初始浓度分布对一维含水层中溶质运移的影响

为了研究含水层中任意初始浓度分布条件下一维含水层介质中的溶质运移规律,采用对流-弥散方程构建考虑任意初始浓度分布条件下一维含水层介质中溶质运移动力学数学模型,模型采用持续注入示踪剂、瞬时注入示踪剂和脉冲注入示踪剂3种不同的边界条件,数学模型的求解采用格林函数法.并通过开展室内一维砂柱实验进一步验证模型的科学性和适用性....     

Use of the Contingent Valuation Method in the assessment of a landfill mining project

A comprehensive approach for the evaluation of the economic feasibility of landfill mining (LFM) should take into account not only the direct costs and revenues for the private investor, but also the social benefits or costs (generally called externalities), in such a way that projects generating major social benefits (and no significant private revenues) are not overlooked.With a view to contributing to the development of a common framework for the evaluation of LFM projects, this paper presents the results of a case study where the issue of the assessment of social benefits from a LFM project is addressed. In particular, the Contingent Valuation Method is applied for the monetary assessment of the community-perceived benefits from the remediation of an old uncontrolled waste deposit by means of LFM and the conversion of the area into a park.Based on the results of a survey carried out on a random sample of people living near the old landfill, the economic values of the individual willingness to pay (WTP) for LFM and the subsequent creation of a public park were calculated and the correlations with the relevant variables (distance from the landfill site, age, income, sex, education level) assessed. The results were then suitably extended and the monetary value of the welfare increase of the whole population resident in the area and potentially affected both by LFM and the creation of the park was calculated.     

Factors influencing NOx emission of a stationary diesel engine fuelled with crude rice bran oil methyl ester blend – Taguchi approach

The main objective of this work is to control the NO_x emission of a stationary diesel engine fuelled with crude rice bran oil methyl ester blend with less sacrifice on smoke density and brake thermal efficiency (BTE) and also to investigate the factors influencing the objective. Fuel injection timing, percentage of exhaust gas recirculation and fuel injection pressure are chosen as the promising factors for the objective and NO_x emission, smoke density and BTE are considered as response variables. Tests were conducted as per Taguchi’s L₉ orthogonal array and the most influencing factor for each response variable and also the significance of each factor on the same was found out through analysis of variance (ANOVA). Response graph was drawn for each response variable and from the results of response graph and ANOVA the optimum combination of the factor levels in achieving the objective was obtained and the same was confirmed experimentally.     

环滇池区域经济发展中水源地居民的补偿问题探讨

分析了松华坝水源地水源保护政策的效果和农民人均年纯收入水平，认为需建立补偿机制。提出了将原水销售中的部分收入反馈到水源地和往用水城市搬迁移民等补偿方式。     

基于CHNS的中国城乡居民的食品消费特征——兼与国家统计局数据对比

基于2011年我国12个省（直辖市）的中国健康与营养调查数据（China Health and Nutrition Survey, CHNS）,文章利用食物成分表重新估算我国城乡居民主要食品的消费量及在外消费特征,并与国家统计局公布的官方数据进行对比。结果显示：1）口粮方面,2011年我国居民平均消费口粮量为119.93 kg,外出消费比例为9.91%。2）肉蛋奶类方面,2011年我国人均肉类消费量（猪牛羊禽）为32.84 kg,其中,猪肉消费量占69.85%,禽肉消费量占20.98%,牛羊肉消费量偏低,为9.20%。我国居民平均还消费蛋类10.90 kg、奶类13.56 kg。3）我国城镇居民口粮消费明显低于农村居民,肉蛋奶消费量明显高于农村居民,但农村居民肉蛋奶在外消费的比例要高于城镇居民。4）国家统计局公布的肉蛋奶数据整体上偏低,农村消费数据的偏低程度尤为严重,重点体现在鲜蛋、水产品与鲜奶产品上。国家统计局公布的食品消费数据多与CHNS数据的家庭内部消费数据相吻合,其数据偏小的原因可能是由于缺失户外消费数据的统计。从消费数量上来看,预计今后我国居民口粮消费量的下降空间已经非常有限,但肉蛋奶消费水平仍有较大的抬升空间,农业的生产压力与畜牧饲料大量进口的局面将持续存在。     

Evaluation of beach quality as perceived by users

Recreational beaches are strategic ecosystems for tourism and should be used in a sustainable manner. We studied three beaches in the municipality of Guaymas (NW Mexico), in order to assess their beach quality and identify key management issues. The evaluation was based on the perceptions of users concerning: (1) the user profile; (2) the recreational habits of users; and (3) the biophysical characteristics, infrastructure, services, and cleanliness of each beach. The results showed that the beaches were of different quality. The key management issues identified were the need to design and apply specific management programs for each beach, specifically in regards to improving infrastructure and services, and obtaining certification as a sustainable beach. The evaluation of the beaches as perceived by users suggests that it would be useful to assess beach quality in order to support management goals and be applicable to other beaches, both nationally and internationally.     

城市居民低碳消费行为的研究

21世纪充满着挑战，当世界上还有许多国家需要解决基本的生存问题之时，又要面对过去因单一的经济利益驱动而过度开发带来的环境问题、温室效应问题、资源危机问题等，人类要继续发展下去，就必须面对并尽可能解决这些问题。就解决温室效应问题而引出的低碳消费话题进行了一次调查问卷。调研获得的相关数据的结论，有助于南京市政府职能部门采取相应政策和措施，这样就可以引导南京市居民树立低碳消费理念，使南京市居民实施低碳消费行为。     

雾霾时车辆尾气排放对驾驶员能见度的影响

针对北京道路车辆尾气排放对雾霾时驾驶员道路能见度的影响问题,建立了雾霾时车辆尾气排放与驾驶员道路能见度关系模型。该模型以车辆为单元建立车辆尾气排放元胞,考虑了车辆尾气排放后的污染物物理和化学变化,并以车道中的尾气排放位置截面及截面单元、交叉口处的尾气排放位置区间为模型单元。为验证该模型,于2016年10月-2017年2月和2017年10月-2018年2月,在北京地区部分路网检测了驾驶员道路能见度等数据,并统计了各时段驾驶员道路能见度的分布情况。对建立的关系模型进行仿真,结果表明,该关系模型的仿真结果与实际检测数据的误差占比平均值小于4. 98%,验证了该关系模型用于描述北京市道路车辆尾气排放对雾霾时驾驶员道路能见度影响的有效性。