关键词： 集约利用   国土空间   测度   影响机理   影响因素   空间计量经济模型   GIS   县域   中国  

摘要： 土地利用问题日益成为中国经济发展的重要约束力之一。快速城镇化背景下城镇和乡村的快速扩张吞噬了宝贵的土地资源,粗放非集约的利用方式更加剧了土地资源的浪费。从国土空间集约利用的影响机理出发分析中国县域国土空间集约的影响机理对指导集约利用实践以及宏观集约利用政策瞄准和政策矫正都具有特殊意义。综合运用OLS模型、空间面板滞后模型和空间面板自相关模型以GIS和Matlab为技术平台,构建中国县域发展基础数据库(1992-2010年),定量刻画中国2286个县级单元的空间集约利用度时空变化格局,计量分析社会经济发展、自然环境本底、区位交通地理、宏观战略政策和历史基础5大类变量17项具体因素的影响机理。研究结果表明,空间面板数据模型的整体显著性和可信度检验略高于一般面板数据OLS模型;在固定相关效应后对各因素的影响机制进行了检验,表明工业化、城镇化、经济发展水平、区位、交通和宏观战略政策等因素对县域国土空间集约利用的影响较为明显。自然环境因素弱于社会经济因素。被忽略的历史因素对县域国土空间集约利用具有极显著的影响。未来县域国土空间集约利用应因势利导,强化有利因素,减小不利因素影响。提高工业化和城镇化发展水平和质量。发挥市场的主导作用,完善土地市场和运行机制。优化国土空间集约利用调控政策和管治手段,制定差别化的空间集约利用政策。以资源环境承载力为基础和约束最大限度地提高投入和产出水平。

关键词： 光伏电站   经济模型   投资评价  

摘要： 在国家政策的支持下,光伏电站投资达到了新的高峰。在光伏发电系统中,光伏组件阵列的支架运行方式直接决定了光伏发电系统的发电能力。以内蒙古赤峰地区气象资料为依据,通过设定经济模型计算发电收益、电价竞争力对比,对目前光伏发电系统中常用的固定式支架、斜单轴式跟踪支架、双轴式跟踪支架提出设计选型分析,为光伏电站支架选型提出建议。

关键词： 经济模型   品茶   男人   思维模式   函数数据   质量模型   定量标准   茶园  

摘要： 云南，茶园。在山谷中氤氲的雾气里，绿色的茶树时隐时现，直若人间仙境。行在茶园，辅以茶中那韵味隽永的文化，最易触动人的感悟。可是对初来这座茶园的宋铭阳来说，眼前如画的美景只是让他感叹了片刻，很快，专业所养成的思维模式便自动开启了70在他眼中，这茶园中不同位置、种类的茶树，不同成熟度、大小的叶芽，都自动变成了一组组函数数据，开始填入成一个复杂的茶叶工艺质量模型，并不断修正推演。这个模型最终输出的结果是能够改变眼前茶园收入的定量标准。

关键词： 高速公路   公路经济   项目选择   双层规划   出行成本   预算约束  

摘要： 分别以车辆出行成本节约与通行收入增加的总和最大及车辆出行广义费用最小作为上、下层模型的目标函数,构建高速公路路面养护项目选择的双层规划模型,在交通量动态分配的基础上采用搜索算法对模型进行求解,同时考虑养护路段施工难度、交通瓶颈、路段安全水平及路段重要度等因素综合判定最优养护方案。结果表明:定量计算与定性指标分析相结合能得出高速公路路面养护项目的最优选择方案,计算结果可反映路段养护的经济效益。

关键词： Efficiency wage   cost-benefit   turnover   pharmacist  

摘要： Professional articles regarding managerial means to address pharmacist turnover generally focus on policy and psychological dimensions in lieu of relative cost analysis. We present a cost-benefit argument, based on 'efficiency wage theory' from the economics literature to reduce the rate of pharmacist turnover in retail establishments and hospitals. Drawing from national pharmacist data, we discuss the rationale for how much management could enhance pharmacist salaries in an organization to cost effectively reduce the turnover rate. We suggest using the approach as an adjunct to existing managerial policies aimed at reducing pharmacist turnover.

关键词： Computational economics   Exploration of agent-based models   Design of experiments   Meta-modeling  

摘要： Extensive exploration of simulation models comes at a high computational cost, all the more when the model involves a lot of parameters. Economists usually rely on random explorations, such as Monte Carlo simulations, and basic econometric modeling to approximate the properties of computational models. This paper aims to provide guidelines for the use of a much more efficient method that combines a parsimonious sampling of the parameter space using a specific design of experiments (DoE), with a well-suited metamodeling method first developed in geostatistics: kriging. We illustrate these guidelines by following them in the analysis of two simple and well known economic models: Nelson and Winter's industrial dynamics model, and Cournot oligopoly with learning firms. In each case, we show that our DoE experiments can catch the main effects of the parameters on the models' dynamics with a much lower number of simulations than the Monte-Carlo sampling (e.g. 85 simulations instead of 2,000 in the first case). In the analysis of the second model, we also introduce supplementary numerical tools that may be combined with this method, for characterizing configurations complying with a specific criterion (social optimal, replication of stylized facts, etc.). Our appendix gives an example of the R-project code that can be used to apply this method on other models, in order to encourage other researchers to quickly test this approach on their models.

关键词： Economic model predictive control   Average constraints   Nonlinear systems  

摘要： In this paper, we thoroughly investigate various aspects of economic model predictive control with average constraints, i.e., constraints on average values of state and input variables. In particular, we first show that a certain time-varying output constraint has to be included into the MPC problem formulation in order to ensure fulfillment of these average constraints. Optimizing a general (possibly economic) performance criterion may result in a non-converging behavior of the corresponding closed-loop system. While such a behavior might be acceptable in some cases, it may be undesirable for other types of applications. Hence as a second contribution, we provide a Lyapunov-like analysis to conclude that indeed asymptotic convergence to the optimal steady-state follows if the system satisfies a certain dissipativity condition. Finally, for the case that this dissipativity property is not satisfied but still a convergent behavior of the closed-loop is required, we examine two different methods how convergence can be enforced within an economic MPC setup by imposing additional average constraints on the system. In the first method, an additional average constraint is defined which results in the system being dissipative, while the second consists of imposing an additional even zero-moment average constraint. We illustrate our results with various examples. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： forest engineering   operations research   timber harvest   transportation   bilevel planning  

摘要： This paper presents an economic model for the optimization of a vertically integrated timber harvesting operation. The operations of road construction, timber yarding, and log truck hauling are collectively optimized. The harvest unit has two centralized landings that are to be accessed by truck road from a single existing road takeoff point. The harvest unit is located on level, unvarying terrain with uniformly distributed log turns. Formulas for the optimal yarding boundary between the landings, areas yarded to each landing, and the average yarding distances are derived. These formulas are then used in the bilevel optimization of a vertically integrated timber harvesting operation. Numerical examples are presented and discussed.

关键词： ECONOMIC models   PREDICTION theory   HYDROCARBONS   REGENERATORS   FEEDSTOCK   NONLINEAR analysis  

摘要： Fluid catalytic cracking (FCC) is an important refinery process by which heavy hydrocarbons are cracked to form lighter valuable products over catalyst particles. FCC plants consist of the riser (reactor), the regenerator, and the fractionator that separates the riser effluent into the useful end products. In FCC plants the product specifications and feedstocks change due to varying economic and market conditions. In addition, FCC plants operate with large throughputs and a small improvement realized by optimization and control yields significant economic return. In previous work, we developed a nonlinear dynamic model and validated it with industrial data. In this study, our focus involves the development and application of a real-time optimization framework. We propose a hierarchical structure which includes a two-layer implementation of economic model predictive control (EMPC). EMPC provides the optimal riser and the regenerator temperature reference trajectories which are determined from a dynamic optimization problem maximizing the plant profit. A regulatory model predictive controller (RMPC) manipulates the catalyst circulation rate and the air flow rate to track the reference trajectories provided by EMPC. We consider changes in product prices and the feed content, both of which necessitate online optimization. Dynamic simulations show that the proposed hierarchical control structure achieves optimal tracking of plant profit during transitions between different operating regimes thanks to the combined efforts of EMPC and RMPC.

关键词： 货币   宏观经济模型   作用  

摘要： 本文重点讨论货币在现代宏观经济模型中的作用,目的在于理解货币在构建模型时所得出的结论,以及现代宏观经济模型引入货币时应该考虑的问题,从而为更加准确的构建宏观模型,合理运用模型研究宏观经济问题提供参考。本文首先介绍了货币作用的研究背景,提出了现代宏观经济模型中存在的问题,并探讨了存在这些问题的原因。