Advanced Materials Research Vols. 468-471

Abstract: The numerical model of top coal drawing in gently inclined seam is built based on PFC2d software. By comparing with the theory of drawn-body movement law, it can be obtained that the shape of top coal drawn-body accords with the theory of random medium movement. The research results show that the form of the shape equation of top coal drawn-body is uniform while the top coal caving angle is different. On the other hand, with the difference of top coal caving angle and drawing height, the shape of top coal drawn-body is differential at the meso scale, which depends on the parameters of the shape equation of top coal drawn-body.

Abstract: The full flow field model of a widely used multi-blade centrifugal was built, using the CFD method, the steady and unsteady numerical simulation of the inner flow in the fan at different working conditions are presented. The numerical simulation results were validated by contrasting to the experiment results. The results displayed the characteristics of the velocity field, pressure field and pressure fluctuate in the centrifugal fan. The results can provide basis for optimizing the fan design and the internal flow, and have important value of engineering applications in the increase of the overall performance in operation.

Abstract: For developing free-piston diesel engine, The two stroke Reverse-Loop scavenging diesel engine E150 was taken as the prototype and a simplified model was built by using CATIA software. Based on the influence of different factors about the gas exchange process，several layouts of scavenging air belt to be built in different schemes. Then the influence of the main structure parameters of scavenging air belt to the gas exchange process were analyzed and a better scheme of structural parameters was obtained.

Abstract: In this paper, we consider the non-oscillatory problems of linear delay differential systems of odd-dimension. Based upon the corresponding characteristic equations, we get some criteria for non-oscillation by utilizing the matrix measures.

Abstract: The paper deals with the investigation of 3D digitizing of small parts specifically by optical 3D scanner GOM ATOS TripleScan. The paper shortly illustrates the general concept of Reverse Engineering, which includes also the 3D scanning. The paper also describes the optical 3D scanner GOM ATOS TripleScan and a three-dimensional model obtaining procedure by means of this scanner. In the main part of the paper the concrete 3D scanning process of chosen individual objects is described (clips, ball nose end mill, screw drill, coin). Their shape and size were specific and distinct, therefore it was possible to test and compare particular digitizing attributes. The problems that occurred during 3D digitizing of individual parts are step by step discussed and solved.

Abstract: To evaluate an influence of the various bend diameter ratio R_c/R and velocity on the flow property of gel propellant in a 90⁰ pipe bend, the 3D governing equations of the steady, incompressible, isothermal, laminar flow of a power-law, shear-thinning gel propellant in pipe bend were formulated, discretized and solved, a SIMPLEC numerical algorithm was applied for the solution of the flow field, which on a series of sharp 90⁰ curved pipelines with nine kinds of bend diameter ratio and the inner diameters of 8mm were used on condition of seven kinds of Reynolds numbers. The pressure and velocity distributions were obtained, the empirical equation of local resistance coefficient from numerical experiments was conducted, providing the interrelations between the best bend diameter ratio and flow velocity in engineering design. The results indicate that the pressure and velocity distributions were non-linear, and which become tremendous with increasing Reynolds numbers. The results suggest that the dot of maximum velocity occurs the wall outside of a pipe bend, and which is more near to the wall outside of a pipe bend along the flowing direction and increasing the velocity. The phenomena of particle sedimentation should be took into account to investigate the flowing behavior of gel propellant in curved pipes on condition of lower Reynolds numbers.

Abstract: The round raster is extensively applied in all kinds of high accuracy angular displacement measurement and control system.With the development of precise mechanotronics measuring instrument, machining center, CNC machine and various precise location testing technology, a higher request is put forward to the accuracy and the function of raster measurement system. In this article it is concluded that double readheads is the most reasonable configuration scheme through tests of single readhead scheme,two readheads and four readheads.

Abstract: We research the super two-stage rapid drill of shaft well boring machine, taking the mathematical model of the drill in the stress field of shaft bottom as theoretical basis. Taking linear elastic and nonlinear features of element material into consideration, we establish element model in the stress field of shaft bottom and material model of stratum rock. Furthermore, we use the finite element method to numerically simulate the fragment intake effect of the super drills with diameter of 400mm and 800mm respectively. The result can be applied in the field of mine exploiting and tunnel advancement.

Abstract: [Purpose] To explore the network publishing formed by the combination of the network and the traditional publishing industry, the rapid development of new media and its effect on the editorial activities. [Process and method] Adopting the combining of empirical analysis with normative analysis, system analysis with statistical analysis, and actual investigation with literature research.[Results] To demonstrate the concept and connotation of network publishing, to discuss rich and colorful, blending, invariance properties of editing activities under the environment of network publishing, from the collection of information, research, planning, organizing, peer review, editing, proofreading to graphic design and other aspects, which has effect of the network publishing on editorial activities. [Conclusions] Network and multimedia technology promotes the development of editing industry, has profound effect on editing activities and challenges the editing staff.

Abstract: To solve the problem of acoustic source localization in wireless sensor networks (WSN) under interference of environmental noise, a novel acoustic source localization method in WSN based on Least Square Support Vector Regression (LSSVR) modeling (ASL-LRM) was proposed. The ideal measured values of acoustic sensors were used to compose feature vector at first. Then LSSVR models were built by LSSVR modeling on the mapping relation between feature vector and acoustic source coordinate. The acoustic source was then located by inputting feature vector composed of real measured values of the sensors into LSSVR models. The modeling parameters optimization method based on localization effect in sample locations was also discussed. Experiments were performed in 100 test locations. RMSE values by ASL-LRM method in 72-76 test locations were less than MLE method and reduced by 60%-74% at most. In lower signal-to-noise ratio case, there were 87 test locations where RMSE values by ASL-LRM method were less than 2 meters, while there were only 12 test locations by MLE method. It shows ASL-LRM method achieves better localization effects in a large part of the region surrounded by sensor nodes. It especially has advantage on the occasions like lower signal-to-noise ratio or high precision localization.