Numerical Modeling and Evaluation of PEM Used for Fuel Cell Vehicles

The present study sought to analyze a novel type of polymer membrane fuel cell to be used in vehicles. The performance of the fuel cell was evaluated by modeling the types of production–consumption heat in the anode and cathode (including half-reaction heat, activation heat, and absorption/desorption heat) and waterflood conditions. The meshing of flow channels was carried out by square cells and the governing equations were numerically discretized in the steady mode using the finite difference method followed by solving in MATLAB software. Based on the simulation results, the anodic absorption/desorption heat, anodic half-reaction heat, and cathodic activation heat are positive while the cathodic absorption/desorption heat and cathodic half-reaction heat show negative values. All heat values exhibit a decremental trend over the flow channel. Considering the effect of relative humidity, the relative humidity of the cathode showed no significant change while the anode relative humidity decreased along the flow channel. The velocity at the membrane layer was considerably lower, due to the smaller permeability coefficient of this layer compared to the gas diffusion and reactants (cathode) layers.

ENGLISH: ISLAMIC METHODOLOGY OF MOTIVATION: AN APPRAISAL IN THE LIGHT OF SEERAH

The recent developments observed in the world are owed to the efforts of human capacities and capabilities. Zeal, flair and enthusiasm of work people keep the pace of development in steady mode. However, over a period of time, human motivation to work starts decreasing. In the western world studies have been carried out to find out factors which affect human motivation to devise strategies to enhance work motivation among individuals. It has been observed that determinants of motivation are cultural specific. Moreover it is associated with the world view of human being. Islam is distinguished religion from other religions of the world and forms its own culture. Holy Prophet Muhammad (SAW) in his life time prepared a group of individuals who changed the socio-political scene of this world in few years. Their motivation level was un-parallel to anyone else. The current study explores methodologies of motivation used by the Prophet (SAW) to stimulate his companions. The originality and value of this study can be seen in the sense that it will provide basis for the formulation of motivational framework based on Islamic teachings. As a conclusion, team of researchers comprising of educationists, social scientists, and Islamic scholars must work together to find out framework of motivation in the present day environment.

Structure for interaction software process modules in the development of technological processes of cast

On the basis of the General criterion of quality the problem-oriented program technological algorithm for adjustment of technological parameters at the expense of reception of the characteristics investigated thermophysical properties of the profits providing the steady mode of imposing of hydrodynamic pressure before the beginning of crystallization of casting as a result of heating of profitable part of the interconnected elements «Gating system–casting» is developed. The software algorithm uses the means of computational experiment to determine the optimal values of the parameters in the development of cast processes. Optimization of the thermal regime is reduced to the analysis of the results of the studied thermophysical properties of top ingot due to the heating of the profitable part of the Gating-feeding system. The tested parameters are: temperature in top ingot in crystallized metal; wall thickness of top ingot; thermophysical reaction; the speed of the die casting liquid steel; the height of the heel of metal in top ingot.

Analysis of reservoir’s mass influence on the system free – surfaced liquid and spherical reservoir

Within the framework of combined motion the effect of ratio of masses of reservoir and liquid on the behavior of a free surface of liquid in the reservoir of spherical shape is studied. We suppose that liquid is ideal and it fills partially the reservoir. Mathematical modelling is done on the basis of the model, which takes into account combined character of nonlinear dynamics of liquid and the reservoir. Examples were done based on mathematical model of combined motion of liquid in spherical reservoir and free-surfaced liquid under harmonic force disturbance in horizontal direction. Two cases of the ratio of masses in the system are considered. First, the mass of the reservoir is 5 times less than the mass of the liquid; the mass of the reservoir is 5 times greater than the mass of the liquid. In order to identify specific features of the system behavior, the results were compared with the results for liquid behavior in cylindrical and conical reservoirs. It was ascertained that mass increasing has no tendency of converging to a steady mode of motion, which was confirmed experimentally. Distinctions of manifestation of nonlinear processes for the below-resonance, near-resonance and above-resonance modes are shown. We note manifestation of nonlinear effects such as modulation, the presence of high-frequency normal modes of oscillations, antiresonance and drift of the mean of oscillations.

Centrifugal instabilities in an experimental open cavity flow

We present an experimental parametric study of spanwise centrifugal instabilities in an open cavity flow. We show that the mode selected at threshold depends on the cavity streamwise aspect ratio. For small aspect ratio, a steady mode is enhanced, while travelling waves are observed for large aspect ratio. The bifurcation is found to be supercritical for all configurations. Sidewall effects are shown to generate secondary flows that carry the vortical patterns. Spanwise confinement enhances the family of steady modes relative to the family of oscillatory modes. These results are discussed with respect to predictions from linear stability analyses and other flows developing centrifugal instabilities.

Simulation of the Evolution of Pathological Processes in Parkinson´s Disease

In medicine, there are very large numbers of models of different pathological processes. Thus, models of the evolution of pathologies, in particular, in the clinic of nervous diseases absent altogether. This work presents an example of mathematical modeling the development of pathology in the human body in the form of transition from postural tremor to periodic tremor Parkinson´s and further to a rigid form. The appearance of periodicity in the characteristics of the neuromuscular system corresponds to the pathological phenomenon, for example, Parkinson´s disease. The authors note the similarity of tapping in relatively healthy person with a tremor of a patient with Parkinson´s disease from the position of the phase portraits. At high excitations from the striatum in patients with Parkinson´s disease (in models is Ш=410 u.e.) in the cluster of the neuromuscular system comes rigid phase and in the effector system there is a severe form of parkinsonism, the muscles can no longer perform any movements. In this case the timebase activity of effector organs moves in a steady mode and takes some constant value. The simulation results suggest the high consistency of the obtained results with real signals recorded by the subjects in different conditions. For various indicators of the functional systems of the human body, it is necessary to find the coefficients b and ud directionally.