关键词： Power generation   Predictive models   Economics   Stability analysis   Thermal stability   Informatics   Optimization   Deep belief network (DBN)   economic model predictive control (EMPC)   time delay   ultrasupercritical (USC) power plant  

摘要： The dynamic economic optimization of the ultrasupercritical (USC) boiler-turbine unit has become an important task in modern power plants. Economic model predictive control (EMPC) has recently developed to be a promising method for realizing the dynamic economy. This EMPC essentially requires a highly reliable model for USC dynamic prediction which could reflect the internal mechanism of USC with big data feature. This article constitutes a deep-neural-network-based EMPC for the USC unit. Deep belief network (DBN) is used to model the USC unit with mathematical structure. To overcome the nonlinearity and time delay existing in the pulverized channel, an augmented model with predictor embedded is also incorporated into the EMPC design. The auxiliary controller and stability region have been constituted to guarantee closed-loop stability. Simulation results on a 1000-MW USC unit fully demonstrate the effectiveness of the proposed DBN-based EMPC.

关键词： Protein crops   Manure   Nitrogen efficiency   Complementarity   Mathematical programming  

摘要： Agricultural specialization has disconnected crop and livestock production in many farms and regions. As a result, crop farms are deficient in nitrogen to fertilize their crops, while livestock farms are deficient in proteins to feed their animals. The increased consumption of nitrogen rich input raised economics and environmental questions. In this study, we tested two mechanisms to reconnect crop and livestock production: increasing legume production and developing farm-to-farm exchanges of crops and manure. To do so, we developed the SYNERGY bio-economic model, which represents specialized farm types in a region and models exchanges between them. Applied to western France, it analyzes economic, technical and environmental impacts. When the legume share reached 10% of the region's area, legume production increased more on crop farms than on livestock farms and its use in feed was still limited. When farms could export more manure, legume production increased but N losses increased due to an intensification of pig production. This rebound effect offset the environmental benefits linked to the decrease in synthetic N fertilizers use. When local crop exchanges were possible, they remained limited and did not affect indicators. Thus, the two levers studied are insufficient to improve sustainability, mainly because of high livestock production.

关键词： 脱硫系统   数学建模   多目标优化   经济模型   预测控制  

摘要： 提出了一种基于脱硫系统工艺特性的多目标经济模型预测控制方案,以预测控制为基础,将脱硫剂成本指标、排放性能指标、系统运行电耗指标等经济和控制目标作为决策因素,探索了该优化策略在工况变动时的控制表现,重点考察了脱硫系统在炉负荷变动、排放指标变动、pH波动下的实时优化效果。结果表明:该策略能较好满足系统经济性、安全性、控制平滑性、排放要求等多种控制目标,控制稳定性强,具有良好的多目标实时优化能力。

关键词： 农产品短缺点   农业   对外直接投资   开放二元经济模型  

摘要： 本文基于开放二元经济模型和小岛清的比较优势理论,对转型国家的农业对外直接投资进程进行了理论分析,并对中国的数据展开了验证,研究结果发现:(1)转型国家在农业生产率增长迟缓、农业劳动力不足以及农业资源禀赋限制的条件下,将会迎来开放条件下的农产品短缺点,进而推动农业对外直接投资的进程,而且农业对外直接投资与农产品进口之间存在互补关系。(2)最晚在2009年中国迎来了开放条件下的农产品短缺点,农业劳动力和农业资源禀赋是影响中国农业对外直接投资的重要因素。(3)中国农业对外直接投资具有效率寻求和农业资源寻求的动机,自2009年以后中国农业对外直接投资在更多地寻求农业资源。(4)中国农业对外直接投资与农产品进口存在显著的互补关系,工业增长扩大了中国的农产品进口。本文的研究为转型国家的农业对外直接投资进程提供了理论支持并揭示了其发展规律。

关键词： 教育   科技进步   经济增长   动力系统  

摘要： 为了研究科技进步与经济发展的关系,构建了一个改进的含有教育和科技进步的经济模型.基于一定的假设,建立了一个非自治微分动力系统,并通过变换将其转为自治微分动力系统;利用稳定性理论得出自治系统稳定的一个充分条件,数值模拟实验验证了系统的稳定性;给出了经济、教育等变量的增长率,表明科技进步和教育对经济增长都具有重要的意义.

关键词： 疫情危机   金融危机   总供给——总需求   宏观经济模型   边际分析   溢出效应  

摘要： 本文基于经济学视角下,首先通过对比分析对疫情危机和金融危机的界定进行了定性研究;通过供求分析和经济周期规律分析和预测了疫情的影响;根据AD-AS模型判断疫情危机的性质后,基于供求分析、成本-效益原则、IS-LM模型和溢出效益讨论了政策工具和风险,基于此对未来政策提出相关可行性建议。疫情危机由外生因素主导,是复杂的全球性危机,远远超过金融危机带来的影响,对经济的影响主要取决于疫情持续时间、过程中生产能力的存续以及经济体本身的结构合理性,各国应以抗疫为中心,活用政策工具救助经济,联合统一度过这次全球危机。

关键词： 次贷危机   房地产市场   宏观经济模型  

摘要： 随着当时次贷危机的全面爆发,我国经济面临严重的下滑压力,作为我国拉动经济增长的主要引擎之一的房地产市场也出现明显的衰退趋势,为此政府出台了稳定房地产市场的相关政策措施。利用宏观经济模型,对房地产市场的政策干预进行实践和理论上的对比分析,对审慎思考中国宏观经济状况有着积极的意义。

关键词： 蛛网模型   稳定性   极限环   周期解   数值模拟  

摘要： 基于单一商品数量与其价格之间的互动关系构建了蛛网经济微分动力学模型,分析了该模型平衡点的稳定性,给出了其极限环存在的充分条件.在脉冲扰动的条件下,构建了脉冲时刻固定和状态自治的两个蛛网经济模型,探索了前者边界周期解的全局渐近稳定性,研究了后者半平凡周期解的稳定性.最后用数值模拟验证了相关结论的正确性.

关键词： 经济计量学   经济模型   计量方法   截面数据   数量经济学   统计学  

摘要： 现代经济计量模型和方法均是源生于经济学家所掌握的数据或所面临的问题。经济学研究中,所有模型的构建、计量方法的应用都依赖于数据。经济计量分析中的数据基本可分为截面数据、时间序列数据、面板数据以及通过统计调查获取的微观数据。由这几类数据,源生、发展了一系列经济模型、参数估计方法、模型检验方法等。应依托经济数据,梳理经典的经济计量模型、方法,重构现代经济计量学的方法论体系。

关键词： Economic model predictive control   Hybrid Gaussian process   Long-term forecasting   Unknown disturbances  

摘要： This paper proposes a hybrid Gaussian process (GP) approach to robust economic model predictive control under unknown future disturbances in order to reduce the conservatism of the controller. The proposed hybrid GP is a combination of two well-known methods, namely, kernel composition and nonlinear auto-regressive. A switching mechanism is employed to select one of these methods for disturbance prediction after analyzing the prediction outcomes. The hybrid GP is intended to detect not only patterns but also unexpected behaviors in the unknown disturbances by using past disturbance measurements. A novel forgetting factor concept is also utilized in the hybrid GP, giving less weight to older measurements, in order to increase prediction accuracy based on recent disturbances values. The detected disturbance information is used to reduce prediction uncertainty in economic model predictive controllers systematically. The simulation results show that the proposed method can improve the overall performance of an economic model predictive controller compared to other GP-based methods in cases when disturbances have discernible patterns. (C) 2020 Elsevier Ltd. All rights reserved.