Spanish Demand for Food Away From Home: A Panel Data Approach

In this paper, the Spanish demand for food away from home is analysed. A panel data set is built and appropriate techniques for estimating limited dependent variable models have been applied. Results indicate that where there are zero expenditures, these are largely due to infrequency of purchase rather than to abstention or to economic reasons. Furthermore, important differences appear among households. On the one hand, those households whose head is a highly-educated person, male, young and living on a salary in a large town are more likely to purchase food away from home. On the other hand, increases in income only provokes more than proportional increases in expenditure for those households headed by an unschooled person, a female or a person older than 55 and also for those households with more than half of its members older than 60 years.Demand for food away from home, household production theory, panel data., Consumer/Household Economics, C23, C24, D12,

Finite Element Modeling of Rubber Bushing for Crash Simulation - Experimental Tests and Validation

Until recently, the general level of detail in full car crash models has not allowed a physical modeling of rubber bushings with solid elements. This is partly because of the difficulty in modeling the complex characteristic of rubber, but also due to limited understanding of the mechanical properties of rubber materials. The main focus of this Master’s thesis project is to develop a new and improved finite element modeling of rubber bushings for crash simulation, including the model of the bolt joint, which keep the rubber bushing linked to the body structure of the car. The final FE-model has to be able to mimic the real mechanical behavior of the rubber bushing and work effectively in the full-vehicle crash simulation. To achieve this, the program for non-linear dynamic analysis of structures in three dimensions LS-DYNA was used. In order to validate the final FE-model of the rubber bushing system testing activities and comparisons between the full-vehicle crash simulation with the new and improved FE-model of rubber bushing and the traditional one that often is used in the simulations were made. The experimental activities were carried out in the tower test of the Safety Centre of Volvo Car Corporation. In the first part of the thesis, comparisons between the finite element analysis and analytical solution of a simple cylindrical model of rubber exposed to shock loading as well as an estimation of the shear modulus G using the strain energy function of the Yeoh model and an energy balance has been done. The results from the FE-simulation corresponded quite well with the ones from the analytical solution when the Yeoh model is used as the hyperelastic rubber material to model the properties of the rubber. Regarding the FE-model of the rubber bushing system, the rubber part of the bushing was modeled in a rough way. This is because holes, fillets and other design features within the geometry of the rubber bushing rapidly increase the number of elements needed and, as a result, the computational cost of the analysis and the stability of the model are affected. Therefore, the smaller parts of rubber at the surface of the plastic outer sleeve, aluminum inner sleeve and at the corners while meshing the rubber bushing were not taken into account. The rubber bushing and the screw joint were modeled using 8-node solid elements, 4-node and 3-node shell elements and, 2-node beam elements. The 8-node solid elements were used for the rubber, the aluminum inner sleeve and the bolt head, the 4-node and 3-node shell elements were used for the plastic outer sleeve, the washer, the big nut and the cylindrical casing of the bolt, and the 2-node beam elements were used for the thread and the grip of the bolt. The Yeoh model was used to describe the hyperelastic behaviour of the rubber and for the rest of the model, the evaluated material models were mostly characterized by using elastic piecewise linear plasticity with a specific curve stress/strain and a yield strength. The contacts between metal and metal surfaces and between the rubber and the plastic outer sleeve were solved by using the simple global contact and the LS-DYNA option TIED_NODES_TO_SURFACE_OFFSET, respectively. The tightening of the bolt joint was taken into consideration in order to properly describe the friction and contacts between the different parts of the complete rubber bushing system from the beginning of the simulation. The rubber itself turned out to be just a small part of the complete rubber bushing system, so it was not necessary to use a complex material model to predict the physical response of the rubber. A simple and purely hyperelastic rubber material model where no damping exists was used instead. The Yeoh model worked out to be a stable model at high strain rate and therefore was used with theses material parameters: C10 = 0,55, C20 = 0,05, C30 = 0,95. The developed FE-model of rubber bushing system seems to model the nonlinearities in the system as large displacement effects and large deformations, material nonlinearity, and boundary nonlinearities. This is confirmed by the preload in the bolt joint, the contacts, the friction between the different surfaces and the bending and pulling out behaviour of the system working properly at the beginning and during the simulation. In order to validate the final FE-model of the rubber bushing system it was exposed to different loading cases in the FE-simulations and full-scale tests. The FE-simulations were tested under the same conditions as in the experimental tests in order to have a reference for comparisons. The full-scale impacts and computed deformations agreed qualitatively but they differed in magnitude. The deformations of the rubber bushing system, due to the bending moment, axial force and pulling out between sleeves appear to be similar to what happens in reality. The reason for the inaccuracies may be caused by several approximations in the FEmodel and others source of error while carrying out the different experimental test. An US-NCAP analysis was also performed in LS-DYNA in order to be sure that the final FE-model of the rubber bushing system works properly in the full-vehicle crash simulation. The simulation provided satisfactory results in the full-frontal impact of the car showing a significant improvement in the behavior of the rubber bushing system in comparison with the full-vehicle crash simulation of the traditional FE-model of rubber bushing that is often used in the car. Finally, the final FE-model of rubber bushing system can be considered reliable and can be used with a high rate of confidence in the full-vehicle crash simulation, since the computational time can be reduced by up to 4 % approximately and when used in the full vehicle crash simulation, this model is more physical and detailed than the traditional one and can better resemble the mechanical behaviour of the real rubber bushing system

Analytical Expressions for Radiative Opacities of Low Z Plasmas

In this work we obtain analytical expressions for the radiative opacity of several low Z plasmas (He, Li, Be, and B) in a wide range of temperatures and densities. These formulas are obtained by fitting the proposed expression to mean opacities data calculated by using the code ABAKO/ RAPCAL. This code computes the radiative properties of plasmas, both in LTE and NLTE conditions, under the detailed-level-accounting approach. It has been successfully validated in the range of interest in previous works

Impedance and Scattering Variance Ratios of Complicated Wave Scattering Systems in the Low Loss Regime

Random matrix theory (RMT) successfully predicts universal statistical properties of complicated wave scattering systems in the semiclassical limit, while the random coupling model offers a complete statistical model with a simple additive formula in terms of impedance to combine the predictions of RMT and nonuniversal system-specific features. The statistics of measured wave properties generally have nonuniversal features. However, ratios of the variances of elements of the impedance matrix are predicted to be independent of such nonuniversal features and thus should be universal functions of the overall system loss. In contrast with impedance variance ratios, scattering variance ratios depends on nonuniversal features unless the system is in the high loss regime. In this paper, we present numerical tests of the predicted universal impedance variance ratios and show that an insufficient sample size can lead to apparent deviation from the theory, particularly in the low loss regime. Experimental tests are carried out in three two-port microwave cavities with varied loss parameters, including a novel experimental system with a superconducting microwave billiard, to test the variance-ratio predictions in the low loss time-reversal-invariant regime. It is found that the experimental results agree with the theoretical predictions to the extent permitted by the finite sample size.Comment: 8 pages, 5 figure

How new technologies can promote an active and healthy city. Digital platform to identify areas of informal sport practise in the city of Malaga

La investigación realizada se ha llevado a cabo en el marco de la Cátedra Tecnologías Emergentes para la Ciudadanía, Red de Cátedras Estratégicas del Vicerrectorado de Proyectos Estratégicos, Universidad de Málaga, y el Polo Digital, Ayuntamiento de Málaga.In recent years the urban public space has become the largest casual sports infrastructure in cities and suburbs. WHO establishes a direct relationship between the Active Healthy City, social cohesion of communities and public space. This approach provides a framework for research and work on the design of the city and urban space as support for this sport practice. Moreover, new technologies provide an opportunity to promote the sport in the city. “Malaga Activa” digital platform project is an initiative that wants to promote the informal sport practice on the urban public space (outside the regulated sports facilities) and healthy living in the neighborhoods of the city of Malaga. This paper presents the results of the first phase of the project identifying the active sport areas -those in which physical and casual sport activities take place-. It also includes a methodology and a performance test of the created digital platform, as well as an assessment of the experience and possible improvements to be incorporated in the successive phases of the project.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Perfluorodecalin/hydrocarbon systems prediction and correlation of liquid-liquid equilibrium data

Experimental binary, ternary and quaternary liquid-liquid equilibrium data for systems containing perfluorodecaline (PFD) and some hydrocarbons were determined. Binary NRTL, UNIQUAC and UNIFAC parameters were obtained, from the binary, the ternary and the quaternary experimental data: for the calculation of parameters from binary data a Newton-Raphson technique was used and the parameters so obtainedfor each temperature (T)-were linearly correlated with T and 1/T. Predicted binary, ternary and quaternary data were then compared with the experimental results; a Nelder-Mead method was used for the calculation of the binary parameters from ternary tie-line data. UNIFAC group parameters for the interaction CH2/CF2 and CH=CH2/CF2 were obtained. Attempts were made, and are discussed, to: correlate UNIFAC parameters with the number of carbon atoms and temperature; obtain a set of NRTL and UNIQUAC parameters yielding the overall best fit for the systems under consideration

Liquid-liquid equilibria for the system perfluorodecalin/1-heptene/n-heptane/n-hexane

Liquid-liquid equilibria for the quaternary system perfluorodecalln (PFD)/l-hepteneln-heptaneln-hexane at 288.15 K (type 111) and 298.15 K (type 11) and for the ternary systems PFDII-hepteneln-heptane, PFDII-hepteneln-hexane, and PFD/n -heptane/n-hexane at the same temperatures are reported. The experimental results are compared with values predicted by using the NRTL, the UNIQUAC, and the UNIFAC models

Liquid-liquid equilibria of systems containing perfluoromethylcyclohexane

Liquidliquid equilibria for the quaternary system perfluoromethylcyclohexane (PFMCH)1-heptenen-heptanen-hexane at 288.15 K and for the ternary systems PFMCH1-heptenen-heptane, PFMCH1-heptenen-hexane and PFMCHn-heptanen-hexane at 279.15 K and 288.15 K are reported. The experimental results are compared with predicted values calculated using the NRTL and the UNIQUAC models

Low-Cost Piezoelectric Sensors for Time Domain Load Monitoring of Metallic Structures During Operational and Maintenance Processes

The versatility of piezoelectric sensors in measurement techniques and their performance in applications has given rise to an increased interest in their use for structural and manufacturing component monitoring. They enable wireless and sensor network solutions to be developed in order to directly integrate the sensors into machines, fixtures and tools. Piezoelectric sensors increasingly compete with strain-gauges due to their wide operational temperature range, load and strain sensing accuracy, low power consumption and low cost. This research sets out the use of piezoelectric sensors for real-time monitoring of mechanical strength in metallic structures in the ongoing operational control of machinery components. The behaviour of aluminium and steel structures under flexural strength was studied using piezoelectric sensors. Variations in structural behaviour and geometry were measured, and the load and μstrains during operational conditions were quantified in the time domain at a specific frequency. The lead zirconium titanate (PZT) sensors were able to distinguish between material types and thicknesses. Moreover, this work covers frequency selection and optimisation from 20 Hz to 300 kHz. Significant differences in terms of optimal operating frequencies and sensitivity were found in both structures. The influence of the PZT voltage applied was assessed to reduce power consumption without signal loss, and calibration to μstrains and loads was performed.This research was funded by Basque Government, grant number KK-2019/00051-SMARTRESNAK and by the European Commission, grant number 869884- RECLAIM