Applied Mechanics and Materials Vols. 170-173

Abstract: The RNG k-e model and dynamic mesh technology are applied to simulate the unsteady flow of flaring gate pier and stilling pool during the process of radial gate opening. The space-time change law of hydraulic characteristics is obtained. The negative pressure exists on weir surface while the relative opening degree (e) is less than 0.3; the maximum pressure on the slab of stilling pool increases and moves to downstream with the gate opening; the velocity near the slab is relatively larger in the foreside of stilling pool and reaches the maximum value at e=0.5. The numerical results agree well with the experimental data, which shows the method is effective and can provide reference for shape optimization of practical engineering.

Abstract: A method for orthogonal grid generation is presented. The generating system is based on solution of a system of partial differential equations with finite difference discretization. The influence of the number of grid points, type of boundary, and intensity of the grid quality control function and grid properties are investigated. Specification of both boundary point distribution on all sides is used. The proposed method is applied to various test problems，which shows this method provides a good balance between controlling grid orthogonality and cell aspect ratio.

Abstract: The vehicle routing planning in the process of logistics is a hot issue. There is a lack of traditional genetic algorithm used to solve this issue, so the taboos is introduced to improve it. The improved genetic algorithm based on taboos get high-search speed compared to the traditional genetic algorithm, and this improvement is verified by the example.

Abstract: The author, based on the rock mass’ 3D modeling and solid graphics cutting method, advances a from-whole-to-part and from-part-to-whole rock cutting technology, which takes the rock faults and joint fissure of the original rock graphics as the geometric boundary, and takes the rock material division as mechanical control boundary. Being a carrier of grid, each basic rock’s geometry characteristics, topological relations (angle, edge, face, body, etc) and mechanical characteristics (e、μ、c、φ、κ, etc.) are all attached to the rock mass’s graphics. The relationship networks of every block are also stored. Such a collection of orderly and related graphical blocks provides the most basic and general database for all kinds of numerical calculations in geotechnical engineering. It can conveniently generate grid system according to different calculating requirements. After being exercised and examined in several projects, it is proved to have a good application prospect.

Abstract: This paper proposed hydraulic support longwall method for mining glacis thin orebody. The DaZhuang ore section of Guandian Ore Mining whose orebody in the line of -8＇—-16＇was chosen as the research object. It applied the FLAC numerical simulation method to study the changes of surrounding rock stress in the mining face, displacement and plastic zones, and put forward the changing law of the rock stress, displacement and plastic zones in the mining process. Besides, it proved that the mechanical condition of the roofs changed in different stages. When the distance between pillar and mining face was in the range of 4m—8m, the state was relatively stable, and the pillar and surrounding rocks were in small range of shearing and tensile yield. When distance was 12m, the roof suffered from compression. When it was up to 16m, the roof and bottom rock displayed tension. However，the appreciation of stress changed very little at different stages. The stress concentration circle formed between the top and bottom of the pillar, and the unloading appeared in the top and bottom gap. The nearer to the coal face, the more powerful of stress concentration, and the influence of pillar’s position on stress concentration degree is very little in the front of coal face. The structure would be in stable equilibrium when the distance between single stent and coal face is 12m. In such circumstances, the security of roof would be improved if more stents are added

Abstract: Text classification is the task of assigning natural language textual documents to predefined categories based on their context. The main concern is this paper is to improve the accuracy of text classification system combined an improved CHI method and semantic similarity metric. Firstly, use an improved CHI method to select features from the raw features aim to reduce the dimensions of the features. Secondly, calculates the semantic distance between text feature vector and categorization feature vector so as to determine the document categorization. Finally, we carried out a series of experiments compared with other methods using the F1-measure. Experimental results show that our new method makes an important improvement in all categories.

Abstract: In order to understand more clearly the law of groundwater seepage, recharge, excretion and dynamic change of groundwater level in the Horse River of Xishimen Iron Mine, it makes full use of MIDAS/GTS to build seepage model of settlement zone in Horse River, and by the analysis of changes of total head and the pore water pressure of the model ,we can study Horse River seepage law in the influence of mining , and track and survey the actual project. The results show that, the finite element model with the actual engineering seepage water head, pore pressure are compared, so as to provide the basis for the selection of Horse River seepage reinforcement scheme.

Abstract: In order to realize high precision position tracking control in some dc servo system, aimed at all kinds of uncertainties, a disturbance torque compensation control tactics is put forward. In other words, friction model is approximated online by fuzzy system and identification result is taken as compensation item of control algorithm. Besides, adaptive fuzzy compensation PID algorithm is utilized. Simulation results show that compared with conventinal PID control, this control tactics can enhance dynamic performances and steady-state precision, satisfying performance requests.