Strategic Resource Development Options in England and Wales

This paper describes the options which had to be considered for new water resources in the development of the † National Rivers Authority's water resource strategy for England and Wales. The options included interregional transfers, strategic reservoirs, and a range of unconventional schemes including aquifer recharge, effluent re-use, groundwater abstraction where levels are rising, desalination, and transfer by sea. The main options are described and comparative costs are presented.     

The Microbiology of Lubricants and Oils for Water Supply Applications

Recent work in the US has shown that contact between lubricants and oils and drinking water can promote the growth of heterotrophic micro-organisms. It is unlikely that these species are pathogenic, and therefore harmful to man. However, the hygienic status of water distribution systems could be affected, leading to higher heterotrophic plate counts during routine sampling. Experimental work has been undertaken to study the microbiological impact of a range of lubricants and oils on drinking water. The methods have been based on an existing procedure for the assessment of the growth potential of drinking water, i.e. the 'assimilable organic carbon'test. The results of this work could serve as the basis of a future standard method for the rapid and inexpensive screening of oils and lubricants for their microbiological suitability in potable-water applications.     

Water and Wastewater Minimization: the Aire and Calder Project

The reduction of the waste of raw materials at source using clean technologies, recycling, and good housekeeping has considerable benefits for both the environment and industry. A demonstration project on wastewater minimization was completed in 1995 in the Aire and Calder catchments of West Yorkshire. The findings indicated cost savings for eleven firms of over $3 million/annum and further opportunities which, when implemented, could realize another $1 million/annum. The reduction in the amount of wastewater discharged either to sewer or river was 27%, with a potential to increase to over 40%. The payback period for 63% of the waste minimization opportunities is less than one year and many involve only a small initial investment. Waste minimization when widely adopted has prospects for cutting industry's costs, reducing demand for water and reducing the volume of effluent produced.     

A Large-Scale Grid-Based Hydrological Model of the Severn and Thames Catchments

This paper addresses the issues of scale and appropriate model complexity for large-scale hydrological models. A grid-based hydrological model, which employs the UK Meteorological Office Rainfall and Evaporation Calculation System, is applied to the Severn and Thames catchments using a grid scale of 40 km, and is shown to reproduce the observed mean annual runoff over a 10-year period to within 6% with no prior calibration. The variation in the model performance is strongly correlated with the linearity of the annual rainfall/runoff relationship and a climate index. At the monthly scale, runoff routing becomes significant, and the introduction of a two-parameter routeing algorithm significantly improves the monthly runoff simulations giving efficiencies of 90% and 88% for the Severn and Thames respectively. The results provide guidance to climate modellers looking for efficient and robust land-surface parameterizations, and indicate the potential application of such a modelling scheme to water resource managers.     

The Bacterial Quality of an Upland Stream

Faecal coliform concentrations were determined at stream and water inflow sampling sites within an upland catchment in North Derbyshire containing rough, semiimproved and improved pastures. The results indicated that, during its passage through the catchment, the faecal indicators of the stream increased, and this may constitute a health risk to cavers using a popular recreational cave into which the stream drains. The decline in streamwater quality suggests that a semipermanent store of bacteria existed in catchment soils, and hydrological processes operated to transfer bacteria from the land to the stream channel. Contrary to expectations, intra-catchment differences in the bacterial quality of water at inflow and stream sampling sites could not be related to the intensity of agricultural land use in adjacent areas. This is explained with reference to changes in the nature of hydrological transport pathways associated with the improvement of pastures.     

概周期过程周期初态的虚拟寻优法

概周期过程最优控制的核心是周期初态的寻优。本文提出一种虚拟寻优法,再配之以周期之间适当的状态连接,既大大减少了计算量和存贮量,又收到了较好的优化效果。水厂最优控制的仿真验证了本文方法的有效性。     

新型混凝土减缩剂评价研究

分别用胶砂和混凝土对混凝土减缩剂降低其干缩和自收缩效果进行了检测和评价．实验表明,混凝土减缩剂可显著减少胶砂和混凝土的干缩、自收缩,降低幅度达30％～50％．将混凝土减缩剂涂刷在胶砂试件表面,可以明显提高试件的保水性,降低其干缩．     

低温地板辐射采暖施工与运行中常见问题分析

通过调查发现低温地板辐射采暖在施工和运行阶段存在一些问题,这些问题的存在将对地板辐射采暖的使用效果、设备和管材的寿命以及建筑物的安全等带来影响。本文分别从材料选购、施工工艺和运行管理等方面分析了影响机理,并提出了注意事项,对施工和运行有参考价值。     

供热系统循环水泵变频调节的最佳工况

计算了热水供热系统循环水泵变频调节与阀门节流调节相比节省的电功率,变频调节的节能潜力与水泵体积流量成复杂函数关系,而不是与水泵体积流量的3次方成正比。水泵变频调节在实际工况体积流量与设计工况体积流量之比为0．577时节能潜力最大,为0．385。     

水泵变频调速方案计算机辅助论证

分析了变速泵和定速泵并联运行的特性,介绍了水泵变频调速方案计算机辅助论证软件的计算方法,结合工程算例,比较了几种水泵组合方案的技术经济性。