中国富营养化湖泊的生物修复

描述了中国湖泊富营养化污染现状 ,论述了湖泊富营养化形成的机理、生物修复富营养化湖泊 (尤其是去除水体和底泥碳、氮、磷 )的理论依据 ;提出了修复湖泊富营养化的技术途径 ,阐明了笔者对机械清淤和生物修复各自具有的优势和缺陷的看法。     

纯铜薄板矩形盒拉深特性的试验研究

作为非回转对称成形试验研究的一部分,进行了大量的矩形盒拉深试验。指出纯铜薄板的各向异性对矩形盒拉深成形性的影响不十分显著。增大凸模形状参数rc/w,成形中法兰短边和曲边材料向凹模口的流入速度减小,曲边变形加工度增大,是使成形极限降低的原因之一。rc/w=0.1附近,极限成形高度hmax最大。     

Bicycle helmet effectiveness is not overstated

Objective: The objective of this study was to discuss the challenges in estimating bicycle helmet effectiveness from case–control studies of injured cyclists and to estimate helmet effectiveness from cases and available exposure data.

Methods: Data were extracted from studies of cyclists in Seattle; Victoria and New South Wales, Australia; and The Netherlands. Estimates of helmet use were used as exposure to compute relative risks for Seattle and Victorian data. Cycling distance data are routinely collected in The Netherlands; however, these data cannot be disaggregated by helmet use, which makes it unsuitable for estimating helmet effectiveness. Alternative controls were identified from larger cohorts for the Seattle and New South Wales cases.

Results: Estimates of helmet effectiveness were similar from odds ratios (ORs) using hospital controls or from relative risks (RRs) using helmet use estimates (Seattle: OR = 0.339, RR = 0.444; Victoria: OR = 0.500, RR = 0.353). Additionally, the odds ratios using hospital controls were similar when controls were taken from a larger cohort for head injury of any severity (Seattle: OR = 0.250, alt OR = 0.257; NSW: OR = 0.446, alt OR = 0.411) and for serious head injury (Seattle: OR = 0.135, alt OR = 0.139; NSW: OR = 0.335, alt OR = 0.308). Although relevant exposure data were unavailable for The Netherlands, the odds ratio for helmet effectiveness of those using racing, mountain, or hybrid bikes was similar to other estimates (OR = 0.371).

Conclusions: Despite potential weaknesses with case–control study designs, the best available evidence suggests that helmet use is an effective measure of reducing cycling head injury.     

城市污水处理厂生物泡沫的案例分析及控制研究

通过对天津市两座污水处理厂生物泡沫的情况进行分析发现,丝状菌是形成生物泡沫的直接原因,而进水水质冲击、水温、泥龄、气水比是诱发丝状菌快速增殖的主要因素。控制措施有喷洒水等物理方法和投加药剂等化学方法,但实践证明合理调整工艺运行方式是预防和控制生物泡沫的根本手段,例如降低污泥龄、提高生物池的有机负荷率、降低曝气的空气量等方法。     

建设项目碳排放评价技术方法及案例研究

将碳排放因素纳入建设项目环评,对其进行项目层面的控制,有利于促进碳减排和低碳经济的发展。文章尝试构建了建设项目碳排放环评体系,通过对某污水处理厂工艺流程中的碳源分析,确定评价范围,核算情景年份下的碳排放量,综合分析碳排放对环境、经济及社会的影响,最后探讨了协同减排效应,并制定跟踪评价计划。研究表明该污水处理厂在情景年份下,随着污水处理量的增加,碳排放量逐年上升。     

Theoretical and Empirical Study on Urban Population Cawing Capacity： Case of Haidian District in Beijing

The measurement of urban population carrying capacity is the basis for cities＇ sustainable development. However, the traditional study on population carrying capacity which was based on food supply is not applicable to the single urban area. This paper built a model for the analysis of urban carrying capacity, and took Haidian District in Beijing as an example to calculate the urban carrying capacity of Haidian District in the future, which was the basis for the improvement of the population carrying capacity. This study would also provide a reference to the measurement of the urban population carrying capacity for other cities and districts in China.     

Theoretical and Empidcal Study on Urban Population Carrying Capacity:Case of Haidian District in Beijing

The measurement of urban population carrying capac- ity is the basis for cities' sustainable development.However,the traditional study on population carrying capacity which was based on food supply is not applicable to the single urban area.This paper built a model for the analysis of urban carrying capacity, and took Haidian District in Beijing as an example to calculate the urban carrying capacity of Haidian District in the future,which was the basis for the improvement of the population carrying capac...     

Integration of Case Studies on Global Change by Means of Qualitative Differential Equations

We present a novel methodology to integrate qualitative knowledge from different case studies on Global Change related issues into a single framework. The method is based on the concept of qualitative differential equations (QDEs) which represents a mathematically well-defined approach to investigate classes of ordinary differential equations (ODEs) used in conventional modeling exercises. These classes are defined by common qualitative features, e.g., monotonicity, signs, etc. Using the QSIM-algorithm it is possible to derive the set of possible solutions of all ODEs in the class. By this one can formulate a common, qualitatively specified cause–effect scheme valid for all case studies. The scheme is validated by testing it against the actually observed histories in the study regions with respect to their reconstruction by the corresponding QDE. The method is outlined theoretically and exemplary applied to the problem of land-use changes due to smallholder agriculture in developing countries. It is shown that the seven case-studies used can be described by a single cause–effect scheme which thus constitutes a pattern of Global Change. As a generally valid prerequisite for sustainability of this kind of land-use the presence of wage labor is shown to represent a decisive factor. This revised version was published online in July 2006 with corrections to the Cover Date.     

城市轨道交通危险因素分析

目前我国的城市轨道建设已经进入高潮期,城市轨道的安全问题也变得日益重要.笔者通过统计分析国内外历年发生的轨道交通事故,总结了轨道交通在施工期间、供电系统、车辆系统、通风/排烟系统、给/排水系统、通信/信号系统、公用工程及辅助设施等方面的事故分析了存在的危险因素,为确保地铁的安全运营提供依据.     

我国自然资源市场体系的建立与发展

文章以“东阳卖水—义鸟买水”这起全国首例水权交易的案例说明，必须清晰地界定自然资源的产权，同时减少有关自然资源交易过程中的费用，以尽快建立自然资源市场体系，发挥市场在配置自然资源方面的基础性作用。