Advanced Materials Research Vols. 201-203

Abstract: The unsteady viscous flow of the supersonic jet element (SJE) was simulated numerically based on CFD technology. A dual time-stepping scheme and AMG scheme were employed to solve the unsteady flows in SJE, and the reasons of thrust fluctuation during the wall-attachment state of SJE are found out. Based on the pressure cloud and streamlines, the vortices generated by the unsteady flow on attached wall had also been investigated and drawn some conclusions.

Abstract: When using graph theory to conduct intelligent design for kinematic structure enumeration, the isomorphism identification of graphs is an important and complicated problem. In this paper, the methodology of transferring isomorphism identification into optimization issue was introduced. Then the recent development of applying advanced optimal methods for isomorphism identification was reviewed, the advantages and disadvantages of there methods were discussed.

Abstract: A 1arge-scale tumble rather than swirl would exist in the cylinder in the case of two valves’ opening in a four-valve engine. A strong swirl was generated when one valve is closed, but the flow capacity was less than that of two valves opening. In order to change it, achieving different lifts of valves (DLV) was present. Both tumble and swirl would exist in the cylinder in the case of different lifts of two intake valves, and flow capacity will hardly change.

Abstract: As one of the important questions in the design of hydraulic manifold block — connection order of network, give a solution based on genetic algorithm. Genetic algorithm is the common effective intelligent optimal algorithm and suitable for solving a large combinatorial optimal problems. Gene encoding of ordinal representation, single-point crossover strategy and adaptive mutation strategy are used in the design of genetic manipulation.

Abstract: Based on fuzzy control theory and algorithms, the speed control of fluid coupling was presented. According to variable speed principles and methods, the system of fuzzy variable speed controller was introduced; fuzzy control models were established for fluid coupling. Variable speed process was controlled intelligently by computer. Parameter adjustment was fixed, deviation value was determined and input and output scale factors were modified based on service conditions. The target was approximated by successively reducing the control range.

Abstract: The cycle function of input flow rate was obtained by Fourier transformation of the instantaneous input flow rate of external mesh gear pump. The model of hydraulic system consisting of gear pump, spring, piston and load was established, the differential functions of the model were established too. The influence of dynamic compensating characteristics in the system caused by both pistons with different area and stiffness of spring was analyzed with MATLAB software and the change of fluctuating flow in the same system was obtained. The simulation result shows that the flow fluctuation of external mesh gear pump could be reduced by using the spring-piston system.

Abstract: The paper discusses the performance of a hydraulic system controlling the shifting action of a construction vehicle transmission. Based on the principle of the hydraulic system of the transmission, a simulation model of the hydraulic system is established using AMEsim software. The simulation results indicate that the double-step hydraulic cylinder structure has an advantage of a fast, smooth and reliable shifting. The shifting connecting and separating overlap time of two clutches can be controlled precisely by an electronic joystick. The fast response speed can be ensured because using screw-in cartridge valves acting as the directional valves. Some techniques of improving the shifting quality are obtained. There is a great reference for the construction vehicles’ transmission in the future.

Abstract: For the problem of gas accumulation in upper corner of "U" type ventilation system mining face, a new approach to eliminating gas accumulation in upper corner of coal mining face by using high-speed rotating jet is proposed based on flow law of rotary jet and actual environment of coal mining face. The numerical simulation with Fluent software is carried out. The results show that when fan is mounted close to the wall, the high-speed rotating jet has good Coanda effect, little impact on air flow structure of coal mining face, and is significantly effective to deal with gas accumulation in upper corner. FLUENT based numerical simulation provides a theoretical basis for actual application of rotary jet fan in coal mining face.This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: Pneumatic Presses are marked by features of high-motion speed, high productivity, energy conservation and environmental protection. The drawback is its low air system pressure, generally only 0.4-0.7 MPa, which unsuited to occasion require large output force. A new pneumatic press, based on quadratic orthogonal toggle force amplifier, is introduced in this paper. The output force of pneumatic piston is amplified for two times and force amplifying ratio can up to 20, thus to increase the output force substantially, although with constant piston diameter and system pressure. Moreover, with the application of symmetrical double-face rack-gear mechanism, radial force on piston rod and lateral force on pressure head are perfectly balanced. The entire mechanical system boasts features of low friction loss, low vibration and noise and high transmission efficiency.

Abstract: Two-point floating clamping device, widely used in manufacturing field, can effectively ensure the same clamping force on different workpieces or different surfaces in one workpiece. But due to the application of unitary suspended articulated cylinder, traditional two-point floating devices have disadvantages such as poor working status, great impaction, vibration and noise. A kind of innovatively designed two-point floating clamping devices, with rigidly fixed cylinder replacing unitary suspended articulated cylinder, is presented in this paper. To solve the problem of insufficient degrees of freedom, three different methods are applied. This device has significant advantages in compact structure, small impaction and vibration noise. Moreover, the working principle and mechanical calculation formulas are presented in this paper, which is instructive to the industrial field.