Key Engineering Materials Vols. 467-469

Abstract: In nondestructive testing, in order to avoid the processing waste and repair the defects, the accurate location of the inner defects of components has been used to determine the danger of defects, which is very helpful to eliminate the workpiece as soon as possible. In the paper, the theory of binocular vision has been successfully applied to locate the inner defects accurately in the nondestructive testing field. Firstly, a simple and effective mathematical model has been built. Secondly, the simulation method has been used to verify the model. At last, the error theory has been applied to analyze the error, which would have effect on the test result. The most direct and effective method with high precision has also been proposed. It has been proved that the method has high precision and great simplicity to design. Through the X-ray image, the method could also been used to locate the depth information of the inner defects in metal casting, which would provide a good solution to the DR and CT deficiency.

Abstract: With the development of Internet, web page is still the main form of network information transmission. The number of web pages is growing at the rate of 10 million a day, and also the complexity of web information itself, which all make it difficult for the theme search engines to search information rapidly and accurately. Therefore, higher requirements are put forward to web information extraction. In this paper, a DOM-based multi-factor web information extract Algorithm (DMWE) is proposed, which can extract theme information rapidly and accurately.

Abstract: The characters of the Manufacturing Process Information System (MPIS) for industry-oriented are included here. The characters of the process and the difficulty faced for cable industry are summarized. Then, A model structure of MPIS for cable industry is established. A method based on Rough Set Theory for processing plan knowledge system is put forward. An example for processing knowledge finding is studied at last.

Abstract: As a special hot-work progress, artillery shooting test was put in practice, and rotating band specimen of Cu-4 Mass%Zn alloy was prepared. The mesostructure and microstructure evolution of the alloy under instantaneous extrusion and high speed friction were observed by optical microscopy (OM) and scanning electron microscopy (SEM). Severe plastic deformation (SPD) and dynamic recrystallization phenomena were researched. The analysis results are as follows. At the beginning of SPD, under the instantaneous compression, the surface layer of alloy became fibrous tissue with the phenomena of work-hardening. With the plastic deformation continue, temperature of alloy arising rapidly under the high speed friction. Recrystallization occurs within the outermost part of fibrous tissue due to heating, so subgrains gradually become homogeneous equiaxed grains. In addition, SPD has little effect on the inner tissue, which is full of equiaxed grains still. Between equiaxed grains and fibrous tissue, there are many oblique strip grains which formed by radial extrusion stress , tangential slip stress and axial sliding stress .

Abstract: Single-pipe ring-type mixing water oil-gathering process is often used in the oil-gas gathering and transportation system of low permeability oilfield. In order to improve the economic benefits of exploitation and construction of low permeability oilfield, multi-objective parameters optimization mathematical model of single-pipe ring-type mixing water oil-gathering process is built with the targets of minimization of pipeline construction investment, thermal energy and power energy consumption. The model belongs to the mixed-discrete variable nonlinear optimization problem. According to the structure characteristics of the model, multi-objective parameters optimization mathematical model is changed into the single-objective optimization by using linear weighting method. Then the single-objective optimization is solved by hybrid genetic algorithm. Network optimized design of a block of oil-gas gathering and transportation system is conducted by the model mentioned in this paper, and the result is that pipeline construction investment reduces 12.4 percent, thermal energy consumption reduces 14.4 percent and power energy consumption reduces 12.4 percent.

Abstract: Working memory is one of important cognitive functions and recent studies demonstrate that prefrontal cortex plays an important role in working memory. But the issue that how neural activity encodes during working memory task is still a question that lies at the heart of cognitive neuroscience. The aim of this study is to investigate neural ensemble coding mechanism via average firing rate during working memory task. Neural population activity was measured simultaneously from multiple electrodes placed in prefrontal cortex while rats were performing a working memory task in Y-maze. Then the original data was filtered by a high-pass filtering, spike detection and spike sorting, spatio-temporal trains of neural population were ultimately obtained. Then, the average firing rates were computed in a selected window (500ms) with a moving step (125ms). The results showed that the average firing rate were higher during workinig memory task, along with obvious ensemble activity. Conclusion: The results indicate that the working memory information is encoded with neural ensemble activity.

Abstract: We have previously shown that microparts can be fed along an asymmetric microfabricated surface using simple planar symmetric vibrations. Microparts move forward because they adhere to the microfabricated surface asymmetrically. We have also described the effects of sawtoothed surfaces on the movement of submillimeter-sized microparts; for example, 0603 (size, 0.6 x 0.6 x 0.3 mm; weight, 0.3 mg) and 0402 (size, 0.4 x 0.2 x 0.2 mm; weight, 0.1 mg) capacitors. In the present work, we studied the effects of feeder materials on the feeding of single layer chip capacitors (size, 0.25 x 0.25 x 0.35 mm ; weight, 0.06 mg). We found that the motion of submillimeter microparts was affected not only by inertia but also by adhesion due to electrostatic, van der Waal's, and intermolecular forces, and to surface tension. These effects are dependent on the two materials that are in contact with each other. The four materials selected for feeder surfaces were microfabricated so that periodic sawtooth structures were present on their surfaces. We assessed micropart feeding using these surfaces, as well as the relationship between feeding velocity and vibration frequency. By comparing the feeding velocity on each feeder surface, we assessed the effects of feeder surface materials on the feeding of microparts.

Abstract: Product design is a repetitive iteration process. A small change may result in tremendous redesign changes. Considering the shortcomings of the variant design process, the paper presented an interpretive structural mode(ISM) to analyze product structure. The model not only visualizes the hierarchy of component modules within a product, but also reflects closeness and importance of components, offering a theoretical basis for variant design.

Abstract: Base on the consideration of knowledge share and knowledge complementarity, this paper establishes a dynamic knowledge alliance model. We analyze the effects of knowledge share and knowledge complementarity on equilibrium outcome, equilibrium profit and R＆D investments, and discuss the critical impact of knowledge complementarity on selection of alliance partner.

Abstract: This paper presents the modeling of a high-accuracy and high-acceleration table used for automatic wire bonder. The table is directly driven by linear voice coil motor (LVCM), and thus the mass and inertia of the motion system are significantly reduced by using a novel flexible decoupling mechanism based on flexure hinges and preloaded spring. The decoupling principle of the mechanism was introduced, and the electromechanical coupled mathematical model of Y-axis table was evaluated according to the dynamics of a mechanical mass-spring-damp system and LVCM. The model of Y-axis table was then identified with the aid of a Laser Interferometer and data acquirement card. Model validation experiments were carried out, and the results show that the model has sufficient accuracy when used to predict the performances of the real-world system under new conditions, and meanwhile it also can provide important information for the control of Y-axis table.