期刊文献+
共找到1,377篇文章
< 1 2 69 >
每页显示 20 50 100
Overburden fracture evolution laws and water-controlling technologies in mining very thick coal seam under water-rich roof 被引量:8
1
作者 Zhang Youxi Tu Shihao +1 位作者 Bai Qingsheng Li Jianjun 《International Journal of Mining Science and Technology》 SCIE EI 2013年第5期693-700,共8页
Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution l... Considering the danger of water inrush in mining very thick coal seam under water-rich roof in Majialiang Coal Mine,the universal discrete element(UDEC)software was used to simulate the overburden fracture evolution laws when mining 4#coal seam.Besides,this study researched on the influence of face advancing length,speed and mining height on the height of the water flowing fractured zones(HWFFZ),and analyzed the correlation of face advancing length and change rules of aquifer water levels and goaf water inflow.Based on those mentioned above,this research proposed the following water-controlling technologies:draining the roof water before mining,draining goaf water,reasonable advancing speed and mining thickness.These water-controlling technologies were successfully used in the feld,thus ensured safely mining the very thick coal seam under water-rich roof. 展开更多
关键词 Water-rich roof Very thick coal seam Mining induced fracture evolution law Water-controlling technology
下载PDF
Route strategy of satellite network in GNSS based on topology evolution law 被引量:2
2
作者 Xianqing Yi Zhenwei Hou +2 位作者 Tao Zhong Yaohong Zhang Zhili Sun 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第4期596-608,共13页
As each type of satellite network has different link features, its data transmission must be designed based on its link features to improve the efficiency of data transferring. The transmission of navigation integrate... As each type of satellite network has different link features, its data transmission must be designed based on its link features to improve the efficiency of data transferring. The transmission of navigation integrated services information (NISI) in a global navigation satellite system (GNSS) with inter-satellite links (ISLs) is studied by taking the real situation of inter-satellite communication links into account. An on-demand computing and buffering centralized route strategy is proposed based on dynamic grouping and the topology evolution law of the GNSS network within which the satellite nodes are operated in the manner of dynamic grouping. Dynamic grouping is based on satellites spatial relationships and the group role of the satellite node changes by turns due to its spatial relationships. The route strategy provides significant advantages of high efficiency, low complexity, and flexi- ble configuration, by which the established GNSS can possess the features and capabilities of feasible deployment, efficient transmission, convenient management, structural invulnerability and flexible expansion. 展开更多
关键词 satellite navigation evolution law route strategy.
下载PDF
A numerical study of comparison of two one-state-variable,rate-and state-dependent friction evolution laws 被引量:2
3
作者 Jeen-Hwa Wang 《Earthquake Science》 CSCD 2009年第2期197-204,共8页
The two one-state-variable, rate- and state-dependent friction laws, i.e., the slip and slowness laws, are com- pared on the basis of dynamical behavior of a one-degree-of-freedom spring-slider model through numerical... The two one-state-variable, rate- and state-dependent friction laws, i.e., the slip and slowness laws, are com- pared on the basis of dynamical behavior of a one-degree-of-freedom spring-slider model through numerical simulations. Results show that two (normalized) model parameters, i.e., A (the normalized characteristic slip distance) and β-α (the difference in two normalized parameters of friction laws), control the solutions. From given values of △, β, and α, for the slowness laws, the solution exists and the unique non-zero fixed point is stable when △〉(β-α), yet not when △ 〈(β-α). For the slip law, the solution exists for large ranges of model parameters and the number and stability of the non-zero fixed points change from one case to another. Results suggest that the slip law is more appropriate for controlling earthquake dynamics than the slowness law. 展开更多
关键词 one-state-variable rate- and state-dependent friction law direct effect evolution effect characteristic slip displacement
下载PDF
A Study on Dual-Load-Zone Model of Overlying Strata andEvolution Law of Mining Stress 被引量:2
4
作者 Yuejin Zhou Mingpeng Li +1 位作者 Xiaoding Xu Meng Li 《Computers, Materials & Continua》 SCIE EI 2019年第2期391-407,共17页
The changeable structure and movement law of overlying strata are the maincontributor to the change of mining stress.Starting from the relevant theory of keystratum and particularly based on the theory of mine ground ... The changeable structure and movement law of overlying strata are the maincontributor to the change of mining stress.Starting from the relevant theory of keystratum and particularly based on the theory of mine ground pressure and strata control,this research proposed a new solution to mining stress problems by establishing adual-load-zone stratum structural model.Elastic foundation beam theory was used tosolve the stress of overlying strata of the dual-load-zones with superposition method,which revised the traditional calculation method of mining stress.The abnormal increaseof lead abutment pressure in the mining area was explained effectively,through which theevolution law of mining stress in the case of hard rock was obtained.The results indicatethat mining stress experiences a drastic change within the range of 50 m ahead of the coalwall due to the collapse of main roof;under the influence of main key stratum andinferior key strata,the influence range of lead abutment pressure is extended up toapproximately 120 m in the working face;this remarkable increase can be attributed tothe excessive length of sagging zone.Results from both the dual-load-zone modelexperiment and field measurement demonstrate high consistency.The model can predictthe influence range of abutment pressure effectively and thus guide the safety productionof mining. 展开更多
关键词 Overlying strata structure dual-load-zone mining stress evolution law
下载PDF
Generation and Evolution of Cavitation Bubbles in Volume Alternate Cavitation(VAC)
5
作者 Shangshuang Chen Yun Wang +4 位作者 Fuzhu Li Shenwei Xue Zhenying Xu Chao Yu Kun Zhang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第3期241-251,共11页
Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore t... Cavitation generation methods have been used in multifarious directions because of their diversity,and numerous studies and discussions have been conducted on cavitation generation methods.This study aims to explore the generating mechanism and evolution law of volume alternate cavitation(VAC).In the VAC,liquid water is placed in an airtight container with a variable volume.As the volume alternately changes,the liquid water inside the container continues to cavitate.Then,the mixture turbulence model and in-cylinder dynamic grid model are adopted to conduct computational fluid dynamics simulation of volume alternate cavitation.In the simulation,the cloud images at seven heights on the central axis are monitored,and the phenomenon and mechanism of height and eccentricity are analyzed in detail.By employing the cavitation flow visualization method,the generating mechanism and evolution law of cavitation are revealed.The synergistic effects of experiments and high-speed camera capturing confirm the correctness of the simulation results.In the experiment,the volume change stroke of the airtight container is set to 20 mm,the volume change frequency is 18 Hz,and the shooting frequency of the high-speed camera is set to 10000 FPS.The experimental results indicate that the position of the cavitation phenomenon has a reasonable law during the whole evolution cycle of the cavitation cloud.Also,the volume alternation cycle corresponds to the generation,development,and collapse stages of cavitation bubbles. 展开更多
关键词 Cavitation generation method Volume alternate cavitation(VAC) Generating mechanism evolution law Computational fluid dynamics(CFD) Cavitation flow visualization(CFV)
下载PDF
Geographical Names as Cultural Symbols:The Law of Naming System’s Evolution in Southwest China 被引量:1
6
作者 Wang Hao 《学术界》 CSSCI 北大核心 2020年第12期228-234,共7页
In this paper,the geographic name in Southwest China is regarded as a symbolic representation of human beings,and the dynamic social and historical process behind the place names is restored from the perspective of th... In this paper,the geographic name in Southwest China is regarded as a symbolic representation of human beings,and the dynamic social and historical process behind the place names is restored from the perspective of the symbolic anthropology.There are three paths in the construction and evolution of geographic names in Southwest China—Ethnic information,sacred systems,and local representation,which have been rewritten,masked,and reconstructed over the years.As a result,the system of geographical names is gradually formed and integrated into local memory through space building,culture filling,and so on,affecting and influencing local group identity and cognitive concept. 展开更多
关键词 naming system law of evolution Southwest China
下载PDF
Strength evolution law of cracked rock based on localized progressive damage model 被引量:4
7
作者 张平 李夕兵 李宁 《Journal of Central South University of Technology》 EI 2008年第4期493-497,共5页
In the light of the localized progressive damage model,the evolution law of cohesive and frictional strength with irreversible strains was determined.Then,the location and the extent of the excavation disturbed zone i... In the light of the localized progressive damage model,the evolution law of cohesive and frictional strength with irreversible strains was determined.Then,the location and the extent of the excavation disturbed zone in one deep rock engineering were predicted by using the strength evolution law.The theoretical result is close to the result of in-situ test.The strength evolution law excels the elastic-perfectly plastic model and elasto-brittle plastic model in which the cohesive and frictional strength are mobilized simultaneously.The results obtained indicate that the essential failure mechanism of the cracked rock can be described by the cohesion weakening and friction strengthening evolution law. 展开更多
关键词 岩石力学 强度 地方化 进化方式
下载PDF
Stress field evolution law of mining environment reconstructing structure with change of filling height 被引量:1
8
作者 陈庆发 周科平 王利利 《Journal of Central South University》 SCIE EI CAS 2010年第4期738-743,共6页
For improving global stability of mining environment reconstructing structure,the stress field evolution law of the structure with the filling height change of low-grade backfill was studied by ADINA finite element an... For improving global stability of mining environment reconstructing structure,the stress field evolution law of the structure with the filling height change of low-grade backfill was studied by ADINA finite element analysis code.Three kinds of filling schemes were designed and calculated,in which the filling heights were 2,4,and 7 m,separately.The results show that there are some rules in the stress field with the increase of the filling height as follows:(1) the maximum value of tension stress of the roof decreases gradually,and stress conditions are improved gradually;(2) the tension stress status in the vertical pillar is transformed into the compressive stress status,and the carrying capacity is improved gradually;however,when the filling height is beyond 2.8 m,the carrying capacity of the vertical pillar grows very slowly,so,there is little significance to continue to fill the low-grade backfill;(3) the bottom pillar suffers the squeezing action from the vertical pillars at first and then the gravity action of the low-grade backfill,and the maximum value of tension stress of the bottom pillar firstly increases and then decreases.Considering the economic factor,security and other factors,the low-grade backfill has the most reasonable height(2.8 m) in the scope of all filling height. 展开更多
关键词 环境应力场 结构重建 填充 演化规律 改造 矿山 承载能力 填土高度
下载PDF
New approach for obtaining the time-evolution law of a chaotic light field in a damping gaining-process
9
作者 龚黎华 周南润 +1 位作者 胡利云 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第8期31-33,共3页
A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p(... A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator p(t) is derived and the solution of f for the damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance. 展开更多
关键词 chaotic light field damping gaining process time evolution law quantum communication
下载PDF
Spiral Wave Law Is Involved in the Unification of Four Fundamental Forces and the Origin and the Evolution of the Universe
10
作者 Jiapei Dai 《Natural Science》 2017年第9期306-311,共6页
A long-term goal of theoretical physics is to develop a single simple theory or model that would unify the four known fundamental forces (or interactions) and give explanations for the origin and the evolution of the ... A long-term goal of theoretical physics is to develop a single simple theory or model that would unify the four known fundamental forces (or interactions) and give explanations for the origin and the evolution of the Universe. Here a “spiral wave law” has been proposed based on the previous studies that a consistent universe field presents various forms of spiral (helical) wave motions at the speed of light (c), and therefore, a mathematical equation for the relationship between the radius of a spiral wave motion (r) and its wave length (λ) is derived including a simplified formula ( or ), which could provide a novel explanation for the origin and the evolution of the Universe, and the space-time relationships. This model may give a new way for the unification of four fundamental forces and determine the moving properties of galaxies and basic particles, and the propagation characteristics of electromagnetic waves at the large or small scale. 展开更多
关键词 Spiral Wave law FUNDAMENTAL FORCES ORIGIN and the evolution of the UNIVERSE
下载PDF
Hamiltonian Structure, Soliton Solution and Conservation Laws for a New Fifth-Order Nonlinear Evolution Equation Which Describes Pseudo-Spherical Surfaces
11
作者 S. M. Sayed N. O. Al-Atawi 《American Journal of Computational Mathematics》 2017年第2期166-174,共9页
In this paper, we shall show that the Hamiltonian structure can be defined for any nonlinear evolution equations which describe surfaces of a constant negative curvature, so that the densities of conservation laws can... In this paper, we shall show that the Hamiltonian structure can be defined for any nonlinear evolution equations which describe surfaces of a constant negative curvature, so that the densities of conservation laws can be considered as corresponding Hamiltonians. This paper obtains the soliton solution and conserved quantities of a new fifth-order nonlinear evolution equation by the aid of inverse scattering method. 展开更多
关键词 Nonlinear evolution Equations Conservation lawS Pseudo-Spherical Surfaces
下载PDF
Time evolution law of a two-mode squeezed light field passing through twin diffusion channels
12
作者 余海军 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第2期196-200,共5页
We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,... We explore the time evolution law of a two-mode squeezed light field(pure state)passing through twin diffusion channels,and we find that the final state is a squeezed chaotic light field(mixed state)with entanglement,which shows that even though the two channels are independent of each other,since the two modes of the initial state are entangled with each other,the final state remains entangled.Nevertheless,although the squeezing(entanglement)between the two modes is weakened after the diffusion,it is not completely removed.We also highlight the law of photon number evolution.In the calculation process used in this paper,we make full use of the summation method within the ordered product of operators and the generating function formula for two-variable Hermite polynomials. 展开更多
关键词 two-mode squeezed light field twin diffusion channels time evolution law entanglement
下载PDF
Simulation Test for Evolution Laws of Tensile Fractures in a Coal Mining Area
13
作者 Zhang Jinman Zhang Kun +2 位作者 Li Jiewei Zhao Ling Zhou Liang 《Meteorological and Environmental Research》 CAS 2018年第4期85-88,共4页
In order to study evolution laws of tensile fractures in a coal mining area, based on the classification of the fractures formed by mining, a physical simulation test was carried out to simulate the dynamic evolut... In order to study evolution laws of tensile fractures in a coal mining area, based on the classification of the fractures formed by mining, a physical simulation test was carried out to simulate the dynamic evolution process of tensile fractures in coal mining areas. The results showed that after the coal in the mining area was mined, the mining area underwent obvious movement and deformation and forms tensile fractures. As the min-ing working face was advanced, the tensile fractures underwent the dynamic process of generation, development and closure. The changing curves of density of tensile fractures with the increase of mining length of the working face liked a ladder (it increased slowly and then rapidly) and then had two peaks (the second peak was higher than the first peak). 展开更多
关键词 Coal mining areas Physical simulation Parallel electric method Tensile fractures evolution laws
下载PDF
Kinetic evolutionary behavior of catalysis-select migration 被引量:1
14
作者 吴远刚 林振权 柯见洪 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期531-537,共7页
We propose a catalysis-select migration driven evolution model of two-species(A-and B-species) aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts ... We propose a catalysis-select migration driven evolution model of two-species(A-and B-species) aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts of species D the reaction will become one unit of species B migrating to species A.Meanwhile the catalyst aggregates of species C perform self-coagulation,as do the species D aggregates.We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K(k;i,j) = Kkij and D species catalysis-select migration rate kernel J(k;i,j) = Jkij.The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration,in which the competition is between JD0 and KC0(D0 and C0 are the initial numbers of the monomers of species D and C,respectively).When JD0 KC0 〉 0,the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form.And in the case of JD0 KC0 〈 0,species A and B exchange their aggregate size distributions as in the above JD0 KC0 〉 0 case. 展开更多
关键词 catalysis-select migration kinetic evolution behavior rate equation scaling law
下载PDF
Time evolution of a squeezed chaotic field in an amplitude damping channel when used as a generating field for a squeezed number state 被引量:4
15
作者 徐兴磊 李洪奇 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第7期106-109,共4页
We investigate how an optical squeezed chaotic field(SCF) evolves in an amplitude dissipation channel. We have used the integration within ordered product of operators technique to derive its evolution law. We also ... We investigate how an optical squeezed chaotic field(SCF) evolves in an amplitude dissipation channel. We have used the integration within ordered product of operators technique to derive its evolution law. We also show that the density operator of SCF can be viewed as a generating field of the squeezed number state. 展开更多
关键词 squeezed chaotic field amplitude damping channel squeezed number state evolution law
下载PDF
A Maple Package on Symbolic Computation of Conserved Densities for (1+l)-Dimensional Nonlinear Evolution Systems 被引量:3
16
作者 YANG Xu-Dong RUAN Hang-Yu LOU Sen-Yue 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第6期961-968,共8页
关键词 (1+l)-维非线性进化系统 守恒定律 符号计算 计算机代数 Maple软件包
下载PDF
Fractal characterization for the mining crack evolution process of overlying strata based on microseismic monitoring technology 被引量:4
17
作者 Liu Chao Xue Junhu +1 位作者 Yu Guofeng Cheng Xiaoyu 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2016年第2期295-299,共5页
In order to study the evolution laws during the development process of the coal face overburden rock mining-induced fissure,we studied the process of evolution of overburden rock mining-induced fissures and dynamicall... In order to study the evolution laws during the development process of the coal face overburden rock mining-induced fissure,we studied the process of evolution of overburden rock mining-induced fissures and dynamically quantitatively described its fractal laws,based on the high-precision microseismic monitoring method and the nonlinear Fractal Geometry Theory.The results show that:the overburden rock mining-induced fissure fractal dimension experiences two periodic change processes with the coal face advance,namely a Small→ Big→ Small process,which tends to be stable;the functional relationship between the extraction step distance and the overburden rock mining-induced fissure fractal dimension is a cubic curve.The results suggest that the fractal dimension reflects the evolution characteristics of the overburden rock mining-induced fissure,which can be used as an evaluation index of the stability of the overburden rock strata,and it provides theoretical guidance for stability analysis of the overburden rock strata,goaf roof control and the support movements in the mining face. 展开更多
关键词 岩石裂隙 上覆地层 演化过程 分形特征 监测技术 微震 稳定性分析 采场覆岩
下载PDF
Thin Film Evolution Equation for a Strained Anisotropic Solid Film on a Deformable Isotropic Substrate
18
作者 Wondimu Tekalign Agegnehu Atena 《Journal of Applied Mathematics and Physics》 2018年第4期864-879,共16页
We consider a continuum model for the evolution of an epitaxially-strained dislocation-free anisotropic thin solid film on isotropic deformable substrate in the absence of vapor deposition. By using a thin film approx... We consider a continuum model for the evolution of an epitaxially-strained dislocation-free anisotropic thin solid film on isotropic deformable substrate in the absence of vapor deposition. By using a thin film approximation we derived a nonlinear evolution equation. We examined the nonlinear evolution equation and found that there is a critical film thickness below which every film thickness is stable and a critical wave number above which every film thickness is stable. 展开更多
关键词 Thin Films evolution Equation ANISOTROPY Hooke’s law
下载PDF
Physicochemical Stages of Evolution: Ring-Like Structures in the Universe
19
作者 Georgi P. Gladyshev 《Natural Science》 2015年第5期266-269,共4页
This short digest is devoted to the mechanism of ring formation during the origination and evolution of planetary and satellite systems in the Universe. The appearance of these structures can be traced back to the phe... This short digest is devoted to the mechanism of ring formation during the origination and evolution of planetary and satellite systems in the Universe. The appearance of these structures can be traced back to the phenomenon of spatially periodic condensation which can be observed on the Earth. The author actually posited the existence of exoplanetary systems and the cosmic scale of this phenomenon. It was accurately predicted that Uranus, Neptune and other heavenly bodies have rings. The suggested general mechanism rationalized the Titius-Bode law which, while not being a precise law, often accurately describes the tendency towards varying distances between planets (and their moons) and central bodies. The possibility of this law manifestation in exoplanetary systems had been predicted by the author long before their discovery. Many exoplanetary systems have been discovered by now and there is some evidence corroborating the mechanism of spatially periodic condensation involved in the formation of ring-like structures in these systems. The author’s hypothesis is now becoming a theory or a fact. It appears that we are now witnessing the dawn of a new extensive cosmology, taking into account general physicochemical mechanisms of space object formation. 展开更多
关键词 COSMOLOGY evolution Exoplanetary Systems Liesegang Phenomenon Solar System Titius-Bode law
下载PDF
Spatial Pattern and Evolution of Urbanization in Shandong Province
20
作者 LIU Chenxi WANG Linlin 《Journal of Landscape Research》 2018年第3期19-23,共5页
Based on Arc GIS and SPSS Statistics,authors of this paper used the principal component analysis(PCA) and the analytic hierarchy process(AHP),and selected 6 indicators concerning population,land,and economy to study t... Based on Arc GIS and SPSS Statistics,authors of this paper used the principal component analysis(PCA) and the analytic hierarchy process(AHP),and selected 6 indicators concerning population,land,and economy to study the spatial pattern of urbanization and regional economic differences in Shandong Province,namely urban population,urban population density,construction land,area of urban districts,disposable income of residents,and added value of the tertiary industry.The development of urbanization in Shandong Province was measured by the proportion of urban population to the total population in 2000,2005,2010,and 2014 respectively.It is hoped that this paper will provide a theoretical basis for building an orderly regional spatial structure and coordinating regional urban decision-making. 展开更多
关键词 URBANIZATION Spatial pattern evolution law REGIONAL ECONOMIC DIFFERENCES
下载PDF
上一页 1 2 69 下一页 到第
使用帮助 返回顶部