Machine Learning Algorithms for Flow Pattern Classification in Pulsating Heat Pipes

Owing to their simple construction, cost effectiveness, and high thermal efficiency, pulsating heat pipes (PHPs) are growing in popularity as cooling devices for electronic equipment. While PHPs can be very resilient as passive cooling systems, their operation relies on the establishment and persistence of slug/plug flow as the dominant flow regime. It is, therefore, paramount to predict the flow regime accurately as a function of various operating parameters and design geometry. Flow pattern maps that capture flow regimes as a function of nondimensional numbers (e.g., Froude, Weber, and Bond numbers) have been proposed in the literature. However, the prediction of flow patterns based on deterministic models is a challenging task that relies on the ability of explaining the very complex underlying phenomena or the ability to measure parameters, such as the bubble acceleration, which are very difficult to know beforehand. In contrast, machine learning algorithms require limited a priori knowledge of the system and offer an alternative approach for classifying flow regimes. In this work, experimental data collected for two working fluids (ethanol and FC-72) in a PHP at different gravity and power input levels, were used to train three different classification algorithms (namely K-nearest neighbors, random forest, and multilayer perceptron). The data were previously labeled via visual classification using the experimental results. A comparison of the resulting classification accuracy was carried out via confusion matrices and calculation of accuracy scores. The algorithm presenting the highest classification performance was selected for the development of a flow pattern map, which accurately indicated the flow pattern transition boundaries between slug/plug and annular flows. Results indicate that, once experimental data are available, the proposed machine learning approach could help in reducing the uncertainty in the classification of flow patterns and improve the predictions of the flow regimes

Valorização da ciência em tempos conturbados: Os perigos do negacionismo das mudanças climáticas para o Brasil

Neste artigo de opinião aborda-se o tema de mudanças climáticas e desastres naturais, temas muito queridos por mim e nos quais eu trabalho por mais de 30 anos. Nos somos testemunhas como a ciência, o meio ambiente e a educação estão sendo tratados de uma forma que até parece que estamos regredindo para os tempos das trevas na idade média. Se questiona que a terra seja redonda e não plana, se questiona a teoria da evolução das espécies, se questiona o aquecimento global e ação humana na mudança de clima. Assistimos a tragédias ambientas tais como as secas e queimadas na Amazônia e Pantanal, as crises hídricas no Sudeste e Sul do Brasil, as enxurradas e deslizamentos de terra devido a chuvas intensas em Petrópolis, Angra dos Reis, Paraty em 2022 e em outras regiões e tempos que mataram centos de pessoas, vítimas inocentes do descaso dos governos locais que permitiram a construção de moradias em áreas de risco de desastres. Lembremos também as tragédias de Brumadinho e Mariana, desastres tecnológicos motivados pela cobiça de grandes empresas mineradoras onde lucro é mais importante que a segurança dos seus trabalhadores

Valorização da ciência em tempos conturbados

Neste artigo de opinião aborda-se o tema de mudanças climáticas e desastres naturais, temas muito queridos por mim e nos quais eu trabalho por mais de 30 anos. Nos somos testemunhas como a ciência, o meio ambiente e a educação estão sendo tratados de uma forma que até parece que estamos regredindo para os tempos das trevas na idade média. Se questiona que a terra seja redonda e não plana, se questiona a teoria da evolução das espécies, se questiona o aquecimento global e ação humana na mudança de clima. Assistimos a tragédias ambientas tais como as secas e queimadas na Amazônia e Pantanal, as crises hídricas no Sudeste e Sul do Brasil, as enxurradas e deslizamentos de terra devido a chuvas intensas em Petrópolis, Angra dos Reis, Paraty em 2022 e em outras regiões e tempos que mataram centos de pessoas, vítimas inocentes do descaso dos governos locais que permitiram a construção de moradias em áreas de risco de desastres. Lembremos também as tragédias de Brumadinho e Mariana, desastres tecnológicos motivados pela cobiça de grandes empresas mineradoras onde lucro é mais importante que a segurança dos seus trabalhadores

Crise Hídrica em São Paulo em 2014: Seca e Desmatamento

O presente estudo apresenta uma análise hidrometeorológica da estação chuvosa 2013/2014 na Região Sudeste do Brasil, com o objetivo de diagnosticar a seca e seu impacto na disponibilidade hídrica do Estado de São Paulo. Foram analisados os totais acumulados da precipitação, os principais sistemas meteorológicos atuantes durante o período chuvoso (dezembro-fevereiro) e o papel da floresta Amazônica como uma das fontes de umidade para o Brasil Central e regiões sul-sudeste. As análises revelaram que os totais acumulados foram significativamente abaixo dos valores médios, com desvios negativos em torno de 62%, temperaturas 2.5 oC acima da média e um aumento no consumo de água, esses fatores conjuntamente geraram uma crise hídrica sem precedente desde 1960.    This study shows an hydrometeorological analyses of the 2013-2014 rainy season in Southeastern Brazil, in order to assess the magnitude and extension of the drought and water crises that affect the State of Sao Paulo during summer of 2014. For that we analyze mean rainfall and anomalies during the peak rainfall months (December-February). In particular, rainfall was well below normal from December 2013 to February 2014. We investigate the physical causes of this lack of rain in the region, in the context of rain producing mechanisms in the region, including the role of the Amazon tropical rainforest as one of the sources or moisture for rainfall in Southern and Southeastern Brazil. Rainfall analyses showed that summertime accumulated were about 62% below normal in 2014, and together with a 2,5 oC warmer summer and increase in water use, all of these generated an unprecedented water crisis since 1960.

Impact of soil moisture over Palmer Drought Severity Index and its future projections in Brazil Avaliação da umidade do solo e do Índice de Severidade de Seca de Palmer no Brasil e suas projeções futuras

Soil moisture is a main factor for the study of drought impacts on vegetation. Drought is a regional phenomenon and affects the food security more than any other natural disaster. Currently, the monitoring of different types of drought is based on indexes that standardize in temporal and regional level allowing, thus, comparison of water conditions in different areas. Therefore, in order to assess the impact of soil moisture during periods of drought, drought Palmer Severity Index was estimated for the entire region of the territory. For this were used meteorological data (rainfall and evapotranspiration) and soil (field capacity, permanent wilting point and water storage in the soil). The data field capacity and wilting point were obtained from the physical properties of soil; while the water storage in soil was calculated considering the water balance model. The results of the PSDI were evaluated during the years 2000 to 2015, which correspond to periods with and without occurrence of drought. In order to assess the future drought projections, considering the set of the Coupled Model Intercomparison rainfall data Project Phase 5 (CMIP5). Climate projections precipitation in CMIP5 for the period 2071-2100 was extracted generating entitled forcing scenarios Representative Concentration Pathways - RCPs, and referred to as RCOP 8.5, corresponding to an approximate radiative forcing the end the twenty-first century of 8.5 Wm-2. The results showed that the PDSI is directly associated with climatological patterns of precipitation and soil moisture in any spatial and temporal scale (including future projections). Therefore, it is concluded that the PDSI is an important index to assess soil moisture different water conditions, as well as the association with economic and social information to create risk maps for subsidies to decision makers.Peer ReviewedPostprint (published version

Investigación de Salmonella sp. por el método de aglutinación rápida en placa (ARP) en lotes de gallinas en recría y postura en el norte de la provincia de La Pampa

In the present work a serologic survey in rearing hens and layer hens, older than twelve weeks of age, was carried out with the purpose of determinig prevalent antibodies against Salmonella sp. The study was fulfilled in the departaments Capital, Conhelo, Chapaleufú and Maracó of the Province of La Pampa, by means of the PQA technique, finding in such studies that the prevalence for the infection in the group of layer hens is of 5.9% and in the rearing hens is of 3%En el presente trabajo se realizó una encuesta serológica en gallinas (Gallus gallus domesticus) para postura y recría, mayores de 12 semanas de edad con la finalidad de determinar anticuerpos prevalentes contra Salmonella sp. El estudio se llevó a cabo en los departamentos Capital, Conhelo, Chapaleufú y Maracó de la provincia de La Pampa, mediante la técnica de ARP, encontrándose en los mismos que la prevalencia para esta infección en este grupo de aves en postura es del 5.9% y en los lotes de recría es de 3

Construindo fichas terminológicas para estudos sócio-históricos

  This article presents an excerpt from the research results of Teixeira (2021) in which we used the precepts of Sociocognitive Terminology with the aim of producing a terminological record with a diachronic bias in order to support the composition of entries for a glossary of medico-legal terms present in corpus delicti records of criminal processes of deflowering, which occurred in Sergipe in the 19th century. Our corpus is made up of 45 forensic examinations, with a time span between 1854, the year of the first document found in the Archive of the State's Judicial Power, and 1900. Our theoretical foundation is Sociocognitive Terminology (TEMMERMAN, 2000a, 2000b, 2000c) and diachronic Socioterminology (MARENGO, 2016, 2022), as we recognize terms as units of knowledge that must be studied in their textual and socio-historical context. The term deflowering is chosen to exemplify our proposed terminology sheet.Este artigo apresenta um recorte do resultado da pesquisa de Teixeira (2021) na qual utilizamos os preceitos da Terminologia Sociocognitiva com o objetivo de produzir uma ficha terminológica com viés diacrônico de forma a dar sustentação para composição de verbetes para um glossário de termos médico-legais presentes em autos de corpo de delito de processos-crime de defloramento, ocorridos em Sergipe no século XIX. Nosso corpus é composto por 45 exames de corpo de delito, com o lapso temporal compreendido entre 1854, ano do primeiro documento encontrado no Arquivo do Poder Judiciário do Estado, e 1900. Nosso alicerce teórico é a Terminologia Sociocognitiva (TEMMERMAN, 2000a, 2000b, 2000c) e a Socioterminologia diacrônica (MARENGO, 2016, 2022), pois reconhecemos os termos como unidades de conhecimento que devem ser estudadas em seu contexto textual e sócio-histórico. O termo defloramento é o escolhido para exemplificar nossa proposta de ficha terminológica

Traumatic subarachnoid pleural fistula in children: Case report, algorithm and classification proposal

Subarachnoid pleural fistulas are rare. They have been described as complications of thoracic surgery, penetrating injuries and spinal surgery, among others. We present the case of a 3-year-old female child, who suffer spinal cord trauma secondary to a car accident, developing a posterior subarachnoid pleural fistula. To our knowledge this is the first reported case of a pediatric patient with subarachnoid pleural fistula resulting from closed trauma, requiring intensive multimodal management. We also present a management algorithm and a proposed classification. The diagnosis of this pathology is difficult when not associated with neurological deficit. A high degree of suspicion, multidisciplinary management and timely surgical intervention allow optimal management