A note on the combustion of blends of diesel and soya, sunflower and rapeseed vegetable oils in a light boiler

Producción CientíficaThis paper deals with the study of the vegetable oils (VO) used as fuel for heating. The properties of sunflower, rape and soya oils are studied and these are compared with the properties of C-diesel fuel (used for heating domestic purposes in Spain). The mixtures of VO and diesel are studied and characterized and, finally, the results of a series of combustion trials of the mixtures in a conventional heating installation with a mechanical pulverization burner are presented. The results show that viscosity of VO limits the use of blends up to 40% of them, and the oxygen present in their structures contributes to an efficiency gai

Simulation of Harmonic Oscillators on the Lattice

[EN] This work deals with the simulation of a two¿dimensional ideal lattice having simple tetragonal geometry. The harmonic character of the oscillators give rise to a system of second¿order linear differential equations, which can be recast into matrix form. The explicit solutions which govern the dynamics of this system can be expressed in terms of matrix trigonometric functions. For the derivation we employ the Lagrangian formalism to determine the correct solutions, which extremize the underlying action of the system. In the numerical evaluation we develop diverse state¿of¿the¿art algorithms which efficiently tackle equations with matrix sine and cosine functions. For this purpose, we introduce two special series related to trigonometric functions. They provide approximate solutions of the system through a suitable combination. For the final computation an algorithm based on Taylor expansion with forward and backward error analysis for computing those series had to be devised. We also implement several MATLAB programs which simulate and visualize the two¿dimensional lattice and check its energy conservation.This work has been supported by the Spanish Ministerio de Economia y Competitividad, the European Regional Development Fund (ERDF) under grant TIN2017-89314-P, and the Programa de Apoyo a la Investigacion y Desarrollo 2018 (PAID-06-18) of the Universitat Politecnica de Valencia under grant SP20180016.Tung, MM.; Ibáñez González, JJ.; Defez Candel, E.; Sastre, J. (2020). Simulation of Harmonic Oscillators on the Lattice. Mathematical Methods in the Applied Sciences. 43(14):8237-8252. https://doi.org/10.1002/mma.6510S823782524314Dehghan, M., & Hajarian, M. (2009). Determination of a matrix function using the divided difference method of Newton and the interpolation technique of Hermite. Journal of Computational and Applied Mathematics, 231(1), 67-81. doi:10.1016/j.cam.2009.01.021Dehghan, M., & Hajarian, M. (2010). Computing matrix functions using mixed interpolation methods. Mathematical and Computer Modelling, 52(5-6), 826-836. doi:10.1016/j.mcm.2010.05.013Kazem, S., & Dehghan, M. (2017). Application of finite difference method of lines on the heat equation. Numerical Methods for Partial Differential Equations, 34(2), 626-660. doi:10.1002/num.22218Kazem, S., & Dehghan, M. (2018). Semi-analytical solution for time-fractional diffusion equation based on finite difference method of lines (MOL). Engineering with Computers, 35(1), 229-241. doi:10.1007/s00366-018-0595-5Paterson, M. S., & Stockmeyer, L. J. (1973). On the Number of Nonscalar Multiplications Necessary to Evaluate Polynomials. SIAM Journal on Computing, 2(1), 60-66. doi:10.1137/0202007Sastre, J., Ibáñez, J., Defez, E., & Ruiz, P. (2011). Efficient orthogonal matrix polynomial based method for computing matrix exponential. Applied Mathematics and Computation, 217(14), 6451-6463. doi:10.1016/j.amc.2011.01.004Higham, N. J. (2008). Functions of Matrices. doi:10.1137/1.9780898717778Sastre, J., Ibáñez, J., Defez, E., & Ruiz, P. (2011). Accurate matrix exponential computation to solve coupled differential models in engineering. Mathematical and Computer Modelling, 54(7-8), 1835-1840. doi:10.1016/j.mcm.2010.12.049Serbin, S. M., & Blalock, S. A. (1980). An Algorithm for Computing the Matrix Cosine. SIAM Journal on Scientific and Statistical Computing, 1(2), 198-204. doi:10.1137/0901013Ruiz, P., Sastre, J., Ibáñez, J., & Defez, E. (2016). High performance computing of the matrix exponential. Journal of Computational and Applied Mathematics, 291, 370-379. doi:10.1016/j.cam.2015.04.001Higham, N. J. (1988). FORTRAN codes for estimating the one-norm of a real or complex matrix, with applications to condition estimation. ACM Transactions on Mathematical Software, 14(4), 381-396. doi:10.1145/50063.21438

Nonlocal and nonlinear evolution equations in perforated domains

In this work we analyze the behavior of the solutions to nonlocal evolution equations of the form $u_t(x,t) = \int J(x-y) u(y,t) \, dy - h_\epsilon(x) u(x,t) + f(x,u(x,t))$ with $x$ in a perturbed domain $\Omega^\epsilon \subset \Omega$ which is thought as a fixed set $\Omega$ from where we remove a subset $A^\epsilon$ called the holes. We choose an appropriated families of functions $h_\epsilon \in L^\infty$ in order to deal with both Neumann and Dirichlet conditions in the holes setting a Dirichlet condition outside $\Omega$. Moreover, we take $J$ as a non-singular kernel and $f$ as a nonlocal nonlinearity. % Under the assumption that the characteristic functions of $\Omega^\epsilon$ have a weak limit, we study the limit of the solutions providing a nonlocal homogenized equation

Measuring Spatial Dynamics in Metropolitan Areas

This paper introduces a new approach to measuring neighborhood change. Instead of the traditional method of identifying “neighborhoods†a priori and then studying how resident attributes change over time, our approach looks at the neighborhood more intrinsically as a unit that has both a geographic footprint and a socioeconomic composition. Therefore, change is identified when both as- pects of a neighborhood transform from one period to the next. Our approach is based on a spatial clustering algorithm that identifies neighborhoods at two points in time for one city. We also develop indicators of spatial change at both the macro (city) level as well as local (neighborhood) scale. We illustrate these methods in an application to an extensive database of time-consistent census tracts for 359 of the largest metropolitan areas in the US for the period 1990-2000.

The suitability of a DRG casemix system in the Maltese hospital setting

The healthcare system in Malta is financed through global budgets and healthcare is provided free at the point of use. This paper is a first attempt to examine the feasibility of introducing a Diagnosis Related Groups casemix system for Malta, not necessarily for payment and funding purposes, but as a tool to help describe, manage and measure resource use. This is particularly challenging in view of the constraints and characteristics of a small state country. The study evaluates the applicability of the MS-DRG (Version 27.0) Grouper to describe acute hospital activity on the island. The classification of 151,615 admissions between 2009-2011 resulted in 636 DRG categories. Around half of these DRGs accounted for 99% of the total activity at the hospital, while 296 DRG categories had fewer than 15 cases over the period. Patient length of stay is used to explain resource use and the Coefficient of Multiple Determination obtained was of 0.19 (improving to 0.25 when a number of trimming algorithms were applied). A good proportion of the resulting DRGs had a Coefficient of Variation, which indicates a low degree of variability within the obtained DRG groups. This presents good evidence to support the introduction of a DRG system in Malta particularly in view of the recent drive towards more public-private partnerships and legislation on cross-border patient treatment

Combustion of Soya Oil and Diesel Oil Mixtures for Use in Thermal Energy Production

Producción CientíficaIn August 2005, Spain approved the Plan for Renewable Energy Sources for the period 2005-2010 (P.E.R.), including co-combustion installations. Co-combustion in the P.E.R. aims to increase power output by 12,185.3 GWh in five years and shows great interest in studies of the combustion of mixtures of fossil and bio-combustible fuels. This paper presents studies of the co-combustion of soya oil and diesel for thermal heating. The paper begins with a characterization of soya oil as well as mixtures of this oil, with diesel, as fuels. The combustion of the soya oil mixtures and diesel is made in an installation, where the pressure of injection as well as the air volume of the burner can be changed. The obtained results inside to be the environmental average legislation and a greater efficiency of combustion is found. The conclusions show that the use of mixtures of soya oil and Diesel for producing thermal energy in conventional equipment is feasible

Les introductions d'espèces dans le milieu aquatique. Le contexte biogéographique : aspects généraux et paléohistoire

Les grandes étapes de l'histoire du globe et leurs conséquences sur la distribution géographique du monde vivant sont exposées. 1. Tectonique des plaques. Mise en place des continents et des espaces océaniques depuis l'ère primaire. Les derniers mouvements tectoniques de l'ère tertiaire entraînent en Europe la mise en place et l'individualisation des grands bassins hydrographiques (Rhin, Danube, Rhône). 2. Fluctuations climatiques de la fin du Tertiaire et du Quaternaire. Les glaciations ont entraîné d'importants changements des niveaux des eaux marines, qui ont eu des répercussions sur le monde dulçaquicole : connexions rendues possibles lors des transgressions, isolats induits par les régressions. 3. L'homme en Europe après le Würm. De chasseur-cueilleur, l'homme devient, il y a environ 14 000 ans, cultivateur-éleveur. Il s'entoure d'espèces domestiquées dont certaines d'origine lointaine qu'il a introduites. Selon ses activités agricoles et ses migrations, de nombreuses espèces opportunistes s'introduisent dans ses cultures. Les fleuves jouent un important rôle de couloir de pénétration. En conclusion, introductions, réintroductions, renforcement de populations sont toujours d'actualité, y compris et surtout pour les espèces aquatiques