Applied Mechanics and Materials Vols. 110-116

Abstract: This paper introduces the phenomenon of self-similar network, and then it gives the mathematical definition of self-similar and analysis for the network performance. Based on this, this paper puts forward a new mapping model of ON / OFF and the chaotic mapping model based on the ideas. The model simplifies the chaotic mapping function mapping model by choosing a random variable with a linear piecewise function. The model length is subject to the state heavy-tailed. This model can capture network traffic self-similarity.

Abstract: The genetic algorithm discussed in this paper for project scheduling solution to this problem can be obtained the near optimal schedule programs. This has established the objective function and constraints that have a certain scope; it requires the duration of each process that is determined in advance for enterprises. If the project is more familiar with the history with more experience, and more complete database, the project environment can be controlled well. It can accurately determine the time with the construction plan, construction process and the optimization method with the good trial.

Abstract: —This paper explores a new method to find most reliable lifetime distribution function of systems, via an applied heuristic model. In most operating systems which complicity of system obligates high degree of reliability, this model will be use to propose a more appropriate reliability function between lifetime distribution based and another that is based on relevant Extreme Value distribution. A numeric study will be reviewed to clear the concepts of this paper.

Abstract: — The effects of fuel injection angles on the average diameter of fuel propulsive droplets sizing and efficient mass fraction in combustion chamber of a ramjet are numerically investigated in the present paper. We named the mass of fuel vapor inside the flammability limit as the efficient mass fraction. In order to investigate the effects of fuel injection angle on the mean diameter of fuel propulsive droplets sizing, there are conducted two sets of calculation. The fuel injection angle of part I is varied as 30°, 45°, and 60° in flow direction, also the fuel injection angle of part II is counter-flow and varied as 0°, 30°, 45° and 60° to examine its effects on the fuel droplets and fuel/air mixing phenomena, as well as we have increased the fuel injection velocity from 40 to 45, 50 and 55m/s respectively and we have inspected the needed data again. To fulfill the calculation we used a modified version of KIVA-3V.

Abstract: — In this paper, our goal is to simulate abrasion resistance material. We therefore need a robust algorithm to model this phenomenon which is a kind of large frictional contact problem. In order to reach to our aim, we have proposed a new method to impose contact constraints in eXtended Finite Element Method (XFEM) framework. In this algorithm, we have modeled large sliding contact problems by using the Node To Segment (NTS) concept. Furthermore, friction between two sliding interface has been modeled based on the Coulomb friction law. In addition, the penalty method which is the most convenient way of imposing non-penetration constraints has been employed. In our algorithm, new Lagrangian shape functions have been used to solve the problems of the conventional Heaviside enrichment function. Finally, a numerical simulation has been delivered to prove the accuracy and capability of our new algorithm.

Abstract: In this paper, the flow characteristics and heat transfer over two equal square cylinders which are placed in tandem arrangement, are investigated numerically. The simulations are performed for a Reynolds number range varying from 1 to 200 and spacing between the cylinders is five widths of the cylinders. The calculations are carried out on a finite volume code for both steady and unsteady incompressible laminar flow in the two dimensional regime. In this study, the instantaneous and mean streamlines and isotherm patterns for different Reynolds numbers are presented. In addition, the effect of Reynolds number on the flow patterns around the cylinders are in detail presented. In addition, the quantities such as pressure and viscous drag coefficients and pressure coefficients are presented.

Abstract: low pumps have been developed for classical applications in Engineering and medicine. They are vital instruments in areas such as Biology where the applications demand many such devices in miniaturized form to handle life saving fluids and drugs. The aim of this paper is to develop a new bio-mimic fluid pump, designed to achieve miniaturization in its size and volume. A new actuation technique is proposed which pumps the fluid based on the principle of flow due to pressure difference created by varying the cross-section of a flexible tube. The novelty and advantage being, no external pressurizing device is needed and the flow can be made bidirectional. This is in general not possible in normal or traditional pumps. Use of SMA wires as actuators helps in keeping the size and weight of the device as low as possible. The working principle of the device and the conceptual design are discussed. Mathematical model, relating the flow parameters required for controlling the device, and analytical results obtained from such relations are presented.

Abstract: This research was aimed to improve an inspector’s performance on the training through 3D model by motivation technique. The subjects were divided into 3 groups; the control, the feedback training, and feedback training with reward groups. The subjects participated in the last group would get rewards or punishments such as money given or deducted during the test with 3D model software with Thai characters and Roman characters representing defects and backgrounds. According to the experiment, the performance in terms of speed and accuracy in detecting defects in training with reward group increased. In other words, feedback with motivation training could make visual inspectors spend less time detecting defects to their minimum because motivation attracted them in the experiment. Therefore, the time spent seeking defects in this group decreased. The performance of training with reward group is higher than other groups which showed the statistical significance at the .01 level.

Abstract: A new linear yield criterion, referred to as Equal Area (EA) yield criterion, was derived in Haigh Westergaard stress space based on the projection area of its yielding locus on the π-plane equal to the area of von Mises yielding circle. Under the plane stress and strain conditions the crack tip plastic zone dimensions were calculated based on EA yield criterion and compared with those calculated according to the Tresca and von Mises yield criteria. The results showed that the crack tip plastic zone based on EA yield criterion is similar to that based on von Mises yield criterion, but is much different to that based on Tresca yield criterion. Meanwhile, the influences of Poisson ratio and loading parameter on the crack tip plastic zone were investigated based on EA yield criterion.

Abstract: Multi objective optimizing of machining processes is used to simultaneously achieve several goals such as increased product quality, reduced production time and improved production efficiency. This article presents an approach that combines grey relational analysis and regression modeling to convert the values of multi responses obtained from Taguchi method design of experiments into a multi objective model. The proposed approach is implemented on turning process of St 50.2 Steel. After model development, Analysis of Variance (ANOVA) is performed to determine the adequacy of the proposed model. The developed multi objective model is then optimized by simulated annealing algorithm (SA) in order to determine the best set of parameter values. This study illustrates that regression analysis can be used for high precision modeling and estimation of process variables.