In surveying adjustment models,there is usually some uncertain additional information or prior information on parameters,which can constrain the parameters,and guarantee the uniqueness and stability of parameter solut...In surveying adjustment models,there is usually some uncertain additional information or prior information on parameters,which can constrain the parameters,and guarantee the uniqueness and stability of parameter solution.In this paper,we firstly use ellipsoidal sets to describe uncertainty,and establish a new adjustment model with ellipsoidal uncertainty.Furthermore,we give a new adjustment criterion based on minimization trace of an outer ellipsoid with two ellipsoid intersections,and analyze the propagation law of uncertainty.Correspondingly,we give a new algorithm for the adjustment model with ellipsoid uncertainty.Finally,we give three examples to test and verify the effectiveness of our algorithm,and illustrate the relation between our result and the weighted mixed estimation.展开更多
In density-based topological design, one expects that the final result consists of elements either black （solid material） or white （void）, without any grey areas. Moreover, one also expects that the optimal topolo...In density-based topological design, one expects that the final result consists of elements either black （solid material） or white （void）, without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multidisplacement constraints is proposed in this paper. In the proposed method, the whole optimization process is divided into two optimization adjustment phases and a phase transferring step. Firstly, an optimization model is built to deal with the varied displacement limits, design space adjustments, and reasonable relations between the element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve the optimization problem formulated in the first optimization adjustment phase, by starting with a small design space and advancing to a larger deign space. The design space adjustments are automatic when the design domain needs expansions, in which the convergence of the proposed method will not be affected. The final topology obtained by the proposed procedure in the first optimization phase, can approach to the vicinity of the optimum topology. Then, a heuristic algorithm is given to improve the efficiency and make the designed structural topology black/white in both the phase transferring step and the second optimization adjustment phase. And the optimum topology can finally be obtained by the second phase optimization adjustments. Two examples are presented to show that the topologies obtained by the proposed method are of very good 0/1 design distribution property, and the computational efficiency is enhanced by reducing the element number of the design structural finite model during two optimization adjustment phases. And the examples also show that this method is robust and practicable.展开更多
长江经济带是我国重要的水资源聚集区、水生态功能区,但是水环境污染和水资源消耗已成为其可持续发展的障碍。为推动长江经济带绿色高质量发展,本文旨在探究以水资源要素为中心考量长江经济带的资源分配如何影响绿色发展效率,同时厘清...长江经济带是我国重要的水资源聚集区、水生态功能区,但是水环境污染和水资源消耗已成为其可持续发展的障碍。为推动长江经济带绿色高质量发展,本文旨在探究以水资源要素为中心考量长江经济带的资源分配如何影响绿色发展效率,同时厘清长江经济带产业结构调整在其水资源要素影响绿色发展效率过程中发挥的重要作用。论文基于2003—2020年面板数据,运用超效率SBM(slack based measure)模型测算绿色发展效率,分析水资源总量、用水效率和水资源质量三重约束对长江经济带绿色发展效率的影响,并检验了产业结构调整的3个维度,即产业结构合理化、产业结构高级化以及产业结构软化的中介效应及其与水资源约束的交互效应。结果表明:1)水资源约束中用水效率对长江经济带绿色发展效率影响最大,表现为正向促进作用,促进力度表现出上游>中游>下游的特征;2)从中介效应来看,长江经济带全流域主要是产业结构软化在用水效率影响绿色经济发展时发挥了中介作用,分流域来看主要是产业结构高级化发挥了主要作用,产业结构高级化在上游地区水资源总量影响绿色发展效率时表现出了中介作用,在下游地区用水效率、水资源质量影响绿色发展效率过程中也表现出了中介效应;3)从交互效应来看,长江经济带全流域用水效率与产业结构高级化、产业结构软化之间均存在交互作用,此外还存在水量约束与产业结构合理化的交互效应,分区域来看,下游是交互效应作用范围最广的地区,用水效率与产业结构合理化、软化之间以及水量约束与产业结构合理化、高级化、软化之间均存在交互作用。展开更多
基金National Natural Science Foundation of China(Nos.41674009,41574006,41674012)。
文摘In surveying adjustment models,there is usually some uncertain additional information or prior information on parameters,which can constrain the parameters,and guarantee the uniqueness and stability of parameter solution.In this paper,we firstly use ellipsoidal sets to describe uncertainty,and establish a new adjustment model with ellipsoidal uncertainty.Furthermore,we give a new adjustment criterion based on minimization trace of an outer ellipsoid with two ellipsoid intersections,and analyze the propagation law of uncertainty.Correspondingly,we give a new algorithm for the adjustment model with ellipsoid uncertainty.Finally,we give three examples to test and verify the effectiveness of our algorithm,and illustrate the relation between our result and the weighted mixed estimation.
基金supported by the National Natural Science Foundation of China (10872036)the High Technological Research and Development Program of China (2008AA04Z118)the Airspace Natural Science Foundation (2007ZA23007)
文摘In density-based topological design, one expects that the final result consists of elements either black （solid material） or white （void）, without any grey areas. Moreover, one also expects that the optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization method for multidisplacement constraints is proposed in this paper. In the proposed method, the whole optimization process is divided into two optimization adjustment phases and a phase transferring step. Firstly, an optimization model is built to deal with the varied displacement limits, design space adjustments, and reasonable relations between the element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve the optimization problem formulated in the first optimization adjustment phase, by starting with a small design space and advancing to a larger deign space. The design space adjustments are automatic when the design domain needs expansions, in which the convergence of the proposed method will not be affected. The final topology obtained by the proposed procedure in the first optimization phase, can approach to the vicinity of the optimum topology. Then, a heuristic algorithm is given to improve the efficiency and make the designed structural topology black/white in both the phase transferring step and the second optimization adjustment phase. And the optimum topology can finally be obtained by the second phase optimization adjustments. Two examples are presented to show that the topologies obtained by the proposed method are of very good 0/1 design distribution property, and the computational efficiency is enhanced by reducing the element number of the design structural finite model during two optimization adjustment phases. And the examples also show that this method is robust and practicable.
文摘长江经济带是我国重要的水资源聚集区、水生态功能区,但是水环境污染和水资源消耗已成为其可持续发展的障碍。为推动长江经济带绿色高质量发展,本文旨在探究以水资源要素为中心考量长江经济带的资源分配如何影响绿色发展效率,同时厘清长江经济带产业结构调整在其水资源要素影响绿色发展效率过程中发挥的重要作用。论文基于2003—2020年面板数据,运用超效率SBM(slack based measure)模型测算绿色发展效率,分析水资源总量、用水效率和水资源质量三重约束对长江经济带绿色发展效率的影响,并检验了产业结构调整的3个维度,即产业结构合理化、产业结构高级化以及产业结构软化的中介效应及其与水资源约束的交互效应。结果表明:1)水资源约束中用水效率对长江经济带绿色发展效率影响最大,表现为正向促进作用,促进力度表现出上游>中游>下游的特征;2)从中介效应来看,长江经济带全流域主要是产业结构软化在用水效率影响绿色经济发展时发挥了中介作用,分流域来看主要是产业结构高级化发挥了主要作用,产业结构高级化在上游地区水资源总量影响绿色发展效率时表现出了中介作用,在下游地区用水效率、水资源质量影响绿色发展效率过程中也表现出了中介效应;3)从交互效应来看,长江经济带全流域用水效率与产业结构高级化、产业结构软化之间均存在交互作用,此外还存在水量约束与产业结构合理化的交互效应,分区域来看,下游是交互效应作用范围最广的地区,用水效率与产业结构合理化、软化之间以及水量约束与产业结构合理化、高级化、软化之间均存在交互作用。
