Statistical properties of microcracking in polyurethane foams under tensile test, influence of temperature and density

We report tensile failure experiments on polyurethane (PU) foams. Experiments have been performed by imposing a constant strain rate. We work on heterogeneous materials for whom the failure does not occur suddenly and can develop as a multistep process through a succession of microcracks that end at pores. The acoustic energy and the waiting times between acoustic events follow power-law distributions. This remains true while the foam density is varied. However, experiments at low temperatures (PU foams more brittle) have not yielded power-laws for the waiting times. The cumulative acoustic energy has no power law divergence at the proximity of the failure point which is qualitatively in agreement with other experiments done at imposed strain. We notice a plateau in cumulative acoustic energy that seems to occur when a single crack starts to propagate

Machine learning for estimation of building energy consumption and performance:a review

Ever growing population and progressive municipal business demands for constructing new buildings are known as the foremost contributor to greenhouse gasses. Therefore, improvement of energy eciency of the building sector has become an essential target to reduce the amount of gas emission as well as fossil fuel consumption. One most eective approach to reducing CO2 emission and energy consumption with regards to new buildings is to consider energy eciency at a very early design stage. On the other hand, ecient energy management and smart refurbishments can enhance energy performance of the existing stock. All these solutions entail accurate energy prediction for optimal decision making. In recent years, articial intelligence (AI) in general and machine learning (ML) techniques in specic terms have been proposed for forecasting of building energy consumption and performance. This paperprovides a substantial review on the four main ML approaches including articial neural network, support vector machine, Gaussian-based regressions and clustering, which have commonly been applied in forecasting and improving building energy performance

Diastolic dysfunction in diabetes and the metabolic syndrome: promising potential for diagnosis and prognosis

Cardiac disease in diabetes mellitus and in the metabolic syndrome consists of both vascular and myocardial abnormalities. The latter are characterised predominantly by diastolic dysfunction, which has been difficult to evaluate in spite of its prevalence. While traditional Doppler echocardiographic parameters enable only semiquantitative assessment of diastolic function and cannot reliably distinguish perturbations in loading conditions from altered diastolic functions, new technologies enable detailed quantification of global and regional diastolic function. The most readily available technique for the quantification of subclinical diastolic dysfunction is tissue Doppler imaging, which has been integrated into routine contemporary clinical practice, whereas cine magnetic resonance imaging (CMR) remains a promising complementary research tool for investigating the molecular mechanisms of the disease. Diastolic function is reported to vary linearly with age in normal persons, decreasing by 0.16 cm/s each year. Diastolic function in diabetes and the metabolic syndrome is determined by cardiovascular risk factors that alter myocardial stiffness and myocardial energy availability/bioenergetics. The latter is corroborated by the improvement in diastolic function with improvement in metabolic control of diabetes by specific medical therapy or lifestyle modification. Accordingly, diastolic dysfunction reflects the structural and metabolic milieu in the myocardium, and may allow targeted therapeutic interventions to modulate cardiac metabolism to prevent heart failure in insulin resistance and diabetes

Design of a fuzzy system for living space thermal-comfort regulation

The present paper describes the design of a living space comfort regulator using fuzzy logic. Comfort is a fuzzy concept, different for different people and depending on the work done in the space. The paper describes the structure of the system, the available measurements and the available actuators, the measurement fuzzification process and the defuzzification method. Particular attention is paid to the proper selection of the rules in the knowledge base and the design of the inference engine. Finally the system is tested, and shows satisfactory performance. General design guidelines are given, including the case of spaces having different actuators.Fuzzy logic control Fuzzy thermal comfort Expert system Thermal comfort regulation Fuzzy system

Heat and mass transfer through large openings by natural convection

Convective heat and mass transfer through large openings play an important role in the thermal behaviour of buildings. These phenomena become even more determinant in the case of naturally ventilated buildings. This paper reviews the models describing the involved phenomena due to gravitational and boundary layer pumping flows proposed up to 1992. A sensitivity analysis is also presented, aimed at a comparison of these models and a determination of the points requiring further research. © 1995

Relative and population attributable risk of traffic injuries in relation to blood-alcohol levels in a Mediterranean country

Blood samples were taken from, and interviews were conducted with, 76 persons injured in motor vehicle crashes, and from 126 controls with a home and leisure injury. The analysis was undertaken by modelling the data through conditional logistic regression, controlling for gender- and age-marched variables and other potentially confounding variables, including education and visual acuity. Detectable alcohol levels were associated with a 4.9 relative risk (95% confidence intervals 1.4 to 16.8). The population attributable fraction was about 10% with wide confidence intervals. There was no evidence for a safe threshold in these data. The increased injury risk associated with detectable blood-alcohol levels was disproportionally, albeit non-significantly, elevated among occasional drinkers in comparison to regular drinkers. We conclude that alcohol intake is an important cause of road traffic injuries even in the context of the Mediterranean countries where alcohol is taken in moderation and mainly in the form of wine during meals