The effect of particle shape on the angle of repose test based calibration of discrete element models

Discrete element method (DEM) is a Lagrangian description based numerical technique used for modelling the mechanical behavior of granular materials. For using the DEM model, the micromechanical parameter values used in the governing equations must be determined beforehand. This is the so-called calibration problem. In most of the cases these micromechanical parameters cannot be directly measured, their values must be systematically changed until the modeled macro behavior of the granular assembly will be the same, as the real-life behavior. In this article we propose the simplest possible calibration method, the so-called angle of repose test for application in case of agricultural crop product related problems. We examine the effect of particle shape on the value of angle of repose, ad give statistically acceptable empirical function to describe this dependence mathematically

De-Icing of Road Surfaces (Bridges) with Heat

The rapid changes of weather, like sudden cooling, especially when it is comes with moisture can cause dangerous traffic situations (personal injuries and significant property damage) for those who use roads, bridges, interchanges. These weather conditions are responsible for the most of winter traffic jams. The maintenance of these roads means mechanical removal of snow or scattering of surfaces (to decrease freezing of surfaces).The usage of salt is disadvantageous because it causes corrosion, it is texture wrecking and it is harmful to the environment. The bridges and overpasses cool down earlier than the average roads. The road maintainers have the responsibility to guarantee the safe transport on winter roads. Tasks of road maintainers (prevention): – bridges, overpasses; – airport roads, highways; – hilly bus routes; – roads of residential institutions (hospitals, food supplies). In developed countries (Japan, USA, Germany, etc.) already 20-25 years ago more environmental friendly solutions were evolved. In our work we analyse the heating of a non-identified real bridge (and overpass) with additional calculations. This article was written with the help of a TÁMOP 4.2.1.B-11/2/KMR-2011- 0003 „INCREASING THE QUALITY OF LEARNING AND RESEARCH” progra

The situation of application of wind power plant in the world and in Hungary

The worldwide wind capacity reached 282’275 Megawatt, out of which 44’609 Megawatt were added in 2012, more than ever before. In Hungary the current wind energy capacity is 330MW, built of modern units, which are designed for the Hungarian wind circumstances. Because of this energy production is very good (740 GWh/year) and the capacity factor (24.1%) is good as well (the 4th best in Europe in 2012). With this we save approx. 220 million m3 /year natural gas whilst we avoid ~400 000 tons of CO2 emission. It is a fact that wind power plants (after the return of investment -9-10 years-) produce cheap energy. From financial side wind power plant utilization is one of the most perspective investments. Our analysis points out that the ambitious plan of Hungary for 2020 (the increasing of renewable energy utilization) is unlikely to be met without wind energy utilization. This article was written with the help of a TÁMOP 4.2.1.B-11/2/KMR-2011- 0003 „INCREASING THE QUALITY OF LEARNING AND RESEARCH” progra

Clayton Copula as an Alternative Perspective of Multi-Reaction Model

This study proposes to assess the effect of some relevant parameters of biomass pyrolysis on the numerical solutions of nthorder distributed activation energy model (DAEM) or multi reaction model (MRM). The two-step process mechanisms of pyrolysis is described by replacing the initial distribution function of f (E) with the Clayton copula. The upper limit (E∞) of ‘dE’ integral, activation energy (A), heating rate (m), and the shape and scale parameters of bivariate distribution function. Temperature ramp rate is assumed to vary linearly with time. Thermo-analytical data is obtained with the help of thermogravimetric (TG) analysis. Asymptotic technique is adopted to approximate double exponential and bivariate distribution function f (E1, E2), where E1and E2are the activation energies for bivariate scheme