CONSIDERATIONS ON THE IMPORTANCE OF PROPER HEAT TRANSFER COEFFICIENT MODELING IN AIR COOLED ELECTRONIC SYSTEMS

This paper illustrates, based on a practical example of a hybrid circuit, the influence of proper heat transfer coefficient modelling in air cooled electronic systems on the accuracy of thermal simulations. This circuit contains a transistor heat source and a set of temperature sensors. The measurements of their temperature responses are taken in natural convection and forced air cooling conditions. The experimental data provide the information necessary to estimate the local heat transfer coefficient values in heat source and temperature sensor locations. Moreover, the experiments rendered possible the fitting of parameters of an empirical heat transfer coefficient model for different surface temperature rise values and cooling air velocities, and hence allowed significant improvement of thermal simulation accuracy

Catalytic conversion of methylated aromatics over wood-derived chars – the role of reforming agents and the effect of methyl groups

Toluene steam reforming was performed over three wood-derived chars and compared with a previously-reported pyrolytic conversion study. The heterogeneous mechanism of toluene decomposition was not directly affected by the introduction of steam, but it caused gasification of char and toluene-derived coke, which prolonged the initial high conversion efficiency. Conversely, when oxygen was used as a substitute for steam, a direct ring-opening reaction of toluene was observed, rather than solid carbon combustion. A comparison of benzene, toluene, and p-xylene conversion revealed that the presence of a methyl group on the aromatic ring enhanced its decomposition, regardless of the catalyst’s activity. However, a second methyl group did not further improve the conversion and only served to increase the intensity of secondary recombination reactions

Fifth European Dirofilaria and Angiostrongylus Days (FiEDAD) 2016

Peer reviewe

Relatório de estágio em farmácia comunitária

Relatório de estágio realizado no âmbito do Mestrado Integrado em Ciências Farmacêuticas, apresentado à Faculdade de Farmácia da Universidade de Coimbr

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

The Numerical Approaches to Heat Transfer Problem in Modern Electronic Structures

The main aim of this paper is to present a detailed description of the research related to the modeling of heat conduction in modern electronic structures including special consideration of numerical aspects of analyzed algorithms.The motivation to undertake the research and some most important results of experiments and simulations are also included.Moreover, the numerical appoximation of the problem as well as the methodology and the sample solution of mentioned problem are presented.In the main part, the discretisation techniques, Ordinary Differential Equation algorithms and simulation results for Runge-Kutta and Gear's algorithms are analysed and discussed.Additionally, a new effective approach to modelling of heat transfer in electronic nanostructures is demonstrated

Comparison of two-dimensional dual-phase-lag and Fourier-Kirchhoff model order reduction using Krylov subspace method

https://doi.org/10.26485/0459-6854/2018/68.1/5 Niniejszy artykuł prezentuje porównanie rozkładów temperatury w dwuwymiarowej strukturze nanometrycznej otrzymanych przy pomocy dwóch róznych modeli przepływu ciepła. Pierwszy z nich wyraża klasyczne podejście bazujące na modelu Fouriera-Kirchhoffa, podczas gdy drugi wykorzystuje nowoczesną metodologię nawiązują do równania Dual-Phase-Lag. W obu przypadkach dokonano również redukcji rzędu modeli termicznych. Proces redukcji oparto na metodzie podprzestrzeni Krylova. Wszystkie wyniki zostały ponadto uważnie przeanalizowane i omówione.https://doi.org/10.26485/0459-6854/2018/68.1/5 This paper presents the comparison of the temperature distribution in two-dimensional nanometric structure received using two different heat transfer models. The first one is the classical approach based on Fourier-Kirchhoff model, while the second one uses the modern methodology related to Dual-Phase-Lag equation. In both cases the reduced order models have been also prepared. The reduction process was based on the Krylov subspace method. All results have been carefully analysed and discussed in this paper