To fully exploit the coal resource under building,and to ease the conflict of exploitation and mining,so as to prolong service time of the mine and reduce the damage to the building caused by mining activity under building to its minimum,the mining scheme is studied.Referring to the geological and mining condition of Wujiachong mine Xinsheng colliery in Hunan,the relation between mining order and displacement and deformation of ground surface is simulated,the result of numerical simulation shows that the maximum values of various parameters of building surface movement and distortion during succesive mining is bigger than those for jump mining.
The university idea is the one that reflects the nature and law of university and directs the development of university. The classic university idea raised by Humboldt in the 19th century is the reflection of internal logic of the university development and its position and function in social life. With the pluralism of the contemporary higher education development, the connotation of the classic university idea will change correspondingly. On the basis of analyzing the background of the classic university idea, the paper will pay close attention to the change of the classic university idea connotation in present age, and try to provide some reference for people to understand the contemporary university idea properly.
Abstract To study the bond performance between fiber-reinforced seawater sea-sand concrete and corrosion-resistant rebars (glass fiber–reinforced polymer [GFRP] bars and epoxy resin–coated rebars) in extremely hot and humid marine environments, bond anchorage tests between reinforcement and seawater sea-sand concrete are conducted to study bond performance. The failure morphology of reinforced concrete was investigated, and the bond-slip curves of different types of rebar and concrete were compared. According to the research results, the addition of basalt and polypropylene fibers to seawater sea-sand concrete changed the distribution of bonding stress, which was conducive to an improvement in the anchorage efficiency of reinforcement and concrete. The chemical bonding performance between the fiber-reinforced seawater sea-sand concrete and rebar is improved, wherein the bond stress increases by 94.01 % at the beginning of the slip, and the residual bond stress increases by 91.72 %. Compared with ordinary seawater sea-sand concrete, the bonding strength between ordinary reinforced rebar and fiber-reinforced seawater sea-sand concrete increased by 20.75 %, and the bonding strength between the GFRP bar and fiber-reinforced concrete decreased by 15.37 %. Based on the friction mechanism of rebars and concrete, bonding strength models of ordinary rebar, epoxy resin–coated rebar, and GFRP bars with fiber-reinforced seawater sea-sand concrete are presented.
This study mainly introduces the advanced A* algorithm and steepest descent method for path planning based on grid form. A* algorithm is a node-searching strategy, namely uses the heuristic function to estimate the cost of the path from the start to the goal in the grid maps. The branching factor of A* algorithm describes the moving directions, which will be selected according to the path length in different grid maps. The steepest descent method adopts a heuristic-based gradient method with grid maps to search the shortest path. In this paper the appropriate path planning method will be selected by comparing the run time and the creation of complex maps of the two methods.
The trajectory-tracking problem for mobile robots is considered. A finite-time tracking control algorithm based on variable structure is proposed. Two designed control laws are constructed to stabilize steering angle error and position errors in finite time based on state feedbacks. Involving in results about finite-time stability, we prove that the desired trajectory is attained fully in finite time with the two control laws. Numerical simulations show the effectiveness of the control laws.
In order to study the fault diagnosis method of small underwater thruster, an experimental device for fault diagnosis of underwater thruster is designed, and a controller hardware and monitoring software of upper computer and lower computer are developed to realize the acquisition and storage of parameters for underwater propeller. The experimental device can simulate four kinds of thruster faults, collect the hydrophone data, classify the fault types by fault clustering analysis, analyze the spectrum of four types of faults, and calculate the thrust under different fault conditions based on the results of spectrum analysis. The experimental results show that the experimental system effectively simulates different faults of the thruster, and the analysis method realizes the classification of different faults. The thrust loss of different faults is also calculated based on the analysis method.
The methods from culturology can be applied to the interpretation of The Book of Songs. The paper, using the methods of culturology, is to analyze the famous July from The Book of Songs and settle some disputable issues as 1) defining the season indicated in the verse of the time of the first run, the time of the second run … and the bird ‘ju’ sings in July, based on the ancient calendar, 2) interpreting the meaning of Nanmu, based on the ancient agricultural hydraulic system, and 3) explaining why July shares simultaneously the styles of folk music, capital music as well as court music with the knowledge from the ancient music history.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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