We have developed a new parallel processor system specific for the MC analysis, to dramatically reduce the calculation time. Our parallel processor system is based on ring bus architecture. The RISC micro processor ch...
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A computer model was developed to establish the relationship between the two-dimensional (2D) and the three-dimensional (3D) parameters, specifically the number of particles and particle size distribution. The compute...
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A computer model was developed to establish the relationship between the two-dimensional (2D) and the three-dimensional (3D) parameters, specifically the number of particles and particle size distribution. The computer experiments were performed for both monodispersed and lognormally polydispersed systems. The model was based on a random distribution of a number of spherical grains in a cubic unit, with no intersection between the grains. The cubic unit was cut by a random plane and the number of particles which appeared in the section and the area fraction were measured. This procedure was repeated until the average number of particles and the average area fraction became constant. Finally, the 2D size distribution of the particles over all sections was obtained. It was concluded that the volume fraction is equal to the area fraction, irrespective of the particle size distribution, providing that the total number of measured 2D particles is large enough. As for the number of particles, an equation was found to calculate the number of 3D particles in a monodispersed system from the number of 2D particles and the volume fraction. However, in lognormally polydispersed systems the number of 3D particles could be calculated using the 3D mean and standard deviation, estimated from the 2D mean and standard deviation by a method specifically developed for the purpose. Finally, the method was applied to two ductile cast iron specimens and the applicability of the present model was verified.
Modeling and simulation of the solidification process are very important in order to predict the parameters which affect the casting properties,which in turn reduces the practical trials prior to production.A modifica...
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Modeling and simulation of the solidification process are very important in order to predict the parameters which affect the casting properties,which in turn reduces the practical trials prior to production.A modification to the squeeze casting process which a clear and is set between the plunger and die in order to avoid the Modeling and simulation of the solidification process are very important in order to predict the high resistance of the early formed solid *** amount of the chosen clearance is of great importance to the success of the *** clearance allows a small portion of the cast melt to back extrudes. The proposed expression that had been verified experimentally on Al-Si alloy castings.
The audible noise produced by three‐phase, squirrel‐cage induction motors, is caused by the space harmonics of the flux‐density distribution in the air gap of the machine. When the motor is supplied by a frequency ...
The formulation of a simple and effective pipe elbow element for the analysis of pipe bends is presented. The element is enhanced to capture the general shell behaviour of elbows. The formulation is based on the curve...
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The formulation of a simple and effective pipe elbow element for the analysis of pipe bends is presented. The element is enhanced to capture the general shell behaviour of elbows. The formulation is based on the curved beam theory incorporating shear as well as cross-section ovalization effects. The ovalization of the cross-section varies cubically along the element length. The formulation has been implemented in the computer program ELBOW and sample results are presented. The validity of the formulation is substantiated by comparison with other numerical and experimental results available in the literature.
The residual stress distribution in the surface region of solution treated and aged 7075 aluminium alloy workpieces that are orthogonally burnished under lubricated condition is determined using a deflection etching t...
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The residual stress distribution in the surface region of solution treated and aged 7075 aluminium alloy workpieces that are orthogonally burnished under lubricated condition is determined using a deflection etching technique. The residual stress at the surface is low compressive and increase rapidly with an increase in depth beneath the burnished surface to a maximum compressive then decreases gradually with further increase in depth becoming vanishingly small tensile or compressive. The maximum residual stress and depth of the stressed region increase in burnishing speed, force and an increase, to some extent, in burnishing time. The results are interpreted qualitatively in terms of the variations in the amount of surface region deformation produced by changes in burnishing conditions.
The effects of cutting speed, feed rate and depth of cut on the residual stress distribution in the machined surface region caused by milling of five different materials are determined using an electrolytic etching-de...
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The effects of cutting speed, feed rate and depth of cut on the residual stress distribution in the machined surface region caused by milling of five different materials are determined using an electrolytic etching-deflection technique. The analysis of the experimental data is carried out using response surface methodology (RSM). The results show that the residual stress is low tensile at the machined surface and increases with an increase in depth beneath the surface reaching a maximum tensile, then decreases with a further increase in depth, eventually becoming vanishingly small. The peak residual stress is found to be strongly dependent on both milling conditions and tensile strength of work material. A mathematical model correlating the process input parameters and their interactions with the residual stress is proposed.
Burnishing is a process of finishing metal by compressing its surface layer by the application of a highly polished and hardened tool. Burnishing, being an application of the cold working process, reduces the surface ...
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Burnishing is a process of finishing metal by compressing its surface layer by the application of a highly polished and hardened tool. Burnishing, being an application of the cold working process, reduces the surface roughness, increases the hardness of the surface layer which, in turn, improves the fatigue strength of the workpiece and improves its wear resistance. This paper presents an experimental investigation concerning the effect of different burnishing parameters on the surface finish and micro-hardness of the surface layer during a ball burnishing process. The analysis of the experimental data has been carried out using a response surface methodology to improve upon the reliability of the nature of the interaction between the process parameters. The effects of burnishing speed, feed, ball force and number of passes on the above-mentioned surface properties for 70 30 Cu-Zn alloy have been discussed. Two mathematical models correlating the process parameters and their interactions with the response parameters have been derived. These models can be used in selecting optimum burnishing process parameters.
In dieser Arbeit wird ein neues Verfahren angegeben, mit dem das optimale Über-setzungsverhältnis des Getriebes elektrischer Roboterantriebe berechnet werden kann. In diesen Rahmen wird die physikalische Bed...
In dieser Arbeit wird ein neues Verfahren angegeben, mit dem das optimale Über-setzungsverhältnis des Getriebes elektrischer Roboterantriebe berechnet werden kann. In diesen Rahmen wird die physikalische Bedeutung einer neuen Motorkonstanten aufgezeigt, die in Datenblättern im Zusammenhang mit der Kommutierungsgrenzkurve zur Charakterisierung der optimalen Leistungsfähigkeit des Motors und zur Wahl des optimalen Übersetzungsverhältnisses benutzt werden sollte. Weiterhin wird der Einfluβ der Führungsgröβenvorgabe auf die Wahl des optimalen Übersetzungsverhältinisses aufgezeigt. The principal performance parameter for a robot joint is torque. In the case of electrical actuation the available torque is used to support statically the arm and load. In practice there are also dynamic torque requirements associated with moving the load from point to point in an acceptable period of time with a given velocity profile. It is usually permissible to overload an electric motor to obtain the additional torque provided that the maximum allowable winding temperature is not exceeded. Therefore, an appropriate gearbox transmission ratio must to be selected to minimize the time required to perform a specified move distance with minimum motor power and the best performance of the joint drive. The object of this paper is to determine the optimum gear-box transmission ratio for industrial robot drives under consideration of the commutation limit curve of the dc servo motor and the velocity profile. The velocity profile after Bestehorn (dynamically smoother motion[1]) is considered. Minimum time for a given move distance is obtained when the optimal transmission ratio, i ges opt , equals. i ges opt = 0.357 C ϕ ̈ j ges A max C 2 ϕ ϕ L max KM M d b 2 3 Because optimal transmission ratio is proportional to the cube root of the move distance and the load, a transmission ratio can be chosen which is close to optimal for a fairly large range of the distance and load.
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