小流域水分行为、生态效应及其优化调控研究方面的若干问题

把小流域水文生态研究,分解为小流域水分行为、生态效应及其优化调控研究3个方面。在分析国内外研究现状与问题的基础上,指出了其需要系统加以探讨的若干内容,认为由此可构建流域水文生态学的基本框架,进而发展流域水文生态学。     

1985-2015年京津冀地区城市建设用地时空演变特征及驱动因素研究

长期以来土地利用/覆被变化一直是全球关注的热点话题,研究城市建设用地时空演变特征,准确定位城市功能是促进城市科学、持续发展的重要保障。以京津冀地区13个城市1985-2015年的城市建设用地为研究对象,运用定量与定性结合的方法,分析城市建设用地时空演变特征;利用多元线性回归、通径分析、地理探测器等方法,诊断城市建设用地时间演化过程与空间演变格局分异的主导驱动因子,通过深入分析各主导因子的驱动机制,对京津冀的城市发展进行功能定位。结果表明：① 京津冀地区城市建设用地的扩张规模、速率、方向和稳定性等存在明显的差异,将城市类型分为协调稳定型、协调波动型、不协调稳定型、不协调波动型;② 城市建设用地时间演化过程的主导驱动因子包括GDP指数、人口密度指数、财政收入指数,空间演变格局差异的主导因子包括到城市中心距离、到主要河流距离、到主要公路距离;③ 根据分析结果,将京津冀地区13个城市规划为核心经济引领城市、重点经济拓展城市和稳定经济涵养城市,对促进京津冀地区协调统筹和一体化发展具有参考价值。     

The life cycle of contributors in collaborative online communities -the case of OpenStreetMap

Over the last two decades, online communities have become ubiquitous, with millions of people accessing collaborative project websites every day. Among them, the OpenStreetMap project (OSM) has been very successful in collecting/offering volunteered geographic information (VGI). Very different behaviours are observed among OSM participants, which translate into large differences of lifespan, contribution levels (e.g. Nielsen’s 90–9-1 rule) and attitudes towards innovations (e.g. Diffusion of innovation theory or DoIT). So far, the literature has defined phases in the life cycle of contributors only based on the nature of their contributions (e.g. role of participants and edits characteristics). Our study identifies the different phases of their life cycle from a temporal perspective and assesses how these phases relate to the volume and the frequency of the contributions from participants. Survival analyses were performed using both a complementary cumulative distribution function and a Kaplan-Meier estimator to plot survival and hazard curves. The analyses were broken down according to Nielsen and DoIT contributors’ categories to highlight potential explanatory variables. This paper shows that two contribution processes combine with three major participation stages to form six phases in contributors’ life cycle. The volume of edits provided on each active day is driven by the two contribution processes, illustrating the evolution of contributors’ motivation over time. Since contributors’ lifespan is a universal metric, our results may also apply to other collaborative online communities.     

Effectiveness of pilot carbon emissions trading systems in China

China is in the process of establishing a national emissions trading system (ETS). Evaluating the implementation effectiveness of the seven pilot ETSs in China is critical for designing this national system. This study administered a questionnaire survey to assess the behaviour of enterprises covered by the seven ETS pilots from the perspective of: the strictness of compliance measures; rules for monitoring, reporting and verification (MRV); the mitigation pressure felt by enterprises; and actual mitigation and trading activities. The results show that the pilot MRV and compliance rules have not yet been fully implemented. The main factors involved are the lack of compulsory force of the regulations and the lack of policy awareness within the affected enterprises. Most enterprises have a shortage of free allowances and thus believe that the ETSs have increased their production costs. Most enterprises have already established mitigation targets. Some of the covered enterprises are aware of their own internal emission reduction costs and most of these have used this as an important reference in trading. Many enterprises have accounted for carbon prices in their long-term investment. The proportion of enterprises that have participated in trading is fairly high; however, reluctance to sell is quite pervasive in the market, and enterprises are mostly motivated to trade simply in order to achieve compliance. Few enterprises are willing to manage their allowances in a market-oriented manner. Different free allowance allocation methods directly affect the pathways enterprises take to control emissions.

Key policy insights

• In the national ETS, the compulsory force of ETS provisions should be strengthened.

• A reasonable level of free allowance shortage should be ensured to promote emission reduction by enterprises.

• Sufficient information should be provided to guide enterprises in their allowance management to activate the market.

• To promote the implementation of mitigation technologies by enterprises, actual output-based allocation methods should be used.

• The government should use market adjustment mechanisms, such as a price floor and ceiling, to ensure that carbon prices are reasonable and stable, so as to guide long-term low carbon investment.

     

考虑内定向误差的外方位元素精度分析

在对数据质量的要求越来越严格的今天,我们对数据质量的评价也必须越来越系统、可靠。本文就是在系统分析的基础上推导出了求解外方位元素的误差传递模型,并从中分析了内定向误差对外方位元素精度的影响,从而改进和完善了外方位元素精度的评定方法,使得外方位元素精度的评定具有更高的精确性和可靠性。     

裂隙参数分析在岩体力学和水力学习性研究中的应用

岩体的力学和水力学习性主要取决于其中裂隙的发育程度。一定成因的裂隙具有一定的发育规律,这一规律既具确定性又具随机性。本文详细讨论了表示岩体裂隙发育程度特征参数的量测和分析方法,重点论述了裂隙参数分析在研究岩体渗透习性、岩体中裂隙网络计算机模拟及岩体弹性参数分析等方面的应用。     

斜长石组构的显微测量方法及应用

介绍了目前国外用费氏台测量斜长石组构的三种方法：（１）ＢＰＷ图解法;（２）（０１０）,（００１）双面交点法;（３）（０１０）消光角法;并分析了其适用范围及各自的优缺点。最后总结了确定斜长石组构的应用意义;（１）确定滑移系;（２）判断剪切方向;（３）计算地震波速。     

数字相机在类似棋盘检校场中的检校方法研究

针对众多非量测单相机的检校方法,通过分析数码相机的误差来源,并考虑相机的内、外方位元素和物镜光学畸变等因素引起的误差,提出一种基于类似棋盘检校场的数字相机检校方法。利用共线方程和二维DLT之间的关系导出了由二维DLT的9个参数表达的主纵线方程,构建同形矩阵,通过不同摄站拍摄目标的多幅影像,求得内、外方位元素的初始值,并由多张影像的空间后方交会求出相机需要检校参数,再由假设检验来检验相机系统参数的显著性。经实例分析表明,利用改进后的方法求解参数的精度满足实际需求,且效率更高。     

单晶高温合金X射线衍射斑点自动识别算法研究

单晶高温合金展现出优越的抗疲劳性能和高温蠕变性能,广泛应用于航空发动机和燃气轮机的热端部件。但是,其制备过程中会产生晶体取向偏离、杂晶等缺陷。目前国际上已经普遍使用X射线劳埃衍射技术对单晶叶片的晶体缺陷进行无损检测,但是这种检测方法主要依赖人工识别,效率低,结果可重复性差,不适合批量化检测。本文结合工程需要,提出对劳埃衍射斑点进行自动识别的算法,主要包括衍射图样的预处理、轮廓检测、轮廓形态筛选及轮廓符合检测等。该算法能够自动检测出衍射图样上的衍射斑点,并最终给出斑点的位置坐标数据及其误差。根据衍射斑点的位置,通过衍射分析算法,计算出单晶叶片上的晶体取向,并最终对叶片的晶体缺陷给出综合评价。