Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, th...Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, this study put forward powerful anchor support system and anchor cable adaption technology to surrounding rock deformation. Furthermore, the control measures possess the supporting performance with ‘‘primary rigid-following flexible-new rigid, and primary resistance-following yield-new resistance'', which suits deep roadway surrounding rock control. The mechanical model of truss anchor supporting roof beams was established, and the inverted arch deflection produced by the cable pre-stress with stress increment effect and roof beam deflection were obtained. And then the system working mechanism was illustrated. Finally, the surrounding rock support parameters were determined by means of comprehensive methods, and put into practice. The results show that surrounding rock deformation realized secondary stability after three months. The roadway sides convergence value was less than 245mm, and roof subsidence was less than 124mm. In addition, there was no expansion and renovation during service period.展开更多
Considering the actual demand for high-speed operation of induction motors in industrial occasions,the characteristics of induction motors in different regions are analyzed,especially the field weakening characteristi...Considering the actual demand for high-speed operation of induction motors in industrial occasions,the characteristics of induction motors in different regions are analyzed,especially the field weakening characteristics of induction motors in high-speed operation are studied.A field weakening control method of induction motor based on model predictive control(MPC)algorithm is proposed,which can predict the future state of the controlled object,and then obtain the optimal control variables by colling optimization.The simulation results show that the field-weakening control method based on MPC algorithm has faster response speed,stronger robustness and better control performance than the traditional control methods.展开更多
Failure detection module is one of important components in fault-tolerant distributed systems,especially cloud platform.However,to achieve fast and accurate detection of failure becomes more and more difficult especia...Failure detection module is one of important components in fault-tolerant distributed systems,especially cloud platform.However,to achieve fast and accurate detection of failure becomes more and more difficult especially when network and other resources' status keep changing.This study presented an efficient adaptive failure detection mechanism based on volterra series,which can use a small amount of data for predicting.The mechanism uses a volterra filter for time series prediction and a decision tree for decision making.Major contributions are applying volterra filter in cloud failure prediction,and introducing a user factor for different QoS requirements in different modules and levels of IaaS.Detailed implementation is proposed,and an evaluation is performed in Beijing and Guangzhou experiment environment.展开更多
Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt,...Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt, which represented the effect of a bolt on the surrounding rock in roadways in order to obtain its elastic solution. Simultaneously, we analyzed factors affecting the axial compression of the bolt on the surrounding rock and obtained the axial stress contours of the anchorage area through this elastic solution. The results indicate that 1) the axial compression stress in the anchorage area is proportional to the pre-tightening force and confirms the rule that stress declines sharply with the increase in axial distance from the bolt, with an effective stress radius of 1 m; 2) the maximum axial compression stress declines first and then rises with the increase in depth from the surface of the anchorage surrounding rock and 3) the size of the axial compression area is mainly determined by the length of the bolt.展开更多
In order to improve the source water quality of drinking water and mitigate the load of drinking water treatment plant, a pilot test was conducted with integrated horizontal flow constructed wetlands to pretreat the w...In order to improve the source water quality of drinking water and mitigate the load of drinking water treatment plant, a pilot test was conducted with integrated horizontal flow constructed wetlands to pretreat the water supply in the reservoirs of Yellow River. Resuhs show that under the hydraulic loading rate of 4 m^3/（ m^2 · d）, the average removal rates of chemical oxygen demand （COD）, total nitrogen （TN）, ammonium nitrogen （ NH4 ^＋ - N）, nitrate nitrogen （ NO3 ^- - N）, nitrite - nitrogen （ NO2^ - - N） and total phosphorus （TP） in the horizontal flow constructed wetlands are 49. 68% , 53.01%, 48.48%, 53.61% , 62. 57% and 49. 56%, re- spectively. The study on purifying mechanism of the constructed wetlands indicates that the disposal of contamination by subsurface wetlands is the combined actions of physical chemistry, plants and microorganism.展开更多
The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring spee...The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.展开更多
基金provided by the National Natural Science Foundation of China(No.51234005)National Basic Research Program of China under Grant(No.2010CB226802)Fundamental Research Funds for the Central Universities(No.2010QZ06)
文摘Aiming at the surrounding rock control problem of mining and preparation entries in Xingdong mine with large mining depth, and the comprehensive control countermeasures including high pre-stress cable truss system, this study put forward powerful anchor support system and anchor cable adaption technology to surrounding rock deformation. Furthermore, the control measures possess the supporting performance with ‘‘primary rigid-following flexible-new rigid, and primary resistance-following yield-new resistance'', which suits deep roadway surrounding rock control. The mechanical model of truss anchor supporting roof beams was established, and the inverted arch deflection produced by the cable pre-stress with stress increment effect and roof beam deflection were obtained. And then the system working mechanism was illustrated. Finally, the surrounding rock support parameters were determined by means of comprehensive methods, and put into practice. The results show that surrounding rock deformation realized secondary stability after three months. The roadway sides convergence value was less than 245mm, and roof subsidence was less than 124mm. In addition, there was no expansion and renovation during service period.
基金National Natural Science Foundation of China(No.61663022)Changjiang Scholars and Innovaton Team Develpment Plan(No.Rt_16R36)。
文摘Considering the actual demand for high-speed operation of induction motors in industrial occasions,the characteristics of induction motors in different regions are analyzed,especially the field weakening characteristics of induction motors in high-speed operation are studied.A field weakening control method of induction motor based on model predictive control(MPC)algorithm is proposed,which can predict the future state of the controlled object,and then obtain the optimal control variables by colling optimization.The simulation results show that the field-weakening control method based on MPC algorithm has faster response speed,stronger robustness and better control performance than the traditional control methods.
基金supported by the National High-tech Research and Development Program(863) of China under Grant No. 2011AA01A102
文摘Failure detection module is one of important components in fault-tolerant distributed systems,especially cloud platform.However,to achieve fast and accurate detection of failure becomes more and more difficult especially when network and other resources' status keep changing.This study presented an efficient adaptive failure detection mechanism based on volterra series,which can use a small amount of data for predicting.The mechanism uses a volterra filter for time series prediction and a decision tree for decision making.Major contributions are applying volterra filter in cloud failure prediction,and introducing a user factor for different QoS requirements in different modules and levels of IaaS.Detailed implementation is proposed,and an evaluation is performed in Beijing and Guangzhou experiment environment.
基金Projects are the National Basic Research Program of China (No.2007CB209400)the 111 Project (No.B07028)the National Natural Science Foundation of China (Nos.50634050 and 50904065)
文摘Axial compression stress, produced by the pre-tightening force of a bolt, is a necessary condition for surrounding rock to form a whole structure. For this study, we built a mechanical model for an end-anchorage bolt, which represented the effect of a bolt on the surrounding rock in roadways in order to obtain its elastic solution. Simultaneously, we analyzed factors affecting the axial compression of the bolt on the surrounding rock and obtained the axial stress contours of the anchorage area through this elastic solution. The results indicate that 1) the axial compression stress in the anchorage area is proportional to the pre-tightening force and confirms the rule that stress declines sharply with the increase in axial distance from the bolt, with an effective stress radius of 1 m; 2) the maximum axial compression stress declines first and then rises with the increase in depth from the surface of the anchorage surrounding rock and 3) the size of the axial compression area is mainly determined by the length of the bolt.
基金Sponsored by the National High Technology Research and Development Program (863) of China (Grant No.2006AA06Z303)the National Natural Sci-ence Foundation of China(Grant No.40671004)the Program for Young Academic Backbone of Harbin Normal University(Grant No.KGB200821)
文摘In order to improve the source water quality of drinking water and mitigate the load of drinking water treatment plant, a pilot test was conducted with integrated horizontal flow constructed wetlands to pretreat the water supply in the reservoirs of Yellow River. Resuhs show that under the hydraulic loading rate of 4 m^3/（ m^2 · d）, the average removal rates of chemical oxygen demand （COD）, total nitrogen （TN）, ammonium nitrogen （ NH4 ^＋ - N）, nitrate nitrogen （ NO3 ^- - N）, nitrite - nitrogen （ NO2^ - - N） and total phosphorus （TP） in the horizontal flow constructed wetlands are 49. 68% , 53.01%, 48.48%, 53.61% , 62. 57% and 49. 56%, re- spectively. The study on purifying mechanism of the constructed wetlands indicates that the disposal of contamination by subsurface wetlands is the combined actions of physical chemistry, plants and microorganism.
文摘The dissolution kinetics and mechanisms of reaction of Batagbon Kaolin in sulphuric and fluosilicic acids were studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It is observed that the dissolution rate increases with decreasing particle size and solid-to-liquid ratio, and increases with stirring speed, acid concentration, and leaching temperature. The experimental results indicate that the dissolution rate is of mixed control via hydrogen ion [H＋] action, with reaction order of 0.813 and the reaction kinetics can be expressed as gmt=[1-（1-x）l/3＋y/6[（l-x）l/3＋ 1-2（1-x）2/3]. The activation energy of the process is determined to be 21.6 k J/mol. The level of the product quality is also evaluated.
