Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion...Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station.展开更多
The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling inst...The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling instability is not considered in the design codes. In this paper, the effect of web opening on both lateral torsional buckling and local buckling behaviors has been investigated. A simply supported steel I-beam has been studied under uniform bending moment around the major axis. Buckling analysis has been performed using the finite element method. Linear regression analysis has been conducted for output data to formulate an equation for the critical moment including web opening effect. The results have shown a limited reduction in the lateral torsional buckling capacity and a significant reduction in the local buckling capacity.展开更多
After the success of the Daya Bay experiment, the Jiangmen Underground Neutrino Observatory （JUNO） was launched to measure neutrino-mass hierarchy and oscillation parameters and to study other neutrino physics. Its ...After the success of the Daya Bay experiment, the Jiangmen Underground Neutrino Observatory （JUNO） was launched to measure neutrino-mass hierarchy and oscillation parameters and to study other neutrino physics. Its central detector is set for antineutrinos from reactors, the Earth, the atmosphere, and the Sun. The main requirements of the central detector are con- tainment of 20 kt of liquid scintillator, as the target mass, and 3% energy resolution. It is about a ball-shape detector of 38.5 m with -75% coverage of PMT on its inner surface. The design of such a huge detector is a big challenge because it must meet the requirements for several different types of physics measurement and possess the feasibility and reliability in its structure and engineering, all at reasonable time and cost. One option for the JUNO central detector is a hyper-scale acrylic ball sub- merged in the water to shield the background. This paper proposes a structural scheme for such an acrylic ball that is supported by a stainless-steel truss, inspired by point-supported glass-curtain walls in civil engineering. The preliminary design of the scheme is completed and verified by finite element （FE） method using ABAQUS. FE analysis shows that the scheme can con- trol the stress level of the acrylic ball within the limit of 5 to 10 MPa, in accordance with the demand of the design objective of the central detector. The scheme is of outstanding global stability and allows various chocces on local connections. We prove that the scheme is of good feasibility and should be a reasonable option for the central detector.展开更多
This paper studies the multi-objective optimization of space station short-term mission planning(STMP), which aims to obtain a mission-execution plan satisfying multiple planning demands. The planning needs to allocat...This paper studies the multi-objective optimization of space station short-term mission planning(STMP), which aims to obtain a mission-execution plan satisfying multiple planning demands. The planning needs to allocate the execution time effectively, schedule the on-board astronauts properly, and arrange the devices reasonably. The STMP concept models for problem definitions and descriptions are presented, and then an STMP multi-objective planning model is developed. To optimize the STMP problem, a Non-dominated Sorting Genetic Algorithm II(NSGA-II) is adopted and then improved by incorporating an iterative conflict-repair strategy based on domain knowledge. The proposed approach is demonstrated by using a test case with thirty-five missions, eighteen devices and three astronauts. The results show that the established STMP model is effective, and the improved NSGA-II can successfully obtain the multi-objective optimal plans satisfying all constraints considered. Moreover, through contrast tests on solving the STMP problem, the NSGA-II shows a very competitive performance with respect to the Strength Pareto Evolutionary Algorithm II(SPEA-II) and the Multi-objective Particle Swarm Optimization(MOPSO).展开更多
文摘Shearer and hydraulic support are matching equipments. To increase the operating speed of the shearer, the following speed of hydraulic support must be increased. This means increasing the volume of flow from emulsion power station. Analyzing the operating characteristics of hydraulic supports, the number of simultaneously operating supports is obtained by means of pressure parameter and time history at a certain time, which is a theory base for development of control system to multi-pump emulsion power station.
文摘The lateral torsional buckling phenomenon often governs design of steel I-beams. Although web opening is often used to accommodate the required mechanical and piping works in buildings, its effect on the buckling instability is not considered in the design codes. In this paper, the effect of web opening on both lateral torsional buckling and local buckling behaviors has been investigated. A simply supported steel I-beam has been studied under uniform bending moment around the major axis. Buckling analysis has been performed using the finite element method. Linear regression analysis has been conducted for output data to formulate an equation for the critical moment including web opening effect. The results have shown a limited reduction in the lateral torsional buckling capacity and a significant reduction in the local buckling capacity.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA10010200)the Tsinghua University Initiative Scientific Research Program(Grant No.20131089288)
文摘After the success of the Daya Bay experiment, the Jiangmen Underground Neutrino Observatory （JUNO） was launched to measure neutrino-mass hierarchy and oscillation parameters and to study other neutrino physics. Its central detector is set for antineutrinos from reactors, the Earth, the atmosphere, and the Sun. The main requirements of the central detector are con- tainment of 20 kt of liquid scintillator, as the target mass, and 3% energy resolution. It is about a ball-shape detector of 38.5 m with -75% coverage of PMT on its inner surface. The design of such a huge detector is a big challenge because it must meet the requirements for several different types of physics measurement and possess the feasibility and reliability in its structure and engineering, all at reasonable time and cost. One option for the JUNO central detector is a hyper-scale acrylic ball sub- merged in the water to shield the background. This paper proposes a structural scheme for such an acrylic ball that is supported by a stainless-steel truss, inspired by point-supported glass-curtain walls in civil engineering. The preliminary design of the scheme is completed and verified by finite element （FE） method using ABAQUS. FE analysis shows that the scheme can con- trol the stress level of the acrylic ball within the limit of 5 to 10 MPa, in accordance with the demand of the design objective of the central detector. The scheme is of outstanding global stability and allows various chocces on local connections. We prove that the scheme is of good feasibility and should be a reasonable option for the central detector.
基金supported by the National Natural Science Foundation of China(Grant No.11402295)the Science Project of National University of Defense Technology(Grant No.JC14-01-05)the Hunan Provincial Natural Science Foundation of China(Grant No.2015JJ3020)
文摘This paper studies the multi-objective optimization of space station short-term mission planning(STMP), which aims to obtain a mission-execution plan satisfying multiple planning demands. The planning needs to allocate the execution time effectively, schedule the on-board astronauts properly, and arrange the devices reasonably. The STMP concept models for problem definitions and descriptions are presented, and then an STMP multi-objective planning model is developed. To optimize the STMP problem, a Non-dominated Sorting Genetic Algorithm II(NSGA-II) is adopted and then improved by incorporating an iterative conflict-repair strategy based on domain knowledge. The proposed approach is demonstrated by using a test case with thirty-five missions, eighteen devices and three astronauts. The results show that the established STMP model is effective, and the improved NSGA-II can successfully obtain the multi-objective optimal plans satisfying all constraints considered. Moreover, through contrast tests on solving the STMP problem, the NSGA-II shows a very competitive performance with respect to the Strength Pareto Evolutionary Algorithm II(SPEA-II) and the Multi-objective Particle Swarm Optimization(MOPSO).
