Advanced Materials Research Vols. 418-420

Abstract: In order to reduce the aerodynamic drag, a domestic car was selected as study object to research the size and the layout of the vortex generator with the method numerical stimulation. By comparing the values of drag coefficient (C_d) the cars with vortex generators (VGs) and the original and then analyzing the mechanism of drag reduction, a final optimized strategy was achieved. It was concluded that VGs can lower the C_d of a car but the effect depends on the size and the layout. Our research achievements can serve as reference for automobile aerodynamic drag reduction, and are also significant to energy saving and emission reduction.

Abstract: A new algorithm based on local gradient is proposed to inspect steel rod surface defects. The local gradient method can weaken the effect of noise in steel rod surface image. Then the open operation of morphology theory is employed to remove the retaining noise. Experiments show that this algorithm is effective to inspect steel rod surface defects and is time-saving.

Abstract: Current status of the direct spinning production lines in high unit capacity of the polyester textile fibers in China are investigated, as well as the status and development of flexible production technique.

Abstract: Chattering elimination of machining processes is an important issue in turning operation, due to the damages caused by this phenomenon. Limited productivity rate, decrease in tool life, poor surface quality and noisy workplace are some adverse effects of the chatter vibration. In this paper two control strategies are developed to suppress chatter vibration in turning process including a worn tool. A single degree of freedom model of the turning process including tool wear is briefly described. In the first stage, sliding mode approach used to control the system, and in the second stage fuzzy sliding mode approach is used. The simulation results indicate that the fuzzy sliding mode performs better than the direct sliding mode controller.

Abstract: The CAD system for three-plate parallel cam indexing is developed by means of Pro/toolkit and Visual C++ 6.0. The main idea is to encapsulate the whole design process into the system. Users simply enter the geometric parameters and motional parameters of three-plate parallel indexing cam into the interface and can obtain the graphs of the parallel indexing cam and other parts in required size. The system can offer a fast, accurate and dynamic design, and shorten the product design and reduce the production costs.

Abstract: Cutting mechanism and characteristics of difficult-to-cut materials have a great difference. Currently, systems or indicators of the machinability are so many that we do not know how to utilize them. Not only because there is no consideration the impact of cutting conditions and parameters on machinability, but they are not be accurate quantitative responses to the machinability of workpiece materials, especially to the difficult-to-cut materials. Based on in-depth analysis of cutting mechanism and objective functions of cutting parameters optimization, an innovative machinability evaluation system based on the variable processing cost per unit material is developed. And the economics of machining process are introduced to the machinability evaluation system. Several classic analysises and calculation examples of the machinability of several typical difficult-to-cut materials have been presented at the end of paper to give a clear picture from the application of the system. The result demonstrates that the machinability evaluation system based on the variable processing cost per unit material has good practicability and maneuverability.

Abstract: Aiming at small power grid’s influencing on the frequency stabilization of the power grid when load’s large change, the basic development present situation and work principle of active power filter are analyzed at first. Then combining active filter’s control strategy based on instantaneous reactive power and hysteresis current, the active filter simulation model about grid frequency’s change is established according to studying the method of using adaptive notch filter to measure power frequency. Finally, the simulation results prove that the active power filter model could track the changing frequency quickly and compensate harmonic current accurately, and enhance power quality and reliability of the small power grid.

Abstract: Polymer materials, such as PMMA and PDMS, have been of great interest in the research and development of MEMS recently due to their relatively low cost and easy process. In this research, we are trying to fabricate Ni Micro needle array from PMMA master by through PDMS mold based on multi-mold transformation technology. The fabricated micro nickel needles array is 900 microneedles in 1 cm2 chip area and the height of each needle is about 150um.

Abstract: Rough set theory is an efficient mathematical theory for data reduction and knowledge discovery of various fields. However, classical rough set theory is not applicable for knowledge induction of incomplete information systems. In this paper, a concept of interval granule is presented. Based on this concept, the hierachical structure of knowledge granularity and approximation of rough sets in incomplete information systems are studied, and related properties are given. An example show that the interval granule have better results than existing models for knowledge induction and approximation.

Abstract: Abstract For complex and difficult geology, it is difficult to design right cutters for TBM in the conventional ways. So the successful experiences and data accumulated are very useful in TBM disc cutters design. CBR is a reasoning methodology that exploits similar experienced solutions, in the form of past cases, to solve new problems. This paper proposes an AHP-Based CBR model that overcomes the difficulty of measuring experience for determining the relative weight of attributes by the analytic hierarchy process. By comparing, the model using the analytic hierarchy process was more accurate, reliable, and explanatory for solving new problems using experience from previous cases.