Co-Heating method for thermal performance evaluation of closed refrigerated display cabinets

In this study, an application of the adapted Co-Heating methodology for thermal performance evaluation of closed refrigerated display cabinets (RDCs) has been presented. A novel test series comprising three experiments has been developed and demonstrated on a commercial RDC with four doors to evaluate the envelope heat transfer coefficient, thermal inertia, infiltration at idle state and dynamic infiltration caused by door operations. The latter two experiments were conducted in parallel with the condensate collection method for validation of the results for infiltration. It was concluded with good (<10%) conformance between the methods that the infiltration at idle state for the tested RDC is approximately 0.022kg/s and that one 15s door opening causes approximately 0.94kg of ambient indoor air to infiltrate. Additionally, the time, equipment and associated costs for running the tests were compared, and it was concluded that the adapted Co-Heating methodology could substitute the condensate collection method for the evaluation of infiltration while providing additional results on the thermal performance

Hygro-thermal model for estimation of demand response flexibility of closed refrigerated display cabinets

In this article we present and validate a novel methodology for estimating the temperature development and heat extraction demand of closed refrigerated display cabinets (RDCs) in operating conditions, for near-future prediction and optimisation in smart grids. The approach is based on an in-house developed hygro-thermal model of an RDC, in which the conditions in each of the three main calculation domains, representing the internal air, heat exchanger and interior, are estimated at a temporal scale of seconds. The interior air temperature, heat extraction rate and run-off condensate were validated towards experimental data with good conformity. Moreover, for demand response purposes, in this article, we provide examples of how the model can be used to evaluate the temporal flexibility in heat extraction demand of RDCs. In a hypothetical supermarket with 11 RDCs exposed to various thermal loads and customer interactions, it is estimated that the heat extraction demand could be reduced to 0 for up to 83∕127 s during opening/non-opening hours respectively. With a strategic pre-cooling, the latter time could be extended to 322 s. For the case of a demand response signal requesting the supermarket to absorb excess energy, all RDCs would be able to run at full power for up to 17∕29 s, and approximately half of them for additional 20 s during opening hours. These findings are based on a total of 44 five-minutes-ahead simulations of possible scenarios for the 11 RDCs, all calculated by the presented model in approximately 10 s. In conclusion, the model provides fast and reliable results for real-time predictions in refrigeration control systems either for the benefit of the electrical grid by demand response or for energy efficiency purposes

Exploratory investigation of return air temperature sensor measurement errors in refrigerated display cabinets

By introducing doors on refrigerated display cabinets, the energy demand is substantially decreased. However, there exist significant discrepancies in temperature readings between visually identical refrigerated display cabinets equipped with doors. This study explores the cause and consequences of these differences. The exploratory methodology used within the study has used CFD simulations combined with laboratory experiments to conclude that there exists a thermal gradient in the area of the return air temperature sensor causing these discrepancies to occur. Thus, the temperature sensors position within the thermal gradient affects the perceived temperature of the control system and thereby the refrigeration strategy adopted by it. To follow up on the consequences of this observed issue, two field studies were performed to investigate the effects and occurrence of temperature sensors within the thermal gradient. Through this, it was concluded that by moving the return air sensors away from the thermal gradient, the refrigerated display cabinets were performing more uniformly as well as with a reduced heat extraction demand. Additionally, from the field study investigating the occurrence, it was found that 80.5% of the 221 reviewed refrigerated display cabinets had sensors placed in a zone where a thermal gradient exists

The multiphysics modeling of heat and moisture induced stress and strain of historic building materials and artefacts

The basic structure of historic sites and their associated interior artefacts can be damaged or even destroyed by climate change. The evaluation of combined heat and moisture induced stress and strain (HMSS) can predict possible damage-related processes. In this paper, the development of one- and two-dimensional HMSS models of building materials and artefacts in COMSOL Multiphysics Version 4, a commercial finite element software, is presented. The validation of the numerical models is revealed using analytical, numerical and experimental solutions. As a result, the HMSS model was shown to be an adequate predictive tool to determine possible damage-related processes in building assemblies and artefacts

Diagnostic potential of near-infrared Raman spectroscopy in the stomach: differentiating dysplasia from normal tissue

Raman spectroscopy is a molecular vibrational spectroscopic technique that is capable of optically probing the biomolecular changes associated with diseased transformation. The purpose of this study was to explore near-infrared (NIR) Raman spectroscopy for identifying dysplasia from normal gastric mucosa tissue. A rapid-acquisition dispersive-type NIR Raman system was utilised for tissue Raman spectroscopic measurements at 785 nm laser excitation. A total of 76 gastric tissue samples obtained from 44 patients who underwent endoscopy investigation or gastrectomy operation were used in this study. The histopathological examinations showed that 55 tissue specimens were normal and 21 were dysplasia. Both the empirical approach and multivariate statistical techniques, including principal components analysis (PCA), and linear discriminant analysis (LDA), together with the leave-one-sample-out cross-validation method, were employed to develop effective diagnostic algorithms for classification of Raman spectra between normal and dysplastic gastric tissues. High-quality Raman spectra in the range of 800–1800 cm−1 can be acquired from gastric tissue within 5 s. There are specific spectral differences in Raman spectra between normal and dysplasia tissue, particularly in the spectral ranges of 1200–1500 cm−1 and 1600–1800 cm−1, which contained signals related to amide III and amide I of proteins, CH3CH2 twisting of proteins/nucleic acids, and the C=C stretching mode of phospholipids, respectively. The empirical diagnostic algorithm based on the ratio of the Raman peak intensity at 875 cm−1 to the peak intensity at 1450 cm−1 gave the diagnostic sensitivity of 85.7% and specificity of 80.0%, whereas the diagnostic algorithms based on PCA-LDA yielded the diagnostic sensitivity of 95.2% and specificity 90.9% for separating dysplasia from normal gastric tissue. Receiver operating characteristic (ROC) curves further confirmed that the most effective diagnostic algorithm can be derived from the PCA-LDA technique. Therefore, NIR Raman spectroscopy in conjunction with multivariate statistical technique has potential for rapid diagnosis of dysplasia in the stomach based on the optical evaluation of spectral features of biomolecules

Alunos com paralisia cerebral na escola: linguagem, comunicação alternativa e processos comunicativos

O estudo assume como problema de investigação analisar as contribuições da Comunicação Alternativa e Ampliada (CAA) aos processos comunicativos de alunos sem fala articulada no contexto da escola, destacando nesses processos o papel potencializador dos interlocutores. Fundamenta-se na abordagem de linguagem e na noção de enunciado discutidas por Bakhtin e nas contribuições de Vigotski sobre a relação entre desenvolvimento e aprendizagem, postulando que a aquisição e o desenvolvimento da linguagem ocorrem no curso das aprendizagens, ao longo da vida. As análises e reflexões empreendidas evidenciam uma discussão acerca da linguagem que se desloca da dimensão orgânica para a dimensão da constituição do sujeito como humano. Sob essa visão, outros conceitos, como os de língua, fala, interação verbal, dialogia, enunciação, aprendizagem e desenvolvimento são problematizados e também considerados como elementos fundantes e presentes nas relações comunicativas entre os sujeitos sem fala articulada e seus interlocutores. Na primeira etapa, o estudo busca conhecer as formas organizativo-pedagógicas de cinco Secretarias Municipais de Educação da Região Metropolitana de Vitória e da Secretaria de Estado da Educação no que diz respeito à identificação dos alunos com Paralisia Cerebral, sem fala articulada, ao acompanhamento técnico-pedagógico e à formação de professores que atuam na Educação Especial. Na segunda etapa, objetiva conhecer a processualidade da organização do trabalho pedagógico instituída nos contextos escolares e investiga os processos comunicativos em/com dois alunos com severos comprometimentos motores e de fala em duas escolas de Ensino Fundamental, localizadas no município de Serra e de Vitória. Nesta etapa, opta pela pesquisa-ação colaborativo-crítica por contribuir, teórica e metodologicamente, para sustentar os fazeres individuais e coletivos nos lócus de investigação. Os resultados revelam que, institucionalmente, ainda não se conhece quem são e quantos são os alunos com Paralisia Cerebral sem fala articulada no contexto de suas reais necessidades. Esse desconhecimento é atribuído pelas gestoras das Secretarias Municipais de Educação investigadas ao considerarem que, via de regra, são tomadas apenas as informações do Educacenso-INEP. As identificações pontuais, quando ocorrem, são decorrentes de estratégias internas adotadas, sendo uma delas o assessoramento pedagógico das equipes às escolas. No que tange ao ensino, à aprendizagem e à avaliação, o estudo constata que são atravessados por concepções equivocadas sobre os sujeitos com Paralisia Cerebral sustentadas, sobretudo, pela baixa expectativa e pelo pouco esforço quanto à sua escolarização. Constata também que o uso dos recursos de CAA potencializa os processos comunicativos dos alunos investigados e, movimentados pela linguagem, possibilita-lhes enunciar e fixar posições, opiniões e decisões, assegurando-lhes mais autonomia e fluidez do processo comunicacional. As formas de mediação dos interlocutores assim como as dinâmicas dialógicas por eles utilizadas com os alunos se constituem como elementos importantes nos processos de comunicação e interação. A espera do outro, o apoio e o incentivo à reformulação daquilo que se quer expressar, as modificações e alterações no jogo dialógico são exemplos dessa mediação. Quanto às ações de reorganização do trabalho pedagógico, o estudo registra maior articulação e colaboração entre professores da classe, professora da Educação Especial e estagiária no planejamento das aulas, dos conteúdos, com a inserção no notebook para um dos alunos; o uso das pranchas de comunicação, por ambos os alunos e seus interlocutores, como ação inovadora nos contextos escolares; a realização de atividades pelos alunos, com gradativa autonomia, a partir da disponibilização de recursos de TA/CAA (pasta de conteúdos temáticos, figuras imantadas, quadro metálico, ponteira, plano inclinado, notebook); a proposição de ações intencionais de alfabetização, a partir da reorganização de espaços-tempos no cotidiano da escola. Conclui que as discussões teóricas e práticas das questões relacionadas com a linguagem, com os processos cognitivos e com o uso de recursos de TA/CAA alavancam mudanças na concepção dos profissionais das escolas pesquisadas que, ainda, sob uma visão reducionista quanto às formas de comunicação e de interação verbal, impõem limites à escolarização dos alunos com deficiência

One more general method for solving Oseen's equations

In this paper we have proposed a new method for solving the Oseen's equations. It has been testified in the case of the normal flow around the cylinder for the Re number being much smaller than 1. The step forward was to generalize this problem and find out the solution in the case of the oblique flow around the cylinder. We have also applied the method to treat the normal flow around the cylinder in the range of Re numbers comparable to unity. The obtained coefficients of the resistance have also been presented in the figures at the end of the paper