Solar stills for production of distilled water

Solar stills have been designed to produce water for use in teaching and research laboratories. Various designs and configurations have been constructed and tested over the past 10 years. The original double-surfaced cascade stills (stills A and B) were constructed in aluminium and were rather expensive. Later models termed Series D and E were of galvanised mild steel with stainless steel distillate drains and safety overflow drains. These galvanised steel units suffered from severe corrosion after a few years of operation. The latest design series F, is built in aluminium with stainless steel distillate drains and automatic feed valves. All of the stills produce very pure distilled water (conductance ～1.5 × 10^?6 Ω^?1 cm^?1; pH 6.8–7.4) at a cost which is below that of conventional electrically heated stills.     

英国国家电网公司在电力系统状态估计器及安全分析方面的经验

本文叙述了由安装在英国国家电网公司新国调中心的新型能量管理系统所提供的实时网络分析的应用，并介绍了第一年的运行经验．对经常出现的某些状态估计问题的解决方法和作者所作的尝试的结论进行了讨论，以对安全估计器的结果与现有的离线研究方法的结果进行比较．文章还对应用实时网络分析时遇到的一些原始缺陷的观察结果和在短时段及较长时段内解决这些问题的方法进行了讨论．     

Durban's Newest Water Resource - The Inanda Dam

The Inanda Dam is one of a series of reservoirs constructed to utilize the water resources of the Umgeni River, which rises in the Natal midlands and reaches the Indian Ocean at Durban, South Africa. The structure exploits the local topography and geology, with mass concrete founded on the granite forming the right bank and river bed, and a clay core earth embankment on the weaker left bank. Due to high ambient temperatures, the placing temperature of the concrete had to be controlled to avoid crack formation. Mix designs were modified by the addition of blast-furnace slag, and the mix water was cooled using liquid nitrogen to reduce the placing temperature of the concrete. Major floods also occurred, and although they caused little damage to the structure itself serious damage was sustained by the existing water-supply infrastructure, resulting in a review of the operational strategy of the system. The reservoir is to be operated initially as a river regulator with downstream abstraction. However, in order to provide additional security, a tunnel aqueduct linking the reservoir directly to the water-treatment works is under construction.     

ECOLOGICAL RISK-ASSESSMENT METHODOLOGY: A UK CASE STUDY FOR LANDFILLS

The paper presents an ecological risk-assessment methodology which (a) addresses surface-water exposures to aquatic mammals and birds, and (b) accounts for long-term accumulation and biomagnification of pollutants. The methodology has been adapted from those developed in the USA for compliance with US Environmental Protection Agency requirements, and combines predicted or measured surface-water concentration data with information on the natural history of wildlife species and chemical-specific bioaccumulation factors, to determine whether estimated exposures would exceed toxicological criteria. Whilst the methodology is applied to metals in leachate discharges from landfill sites, the general approach is applicable to other industrial sites. The approach could provide the basis for a shift towards more numerical risk-based ecological assessments in a wide variety of contexts.     

The Management of Water Colour in Peatland Catchments

The problems of water-colour management in peatland catchments are discussed. Colour may be managed in three areas of the reservoir catchment system: on the catchment itself, in the channel/conduit system and within the reservoir. Whilst a number of workers have considered the management of catchment areas and some have evolved tributary turnout strategies, no previous research has considered the role of the reservoir in the amelioration or enhancement of water colour. The management of water colour at Thornton Moor catchment (near Bradford) is described. In this catchment a staged approach has been adopted, with colour being managed in an integrated manner at three stages along the catchment/conduit/reservoir system.     

Water-Resource Allocation for Recreation, Leisure and Amenity

The paper (a) assesses the social and economic demands for water-related recreational, leisure and amenity facilities, (b) reviews the ways in which these demands are currently satisfied for lakes, reservoirs, rivers and canals, and (c) identifies possible future trends. The significant degree of interaction with other uses of water is also discussed.     

Optimization of Sampling Resources

T his paper reports on an investigation into the efficient routing of sample collection in the Lincoln Division of Anglian Water. Samples have to be collected from more than 600 sample points across three functions and at frequencies ranging from daily to once in two years. The organization of this activity is clearly complex.
As a result of the review carried out using manual methods, the additional 15 000 water samples which are required annually are now being collected with no increase in staff resources. The scale of the effort required for this review prevents it from being repeated except at infrequent intervals; yet without frequent reviews the efficiency of routes is eroded as the required pattern of samples changes. A computer system is therefore being developed, offering the prospect of halting the drift away from efficiency and the speedy evaluation of alternative strategies.     

Inter-Basin Water Transfers and Drought Management in the Kielder/Derwent System

During the dry years between 1989 and 1994, inter-basin water transfers from the Kielder system augmented flows in the River Derwent, and these flows substituted compensation releases from Derwent reservoir to retain storage for supply and recreational purposes.
The paper discusses the use of the Kielder transfers together with their impact upon (a) flow regime, (b) water quality, and (c) instream ecology of the River Derwent. Also, implications of the increasing use of water transfers in the UK are critically evaluated from the perspective of sustainability.