Analysing the Diversity of Water Pricing Structures: The Case of France

This paper presents the results of a 2003 national survey of urban water pricing structure implemented by 429 district level water utilities. After providing some background elements on the diversity of existing water pricing structures, the paper shows how each structure can be used to achieve different management objectives (water allocation efficiency, costs recovery, and equity). It then describes the structures adopted by French water utilities, showing that flat rate are rarely adopted; declining blocks frequently used; and increasing blocks pricing which should be used to promote water use efficiency remain extremely rare. A statistical clustering is then conducted and a typology of situations elaborated. The paper concludes with highlighting that current pricing structures are influenced by past practices and that the dominant objective of water utilities is to cover costs.     

厦门市供水产销差率控制分析

供水管网产销差率是反映供水企业管理水平和运行效益的重要指标.介绍了供水产销差率的定义和分类,结合厦门水务集团近几年供水产销差率现状,分析了控制产销差率措施的效果.     

丙酮酸乙酯合成新工艺

以叔丁基过氧化氢(TBHP)为氧化剂,四丁基溴化铵(TBAB)为相转移催化剂,有效地将乳酸乙酯氧化合成丙酮酸乙酯,产品纯度达98% 以上.该反应操作简单,无污染, 为丙酮酸乙酯合成开辟了新方向.     

离子液体催化C_5馏分中二烯烃的聚合反应

合成了多种基于1-丁基-3-甲基咪唑阳离子的离子液体,并作为裂解C5馏分中混合二烯烃聚合反应的介质。考察了离子液体种类、反应温度、反应时间和添加Lew is酸对混合二烯烃聚合反应的影响。实验结果表明,以硝酸根为阴离子的离子液体对混合二烯烃的聚合反应具有一定的阻聚作用;以六氟磷酸根为阴离子的离子液体能明显促进混合二烯烃的聚合反应,提高二聚物的含量;添加Lew is酸(质量分数为1%的ZnCl2)的离子液体对混合二烯烃的聚合反应具有更明显的促进作用,其效果仅次于酸性氯铝酸类离子液体,反应温度以30℃以下为宜,温度过高将促使二聚物进一步聚合,形成三聚物乃至多聚物,降低二聚物的含量。     

PDC钻头在胜利油田深井钻井中的应用

胜利油田为提高深井钻井速度，试验应用了PDC钻头，结果表明，深井钻井应用PDC钻头可大幅度提高机械钻速，缩短建井周期，降低钻井成本，经济效益明显。通过大量的现场试验，扩大了PDC钻头在胜利油田的使用范围，并取得很好的效果，初步形成了PDC钻头推广应用区域模式。详细介绍了胜利油田不适用PDC钻头钻进的地层岩性，给出了钻头选型及钻井参数选择原则，并对应用效果进行了分析。     

小水电CDM项目在西部的开发现状及其优势

介绍国内小水电CDM项目开发现状，分析我国西部丰富的小水电资源分布及开发小水电CDM项目存在的潜力及优势，并提出在开发小水电CDM项目过程中应注意的有关问题。图2幅，表1个。     

油田企业优化备件管理的设想

针对油田企业装备设施系统备件管理的庞杂性，提出了4种优化备件管理的设想。在备件分类管理、库存管理模式及备件供应环节和管理流程上，结合计算机辅助技术，形成优化管理模式。提出的优化思路可以运用于石油石化企业的备件管理中，改进业务流程，促进物流管理一体化。     

The PBD-Closure of Constant-Composition Codes

We show an interesting pairwise balanced design (PBD)-closure result for the set of lengths of constant-composition codes whose distance and size meet certain conditions. A consequence of this PBD-closure result is that the size of optimal constant-composition codes can be determined for infinite families of parameter sets from just a single example of an optimal code. As an application, the sizes of several infinite families of optimal constant-composition codes are derived. In particular, the problem of determining the size of optimal constant-composition codes having distance four and weight three is solved for all lengths sufficiently large. This problem was previously unresolved for odd lengths, except for lengths seven and eleven.     

Spray deposition process study of SnO2silicon solar cells using orthogonal experimental design

With the “orthogonal experimental design” (OED), the dependence of conductivity and transparency of tin oxide films and open circuit voltage V_oc of SIS solar cells on the spray deposition process factors was studied. The OED technique was found to be a powerful method for realizing the best factor combination. Using OED, curves were obtained which clearly depict the effects of each factor on the SIS characteristics. The results of the experiments also illustrate exactly which variation in fabrication technique most affects the sheet resistance, V_oc, and film transparency. Under the optimal combination of conditions, a thin film doped with NH₄F was obtained, with about 90% transmission and a sheet resistance of about 80 Ω/□, along with an SIS structure with a V_oc of about 0.61 V.     

大角度倾转法在碳化物研究中的应用

蠕变过程中碳化物形貌，类型，数量和分布状态的变化直接影响着材料的高温性能，因而在材料的蠕变得到了广泛的重视，介绍了一种在碳膜萃取复型样品上利用Ｈ－８００透射电子显微镜的双倾样品台进行了大角度倾转，来观察碳化物形貌并鉴定其类型的试验方法。