Non-cooperative implementation: A survey of recent results

Strategic decentralization of collective decision-making is considered when the agents' behaviour is non-cooperative. Specifically they use dominant, maximin risk-avert or sophisticated strategies. The existing results applying these equilibrium concepts are reviewed in three familiar economically meaningful contexts: ordinal (as in voting), random (as in bargaining) and quasilinear (as in public goods problems).     

Residual‐based artificial viscosity for simulation of turbulent compressible flow using adaptive finite element methods

In this paper, we present a finite element method with a residual‐based artificial viscosity for simulation of turbulent compressible flow, with adaptive mesh refinement based on a posteriori error estimation with sensitivity information from an associated dual problem. The artificial viscosity acts as a numerical stabilization, as shock capturing, and as turbulence capturing for large eddy simulation of turbulent flow. The adaptive method resolves parts of the flow indicated by the a posteriori error estimates but leaves shocks and turbulence under‐resolved in a large eddy simulation. The method is tested for examples in 2D and 3D and is validated against experimental data. Copyright © 2012 John Wiley & Sons, Ltd.     

An ALE finite element method for a coupled Stefan problem and Navier–Stokes equations with free capillary surface

In this article, an ALE finite element method to simulate the partial melting of a workpiece of metal is presented. The model includes the heat transport in both the solid and liquid part, fluid flow in the liquid phase by the Navier–Stokes equations, tracking of the melt interface solid/liquid by the Stefan condition, treatment of the capillary boundary accounting for surface tension effects and a radiative boundary condition. We show that an accurate treatment of the moving boundaries is crucial to resolve their respective influences on the flow field and thus on the overall energy transport correctly. This is achieved by a mesh‐moving method, which explicitly tracks the phase boundary and makes it possible to use a sharp interface model without singularities in the boundary conditions at the triple junction. A numerical example describing the welding of a thin‐steel wire end by a laser, where all aforementioned effects have to be taken into account, proves the effectiveness of the approach.Copyright © 2012 John Wiley & Sons, Ltd.     

Consistent Finite Element Calculations of Boundary and Internal Fluxes

The purpose of this paper is to develop a consistent method to calculate the fluxes or the stresses in an incompressible flow, particularly a turbulent flow. A post-processing technique has been developed such that fluxes or stresses are treated as unknown values, which are solved for, weakly, using the finite element method.

The method has been applied to calculate the Reynolds stresses in a turbulent channel flow. As a result of the new consistent method, the Reynolds stresses have shown good agreement with the DNS data confirming the momentum conservation of the finite element method.     

Obtaining the dividends-penalty identities by interpretation

The dividends-penalty identity is a relation between three functions: the discounted penalty function without dividends, the discounted penalty function if a barrier dividend strategy is applied, and the expected discounted dividends until ruin. The classical model of risk theory is modified in that the deterministic premiums are replaced by a compound Poisson process with exponential jumps. In this model, the dividends-penalty identity is new and can be derived by interpretation. Then the dividends-penalty identity in the classical model is obtained as a limit.     

Generalization of the main equation of differential game theory

We consider feedback, two-person, zero-sum differential games. We obtain two inequalities for the directional derivatives of the nonsmooth value function. We show that these inequalities, together with the boundary conditions, constitute necessary and sufficient conditions which the value function must satisfy. In the region where the value function is differentiable, the inequalities become the well-known main equation of differential game theory (Isaacs-Bellman equation). The results obtained here may be useful in the approximation of the value function by piecewise smooth splines and also in the classification of singular surfaces.The author would like to thank Academician N. N. Krasovskii for his valuable advice and encouragement.     

竞争情形下服务商质量保证策略研究

质量保证策略是服务商获取竞争力的重要手段之一。本文在考虑服务商及其竞争对手的质量承诺水平和质量承诺补偿对其服务需求影响的基础上,构建了质量承诺水平、质量承诺补偿、质量承诺水平和质量承诺补偿三种竞争情形下的博弈模型,并系统分析了不同模型下的质量保证策略。研究发现:一旦有服务商提高质量承诺水平或质量承诺补偿,在质量承诺水平竞争模型下,其他服务商可适当地降低质量承诺水平,而在质量承诺补偿竞争模型下,其他服务商会同时提高质量承诺补偿。此外,在质量承诺水平和质量承诺补偿竞争模型下,若质量承诺水平的成本系数满足一定条件,各个服务商之间会存在纳什均衡。本文对服务市场竞争情形下服务商质量保证策略的制定具有一定的实践意义。     

SISO多维控制系统的反馈镇定性及算法的数学机械化实现

从代数学的理想论以及代数簇理论,探讨了SISO多维控制系统的可反馈镇定条件,并给出反馈控制的表示.文中的主要结果建立在判定一个多变元多项式的零点集是否与由多项式刻画的凸集相交的前提之上,并用数学机械化方法实现了这一判定的过程.     

Improving biorefinery planning: Integration of spatial data using exact optimization nested in an evolutionary strategy

Biorefineries can provide a product portfolio from renewable biomass similar to that of crude oil refineries. To operate biorefineries of any kind, however, the availability of biomass inputs is crucial and must be considered during planning. Here, we develop a planning approach that uses Geographic Information Systems (GIS) to account for spatially scattered biomass when optimizing a biorefinery’s location, capacity, and configuration. To deal with the challenges of a non-smooth objective function arising from the geographic data, higher dimensionality, and strict constraints, the planning problem is repeatedly decomposed by nesting an exact nonlinear program (NLP) inside an evolutionary strategy (ES) heuristic, which handles the spatial data from the GIS. We demonstrate the functionality of the algorithm and show how including spatial data improves the planning process by optimizing a synthesis gas biorefinery using this new planning approach.     

东南部欠发达地区县域城乡空间统筹发展的规划思考

山区县由于其特殊的空间条件和战略地位决定了其发展战略和规划建设的特殊性和复杂性.以位于浙江南部丽水境内的景宁畲族自治县为例,研究山区县域发展所面临的关键问题及经济、社会、城镇发展模式的抉择,从而理清发展战略规划的研究思路并提出空间规划对策,以期对山区县经济社会综合发展以及空间发展策略提供案例借鉴.