甘肃省酒泉市土地沙漠化现状及动态分析

[目的]沙漠化是酒泉市面临的主要生态环境问题之一,了解土地沙漠化现状,分析其动态演变特征,是维持区域生态安全,保证经济社会可持续发展的关键前提。[方法]研究依托GIS技术,结合最新卫星影像数据,采用野外调查和人机交互解译的方法,对酒泉市沙漠化土地面积、类型、程度进行了监测,同时通过对比酒泉市上期(2009年)沙漠化土地监测数据,分析了沙漠化土地的动态特征和变化原因。[结果]酒泉市现有沙漠化土地面积956.34万hm~2,较2009年减少了4.07万hm~2,年变化率-0.08%,呈整体减少趋势;沙漠化程度以重度和极重度为主,但整体呈减轻趋势,具体表现为重度沙漠化土地面积减少7.87万hm~2,年变化率-0.75%,极重度沙漠化土地面积减少19.47万hm~2,年变化率-0.64%。沙漠化土地类型以流动沙地(丘)、半固定沙地(丘)、固定沙地(丘)和戈壁为主,占沙漠化土地面积的98.16%。[结论]降水和地表径流的增加、生态工程的实施、水资源利用集约化、关井压田工程的开展以及基础设施建设是酒泉市沙漠化土地面积减少的主要原因。     

中国绿色建筑面积时空演化及驱动机制研究

基于中国绿色建筑面积的面板数据,运用差异指数、自然断裂点法、空间自相关分析研究绿色建筑面积的时空演化,建立固定效应面板数据模型分析绿色建筑面积空间分布格局的驱动机制。结论如下:(1)绿色建筑面积绝对差异呈增大趋势,相对差异呈缩小趋势;(2)我国绿色建筑面积的演化以路径依赖型为主,处于低水平区和中低水平区的省域数量较多;(3)绿色建筑面积存在显著的正空间自相关性,低低聚集状态为主,形成以浙江、安徽、上海以及江苏为核心,向相邻省域扩散的高值热点区域,低值冷点区域则呈向西北扩散趋势;(4)绿色建筑面积空间格局的形成是经济核心驱动、人口直接驱动、政策外部驱动、自然基础驱动和市场内部驱动共同作用的结果。     

Multiobjective optimization of asphalt pavement design and maintenance decisions based on sustainability principles and mechanistic-empirical pavement analysis

Highway pavement as an important component of transport infrastructure has significant impacts on economy, society, and environment. The management of highway pavement has been traditionally focused on economy. In this study, the impacts of management decisions are examined in three dimensions, including life-cycle cost (LCC), energy consumption, and greenhouse gas (GHG) emissions. Quantitative models to predict the three dimensions are developed from mechanistic-empirical pavement analysis results. Two decision variables, pavement thickness and threshold roughness level for pavement resurfacing, are found to be significant in affecting the three dimensions. These two variables are subsequently used as decision variables in multiobjective optimization. The ranges of decisions that result in minimum LCC, energy consumption, and GHG emissions are identified through multiobjective optimization. Although the analysis is illustrated in the context of pavement design and management in Hong Kong, the analysis techniques and procedures can be easily applied in other regions.     

A Better Understanding of Granger Causality Analysis: A Big Data Environment

This paper aims to provide a better understanding of the causal structure in a multivariate time series by introducing several statistical procedures for testing indirect and spurious causal effects. In practice, detecting these effects is a complicated task, since the auxiliary variables that transmit/induce indirect/spurious causality are very often unknown. The availability of hundreds of economic variables makes this task even more difficult since it is generally infeasible to find the appropriate auxiliary variables among all the available ones. In addition, including hundreds of variables and their lags in a regression equation is technically difficult. The paper proposes several statistical procedures to test for the presence of indirect/spurious causality based on big data analysis. Furthermore, it suggests an identification procedure to find the variables that transmit/induce the indirect/spurious causality. Finally, it provides an empirical application where 135 economic variables were used to study a possible indirect causality from money/credit to income.     

顾客资产管理战略地图的构建

分析了顾客资产管理兴起的驱动因素,回顾和梳理了当前的顾客资产管理模型,结合平衡计分卡理论,构建了顾客资产管理的战略地图,并分析了顾客资产管理的未来研究主张。     

Stochastic growth with social-status concern: The existence of a unique stable distribution

This paper extends Kurz’s (1968) growth model to a stochastic growth framework with social-status concern and unbounded production shocks. Using the stochastic monotonicity of a stochastic dynamic system and the methods adopted in Zhang (2007), the existence, uniqueness, and stability of invariant distribution are investigated. Different from the existence of multiple steady states under certainty, it is shown here that there exists a unique stable invariant distribution under uncertainty.     

基于因子分析的区域制造业竞争力研究——以山东省为例

文章采用因子分析法对山东省制造业30个行业的竞争力相对全国平均水平进行了综合评价,结论表明目前山东省制造业整体发展水平处于劳动密集型产业向资本密集型产业过渡阶段,具有竞争优势的产业以传统的劳动密集型产业为主,支柱产业以及重点发展产业的产业聚集度还不高,规模经济效应不明显。     

19世纪美国史视角下的奥姆斯特德及其 设计思想

立足奥姆斯特德的书信、报告等史料文件,聚焦到 奥姆斯特德与19世纪美国文明转向、文化独立及阶层政治相 关的具体事件,层层重构这些事件的风景园林学意义。再通过 分析纽约中央公园,检视奥姆斯特德价值观念的呈现。致力于 建构奥姆斯特德设计思想、价值判断及空间理念等方面内容与 19世纪美国史之间的脉络性关联,以期推动风景园林学科中 的空间理解与社会、政治之间建立互动关系。     

Using Available-for-sale Securities to Smooth Earnings: Evidence from China

Utilizing a large sample of non-financial public firms in China from 2009 to 2016, we find robust evidence that non-financial firms smooth their earnings through realized gains and losses on available-for-sale (AFS) securities. This effect is more pronounced for firms with weaker internal and external corporate governance. Firms with an incentive to manipulate up their earnings are also less likely to smooth earnings through AFS securities. Moreover, firms with more accrual earnings management or real earnings management tend to smooth earnings to a greater extent through AFS securities. Firms smooth earnings only when their net income is positive or when net income is negative and the gains from AFS securities are large enough to offset negative earnings. We do not find supporting evidence for engaging in big bath earnings management through the realization of losses on AFS securities. These findings suggest that gains and losses on AFS securities allow non-financial firms to actively smooth their earnings. Last, the accounting standards amendments in 2017 that essentially disable earnings smoothing through AFS securities increase price efficiency.