水动力条件对全程自养脱氮工艺启动研究

CANON工艺需要部分短程硝化提供亚硝酸盐,所以CANON工艺存在溶解氧难控制的问题,特别是在反应器较小的情况。本文采用设有挡板的改良SBR,通过机械搅拌形成剧烈水流搅动,精确控制溶解氧,研究了不同搅拌速率对CANON工艺启动的影响。结果表明,机械曝气能成功启动了CANON工艺,且获得平均总氮去除率达79.40%,剪切应力的提高有利于脱氮性能的提升,机械曝气启动方式相比于鼓风曝气更加容易控制。     

衡水电厂3B给水泵汽轮机转速摆动原因分析

给水泵小汽轮机的转速摆动是给水系统中常见的问题,引起的原因有测量不准、PID参数整定不当、伺服系统故障等多个方面。介绍了衡水电厂3B给水泵汽轮小机转速摆动故障的分析解决过程,分析了EH油质对电液伺服系统的重要性,提出了相关检修维护注意事项。     

Do lower electricity storage costs reduce greenhouse gas emissions?

In the electricity sector, innovation in large-scale storage is anticipated to reduce costs and improve performance. The effect on greenhouse gas emissions of lower storage costs depends on the interactions between storage and the entire grid. The literature has disagreed on the role of storage in reducing emissions. In this paper we present a stylized model, which suggests that the effect of storage costs on emissions depends on the supply responsiveness of both fossil and renewable generators. Under common conditions in the United States, lower storage costs are more likely to reduce emissions when wind investment responds to equilibrium electricity prices and when solar investment does not. Simulations of a computational model of grid investment and operation confirm these intuitions. Moreover, because of its effect on coal and natural gas–fired supply responsiveness, introducing a carbon dioxide emissions price may increase the likelihood that lower storage costs reduce emissions.     

限速值对信号交叉口交通安全的影响分析

为研究交叉口进口道车辆限速值对交叉口的安全和运行产生的影响,通过微观仿真平台,分析车辆在交叉口限速分别为30,38和46 km/h时的车均延误、车均行程时间,并将车辆行驶轨迹输入安全辅助评价(SSAM)软件中展开分析。结果表明,车辆限速值的提高对车均延误的影响不大,但会减小车辆在进口道的车均行程时间。另外,限速值从30 km/h提高到46 km/h,引起的碰撞时间(TTC)、后侵占时间(PET)数值变化不显著,但使总冲突数从42个增加到59个。     

Assessing and Mitigating the Effects of Windblown Soil on Rare and Common Vegetation

Acting under the auspices of the US Endangered Species Act, we quantified wind erosion and its effects on rare and common plant species on a semi-arid military installation in Hawaii. Our goal was to develop management strategies, based on local data, to aid the conservation of rare and common indigenous plants and their habitats. We collected windblown soil coming off of roads and other disturbed soils to assess likely impacts to plants occurring at certain heights and distances from disturbed surfaces. We then subjected plants in a glasshouse to windblown dust treatments, designed from our field data to simulate erosion events, and evaluated the effect of these treatments on photosynthesis and survival. We also designed several field experiments to examine the in-situ effects of windblown soil and soil substrate on germination, growth rate, and survival of indigenous and nonindigenous plants. We conclude from these experiments that most direct effects of windblown soil to plants can be effectively mitigated by locating roads and training areas at least 40 m from sensitive plant habitats and through vegetation management to maintain at least 11% aerial cover on disturbed surfaces. Effects of soil type on germination, growth, and survival was species-specific, emphasizing the importance of species trials prior to, or during, rehabilitation efforts.     

中国黄土高原地区的风蚀灾害及其防治

对我国黄土高原地区的风蚀情况及其严重危害作了简要阐述，指出坚持实施水土保持综合治理是防治风蚀灾害的根本途径，并对防治工作对策提出若干建议．     

自激振荡磨料射流的基本理论与初步试验

自激振荡磨料射流是在自激振荡脉冲射流和前混合磨料射流基础上,提出的新型射流。为此,重点讨论了自激振荡磨料射流喷嘴的结构和工作原理,分析了脉冲频率和幅值等参数对磨粒加速效果的影响。根据初步研究表明,磨粒速度受脉冲频率和幅度影响很大,磨粒速度可超过前混合磨料射流中磨粒的速度,最大钻孔速度比前混合磨料射流提高４１％ 。这一成果有望用于坚硬物料的切割和特种加工、石油钻井、大洋采矿、难采矿体的开采、坚硬岩石巷道（遂道）掘进、表面清洗等领域。     

循环磨料射流综合理论分析

循环磨料射流是磨料射流的一种重要形式。循环磨料浆液被高压水加速后直接输入喷嘴，构成具有强大打击力的磨料射流；特别适用于锻件、轧制件的除鳞除锈，铸件清砂等表面处理。要保证循环磨料射流在工业中应用，必须首先解决两个关键问题，即循环磨料射流浆体在管路中的正常流动、磨料的悬浮与沉降规律以及过碎的微小磨粒的剔除，以满足高效、连续的作业。本文论述了循环磨料射流的工作原理和主要工作参数的确定方法。     

Wind energy development in California,USA

Windfarms have been developed rapidly in California in the last few years. The impetus has been a legislated goal to generate 10% of California's electricity by windpower by the year 2000, and generous state and federal tax incentives. Windpower is promoted as environmentally benign, which it is in traditional uses. The California program, however, is not traditional: it calls for centralized development of a magnitude sufficient to offset significant amounts of fossil fuels now used to generate electricity.Centralized windfarm development, as exemplified by the Altamont Pass, Tehachapi Mountains, and San Gorgonio Pass developments, involves major road building projects in erosion-sensitive terrain, effective closure of public lands, and other detrimental effects. A windfarm consisting of 200 turbines with 17-m rotors located in steep terrain 16 km from an existing corridor might occupy 235 ha and physically disturb 86 ha. With average annual wind speeds of 22.5 km/h, the farm would generate about 10×10⁶ kWh/year at present levels of capacity. This annual production would offset 1% of one day's consumption of oil in California. To supply 10% of the state's electricity (at 1984 production rates) would require about 600,000 turbines of the type in common use today and would occupy more than 685,000 ha. It is likely that indirect effects would be felt in much larger areas and would include increased air and water pollution resulting from accelerated erosion, degradation of habitat of domestic and wild animals, damage to archaeological sites, and reduction of scenic quality of now-remote areas of the state.     

交通事故发生规律与城市道路系统的规划设计研究

笔者分析了城市交通事故发生率与道路等级、道路断面形式、路网密度、交叉口形式、道路车速的关系及交通事故人群的分布规律,认为道路宽而稀、支路缺乏、街道功能不清是我国城市道路网与用地微观布局的基本特点。大量数据分析表明,这种路网体系与我国的城市交通事故率偏高有着密切关系。路网规划是城市路网建设的基本依据,笔者认为,应当将降低城市交通事故率作为路网规划的考虑内容之一,同时指出,应在路网规划中合理选择道路断面形式、交叉口形式,建议适度加密路网、健全支路体系、理清街道功能,并考虑城市道路的车速控制与驾驶心态调整。