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In the past decades, combined solar energy with heat pump systems has been one of the very widespread ways to improve the efficiency of conventional heat pumps. In that way, this paper presents an experimental analysis of the influence of environmental conditions in a small size DX-SAHP operating with CO2 as refrigeration fluid to heat water. The variation of the water inlet temperature, the solar radiation flux and the relative humidity are analyzed and 88 different experimental results are presented. To support the analysis, a thermographic camera was also used. The results show that the gas cooler outlet pressure and temperature are strongly influenced by the water inlet temperature. As the water inlet temperature increases, the gas cooler outlet pressure and temperature increase, and consequently the COP decreases. The COP decreases in 45.8% for the variation of the water inlet temperature to 15–35 oC. The variation of the solar radiation of 876.9–30.17 W.m-2 presents a reduction of performance in about 30%. For the same conditions for the water heat exchange, the pressure ratio of the cycle decreases with an augment on the solar radiation flux. In addition, the COP is higher in 6% for a change in the mean relative humidity of 31.6–55.8 %.

This paper presents an experimental study on a direct-expansion solar-assisted heat pump (DX-SAHP) operating with capillary tubes in a transcritical carbon dioxide cycle. An air-solar dual-source evaporator is also proposed as an alternative to mitigate the performance drop in low solar radiation conditions. The experiments followed a factorial design, considering capillary tubes (number 1 and number 2) and operating schemes (Low Solar Radiation, Low Solar Radiation with fan, and High Solar Radiation) as factors. The results showed that altering from Low Solar Radiation (7 W/m2) to High Solar Radiation (969 W/m2) caused an augment on the heating capacity (58%), on coefficient of performance (from 2.19 to 3.12; 42%), on the refrigerant mass flow rate (35%), and on the degree of superheat (from 4.4 K to 30.6 K). Changing from Low Solar Radiation to Low Solar Radiation with fan, a 17% improvement on the heating capacity was found, with no variation on coefficient of performance. Besides the evaporating pressure, the gas cooler pressure was also sensitive to solar radiation variations. It is estimated that for lower levels of solar radiation, up to 570 W/m2, a single capillary tube could be a reasonable choice for a DX-SAHP. This work aims to be the first to experimentally investigate the use of capillary tubes in a DX-SAHP under solar radiation variations greater than 960 W/m2.

This work presents a study for examining the viability of Solar Geothermal Hybrid Source Heat Pump systems to produce domestic hot water in Brazilian-type climates. The system considered has an open-loop ground-water (aquifer) and an uncovered solar collector that can be used in a separate or connected in series topology. The refrigerant chosen for the heat pump was R290 (propane). This theoretical analysis was made using lumped models for each component of the system. The influence of ambient temperature, solar radiation, water well depth and ground water temperature in the COP, payback and collector efficiency were analyzed. The results showed that the COP of a Hybrid Source Heat Pump was better than other types of heat pump configurations for most environmental conditions, but the best payback was obtained using a Solar-Assisted Heat Pump. A case of study was performed for three different cities in Brazil and the paybacks found were in the range of 2.28 and 4.45 years. The results of COP and payback were compared with other papers and the maximum difference was 10% and 12%, respectively. Considering the scenario of a house that already has a water well, thereby eliminating the drilling cost, the best payback is obtained using a Ground-Source Heat Pump.

The present work aimed to prepare and characterize carbon nanotube (CNT) buckypapers (BPs) and to provide a perspective on possible applications in the optical device industry and power generation through triboelectric nanogenerators. The CNTs were dispersed in aqueous solution with the aid of a dispersing agent and then vacuum filtered. The prepared buckypaper has low average optical reflectance and shows an improvement in electrical conductivity and power generation when silver nanowires were added. This material includes new horizons and future applications for carbon nanotube buckypapers,including aerospace applications.

The availability of large-scale face datasets has been key in the progress of face recognition. However, due to licensing issues or copyright infringement, some datasets are not available anymore (e.g. MS-Celeb-1M). Recent advances in Generative Adversarial Networks (GANs), to synthesize realistic face images, provide a pathway to replace real datasets by synthetic datasets, both to train and benchmark face recognition (FR) systems. The work presented in this paper provides a study on benchmarking FR systems using a synthetic dataset. First, we introduce the proposed methodology to generate a synthetic dataset, without the need for human intervention, by exploiting the latent structure of a StyleGAN2 model with multiple controlled factors of variation. Then, we confirm that (i) the generated synthetic identities are not data subjects from the GAN's training dataset, which is verified on a synthetic dataset with 10K+ identities; (ii) benchmarking results on the synthetic dataset are a good substitution, often providing error rates and system ranking similar to the benchmarking on the real dataset., 11 pages, Accepted for publication in the 2021 International Joint Conference on Biometrics (IJCB 2021)

One option to reduce the energy consumption to produce domestic hot water is to replace the electrical heaters by direct expansion solar assisted heat pumps. Although, there are many studies on the performance of this system, there are few studies on economic analysis of the equipment. In this paper, an economic analysis comparing the payback of heat pump over an electrical heater is carried out. The heat pump is modeled using lumped models for heat exchangers and a black box model for the compressor. The results show that the augment of collector size increases the COP, but it decreases the collector efficiency. The economic analysis showed that there is a collector size that minimizes the payback time. Additionally, the influence of the environmental conditions, the refrigerant, the costs and the heating capacity on the payback period and optimum collector size were investigated. The results showed that there is an economically optimum size of collector area for the DX-SAHP, which it is the same for different environmental conditions. A case study was made for three different cities and the payback time found is the range of 1.77–3.24 years.

The task of Heterogeneous Face Recognition consists in matching face images that are sensed in different domains, such as sketches to photographs (visual spectra images), and thermal images to photographs or near-infrared images to photographs. In this paper, we suggest that the high-level features of Deep Convolutional Neural Networks trained in visual spectra images are potentially domain independent and can be used to encode faces sensed in different image domains. A generic framework for Heterogeneous Face Recognition is proposed by adapting Deep Convolutional Neural Networks low-level features in, so-called, Domain Specific Units. The adaptation using the Domain Specific Units allows the learning of shallow feature detectors specific for each new image domain. Furthermore, it handles its transformation to a generic face space shared between all image domains. Experiments carried out with four different face databases covering three different image domains show substantial improvements, in terms of recognition rate, surpassing the state-of-the-art for most of them. This work is made reproducible: all the source code, scores, and trained models of this approach are made publicly available.

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Objetivo: Identificar o perfil epidemiológico dos óbitos por sepse neonatal no estado da Bahia. Métodos: Estudo ecológico exploratório descritivo de série temporal, realizado através dos dados secundários do Sistema de Informação sobre Mortalidade (SIM). Foram estudados os óbitos por sepse neonatal ocorridos entre os anos de 2014 e 2018, entre indivíduos de 0 a 27 dias de nascido, residentes do Estado da Bahia. Baseou-se nas categorias da CID-10: A40, A41 e P36. Foram estudados varáveis ​​neonatais, de óbito, da gestação, do parto e maternas. Resultados: Ocorreram 1114 óbitos neonatais por sepse, representando 9,4% de todas as mortes entre faixa etária estudada no período, obtendo uma taxa de 1,09 óbitos por cada 1.000 nascidos vivos. Sendo caracterizados por bebês entre a faixa etária entre 0 a 6 dias de vida, recém-nascido do sexo masculino, cor parda, aqueles com extremo baixo peso e prematuros de idade gestacional de 22 a 31 semanas. Houve domínio também entre aqueles que nasceram de gravidez unifetal, parto vaginal, de mães entre a faixa etária de 15 a 24 anos com escolaridade 8 a 11 anos. Conclusão: Os neonatos constituem um grupo mais vulnerável à sepse, aumentando o risco de mortalidade. Os resultados encontrados indicam necessidade de intensificação nas medidas de prevenção.

A adequada utilização da energia é conteúdo fundamental para a formação de uma sociedade detentora de uma consciência ecológica e praticante de atos responsáveis que visem o consumo eficiente dos recursos naturais. Nesta temática foi desenvolvido o projeto de extensão Energia para Todos, através de uma equipe multidisciplinar, atuando em uma escola de Contagem – MG. Os trabalhos foram desenvolvidos por meio de oficinas com temas relacionados à energia. Os resultados foram aferidos através de questionários e atividades realizadas pelos alunos. O envolvimento e a qualidade das soluções propostas pelos alunos nos trabalhos demonstram o êxito da metodologia aplicada.

FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais Providing adequate and low-cost control is an important step in the use of direct expansion solar assisted heat pump (DX-SAHP) in replacement of the electric showers in the Brazilian residences. In that way, design a low-cost controller to regulate the hot water temperature in 60°C (to storage) and 45°C (to direct consumption) is the first goal of this study. Experimental tests demonstrated the capacity of the control system to keep hot water in the correct temperature in different environment and system conditions. The second goal of this study is to evaluate the expansion valve opening. The impact of a fixed aperture in the functioning and on the performance of these systems is not well known, especially for small-size systems. In this context, it is presented an experimental analysis of the influence of the expansion valve opening on the performance of a carbon dioxide (CO2) DX-SAHP. Experimental tests were carried out considering solar radiations about 48 W/m² and 715 W/m² in which the coefficient of performance (COP) observed were 2.21 and 2.58, respectively. The value of the expansion device opening that leads to the maximum COP was similar, regardless the solar radiation. In consequence, for a small CO2 DX-SAHP, using a basic cycle configuration (where the expansion device is used to control the optimum high pressure and consequently the COP), a low-cost embedded system water temperature control and a static expansion device would be suitable for proper control. Finally, the third goal of this study is to evaluate the effects of the sudden variations in the solar radiation on the superheat. The mathematical model was validated using experimental data and employed to perform several simulations. The results obtained with the mathematical model revealed that a small variation of the solar radiation leads to a significant variation in the superheat, therefore requiring an immediate action of the expansion device. In conclusion, an electronic expansion valve would be better suited to meet the needs of rapid interventions on the mass flow rate at the evaporator inlet and also the DX-SAHP could operate in a continuous transient condition in some seasons. Prover controle adequado e de baixo custo é uma importante etapa no processo de uso da bomba de calor de expansão direta assistida por energia solar (DX-SAHP) em substituição aos chuveiros elétricos nas residências brasileiras. Neste sentido, projetar um controlador de baixo custo para regular a temperatura de água quente em 60°C (armazenamento) e 45°C (consumo direto) é o primeiro objetivo deste trabalho. Testes experimentais mostraram a capacidade do controlador em manter, em diferentes condições ambientais e de operação, a temperatura da água quente no valor desejado. O segundo objetivo deste estudo é avaliar a área de abertura do dispositivo de expansão. Os efeitos da manutenção de uma abertura fixa para o dispositivo de expansão no funcionamento e no desempenho do sistema, sobretudo os de pequeno porte, não são bem conhecidos. Neste contexto, é realizada uma análise experimental da influência da abertura do dispositivo de expansão no desempenho de uma CO2 DX-SAHP. Experimentos foram realizados com radiações próximas a 48 W/m² e 715 W/m², resultando em coeficiente de performance (COP) iguais a 2,21 e 2,58 respectivamente. Observou-se que a abertura do dispositivo de expansão para a qual obtevese o COP máximo foi similar independente da radiação solar. Em consequência, para uma CO2 DX-SAHP de pequeno porte, operando em uma configuração de ciclo básico (na qual o dispositivo de expansão é utilizado para controlar a pressão de alta ótima e consequentemente o COP), um sistema embarcado de baixo custo para controle da temperatura de água e um dispositivo de expansão estático podem proporcionar um controle adequado. Finalmente, o terceiro objetivo deste estudo é avaliar os efeitos de uma variação repentina da radiação solar no grau de superaquecimento. Dados experimentais foram utilizados para validação do modelo. Após validação, o modelo foi utilizado para realizar diversas simulações. Os resultados mostraram que uma pequena variação na radiação solar produz uma variação significativa no grau de superaquecimento, demandando uma ação imediata do dispositivo de expansão. Conclui-se então, que uma válvula de expansão eletrônica poderia ser o dispositivo de expansão mais indicado para regular a vazão mássica de CO2 na entrada do evaporador. Ressaltando-se que ainda, a operação em continuo regime transiente em algumas estações do ano reforça a indicação da válvula eletrônica.

CAPES Com a tendência de aprofundamento cada vez maior de minerações subterrâneas ao longo dos anos, a simulação numérica via métodos dos elementos finitos aplicados a problemas de mecânica de rocha tem sido cada vez mais utilizada. Estudos em mecânica de rochas são extremamente importantes para o desenvolvimento de uma lavra segura e otimizada do ponto de vista produtivo. O aumento da produtividade do método de lavra VRM (Vertical Retreat Mining) ou Lavra em Recuo Vertical e a necessidade de estudos mais completos sobre a abertura desses realces do ponto de vista estrutural vem a corroborar para essa demanda. A importância do entendimento das tensões cisalhantes, deformações plásticas e variação em parâmetros de resistência é a base para uma operação segura e otimizada na frente de lavra. A estabilidade das escavações em rochas é uma área de estudo da mecânica das rochas tornando-se fundamental para a mineração. Nesse contexto a Mineração Caraíba S/A, através do seu corpo técnico, nos forneceu parâmetros constitutivos reais para a realização da simulação numérica. O presente trabalho tem como objetivo realizar simulação geomecânica de realces abertos em uma mineração de cobre, com diferentes configurações dos materiais de preenchimento desses realces,utilizando o método de elementos finitos onde abordaremos processos de deformação plástica, tensões totais cisalhantes, deslocamentos verticais e horizontais e variação de parâmetros de resistência no entorno das escavações preenchidas ou não. Desta forma, elaborou-se um cenário a princípio com geometria bem definida, porém com parâmetros constitutivos da rocha reais com o intuito de fundamentação do caso para em seguida analisar o caso totalmente real com geometria fornecida pela própria empresa. Foi empregado o código de elementos finitos CODE_BRIGHT utilizando um modelo elastoplástico de Mohr-Coulomb com regularização viscosa de Perzyna. A geometria dos cenários e a geração das malhas foram realizadas no software GMSH onde, em seguida, já com meu domínio discretizado,é utilizado um código em ambiente MatLab para geração dos arquivos de entrada do CODE_BRIGHT, para ao final interpretar nossos arquivos de saída no GID onde, observações sobre deformações plásticas, tensões totais cisalhantes, perda de parâmetros de resistência e deslocamentos serão analisados juntamente com a eficiência dos processos de enchimento dos realces diante do processo de lavra. With the trend of increasing deepening of underground mining over the years the numerical simulation using finite element methods applied problems of rock mechanics has been increasingly used. Studies in rock mechanics are extremely important for the development of a safe and optimally productive field of view. With the increase of the productivity of the Vertical Retreat Mining (VRM) method and Vertical Retreat Mining, the need for more complete studies on the opening of these structural enhancements corroborates this demand. The importance of understanding the shear stresses, plastic deformations and variation in resistance parameters is the basis for a safe and optimized operation at the mining front. The stability of rock excavations is an area of study of rock mechanics making it fundamental for mining. In this context, Mineração Caraíba S / A, through its technical staff, provided us with real constitutive parameters to perform numerical simulation. The present work has the objective of performing geomechanical simulation of open highlights in a copper mining, with different configurations of the fill materials of these enhancements, using the finite element method, where we will discuss plastic deformation processes, shear stresses, vertical and horizontal displacements and variation of resistance parameters in the vicinity of the filled or unfilled excavations. In this way, a scenario was elaborated at first with a well-defined geometry, but with real constituent parameters of the rock with the intention of fudamentation of the case to next analyze the totally real case with geoemtria provided by the company itself. The CODE_BRIGHT finite element code was used using an elasto-plastic Mohr-Coulomb model with viscous Perzyna regularization. The geometry of the scenarios and the generation of the meshes were carried out in the GMSH software, and then, with my discretized domain, a code is used in MatLab environment to generate the input files of CODE_BRIGHT, in order to interpret our output files in the GID where observations on plastic deformations, total shear stresses, loss of resistance parameters and displacements will be analyzed together with the efficiency of the filling processes of the enhancements before the mining process.

An important step during a project of a heat pump system is choosing a more suitable refrigerant. This paper presents a comparative study among refrigerants for a small direct expansion solar assisted heat pump (DX-SAHP). The mathematical model used in this study is presented in detail and validated from an experimental setup. The R134a is the reference and the refrigerants with low GWP are R290, R600a, R744 and R1234yf. The results show that R290 has better COP than others refrigerants for solar radiation between 300 W/m2 and 700 W/m2, as well as for environment temperature between 10 ° C and 35 ° C. On the other hand, for solar radiation less than 50 W/m2, the R134a has better COP than R290. TEWI (Total Equivalent Warming Impact) analysis indicates that the indirect emission is the most important effect, and then, the TEWI results almost followed the COP outcome. A parametric analysis was conducted to evaluate the influence of the CO2 emission factor for producing electricity. In countries with higher emission factor, the refrigerant with the best COP has the best TEWI. The influence of wind speed and ambient temperature in COP of a DX-SAHP using R290 were more relevant in low solar radiation.