1 Abstract-Research and optimisation of cooling of electronic components using heat sinks becomes increasingly important in modern industry. Numerical methods with experimental realworld verification are the main tools to evaluate efficiency of heat sinks or heat sink systems. Here the investigation of relatively simple heat sink application is performed using modelling based on finite element method, and also the potential of such analysis was demonstrated by real-world measurements and comparing obtained results. Thermal modelling was accomplished using finite element analysis software COMSOL and thermo-imaging camera was used to measure the thermal field distribution. Ideas for future research involving improvement of the experimental setup and modelling verification are given.Index Terms-Finite Element Method, heat sinks, temperature measurement.
BackgroundThere is considerable information on the methylation of the promoter regions of different genes involved in gastric carcinogenesis. However, there is a lack of information on how this epigenetic process differs in tumors originating at different sites in the stomach.The aim of this study is to assess the methylation profiles of the MLH1, MGMT, and DAPK-1 genes in cancerous tissues from different stomach sites.MethodsSamples were acquired from 81 patients suffering stomach adenocarcinoma who underwent surgery for gastric cancer in the Lithuanian University of Health Sciences Hospital Kaunas Clinics in 2009–2012. Gene methylation was investigated with methylation-specific PCR. The study was approved by the Lithuanian Biomedical Research Ethics Committee.ResultsThe frequencies of methylation in cancerous tissues from the upper, middle, and lower thirds of the stomach were 11.1, 23.1, and 45.4 %, respectively, for MLH1; 22.2, 30.8, and 57.6 %, respectively, for MGMT; and 44.4, 48.7, and 51.5 %, respectively, for DAPK-1. MLH1 and MGMT methylation was observed more often in the lower third of the stomach than in the upper third (p < 0.05). In the middle third, DAPK-1 promoter methylation was related to more-advanced disease in the lymph nodes (N2–3 compared with N0–1 [p = 0.02]) and advanced tumor stage (stage III rather than stages I–II [p = 0.05]). MLH1 and MGMT methylation correlated inversely when the tumor was located in the lower third of the stomach (coefficient, –0.48; p = 0.01). DAPK-1 and MLH1 methylation correlated inversely in tumors in the middle-third of the stomach (coefficient, –0.41; p = 0.01).ConclusionGene promoter methylation depends on the gastric tumor location.
With increasing complexity of electronic components and their systems, their cooling solutions become an important issue, and heat sinks are the most widely applied solution in industry. Theoretical, experimental and numerical methods can be used to determine a heat sinks thermal performance. Finite element method is probably the most suitable numerical technique to simulate thermal fields of heat sinks. The advantages of finite element modelling and analysis of heat sinks are discussed. Thermal modelling of heat sink mounted inside air channel was accomplished using finite element analysis software COMSOL. Algorithm for heat sink model building was offered. Finite element mesh generation and problem solution performance was evaluated using created algorithm. Performance evaluation results are presented.Index Terms-Finite element method, heat sink, automated modelling.
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