大型测控设备的接地系统设计与探讨

介绍了接地的目的和种类,针对大型测控设备对接地电阻值的要求,提出了区域面积受限的接地系统设计方案,并对接地电阻进行了详细分析、计算和比较,选出了合理的接地方案进行施工,竣工后对接地系统的接地电阻值进行检测,检测结果满足测控设备接地电阻的要求.     

建筑抗震设计地震作用折减系数的取值方法

地震作用折减系数在建筑抗震设计中是政策性、技术性和经济性的综合指标。本文以钢筋混凝土框架结构为例,从技术上介绍了地震作用折减系数的确定原则。在简要介绍我国建筑抗震设计规范设计地震作用—延性等级组合运用中存在不足的基础上,论述了地震作用折减系数三个分量的基本特点,并分四个步骤介绍了其计算取值方法。推荐方法可为建筑抗震设计确定合理的地震作用折减系数提供有益的参考。     

Multi-response optimization of Fenton process for applicability assessment in landfill leachate treatment

Fenton process, as a pretreatment method, was found to be effective in the primary treatment of mature/medium landfill leachate. However, the main problem of the process is the large amount of produced sludge that requires an accurate feasibility evaluation for operational applications. In this study, the response surface methodology was applied for the modeling and optimization of Fenton process in three target responses, (1) overall COD removal, (2) sludge to iron ratio (SIR) and (3) organics removal to sludge ratio (ORSR), where the latter two were new self-defined responses for prediction of sludge generation and applicability assessment of the process, respectively. The effective variables included the initial pH, [H₂O₂]/[Fe²⁺] ratio and Fe²⁺ dosage. According to the statistical analysis, all the proposed models were adequate (with adjusted R² of 0.9116–0.9512) and had considerable predictive capability (with prediction R² up to 0.9092 and appropriate adequate precision). It was found that all the variables had significant effects on the responses, specifically by their observed role in dominant oxidation mechanism. The optimum operational conditions obtained by overlay plot, were found to be initial pH of 5.7, [H₂O₂]/[Fe²⁺] ratio of 17.72 and [Fe²⁺] of 195 mM, which led to 69% COD removal, 2.4 (l sludge/consumed mole Fe²⁺) of SIR and 16.5 (gCOD removed/l produced sludge) for ORSR in verification test, in accordance with models-predicted values. Finally, it was observed that [H₂O₂]/[Fe²⁺] ratio and Fe²⁺ dosage had significant influence on COD removal, while Fe²⁺ dosage and [H₂O₂]/[Fe²⁺] ratio had remarkable effects on SIR and ORSR responses, respectively.     

Earthquake risk reduction: An examination of local regulatory efforts

We develop an understanding of local governmental efforts to address earthquake risks. Our data for a sample of California and Washington cities' risk-reduction efforts sort into two different clusters of leading jurisdictions as contrasted with a cluster of lagging jurisdictions. We explain differences among the three categories of cities in terms of different political-economic factors. Local governmental willingness and ability to undertake risk-reduction programs have more to do with local political demands and community resources than with objective risk or previous earthquake experience. State mandates have a selective impact on local risk-reduction efforts. The principal policy lessons concern the need to address gaps in local risk-reduction efforts through more careful targeting of federal and state earthquake programs and by including stronger teeth within state mandates.     

江苏省近40年洪涝灾害概况及防洪对策

本文分析了江苏省４０ａ来洪涝灾害概况及１９９１年特大洪涝受灾情况。针对江苏实际，提出了减灾对策。     

铁屑还原－鼓风氧化－石灰凝沉法脱除硫酸生产废水中的砷

比较了硫酸生产废水的几种除砷方法，认为铁屑还原－鼓风氧化－石灰凝沉工艺是可行的，此法具有处理量大、处理效果好、运行费用低等优点。     

国外减轻城市洪涝灾害新设施发展综述

近二十多年国外在减轻城市洪涝灾害设施方面发展很快,建造了各种新型的抑制暴雨径流的设施,可分为流域雨水贮留设施和流域雨水渗透设施两大类,本文主要介绍目前国外已经建成和计划兴建的这些设施的型式、规划设计步骤、引起的问题和管理维护方法,以及在我国发展这些设施的必要和可能。     

干旱对电力生产的影响

本文以１９９４年～１９９５年干旱对陕西省电力生产的影响为例，论述了干旱对电力生产的影响，在此基础上提出了相应的减灾对策．     

泥石流突变模型

本文在崔鹏的泥石流实验工作的基础上，用柘扑变换的方法建立了一个泥石流突变模型；并分析了泥石流的突变条件和机制；从理论上指出了防治泥石流发生和减轻泥石流灾害的措施，这在设计防治泥石流工程上将具有指导意义。     

Waste reduction through variable charging programs: its sustainability and contributing factors

 In this study, we analyzed the sustainability and determinant factors of waste reduction through variable charging schemes. We drew three main conclusions from the study. (1) Waste reduction was achieved by variable charging and was sustained over an average of at least 10 years. The results regarding the sustainability of the price effect were inconclusive. (2) The main factors contributing to the combustible waste reduction achieved through variable charging were two-tier pricing and the price of waste bags. The effect of two-tier pricing programs was positive. (3) Waste paper recycling and variable charging reinforce each other to promote waste reduction. Received: September 3, 2001 / Accepted: January 13, 2002