基于基尼系数的耕地保有量分配优化模型

为了确保粮食安全,我国政府强调18亿亩耕地红线坚决不能突破,但未提出耕地保有量在各个地区如何进行公平分配。针对此问题,借鉴基尼系数,构建我国耕地保有量公平分配的优化模型。以2010年各省（市、自治区）的耕地保有量公平分配为例,利用各地区现有耕地面积数据,选取各地区人口、二三产业产值、粮食产量、农用地面积、水资源总量、≥10℃年积温、太阳辐射作为指标,结合各地区粮食自给率与后备耕地资源,构建基于基尼系数的耕地保有量分配优化模型,利用Lingo软件求出模型最优解并结合GIS技术绘制各地区耕地面积增减比例图。根据优化后耕地面积增减量占现有耕地面积的比例,我国各地区耕地面积需要调整情况可以分为五类：耕地削减区、耕地保持区、耕地小幅度增加区、耕地中幅度增加区、耕地大幅度增加区。结论表明,基于基尼系数的耕地保有量分配结果既公平又可行,可为耕地保护提供借鉴。     

旅游发展背景下乡村景观格局变迁与优化

乡村景观是发展乡村旅游的资源基础,在旅游发展背景下,乡村景观格局的反向变迁威胁着乡村景观的乡村性,不利于乡村旅游的可持续发展。文章提出,调控乡村旅游发展目标、人类行为和乡村景观空间格局三个要素,是控制和治理乡村景观反向变迁,实现乡村景观优化的主要路径,政府的主导、扶持、规范和引导是乡村景观优化的必要条件。     

转型期中国土地利用的时序优化与空间释放

随着中国经济快速发展和人口集聚,建设用地需求快速增加,土地供需矛盾日益突出,资源保护和管理的压力逐渐加大。中国经济已步入新常态,经济结构转型倒逼土地供应结构优化调整。发达国家城镇化发展阶段起步较早,在土地节约集约利用与管理方面积累了宝贵经验。结合中国城市土地利用现状,借鉴美国、英国、德国等发达国家土地利用与管理经验,可从盘活存量土地、提高土地供给精准度、建立多元化供地机制三方面实现土地节约集约利用及有效管理,促进供给侧结构性改革。     

The spatial and temporal variation in passenger service rate and its impact on train dwell time: A time-series clustering approach using dynamic time warping

This study aims to improve the understanding of the underlying mechanism of passenger boarding and alighting processes, as well as its potential influence on train dwell time and train operation. Empirical data collected from one of busiest metro stations in Seoul, Korea, demonstrates the spatial and temporal variation in the passenger service rate, as a result of interference between boarding, alighting, and standing passengers. This study postulates that the level of interference can be associated with the train car occupancy and the proximity of train door to entry points, as waiting passengers tend to cluster near the platform entries. A unique temporal service rate curve is derived from each door location. We introduce Dynamic Time Warping for similarity assessment and clustering. It revealed four groups of train doors showing distinct shapes of curve from each platform. The first cluster includes the train doors located closest to the platform entry points where the initial service rate is drastically impeded by severe inference among passengers. The level of interference gradually diminishes as the door is located farther away from the entry points, but the overall service rate decreases as well. A passenger service time model is derived to include the cluster variable. To test its significance, the prediction capability of the model is presented with and without the cluster variable. The results of this study may be used to guide waiting passengers along the platform to minimize interference and to avoid serious disruption during passenger service time.     

基于大规模定制延迟制造技术的时间模型及快速响应方法研究

本文通过大规模定制生产模式的论述，指出延迟制造技术是解耦大规模定制中时间、成本和个性化的矛盾问题的较好的解决方式，并对延迟制造技术进行了新的分类。针对大规模定制的快速响应问题，提取了面向大规模定制的时间模型并进行了分析；最后指出大规模定制快速响应问题的解决方案是基于延迟制造基础上的可重组制造系统。     

旅游生态系统及其要素配置结构

旅游生态系统是生态旅游区自然生态要素与旅游经济社会要素复合而成的复杂体系,快速增长的生态旅游需求与自然生态环境供给相对不足的矛盾构成了该系统的基本矛盾.文章认为,为了确保生态安全和促进生态旅游的可持续发展,必须坚持生态旅游利益相关者的互惠共生,创新生态旅游区的"小众旅游"模式,保障区域内自然生态要素与旅游经济社会要素协同运转和实现旅游生态系统的立体网络化布局.     

吉林省国有企业资本结构分析及优化对策

吉林省国有企业资本结构中,普遍存在资产负债率过高、国有股比例偏大现象。企业资本结构与多方面的因素相关。吉林省国有企业在收益质量、收入增长率方面较薄弱,导致资本结构不合理,应从产权制度和公司治理入手,通过制度创新,在加大股权融资、提高收益质量和收入增长率等方面采取措施,以优化资本结构。     

论优化产业集群发展环境中政府职能的发挥

产业集群是扩大产业规模、提升产业核心竞争力、形成区域特色经济的最有效途径之一,也是推动经济转型、促进经济又好又快发展的重要策略选择。同时,必须克服产业集群内部自身存在的缺陷。为此,必须进一步转变政府职能,发挥政府在集群风险中预防与干预作用,优化产业集群发展环境,推动地方产业转型与升级的健康发展。     

Portfolio optimization based on GARCH-EVT-Copula forecasting models

This study uses GARCH-EVT-copula and ARMA-GARCH-EVT-copula models to perform out-of-sample forecasts and simulate one-day-ahead returns for ten stock indexes. We construct optimal portfolios based on the global minimum variance (GMV), minimum conditional value-at-risk (Min-CVaR) and certainty equivalence tangency (CET) criteria, and model the dependence structure between stock market returns by employing elliptical (Student-$t$ and Gaussian) and Archimedean (Clayton, Frank and Gumbel) copulas. We analyze the performances of 288 risk modeling portfolio strategies using out-of-sample back-testing. Our main finding is that the CET portfolio, based on ARMA-GARCH-EVT-copula forecasts, outperforms the benchmark portfolio based on historical returns. The regression analyses show that GARCH-EVT forecasting models, which use Gaussian or Student-$t$ copulas, are best at reducing the portfolio risk.     

生态文明理念下的河南省产业结构优化问题研究

通过对生态文明与产业结构关系的分析,指出了河南省生态文明建设和产业结构优化过程中存在的问题,认为用生态文明理念指导该省产业结构优化。加强生态文明教育,建立现代生态产业、增强产业技术创新能力、完善相关法律法规等,是优化河南省产业结构的必要途径。