Non-pillar mining technology with automatically formed roadway is a new mining method without coal pillar reservation and roadway excavation.The stability control of automatically formed roadway is the key to the succ...Non-pillar mining technology with automatically formed roadway is a new mining method without coal pillar reservation and roadway excavation.The stability control of automatically formed roadway is the key to the successful application of the new method.In order to realize the stability control of the roadway surrounding rock,the mechanical model of the roof and rib support structure is established,and the influence mechanism of the automatically formed roadway parameters on the compound force is revealed.On this basis,the roof and rib support structure technology of confined lightweight concrete is proposed,and its mechanical tests under different eccentricity are carried out.The results show that the bearing capacity of confined lightweight concrete specimens is basically the same as that of ordinary confined concrete specimens.The bearing capacity of confined lightweight concrete specimens under different eccentricities is 1.95 times higher than those of U-shaped steel specimens.By comparing the test results with the theoretical calculated results of the confined concrete,the calculation method of the bearing capacity for the confined lightweight concrete structure is selected.The design method of confined lightweight concrete support structure is established,and is successfully applied in the extra-large mine,Ningtiaota Coal Mine,China.展开更多
To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to ac...To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to achieve online RUL prediction of slewing bearings,which consisted of a reliability based RUL prediction model and a data driven failure rate(FR) estimation model.Firstly,an RUL prediction model was developed based on modified Weibull distribution to build the relationship between RUL and FR.Secondly,principal component analysis(PCA) was introduced to process multi-dimensional life-cycle vibration signals,and continuous squared prediction error(CSPE) and its time-domain features were employed as equipment performance degradation features.Afterwards,an FR estimation model was established on basis of the degradation features and relevant FRs using simplified fuzzy adaptive resonance theory map(SFAM) neural network.Consequently,real-time FR of equipment can be obtained through FR estimation model,and then accurate RUL can be calculated through the RUL prediction model.Results of a slewing bearing life test show that CSPE is an effective indicator of performance degradation process of slewing bearings,and that by combining actual load condition and real-time monitored data,the calculation time is reduced by 87.3%and the accuracy is increased by 0.11%,which provides a potential for online RUL prediction of slewing bearings and other various machineries.展开更多
A hydroelectric power generator, which is able to extract the water flow energy from the hydroelastic response of an elastically supported rectangular wing, is experimentally investigated. An electric motor is used to...A hydroelectric power generator, which is able to extract the water flow energy from the hydroelastic response of an elastically supported rectangular wing, is experimentally investigated. An electric motor is used to excite pitching oscillations of the wing. Both the wing and the electric motor are supported by leaf springs which are designed to work both as a linear guide for the sway oscillations and as elastic elements. The wing mass in sway direction necessary to achieve a hydroelastic response is obtained by utilizing a mechanical snubber mechanism. The appropriate load to generate electricity is provided by magnetic dampers. In the previous paper, the generating power rate and the efficiency were examined through the experiments with a single wing model, and the feasibility of the flapping wing hydroelectric power generator was verified. In this paper, the influence of the neighboring wings is examined by using two experimental apparatuses, with the intention of achieving a practical cascade wing generator. Tests revealed that the cascade moving in-phase with the neighboring wings at narrower intervals has a higher rate of electric power generation.展开更多
In order to study the distribution of lateral floor abutment pressure at a working face,we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distri...In order to study the distribution of lateral floor abutment pressure at a working face,we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distribution.Second,we established a three-dimensional numerical simulation model of the Haizi Coal Mine No.86 mining area by using FLAC^（3D）（ITASCA Consulting Group） software.We investigated the distribution of lateral floor abutment pressure of a stope,which indicated that the position of abutment pressure peak varies at different floor depths.We then determined the rational reinforcement range of a floor roadway,based on the conclusion reached earlier.Finally,we used our conclusions in support of the No.86 mining area crossing-roadway.The supported crossing-roadway remained stable when mining the upper workface,which validates the accuracy of our numerical simulation and provides a future reference for the support of span-roadways under similar conditions.展开更多
基金Project(2023YFC2907600)supported by the National Key Research and Development Program of ChinaProjects(42077267,42277174,52074164)supported by the National Natural Science Foundation of ChinaProject(2024JCCXSB01)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Non-pillar mining technology with automatically formed roadway is a new mining method without coal pillar reservation and roadway excavation.The stability control of automatically formed roadway is the key to the successful application of the new method.In order to realize the stability control of the roadway surrounding rock,the mechanical model of the roof and rib support structure is established,and the influence mechanism of the automatically formed roadway parameters on the compound force is revealed.On this basis,the roof and rib support structure technology of confined lightweight concrete is proposed,and its mechanical tests under different eccentricity are carried out.The results show that the bearing capacity of confined lightweight concrete specimens is basically the same as that of ordinary confined concrete specimens.The bearing capacity of confined lightweight concrete specimens under different eccentricities is 1.95 times higher than those of U-shaped steel specimens.By comparing the test results with the theoretical calculated results of the confined concrete,the calculation method of the bearing capacity for the confined lightweight concrete structure is selected.The design method of confined lightweight concrete support structure is established,and is successfully applied in the extra-large mine,Ningtiaota Coal Mine,China.
基金Projects(51375222,51175242)supported by the National Natural Science Foundation of China
文摘To decrease breakdown time and improve machine operation reliability,accurate residual useful life(RUL) prediction has been playing a critical role in condition based monitoring.A data fusion method was proposed to achieve online RUL prediction of slewing bearings,which consisted of a reliability based RUL prediction model and a data driven failure rate(FR) estimation model.Firstly,an RUL prediction model was developed based on modified Weibull distribution to build the relationship between RUL and FR.Secondly,principal component analysis(PCA) was introduced to process multi-dimensional life-cycle vibration signals,and continuous squared prediction error(CSPE) and its time-domain features were employed as equipment performance degradation features.Afterwards,an FR estimation model was established on basis of the degradation features and relevant FRs using simplified fuzzy adaptive resonance theory map(SFAM) neural network.Consequently,real-time FR of equipment can be obtained through FR estimation model,and then accurate RUL can be calculated through the RUL prediction model.Results of a slewing bearing life test show that CSPE is an effective indicator of performance degradation process of slewing bearings,and that by combining actual load condition and real-time monitored data,the calculation time is reduced by 87.3%and the accuracy is increased by 0.11%,which provides a potential for online RUL prediction of slewing bearings and other various machineries.
文摘A hydroelectric power generator, which is able to extract the water flow energy from the hydroelastic response of an elastically supported rectangular wing, is experimentally investigated. An electric motor is used to excite pitching oscillations of the wing. Both the wing and the electric motor are supported by leaf springs which are designed to work both as a linear guide for the sway oscillations and as elastic elements. The wing mass in sway direction necessary to achieve a hydroelastic response is obtained by utilizing a mechanical snubber mechanism. The appropriate load to generate electricity is provided by magnetic dampers. In the previous paper, the generating power rate and the efficiency were examined through the experiments with a single wing model, and the feasibility of the flapping wing hydroelectric power generator was verified. In this paper, the influence of the neighboring wings is examined by using two experimental apparatuses, with the intention of achieving a practical cascade wing generator. Tests revealed that the cascade moving in-phase with the neighboring wings at narrower intervals has a higher rate of electric power generation.
基金supported by the National Basic Research Program of China(No.2010CB226805)the National Natural Science Foundation of China(Nos.50874103 and 50974115)+1 种基金the Natural Science Foundation of Jiangsu Province(No.KB2008135)the State Key Laboratory Fund(No.SKLGDUEK0905)
文摘In order to study the distribution of lateral floor abutment pressure at a working face,we first used elasticity theory to establish a distribution model of lateral floor abutment pressure and then analysed its distribution.Second,we established a three-dimensional numerical simulation model of the Haizi Coal Mine No.86 mining area by using FLAC^（3D）（ITASCA Consulting Group） software.We investigated the distribution of lateral floor abutment pressure of a stope,which indicated that the position of abutment pressure peak varies at different floor depths.We then determined the rational reinforcement range of a floor roadway,based on the conclusion reached earlier.Finally,we used our conclusions in support of the No.86 mining area crossing-roadway.The supported crossing-roadway remained stable when mining the upper workface,which validates the accuracy of our numerical simulation and provides a future reference for the support of span-roadways under similar conditions.
