煤矿矿井水检测质量控制措施探讨

探讨了影响煤矿矿井水检测质量的主要因素,按照全过程、全要素控制的理念提出了检测前、检测中和检测后的控制措施。     

Comparison of Two Drying Schedules for European Hophornbeam (Ostrya carpinifolia Scop.) Lumber

Two types of conventional kiln-drying schedules (mild and harsh) based on moisture content (MC) were compared with regard to time, drying quality, and energy cost. The results were evaluated according to the classification of the European Drying Group. Proper drying periods of mild and harsh schedules were found to be 550 and 514 h, respectively. Evaluations in terms of drying quality indicated that better results were achieved with the mild schedule, especially when comparing drying defects and final MC. From an energy efficiency point of view, the harsh schedule, by saving 36 h of drying time, reduced electricity by 594 KWh and was therefore found to be $65 more profitable in this trial.     

Application of a Three-dimensional Wind Driven Circulation Model to Assess the Locations of New Drinking Water Intakes in Lake Ontario

A 3D transport model is used to perform a comparative analysis of several potential drinking water intakes located along the northwest shore of Lake Ontario between Toronto and Oshawa. The model is specifically used to assess each intake under both long- and short-term transport of a potential pollutant release from the Pickering Nuclear Generating Station and potential and actual pollutant releases from local land sources respectively. A model based on a 500 m grid resolution is calibrated using data collected in the aftermath of the 1992 tritium spill at the Pickering Nuclear Generation Station and subsequently used to simulate long-term transport. A model based on a 100 m grid resolution is verified using drogue studies and used to simulate short-term transport events. Both models are used to assess pollutant levels at each of nine potential intake locations under different wind scenarios and pollutant releases. Field data for the study included water quality and flow measurements from local sewers and rivers, and estimates of pollutant levels from the local waste water treatment plants. This paper describes the model setup for both the long-term and short-term transport models, calibration using field data, long-term transport modeling, short-term transport modeling, and the comprehensive analysis approach used to evaluate the nine potential intake locations proposed. Results indicated that four intakes in particular outperformed other intake locations by maintaining bottom pollutant levels within governmental standards and warning times that exceeded 20 hours.     

肝单光子发射计算机断层若干物理因素的讨论

我们于1985年对我院1984年开展肝单光子发射计算机断层以来的52例肝病人进行了分析总结。结果表明,肝单光子发射断层在诊断肝内占位性病变方面比普通肝静态γ照相有许多优点。需要指出的是,肝单光予发射断层的若干优点及诊断的准确性是与物理条件的正确选择和应用密切相关的。本文根据至今积累的近100例断层经验,从技术方面介绍了影响单     

云南省水环境状况及问题分析

根据2000年云南省主要河流水质监测评价结果，全省评价河段总长9280km中，水质为Ⅰ－Ⅲ类的河长占76．3％，总体上，云南省内各大水系水质良好，但水污染总体上正在加重，从1985－2000年，Ⅰ类河长年均减少2．3％，V类河长年均增长0．6％，废污水直接排入江河是引起污染的重要原因。水环境问题已成为社会经济可持续发展的关键问题，要切实加强水资源的保护，科学地开发利用水土资源，为了有效地改善水环境的质量，污染控制应从源头开始并采取综合治理措施。     

Energy Saving in Industrial Wood Drying Addressed by a Multiscale Computational Model: Board, Stack, and Kiln

This article proposes a multiscale computational model able to calculate energy consumption in a batch lumber kiln. A dual-scale computational model of wood drying deals with the boards/stack interaction and serves as a basis for the present work. A new module was added here that calculates heat losses through kiln walls (convection, condensation) and the energy used by each kiln component (fans, heating elements, humidifier, vacuum pump, etc.). The corresponding mathematical formulation is presented and then theoretical results are compared to those collected in an industrial vacuum kiln. As application example, the effect of air reversal, air velocity, and kiln insulation are exhibited, which depicts the great potential and prospects of this new tool for energy savings in relation to the product quality.     

Trade-offs for conflicting social objectives in the extraction of finite energy resources

Three social objectives figure prominently in the extraction of finite energy resources, namely income maximization, environmental quality, and inter-generational concern. Owing to lack of complementarity, the pursuit of these objectives often results in conflicts. As a result, extraction strategies should be based on the determination of trade-offs between the objectives. The paper deals with the formulation and illustration of a systems model to determine these trade-offs. The recognition of such trade-offs results in a greater conservation of the finite energy resource, and hence could act as an incentive for the development of alternative energy sources.     

Paste Residence Time in a Spouted Bed Dryer. III: Effect of Paste Properties and Quality Interactions

The aim of this study was to evaluate the effects of paste properties on residence time during drying in a spouted bed dryer with inert bodies. The effect of paste solids content, surface tension, and viscosity on the residence time distribution and the mean residence times were studied using factorial experimental designs. The inert bodies used were glass and polyethylene beads. The mean residence times varied from 13.6 to 16.3 and 12.2 to 17.7 min for drying on glass and polyethylene beads, respectively. The analysis of variance showed that mean residence times significantly depended on solids content and surface tension for glass beads and also on viscosity for polyethylene beads. The residence time distributions for all conditions studied fitted well to the perfect mixing cell when applying the continuous stirred vessels in series model analysis. The powder density, flowability, and particle size depended on paste properties and inert type.     

简易高性能纳秒脉冲发生器

为了实现电子散射飞行时间谱仪电子束的脉冲化及产生时一幅变换器的启动或停止信号。我们利用开关晶体管的雪崩特性研制了一个性能好，成本低的纳秒脉冲发生器。该发生器输出上升时间好于Ｉｎｓ，幅度达１０Ｖ的负尖脉冲，用作时一幅变换器的启动或停止信号；也输出上升时间约３ｎｓ，幅度５－３０Ｖ连续可调和宽度５－２３０ｎｓ可调的正脉冲，用作电子束脉冲化的调制信号，脉冲重复率为１５０×１０＾３ｓ＾－１。它可广泛用于类似     

Use of ultrafiltration for preparing improved tomato pulp

The characteristics of high-quality tomato pulp (commercial def.: crushed or diced tomatoes with about 30% tomato juice as packing medium) canned with tomato juice pulp enriched by ultrafiltration as packing medium were compared with those covered with conventional vacuum-concentrated juice.
Both hot- and cold-break products were prepared and those containing 20% serum-reduced packing juice proved to be the best, showing no signs of syneresis on storage and with improvements in sensory properties, colour and non-enzymatic browning; some volatile components were reduced.