关键词： 数学专业   专业排名   录取分数线   逐步回归   多元线性回归  

摘要： 通过分析中国高校数学专业本科发展现状,选取师资力量、人才培养、学术成果、科研投入四个方面的相关因素对36所“985大学”的数学专业得分建立多元线性回归模型。并将用该模型计算得到的数学专业得分表与教育部学位与研究生教育发展中心组织开展的第四轮学科评估结果进行比较,发现模型建立合理且具有一定的实际价值,对回归结果进行分析,探究影响高校数学专业得分的因素,最后对高校数学专业的建设提出合理化建议。

关键词： 知识产权保护强度   区域创新能力   空间溢出效应   空间计量经济模型  

摘要： 利用2008—2017年省级面板数据,运用空间计量模型实证分析知识产权保护强度及其空间溢出效应对区域内外创新能力的影响。结果表明:我国地区创新活动存在明显的空间相关性且沿海发达地区表现为高水平区域创新能力集聚;知识产权保护强度及其溢出效应与地区内外创新能力间呈显著的正向关系;此外,人力资本水平、市场化水平和研发人员投入均可提升区域创新能力。为此政府需正视区域间创新能力的溢出效应,加强知识产权保护强度,加大教育支出投入,提升市场化水平,鼓励并支持更多企业增加研发投入规模,以此激发企业创新积极性。

关键词： economic model predictive control   water distribution networks   operation optimization   risk management  

摘要： For water distribution networks (WDNs) with risks of insufficient water supply, some users' water demand is affected. Because the operation cost is positively related to the number of users whose water demand cannot be met, making the most of the limited water sources to meet the water demand of as many users as possible is the key to reduce the related cost in the operation optimization. Considering the time-varying of users' water demand and the dynamic characteristics of WDNs, real-time dynamic operation optimization of WDNs is required. In this paper, an economic cost function which connects the cost incurred by the risks and the controllable pressure is proposed based on the distribution of users and the corresponding water supply method. An EMPC strategy with the ability to guarantee the closed-loop stability is adopted for the optimization problem. Performance of the proposed methods is illustrated based on the simulation of the Newtown case at different risk levels. Simulation results show that the extra cost decreases greatly in the situation with risks by applying the proposed pressure-related economic function and the EMPC strategy.

关键词： Biomethane   Circular economy   Green transition   Economic analysis   Environmental analysis   Subsidies  

摘要： This paper defines the roles of biomethane for a double-green transition, through the integration of an effective management of renewable energy and municipal waste. The authors perform an assessment of the potential transition of the municipality of Rome to a more sustainable transport system, based on the economic feasibility of production of biomethane as analysed with the Discounted Cash Flow method-ology. The potential reduction of emissions is quantified considering biomethane, to be used as vehicle fuel instead of natural gas. The provision of subsidies is found to be an essential condition to support the development of the biomethane sector. The subsidies must be coordinated with other policies such as the construction and operation of new fuelling stations and the increase of vehicles fuelled by biomethane. Several economic indicators are used to support investors by defining the conditions in which the profitability and economic opportunities are quantified. The transformation of bio-wastes into clean energy, closes the loop and helps societies to make progress toward becoming circular economies, which can contribute to decarbonizing the transport sector. Results of these analyses are applicable in other municipalities, which are currently under-utilizing their organic wastes and by-products. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： EMPC   gold cyanidation leaching process   multi-stage NMPC   scenario tree   uncertainty  

摘要： In order to dynamically operate the gold cyanidation leaching process (GCLP) under uncertainty, a multi-stage economic model predictive control (EMPC) is proposed for GCLP for the transient and steady-state economic optimization. The proposed multi-stage EMPC is composed of two steps. In the first step, the unmeasurable uncertain parameters are estimated by using Tikhonov regularization based method, so as to avoid amplification and propagation of the noise measurements into the estimation. Based on the estimated results, the scenario tree for multi-stage EMPC is generated from the historical data using a data-driven approach, and the control inputs are obtained from solving the resulting large nonlinear programming problem (NLP) at each sampling point. The resulting uncertainty model and the probability of each scenario are more consistent with the actual industrial GCLP, and the solutions are less conservative. The efficiency of the proposed multi-stage EMPC is verified through a simulated industrial GCLP. Compared with other EMPC methods, including classic EMPC and multi-stage EMPC with box uncertainty region, the proposed method can reduce the economic cost while accounting for the constraints at the same time.

关键词： Economics   Cost function   Force   Stability analysis   Linear programming   Mathematical model   Wave energy converter (WEC)   economic model predictive control   economic optimization   convergence  

摘要： In this paper, we propose an economic model predictive control (EMPC) strategy for the constrained optimization problem of the wave energy converter system. Unlike standard model predictive control (MPC) that uses the tracking cost function, in EMPC, a general economic cost function that directly reflects the economic objective of the system is established. In the wave energy converter (WEC), the general economic cost function aims to maximize the energy extracted from ocean waves and minimize the operation cost. The terminal equality constraint in the optimization problem is used to steer the system state to the steady-state at the end of the optimization horizon. Then the controller solves the non-convex optimization problem in real-time. The auxiliary optimization problem is used for the stability analysis, and the convergence of the system can be proved via the Lyapunov technique. Several simulation results are presented to demonstrate the effectiveness of the proposed strategy.

关键词： 空间计量经济模型   GIS技术   贫困格局   贫困影响因素   寻甸回族彝族自治县  

摘要： [目的]贫困问题是当今社会的热点之一。科学揭示县级区域贫困格局、分析致贫因子,可以促进县级区域性减贫战略更好地实施。[方法]文章运用多种空间计量经济模型和地理信息系统(GIS)技术,研究了国家级贫困县——云南省寻甸回族彝族自治县的贫困格局,多维度剖析该区域致贫因素。[结果](1)寻甸县农村贫困具有明显的区域性差异和贫困空间效应,其贫困发生率的分布具有一定的空间特征,并在一定程度上受到地形条件的影响,呈现一定的地域差异性。总体上,寻甸县南部、县政府所在的街道仁德及其附近地区的贫困发生率普遍较低,该县北部的联合乡、六哨乡、甸沙乡等乡镇贫困发生率居于较高水平,其主要原因是这些乡镇的区位条件和地形条件相对较差。(2)相比2014—2016年,2017年寻甸县各乡镇(街道)的贫困发生率显著降低,其原因主要是2017年该县对所有排查出的"问题户"进行整体性的高强度整改、使得2017年末该县多数贫困户得以脱贫。(3)空间误差模型(随机效应)估计结果表明,农民人均纯收入的提高、农村居民恩格尔系数的降低、农村居民人均用电量的增加、每公顷耕地农业机械总动力的增加、少数民族人口比例的降低均可促进贫困发生率下降。[结论]多数因素对贫困发生率的影响强度各不相同,具有明显的空间差异性。新时期中国西南山区贫困格局、致贫因素、减贫路径及模式,亟需深入研究,这也对强化贫困地理学的研究带来了新机遇和新挑战。

关键词： GDP数据质量   计量经济模型   统计数据诊断   随机数值模拟　　quality of GDP statistics   econometric models   diagnosis of statistical data   stochastic numerical simulation  

摘要： 针对中国GDP数据质量评估研究中广泛采用的计量经济模型方法，本文从其技术原理的局限性以及GDP核算误差发生机制的影响效应两个方面，系统考察了该方法在具体评估实践中的适用性。研究表明，基于计量经济模型的两类评估方法（参数可靠性分析与异常数值识别），在实际操作中易于陷入“数据质量不佳”或者“模型结构设定不当”的对立解读困境；因忽视了GDP核算误差的发生机制，根据模型估计结果的异常特征来反推GDP数据序列中误差结构（效应），其可行性有所不足。计量模型方法之于GDP数据质量评估研究的适用性的提升，还有待于对GDP核算误差机制的显性识别；本文在此方面提供了一个相对完备的概念性基准模型，有助于相关研究的进一步深化拓展。

关键词： 数学素养   经济模型   时间价值  

摘要： 众所周知,对数字敏感是作为一名财会人员的最基本素养,许多优秀的经济学家在数学领域也颇有建树。本文总结了数学与经济学的联系以及数学在经济学中运用的局限性,包含数学在经济学研究领域占有的地位、二者之间的异同。

关键词： 就业   人口结构   空间相关性   空间计量经济模型  

摘要： 党的“十九大”明确指出,要改善民生,提供相应的保障,提高就业质量,提高人民收入水平。由此看出,就业是最大的民生,实现就业稳定一直以来都是政府制定宏观政策的重要目标之一。然而,新时期广西人口结构的变化对就业政策提出了更多现实要求。因此,本文以广西地级市为着眼点,对广西人口结构与就业关系进行研究。本文选用广西14个地级市10年(2009-2018)的面板数据作为研究对象。首先,对人口结构理论以及空间计量经济学方法进行了简要的回顾。其次,对广西人口结构进行时空演变分析。然后,选用地理距离空间权重矩阵,采用莫兰指数检验就业方面的全局空间相关性和局部空间相关性,在此基础上运用空间计量模型对就业及其人口结构影响因素进行了检验分析,通过比较所建立的模型,得出随机效应空间杜宾模型能较好的反映出广西人口结构与就业关系的空间效应。结果显示:第一,广西人口总量平稳增长,人口性别比均超出正常范围值,各阶段人口比重波动均不太明显,学前教育和高等教育呈明显上升趋势,广西市镇人口比重呈不断上升趋势,城镇化进程不断发展。第二,广西区域就业存在显著的空间正相关性,进一步分析了四个时间点(2009年、2012年、2015年及2018年)的区域就业局部莫兰散点图,得出广西不同地市的就业也存在局部的H-H、L-H、L-L和H-L等集聚形式的空间相关性,在整体上具有相同空间自相关性的地市达到70%以上;第三,广西各地市间的就业状况存在显著的空间溢出效应,人口规模结构对本地就业水平的提高产生显著的负面影响,但却对相邻地市的就业水平产生显著的正面影响;人口性别结构不仅对本地区就业水平产生显著的负面效应,还对相邻地市的就业水平产生显著的负面影响;城镇化率对本地区和邻近地区的就业率提高产生显著的正面效应。在影响广西区域就业的诸因子中,人口总量结构、人口性别结构对区域就业水平具有抑制作用,人口城乡结构对区域就业水平具有促进作用,人口文化结构影响不显著。最后,根据实证分析所得到的对广西人口结构与就业关系的研究结论,从资源配置方面提出对如何促进广西区域就业与人口结构相适应提出了政策建议。