DETERMINATION OF THE RATIONAL LENGTH OF THE BLOCK ALONG THE STRIKE FOR EXPANSION TO PROVIDE SAFETY AND EFFICIENCY IN THE WORKING OF THE MEDIUM THICK IN-CLINED COAL SEAMS WITH THE ROOM AND PILLAR SYSTEM IN THE QUANG NINH COAL BASIN

An analysis of the constraints that apply the technology and the complexities of the mining and geological conditions of the Quang Ninh coal basin. The possi-bility and expediency of using the foreign experience of working out of the me-dium thick inclined coal seams in the mines of Vietnam. The scheme of prepara-tion and working out of the excavation area is given in view of the technological features in difficult mining and geological conditions, using the room and pillar system and determination of the rational length of the block along the strike.

Justification of Spatially-Planned Solutions and Determination of the Dimension Block in the Working of the Medium Thick Inclined Coal Seams with the Room and Pillar System

Technological parameters for working out of the medium thick inclined coal seams with a diagonal arrangement of a line of a working face. An analysis of the constraints that apply the technology and the complexities of the mining and geological conditions of the Quang Ninh coal basin. The possibility and expediency of using the foreign experience of working out of the medium thick inclined coal seams in the mines of Vietnam and justification of spatially-planned solutions for working. The scheme of preparation and working out of the excavation area is given in view of the technological features in difficult mining and geological conditions, using the room and pillar system and determination of the rational length of the block along the strike.

Study on Selection of the Length of Reinforced Concrete Segment for Oil and Gas Shield Tunnel with 3D Numerical Analysis

3D finite element analysis is utilized to calculate stress and internal forces in three different lengths of reinforced concrete segment for oil and gas shield tunnel subject to water and earth pressure by means of load-structure model. The rational length of concrete segment is determined to be 1.2m long after comparing the calculated stress and internal force in concrete segment with length of 1.0m, 1.2m and 1.5m respectively. Meanwhile, the safety factor is also compared in order to determine the rational length of concrete segment. The analysis shows that segment length for oil and gas shield tunnel with small cross-section should be less than 1.2m so as to facilitate its transportation and erection on construction site.

Analysis on the Workspace of a Tomato Harvesting Manipulator with 7 DOF

This work presents a workspace solving approach for a tomato harvesting manipulator with seven degrees of freedom (7 DOF) based on a special envelope method. In this method, the joints of the manipulator was categoried into two groups, and the workspace boundary of each group was formulated according to the envelope equation by MATLAB and AutoCAD by considering the joint limits. To analyze the reachable and dexterous workspace, the position and orientation of the last link was plotted. The results show that the width and height of the wrist workspace of the tomato harvesting manipulator are 1.5 and 1.2m respectively, which can satisfy the tomato picking requirements. The reachable workspace and the dexterous workspace are affected by the length of the last link and the end-effector. In order to minimize the hollow in the workspace, it is necessary to choose the rational length of the 5th link and the 3rd link and the angle range of the 5th joint. The algorithm can make the workspace visualized and be applicable to all practical manipulator configurations.