In this work, an indirect solar dryer integrated thermal storage for drying figs. (Ficuscarica) is studied numerically. Unsteady turbulent airflow and heat transfer through a two-dimensional model is carried out for a typical day of August under the climatic conditions of Tlemcen (Algeria). Effects of air inlet size and thickness of the packed bed on the dynamic and thermal behaviors of the dryer with and without packed bed have been discussed. The study shows that: (1) Increase the inlet size from 0.04 m to 0.10 m can accelerate the extraction of air by about 13% and reduce the maximum crops temperature by about 14%. (2) The packed bed can reduce the mass flow rate extracted by 22% and the fluctuations of air temperature by 1.3%. (3) A packed bed with a thickness of 0.15 m can extend the operating time of the dryer up to 23%.
An analytical solution is presented to a doubly mixed boundary value problem of an elastic layer partially resting on a rigid smooth base. A circular rigid punch is applied to the upper surface of the medium where the contact is supposed to be smooth. The case of the layer with a cylindrical hole was considered by Toshiaki and all . The studied problem is reduced to a system of dual integral equations using the Boussinesq stress functions and the Hankel integral transforms. With the help of the Gegenbauer formula we get an infinite algebraic system of simultaneous equations for calculating the unknown function of the problem. The truncation method is used for getting the system coefficients. A closed form solution is given for the displacements, stresses and the stress singularity factors. The stresses and displacements are then obtained as Bessel function series. For the numerical application we give some conclusions on the effects of the radius of the punch with the rigid base and the layer thickness on the displacements, stresses, the load and the stress singularity factors are discussed.
Traveling in remote areas at nights is very risky and tire getting puncture at that time is dangerous. To avoid any of this complications a sub wheel system is installed in the vehicle. Sub wheels helps to go to required destination and change the puncture wheel. The tires used in this system are mold tires so they don’t get affected by the road conditions. The sub wheel is operated by means of a hydraulic system. Power for this sub wheel is provided from the engine placed in the back of the vehicle. This is system is very useful heavy weight vehicle which travel in difficult terrain (army vehicles). The height of the car is increased so that Sub wheels won’t affect the chassis or the engine. This type of system is used in le24race but they only use hydraulic system to lift the car. The advantage of this system is its user friendly and effective to use. By pressing a button required sub wheel comes down and start to function. By using CATIA a diagram of this system is drawn to check it’s various forces acting on it.
This article focuses on the synthesis of a steering mechanism that exactly meets the requirements of steering geometry. It starts from reviewing the four-bar linkage, then discusses the number of points that a common four-bar linkage could precisely trace at most. After pointing out the limits of a four-bar steering mechanism, this article investigates the turning geometry for steering wheels and proposes a steering mechanism using servo motors and ARDUINO board. The pitch curves, addendum curves, dedendum curves, tooth pro les and transition curves of the noncircular gears are formulated and designed. Finally, kinematic simulations are executed to demonstrate the target of design
In this work, the finite element method was used to determine the stress intensity factors as a function of crack propagation in metal matrix composite structure, A three-dimensional numerical model was developed to analyze the effect of the residual stresses induced in the fiber and in the matrix during cooling from the elaboration temperature at room temperature on the behavior out of the composite. Added to commissioning constraints, these internal stresses can lead to interfacial decohesion (debonding) or damage the matrix. This study falls within this context and allows cracks behavioral analysis initiated in a metal matrix composite reinforced by unidirectional fibers in ceramic. To do this, a three-dimensional numerical model was analyzed by method of finite element (FEM). This analysis is made according to several parameters such as the size of the cracking defects, its propagation, its interaction with the interface, the volume fraction of the fibers (the fiber-fiber interdistance), orientation of the crack and the temperature.
In this work, we have investigated the effect of the natural Kenaf reinforcement on the improvement of the interfacile bond between two types of epoxy and Polypropylene (PP) matrix. Our genetic model is based on Weibull's probabilistic models and on Cox's interface model. The moisture content for each material is determined by Fick's law. Our simulation results show that the most resistant interface is that of Kenaf-Polypropylene compared to the other interfaces. This result coincides perfectly with the experimental data found by Paul Wambua et al. Which have shown that Kenaf is a promoter fiber for the improvement of the mechanical properties of biocomposite used in the field of civil engineering.
A two-scale asymptotic analysis coupled with the spatially periodic fundamental solutions are used for analyzing diffraction of elastic bulk waves propagating in anisotropic media containing periodic inclusions or voids. Explicit equations are derived for the scattering cross sections and velocities of bulk waves propagating in spatially periodic media with arbitrary elastic anisotropy.
This work investigates drilling of small holes of Ø 3 mm on duplex Stainless Steel. Its machinability index is very low (0.66) as compared to other steels, hence Electrical Discharge Machine is used. The input parameters are Current, Spark Gap & Di electric Pressure. Each input parameter is considered for 3 levels. Therefore total number of experiments is 3×3×3 – 27. To reduce the number of runs, Taguchi L9 orthogonal array is used, which is having advantage of maximum and minimum trial runs in its design. The output response is metal removal rate. To find the best operating parameter, the regression model of ANOVA is given to input of MAT Lab-Genetic Algorithm. The experimental results indicated that models are significant. The test result indicated that the contributions of current is 42.42%, Di electric pressure is 35.36% and Spark gap is 1.93% on metal removal rate. From Genetic Algorithm it is observed among three levels of factors, lower value of current and Di electric pressure produced maximum metal removal rate. The SS 2205 has wide variety of applications such as high pressure components, control valves etc., which are having large number of components to it. Hence performing micro holes on such high hardness alloy is useful.
Ahmed Body is a standard and simplified shape of a road vehicle that's rear part has an important role in flow structure and it's drag force. In this paper flow control around the Ahmed body with the rear slant angle of 25° studied by using the plasma actuator system situated in middle of the rear slant surface. Experiments conducted in a wind tunnel in two free stream velocities of U = 10 m/s and U = 20 m/s using steady and unsteady excitations. Pressure distribution and total drag force was measured and smoke flow visualization carried out in this study. The results showed that at U = 10 m/s using plasma actuator suppress the separated flow over the rear slant slightly and be effective on pressure distribution. Also total drag force reduces in steady and unsteady excitations for 3.65% and 2.44%, respectively. At U = 20 m/s, using plasma actuator had no serious effect on the pressure distribution and total drag force.
Resistance spot welding is a comparatively clean and efficient welding process that is widely used in sheet metal joining. This process involves electrical, thermal and mechanical interactions. Resistance spot welding primarily takes place by localized melting at the interface of the sheets followed by its quick solidification under sequential control of water cooled electrode pressure and flow of required electric current for certain duration. In this experimental work the tensile tests and the spot weld diameter were studied. The objectives of this analysis is to understand the physics of the process and to show the influence of the electrical current, weld time and the type material in resistance spot welding process.