Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick ha...Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.展开更多
The system of equation discussed in this paper is a model that describes the phenomena of El Nino and Southern Oscillation （ENSO）. The stability of this model is studied with the method of stratification theory. A n...The system of equation discussed in this paper is a model that describes the phenomena of El Nino and Southern Oscillation （ENSO）. The stability of this model is studied with the method of stratification theory. A necessary and sufficient condition to justify whether an initial （boundary） problem is well posed or not is also obtained.展开更多
It is proved that the ill-posed initial value problem of the Euler equations for compressible adiabatic inviscid fluid flow can be only formally solved. The necessary and sufficient conditions for existence of formal ...It is proved that the ill-posed initial value problem of the Euler equations for compressible adiabatic inviscid fluid flow can be only formally solved. The necessary and sufficient conditions for existence of formal solution of some representative ill-posedness initial-boundary value problem are presented. Finally, an example is also given.展开更多
The well-posedness of the initial value problem of the Euler equations was mainly discussed based on the stratification theory, and the necessary and sufficient conditions of well-posedness are presented for some repr...The well-posedness of the initial value problem of the Euler equations was mainly discussed based on the stratification theory, and the necessary and sufficient conditions of well-posedness are presented for some representative initial or boundary value problem, thus the structure of solution space for local （exact） solution of the Euler equations is determined. Moreover the computation formulas of the analytical solution of the well-posed problem are also given.展开更多
One type of evolution atmosphere equations was discussed. It is found that according to the stratification theory, （i） the inertial force has no influence on the criterion of the well-posed Cauchy problem; （ii） th...One type of evolution atmosphere equations was discussed. It is found that according to the stratification theory, （i） the inertial force has no influence on the criterion of the well-posed Cauchy problem; （ii） the compressibility plays no role on the well-posed condition of the Cauchy problem of the viscid atmosphere equations, but changes the well-posed condition of the viscid atmosphere equations; （iii） this type of atmosphere evolution equations is ill-posed on the hyperplane t = 0 in spite of its compressibility and viscosity; （iv） the Cauchy problem of compressible viscosity atmosphere with still initial motion is ill-posed.展开更多
Despite the expansion of Chinese education and the steady rise in the educational level of urban and rural residents since reform and opening up, the problem of educational inequality has persisted. This study employs...Despite the expansion of Chinese education and the steady rise in the educational level of urban and rural residents since reform and opening up, the problem of educational inequality has persisted. This study employs CGSS2008 data to test the effects of household registration, family socio-economic status, years of parental education, and sibship size on educational opportunity at the three stages of junior middle school, senior middle school and higher education, as well as the changes in these effects over the period 1978-2008. The results show that there is no observable rural-urban disparity in opportunities for continuation to the junior middle school stage, but there is rising inequality in opporUmities for continuation to senior middle school and higher education; the influence of father＇s occupational status on children＇s educational opportunities remains largely the same, indicating that the stratification of educational attainment has not changed markedly since 1978： years of varental education play a marked and increasing role in children＇s educational attainment; and educational inequality due to sibship size also displays a rising tendency. To understand the structure and evolution of inequality in Chinese education since reform and opening up, it is necessary to study the micro-level mechanisms affecting residents＇ educational decision-making.展开更多
西方学术界对斯特拉文斯基《春之祭》音乐的研究和争论已经持续了一个多世纪,美国音乐理论家凡·顿·托恩教授的《再谈〈春之祭〉》(“The Rite of Spring Briefly Revisited:Thoughts on Stravinsky’s Stratifications,the Ps...西方学术界对斯特拉文斯基《春之祭》音乐的研究和争论已经持续了一个多世纪,美国音乐理论家凡·顿·托恩教授的《再谈〈春之祭〉》(“The Rite of Spring Briefly Revisited:Thoughts on Stravinsky’s Stratifications,the Psychology of Meter,and African Polyrhythm”)一文,展示出他本人的最新研究成果。这篇导读是对20世纪60年代以来,特别是80年代以后西方(主要是美国)学术界对斯特拉文斯基《春之祭》这部作品研究情况的综述,涉及到对《春之祭》音乐创作分析解读的三种不同切入视点、分析方法及其争论点。并且,还通过简述引入到国内的其它文献资源及国内学者的研究,使读者能够从宏观上了解到国内外各方对《春之祭》音乐研究的立场和观点以及托恩教授写这篇文章的意图。展开更多
基金the Beijing Outstanding Young Scientist Program of China(No.BJJWZYJH01201911413037)projects(Nos.41877257 and 51622404)supported by National Natural Science Foundation of China+1 种基金Shaanxi Coal Group Key Project of China(No.2018SMHKJ-A-J-03)the Fundamental Research Funds for the Central Universities of China(No.2021YJSLJ23)。
文摘Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.
基金supported by the National Natural Science Foundation of China (Grant No.90411006)
文摘The system of equation discussed in this paper is a model that describes the phenomena of El Nino and Southern Oscillation （ENSO）. The stability of this model is studied with the method of stratification theory. A necessary and sufficient condition to justify whether an initial （boundary） problem is well posed or not is also obtained.
基金Project supported by the National Natural Science Foundation of China （Major Program of the Tenth Five-Year Plan） （Grant No,90411006）
文摘It is proved that the ill-posed initial value problem of the Euler equations for compressible adiabatic inviscid fluid flow can be only formally solved. The necessary and sufficient conditions for existence of formal solution of some representative ill-posedness initial-boundary value problem are presented. Finally, an example is also given.
文摘The well-posedness of the initial value problem of the Euler equations was mainly discussed based on the stratification theory, and the necessary and sufficient conditions of well-posedness are presented for some representative initial or boundary value problem, thus the structure of solution space for local （exact） solution of the Euler equations is determined. Moreover the computation formulas of the analytical solution of the well-posed problem are also given.
基金Project supported by the National Natural Science Foundation of China (Nos.40233027 and 90411006)the National Natural Science Foundation of China (Major Program) (No.90411006)
文摘One type of evolution atmosphere equations was discussed. It is found that according to the stratification theory, （i） the inertial force has no influence on the criterion of the well-posed Cauchy problem; （ii） the compressibility plays no role on the well-posed condition of the Cauchy problem of the viscid atmosphere equations, but changes the well-posed condition of the viscid atmosphere equations; （iii） this type of atmosphere evolution equations is ill-posed on the hyperplane t = 0 in spite of its compressibility and viscosity; （iv） the Cauchy problem of compressible viscosity atmosphere with still initial motion is ill-posed.
基金is the outcome of "A Study of the Impact of Modern Education on Social Stratification and Mobility"(CFA090096),a topic for young scholars of education under the 11th Five-year Plan of the National Social Science Fund,with support from both the "Program for Supporting Outstanding Talent of the New Century"(2011) of the Ministry of Education and "Research on Educational Equality in China,"a major Shandong University project in the humanities and social sciences
文摘Despite the expansion of Chinese education and the steady rise in the educational level of urban and rural residents since reform and opening up, the problem of educational inequality has persisted. This study employs CGSS2008 data to test the effects of household registration, family socio-economic status, years of parental education, and sibship size on educational opportunity at the three stages of junior middle school, senior middle school and higher education, as well as the changes in these effects over the period 1978-2008. The results show that there is no observable rural-urban disparity in opportunities for continuation to the junior middle school stage, but there is rising inequality in opporUmities for continuation to senior middle school and higher education; the influence of father＇s occupational status on children＇s educational opportunities remains largely the same, indicating that the stratification of educational attainment has not changed markedly since 1978： years of varental education play a marked and increasing role in children＇s educational attainment; and educational inequality due to sibship size also displays a rising tendency. To understand the structure and evolution of inequality in Chinese education since reform and opening up, it is necessary to study the micro-level mechanisms affecting residents＇ educational decision-making.
文摘西方学术界对斯特拉文斯基《春之祭》音乐的研究和争论已经持续了一个多世纪,美国音乐理论家凡·顿·托恩教授的《再谈〈春之祭〉》(“The Rite of Spring Briefly Revisited:Thoughts on Stravinsky’s Stratifications,the Psychology of Meter,and African Polyrhythm”)一文,展示出他本人的最新研究成果。这篇导读是对20世纪60年代以来,特别是80年代以后西方(主要是美国)学术界对斯特拉文斯基《春之祭》这部作品研究情况的综述,涉及到对《春之祭》音乐创作分析解读的三种不同切入视点、分析方法及其争论点。并且,还通过简述引入到国内的其它文献资源及国内学者的研究,使读者能够从宏观上了解到国内外各方对《春之祭》音乐研究的立场和观点以及托恩教授写这篇文章的意图。
