On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent me...On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth.展开更多
Confucius attaches great importance to the relationship between benevolence, wisdom and courage. Benevolence is the core of Confucius＇s moral principle, which reflects the principle of Confucius values; Wisdom is the...Confucius attaches great importance to the relationship between benevolence, wisdom and courage. Benevolence is the core of Confucius＇s moral principle, which reflects the principle of Confucius values; Wisdom is the recognition of the principle of benevolence and other values; Courage is the inner belief to achieve benevolence. Putnam rejected the dichotomy, of facts and value, he thought value problem also have cognitive meaning. This theory maintenance the relationship between benevolence, wisdom and courage is reasonable. To discuss the relationship between benevolence, wisdom and courage in the context of Putnam＇s value theory will help us to achieve the benevolence thought modernization.展开更多
In the research of path planning for manipulators with many DOF, generally there is a problem in most traditional methods, which is that their computational cost (time and memory space) increases exponentially as DOF ...In the research of path planning for manipulators with many DOF, generally there is a problem in most traditional methods, which is that their computational cost (time and memory space) increases exponentially as DOF or resolution of the discrete configuration space increases. So this paper presents the collision-free trajectory planning for the space robot to capture a target based on the wavelet interpolation algorithm. We made wavelet sample on the desired trajectory of the manipulator’s end-effector to do trajectory planning by use of the proposed wavelet interpolation formula, and then derived joint vectors from the trajectory information of the end-effector based on the fixed-attitude-restrained generalized Jacobian matrix of multi-arm coordinated motion, so as to control the manipulator to capture a static body along the desired collision-free trajectory. The method overcomes the shortcomings of the typical methods, and the desired trajectory of the end-effector can be any kind of complex nonlinear curve. The algorithm is simple and highly effective and the real trajectory is close to the desired trajectory. In simulation, the planar dual-arm three DOF space robot is used to demonstrate the proposed method, and it shows that the algorithm is feasible.展开更多
Lexical chunks are multiword lexical phenomena that exist somewhere between the traditional poles of lexicon and syntax, conventionalized form/function composites that occur more frequently and have more idiomatically...Lexical chunks are multiword lexical phenomena that exist somewhere between the traditional poles of lexicon and syntax, conventionalized form/function composites that occur more frequently and have more idiomatically determined meaning than language that is put together each time. Lexical chunks theory supports the development of syntactic rules, helps learners to achieve idiomaticity and appropriateness of business expressions, and benefits successful business communication. Through the study of lexical chunks, the major findings are that possibility of lexical chunks in business English correspondences is relatively high, and among factors influencing discourse coherence, lexical chunks are the main point that has already attracted much attention of users. Based on the study, some pedagogical suggestions are provided in business English correspondence writing class.展开更多
基金Project(2013CB036004) supported by the National Basic Research Program of ChinaProjects(51178468,51378510) supported by the National Natural Science Foundation of ChinaProject(CX2013B077) supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘On the basis of upper bound theorem, non-associated flow rule and non-linear failure criterion were considered together.The modified shear strength parameters of materials were obtained with the help of the tangent method. Employing the virtual power principle and strength reduction technique, the effects of dilatancy of materials, non-linear failure criterion, pore water pressure,surface loads and buried depth, on the stability of shallow tunnel were studied. In order to validate the effectiveness of the proposed approach, the solutions in the present work agree well with the existing results when the non-associated flow rule is reduced to the associated flow rule and the non-linear failure criterion is degenerated to the linear failure criterion. Compared with dilatancy of materials, the non-linear failure criterion exerts greater impact on the stability of shallow tunnels. The safety factor of shallow tunnels decreases and the failure surface expands outward when the dilatancy coefficient decreases. While the increase of nonlinear coefficient, the pore water pressure coefficient, the surface load and the buried depth results in the small safety factor. Therefore, the dilatancy as well as non-linear failure criterion should be taken into account in the design of shallow tunnel supporting structure. The supporting structure must be reinforced promptly to prevent potential mud from gushing or collapse accident in the areas with abundant pore water, large surface load or buried depth.
文摘Confucius attaches great importance to the relationship between benevolence, wisdom and courage. Benevolence is the core of Confucius＇s moral principle, which reflects the principle of Confucius values; Wisdom is the recognition of the principle of benevolence and other values; Courage is the inner belief to achieve benevolence. Putnam rejected the dichotomy, of facts and value, he thought value problem also have cognitive meaning. This theory maintenance the relationship between benevolence, wisdom and courage is reasonable. To discuss the relationship between benevolence, wisdom and courage in the context of Putnam＇s value theory will help us to achieve the benevolence thought modernization.
文摘In the research of path planning for manipulators with many DOF, generally there is a problem in most traditional methods, which is that their computational cost (time and memory space) increases exponentially as DOF or resolution of the discrete configuration space increases. So this paper presents the collision-free trajectory planning for the space robot to capture a target based on the wavelet interpolation algorithm. We made wavelet sample on the desired trajectory of the manipulator’s end-effector to do trajectory planning by use of the proposed wavelet interpolation formula, and then derived joint vectors from the trajectory information of the end-effector based on the fixed-attitude-restrained generalized Jacobian matrix of multi-arm coordinated motion, so as to control the manipulator to capture a static body along the desired collision-free trajectory. The method overcomes the shortcomings of the typical methods, and the desired trajectory of the end-effector can be any kind of complex nonlinear curve. The algorithm is simple and highly effective and the real trajectory is close to the desired trajectory. In simulation, the planar dual-arm three DOF space robot is used to demonstrate the proposed method, and it shows that the algorithm is feasible.
文摘Lexical chunks are multiword lexical phenomena that exist somewhere between the traditional poles of lexicon and syntax, conventionalized form/function composites that occur more frequently and have more idiomatically determined meaning than language that is put together each time. Lexical chunks theory supports the development of syntactic rules, helps learners to achieve idiomaticity and appropriateness of business expressions, and benefits successful business communication. Through the study of lexical chunks, the major findings are that possibility of lexical chunks in business English correspondences is relatively high, and among factors influencing discourse coherence, lexical chunks are the main point that has already attracted much attention of users. Based on the study, some pedagogical suggestions are provided in business English correspondence writing class.
