森林保险支付意愿及影响因素分析——基于异质性营林主体视角

基于期望效用函数理论分析了异质性营林主体的森林保险支付意愿及差异,并以传统小林农和新型林业经营主体为研究对象,以福建省382户传统小林农和88户新型林业经营主体的调研数据为基础,综合运用条件估值法、卡方检验及Cox比例风险模型,对异质性营林主体的森林保险支付意愿与差异及支付意愿影响因素进行对比与分析。研究表明：传统小林农和新型林业经营主体的森林保险意愿支付水平存在显著差异,在1000~2500元/亩保障水平下,传统小林农的意愿支付水平分别为1.911元/亩、2.941元/亩、3.532元/亩及3.979元/亩,新型林业经营主体为1.632元/亩、3.971元/亩、5.809元/亩及6.864元/亩;两类营林主体的支付意愿均随保额的提高而提高,但新型林业经营主体的提升幅度远高于小林农。异质性营林主体的森林保险支付意愿影响因素也存在明显差别,这与其在森林保险认知特征、林业生产经营特征、林业灾损特征、森林保险产品评价特征等方面存在显著差异有关。此外,林地面积对两类营林主体支付意愿均具有显著影响,规模化、集约化的林业生产经营可促进林业经营主体的森林保险愿意支付水平。     

Electricity supply industry in North America

This paper describes the electricity supply system in the USA and Canada based on an analysis of the performance characteristics of the North America Electric Reliability Councils which regulate the interlinked generation capabilities of the two countries. It is shown that whereas the national average efficiency of production and delivery of electricity in the USA is 32%, the actual value varies between 22% and 47% depending on geographical location. For Canada, the range is 32% to 68% with a national average of 43%. A detailed analysis of the dependence of each area on the different primary fuels is also given.     

三普2#地热站供热工程设计方案优化分析

通过分析地热供热的相关概念，建立了高效利用地热能源的一系列实现途径。根据工程的基础材料，从技术和经济方面对单纯地热供热方案、地热燃气调峰方案、热泵配置方案以及最终的组合方案进行了优化和调整，从而为三普2#地热井供热工程提供了优化方案，提高了该地区的地热利用率。     

A “RATIONAL” POLICY FOR THE ENERGY AND ENVIRONMENTAL CRISES1

ABSTRACT: The present energy and environmental crises are due to increasing per capita demands as well as increasing populations. The role that traditional pricing policies have played in promoting these demands is discussed. The reduction or stabilizing of per capita demands is advocated through the use of Conservational Pricing mechanisms which charge higher average prices for high consumption. An example of the effect of Conservational Pricing in the water supply industry is given.     

跨世纪时期的世界矿产资源形势和我国的对策

本文研究分析了世界资源、尤其是矿产资源的供需形势,以及全球资源紧张与危机的状况和发展趋势。结合我国资源状况和国情,从经济、社会长期发展战略角度,论述了客观分析、参与研究国际及我国社会基础资源问题的重要性、紧迫性,并提出建立我国资源供需持续、稳定、协调发展的方略对策。     

PEAK PERIOD DESIGN STANDARDS FOR SMALL WESTERN U.S. WATER SUPPLY SYSTEMS1

ABSTRACT: In order to determine design capacities for various components of municipal and rural domestic water supply systems, engineers must estimate water requirements for an entire year (water rights), for the peak season (reservoir storage), for the peak day (pump or treatment plant size), and for peak hour (pipeline sizes). Historically, per capita water use rates have varied greatly between systems, particularly in semiarid regions where outdoor demands are large. The resulting uncertainty in design capacity estimates can cause either inadequate capacities or premature investment. In order to minimize that uncertainty multiple regression and frequency analyses were made of the various water demand parameters mentioned above for 14 systems in Utah and Colorado. Specifically, demand functions are reported for average month, peak month, and peak day. Peak hour demands were also studied but are reported in a different paper. The independent variables which were significant for monthly and daily demands were price of water and an outdoor use index which includes the effect of variation in landscaped area and accounts for use of supplementary ditch or pressure irrigation systems. The demand functions were developed with data from systems varying in size from very small low density rural systems to Salt Lake City's water system. The correlation coefficients (R²) vary from 0.80 to 0.95.     

COMPARATIVE EVALUATION OF STATISTICAL METHODS FOR WATER SUPPLY FORECASTING1

ABSTRACT: While the correlation coefficient and standard error of estimate are frequently used when comparing models of seasonal water yield, the following criteria may be more important in selecting one model from among several alternatives: rationality of the regression coefficients, the distribution of the residual errors, and the correctness of indicators of the relative importance of the predictor variables. These criteria were used to compare seasonal water yield models that were calibrated using multiple regression, stepwise regression, principal components regression, polynomial regression using a principal components rotation, and constrained pattern search. Hydrologic data from the Upper Sevier River basin in southern Utah were used to illustrate the comparative analysis process. The prediction equations used the April-July streamflow volume as the criterion variable.     

1985-2005年中国城市水源地突发污染事件不完全统计分析

对1985-2005年中国城市水源地突发污染事件进行了统计分析,以从总体上揭示这些事件的发生规律及其对城市水源地和供水安全的危害.采用文献检索方法,通过对1985-2005年<中国环境报>、<人民日报>、新华网等报刊和网络的检索,从发生日期、地点、污染物种类、事件简况4个方面统计中国城市水源地突发污染事件,经整理和筛选后共列出102起.这些突发污染事件的分析结果表明:1)中国城市水源地突发污染事件总体上呈数量逐年增多,危害增大的趋势;2)化学品和污水是主要污染物;3)河道交通事故和工厂泄漏事故是主要风险源;4)突发污染事件一般都造成了比较严重的经济社会影响,但缺乏相应的应急管理机制和应急部门;5)3个典型突发污染事件造成重大经济社会损失并引发社会高度关注,凸现了构建中国城市水源地突发污染事件应急机制的重要性和迫切性.     

pp´DDT and pp´DDE Accumulation in a Food Chain of Lake Maggiore (Northern Italy): Testing Steady-State Condition

- DOI: http://dx.doi.org/10.1065/espr2006.01.010 Background, Aims and Scope Although pp'DDT usage was strongly limited or banned in most parts of the world during the last three or four decades, the parent compound, its homologues and their metabolites still occur at levels which might pose a risk for many ecosystem components. A case of DDT pollution of industrial origin was discovered in 1996 in Lake Maggiore, the second largest (212 km2) and deepest (370 m) lake in Italy, causing concern for wildlife and human health. The extensive monitoring of many biotic and abiotic compartments which followed from 1998 in order to assess the pollution level and its trend in time, provided a great availability of data referring to DDT contamination of the different fish species of the lake. In this study, the recent contamination levels in selected fish species were compared to those measured in 1998 to evaluate the temporal pollution trend of the lake and its natural recovery, given that no remediation measures were carried out on the contaminated soils and sediments in this time span. Moreover, a modelling approach to test the equilibrium condition between water and pelagic fish species was used. Analytical results of pp'DDT and pp'DDE concentrations in lake water were used as input data in the bioenergetic model by Connolly & Pedersen (1988) to calculate concentrations in two fish species and to compare the predicted and the measured contamination. Methods Sampling and analytical determination of DDT homologues in lake water: Five water sampling campaigns were carried out from May 2002 to February 2004 in three sampling sites of Lake Maggiore. Suspended and dissolved pollutants were determined separately. Quantitative DDT homologue analyses were performed by HRGC coupled with ECD detection by the external standard method. Single water extracts were put together in correspondence with the stratification zones of the water column inferred on the basis of the temperature profile to improve analytical sensitivity. Selection of fish data: Concentrations of DDT and DDE in fishes were selected from recent literature (CIPAIS 2003, 2004). Bioaccumulation model: The bioenergetic model proposed by Connolly & Pedersen (1988) was used to assess the bioaccumulation of pp'DDT and pp'DDE of Alosa fallax (landlocked shad) and Coregonus spp. (whitefish), selected among the different species as representative of a secondary consumer level. Results and Discussion The average concentrations of pp'DDT and pp'DDE in water to be used as input data in the bioenergetic model were obtained considering all the concentrations measured at the three sampling stations in the epylimnion where the fish species considered in this study spend most of their life. The resulting values were 0.05 and 0.16 ng/L for pp'DDT and pp'DDE, respectively. Average measured pp'DDT and pp'DDE concentrations in landlocked shad were 0.81 +/- 0.39 and 1.69 +/- 0.71 mg/kg lipids, respectively, and were 0.29 +/- 0.12 and 1.06 +/- 0.41 mg/kg lipids for the whitefish. Calculated and measured values turned out to be in quite good agreement for pp'DDT, while measured pp'DDE concentrations were higher than expected on the basis of the bioenergetic model in both species. Probably metabolic transformations of pp'DDT accumulated in fish tissues in the past are responsible for the observed differences between calculated and expected pp'DDE concentrations in fish. Conclusions Pelagic fishes of Lake Maggiore seem to maintain the DDT accumulated during their life time and the most efficient mechanism responsible for the fish population recoveries is probably their generation changes; for this reason, equilibrium models cannot be used until negligible pp'DDT concentrations are reached in fish tissues. Recommendations and Outlook The limit proposed for pp'DDT in water by the EU Directive 2000/60, which will come in force in 2008, is 0.2 ng/L, four times higher than the average concentration measured in Lake Maggiore waters. Nevertheless, concentrations measured in Lake Maggiore fish were very close and sometimes exceeded the Maximum residue limits (MRLs) settled by the Italian legislation for foods (0.1 mg/kg w.w. for fish containing 5–20% lipid). It seems, therefore, that the 'environmental quality standard' of 0.2 ng/L cannot guarantee the suitability of fish for human consumption.     

建筑应急照明的设计与施工探讨

应急照明是现代建筑安全保障的重要设施之一,它同人身安全和建筑物安全紧密相关。根据建筑电气设计规范对应急照明的具体规定,对应急照明的设计要求做了进一步探讨和归纳总结,并结合具体问题对应急照明设置场所、供电时间、电源供电方式、控制方式、施工设计及设计要点等方面进行了阐述,对应急照明的设计和实践应用中出现的问题进行了分析,并提出了整改措施。