This paper investigates a sliding-mode model predictive control （MPC） algorithm with auxiliary contractive sliding vector constraint for constrained nonlinear discrete-time systems. By adding contractive constraint ...This paper investigates a sliding-mode model predictive control （MPC） algorithm with auxiliary contractive sliding vector constraint for constrained nonlinear discrete-time systems. By adding contractive constraint into the optimization problem in regular sliding-mode MPC algorithm, the value of the sliding vector is decreased to zero asymptotically, which means that the system state is driven into a vicinity of sliding surface with a certain width. Then, the system state moves along the sliding surface to the equilibrium point within the vicinity. By applying the proposed algorithm, the stability of the closed-loop system is guaranteed. A numerical example of a continuous stirred tank reactor （CSTR） system is given to verify the feasibility and effectiveness of the proposed method.展开更多
The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between node...The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between nodes with tasks to he executed and nodes that may be able to execute those tasks. In contract net protocol,once negotiation successes,tbe task execution is assumed to success. However,in real world,even though a task is awarded to successfully bidding nodes,it may be delayed. Such delay may badly propagate in whole system. Here,we introduce real-time constraints into contract net protocol to manage task execution for avoiding the, task's delay,or even though being delayed,the railure cannot propagate to whole system. In this paper,we first present a real-time contract net protocol which is an extension of contract net protocol with real-time constraints for distributed computing. Our proposition extends the basic negotiation protocol to negotiation and controlling execution or task. The controlling process is based on task deadline time,we also present an extension of the internode language of contract net protocol specification with real-time constraints.展开更多
The aim of this work is to show that the currently widely accepted geometrical model of space and time based on the works of Einstein and Minkowski is not unique. The work presents an alternative geometrical model of ...The aim of this work is to show that the currently widely accepted geometrical model of space and time based on the works of Einstein and Minkowski is not unique. The work presents an alternative geometrical model of space and time, a model which, unlike the current one, is based solely on Euclidean geometry. In the new model, the pseudo-Euclidean spacetime is replaced with a specific subset of four-dimensional Euclidean space. The work shows that four-dimensional Euclidean space allows explanation of known relativistic effects that are now explained in pseudo-Euclidean spacetime by Einstein’s Special Theory of Relativity (STR). It also shows simple geometric-kinematical nature of known relativistic phenomena and among others explains why we cannot travel backward in time. The new solution is named the Euclidean Model of Space and Time (EMST).展开更多
In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved ...In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved that space and time are de-pendent and must be treated inseparably. Minkowski adopted a four-dimensional space-time frame and indirectly revealed the dependency of space and time by adding a constraint for an event interval. Since space and time are inseparable, a three-dimensional space-time frame can be constructed by embedding time into space to directly show the interdependency of space and time. The formula for time dilation, length contraction, and the Lorenz transformation can be derived from graphs utilizing this new frame. The proposed three-dimensional space-time frame is an alternate frame that can be used to describe motions of objects, and it may improve teaching and learning Special Relativity and provide additional insights into space and time.展开更多
Claims over contracts in the building,engineering and construction industry are become common issues in business today.The text aims at presenting the key concepts of construction claim,and construction claim manageme...Claims over contracts in the building,engineering and construction industry are become common issues in business today.The text aims at presenting the key concepts of construction claim,and construction claim management,focusing on the common classifica tion.In addition,it introduces some measures trying to prevent the event of claim.The result from the text can help the contractors im prove their weaknesses and maintain their strengths of their claim management process.Meanwhile,it also gives some measures for owner to prevent the contractor's claim.展开更多
In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and...In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and therefore must not be treated separately. Minkowski adopted four-dimensional space-time frames (4-d s-t frames), which indirectly revealed the dependency of space and time with the addition of a constraint for an event interval. We are not able to visualize 4-d s-t frames. Since space and time are inseparable, three-dimensional space-time frames (3-d s-t frames) can be constructed by embedding time into space to directly show the interdependency of space and time. Time contraction and length contraction can also be depicted graphically using 3-d s-t frames. We have much better understanding reality of space and time in 3-d s-t frames. This will lead to Contextual Reality for better understanding the universe.展开更多
Analysis of rotorcraft dynamics requires solution of the rotor induced flow field.Often,the appropriate model to be used for induced flow is nonlinear potential flow theory（which is the basis of vortex-lattice method...Analysis of rotorcraft dynamics requires solution of the rotor induced flow field.Often,the appropriate model to be used for induced flow is nonlinear potential flow theory（which is the basis of vortex-lattice methods）.These nonlinear potential flow equations sometimes must be solved in real time––such as for real-time flight simulation,when observers are needed for controllers,or in preliminary design computations.In this paper,the major effects of nonlinearities on induced flow are studied for lifting rotors in low-speed flight and hover.The approach is to use a nonlinear statespace model of the induced flow based on a Galerkin treatment of the potential flow equations.展开更多
针对传统基于到达时间差(Time Difference of Arrival,TDOA)定位方法存在的数值结果不确定性导致的定位误差问题,提出了一种采用双向收缩优化的TDOA区间定位算法。该算法在区间前向收缩阶段利用坐标系旋转解决了基站布型导致的定位失败...针对传统基于到达时间差(Time Difference of Arrival,TDOA)定位方法存在的数值结果不确定性导致的定位误差问题,提出了一种采用双向收缩优化的TDOA区间定位算法。该算法在区间前向收缩阶段利用坐标系旋转解决了基站布型导致的定位失败问题,并巧妙地将时差测量转换为双曲线区间,利用二分法将双曲线区间离散成矩形集,并进行区间交叠运算缩小初始定位区间;在区间后向收缩阶段,利用初始定位区间反向收缩双曲线区间。由该算法最终可以得到收敛的区间定位结果。仿真结果表明,优化后的算法在不影响定位精度并且达到了克拉美罗下界的同时,定位结果的面积由40.10 m^(2)缩小到22.20 m^(2),降低了44.6%,置信度始终保持在99.3%以上。展开更多
基金supported by Fundamental Research Funds for the Central Universities(Nos. CDJXS10170008 and CDJXS10171101)
文摘This paper investigates a sliding-mode model predictive control （MPC） algorithm with auxiliary contractive sliding vector constraint for constrained nonlinear discrete-time systems. By adding contractive constraint into the optimization problem in regular sliding-mode MPC algorithm, the value of the sliding vector is decreased to zero asymptotically, which means that the system state is driven into a vicinity of sliding surface with a certain width. Then, the system state moves along the sliding surface to the equilibrium point within the vicinity. By applying the proposed algorithm, the stability of the closed-loop system is guaranteed. A numerical example of a continuous stirred tank reactor （CSTR） system is given to verify the feasibility and effectiveness of the proposed method.
文摘The contract net protocol has developed to specify problem solving communication for nodes in a distributed problem solving. Task distribution is affected by a negotiation process,a discussion carried on between nodes with tasks to he executed and nodes that may be able to execute those tasks. In contract net protocol,once negotiation successes,tbe task execution is assumed to success. However,in real world,even though a task is awarded to successfully bidding nodes,it may be delayed. Such delay may badly propagate in whole system. Here,we introduce real-time constraints into contract net protocol to manage task execution for avoiding the, task's delay,or even though being delayed,the railure cannot propagate to whole system. In this paper,we first present a real-time contract net protocol which is an extension of contract net protocol with real-time constraints for distributed computing. Our proposition extends the basic negotiation protocol to negotiation and controlling execution or task. The controlling process is based on task deadline time,we also present an extension of the internode language of contract net protocol specification with real-time constraints.
文摘The aim of this work is to show that the currently widely accepted geometrical model of space and time based on the works of Einstein and Minkowski is not unique. The work presents an alternative geometrical model of space and time, a model which, unlike the current one, is based solely on Euclidean geometry. In the new model, the pseudo-Euclidean spacetime is replaced with a specific subset of four-dimensional Euclidean space. The work shows that four-dimensional Euclidean space allows explanation of known relativistic effects that are now explained in pseudo-Euclidean spacetime by Einstein’s Special Theory of Relativity (STR). It also shows simple geometric-kinematical nature of known relativistic phenomena and among others explains why we cannot travel backward in time. The new solution is named the Euclidean Model of Space and Time (EMST).
文摘In Newton’s classical physics, space and time are treated as absolute quantities. Space and time are treated as independent quantities and can be discussed sepa-rately. With his theory of relativity, Einstein proved that space and time are de-pendent and must be treated inseparably. Minkowski adopted a four-dimensional space-time frame and indirectly revealed the dependency of space and time by adding a constraint for an event interval. Since space and time are inseparable, a three-dimensional space-time frame can be constructed by embedding time into space to directly show the interdependency of space and time. The formula for time dilation, length contraction, and the Lorenz transformation can be derived from graphs utilizing this new frame. The proposed three-dimensional space-time frame is an alternate frame that can be used to describe motions of objects, and it may improve teaching and learning Special Relativity and provide additional insights into space and time.
文摘Claims over contracts in the building,engineering and construction industry are become common issues in business today.The text aims at presenting the key concepts of construction claim,and construction claim management,focusing on the common classifica tion.In addition,it introduces some measures trying to prevent the event of claim.The result from the text can help the contractors im prove their weaknesses and maintain their strengths of their claim management process.Meanwhile,it also gives some measures for owner to prevent the contractor's claim.
文摘In Newton’s classical physics, space and time are treated as absolute, independent quantities and can be discussed separately. In Special Relativity, Einstein proved that space and time are relative and dependent and therefore must not be treated separately. Minkowski adopted four-dimensional space-time frames (4-d s-t frames), which indirectly revealed the dependency of space and time with the addition of a constraint for an event interval. We are not able to visualize 4-d s-t frames. Since space and time are inseparable, three-dimensional space-time frames (3-d s-t frames) can be constructed by embedding time into space to directly show the interdependency of space and time. Time contraction and length contraction can also be depicted graphically using 3-d s-t frames. We have much better understanding reality of space and time in 3-d s-t frames. This will lead to Contextual Reality for better understanding the universe.
基金co-supported by the National Natural Science Foundation of China(No.51375104)the Heilongjiang Province Funds for Distinguished Young Scientists(No.JC201405)+1 种基金the China Postdoctoral Science Foundation(No.2015M581433)the Postdoctoral Science Foundation of Heilongjiang Province(No.LBH-Z15038)
文摘Analysis of rotorcraft dynamics requires solution of the rotor induced flow field.Often,the appropriate model to be used for induced flow is nonlinear potential flow theory（which is the basis of vortex-lattice methods）.These nonlinear potential flow equations sometimes must be solved in real time––such as for real-time flight simulation,when observers are needed for controllers,or in preliminary design computations.In this paper,the major effects of nonlinearities on induced flow are studied for lifting rotors in low-speed flight and hover.The approach is to use a nonlinear statespace model of the induced flow based on a Galerkin treatment of the potential flow equations.
