空间信息包含方向、拓扑、形状、距离等多种关系.定性空间关系表示与推理是人工智能的重要研究子域,在空间信息系统、机器人导航、自然语言理解、智能交通等领域有着广泛的应用.以往研究多面向静态空间对象,侧重单一空间关系,对不同空...空间信息包含方向、拓扑、形状、距离等多种关系.定性空间关系表示与推理是人工智能的重要研究子域,在空间信息系统、机器人导航、自然语言理解、智能交通等领域有着广泛的应用.以往研究多面向静态空间对象,侧重单一空间关系,对不同空间关系间的约束研究不够深入,难以基于一种空间关系对另一种空间关系的演变做出有效推理.针对移动空间对象之间定性方向关系与定性距离变化的结合推理问题,利用射线与圆之间位置关系的组合来描述2个空间对象之间的相对移动方向;分别研究并证明该位置关系的组合对定性距离变化的约束作用、该位置关系的组合与粒度为4的有向点方向代数(oriented point algebra with granularity of 4, OPRA4)间的对应关系,进而建立起OPRA4方向关系与定性距离变化之间的内在联系;提出一种基于基本OPRA4方向关系推理定性距离变化的方法,并结合交通领域中的连续k近邻查询实例说明该方法的正确性和有效性.展开更多
Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclos...Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies. We focused our attention on the case of mining away from a gully. We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations. The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability. These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.展开更多
In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicop...In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicopter＇s velocity, safe distances, and safe sphere when it runs across the obstacle consisting of telegraph poles and electricaJ wire.展开更多
In this paper,the distance-sability of nonlinear discrete system is investigated by means of the Gauss-Seidel iteration method.Some algebric criteria of the distance-stability are ob-tained.Construction of Lyapunov fu...In this paper,the distance-sability of nonlinear discrete system is investigated by means of the Gauss-Seidel iteration method.Some algebric criteria of the distance-stability are ob-tained.Construction of Lyapunov function is avoided.展开更多
In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model （COVM）, whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also de...In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model （COVM）, whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also depends on the velocity difference with preceding vehicle. Simulation results show that COVM is an improvement over the previous ones theoretically. Then, the stability condition of the model is obtained by the linear stability analysis, which has shown that the model could obtain a bigger stable region than previous models in the phase diagram. Through the nonlinear analysis, the Burgers, Korteweg-de Vries （KdV） and modified KdV （mKdV） equations are derived for the triangular shock wave, the soliton wave, and the kink-antikink soliton wave. At the same time, numerical simulations are also carried out to show that the model could simulate these density waves.展开更多
With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Al...With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Although these vortices are approximate, they can reflect the real properties of self-similar optical beam during a short-term propagation. Existence of these autonomous vortices require delicate balances between the system parameters such as diffraction, nonlinearity, gain, and external potential. We are concerned with some special but interesting situations, and discussing the changes of the height, width, energy, and central position of the vortices as the increase of propagation distance. Moreover, we are also interested in the azimuthal modulational instability of the system, and comparing our prediction for the modulational instability growth rates to numerical results.展开更多
We introduce several KAM theorems for infinite-dimensional Hamiltonian with short range and discuss the relationship between spectra of linearized operator and invariant tori.Especially,we introduce a KAM theorem by Y...We introduce several KAM theorems for infinite-dimensional Hamiltonian with short range and discuss the relationship between spectra of linearized operator and invariant tori.Especially,we introduce a KAM theorem by Yuan published in CMP(2002),which shows that there are rich KAM tori for a class of Hamiltonian with short range and with linearized operator of pure point spectra.We also present several open problems.展开更多
文摘空间信息包含方向、拓扑、形状、距离等多种关系.定性空间关系表示与推理是人工智能的重要研究子域,在空间信息系统、机器人导航、自然语言理解、智能交通等领域有着广泛的应用.以往研究多面向静态空间对象,侧重单一空间关系,对不同空间关系间的约束研究不够深入,难以基于一种空间关系对另一种空间关系的演变做出有效推理.针对移动空间对象之间定性方向关系与定性距离变化的结合推理问题,利用射线与圆之间位置关系的组合来描述2个空间对象之间的相对移动方向;分别研究并证明该位置关系的组合对定性距离变化的约束作用、该位置关系的组合与粒度为4的有向点方向代数(oriented point algebra with granularity of 4, OPRA4)间的对应关系,进而建立起OPRA4方向关系与定性距离变化之间的内在联系;提出一种基于基本OPRA4方向关系推理定性距离变化的方法,并结合交通领域中的连续k近邻查询实例说明该方法的正确性和有效性.
基金Financial support for this work, provided by the Research Fund of the Fundamental Research Funds for the Central Universities of China University of Mining & Technology (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Mine Safety (No. SKLCRSM08X2)+1 种基金the Jiangsu "333" High Qualified Talents, the National Natural Science Foundation of China (Nos. 50904063 and 51004101)the Scientific Research Foundation of China University of Mining & Technology (Nos. 2008A003 and 2009A001)
文摘Underground pressure is abnormal during mining of shallow coal seams under gullies. We studied gully slope movements, subject to underground mining, with physical simulation and theoretical analysis. The rules disclose that the slope rock slides horizontally in response to mining in the direction of gullies and rotates reversely with the appearance of a polygon block in mining away from gullies. We focused our attention on the case of mining away from a gully. We built a mechanical model in terms of a polygon block hinged structure and investigated the variation of horizontal thrust and shear force at the hinged point in relation to the rotation angle under different fragmentations. The Sliding-Rotation instability conditions of the polygon block hinged structure are presented based on the analyses of sliding instability and rotation instability. These results can serve as a theoretical guide for roof control during mining away from gullies in a coalfield defined by gullies.
基金Supported by the State Key Basic Research Program of China under Grant No.2011CB707002
文摘In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicopter＇s velocity, safe distances, and safe sphere when it runs across the obstacle consisting of telegraph poles and electricaJ wire.
基金The project is supported by Henan Province Natural Science Fund
文摘In this paper,the distance-sability of nonlinear discrete system is investigated by means of the Gauss-Seidel iteration method.Some algebric criteria of the distance-stability are ob-tained.Construction of Lyapunov function is avoided.
基金Supported by the National Natural Science Foundation of China under Grant Nos.71071013,71001004,and 71071012Foundation of Beijing Jiaotong University under Grant No.2009JBZ012-2
文摘In this paper, we present a new ear-following model, i.e. comprehensive optimal velocity model （COVM）, whose optimal velocity function not only depends on the following distance of the preceding vehicle, but also depends on the velocity difference with preceding vehicle. Simulation results show that COVM is an improvement over the previous ones theoretically. Then, the stability condition of the model is obtained by the linear stability analysis, which has shown that the model could obtain a bigger stable region than previous models in the phase diagram. Through the nonlinear analysis, the Burgers, Korteweg-de Vries （KdV） and modified KdV （mKdV） equations are derived for the triangular shock wave, the soliton wave, and the kink-antikink soliton wave. At the same time, numerical simulations are also carried out to show that the model could simulate these density waves.
文摘With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Although these vortices are approximate, they can reflect the real properties of self-similar optical beam during a short-term propagation. Existence of these autonomous vortices require delicate balances between the system parameters such as diffraction, nonlinearity, gain, and external potential. We are concerned with some special but interesting situations, and discussing the changes of the height, width, energy, and central position of the vortices as the increase of propagation distance. Moreover, we are also interested in the azimuthal modulational instability of the system, and comparing our prediction for the modulational instability growth rates to numerical results.
基金supported by National Natural Science Foundation of China (Grant Nos.11271076 and 11121101)the National Basic Research Program of China (973 Program) (Grant No.2010CB327900)
文摘We introduce several KAM theorems for infinite-dimensional Hamiltonian with short range and discuss the relationship between spectra of linearized operator and invariant tori.Especially,we introduce a KAM theorem by Yuan published in CMP(2002),which shows that there are rich KAM tori for a class of Hamiltonian with short range and with linearized operator of pure point spectra.We also present several open problems.
