A discrete event system is a dynamical system whose state evolves in time by the occurrence of events at possibly irregular time intervals. Timed Petri nets are a graphical and mathematical modeling tool applicable to...A discrete event system is a dynamical system whose state evolves in time by the occurrence of events at possibly irregular time intervals. Timed Petri nets are a graphical and mathematical modeling tool applicable to discrete event systems in order to represent its states evolution where the timing at which the state changes is taken into consideration. One of the most important performance issues to be considered in a discrete event system is its stability. Lyapunov theory provides the required tools needed to aboard the stability and stabilization problems for discrete event systems modeled with timed Petri nets whose mathematical model is given in terms of difference equations. By proving stability one guarantees a bound on the discrete event systems state dynamics. When the system is unstable, a sufficient condition to stabilize the system is given. It is shown that it is possible to restrict the discrete event systems state space in such a way that boundedness is achieved. However, the restriction is not numerically precisely known. This inconvenience is overcome by considering a specific recurrence equation, in the max-plus algebra, which is assigned to the timed Petri net graphical model.展开更多
As one novel reinforcement used in magnesium composite,nano-layered flaky ternary MAX particle exhibits interesting anisotropic ceramic and metal properties.In order to accurately simulate the mechanical properties an...As one novel reinforcement used in magnesium composite,nano-layered flaky ternary MAX particle exhibits interesting anisotropic ceramic and metal properties.In order to accurately simulate the mechanical properties and damage behavior of MAX particle reinforced magnesium composite,we developed one finite element(FE)model based on 2D and 3D microstructural observations of 10 vol.%Ti_(2)AlC-AZ91D composite.To improve the accuracy,matrix ductile damage,particle internal delamination deformation behaviors,and particle-matrix interfacial behaviors were respectively introduced into this model.The visual deformation processes of crack generation and propagation were carefully presented and discussed.The effects of interfacial strength and particle orientation on material properties were systematically investigated.展开更多
In this paper, we establish the maximum norm estimates of the solutions of the finite volume element method （FVE） based on the P1 conforming element for the non-selfadjoint and indefinite elliptic problems.
合作是企业降低成本的有效策略之一,而合理测量与分配潜在好处是合作成功的关键。对具有竞争关系的合作者来说,其相对竞争力不应因合作而变化。本文首先基于数据包络分析(data envelopment analysis,DEA)与合作博弈论,构建成本DEA博弈,...合作是企业降低成本的有效策略之一,而合理测量与分配潜在好处是合作成功的关键。对具有竞争关系的合作者来说,其相对竞争力不应因合作而变化。本文首先基于数据包络分析(data envelopment analysis,DEA)与合作博弈论,构建成本DEA博弈,对决策单元(decision making unit, DMU)之间的合作行为进行定量刻画;然后针对该博弈的成本分配问题,提出平等竞争力方法(equal competitiveness method,ECM),最小化任意两个DMU(即合作参与人)在成本分配前后其相对竞争力变化的差异,使其尽可能保持原有的相对竞争力。基于行生成算法及字典式最小最大方法,ECM提供的成本分配方案满足唯一性、有效性、稳定性、对称性、虚拟参与人等性质。最后以3个DMU的算例和25家超市实际数据为例,通过对ECM分配结果、核、Shapley值以及核仁的对比,发现在成本分配后,ECM最能保持DMU的相对竞争力,为企业的合作决策及合作后的成本分配提供参考方案。展开更多
文摘A discrete event system is a dynamical system whose state evolves in time by the occurrence of events at possibly irregular time intervals. Timed Petri nets are a graphical and mathematical modeling tool applicable to discrete event systems in order to represent its states evolution where the timing at which the state changes is taken into consideration. One of the most important performance issues to be considered in a discrete event system is its stability. Lyapunov theory provides the required tools needed to aboard the stability and stabilization problems for discrete event systems modeled with timed Petri nets whose mathematical model is given in terms of difference equations. By proving stability one guarantees a bound on the discrete event systems state dynamics. When the system is unstable, a sufficient condition to stabilize the system is given. It is shown that it is possible to restrict the discrete event systems state space in such a way that boundedness is achieved. However, the restriction is not numerically precisely known. This inconvenience is overcome by considering a specific recurrence equation, in the max-plus algebra, which is assigned to the timed Petri net graphical model.
基金financed by the National Natural Science Foundation of China(no.52175284)the Science and Technology Research and Development Program of China State Railway Group Co.,Ltd.(K2022J003)+1 种基金the State Key Lab of Advanced Metals and Materials(2021-ZD08)Thanks to the technical support of BL13HB beamline in Shanghai Synchrotron Radiation Facility(SSRF).
文摘As one novel reinforcement used in magnesium composite,nano-layered flaky ternary MAX particle exhibits interesting anisotropic ceramic and metal properties.In order to accurately simulate the mechanical properties and damage behavior of MAX particle reinforced magnesium composite,we developed one finite element(FE)model based on 2D and 3D microstructural observations of 10 vol.%Ti_(2)AlC-AZ91D composite.To improve the accuracy,matrix ductile damage,particle internal delamination deformation behaviors,and particle-matrix interfacial behaviors were respectively introduced into this model.The visual deformation processes of crack generation and propagation were carefully presented and discussed.The effects of interfacial strength and particle orientation on material properties were systematically investigated.
基金The Major State Basic Research Program (19871051) of China and the NNSP (19972039) of China.
文摘In this paper, we establish the maximum norm estimates of the solutions of the finite volume element method （FVE） based on the P1 conforming element for the non-selfadjoint and indefinite elliptic problems.
文摘合作是企业降低成本的有效策略之一,而合理测量与分配潜在好处是合作成功的关键。对具有竞争关系的合作者来说,其相对竞争力不应因合作而变化。本文首先基于数据包络分析(data envelopment analysis,DEA)与合作博弈论,构建成本DEA博弈,对决策单元(decision making unit, DMU)之间的合作行为进行定量刻画;然后针对该博弈的成本分配问题,提出平等竞争力方法(equal competitiveness method,ECM),最小化任意两个DMU(即合作参与人)在成本分配前后其相对竞争力变化的差异,使其尽可能保持原有的相对竞争力。基于行生成算法及字典式最小最大方法,ECM提供的成本分配方案满足唯一性、有效性、稳定性、对称性、虚拟参与人等性质。最后以3个DMU的算例和25家超市实际数据为例,通过对ECM分配结果、核、Shapley值以及核仁的对比,发现在成本分配后,ECM最能保持DMU的相对竞争力,为企业的合作决策及合作后的成本分配提供参考方案。
