Two constraint violation stabilization methods are presented to solve the Euler Lagrange equations of motion of a multibody system with nonholonomic constraints. Compared to the previous works, the newly devised metho...Two constraint violation stabilization methods are presented to solve the Euler Lagrange equations of motion of a multibody system with nonholonomic constraints. Compared to the previous works, the newly devised methods can deal with more complicated problems such as those with nonholonomic constraints or redundant constraints, and save the computation time. Finally a numerical simulation of a multibody system is conducted by using the methods given in this paper.展开更多
A new automatic constraint violation stabilization method for numerical integration of Euler_Lagrange equations of motion in dynamics of multibody systems is presented. The parameters α,β used in the traditional con...A new automatic constraint violation stabilization method for numerical integration of Euler_Lagrange equations of motion in dynamics of multibody systems is presented. The parameters α,β used in the traditional constraint violation stabilization method are determined according to the integration time step size and Taylor expansion method automatically. The direct integration method, the traditional constraint violation stabilization method and the new method presented in this paper are compared finally.展开更多
Aiming at the problem that current geographical information systems(GIS)usually does not maintain semantic and user-defined constraints out of three consistency-constrains(third refers to topology constraint),this res...Aiming at the problem that current geographical information systems(GIS)usually does not maintain semantic and user-defined constraints out of three consistency-constrains(third refers to topology constraint),this research focuses on building an efficient spatial data management system using two constraint violation detection methods.An algorithm for constraint violation detection has been derived to maintain the error-free up-to-date spatial database.Results indicate that the developed constraint violation detection(CVD)system is more efficient compared with conventional systems.展开更多
Projected Runge-Kutta （R-K） methods for constrained Hamiltonian systems are proposed. Dynamic equations of the systems, which are index-3 differential-algebraic equations （DAEs） in the Heisenberg form, are establi...Projected Runge-Kutta （R-K） methods for constrained Hamiltonian systems are proposed. Dynamic equations of the systems, which are index-3 differential-algebraic equations （DAEs） in the Heisenberg form, are established under the framework of Lagrangian multipliers. R-K methods combined with the technique of projections are then used to solve the DAEs. The basic idea of projections is to eliminate the constraint violations at the position, velocity, and acceleration levels, and to preserve the total energy of constrained Hamiltonian systems by correcting variables of the position, velocity, acceleration, and energy. Numerical results confirm the validity and show the high precision of the proposed method in preserving three levels of constraints and total energy compared with results reported in the literature.展开更多
This paper proposes a data-and model-driven col-laborative resource scheduling method to maximize the spec-tral efficiency(SE)of cell-free(CF)downlink multiuser multiple-input multiple-output(MIMO)systems,subject to d...This paper proposes a data-and model-driven col-laborative resource scheduling method to maximize the spec-tral efficiency(SE)of cell-free(CF)downlink multiuser multiple-input multiple-output(MIMO)systems,subject to delay violation probability and power constraints.The method integrates the weighted minimum mean square error(WMMSE)algorithm within the safety reinforcement learn-ing(Safety-RL)framework.The original optimization problem is decomposed into two coupled subproblems.The Safety-RL algorithm leverages state features to determine user priority weights and allocate bandwidths,while the WMMSE algorithm calculates the precoding matrix and fur-ther schedules resources based on user priority weights to obtain the reward and costs of Safety-RL.Considering dy-namic user access in CF systems,a distributed algorithm with user scalability is also proposed.Simulation results demonstrate that the proposed approach improves the SE while meeting the different delay violation probability con-straints of users.Furthermore,the distributed algorithm of-fers comparable performance to the fully centralized method while considerably reducing model training overhead,par-ticularly as users dynamically access the system.展开更多
In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation（LIV）. As the most energetic explosions in the Universe, gamma-ray bursts（GRBs） provide an effect way to pr...In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation（LIV）. As the most energetic explosions in the Universe, gamma-ray bursts（GRBs） provide an effect way to probe quantum gravity effects. In this paper, we use the continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale MQG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to low energy ones. Based on the fact that the LIV-induced time delay cannot be longer than the duration of a GRB,we present the most conservative estimate of the quantum gravity energy scales from 20 short GRBs. The strictest constraint, M_（QG） 〉 5.05 × 10^（14） GeV in the linearly corrected case, is from GRB 140622 A. Our constraint on MQG,although not as tight as previous results, is the safest and most reliable so far.展开更多
In this paper,we consider online convex optimization(OCO)with time-varying loss and constraint functions.Specifically,the decision-maker chooses sequential decisions based only on past information;meantime,the loss an...In this paper,we consider online convex optimization(OCO)with time-varying loss and constraint functions.Specifically,the decision-maker chooses sequential decisions based only on past information;meantime,the loss and constraint functions are revealed over time.We first develop a class of model-based augmented Lagrangian methods(MALM)for time-varying functional constrained OCO(without feedback delay).Under standard assumptions,we establish sublinear regret and sublinear constraint violation of MALM.Furthermore,we extend MALM to deal with time-varying functional constrained OCO with delayed feedback,in which the feedback information of loss and constraint functions is revealed to decision-maker with delays.Without additional assumptions,we also establish sublinear regret and sublinear constraint violation for the delayed version of MALM.Finally,numerical results for several examples of constrained OCO including online network resource allocation,online logistic regression and online quadratically constrained quadratical program are presented to demonstrate the efficiency of the proposed algorithms.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 19902006).
文摘Two constraint violation stabilization methods are presented to solve the Euler Lagrange equations of motion of a multibody system with nonholonomic constraints. Compared to the previous works, the newly devised methods can deal with more complicated problems such as those with nonholonomic constraints or redundant constraints, and save the computation time. Finally a numerical simulation of a multibody system is conducted by using the methods given in this paper.
文摘A new automatic constraint violation stabilization method for numerical integration of Euler_Lagrange equations of motion in dynamics of multibody systems is presented. The parameters α,β used in the traditional constraint violation stabilization method are determined according to the integration time step size and Taylor expansion method automatically. The direct integration method, the traditional constraint violation stabilization method and the new method presented in this paper are compared finally.
文摘Aiming at the problem that current geographical information systems(GIS)usually does not maintain semantic and user-defined constraints out of three consistency-constrains(third refers to topology constraint),this research focuses on building an efficient spatial data management system using two constraint violation detection methods.An algorithm for constraint violation detection has been derived to maintain the error-free up-to-date spatial database.Results indicate that the developed constraint violation detection(CVD)system is more efficient compared with conventional systems.
基金Project supported by the National Natural Science Foundation of China(No.11432010)the Doctoral Program Foundation of Education Ministry of China(No.20126102110023)+2 种基金the 111Project of China(No.B07050)the Fundamental Research Funds for the Central Universities(No.310201401JCQ01001)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(No.CX201517)
文摘Projected Runge-Kutta （R-K） methods for constrained Hamiltonian systems are proposed. Dynamic equations of the systems, which are index-3 differential-algebraic equations （DAEs） in the Heisenberg form, are established under the framework of Lagrangian multipliers. R-K methods combined with the technique of projections are then used to solve the DAEs. The basic idea of projections is to eliminate the constraint violations at the position, velocity, and acceleration levels, and to preserve the total energy of constrained Hamiltonian systems by correcting variables of the position, velocity, acceleration, and energy. Numerical results confirm the validity and show the high precision of the proposed method in preserving three levels of constraints and total energy compared with results reported in the literature.
基金The National Natural Science Foundation of China (No. 62271140, 62225107)the Natural Science Foundation of Jiangsu Province (No. BK20240174)+1 种基金the Fundamental Research Funds for the Central Universities (No. 2242022k60002)the Fund of Jiangsu Provincial Scientific Research Center of Applied Mathematics (No. BK20233002)。
文摘This paper proposes a data-and model-driven col-laborative resource scheduling method to maximize the spec-tral efficiency(SE)of cell-free(CF)downlink multiuser multiple-input multiple-output(MIMO)systems,subject to delay violation probability and power constraints.The method integrates the weighted minimum mean square error(WMMSE)algorithm within the safety reinforcement learn-ing(Safety-RL)framework.The original optimization problem is decomposed into two coupled subproblems.The Safety-RL algorithm leverages state features to determine user priority weights and allocate bandwidths,while the WMMSE algorithm calculates the precoding matrix and fur-ther schedules resources based on user priority weights to obtain the reward and costs of Safety-RL.Considering dy-namic user access in CF systems,a distributed algorithm with user scalability is also proposed.Simulation results demonstrate that the proposed approach improves the SE while meeting the different delay violation probability con-straints of users.Furthermore,the distributed algorithm of-fers comparable performance to the fully centralized method while considerably reducing model training overhead,par-ticularly as users dynamically access the system.
基金Supported by National Natural Science Foundation of China(11375203,11305181,11322545,11335012)Knowledge Innovation Program of The Chinese Academy of Sciences
文摘In some quantum gravity theories, a foamy structure of space-time may lead to Lorentz invariance violation（LIV）. As the most energetic explosions in the Universe, gamma-ray bursts（GRBs） provide an effect way to probe quantum gravity effects. In this paper, we use the continuous spectra of 20 short GRBs detected by the Swift satellite to give a conservative lower limit of quantum gravity energy scale MQG. Due to the LIV effect, photons with different energy have different velocities. This will lead to the delayed arrival of high energy photons relative to low energy ones. Based on the fact that the LIV-induced time delay cannot be longer than the duration of a GRB,we present the most conservative estimate of the quantum gravity energy scales from 20 short GRBs. The strictest constraint, M_（QG） 〉 5.05 × 10^（14） GeV in the linearly corrected case, is from GRB 140622 A. Our constraint on MQG,although not as tight as previous results, is the safest and most reliable so far.
基金supported in part by the National Key R&D Program of China(No.2022YFA1004000)the National Natural Science Foundation of China(Nos.11971089 and 12271076).
文摘In this paper,we consider online convex optimization(OCO)with time-varying loss and constraint functions.Specifically,the decision-maker chooses sequential decisions based only on past information;meantime,the loss and constraint functions are revealed over time.We first develop a class of model-based augmented Lagrangian methods(MALM)for time-varying functional constrained OCO(without feedback delay).Under standard assumptions,we establish sublinear regret and sublinear constraint violation of MALM.Furthermore,we extend MALM to deal with time-varying functional constrained OCO with delayed feedback,in which the feedback information of loss and constraint functions is revealed to decision-maker with delays.Without additional assumptions,we also establish sublinear regret and sublinear constraint violation for the delayed version of MALM.Finally,numerical results for several examples of constrained OCO including online network resource allocation,online logistic regression and online quadratically constrained quadratical program are presented to demonstrate the efficiency of the proposed algorithms.
