The allocation of entrepreneurial effort and its implications on economic growth

The problem to allocate effort to innovation activities is defined and modelled for any single entrepreneur according to its propensity to innovate, which combines pure innovation and rent-seeking strategies. The allocation problem is solved both analytically and via simulation. The individual decisions measured in units of innovation are then aggregated to calculate the innovation quantity for a given population based on the distribution of heterogeneous entrepreneurs. The entrepreneurship rate and the implications for economic growth are also quantified. Consequently, policy makers should focus on reducing the entry barriers and the costs of production in order to stimulate the entrepreneurial activity and maximize the innovation quantity. They should also foster the attitude and propensity towards innovatio

Simulation of a solar funnel cooker using MATLAB

A software for the calculation of the radiation heat transfer in solar funnel cookers by means of the radiosity method has been developed in Matlab. The software has been used to study a folding solar cooker. The cooker geometry is discretized using a triangular mesh where a piecewise constant approximation is assumed for the radiosity function. Form factors, including self-occlusions, are calculated by properly refining the triangular mesh. The concentration factor of the solar cooker is estimated as a function of its position and orientation with respect to that of the Sun.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Entrepreneurial effort and economic growth

Entrepreneurs allocate resources among different activities that generates a profit; in particular, in this paper entrepreneurs consider at each instant of time both innovation and rent-seeking as alternative sources of profit. The consequences in terms of economic growth are obviously quite different: the higher the amount of innovations in the economy the higher the rate of economic growth and vice versa. What are the determinants of these different entrepreneurial behavior? Is there anything in the nature of entrepreneurs that essentially distinguishes between innovators and rent seekers? A main claim of this paper is that differences among entrepreneurs are not essential but of degree: all of them are in fact profit-seekers and the only difference is to be found in their attitude towards innovation as a source of profit. In this sense entrepreneurial effort is defined and modelled for each entrepreneur according to its propensity to innovate and the corresponding Entrepreneurial Problem (EP) is posed and solved both analytically and via simulation in terms of profit maximization. The individual decisions measured in units of innovation are then aggregated to calculate the innovation quantity for a given population based on the distribution of heterogeneous entrepreneurs. The entrepreneurship rate and the implications for economic growth are also modelled. Consequently, policy makers should focus on reducing the entry barriers and the costs of production in order to stimulate the entrepreneurial activity and maximize the innovation quantity

Virtual reality models for the structural assessment of architectural heritage buildings

Peer ReviewedPreprin

Morphological Functions with Parallel Sets for the Pore Space of X-ray CT Images of Soil Columns

During the last few decades, new imaging techniques like X-ray computed tomography have made available rich and detailed information of the spatial arrangement of soil constituents, usually referred to as soil structure. Mathematical morphology provides a plethora of mathematical techniques to analyze and parameterize the geometry of soil structure. They provide a guide to design the process from image analysis to the generation of synthetic models of soil structure in order to investigate key features of flow and transport phenomena in soil. In this work, we explore the ability of morphological functions built over Minkowski functionals with parallel sets of the pore space to characterize and quantify pore space geometry of columns of intact soil. These morphological functions seem to discriminate the effects on soil pore space geometry of contrasting management practices in a Mediterranean vineyard, and they provide the first step toward identifying the statistical significance of the observed differences

Parallel sets and morphological measurements of CT images of soil pore structure in a vineyard

Important physical and biological processes in soil-plant-microbial systems are dominated by the geometry of soil pore space, and a correct model of this geometry is critical for understanding them. We analyze the geometry of soil pore space with the X-ray computed tomography (CT) of intact soil columns. We present here some preliminary results of our investigation on Minkowski functionals of parallel sets to characterize soil structure. We also show how the evolution of Minkowski morphological measurements of parallel sets may help to characterize the influence of conventional tillage and permanent cover crop of resident vegetation on soil structure in a Spanish Mediterranean vineyard

Fractal parameters of pore space from CT images of soils under contrasting management practices

Soil structure plays an important role in flow and transport phenomena, and a quantitative characterization of the spatial heterogeneity of the pore space geometry is beneficial for prediction of soil physical properties. Morphological features such as pore-size distribution, pore space volume or pore?solid surface can be altered by different soil management practices. Irregularity of these features and their changes can be described using fractal geometry. In this study, we focus primarily on the characterization of soil pore space as a 3D geometrical shape by fractal analysis and on the ability of fractal dimensions to differentiate between two a priori different soil structures. We analyze X-ray computed tomography (CT) images of soils samples from two nearby areas with contrasting management practices. Within these two different soil systems, samples were collected from three depths. Fractal dimensions of the pore-size distributions were different depending on soil use and averaged values also differed at each depth. Fractal dimensions of the volume and surface of the pore space were lower in the tilled soil than in the natural soil but their standard deviations were higher in the former as compared to the latter. Also, it was observed that soil use was a factor that had a statistically significant effect on fractal parameters. Fractal parameters provide useful complementary information about changes in soil structure due to changes in soil management. Read More: http://www.worldscientific.com/doi/abs/10.1142/S0218348X14400118?queryID=%24%7BresultBean.queryID%7D

Volume, Surface, Connectivity and Size Distribution of Soil Pore Space in CT Images: Comparison of Samples at Different Depths from Nearby Natural and Tillage Areas

The study of soil structure, i.e., the pores, is of vital importance in different fields of science and technology. Total pore volume (porosity), pore surface, pore connectivity and pore size distribution are some (probably the most important) of the geometric measurements of pore space. The technology of X-ray computed tomography allows us to obtain 3D images of the inside of a soil sample enabling study of the pores without disturbing the samples. In this work we performed a set of geometrical measures, some of them from mathematical morphology, to assess and quantify any possible difference that tillage may have caused on the soil. We compared samples from tilled soil with samples from a soil with natural vegetation taken in a very close area. Our results show that the main differences between these two groups of samples are total surface area and pore connectivity per unit pore volume

Structural and numerical identifiability of thermal resistances in plate fin-and-tube heat exchangers using manufacturer catalog data

Plate fin-and-tube heat exchangers, commonly known as heating/cooling coils, are widely used in HVAC systems to transfer heat to or from air. A problem of practical interest in coil simulation is to identify the thermal resistances on the air and liquid sides using manufacturer catalog data. Manufacturers rarely provide detailed information (geometry and circuitry) of the coils they sell or install in factory-made equipment such as air handling units or fan-coils; they just report the performance of the coil at a few typical operating conditions. This paper examines whether it is mathematically possible to back-calculate the thermal resistances on the air and liquid sides using a set of performance data that is disturbed by noise (e.g. measurement errors) and consists of operating cases in which none of the two thermal resistances can be neglected. The first part of the paper discusses the structural identifiability problem, that is, the mathematical possibility of fitting Nusselt-type correlations for air and liquid, as well as a constant resistance for the wall. The second part of the paper discusses the possibility of calculating the numerical value of the parameters of the Nusselt correlations (constant or constant and exponent) using noisy data. The analysis is applied to a typical coil, which is simulated by means of a mathematical modelUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech