Numerical analysis of the thermal energy storage in cellular structures filled with phase-change material

This paper reports the results of a numerical study on the thermal performance of metal cellular structures that can be obtained by additive manufacturing (selective laser melting) when they are impregnated with phase change material (PCM) for possible applications in electronic cooling. Two body-centered cubic (BCC) periodic structures with cell sizes of 5 mm and 10 mm and a porosity of 87%, made of two solid materials (aluminum alloy and copper), and two paraffins with characteristic melting temperatures of 55 and 64 °C were considered. The numerical simulations are carried out using the commercial code ANSYS Fluent and are based on a previously validated purely conductive heat transfer model. The computational domains include just small repetitive portions of the considered composite structures, thus allowing substantial savings of computational time. Computed results show that, with both paraffins, the copper made finer BCC structure (5 mm) yields the best thermal performances, i.e, the shortest PCM melting time and the highest rate of thermal energy storage during transients

Experimental and numerical analysis of the thermal performance of PCM-impregnated reticular structures obtained by additive manufacturing

This paper proposes a combined experimental and numerical analysis of the melting of three different paraffin waxes embedded in reticular structures fabricated by additive manufacturing. The parent material of the reticular structures is AlSi10Mg. Metal structures, having a 100 mm square base and a thickness of 20 mm, were printed between two 10 mm thick plates. Samples were positioned in an upright position and laterally heated applying different heat fluxes. Three different paraffins were tested, with different characteristic melting temperatures (42 °C, 55 °C, and 64 °C), which are suitable for electronics cooling applications. Four different structures were tested, having a cell length of 5 mm and 10 mm, and porosities of 0.87 and 0.93. Besides the experimental tests, numerical simulations of the melting phenomenon were carried out using a purely conductive model implemented in ANSYS Fluent. The discretized numerical domains represented just small repetitive portions of the test modules, thus allowing substantial computational time savings. This simplified method has been proven to yield results that are in good agreement with the experimental data. The main outcome of this work is the setup of the simplified numerical procedure, which was then validated and used to investigate the effectiveness of the considered structures in diffusing heat into the low thermal conductivity phase change materials. It was concluded that the best overall thermal performance can be obtained with low porosity and low cell size since this enables faster melting processes and better surface temperature control

Tuberculosis/HIV/AIDS coinfection in Porto Alegre, RS/Brazil - invisibility and silencing of the most affected groups

OBJECTIVE: To analyze how belonging to certain social groups contributes to constituting the vulnerabilities associated with illnesses due to tuberculosis/HIV/AIDS coinfection. METHODOLOGYThis is a qualitative study carried out in the city of Porto Alegre, state of Rio Grande do Sul, in regions of high social vulnerability. Twenty coinfected people were interviewed in specialized health services between August and December 2016. The analysis was based on the frameworks The Sound of Silence and Vulnerability and Human Rights. RESULTS: Socioeconomic conditions were decisive for the constitution of the vulnerability conditions. Processes of people invisibilization, and the silencing of their voices, in a scenario marked by economic, racial and gender inequalities, contributed for their health needs not to be understood and effectively taken into account in the services actions. FINAL CONSIDERATIONS: The more effective strategies are to legitimize voices and to understand the needs of those affected by coinfection, the greater the chances that programmatic responses to the problem will be successful

Manutenção em campo de níveis variados de palhada de cana-de-açúcar: efeitos sobre o acúmulo de nitrogênio nas plantas.

Resumo: O objetivo do trabalho foi estudar a contribuição de diferentes níveis de palhada sobre o acumulo de nitrogênio na cana-de-açúcar. O ensaio foi instalado em Araras-SP, durante as safras de 2011-12 e 2012-13 (variedade RB-845210). Foram aplicados cinco tratamentos, com níveis de 0%, 25%, 50%, 75% e 100% (0 - 2,8- 5,7- 8,5 -11,3 t ha-1 safra 2011-12) (0 - 3 - 6,2 - 9,4 - 12,8 t ha-1 safra 2012-13) dispostos em blocos ao acaso com quatro repetições. Para acompanhar o acumulo de N nos diferentes compartimentos da planta (folhas verdes, folhas secas e colmo) de cana-de-açúcar foram utilizados os dados de massa seca (kg ha-1) e concentrações de N (g kg-1) de cada um destes componentes, obtidos em biometrias realizadas ao longo dos dois ciclos de cultivos estudados. Utilizou-se a análise de variância e regressão para o tratamento estatístico dos resultados. Foi possível concluir que: a manutenção de quantidades de palhada entre 5-12 t ha-1 promovem o mesmo acúmulo de nitrogênio no colmo em relação à ausência deste resíduo (sem palhada) somente após dois ciclos de cultivo de cana-de-açúcar; sendo que no primeiro ciclo há superioridade do tratamento sem palhada apenas sobre o maior nível deste resíduo; não há uma tendência consistente para o acúmulo de nitrogênio para as folhas verdes e secas em função de diferentes aportes de palhada sobre o solo. Abstract: The aim of this study was to evaluate the contribution of different levels of straw on the accumulation of nitrogen in sugarcane. The trial was conducted at the harvests of 2011-12 and 2012-13 in Araras-SP, using the RB-845210 variety. There were tested five levels of straw (0% - 25% - 50% - 75% - 100%), related with 2,8 - 5,7 - 8,5 -11,3 t ha -1 ( 2011-12) and 3,0 ? 6,2 ? 9,4 ? 12,8 t ha -1 (2012-13), that were arranged in a randomized block design with four replications. To determine N accumulation in sugarcane there was used dry mass (kg ha -1 ) and N concentrations (g kg -1 ) of stalk, green and dry leaves, obtained by biometry evaluations realized during the two ratoons. Variance analyses and regressions were used as statistic tool. It is possible to conclude that after two cycles of sugarcane the inputs of 5-12 t ha -1 of straw by harvest has the same contribution for nitrogen stalk accumulation than traits without straw; although in the first cycle the trait without straw is superior than the higher level of this residue. About green and dry leaves there is no tendency for the nitrogen accumulation for the input of different levels of straw in soil

Local Simulation Algorithms for Coulomb Interaction

Long ranged electrostatic interactions are time consuming to calculate in molecular dynamics and Monte-Carlo simulations. We introduce an algorithmic framework for simulating charged particles which modifies the dynamics so as to allow equilibration using a local Hamiltonian. The method introduces an auxiliary field with constrained dynamics so that the equilibrium distribution is determined by the Coulomb interaction. We demonstrate the efficiency of the method by simulating a simple, charged lattice gas.Comment: Last figure changed to improve demonstration of numerical efficienc

Atypical onset as predictor of poor outcome in Pediatric Systemic Lupus Erythematosus (pSLE)

Poster Presentation

Genome sequence of the fish brain bacterium Clostridium tarantellae

Eubacterium tarantellae was originally cultivated from the brain of fish affected by twirling movements. Here, we present the draft genome sequence of E. tarantellae DSM 3997, which consists of 3,982,316 bp. Most protein-coding genes in this strain are similar to genes of Clostridium bacteria, supporting the renaming of E. tarantellae as Clostridium tarantellae