Parametric analysis of energy harvesting pavements operated by air convection

In this paper, an energy harvesting pavement prototype using air as the operating fluid is described and analysed. The prototype harvests the thermal energy available in the pavement through pipes embedded in its structure, where air flows thanks to natural convection. The air is able to exit the system through an updraft chimney. A parametric analysis of the controllable parameters of interest is performed in this work in order to evaluate the variation in the performance of the energy harvesting prototype in different experimental setups. This study shows that there exists a maximum value for the air speed in each configuration and that the energy harvesting efficiency depends on the height and the diameter of the chimney. Moreover, there is a minimum value of the chimney diameter that does not allow air movement and makes the whole system behave as if no pipes were embedded in the pavement structure

Influence of urban form on the performance of road pavement solar collector system: symmetrical and asymmetrical heights

Recent works have highlighted the importance of mitigating the urban heat island effect using innovative technologies. Several studies have emphasised the capabilities of the road pavement solar collector system to dissipate high temperature from the pavement/road surfaces not only to expand its lifecycle but also to reduce the Urban Heat Island effect. This study builds on previous research combining an urban configuration and a road pavement solar collector system in Computational Fluid Dynamics in order to understand the complicated connection of the urban environment and the road pavement. This study investigates the impact of the urban form on the performance of the road pavement solar collector focusing on comparing symmetrical and asymmetrical height of the urban street canyon. A tridimensional de-coupled simulation approach was used to simulate a macro domain (urban environment) and micro domain, which consists of road pavement solar collector pipes. ANSYS Fluent 15.0 was employed with the solar load model, Discrete Ordinate radiation model and Reynold Averaged Navier Stokes with standard k-epsilon equation. The simulation was carried out based on the summer month of June in Milan urban centre, Italy. Results showed a significant variation in the temperature results of road surface in comparing the three configurations. It was also found that there was a significant reduction in the road pavement solar collector system performance when taller building row was behind the first approaching building row. The method presented in this research could be useful for studying the system integration in various urban forms

Construction and configuration of convection-powered asphalt solar collectors for the reduction of urban temperatures

In this paper, an analysis of a convection-powered asphalt solar collector prototype is approached by the means of experimental trials and computational fluid dynamics (CFD) simulations in order to evaluate how to optimise its design for the reduction of high urban pavement temperatures. Since the energy harvesting setup consists of a series of pipes buried in the pavement, their arrangement is here studied and experimentally compared to a possible construction technique consisting of concrete corrugations that aim at replacing the pipes. CFD simulations are employed to optimise the air collection chamber which is placed immediately before the heated air leaves the asphalt solar collector prototype. The data gathered is analysed in terms of energy harvested and exergy. The results obtained show that for an overall optimal performance, pipes should be installed in a single row under the pavement wearing course. This allowed a surface temperature reduction of up to 5.5 °C in the pavement prototype studied and the highest absorbed energy and exergy measured. In addition, the CFD simulations showed that care has to be put in finding the optimal shape and size for the air collection chamber, as they significantly influence the behaviour of the system

A study of the impact of building geometry on the thermal performance of road pavement solar collectors

Studies on RPSC (road pavement solar collectors) have shown the potential of reducing the UHI (urban heat island) effects by dissipating the heat from the pavement for energy harness. Several works have shown that the generated heat could be utilised for sustainable urban energy system. However, none of the previous literatures have assessed the effect of building geometry on the performance of the RPSC. This study investigates the thermal performance of an urban-integrated RPSC system by using CFD (computational fluid dynamic) simulation of integrated RPSC system with a standard urban canyon domain and an empty domain. Based on 21st June at 13:00, it was found that the RPSC system in urban canyon domain was on average 36.08% more effective in thermal collection and provided on average 27.11% more surface temperature reduction as compared to the RSPC application in rural/flat domain. The RPSC performance based on the effect from daily solar intensity was initiated with results demonstrated the efficiency of the RPSC in an urban setting was 7.14%–63.26% more than the rural/flat setting. Simulations of various wind speeds in summer day(s) and the impact of seasonal changes to the RPSC system were also conducted to investigate the deficiency factors to the system

Combining MRI and clinical data to detect high relapse risk after the first episode of psychosis

Detecting patients at high relapse risk after the first episode of psychosis (HRR-FEP) could help the clinician adjust the preventive treatment. To develop a tool to detect patients at HRR using their baseline clinical and structural MRI, we followed 227 patients with FEP for 18–24 months and applied MRIPredict. We previously optimized the MRI-based machine-learning parameters (combining unmodulated and modulated gray and white matter and using voxel-based ensemble) in two independent datasets. Patients estimated to be at HRR-FEP showed a substantially increased risk of relapse (hazard ratio = 4.58, P < 0.05). Accuracy was poorer when we only used clinical or MRI data. We thus show the potential of combining clinical and MRI data to detect which individuals are more likely to relapse, who may benefit from increased frequency of visits, and which are unlikely, who may be currently receiving unnecessary prophylactic treatments. We also provide an updated version of the MRIPredict software

Development and Cross-Validation of the UPSA Short Form for the Performance-Based Functional Assessment of Patients With Mild Cognitive Impairment and Alzheimer Disease

Functional capacity includes basic and complex behaviors necessary to independently live in the community. It has been found that patients with cognitive impairment have daily living functional skills altered at very early stages of illness. 1) To develop and validate a brief scale derived from the University of California, San Diego, performance-based skills assessment (UPSA); 2) to cross-validate this new UPSA short form with an independent healthy elderly sample. Fifty-one healthy elderly subjects, 26 mild cognitive impairment (MCI) subjects defined per Petersen's criteria, and 22 probable Alzheimer Disease (AD) subjects according to National Institute of Neurological and Communicative Disorders and Stroke–AD and Related Disorders Association criteria were included. For cross-validation purpose, a comparison group of 108 older healthy subjects with Mini-Mental scores of 25 or greater was also recruited. A modified four-functional domain version of the UPSA was administered. Communication and comprehension/planning domains accounted for almost 90% of the variance (R2 = 0.89) and in all models entered first and second, respectively. An UPSA short form using these two domains was significantly correlated with the full UPSA scale in all the groups examined: 0.86 for healthy controls; 0.87 for MCI; and 0.88 for AD. Acceptable sensitivity and specificity values for the UPSA short form were found in receiver operating characteristic (ROC) analysis. A correlation of 0.80 was found between the short and the full UPSA scales in the cross-validation sample. The UPSA short form is a rapid, reliable, and efficient measure of functional capacity that is able to detect performance impairment in an ecologically valid setting in much less time compared with the extended form of the scale. Furthermore, it demonstrated adequate discriminative properties among healthy subjects, MCI patients, and AD patients

Field evaluation of the effects of air convection in energy harvesting asphalt pavements

In this article, the performance of a convection-powered air flow through an asphalt prototype pavement is investigated in a field test. An asphalt prototype pavement with pipes buried in its aggregate layer was connected to a constant temperature heat source and installed at the University of Nottingham, UK. In the experimental configuration chosen, air at 15 °C was free to flow through the prototype pavement by natural convection and exit through a vertical chimney. The natural convection flow was meant to cool down or heat up the pavement based on the temperature gradient between the pavement surface and the air in the pipes. The experimental setup included a weather station and aimed to analyse the effect of the heat fluxes from and to the air in the pipes on the development of the surface temperature. The experimental results produced a large dataset, which was analysed based on physical and statistical principles to provide guidance for future studies in the field. The system designed was able to provide pavement heating and cooling effectively in a real life environment. The maximum extent of the heating and cooling effects was quantified as ±5 °C

Validation of a European Spanish-version of the University of California performance Skills Assessment (Sp-UPSA) in patients with schizophrenia and bipolar disorder

To validate the Spanish version of the University of California Performance Skills Assessment (UPSA) in patients with severe mental disorders. Naturalistic, 6month follow-up, multicentre, validation study. 139 patients with schizophrenia, 57 bipolar patients and 31 controls were evaluated using the following scales: Spanish UPSA (Sp-UPSA), Clinical Global Impression, Severity (CGI-S), Global Assessment of Functioning (GAF), and Personal and Social Performance (PSP). Reliability: Internal consistency (Cronbach's alpha) was 0.81 in schizophrenia and 0.58 in bipolar patients. Test–retest was 0.74 and 0.65 (p<0.0001) respectively. Construct validity: Pearson correlation coefficients between Sp-UPSA and PSP total scores were 0.42 (p<0.0001) for schizophrenia and 0.44 (p=0.001) for bipolar patients. For Sp-UPSA and GAF scores correlation coefficients were 0.43 and 0.52 (p<0.0001) respectively. Discriminant validity: The Sp-UPSA discriminated between patients and controls. In schizophrenia patients it also discriminated among different levels of illness severity according to CGI-S scores. In control versus patients with schizophrenia contrasts, the area under the curve was 0.89 and a cut-off point of 85 provided a sensitivity of 82.7% and a specificity of 77.4%. In bipolar patients, the area under the curve was 0.85 and a cut-off point of 90 provided a sensitivity of 82.5% and a specificity of 64.5%. The Spanish UPSA is a reliable and valid instrument for assessing functional capacity in severe mentally ill patients. It seems to be appropriate for use in clinical trials and in everyday clinical practice as a means of monitoring functional outcomes