196,112 research outputs found
Numerical analysis of the effects of the structure shape and orientation of kelvin cell porous structures during air forced convection
No full textIn recent years, in order to counteract the growth of environmental pollution and the contemporary scarcity of various energy sources, researchers have proposed innovative and efficient solutions for heat transfer applications. Extended surfaces, which can involve the use of fins, open cell metal foams, etc., have been demonstrated to be promising solutions. Open cell metal foams consist of structs intersecting at nodes resulting in stochastic oriented cells. Periodic metal foams have also attracted great interest. These structures are made of a single cell unit periodically replicated. Kelvin cells and Weaire–Phelan ones are two conventional elementary unit cells. In this paper, a numerical model is developed and validated, aiming at analysing the thermal and hydraulic behaviors of modified Kelvin cell-based metal foams during air forced convection. Constant porosity (0.9) and pore density (40 PPI) were adopted. Five different geometrical configurations (one cylindrical and four elliptical) and four orientations (0–15–30–45◦ ) of the struts with respect to the main air flow direction were investigated. The inlet air velocities varied between 0.5 and 4 m s−1 . Interesting results were obtained and discussed in terms of pressure drops, heat transfer coefficients, and pumping power per area density
Energy performance of water strip modules for industrial heating in real operation conditions: Steady-state and CFD analyses
No full textThe objective of this study is the theoretical evaluation of the energy performance of a radiant strips heating system fed with hot water by varying the operating conditions. First, the convective coefficients and the heating power (both convective and radiant parts) of the heating system are evaluated in steady-state conditions by simulating heat exchange similar to real operating conditions (such as the presence of a ventilation system, the opening of doors, windows, or skylights, etc.), in comparison with the nominal data. To carry out this preliminary assessment, different references in the scientific literature are considered with respect to experimental measurements and numerical simulations for similar applications. The steady-state analysis revealed that the increase in the overall yield of the heating strips, compared to the data measured according to the EN 14,037 standard, is in the order of 30%. Afterward, a CFD analysis is reported to dynamically study the effect of the above-mentioned typical situations of real operation of the system in industrial sheds. The CFD analysis confirms that the presence of constant air exchange leads to an improvement of more than 30% in the performance of the water strip system. The main conclusion is that designing the water strip system following the EN 14,037 standard probably will oversize the industrial heating plant
NCAM1, TACR1 and NOS Genes and Temperament: A Study on Suicide Attempters and Controls
No full textSuicide, one of the leading causes of death among young adults, seems to be plausibly modulated by both genetic and personality factors. The aim of this study was to dissect the potential association between genetics and temperament in a sample of 111 suicide attempters and 289 healthy controls. We focused on 4 genes previously investigated in association with suicide on the same sample: the nitric oxide synthase 1 and 3 (NOS1 and NOS3), the neuronal cell adhesion molecule 1 (NCAM1), and the tachykinin receptor 1 (TACR1) genes. In particular, we investigated whether a set of genetic variants in these genes (NOS1 : rs2682826, rs1353939, rs693534; NOS3 : rs2070744, rs1799983, rs891512; NCAM1 : rs2301228, rs1884, rs1245113, rs1369816, rs2196456, rs584427; TACR1 : rs3771810, rs3771825, rs726506, rs1477157) were associated with temperamental traits at the Temperament and Character Inventory (TCI). No strong evidence was found for the association between TCI personality traits and the polymorphisms considered in the 4 genes, with the exception of an association between reward dependence trait and the rs2682826 SNP in NOS1 in the healthy sample. However, this result could be plausibly interpreted as a false-positive finding. In conclusion, our study did not support the thesis of a direct modulation of these genes on temperament; however, further studies on larger samples are clearly required in order to confirm our preliminary findings and to exclude any possible minor influence. Copyright (C) 2011 S. Karger AG, Base
Thermal storage based on phase change materials (PCMs) for refrigerated transport and distribution applications along the cold chain: A review
No full textFoodstuff has to be transported from where it is produced or packaged to the market. It is important to control the temperature and humidity of the delivered food to minimize the waste and ensure customer satisfaction. At the same time, unfortunately, the transport sector is among the polluting sectors. Therefore, innovative solutions have been proposed such as the adoption of Latent Thermal Energy Storage (LTES) systems based on Phase Change Materials (PCMs) to control the food temperature. Such systems minimize the fuel consumption and thereby reduce the emission. LTES systems rely on the phase change process to absorb and store heat in a more sustainable way while ensuring a nearly constant temperature for the foodstuff while being transported. Hence, we first present a general overview of the application of PCMs at low temperatures. Then, the literature on the adoption of PCMs in the refrigerated transport sector is critically surveyed. Different proposals offered in the literature..
3D numerical simulation of a novel ventilated roof: thermal performance analysis and fluid flow behavior
No full textThis paper presents a numerical simulation of a ventilated roof based on a novel plastic support especially designed to reduce the solar heat gains by improving the airflow distribution as compared to a traditional one. In order to evaluate the benefits of the new configuration, a 3 D numerical model was developed allowing for a deep understanding of the airflow distribution inside the ventilated roof channels. The simulations were performed by varying the solar irradiance from 600 to 1000 W m−2 assuming buoyancy-driven airflow. The investigation was conducted by comparing the new proposed ventilated roof assembly to the traditional layouts. In particular, two roof types were considered as benchmarks: an insulated roof and a non-insulated one. When compared to the traditional ones, the results revealed that the innovative ventilated roof led to a great reduction (up to 70%) of the total amount of solar heat gains for all the simulated scenarios
Approximate and CFD energy performance analyses of industrial heating by water strip modules – Part 1
No full textPreliminary suicide trends during the COVID-19 pandemic in Milan, Italy
No full textEurope was the second most affected continent by the 2019 coronavirus disease (COVID-19) pandemic, with Italy paying very high death tolls, especially in Lombardy, a region in Northern Italy. The pandemic profoundly impacted mental health and the world's rates of suicide since its outbreak. COVID-19-related suicide rates nonetheless followed a non-linear trend over the pandemic, decreasing after the COVID-19 outbreak, then raising during an extended follow-up period. Thus, we aimed to further assess the suicide rates in Lombardy. We carried out a retrospective analysis of all the autopsies performed in the year 2020 and within the first four months of the year 2021 through the database of the Institute of Forensic Medicine in Milan. In the year 2020, the recorded suicides decreased in comparison to 2016-2019 (21.19-22.97% of the autopsies), being 98 (18.08% out of 542 autopsies), while, in the first 4 months of the year 2021, 35 suicides were documented (185 autopsies, overall). Since the region of Lombardy was severely affected by COVID-19 since the early months of the year 2020, the extended retrospective follow-up allowed for firmer conclusions and insights about the need to extend the follow-up of COVID-19 pandemic beyond the first months after the outbreak, worldwide. This is with special emphasis towards the need to allocate the proper funds for mental health prevention for the general population as well as the most vulnerable ones, such as people with severe mental illness and caregivers, frontline health workers, and others bereaved by COVID-19
Water Pool boiling on Aluminum Metal Foams
No full textWith current growth in electronic systems, their physical sizes decrease, and the spacing between components decreases, both the total amount of heat generated and the power density increase significantly. There is a general agreement in the scientific community that current air-cooling technologies are asymptotically approaching their intrinsic limits. Pool boiling is widely used in many different engineering systems, but most of these applications have a common limitation: the maximum heat flux that can be rejected by the cooling systems under safe, reliable, and efficient operation. In this paper experimental data pertinent to deionized water pool boiling across 10 mm thick aluminum foams are presented. Three foam samples with different pore densities, 5, 10, and 40 PPI, yet with an identical mean porosity of 0.92 are tested. Compared to a heated flat plate, the foams offer higher heat transfer area albeit at induced bubble escaping resistance. The tradeoff between these two effects is investigated. Through the use of high speed video camera recording, bubble generation, trajectory and growth rate were analyzed and critically discussed
Genetic modulation of borderline personality disorder: systematic review and meta-analysis.
No full textBorderline personality disorder (BPD) is a highly prevalent psychiatric disorder with high morbidity and mortality. Early theories ascribed an environmental etiology of BPD, but growing evidence supports a genetic vulnerability as well. The primary aim of this study was to systematically review genetic association studies focused on BPD. PubMed, ISI Web of Knowledge and PsycINFO databases were searched for studies published until December 2012. Meta-analyses were also performed when three or more studies reported genetic data on the same polymorphism. Data were analyzed with Cochrane Collaboration Review Manager Software (RevMan, version 5.0). Quality and publication bias were assessed. The systematic review of association studies examining genetic polymorphisms and BPD produced conflicting results. Meta-analyses were performed for three serotonergic polymorphisms: two common polymorphisms of the serotonin transporter gene (SLC6A4), the promoter insertion/deletion (5-HTTLPR) and the intron 2 VNTR (STin2 VNTR), and the rs1800532 (A218C) polymorphism of the tryptophan hydroxylase 1 gene (TPH1), all showing no association. No direct role of genetic polymorphisms was found in BPD. However, a few studies only are present in literature to draw definite conclusions. Further studies focusing on gene × gene and gene × environment interactions are needed to more deeply dissect the genetic role in the modulation of BPD
Does COVID-19 Impact Less on Post-stroke Aphasia? This Is Not the Case
No full textBackground: The coronavirus disease 2019 (COVID-19) pandemic has greatly affected people’s mental health resulting in severe psychological consequences. One of the leading causes of long-term disability worldwide is aphasia. The language changes experienced by a person with aphasia (PWA) often have a sudden and long-lasting negative impact on social interaction, quality of life, and emotional wellbeing. The main aim of this study was to investigate the impact of COVID-19 on the different psychosocial dimensions which affect PWA. Methods: This retrospective study included 73 PWA and 81 elderly matched controls. All patients were in the chronic phase. They were all discharged from rehabilitation services, which left them with different degrees of language deficits (i.e., severe vs. mild vs. moderate). All participants were administered the hospital anxiety and depression scale (HADS) through an online survey. PWA also took part in the stroke and aphasia quality of life scale questionnaire (SAQOL-39). Results: Although the comparison between two different time points [one month before (T0) and one month after the lockdown (T1)] led to a significant increase in depression and anxiety symptoms in both groups (PWA vs. control), lower rates of depression and anxiety were found in PWA compared to the healthy group. Significant deterioration was also present in PWA in the communication and psychosocial scales of the SAQOL-39 test, which correlated with the observed changes in the psychological domains. Interestingly, the results were not significantly influenced by the degree of aphasia severity. Similarly, in both groups, none of the demographic variables (gender, age, and educational level) significantly affected the scores in the different subscales. Conclusions: This evidence which, at first glance, seems to suggest that PWA have been partially spared from the impact of COVID-19, actually masks a dramatic situation that has always characterized this population. Indeed, given that PWA already live in a state of social isolation and emotional instability, these conditions might have, paradoxically, limited the effects of the coronavirus. However, as our results showed a deterioration in the emotional state and communication skills of our patients, possible solutions are discussed in order to prevent further decline of their cognitive abilities
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