The paper is devoted to the study of the gravitational collapse within the framework of the spherically symmetric problem in the Newton theory and general relativity on the basis of the pressure-free model of the cont...The paper is devoted to the study of the gravitational collapse within the framework of the spherically symmetric problem in the Newton theory and general relativity on the basis of the pressure-free model of the continuum. In application to the Newton gravitation theory, the analysis consists of three stages. First, we assume that the gravitational force is determined by the initial sphere radius and constant density and does not change in the process of the sphere collapse. The obtained analytical solution allows us to find the collapse time in the first approximation. Second, we construct the step-by-step process in which the gravitational force at a given time moment depends on the current sphere radius and density. The obtained numerical solution specifies the collapse time depending on the number of steps. Third, we find the exact value of the collapse time which is the limit of the step-by-step solutions and study the collapse and the expansion processes in the Newton theory. In application to general relativity, we use the space model corresponding to the special four-dimensional space which is Euclidean with respect to space coordinates and Riemannian with respect to the time coordinate only. The obtained solution specifies two possible scenarios. First, sphere contraction results in the infinitely high density with the finite collapse time, which does not coincide with the conventional result corresponding to the Schwarzschild geometry. Second, sphere expansion with the velocity which increases with a distance from the sphere center and decreases with time.展开更多
An association rules mining method based on semantic relativity is proposed to solve the problem that there are more candidate item sets and higher time complexity in traditional association rules mining.Semantic rela...An association rules mining method based on semantic relativity is proposed to solve the problem that there are more candidate item sets and higher time complexity in traditional association rules mining.Semantic relativity of ontology concepts is used to describe complicated relationships of domains in the method.Candidate item sets with less semantic relativity are filtered to reduce the number of candidate item sets in association rules mining.An ontology hierarchy relationship is regarded as a directed acyclic graph rather than a hierarchy tree in the semantic relativity computation.Not only direct hierarchy relationships,but also non-direct hierarchy relationships and other typical semantic relationships are taken into account.Experimental results show that the proposed method can reduce the number of candidate item sets effectively and improve the efficiency of association rules mining.展开更多
This paper presents the conservation law of Einstein's General Relativity, in whichthe continuity equation of matter and gravitational field is implicitly derived from theequation of motion of matter. Although the...This paper presents the conservation law of Einstein's General Relativity, in whichthe continuity equation of matter and gravitational field is implicitly derived from theequation of motion of matter. Although the obtained energy-momentum tensor is thesame as the Landau- Lifshitz pseudotensor. the physical and conceptual foundation aredifferent. Two alternative methods to obtain the gravitational radiation are proposed inthis paper as well The radiation will be derived from the equation of motion of matterand geodesic equation separately.展开更多
Sapir-Whorf Hypothesis is controversial, but the Linguistic Relativity is universally accepted by scholars. Through ana lyzing the causes of the mistakes that students often make during English learning and the relati...Sapir-Whorf Hypothesis is controversial, but the Linguistic Relativity is universally accepted by scholars. Through ana lyzing the causes of the mistakes that students often make during English learning and the relationship among thoughts, cultures and languages, this paper argues that language can influence people's thoughts and people's thoughts can influence the acquisi tion of a second language.展开更多
文摘The paper is devoted to the study of the gravitational collapse within the framework of the spherically symmetric problem in the Newton theory and general relativity on the basis of the pressure-free model of the continuum. In application to the Newton gravitation theory, the analysis consists of three stages. First, we assume that the gravitational force is determined by the initial sphere radius and constant density and does not change in the process of the sphere collapse. The obtained analytical solution allows us to find the collapse time in the first approximation. Second, we construct the step-by-step process in which the gravitational force at a given time moment depends on the current sphere radius and density. The obtained numerical solution specifies the collapse time depending on the number of steps. Third, we find the exact value of the collapse time which is the limit of the step-by-step solutions and study the collapse and the expansion processes in the Newton theory. In application to general relativity, we use the space model corresponding to the special four-dimensional space which is Euclidean with respect to space coordinates and Riemannian with respect to the time coordinate only. The obtained solution specifies two possible scenarios. First, sphere contraction results in the infinitely high density with the finite collapse time, which does not coincide with the conventional result corresponding to the Schwarzschild geometry. Second, sphere expansion with the velocity which increases with a distance from the sphere center and decreases with time.
基金The National Natural Science Foundation of China(No.50674086)Specialized Research Fund for the Doctoral Program of Higher Education(No.20060290508)the Science and Technology Fund of China University of Mining and Technology(No.2007B016)
文摘An association rules mining method based on semantic relativity is proposed to solve the problem that there are more candidate item sets and higher time complexity in traditional association rules mining.Semantic relativity of ontology concepts is used to describe complicated relationships of domains in the method.Candidate item sets with less semantic relativity are filtered to reduce the number of candidate item sets in association rules mining.An ontology hierarchy relationship is regarded as a directed acyclic graph rather than a hierarchy tree in the semantic relativity computation.Not only direct hierarchy relationships,but also non-direct hierarchy relationships and other typical semantic relationships are taken into account.Experimental results show that the proposed method can reduce the number of candidate item sets effectively and improve the efficiency of association rules mining.
文摘This paper presents the conservation law of Einstein's General Relativity, in whichthe continuity equation of matter and gravitational field is implicitly derived from theequation of motion of matter. Although the obtained energy-momentum tensor is thesame as the Landau- Lifshitz pseudotensor. the physical and conceptual foundation aredifferent. Two alternative methods to obtain the gravitational radiation are proposed inthis paper as well The radiation will be derived from the equation of motion of matterand geodesic equation separately.
文摘Sapir-Whorf Hypothesis is controversial, but the Linguistic Relativity is universally accepted by scholars. Through ana lyzing the causes of the mistakes that students often make during English learning and the relationship among thoughts, cultures and languages, this paper argues that language can influence people's thoughts and people's thoughts can influence the acquisi tion of a second language.
