Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formati...Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.展开更多
In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-ele...In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.展开更多
The separation characteristic of raw coal from Luoyang mining area, China, was investigated by applying a dry coal beneficiation flowsheet with the dense medium gas-solid fluidized bed as main separating equipment. Th...The separation characteristic of raw coal from Luoyang mining area, China, was investigated by applying a dry coal beneficiation flowsheet with the dense medium gas-solid fluidized bed as main separating equipment. The experimental and simulation results indicate that the dense medium gas-solid fluidized bed can provide uniform distribution and stable fluctuation of bed densities at various heights. Two types of different separating approaches were compared using the dry coal beneficiation flowsheet. Compared with obtaining cleaning coal in the first stage of the flowsheet, a higher yield of the cleaning coal and better separation efficiency can be achieved when discharging gangue in the first stage. Finally, the results indicate that 64.86% pure cleaning coal with an ash content of 11.77% and 13.53% middlings were obtained, and 21.61% gangue was removed in two successive separation stages with the probable errors of 0.05 and 0.07 g/cm3, respectively.展开更多
In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial n...In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.展开更多
The construction industry is acutely aware of the need to improve its management process. Currently,construction management is facing four major schools of thoughts. This paper reports the recent study results,the aim...The construction industry is acutely aware of the need to improve its management process. Currently,construction management is facing four major schools of thoughts. This paper reports the recent study results,the aim of which was to compare these approaches. The focus will be on the questions:What is the theory root for this school of thoughts? What is the position of planning? What are the techniques used or recommended by each of these schools of thoughts in managing construction projects? Recommendations are then given through a deep discussion of the capability of each approach in managing today's highly complex construction project.展开更多
I want to know God’s thoughts.The rest are details. Albert Einstein The first reference to landslides deeply goes long far for ages.For centuries mankind try to solve the secret of landslides and get answers to quest...I want to know God’s thoughts.The rest are details. Albert Einstein The first reference to landslides deeply goes long far for ages.For centuries mankind try to solve the secret of landslides and get answers to questions:Where?When?How?Where could the nature have hidden the keys to landslide secret? Perhaps the latest achievements of science and technology could bring us closer to the clues of展开更多
Low carbon agriculture is a new production mode of green agriculture development to face the challenge of the global climate change, and a kind of innovation on developing circular agriculture. Up to now, low carbon a...Low carbon agriculture is a new production mode of green agriculture development to face the challenge of the global climate change, and a kind of innovation on developing circular agriculture. Up to now, low carbon agricultural development approaches are lacking of deep and systematical researches. Therefore, the paper briefly analyzed the situation and the existing problems of China＇s low carbon agricultural development, and then put forward the approaches to promote the low carbon agricultural development.展开更多
This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod ...This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.展开更多
The development and wide application of genetic transformation for cotton improvement are restrained by the unresolved problem of genotype dependence in regeneration in vitro.High embryogenic and regenerative potentia...The development and wide application of genetic transformation for cotton improvement are restrained by the unresolved problem of genotype dependence in regeneration in vitro.High embryogenic and regenerative potential have been obtained for limited number of Coker type genotypes。展开更多
The one-dimensional understanding of political efficacy has developed into the two-dimensional understanding,including the internal efficacy and the external efficacy.There are various measurements concerning politica...The one-dimensional understanding of political efficacy has developed into the two-dimensional understanding,including the internal efficacy and the external efficacy.There are various measurements concerning political efficacy researched and acceptable abroad.In China,scholars localize such measurements in order to adapt to the Chinese national conditions.After researches from the perspective of sociology,social psychology,rational choice and participative behavior,scholars continue to research political efficacy from various perspectives.However,as far as the research perspective,research content and research approach are concerned,China still has a long way to go.展开更多
For the first time, the isogeometric analysis(IGA) approach is used to model and analyze free and forced vibrations of doubly-curved magneto-electro-elastic(MEE) composite shallow shell resting on the visco-Pasternak ...For the first time, the isogeometric analysis(IGA) approach is used to model and analyze free and forced vibrations of doubly-curved magneto-electro-elastic(MEE) composite shallow shell resting on the visco-Pasternak foundation in a hygro-temperature environment. The doubly-curved MEE shallow shell types include spherical shallow shell, cylindrical shallow shell, saddle shallow shell, and elliptical shallow shell subjected to blast load are investigated. The Maxwell equation and electromagnetic boundary conditions are used to determine the vary of the electric and magnetic potentials. The MEE shallow shell's equations of motion are derived from Hamilton's principle and refined higher-order shear theory. Then, the IGA method is used to derive the laws of natural frequencies and dynamic responses of the shell under various boundary conditions. The accuracy of the model and method is verified through reliable numerical comparisons. Aside from this, the impact of the input parameters on the free and forced vibration of the doubly-curved MEE shallow shell is examined in detail. These results may be useful in the design and manufacture of military structures such as warships, fighter aircraft, drones and missiles.展开更多
提高竞技体育人才培养效率是保障竞技体育健康稳定发展的重要途径。研究系统梳理了近年来优秀运动员发展环境(athletic talent development environment,ATDE)领域的理论进展和实证研究,从打造良好育人环境的角度,介绍了诸多环境因素在...提高竞技体育人才培养效率是保障竞技体育健康稳定发展的重要途径。研究系统梳理了近年来优秀运动员发展环境(athletic talent development environment,ATDE)领域的理论进展和实证研究,从打造良好育人环境的角度,介绍了诸多环境因素在运动员成功发展过程中的功能角色和重要性;基于整体生态学途径(holistic ecological approach,HEA)的理论与实证研究进展,分析了ATDE的结构和过程模型,以及环境因素的有效特征和无效特征;人才发展环境要素的良性功能和不良功能特征初步概念框架进一步揭示了环境因素对运动员发展的双向作用。研究认为,成功的ATDE具备支持性训练团队、明确的组织文化和整合各方努力的能力等,而无效的环境则缺乏这些特征。已有实证研究通过对具体运动员发展环境和特定环境要素进行分析,结合HEA等理论框架,从运动员、教练员等多个视角出发,探讨ATDE对运动成绩与运动员个人发展的影响。未来需关注跨文化研究、长期追踪研究、环境因素的综合评估,并强化实证研究的深度和广度。展开更多
基金Project(2022XDHZ12)supported by the Lvliang Technology Project,ChinaProjects(8232056,2232080)supported by the Beijing Natural Science Foundation,ChinaProject([2020]3008)supported by the Science and Technology Projects in Guizhou Province,China。
文摘Addressing the issues of significant entry settlement and severe mining pressure manifestations in the conventional 121 approach,an innovative N00 approach is proposed.By comparing the mining process and entry formation process of different approaches,the characteristics of entry roof settlement evolution under different approaches are obtained.The N00 approach,which incorporates roof cutting and NPR cable support,optimizes the mining and entry formation process to reduce the settlement phase of entry roof,decreases the settlement of entry roof,and enhances the steadiness of entry roof.The N00 approach modifies the entry roof structure through roof cutting and establishes a hydraulic support load mechanics model for the mining panel to derive the theoretical load pressure formula for the N00 approach’s hydraulic support.Compared with the conventional 121 approach,the pressure on the N00 approach’s hydraulic support is reduced.Empirical data obtained through field monitoring demonstrate that the N00 approach has reduced the roof settlement of the entry and weakened the mining pressure manifestation at the mining panel,achieving the goal of protecting the entry and mining panel.
文摘In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.
基金Projects(51221462)supported by the National Natural Science Foundation of ChinaProject(2014QNA28)supported by the Fundamental Research Funds for the Central Universities,China
文摘The separation characteristic of raw coal from Luoyang mining area, China, was investigated by applying a dry coal beneficiation flowsheet with the dense medium gas-solid fluidized bed as main separating equipment. The experimental and simulation results indicate that the dense medium gas-solid fluidized bed can provide uniform distribution and stable fluctuation of bed densities at various heights. Two types of different separating approaches were compared using the dry coal beneficiation flowsheet. Compared with obtaining cleaning coal in the first stage of the flowsheet, a higher yield of the cleaning coal and better separation efficiency can be achieved when discharging gangue in the first stage. Finally, the results indicate that 64.86% pure cleaning coal with an ash content of 11.77% and 13.53% middlings were obtained, and 21.61% gangue was removed in two successive separation stages with the probable errors of 0.05 and 0.07 g/cm3, respectively.
基金Project(2013CB035402) supported by the National Basic Research Program of ChinaProjects(51105048,51209028) supported by the National Natural Science Foundation of China
文摘In order to deal with modeling problem of a pressure balance system with time-delay, nonlinear, time-varying and uncertain characteristics, an intelligent modeling procedure is proposed, which is based on artificial neural network(ANN) and input-output data of the system during shield tunneling and can overcome the precision problem in mechanistic modeling(MM) approach. The computational results show that the training algorithm with Gauss-Newton optimization has fast convergent speed. The experimental investigation indicates that, compared with mechanistic modeling approach, intelligent modeling procedure can obviously increase the precision in both soil pressure fitting and forecasting period. The effectiveness and accuracy of proposed intelligent modeling procedure are verified in laboratory tests.
文摘The construction industry is acutely aware of the need to improve its management process. Currently,construction management is facing four major schools of thoughts. This paper reports the recent study results,the aim of which was to compare these approaches. The focus will be on the questions:What is the theory root for this school of thoughts? What is the position of planning? What are the techniques used or recommended by each of these schools of thoughts in managing construction projects? Recommendations are then given through a deep discussion of the capability of each approach in managing today's highly complex construction project.
文摘I want to know God’s thoughts.The rest are details. Albert Einstein The first reference to landslides deeply goes long far for ages.For centuries mankind try to solve the secret of landslides and get answers to questions:Where?When?How?Where could the nature have hidden the keys to landslide secret? Perhaps the latest achievements of science and technology could bring us closer to the clues of
文摘Low carbon agriculture is a new production mode of green agriculture development to face the challenge of the global climate change, and a kind of innovation on developing circular agriculture. Up to now, low carbon agricultural development approaches are lacking of deep and systematical researches. Therefore, the paper briefly analyzed the situation and the existing problems of China＇s low carbon agricultural development, and then put forward the approaches to promote the low carbon agricultural development.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272257,12102292,12032006)the special fund for Science and Technology Innovation Teams of Shanxi Province(Nos.202204051002006).
文摘This study employs a data-driven methodology that embeds the principle of dimensional invariance into an artificial neural network to automatically identify dominant dimensionless quantities in the penetration of rod projectiles into semi-infinite metal targets from experimental measurements.The derived mathematical expressions of dimensionless quantities are simplified by the examination of the exponent matrix and coupling relationships between feature variables.As a physics-based dimension reduction methodology,this way reduces high-dimensional parameter spaces to descriptions involving only a few physically interpretable dimensionless quantities in penetrating cases.Then the relative importance of various dimensionless feature variables on the penetration efficiencies for four impacting conditions is evaluated through feature selection engineering.The results indicate that the selected critical dimensionless feature variables by this synergistic method,without referring to the complex theoretical equations and aiding in the detailed knowledge of penetration mechanics,are in accordance with those reported in the reference.Lastly,the determined dimensionless quantities can be efficiently applied to conduct semi-empirical analysis for the specific penetrating case,and the reliability of regression functions is validated.
文摘The development and wide application of genetic transformation for cotton improvement are restrained by the unresolved problem of genotype dependence in regeneration in vitro.High embryogenic and regenerative potential have been obtained for limited number of Coker type genotypes。
基金the phased achievement of the youth project of the humanities and social science research of the Ministry of Education-Empirical Analysis of the Village Committee Election of A County in 2011.(No.:10YJC810020)
文摘The one-dimensional understanding of political efficacy has developed into the two-dimensional understanding,including the internal efficacy and the external efficacy.There are various measurements concerning political efficacy researched and acceptable abroad.In China,scholars localize such measurements in order to adapt to the Chinese national conditions.After researches from the perspective of sociology,social psychology,rational choice and participative behavior,scholars continue to research political efficacy from various perspectives.However,as far as the research perspective,research content and research approach are concerned,China still has a long way to go.
文摘For the first time, the isogeometric analysis(IGA) approach is used to model and analyze free and forced vibrations of doubly-curved magneto-electro-elastic(MEE) composite shallow shell resting on the visco-Pasternak foundation in a hygro-temperature environment. The doubly-curved MEE shallow shell types include spherical shallow shell, cylindrical shallow shell, saddle shallow shell, and elliptical shallow shell subjected to blast load are investigated. The Maxwell equation and electromagnetic boundary conditions are used to determine the vary of the electric and magnetic potentials. The MEE shallow shell's equations of motion are derived from Hamilton's principle and refined higher-order shear theory. Then, the IGA method is used to derive the laws of natural frequencies and dynamic responses of the shell under various boundary conditions. The accuracy of the model and method is verified through reliable numerical comparisons. Aside from this, the impact of the input parameters on the free and forced vibration of the doubly-curved MEE shallow shell is examined in detail. These results may be useful in the design and manufacture of military structures such as warships, fighter aircraft, drones and missiles.
