (CVA) is a disease characterized by an interruption of blood flow to the encephalon, which represents the leading cause of long-term disability and functional impairment in adult population. Therefore, the individual who had suffered CVA needs to access health services that offer rehabilitation assistance as they promote a better physical, functional, and mental capacity, helping the reinsertion and reintegration of this individual into society. Thus, this study aims to develop a decision-making model to determine the access to physiotherapy services for rehabilitation of patients who had suffered acute CVA in the cities of João Pessoa and Cabedelo. This is an observational-longitudinal study among man and women who were admitted at a public hospital in João Pessoa and live in its metro area, who had presented CVA as primary cause of hospitalization. A questionnaire was used containing items related to socioeconomic, demographic, and clinical data from this person, such as general health conditions, risk factors, functionality evaluation, and access to physiotherapy services. Interviews were conducted between 15 and 21 days after hospital discharge (T0) and between 90 and 105 days after the first interview (T1). There was a homogeneous distribution of sexes, group age over 60 years (mean age= 61.6 years; standard deviation= 15.7 years). Most of the subjects (69.2%) have had a ischemic CVA, which the right side was more affected (46.2%) and 89.7% have had up to two CVA episodes. From interviewed patients, 69.2% have not had access to physiotherapy services after three months from the first interview. For utilization of decision model, 16 variables were selected helped by WEKA software, generating a feedfoward Artificial Neural Network model composed by 16 neurons in the input layer, followed by two hidden layers with two hidden neurons in each layer and an output layer with 2 neurons with backpropagation learning. This decision model allowed classifying correctly almost all subjects that accessed or not the physiotherapy services, achieving 97.4% of successes, representing a greater reliability. Therefore, this model is constituted as an important tool in the visibility of the problem, helping in the decision-making process, planning, and reorganization of public health system and its several attention levels.

This work presents an active power filter for three-phase three-wire systems without an inductor when compared to the usual structure of a shunt active power filter. For the determination and control of the references it was used the Park’s transformation, it means that all control was done in synchronous axes. The active filter of this work is in parallel configuration acting therefore as a current source and should correct the power factor and current harmonics selectively of the power grid. Simulation results were presented validating the control strategy.

This work deals with the evaluation of the communication system by radio frequency using the NRF-24L01+® transceiver to be used in monitoring of electrical systems on the concept of smart grid. The complete system consists of one or more Units Remote Data Acquisition - URDAs; multiple Smart Sensing Units - SSUs; and Supervisory Control Subsystem - SCS. The connection between URAD and SSUs may occur via wired connection (Ethernet, RS232, USB, CAN or PLC) and wireless (RF). URADs fit to the acquisition, processing and communication of variables with low time constant while the USIs are primarily responsible for the acquisition of magnitudes with larger time constants (temperature, pressure, humidity, etc.). In this work, we focus on development and communication of SSUs. For these tests the units are of two types: a master unit, responsible for requesting data (wireless) and sending the SCS (Communication RS232, USB, CAN or RF); and a slave unit, which may account for the measured variables of interest to send to the master unit when requested. For wireless communication (RF), the transceiver nRF - 24L01+® from NORDICTM was used, because its processing characteristics and communication satisfactorily meet the needs and requirements of the project, which will be addressed in the course of this work.

This work to characterize a thermoelectric device as a electrical power generator. For this propose, a thermoelectric cell was submit to different temperature profiles on his faces. The application of heat on the device was made through a feeded back controled structure with cascade Peltier cells, temperature sensors and current circuit drivers. The execution and the monitoring of this was made by an interface of acquisition and data control connected to the computer and managed by a software dedicated to this application. With this experiments was observed the electrical voltage response from the thermoelectric device in relation to temperatures applied to his faces. Also was inserted a resistive charge for behavior analysis of the electrical power provided by the device. Among the obtained results, stand out the variation of the Seebeck coefficient when the average of work’s temperature changes. The power provided by the thermoelectric device setted as generator comes to 95 mW when submitted to a temperature difference ((ΔT) in 40 ºC. The power and current curves are showed in relation to the voltage generated by the device.

The present work aims to simulate the effects of connecting photovoltaic power plants in the active energy losses of the distribution system at the west of the state of Paraíba. Initially was done the modeling of the distribution system, which has one supply point, 20 substations 69/13.8 kV and 25 distribution lines 69 kV. For network analysis was used the Newton-Raphson method for solution of power flow after and before the insertion of photovoltaic plants and finally an optimized allocation of solar photovoltaic plants has been proposed with the aim of minimizing losses of active power using genetic algorithms.

In this work a characterization of harmonic content in residential electrical systems through a set of measurements over various periods of time is performed. For each reported case it was a statement of charges that make up the installation and an individual analysis of each of them as a way to assess their influence on the harmonic behavior of the installation as a whole.

Nowadays, electricity assumes an essential role in the sustainability of modern society. The requirement and consumer demand for power quality are growing along with the advancement of technology and the increasing use of non-linear loads. This paper presents an application of artificial immune systems, focusing on the clonal selection algorithm, for power quality disturbances classification. The algorithm uses an initial population of antibodies to generate high affinity memory cells capable of recognizing antigenic electrical disturbances during each half cycle of the fundamental frequency voltage signal. The results demonstrate the algorithm's ability to classify disturbances such as sag, swell, outage and harmonics, with 100% efficiency rating. Another important feature of this approach is that it can be embedded, since the online stage classification has a low computational complexity with processing time around 103 μs. Based on comparative study with other studies, the results showed up best.

The interest for the study of multiphase (more than three phases) machines and variable speed drives has substantially increased in the last two decades. The advantages presented by the multiphase systems compared to their three-phase counterparts have being the the main effort to increase researches all over the world. Reduction in torque oscillation, lower current ratings, high drive reliability, better fault tolerance and harmonic content reduction in the DC bus are some of these advantages. The additional degrees of freedom due to extra phases make multiphase systems very flexible when it comes to control systems and modulation strategies. Although three-phase systems are predominant in industrial applications, the use of multiphase machines and drives has increased in very specific areas such as locomotive traction, electric ship propulsion, aerospace industry (more electric aircraft), electric and hybrid vehicles and industrial high power systems. Due to high coupling degree between electric variables in multiphase systems, modeling of multiphase machines has been and still is a challenge task in research centers. In this present work, analitic modeling of symmetric and asymmetric nine-phase machines using natural variables and space vector decomposition are presented. The principles used in the study are the same used for three-phase systems. However, multiphase systems are analised in multiple d-q planes. PWM modulation strategies based on space vectors theory (SVPWM) for a voltage source inverter (VSI) are presented. The multiphase drive system presented works in the linear operation region with sinusoidal voltage generation. Results for both machines and drive modeled are verified by simulation programs developed in C programming language an Matlab.

Thinking of a society where part of the population is destined to live their affectivity in secret is to think like these people "admit to himself" a sexuality intended to marginalization and how to face, from the identification of desire itself to the practice of desire. Several studies have shown that even with the existence of social norms that shy away prejudice, discrimination is still active, although it is assuming forms of expression that do not come into direct confrontation with the term of the current standards of tolerance. These discriminatory attitudes and situations of exclusion have created feelings of inadequacy in homoerotic subjects, which is reflected directly on your self-esteem and in carrying out its duties as individuals belonging to the society. Consequently, the homoerotic subjects are seeking emotional support from each other, allowing them to soften the refusal of the harmonic coexistence with the rest of society. So the aim of this study is to investigate the construction of the social experience of the group of women who experience the practice of homoerotic desire as active minorities in a social dynamic characterized by disparaging representations to groups of sexual minorities. Describing how in this universe have developed and expressed the strategies of this experience. In this regard, research is based on five aspects: perception about the causes of homosexuality; Emotional and social factors involved the discovery of homoerotic desire; Perception about the discrimination experienced; Perception about the movements and sexual minorities contributed in the struggle for sexual diversity; and Perception about which are the flags of fights must be prioritized by the movement of sexual minorities. Two studies were carried out for this purpose, the first with sample composed of 81 women who practice the homoeroticism, contacted through networks of contacts; the second study included a sample of 176 women students of humanities courses that had already begun their sexual practice. Analyzing the data obtained in two studies, we can say that if homoerotic women have a vivid perception of the discrimination and prejudice from your homoerotic practices, consequences to which they are subject in society, on the other hand the experience of sexuality is full by feelings of social repression for straight women. Thus, discrimination is felt by this woman, and even more intensely lived by women homoerotic practice, which makes the practice of sexuality lived through the filter normative created and maintained socially.

The autism spectrum involves deviations in development since the early years of life in areas of social interaction, communication and imagination. Numerous researches are performed and many aspects remain inconclusive, especially regarding to the etiology, treatment possibilities and integration in regular schools. Considering the importance of social interaction in children's development and the influence of parent´s and professionals concepts about inclusive practices, the present study aims to analyze the social interactions between children with autism and other children in the context of regular schools in João Pessoa, Brazil, considering the mediation of teachers, parents and their conceptions about the child and school inclusion. A group of 42 children and four teachers from two regular private schools, as well as four children diagnosed with autism spectrum between 3 and 5 years of age and their parents. To collect the data, semi-structured interviews recorded, through a mini tape recorder, were used. Also, two videotapes of 20 minutes were made at each of the situations of courtyard and classrooms, of which 10 minutes were transcribed and analyzed. With the objective to characterize the children in this study we used the CARS rating scale. Regarding data analysis, interviews were transcribed and analyzed using the technique of content analysis. The recordings were transcribed and analyzed using behavioral categories of teachers and children with autism described in qualitative terms, from case studies, and quantitative, from the frequencies. The results show that parents are satisfied with the educational inclusion held with their children. These parents point positive characteristics of their children, while identifying the difficulties inherent in autism. As for the teachers observed those are reformulating their conceptions of the possibilities of these children and understand inclusion as a practice that goes beyond the inclusion in school. In relation to the behaviors in both the classroom and in the courtyard there was a higher frequency in the use of directives and physical support. With regard to the autistic child there was a greater frequency of behaviors to look at people, led initiative to action, appropriate response and smile revealing the participation of autistic children in interactional terms. Considering that the behaviors of these children can be influenced by the interactive contexts, the mediation of adult and, especially, the particularities of each child this study aims to support guidelines for parents and professionals mainly regarding the inclusion of autistic children in regular schools.

The main objective of this thesis was to investigate the role of the contact maintained via internet with Blacks and Northeasterners in the relationship between prejudice and discrimination against these groups. To achieve the proposed objective, five studies were carried out. In the first three, the instruments that would later be used were developed, and the similarities and differences between regional and racial bias were established. In the last two studies, the aim was to investigate the role of types of contact (maintained on the Internet, in-person, and extended) in the perception of bias against groups of Blacks and Northeasterners, as well as their roles in mediating the relationship between prejudice and discrimination. To carry out study 1, a list of adjectives was used where participants chose the most representative features of the groups of Blacks and Northeasterners. The results of study 1 indicated a strong similarity in assigning adjectives to the group of Northeasterners and Blacks. This process of stereotyping was similar to that found in surveys conducted ten years earlier with groups of Blacks, which demonstrates a constancy of the content of these stereotypes. Study 2 contained the list of adjectives used in Study 1, as well as measures of prejudice and identification with the group of Blacks and Northeasterners. The main result was the evidence of the existence of a process of essentialization in the categorization of Northeasterners, similar to what happens with the group of Blacks. In this sense, the Northeasterners were not evaluated in terms of the characteristics of their region, but by stereotypes referencing natural and biological characteristics, thus approaching the existing explanations for racial prejudice. To conduct study 3, a scenario was developed where an alleged unfair selection occurred during the hiring process for a position as salesman in a store. The context of injustice varied over two conditions. In the first, a black person competing with a white person for the position, the latter was hired, even though both had the same qualifications. In the second condition, the story was the same, with a northeasterner competing with a southern candidate for the position as salesman, and the latter was hired. It was up to the participants to judge the selection as fair or unfair, and then explain their answers. The results showed a similarity in the discursive repertoires for both conditions: the Black individual and the Northeasterner, which corroborates the results of studies 1 and 2. To carry out studies 4 and 5, measures of contact were used, which were categorized in three ways: contact maintained via Internet (number of friends that participants had exclusively in the virtual environment); personal contact (number of friends that participants had in their everyday relationships); and extended contact (number of friends and relatives that respondents possessed and which were related to the group of Blacks and Northeasterners). The results of study 4 presented contact maintained on the internet with Blacks and Northeasterners as a better predictor of perceived discrimination committed against these groups. The result of study 5 indicated that the internet contact maintained with Blacks and Northeasterners mediated the relationship between prejudice and discrimination, such that the more contact maintained with Blacks and Northeasterners on the internet, the lower were the rates of discrimination against these groups. Taken together, the results indicate that contact via internet with Blacks and Northeasterners may have a positive effect in building a more positive image of these groups.

The study of vulnerability to sexually transmitted diseases seeks at understanding the different risks that any individual has of getting contaminated, due to individual and social characteristics that can be relevant to a greater exposure to the human immunodeficiency virus (HIV). Based on this premise, grounded on the Theory of Planned Behavior, the Theory of Control Locus, and the Vulnerability Model, two studies were conducted. Study 1 aimed at carrying out a survey about women’s beliefs about masculine preservative use by the partner. Study 2 aimed at investigating the behavior intention of women toward preservative use. Results from Study 1, based on a convenience sample of 35 women from low socioeconomic status in the city of João Pessoa, demonstrated behavioral beliefs regarding the advantages of using preservative, highlighting the knowledge of its contraceptive role and its function for preventing sexually transmitted diseases. Nevertheless, disadvantages were also mentioned, such as being uncomfortable and reducing pleasure when the partner uses preservative. As positive model references for preservative use, they mentioned family and doctors, and as negatives, friends and partner. Based on the results of the first study, an instrument was developed and answered by 244 women, comprising Study 2, which had as independent variables Indirect Attitudes, Direct Attitudes, Subjective Norm and Perceived Control, and as dependent variable, the Intention of using preservative. It was observed that the variable Perceived Control (β= .43) was the main responsible for the explained variance of the intention of preservative use, followed by the dimension Subjective Norm (β = .30). Direct Attitude (β= .15) had a good significance level, but small explanatory power. Moreover, it was verified that most women who declared using contraceptive pills declared safe sex is practiced “sometimes”. On the other hand, most of the women who do not make use of contraceptive pills declared that they “always” use preservative. Significant correlations between the four dimensions of locus of control and behavior intentions were not found. These results can be considered a reference for studies and interventions about the importance of preservative use in sexual relations.

The use of drugs constitutes in the last years one of the most serious and hard to solve social phenomena nowadays. The crack has stood out in the Brazilian scenery regarding to other drugs gaining high social visibility. At the moment, it is understood that the consumption of drugs happens in all social groups; however the abusive use of crack by female users has been reported as a growing phenomenon in our society. It was aimed, based on a psychosocial comprehension of the phenomenon, to know and analyze the social representations about the crack, elaborated by female chemical dependents in treatment, using the theoretical contribution of the Social Representations Theory. It is a qualitative research, with descriptive and field character and, performed in Therapeutic Communities and Rehabilitation female Clinics, located in the estates of PB and PE. It was composed of a non-probabilistic sample and by convenience with a total of 45 users. The instruments used were: social demographic questionnaire, analyzed through the calculation of simple frequencies and percentages; the Free Association of Words, with the stimuli: crack and woman user, which was analyzed through the Analysis of Content; and, semi structured interview, that was analyzed with the software ALCESTE. The application of instruments happened in an individual status and in the institutions with help of a recorder; all the ethic procedure that involve the research with human beings were respected. The results indicated that the crack is represented as devastating and disruptive element, as it generates situations of disorder in the family environment, and is responsible for causing abandon or removal of the feminine functions. It was verified that the figure of woman user is seen as a moral order problem, causing a present depressing representation in the society; the dissonance between “being a drug user” and “being a mother/housewife” have influence in these speeches. It was also observed, that the strategies to combat this issue are loaded with of repression and endorsed by speeches that rule the prism of the morality, expressing the inequality of gender that still persists in the relation of the feminine with the masculine. These constructions, at the same time are individual and social; exert influence on how the society faces the chemical dependent woman, reinforcing social barriers that make difficult looking for a treatment and recovery of the users. Therefore, we conclude that it is necessary a look ahead of the stigmatization of the woman, that must be seen, before the role of wife or mother, as a woman that suffers and so needs care. This study provided an opportunity for the debate about this issue, having as objective strategies of combat and contemplation of these problems by public policies that help in the treatment of the chemical dependent woman.

This dissertation aimed at determining the extent to which personality traits, mediated by human values, predict psychopaths phenotypes. In this sense, three empirical studies were carried out. Study 1 aimed to adapt to the Brazilian context the Triarchic Psychopathy Measure (TriPM). Participants were 498 undergraduate students of public and private universities from João Pessoa (Brazil), with a mean age of 22 years (SD = 7.79), they responded to TriPM and demographic questions. Initially, we verified the discriminative power of items, item 35 was eliminated for not differentiate participants with close scores. Subsequently, a Principal Component Analysis was performed by fixing varimax rotation and extraction of three factors, it was possible to identify a solution with acceptable reliability indicators and each dimension being formed by nine items: Disinhibition (α = .73), Boldness (α = .73) and Meanness (α = .81), together explaining 25.6% of the total variance. Study 2 aimed to test the adapted version. Participants were 230 people from the general population, with mean age 26.9 years (SD = 8.87), who responded the TriPM version with 27 items and demographic questions. Alternative models were tested, but the three factors was more acceptable (e.g., GFI = .81; RMSEA = .05). With preliminary evidences attesting to the adequacy of TriPM proceeded to the Study 3, aiming to verify the mediating role of human values in the relationship between personality traits and psychopathy. Participants were 228 undergraduate students of public and private universities from João Pessoa (Brazil), with a mean age of 25.1 years (SD = 7.51) who answered TriPM, Big Five Inventory, the Basic Values Questionnaire and demographic questions. The results indicated that personality traits and values were good predictors of psychopathic phenotypes, moreover, confirmed the mediating role of values in the relationship between personality and psychopathy. It is estimated that the objectives were achieved, with the adaptation of a self-report measure for the estimation of psychopathic traits in general population, with preliminary evidence for its factorial validity and internal consistency, and increasing the understanding that has been around psychopathy from the relationships it establishes with other constructs.