关键词： 商品进口额   计量经济模型   影响因素  

摘要： 自从我国2001年加入WTO至今,对外贸易发展速度急速提高,对外贸易依存度也相应得到提升,这也提升了我国在国际市场中的地位。国际市场需求虽然为我国经济增长提供了极大的推动力,若处理不到位便会造成阻碍。为了避免这种阻碍的发生,必须了解进出口贸易总额影响因素。文章围绕商品进口额中计量经济模型的影响因素,通过建模分析的方式展开研究,最终明确了几项直接因素,并提出了建议,旨在减少对外贸易摩擦,推动贸易发展。

关键词： 日本鲐   Pella-Tomlinson模型   环境因子  

摘要： 【目的】建立基于环境因子的生物经济模型,研究环境因子对鲐鱼资源的影响。【方法】根据2006—2015年中国鲐鱼生产统计鱼产卵场和索饵场海洋表面温度(SST)、索饵场海洋表面温度梯度(GSST)和索饵场海表面高度(SSH)等数据,假设产卵场和索饵场环境因子对东、黄海日本鲐剩余产量产生影响,基于剩余产量模型分析环境因子对东、黄海日本鲐资源的影响。【结果与结论】产卵场和索饵场关键因子共同影响内禀增长率r,产卵场关键因子影响环境容纳量K,进而影响剩余产量和资源量;2011、2012和2015年日本鲐遭受过度捕捞;每年的最大可持续产量(MSY)、最大经济产量(MEY)和生物经济参考点(BE)及其对应的捕捞努力量fMSY、fMEY和fBE随着环境因素的改变而变化。在渔业管理中应考虑环境因素。

关键词： 创新效率   经济增长   空间计量经济模型  

摘要： 本文对区域创新效率(包括研发效率和商业化效率)进行了测度,并建立空间计量模型,对创新效率对经济增长的影响进行了检验,研究结果表明:(1)无论是从研发效率,还是从商业化效率来看,东部地区都处于相对领先地位,中部地区紧随其后,西部地区的创新效率最低。我国区域商业化效率明显低于研发效率,绝大多数区域在促进科技成果转移转化方面还表现欠佳。(2)创新效率对区域经济增长有正面的影响,但不及资本和劳动力的影响大,创新尚未成为推动我国区域经济增长的主要动力。(3)尽管我国经济增长在省际间存在溢出效应,但与创新效率、资本、人力投入对经济增长的影响相比,这种溢出效应还不大,区域增长极的辐射带动潜力还有待增强。

摘要： Nonalcoholic steatohepatitis (NASH) is the progressive form of nonalcoholic fatty liver disease. Our aim was to estimate the total economic burden of NASH and advanced NASH in the United States. We constructed lifetime Markov models for all stages of NASH and a separate model to specifically identify the increased burden of advanced NASH (fibrosis stage >3). The models comprised patients aged 18+, who moved through seven different health states. We used a lifetime horizon with 1-year cycles for each transition. Cohort size was estimated using US population data, and prevalence and incidence rates were obtained from the literature. Transition probabilities between states were derived from meta-analyses. Costs included inpatient, outpatient, professional services, emergency department, and drug costs, which were obtained from the Center for Medicare and Medicaid Services Fee Schedule 2017 and published data. All future costs were discounted at an annual rate of 3%. Our models estimated that there are 6.65 million adults (18+ years old) with NASH in the United States and that there were 232,000 incident cases in 2017. Lifetime costs of all NASH patients in the United States in 2017 will be $222.6 billion, and the cost of the advanced NASH population will be $95.4 billion. Conclusion: NASH, especially advanced NASH, is associated with high lifetime economic burden;in the absence of treatment, the total direct costs of illness for these patients will continue to grow, and these costs would be even greater if the societal costs are included.

关键词： 产业转移   产业转移承接   空间计量经济模型   豫皖湘赣  

摘要： 豫皖湘赣四省是新一轮产业转移的重要承接地。利用标准差、变异系数、赫芬达尔指数、聚类分析、ESDA及空间计量经济模型等方法对四省承接产业转移的区域差异及影响因素进行研究。研究表明:(1)豫皖湘赣四省承接产业转移的总量和绝对差异都在拉大,相对差异和集中程度都在降低后,有趋于稳定趋势;(2)空间分布上大致形成以省会城市为核心、中间高四周低的圈层等级结构;(3)空间格局上,空间集聚态势进一步强化,逐步形成以郑州市和南昌市为核心的两大高高集聚区;(4)空间交互作用是四省承接产业转移空间差异形成的重要因素;(5)劳动力成本对产业转移有负向作用,经济发展水平、市场吸引力、技术创新能力、集聚效应、成本因素、对外开放度、区位条件及产业结构对产业转移具有正向作用,市场吸引力、集聚效应及对外开放度影响最大。

关键词： 河北省粮食产量   化肥施用量   粮食作物播种面积   回归分析影响因素  

摘要： 农业是国民经济的基础产业,粮食是人类赖以生存和发展的必需品,保证粮食安全是一个永恒课题。选取河北省2001～2016年16年的数据,运用线性回归方法建立了影响粮食产量的计量经济模型,并借助E-views8.0软件对模型进行OLS等分析检验。结果表明,影响河北省粮食产量因素的二大因素是化肥施用量和粮食作物播种面积,其中影响最大的是化肥施用量。最后,提出增加粮食产量必须合理施用化肥,保持粮食作物播种面积,增加资本和技术投入,加大对各种自然灾害防御的对策建议。

关键词： Computational techniques   uncertainty quantification   sensitivity analysis   polynomial chaos expansion  

摘要： We present a global sensitivity analysis that quantifies the impact of parameter uncertainty on model outcomes. Specifically, we propose variance-decomposition-based Sobol' indices to establish an importance ranking of parameters and univariate effects to determine the direction of their impact. We employ the state-of-the-art approach of constructing a polynomial chaos expansion of the model, from which Sobol' indices and univariate effects are then obtained analytically, using only a limited number of model evaluations. We apply this analysis to several quantities of interest of a standard real-business-cycle model and compare it to traditional local sensitivity analysis approaches. The results show that local sensitivity analysis can be very misleading, whereas the proposed method accurately and efficiently ranks all parameters according to importance, identifying interactions and nonlinearities.

关键词： Distributed economic MPC   Residential microgrids   Distributed battery energy storage systems   Dissipativity  

摘要： In this work, a dissipativity based distributed economic model predictive control (DEMPC) approach is developed for the operation of battery energy storage (BES) networks in residential microgrids. With the presence of a microgrid power market (MPM), control of the BES systems is formulated as a self-interested distributed control problem, as individual DEMPC controllers minimize their local economic cost functions based on the price prediction of MPM. Due to the intermittent nature of photovoltaic (PV) power generations and load demands, the DEMPC without proper coordination or constraints may lead to excessive energy trading and price oscillations in MPM. To solve this problem, dissipativity theory with dynamic supply rates is adopted in this paper to deal with the interactions between individual users and the MPM. The microgrid-wide performance requirement of attenuation of the net power fluctuations with respect to time-varying PV generation and demands, is converted into the dissipative trajectory constraints imposed on individual DEMPC controllers. The proposed approach is scalable as it does not require online iterative optimizations across the controller network. A case study is presented to illustrate the proposed method. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Constrained control   nonlinear model predictive control (MPC)   reference tracking   incremental stability  

摘要： In this paper, we study the system theoretic properties of a reference tracking model predictive control (MPC) scheme for general reference trajectories and nonlinear discrete-time systems subject to input and state constraints. Contrary to other existing theoretical results for reference tracking MPC, we do not modify the optimization problem with artificial references or terminal ingredients. Instead, we consider a simple, intuitive implementation and derive theoretical guarantees under a stabilizability condition on the system and suitable conditions on the reference trajectory. We provide sufficient conditions for exponential reference tracking for reachable reference trajectories. In addition, we study unreachable reference trajectories and derive sufficient conditions to ensure practical stability of the unknown optimal reachable reference trajectory. For both cases, we characterize the region of attraction. The results build on the notion of incremental stabilizability, strict dissipativity, and results in (economic) MPC without terminal constraints.

关键词： Optimal control   Subsystem decomposition   Wastewater treatment   Nonlinear systems  

摘要： In this work, we consider the distributed economic model predictive control (EMPC) of a wastewater treatment plant described by Benchmark Simulation Model No. 1 and compare its performance with two commonly used control methods. The plant is decomposed into two subsystems based on the topology of the process, the requirement in our distributed control system design and the computational considerations. A local EMPC controller is designed for each subsystem. Two different designs are considered. In the first design, the centralized model is used in each subsystem EMPC controller design;and in the second design, a subsystem model is used in each subsystem EMPC design. The performance of these two distributed EMPC designs are compared with a centralized model predictive control (MPC) scheme and a centralized EMPC scheme from different aspects including effluent quality, operating cost, and computational efficiency. The simulation results demonstrate that the distributed EMPC with each subsystem EMPC controller designed based on the entire system model is more favourable in terms of control performance. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.