Análise da eficácia de um refrigerador doméstico com condensador modificado: revestimento com meio poroso dissipativo

The development of home refrigerators generally are compact and economic reasons for using simplified configuration. The thermodynamic coefficient of performance ( COP ) is limited mainly in the condenser design for reasons of size and arrangement ( layout ) of the project ( design ) and climatic characteristics of the region where it will operate. It is noteworthy that this latter limitation is very significant when it comes to a country of continental size like Brazil with diverse climatic conditions. The COP of the cycle depends crucially on the ability of heat dissipated in the condenser. So in hot climates like the northeast, north, and west-central dispel ability is highly attenuated compared to the south and southeast regions with tropical or subtropical climates when compared with other regions. The dissipation in compact capacitors for applications in domestic refrigeration has been the focus of several studies, that due to its impact on reducing costs and power consumption, and better use of the space occupied by the components of refrigeration systems. This space should be kept to a minimum to allow an increase in the useful storage volume of refrigerator without changing the external dimensions of the product. Due to its low cost manufacturing, wire on tube condensers continue to be the most advantageous option for domestic refrigeration. Traditionally, these heat exchangers are designed to operate under natural convection. Not always, the benefits of greater compactness of capacitors for forced outweigh the burden of pumping air through the external heat exchanger. In this work we propose an improvement in convective condenser changing it to a transfer mechanism combined in series with conductive pipes and wire to a moist convective porous medium and the porous medium to the environment. The porous media used in the coating was composed of a gypsum plaster impregnated fiber about a mesh of natural cellulosic molded tubular wire mesh about the original structure of the condenser , and then dried and calcined to greater adherence and increased porosity. The proposed configuration was installed in domestic refrigeration system ( trough ) and tested under the same conditions of the original configuration . Was also evaluated in the dry condition and humidified drip water under natural and forced with an electro - fan ( fan coil ) convection. Assays were performed for the same 134- refrigerant charge e under the same thermal cooling load. The performance was evaluated in various configurations, showing an improvement of about 72 % compared with the original configuration proposed in humidification and natural convection.

Uso de metamaterial em antenas de microfita com supercondutor

Metamaterials have attracted great attention in recent decades, due to their electromagnetic properties which are not found in nature. Since metamaterials are now synthesized by the insertion of artificially manufactured inclusions in a specified homogeneous medium, it became possible for the researcher to work with a wide collection of independent parameters, for example, the electromagnetic properties of the material. An investigation of the properties of ring resonators was performed as well as those of metamaterials. A study of the major theories that clearly explain superconductivity was presented. The BCS theory, London Equations and the Two-Fluid Model are theories that support the application of superconducting microstrip antennas. Therefore, this thesis presents theoretical, numerical and experimental-computational analysis using full-wave formalism, through the application of the Transverse Transmission Line – LTT method applied in the Fourier Transform Domain (FTD). The LTT is a full wave method, which, as a rule, obtains the electromagnetic fields in terms of the transverse components of the structure. The inclusion of the superconducting patch is performed using the complex resistive boundary condition. Results of resonant frequency as a function of antenna parameters are obtained. To validate the analysis, computer programs were developed using Fortran, simulations were created using the commercial software, with curves being drawn using commercial software and MATLAB, in addition to comparing the conventional patch with the superconductor as well as comparing a metamaterial substrate with a conventional one, joining the substrate with the patch, observing what improves on both cas

Fusões e aquisições no Brasil: análise dos efeitos em mercado de capitais

This study investigated the impact caused by events horizontal mergers and acquisitions (M&As) horizontal, in the stock returns of the participating companies and competitors regarding the creation or destruction of value for those firms in Brazil, from 2001 to 2012. For this, first was used the event study methodology to estimate abnormal returns in stock prices; after was conducted an analysis multiple regression. The results of the event study showed that using sub-periods for the data, before and after the crisis period, the effects were different for the target-before negative, after positive. Regarding the acquirer and competitors, the results were constant. For acquirer firms, the returns were close to zero, while for the competitors were negative. Furthermore, the regression results regarding the bidder showed that firms invested in processes of M&As to obtain a further increase its efficiency. Furthermore, this study indicated that the leverage of the bidder plays is important for creating value in acquisitions, when they has a higher Tobin’s Q. The results of target firms showed that a small firm had a better return than large firm did.

Análise do desempenho de um refrigerador doméstico funcionando com uma válvula de expansão micrométrica

Household refrigerators are equipments that represent a significant portion on the eletricity consumption of Brazilian homes. The use of these devices with low energy efficiency contributes to increase the energy consumption. The energy efficiency of a refrigerator is a function of the interaction between the coolant fluid and the components of the thermodynamic cycle. Changes in load and/or nature of the coolant may modify the condensing and/or evaporation pressures. The volumetric capacity of the compressor, the mass flow of coolant and the compression power are dependent parameters of the condensation and evaporation pressures. Thus, the expansion devices exert an importante role in the balance of these pressures, being fundamental for the better performance of the refrigeration cycle. This experimental research aims to investigate the sensitivity of the performance parameters of a household refrigerator operating with R134a and at different evaporation pressures. Therefore, a small refrigerator was instrumented with temperature, pressure sensors and other variables of interest, installed along the cooling circuit, in order to allow the thermal mapping and the evaluation of the equipment performance parameters. The variation of pressure loss in the coolant fluid resulting from the operation of the expansion valve with micrometric adjustment that modifies the evaporation temperature, influencing significantly the performance parameters of the thermodynamic refrigeration cycle.

Análise de confiabilidade de um moto-ventilador centrífugo: aplicação no sistema de pressurização de subestação industrial para garantia da segurança operacional na indústria petroquímica

The need of the oil industry to ensure the safety of the facilities, employees and the environment, not to mention the search for maximum efficiency of its facilities, makes it seeks to achieve a high level of excellence in all stages of its production processes in order to obtain the required quality of the final product. Know the reliability of equipment and what it stands for a system is of fundamental importance for ensuring the operational safety. The reliability analysis technique has been increasingly applied in the oil industry as fault prediction tool and undesirable events that can affect business continuity. It is an applied scientific methodology that involves knowledge in engineering and statistics to meet and or analyze the performance of components, equipment and systems in order to ensure that they perform their function without fail, for a period of time and under a specific condition. The results of reliability analyzes help in making decisions about the best maintenance strategy of petrochemical plants. Reliability analysis was applied on equipment (bike-centrifugal fan) between the period 2010-2014 at the Polo Petrobras Guamaré Industrial, situated in rural Guamaré municipality in the state of Rio Grande do Norte, where he collected data field, analyzed historical equipment and observing the behavior of faults and their impacts. The data were processed in commercial software reliability ReliaSoft BlockSim 9. The results were compared with a study conducted by the experts in the field in order to get the best maintenance strategy for the studied system. With the results obtained from the reliability analysis tools was possible to determine the availability of the centrifugal motor-fan and what will be its impact on the security of process units if it will fail. A new maintenance strategy was established to improve the reliability, availability, maintainability and decreased likelihood of Moto-Centrifugal Fan failures, it is a series of actions to promote the increased system reliability and consequent increase in cycle life of the asset. Thus, this strategy sets out preventive measures to reduce the probability of failure and mitigating aimed at minimizing the consequences.

Análise de conteúdo e validação clínica do diagnóstico de enfermagem autocontrole ineficaz da saúde

The study aims to analyze the content and measures of accuracy of the nursing diagnosis Ineffective Self Health in patients undergoing hemodialysis. Study of nursing diagnosis validation carried out in two stages, namely: content analysis by judges and accuracy of clinical indicators. In the first stage, 22 judges evaluated the setting and location of the diagnosis, clinical indicators and etiological factors and their conceptual and empirical definitions. We used the binomial test to determine the proportion of the judges of the relevance of the components of the nursing diagnosis. In the second stage, we used the Latent Class Analysis for the diagnostic accuracy by evaluating 200 patients in a hemodialysis clinic in northeastern Brazil. Research approved by the Ethics Committee, under the Opinion No 387 837 and CAAE 18486413.0.0000.5537. The results show that the judges evaluated as pertinent clinical indicators 12 and 22 etiological factors. Proposed amendment of the nomenclature of five indicators and six factors and the implementation of a clinical indicator for etiology and three etiological factors for clinical indicators. In conceptual and empirical definitions, judges judged as not relevant the conceptual and empirical definitions of a clinical indicator, the conceptual definitions of two etiological factors and empirical definitions four etiological factors. Still, changes were suggested in the conceptual and empirical definitions of two clinical indicators, the conceptual definitions of 12 etiological factors and empirical definitions of 11 etiological factors. Clinical indicators analyzed in the first stage were validated clinically in patients undergoing hemodialysis. The most frequent clinical indicators were Changes in laboratory tests (100%) and daily life choices ineffective to achieve health goals (81%); and three etiological factors had a higher frequency, they are: unfavorable demographic factors (94.5%), beliefs (79%) and comorbidities (77.5%). From Latent class analysis, diagnosis prevalence was estimated at 66.28%. Clinical indicators that showed the best sensitivity measures for the nursing diagnosis Ineffective Self Health were: daily life choices ineffective to achieve health goals and Expression of difficulty with prescribed regimens. In turn, the clinical indicators of inappropriate medication use, no expression of desire to control the disease, irregular attendance to the dialysis sessions and infection were more specific as to that diagnosis. Non-adherence to treatment was the only indicator that showed confidence intervals with values for sensitivity and specificity, statistically above 0.5, being the one who has better diagnostic accuracy as the inference of the nursing diagnosis Ineffective Self Health in hemodialysis clientele. Thus, it is believed that the improvement of the components of diagnosis in question will contribute to the development of more reliable nursing interventions to the health status of the individual in hemodialysis, providing a more scientifically qualified care.

Análise de conteúdo e validação clínica do diagnóstico de enfermagem autocontrole ineficaz da saúde

The study aims to analyze the content and measures of accuracy of the nursing diagnosis Ineffective Self Health in patients undergoing hemodialysis. Study of nursing diagnosis validation carried out in two stages, namely: content analysis by judges and accuracy of clinical indicators. In the first stage, 22 judges evaluated the setting and location of the diagnosis, clinical indicators and etiological factors and their conceptual and empirical definitions. We used the binomial test to determine the proportion of the judges of the relevance of the components of the nursing diagnosis. In the second stage, we used the Latent Class Analysis for the diagnostic accuracy by evaluating 200 patients in a hemodialysis clinic in northeastern Brazil. Research approved by the Ethics Committee, under the Opinion No 387 837 and CAAE 18486413.0.0000.5537. The results show that the judges evaluated as pertinent clinical indicators 12 and 22 etiological factors. Proposed amendment of the nomenclature of five indicators and six factors and the implementation of a clinical indicator for etiology and three etiological factors for clinical indicators. In conceptual and empirical definitions, judges judged as not relevant the conceptual and empirical definitions of a clinical indicator, the conceptual definitions of two etiological factors and empirical definitions four etiological factors. Still, changes were suggested in the conceptual and empirical definitions of two clinical indicators, the conceptual definitions of 12 etiological factors and empirical definitions of 11 etiological factors. Clinical indicators analyzed in the first stage were validated clinically in patients undergoing hemodialysis. The most frequent clinical indicators were Changes in laboratory tests (100%) and daily life choices ineffective to achieve health goals (81%); and three etiological factors had a higher frequency, they are: unfavorable demographic factors (94.5%), beliefs (79%) and comorbidities (77.5%). From Latent class analysis, diagnosis prevalence was estimated at 66.28%. Clinical indicators that showed the best sensitivity measures for the nursing diagnosis Ineffective Self Health were: daily life choices ineffective to achieve health goals and Expression of difficulty with prescribed regimens. In turn, the clinical indicators of inappropriate medication use, no expression of desire to control the disease, irregular attendance to the dialysis sessions and infection were more specific as to that diagnosis. Non-adherence to treatment was the only indicator that showed confidence intervals with values for sensitivity and specificity, statistically above 0.5, being the one who has better diagnostic accuracy as the inference of the nursing diagnosis Ineffective Self Health in hemodialysis clientele. Thus, it is believed that the improvement of the components of diagnosis in question will contribute to the development of more reliable nursing interventions to the health status of the individual in hemodialysis, providing a more scientifically qualified care.

Metodologia para análise da dependabilidade de Smart Grids

Smart Grids are a new trend of electric power distribution, the future of current systems. These networks are continually being introduced in order to improve the reliability of systems, providing alternatives to energy supply and cost savings. Faced with increasing electric power grids complexity, the energy demand and the introduction of alternative sources to energy generation, all components of system require a fully integration in order to achieve high reliability and availability levels (dependability). The systematization of a Smart Grid from the Fault Tree formalism enable the quantitative evaluation of dependability of a specific scenario. In this work, a methodology for dependability evaluation of Smart Grids is proposed. A study of case is described in order to validate the proposal. With the use of this methodology, it is possible to estimate during the early design phase the reliability, availability of Smart Grid beyond to identify the critical points from the failure and repair distributions of components.

Análise wavelet em curvas de luz estelares de sistemas binários da missão espacial CoRoT

Binary systems are key environments to study the fundamental properties of stars. In this work, we analyze 99 binary systems identified by the CoRoT space mission. From the study of the phase diagrams of these systems, our sample is divided into three groups: those whose systems are characterized by the variability relative to the binary eclipses; those presenting strong modulations probably due to the presence of stellar spots on the surface of star; and those whose systems have variability associated with the expansion and contraction of the surface layers. For eclipsing binary stars, phase diagrams are used to estimate the classification in regard to their morphology, based on the study of equipotential surfaces. In this context, to determine the rotation period, and to identify the presence of active regions, and to investigate if the star exhibits or not differential rotation and study stellar pulsation, we apply the wavelet procedure. The wavelet transform has been used as a powerful tool in the treatment of a large number of problems in astrophysics. Through the wavelet transform, one can perform an analysis in time-frequency light curves rich in details that contribute significantly to the study of phenomena associated with the rotation, the magnetic activity and stellar pulsations. In this work, we apply Morlet wavelet (6th order), which offers high time and frequency resolution and obtain local (energy distribution of the signal) and global (time integration of local map) wavelet power spectra. Using the wavelet analysis, we identify thirteen systems with periodicities related to the rotational modulation, besides the beating pattern signature in the local wavelet map of five pulsating stars over the entire time span.

Análise wavelet em curvas de luz estelares de sistemas binários da missão espacial CoRoT

Binary systems are key environments to study the fundamental properties of stars. In this work, we analyze 99 binary systems identified by the CoRoT space mission. From the study of the phase diagrams of these systems, our sample is divided into three groups: those whose systems are characterized by the variability relative to the binary eclipses; those presenting strong modulations probably due to the presence of stellar spots on the surface of star; and those whose systems have variability associated with the expansion and contraction of the surface layers. For eclipsing binary stars, phase diagrams are used to estimate the classification in regard to their morphology, based on the study of equipotential surfaces. In this context, to determine the rotation period, and to identify the presence of active regions, and to investigate if the star exhibits or not differential rotation and study stellar pulsation, we apply the wavelet procedure. The wavelet transform has been used as a powerful tool in the treatment of a large number of problems in astrophysics. Through the wavelet transform, one can perform an analysis in time-frequency light curves rich in details that contribute significantly to the study of phenomena associated with the rotation, the magnetic activity and stellar pulsations. In this work, we apply Morlet wavelet (6th order), which offers high time and frequency resolution and obtain local (energy distribution of the signal) and global (time integration of local map) wavelet power spectra. Using the wavelet analysis, we identify thirteen systems with periodicities related to the rotational modulation, besides the beating pattern signature in the local wavelet map of five pulsating stars over the entire time span.

Termos de troca, preço das commodities e o crescimento brasileiro : uma análise sob o prisma da restrição externa

This study aims to investigate the relationship between terms of trade and the long-term growth of Brazilian economy, from the perspective of external constraint, between the period 1994 to 2014. For this purpose, it is based on Thirlwall's (1979) original contribution, in order to empirically test the terms of trade contribution for determining the Brazilian growth potential product equivalent with Balance of Payments equilibriun. Using cointegration method, which seeks to analyze the long-term relationship between the variables, and subdividing the period into two sub-periods, 1994-2004 and 2004-2014, we estimate and compare real and hypothetical income elasticities and predicted and observed growth rates, with and without the terms of trade, for each period. The obteined results show that the inclusion of terms of trade in the empirical procedure to test the validity of Thirlwall's Law lead to higher growth rates obtained by the model (hypothetical), for the entire period 1994-2014 and for the sub-period 2004 -2014. This "theoretical" relaxation of the external constraint, caused by the inclusion of the terms of trade in traditional Thirlwall's rule, overestimated the average real growth rate for these periods, while the traditional Thirlwall's Law - without terms of trade - has adapted better to the real behavior of Brazilian economy. Thus, despite having contributed potentially for the relaxation of external constraint on Brazilian growth, the effect of terms of trade may have been offset by the negative performance of other Balance of Payments components, as capital flows and interest, profits and dividends payments abroad.

Análise das principais variáveis na flotação industrial do complexo de mineração de Tapira - MG

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.

Caracterização mecânica da liga AlSi10Mg obtida por SLM para aplicação em componentes automóveis

Este projeto visa efetuar a caracterização mecânica da liga AlSi10Mg obtida por SLM (Fundição de Metal por Laser) para aplicação em componentes automóveis. Ao longo deste projeto é efetuada uma pesquisa bibliográfica das tecnologias de fabrico rápido mais frequentemente aplicadas ao processamento de alumínios, abordando de forma específica a tecnologia SLM, bem como a influência dos seus parâmetros no processamento de ligas de alumínio. Será levado a cabo um estudo comparativo da liga AlSi10Mg fabricada por fundição em molde permanente com a obtida por SLM, analisando-se a microestrutura das ligas, bem como as suas propriedades mecânicas, através da realização de ensaios de dureza, tração, análise dinâmico-mecânica e fadiga. Deste modo será possível perceber as diferenças entre o comportamento mecânico da liga obtida por SLM e a liga obtida pelo método convencional. Em resultado do estudo realizado, observou-se que a liga AlSi10Mg obtida por SLM apresenta uma microestrutura muito mais fina do que a liga fabricada por fundição em molde permanente, o que lhe permite ter um comportamento mecânico superior na maioria dos ensaios mecânicos realizados. Assim, é possível aplicar a tecnologia SLM ao fabrico de componentes em alumínio no sector automóvel, visto ser possível obter propriedades mecânicas superiores ou equivalentes aos componentes fabricados pelos processos de fabrico convencionais.

Centrais de Compras e de Serviços no Setor de Farmácias do Brasil: Alternativa para a Sobrevivência das Farmácias Independentes Face às Grandes Redes

No setor de farmácias brasileiro, composto por mais de 55.000 unidades, observa-se uma polarização entre as grandes cadeias, que são caracterizadas por gestão profissionalizada e escala de compra, e os varejistas independentes. As farmácias independentes encontraram no associativismo, por meio das centrais de negócios, uma alternativa para competir com as grandes redes. Esta pesquisa, realizada junto a 426 gestores de farmácias que operam em associações, identificou, por meio de análise fatorial exploratória, as principais contribuições das associações para a competitividade face às redes: atendimento; imagem da rede; compras conjuntas; nível de informação; suporte operacional e treinamento. O fator ‘compras conjuntas’, relacionado à escala de compra e que está na origem das associações em geral, figura em terceiro plano, suplantado por outros serviços supridos, o que caracteriza a evolução para o conceito das centrais de serviços. Os resultados evidenciaram que as associações possibilitam melhoria da competitividade das farmácias anteriormente independentes, segundo seus gestores.

Afinidades em redes sociais e sua relação com disposição em colaborar: análise de caso em uma pequena empresa

O objetivo central desta pesquisa foi identificar se os indivíduos que recebem maior indicação de afinidade pelos membros da rede social em que estão inseridos na empresa são aqueles considerados possuidores de maior participação colaborativa pelos gestores. O estudo foi realizado com 17 funcionários do setor produtivo de uma pequena empresa metalúrgica localizada em São Caetano do Sul - SP. Inicialmente, utilizou-se a técnica de Análise de Redes Sociais (SNA-Social Network Analysis) através do software UCINET 6.0, considerando-se o critério de afinidade. Cada funcionário indicou um nível de afinidade que possui com cada um dos demais participantes da rede. A SNA permite diversas análises das relações entre os componentes da rede úteis para os gestores, e algumas delas são mostradas neste artigo. Porém, o foco principal do trabalho foi primeiramente identificar quais indivíduos (nós da rede) recebem maior número de manifestações de afinidade (variável afinidade). Numa segunda etapa, coletou-se a percepção dos gestores do setor com relação à disposição em colaborar de cada funcionário (variável disposição em colaborar). Finalmente, utilizando o software SPSS 15, realizou-se teste estatístico onde foi verificada a existência de forte correlação entre as duas varáveis. Assim, o estudo indicou que os funcionários que recebem maior número de manifestações de afinidade dos colegas são os que têm maior disposição em colaborar, segundo os gestores da empresa. Esta constatação indica que, se os gestores buscarem formas de estimular a inserção social dos funcionários, provavelmente haverá aumento nos níveis de participação colaborativa.