6 resultados para Equações de segundo grau. Soluções. Mudança de variáveis

em Universidade Federal de Uberlândia


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This study has as object eight state vocational schools located in Araguari, Araxá, Frutal, Ituiutaba, Monte Carmelo, Patos de Minas, Uberaba and Uberlândia, in Minas Gerais. The period analyzed comprises the years from 1965 to 1976, from the signature of the Agreement 512-11-610-042 beteween the Ministry of Education and Culture (MEC) and the American Agency for International Development (USAID), which started a series of other agreements, and actions ending up with the creation of the Expansion and Improvement of High Schools Program (Programa de Expansão e Melhoria do Ensino Médio - PREMEM) and, from this, the Vocational Schools. The upper limit of the study, 1976, was the year when these agreements, known as MEC/USAID agreements ceased. The Vocational Schools were characterized as vocation probing schools, directing the professional formation of the population in general, which would happen a posteriori, turning it shorter and more effective, since the labor market would demand, urgently, capable professionals for an expanding economy. The project of Vocational Schools had a national scope, and foresaw, for its unfolding, the complete substitution of State Schools for the new model, called “multi-curricula”. The theme Vocational schools was the object of my Master’s degree study, when I focused the State School Guiomar de Freitas Costa, in Uberlândia. That study raised questionings and concerns that resulted in the central problem of the thesis presented here: understanding the measure in which such schools integrated the country’s development project – mostly in the first half of the military rule – and to understand its structure, functionality and efficacyThe development of the study presented here, demanded the use of several sources: 1) specialized literature about the topics presented, i.e., the situation of national education in a temporal analysis, the political, economical and social context, research methodologies, the theory of human capital, vocational teaching, pedagogical trends and practices, agreements MEC-USAID and PREMEM; 2) national, state and county laws related to the discussion: laws of national education directives and basis, decrees and reports stating about the program of technical cooperation between Brazil and the United States of America, the Program of Expansion and Improvement of Teaching (PREMEM), formation of professors, establishment of Vocational Schools and educational planning; 3) documentation of school archives: books of minutes of Collegiate and of faculty and staff, registrar books with final scores, enrolment, visits of inspector, accounting books, punch clock records, student, professor and staff occurrences, inventory, class schedules, school year calendar, school rules, class reports, payment rolls, bills of sales, exchanged mail, personal documentation of professional personnel, documents of land acquisition, blueprints, manuals of PREMEM, didactic materials/resources used in classes, books available in the school library, structured evaluations for follow-up of school processes, pictures of events, texts prepared for special dates, and news from the official newspaper and, finally, 4) national and local press reports, especially from Folha de São Paulo, Correio de Araxá, Correio de Uberlândia and Lavoura e Comércio (Uberaba). The proposition of Vocational schools was conciliate theoretical and practical formation through an active education permeated by technological resources. The contact with knowledge and several practical activities under professional supervision, the student would identify the knowledge area that would interest him the most and his aptitude. This formation in primary school would make way for the vocation studies in high school, which became mandatory by the law 5.692/71, that reformed school education from the previous levels of elementary, middle high and high school. However, the multi-curricula proposal that would be spread to the other public schools in the country ended up succumbing to the model already established. From its ephemeral existence, maybe the Vocational Schools have not reached the more general goals in political, economic and social aspects; however, this study demonstrated that, for the people that, directly or indirectly, had contact with such schools, a legacy of vocational and quality teaching was made, so much so, that forty years after the end of that proposal, they are still remembered.

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This work contributes to the finance literature proposing to analyze the relationship between the degree of internationalization of Brazilian companies and the likelihood of delisting. Therefore, even though the internationalization as a differential, in the formulation of hypotheses and analysis of the relationship between the variables dealt with concepts and theories within the Corporate Governance, which is already established in theory when it comes to delisting. First, with a view to the theory of internalization, which gives competitive advantages to the company due the adoption internationalization strategy and in parallel to the positive effects that this strategy generates on firms performance, it was formulated an hypothesis that the degree of internationalization would be adversely related to the probability of delisting, mainly due to such benefits generated to the organization. In turn, as an alternative hypothesis of the research, it proposed a positive relationship between these variables, based on agency theory, according to which internationalization would contribute to delisting by increasing geographical separation between shareholders and managers and, consequently, agency conflicts and the difficulty of monitoring. For the achievement of objectives, as well as being included economic and financial variables and GC, it was proposed the analysis of periods of crisis, as the events of recent past of the Brazilian economy. Starting from a base model initially developed by Pour and Lasfer (2013), which later, the proxies of internationalization and crisis have been added also contemplating adjustments to the Brazilian context. The data collected include the period from 2006 to 2014 and information on active and inactive companies at Bovespa. As results, it was found negative significance between the degree of internationalization and the delisting decision, confirming the first hypothesis of the research and stating that the benefits generated by internationalization in the company generate it spreads and results that reduce the probability of delisting. By analyzing the results of control variables was still possible to observe that, even internationalization reducing the likelihood of delisting, by particular aspects of corporate governance in Brazil, such as the high ownership concentration, the benefits it generates contribute to delisting. Regarding the analysis in crisis, the consequences of the crisis of the US subprime in general market were more relevant that the occurrence of itself, unlike the Brazilian internal crisis of 2014, which was statistically significant for the analyzed event. For future researches it is suggested the expansion of database and individual treatment of the reasons adopted by a company when delisting decision.

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The intervention research proposed was based on the Cultural-Historical Theory based on the laws and logic of materialism historical-dialectical. Therefore, we tried to design a research process that involved all as responsible for the process. In the field of continuous teacher's training usually has been found dualistic relationship / paradoxical processes as a result of the adopted training models which are characterized by individualist human processes. The teacher training work sought to overcome this dualism, to promote the unveiling of the contradictions with regard to teaching models. As a hypothesis, we imagined that immersed in this process, teachers recognize such contradictions, and this recognition would make the contradictions become the driving force of change in teaching practice, realizing the teaching-learning-development triad as the basis of praxis. Aiming to develop a process of continuing education to bring results to the professional teachers development looking for answer the following research question: How and what the changes of teachers who participated in the Didactic-Formative Intervention process raised the quality of their teaching practices? In this context, the objective of the research was to develop a process of Didactic-Formative Intervention from the perspective of Cultural-Historical Theory with high school teachers in order to theorize about the changes in pedagogical practices of teachers and learn aspects that transform the essence teaching practice. The research involved two high school teachers of a public school in Uberlândia-MG. The training meetings took place at the school through a collective study group between the years 2013 and 2015. As procedures were used two interconnected aspects: classes observations, and a theoretical and methodological training, both for diagnosis and for the process evaluation, the second aspect has a formative dimension, and a didactic dimension (double meaning) to form didactically the teacher and to elaborate didactic procedures. The collected data were analyzed by observing the assumptions of the method, analysis by units and the processuality. As results teachers showed changes in their teaching practices regarding the organization of the pedagogical work and also centered their design educational actions based on learning and development of the students. The presence of continuous diagnosis during the classes, work with a systems of concepts and their conceptual links, problematization as a teaching method can be pointed as meaningful changes in their praxis. Regarding the training activities that emerged from the analysis of the compiled materials and analyzed throughout the process can be emphasized: forming a collective group of school teachers continuous training, diagnostics, development of practical activities, increase relationships among participants, the choice of scientific material used should have direct relation to the needs of the participants, promoting conditions that enable the emergence of contradictions between the pedagogical practice of teachers and teaching based on the perspective of the Cultural-Historical Theory. This research craved to develop and design a teachers' training processes that increase the quality of teachers life and ways of teaching in the Brazilian public school.

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Faced with an agribusiness expansion scenario and the increase in fertilizer consumption due to the exponential growth of the population, it is necessary to make better use of existing reserves, by obtaining products of better quality and in adequate quantities to meet demand national. In Tapira Mining Complex, Vale Fertilizantes, the phosphate concentrate is produced with content of 35.0% P2O5 from ore with content of about 8.0% P2O5, which are intended to supply Complex Industrial Uberaba and Araxá Minero Chemical Complex for the production of fertilizers. The industrial flotation step responsible for the recovery of P2O5 and hence the viability of the business is divided into the crumbly, grainy and ultrathin circuits, and, friable and granular concentrate comprise the conventional concentrated. Today only 14.7% of the mass which feeds the mill product becomes, the remainder being considered losses in the process, and the larger mass losses are located in the waste of flotation, representing 42.3%. From 2012 to 2014, the daily global mass recovery processing plants varied from 12.4 to 15.9% while the daily metallurgical recovery of P2O5 from 48.7 to 82.4%. By the degree of variability, it appears that the plant operated under different conditions. Seen this, this study aimed to analyze the influence of operational and process variables in P2O5 mass and metallurgical recoveries of industrial flotation circuits of grainy, crumbly and ultrathin. And besides was made an analysis of the effect of ore variables, as degrees, hardnesse and the ore front 02 percentage, in global recoveries of processing plant and the effect of dosages of reagents in the recoveries obtained from the bench flotation using the experimental design methodology. All work was performed using the historical database of Vale Fertilizantes of Tapira-MG, where all independent variables were dimensionless as the experimental range used. To make the statistical analysis it used the response surface technique and the values of the independent variables that maximize recoveries were found by canonical analysis. In the study of industrial flotation circuit crispy were obtained from 41.3% mass recovery and 91.3% metallurgical recovery P2O5, good values for the circuit, and the highest recoveries occur for solids concentration of the new flotation power between 45 and 50%, which values are assigned to the residence time of the pulp in cells and industrial flotation columns. The greater the number of ore heaps resumed on the higher the mass recovery, but in this scenario flotation becomes unstable because there is enormous weight variation in the feed. Higher recoveries are obtained for mass depressant dosage exceeding 120 g / t for synthetic collector dosage of 11.6%. In the study of industrial flotation circuit of the granulate were obtained 28.3% to 79.4% mass recovery and metallurgical recovery of P2O5 being considered good values for the circuit. Higher recoveries are obtained when the front ore 02 percentage is above 90%, because the ore of this front have more clear apatite. Likewise recoveries increase when the level of pulp rougher step is highest due to the high mass of circulating step receives loads. In the analysis of industrial flotation circuit of the ultrafine were obtained 23.95% of mass recovery, and the same is maximized to depressant dosage and the top collector 420 and 300 g / t, respectively. The analysis of the influence of variables ore, it was observed that higher recoveries are obtained for ores with P2O5 content above 8.0%, Fe2O3 content in the order of 28% forward and 02 of ore percentage of 83%. Hard ore percentage has strong influence on recoveries due to mass division in the circuit that is linked to this variable. However, the hard ore percentage that maximizes recoveries was very close to the design capacity of the processing plant, which is 20%. Finally, the study of the bench flotation, has noted that in friable and granular circuits the highest recoveries are achieved for a collector dosage exceeding 250 g / t and the simultaneous increase of collector dosage and synthetic collector percentage contributes to the increase recovery in the flotation, but this scenario is suitable to produce a concentrate poorer in terms of P2O5 content, showing that higher recovery is not always the ideal scenario. Thus, the results show the values of variables that provide higher recoveries in the flotation and hence lower losses in the waste.

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In this work it was developed mathematical resolutions taking as parameter maximum intensity values for the interference analysis of electric and magnetic fields and was given two virtual computer system that supports families of CDMA and WCDMA technologies. The first family were developed computational resources to solve electric and magnetic field calculations and power densities in Radio Base stations , with the use of CDMA technology in the 800 MHz band , taking into account the permissible values referenced by the Commission International Protection on non-Ionizing Radiation . The first family is divided into two segments of calculation carried out in virtual operation. In the first segment to compute the interference field radiated by the base station with input information such as radio channel power; Gain antenna; Radio channel number; Operating frequency; Losses in the cable; Attenuation of direction; Minimum Distance; Reflections. Said computing system allows to quickly and without the need of implementing instruments for measurements, meet the following calculated values: Effective Radiated Power; Sector Power Density; Electric field in the sector; Magnetic field in the sector; Magnetic flux density; point of maximum permissible exposure of electric field and power density. The results are shown in charts for clarity of view of power density in the industry, as well as the coverage area definition. The computer module also includes folders specifications antennas, cables and towers used in cellular telephony, the following manufacturers: RFS World, Andrew, Karthein and BRASILSAT. Many are presented "links" network access "Internet" to supplement the cable specifications, antennas, etc. . In the second segment of the first family work with more variables , seeking to perform calculations quickly and safely assisting in obtaining results of radio signal loss produced by ERB . This module displays screens representing propagation systems denominated "A" and "B". By propagating "A" are obtained radio signal attenuation calculations in areas of urban models , dense urban , suburban , and rural open . In reflection calculations are present the reflection coefficients , the standing wave ratio , return loss , the reflected power ratio , as well as the loss of the signal by mismatch impedance. With the spread " B" seek radio signal losses in the survey line and not targeted , the effective area , the power density , the received power , the coverage radius , the conversion levels and the gain conversion systems radiant . The second family of virtual computing system consists of 7 modules of which 5 are geared towards the design of WCDMA and 2 technology for calculation of telephone traffic serving CDMA and WCDMA . It includes a portfolio of radiant systems used on the site. In the virtual operation of the module 1 is compute-: distance frequency reuse, channel capacity with noise and without noise, Doppler frequency, modulation rate and channel efficiency; Module 2 includes computes the cell area, thermal noise, noise power (dB), noise figure, signal to noise ratio, bit of power (dBm); with the module 3 reaches the calculation: breakpoint, processing gain (dB) loss in the space of BTS, noise power (w), chip period and frequency reuse factor. Module 4 scales effective radiated power, sectorization gain, voice activity and load effect. The module 5 performs the calculation processing gain (Hz / bps) bit time, bit energy (Ws). Module 6 deals with the telephone traffic and scales 1: traffic volume, occupancy intensity, average time of occupancy, traffic intensity, calls completed, congestion. Module 7 deals with two telephone traffic and allows calculating call completion and not completed in HMM. Tests were performed on the mobile network performance field for the calculation of data relating to: CINP , CPI , RSRP , RSRQ , EARFCN , Drop Call , Block Call , Pilot , Data Bler , RSCP , Short Call, Long Call and Data Call ; ECIO - Short Call and Long Call , Data Call Troughput . As survey were conducted surveys of electric and magnetic field in an ERB , trying to observe the degree of exposure to non-ionizing radiation they are exposed to the general public and occupational element. The results were compared to permissible values for health endorsed by the ICNIRP and the CENELEC .

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The hydrocycloning operation has a goal to separate solid-liquid suspensions and liquid-liquid emulsions through the centrifugal force action. Hydrocyclones are equipment with reduced size and used in both clarification and thickening. This device is used in many areas, like petrochemical and minerals process, and accumulate advantages like versatility and low cost of maintenance. However, the demand to improve the process and to reduce the costs has motivated several studies of equipment optimization. The filtering hydrocyclone is a non-conventional equipment developed at FEQUI/UFU with objective to improve the hydrocycloning separation efficiency. The purpose of this study is to evaluate the operating conditions of feed concentration and underflow diameter on the performance of a filtering geometry optimized to minimization of energy costs. The filtration effect was investigated through the comparison between the performance of the Optimized Filtering Hydrocyclone (HCOF) and the Optimized Concentrator Hydrocyclone (HCO). Because of the resemblance of hydrocyclones performance, the filtration did not represent significant effect on the performance of the HCOF. It was found that in this geometry the decrease of the variable underflow diameter was very favorable to thickening operation. The suspension concentration of quartzite at 1.0% of solids in volume was increased about 42 times when the 3 mm underflow diameter was used. The increase on the feed solid percentage was good for decreasing the energy spent, so that a minimum number of Euler of 730 was achieved at CVA = 10.0%v. However, a greater amount of solids in suspension leads to a lower efficiency of the equipment. Therefore, to minimize the underflow-to-throughput ratio and keep a high efficiency level, it is indicated to work with dilute suspension (CVA = 1.0%) and 3 mm underflow diameter (η = 67%). But if it is necessary to work with high feed concentration, the use of 5 mm underflow diameter provides a rise in the efficiency. The HCO hydrocyclone was compared to the traditional family of hydrocyclones Rietema and presented advantages like higher efficiency (34% higher in average) and lower energy costs (20% lower in average). Finally, the efficiency curves and project equation have been raised for the HCO hydrocyclone each with satisfactory adjust.