Decrease of the maximum speed in highway tunnels as a measure to foster energy savings and sustainability

The high energy consumption of the lighting installations in highway tunnels has become a hot topic in the last few years due to the high figures in terms of money, consumed energy, use of raw materials, emissions of greenhouse gases due to the remarkable number of manufactured elements, and maintenance, among others. In spite of the different strategies proposed up to date and their savings, the potential benefits of decreasing the maximum speed allowed in tunnels have not been considered in depth as a complementary measure yet. In this work, the impact of such a decrease in terms of energy consumption, number projectors, carbon dioxide (CO2) emissions, and yearly costs in energy is analyzed and discussed. The results strongly suggest the convenience of introducing maximum speed reduction in traffic regulations which, in addition, could create positive synergies with traffic safety

A multivariate generalized independent factor GARCH model with an application to financial stock returns

We propose a new multivariate factor GARCH model, the GICA-GARCH model , where the data are assumed to be generated by a set of independent components (ICs). This model applies independent component analysis (ICA) to search the conditionally heteroskedastic latent factors. We will use two ICA approaches to estimate the ICs. The first one estimates the components maximizing their non-gaussianity, and the second one exploits the temporal structure of the data. After estimating the ICs, we fit an univariate GARCH model to the volatility of each IC. Thus, the GICA-GARCH reduces the complexity to estimate a multivariate GARCH model by transforming it into a small number of univariate volatility models. We report some simulation experiments to show the ability of ICA to discover leading factors in a multivariate vector of financial data. An empirical application to the Madrid stock market will be presented, where we compare the forecasting accuracy of the GICA-GARCH model versus the orthogonal GARCH one

Considerations on the effects of automotive lighting to enhance alert and avoid sleepiness in night time drivers via melatonin inhibition

The effects of light on circadian rhythms have been known for a long time. It is well known that shift workers, transoceanic travellers and other people being exposed to light during their sleep hours have remarkable disorders in their biological clocks that can last just some days with few important effects or become really serious with higher incidence of serious diseases. One of the reasons for circadian clock to be altered is the melatonin inhibition, due to the exposure to intense and/or bluer lights during sleep hours. The inhibition of the secretion of this neurohormone has been proven to be an effective measure to enhance alert and avoid sleepiness. However, although this sleepiness avoidance is widely used in indoor illumination to achieve better productivities or higher concentration in mental tasks, nothing has been done in order to ensure that night time drivers will keep awake during long journeys via melatonin inhibition. In this sense, the lighting of the own vehicle could be the most reasonable candidate to avoid sleepiness on this collective with the consequent impact on safety. This work uses the theoretical models of dependence between light intensity and wavelength and melatonin inhibition to analyze the potential influence of car headlamps on sleepiness in people driving during long periods at night-time. The results of this research show that cars equipped with headlamps using xenon and halogen light sources, which are the most common with a still wide advantage on LEDs cause no melatonin inhibition on people driving during long periods at night and thus, the current automotive lighting technology cannot avoid distraction and sleepiness in drivers with this strategy. However, a new lighting pattern that theoretically would cause melatonin inhibition and hence, an enhanced road safety, is proposed. We conclude that the incorporation of headlighting systems providing this pattern would be extremely positive for road safety and one important step for the automotive industr

An Approach for Lighting Calculations in Indoor Mirrored Facilities Based on Virtual Twin-Spaces

The presence of walls with different reflectance in indoor facilities is a problem when designing their lighting installations. This problem becomes more serious when one or more walls are mirrors, a common situation in medical, sport, educative and many other indoor facilities. Even if some programs can work with different approaches, the results are far from exact and, in many cases, designers ignore the mirrors and work by eye, with results that are frequently excessive in terms of illuminance on the working planes, glare and energy consumption and use of materials. These deviations from the intended results are due to the direct or indirect estimation of reflectance remarkably lower than 1 in the mirrored walls. In this framework of uncertainty, this work is presented with the objective of developing an intuitive theoretical model based on the consideration of virtual twin-spaces behind the mirrors. This proposal is not just an approach, but a useful tool providing the input for any kind of calculation ranging from the lumen method, used in quick pre-dimensioning, to the most complete calculations with computational methods. In addition, apart from calculating the number of luminaires and photometric parameters, the use of virtual twin-rooms also takes into account the extended field of vision of the users, including objects behind, and virtual luminaries. This advantage has no precedent in the literature up to date

CFD study of carotid artery haemodynamic flows with experimental validation

The behavior of the veins and arteries under some potentially life-threatening situations has been the object of study for a long time. However, these studies have been mostly carried out experimentally, usually conditioned by the situation and procedure of the analysis itself. That is the reason why during the past years, with the development of computational fluid dynamics, there has been a growing interest in creating models to simulate these situations, in order to imitate blood behavior in a generic way. Therefore, during this study, a CFD analysis of the internal flow through the carotid artery bifurcation has been carried out. In first place, starting from a three-dimensional geometry of the artery, a meshing process has been realized using the open-access software Salome, including the optimization of the mesh itself. Later, multiple simulations have been carried out with different characteristics in order to end up obtaining a model as close with the reality as possible, and numeric results have been obtained using the open-access software OpenFOAM. Finally, these results have been compared and validated with the results of previous numerical and experimental projects, and comparisons between different viscosity models have been carried out based on the results obtained

Scaled hillsides to decrease the energy consumption of lighting installations in road tunnels

The reduction of energy demands of the lighting installations in road tunnels, has become a matter of active research in the last years. Among the different strategies, the decrease of reflectance in the surroundings of portal gate, has been pursued by means of forestation or installation of elements with lower reflectance than concrete. However, these strategies are difficult to carry out due to remarkable problems like initial implementation, maintenance, shape of the mountain and other properties of the terrain. Furthermore, they consider only the decrease in the reflectance without controlling the directions where the light is reflected. This work proposes the introduction in the hillside around the portal of discrete surfaces with given orientation to deviate the reflected light from the visual field of drivers. The target is to ease the visual adaptation, making the visual transition smoother, and decrease the glare and luminance in the zone of the road that determines the lighting requirements inside the tunnel. The result is a scaled-like zone around the portal whose parameters are calculated, analyzed, and presented in this work

A multivariate generalized independent factor GARCH model with an application to financial stock returns

We propose a new multivariate factor GARCH model, the GICA-GARCH model , where the data are assumed to be generated by a set of independent components (ICs). This model applies independent component analysis (ICA) to search the conditionally heteroskedastic latent factors. We will use two ICA approaches to estimate the ICs. The first one estimates the components maximizing their non-gaussianity, and the second one exploits the temporal structure of the data. After estimating the ICs, we fit an univariate GARCH model to the volatility of each IC. Thus, the GICA-GARCH reduces the complexity to estimate a multivariate GARCH model by transforming it into a small number of univariate volatility models. We report some simulation experiments to show the ability of ICA to discover leading factors in a multivariate vector of financial data. An empirical application to the Madrid stock market will be presented, where we compare the forecasting accuracy of the GICA-GARCH model versus the orthogonal GARCH one.ICA, Multivariate GARCH, Factor models, Forecasting volatility

Exploring ICA for time series decomposition

In this paper, we apply independent component analysis (ICA) for prediction and signal extraction in multivariate time series data. We compare the performance of three different ICA procedures, JADE, SOBI, and FOTBI that estimate the components exploiting either the non-Gaussianity, or the temporal structure of the data, or combining both, non-Gaussianity as well as temporal dependence. Some Monte Carlo simulation experiments are carried out to investigate the performance of these algorithms in order to extract components such as trend, cycle, and seasonal components. Moreover, we empirically test the performance of those three ICA procedures on capturing the dynamic relationships among the industrial production index (IPI) time series of four European countries. We also compare the accuracy of the IPI time series forecasts using a few JADE, SOBI, and FOTBI components, at different time horizons. According to the results, FOTBI seems to be a good starting point for automatic time series signal extraction procedures, and it also provides quite accurate forecasts for the IPIs.ICA, Signal extraction, Multivariate time series, Forecasting

El papel de los recursos naturales en los conflictos territoriales de Sinkiang y Tíbet en la República Popular China

More than 1,437 million people inhabit China. More than 91% are ethnic Han, leaving the rest divided into more than fifty groups officially recognized as minority nationalities. The history of China has seen clashes between some minority groups and the State, even of a secessionist nature. Some of them reach the present day, as in Xinjiang Uyghur Autonomous Region and Tibet. This article examines the weight that natural resources and other geopolitical benefits for the Chinese State can have in both territories. The working hypothesis is that these resources and benefits are essential for China's economic and geopolitical interests.En China viven más de 1.437 millones de personas. Más del 91% son de etnia Han, quedando el resto dividido en más de cincuenta grupos reconocidos oficialmente como nacionalidades minoritarias. La historia de China ha visto enfrentamientos entre algunos grupos minoritarios y el Estado, incluso de carácter secesionista. Algunos de ellos llegan hasta nuestros días, como en la Región Autónoma Uigur de Sinkiang y en Tíbet. Este artículo presenta el peso que los recursos naturales y otros beneficios geopolíticos para el Estado chino pueden tener en ambos territorios. La hipótesis de trabajo es que estos recursos y beneficios son esenciales para los intereses económicos y geopolíticos de China

Daylighting of road tunnels through external ground-based light-pipes and complex reflective geometry

The transfer of solar light to the interior of tunnels to complement electrical lighting during daytime, contributes to save energy and decrease the number of installed projectors. The solutions traditionally implemented, based on light-pipes hanging from the vault, seemed reasonable because the leakages of light-pipes can emit luminous flux like projectors, but had the disadvantage of needing higher clearance gauges with the consequent costs in drilling, building materials, works and maintenance. Furthermore, these hanging light-pipes cannot be installed in working tunnels if they were not foreseen in the initial project. In this article, a new concept of light injection and distribution in tunnels is proposed. It consists of the coupling of three main elements: collectors, light-pipes, and one reflecting vault whose design is optimized to ensure the photometric requirements on the pavement. The proposed system can collect more than 1.5 Mlm of solar flux with not excessively large collectors installed on the ground of the road shoulder, and project them to the vault that finally distributes the light towards the pavement. With this flux, average illuminances of 3478 lx and uniformities of 0.73 can be achieved, which means pavement luminance around 350–400 cd/m2, in good agreement with the requirements during daytime. The savings can be higher than 40 %. Besides these savings, this system can be easily implemented in existing tunnels. The proposal and some estimations are discussed