红山水电站采用爆破膜装置取代调压塔

红山水电站装有４台１６００ｋＷ机组，属长压力引水管，多岔管和机组型号不一的电站，甩负荷时水击波在多岔管中的反射与传递情况比较复杂，曾考虑过调压塔及水阻器方案，因投资大，施工困难或动作不灵达不到预期效果而放弃。采用爆破膜装置，投资少结构简单，运行维护方便，且已有运行经验，红山水电站最终采用爆破膜装置。     

Treatment of coking wastewater by a UBF‐BAF combined process

BACKGROUND: Coking wastewater is a major pollutant, produced in large quantities in many countries worldwide. This study investigates the performance of a combined system for treating coking wastewater. The system is based on an upflow blanket filter (UBF) with a biological aerated filter (BAF). Efficiency is assessed according to organic pollutants and nitrogen removal. RESULTS: It was found that hydraulic retention time (HRT) had a greater influence on the removal efficiency of NH₃‐N than chemical oxygen demand (COD). The BAF facilitated simultaneous carbonaceous removal and nitrification, depending on the reactor height. The system removed 81.5% of COD and 96.4% of NH₃‐N when the total HRT was 46.7 h (15.4 h for UBF and 31.3 h for BAF). Gas chromatography/mass spectrometry analysis indicated that the main components of the coking wastewater were phenols and nitrogenous heterocyclic compounds. Certain refractory compounds decomposed in the anaerobic section, resulting in the production of intermediates. Although most organics present in the influent were absent from the final effluent, a few residual contaminants could not be fully eliminated by the system. CONCLUSION: The experimental results show that the present system is feasible for the treatment of coking wastewater. Copyright © 2007 Society of Chemical Industry     

Modeling of Electrochemistry and Heat/Mass Transfer in a Tubular Solid Oxide Steam Electrolyzer for Hydrogen Production

A finite‐volume based mathematical model has been developed for modeling hydrogen production by a tubular cell of solid oxide steam electrolyzer (SOSE), taking into account the electrochemical reactions and heat/mass transfer effects. The model is composed of three systems of nonlinear equations that govern the electric current density, energy balance in the solid SOSE cell, and energy balance in the flow of steam and hydrogen. The simulated hydrogen production rate proportional to the applied potential agreed well with the experimental measurements published in the literature. The intermediate modeling results indicated that the activation effect dominate the overall cell overpotential due to low exchange current density through the SOSE cell electrodes. Thus, higher electrode activity was identified as an important factor for enhancing cell performance. Parametric modeling analyses were conducted to gain better understanding of the SOSE characteristics. It was found that low‐temperature gas intake would cause a high temperature gradient in the tubular cell material at the inlet, possibly leading to a thermal expansion problem. The risk could be reduced by increasing the gas inlet temperature. It was also found that energy‐efficient SOSE hydrogen production can be achieved by reducing the hydrogen content in the steam intake and regulating the steam intake flow rate to an optimum that minimizes the overall electrical and thermal requirements. More parametric modeling results are discussed in this paper. The tubular SOSE cell model developed in this study can easily be expanded to accomplish tubular SOSE stack analysis for comprehensive system design optimization.     

A Sampling Theorem Approach to Traffic Sensor Optimization

With the objective of minimizing the total cost, which includes both sensor and congestion costs, the authors adopted a novel sampling theorem approach to address the problem of sensor spacing optimization. This paper presents the analysis and modeling of the power spectral density of traffic information as a 2-D stochastic signal using highly detailed field data. The field data were captured by the next-generation simulation (NGSIM) program in 2005. To the best knowledge of the authors, field data with such a level of detail were previously unavailable. The resulting model enables the derivation of a characterization curve that relates sensor error to sensor spacing. The characterization curve, concurring in general with observations of a previous work, provides much more detail to facilitate sensor deployment. Based on the characterization curve and a formulation relating sensor error to congestion cost, the optimal sensor spacing that minimizes the total cost can be determined.     

解读组织文化视野下的英语课堂教学

课堂也是一个组织,存在组织文化.主要从组织文化角度分析了英语课堂教学.英语课堂教学是课堂组织文化的载体,课堂组织文化可以分为操作(教学过程),理念(教学理念),假设(潜在的人生观,世界观),价值观三个层次.这三个层次互相影响,并影响着教学主体.揭示了组织文化三层次在英语课堂上的所在,阐释三层次的关系,以及其对英语教学和学习的影响,并对英语课堂组织文化管理提出建议.     

Toxic response of aquatic organisms to guide application of artemisinin sustained-release granule algaecide

In our previous study, we prepared the granules by embedding artemisinin into alginate-chitosan using microcapsule technology. Thesgranules can release artemisinin sustainably and have a strong inhibitory effect on the growth of both single Microcystis aeruginosa and mixealgae. To safely and effectively use artemisinin sustained-release granules to control algal blooms, the ecotoxicity was studied by assessing theacute and chronic toxicity to Daphnia magna(D. magna) and Danio rerio(D. rerio), along with their antioxidant activities. The results showethat the 48-h median effective concentration(EC50) of pure artemisinin to D. magna was 24.54 mg/L and the 96-h median lethal concentratio(LC50) of pure artemisinin to D. rerio was 68.08 mg/L. Both values were classified as intermediate toxicity according to the Organization foEconomic Co-operation and Development(OECD). The optimal algae inhibitory concentration of artemisinin sustained-release granules(1 g/Lhad low acute toxicity to both D. magna and D. rerio. The sustained-release granules had higher chronic toxicity to D. magna than to D. reriPartial indices of D. magna were inhibited by granules when the concentrations were larger than 0.1 g/L. Low granule concentration had ainductive effect on antioxidant enzyme activities in D. magna and D. rerio. With the increase of the exposure concentration and time, the enzymactivity presented a trend of first increasing and then decreasing, and the overall changes were significant. The change trend and range of enzymactivity indicated that the granules could cause serious oxidative stress to D. magna and D. rerio, and the changes were consistent with the resultof toxicity experimentation.     

陶粒砼联肢剪力墙结构中的连梁在反复荷载下的性能

本文对陶粒砼剪力墙结构中的连梁采用足尺试件(传统配筋连梁14根,对角斜配筋连梁5根),在低周反复荷载作用下,实测了连梁的受力性能,研究了强屈比、计算剪箍比、名义剪压比和跨高比等因素对连梁破坏形态、滞回延性和耗能性能的影响,并提出连梁强度计算公式。     

我国旱情旱灾情势变化及分布特征

在对1949—2008年县区以上的旱情旱灾数据和资料进行统计和分析的基础上,对我国近60年来旱情旱灾情现状及变化情势从特大干旱、农村饮水、农业干旱、城市缺水、生态环境和旱灾损失等不同的角度,对干旱灾害发生频率、影响程度、发生范围等几个方面进行了讨论。得出了干旱灾害在发生频次、严重程度和发生范围方面都呈现增加的态势,干旱不仅对农业,而且对工业生产以及江河、湖泊、湿地等生态环境造成严重影响,干旱灾害的影响已经波及经济社会发展的诸多领域,未来发生特大干旱的概率增加的结论。     

天花板水电站满管溜管的运用

在碾压混凝土坝的浇筑施工中,碾压混凝土入仓关系到大坝碾压混凝土的施工效率和施工质量。天花板电站成功运用满管溜管混凝土入仓,达到了随着坝体升高碾压混凝土快速施工的目的。     

防汛会商决策服务研究及应用

针对现行防汛会商决策支持系统数据分散、软件通用与复用性差等问题,研究基于平台、组件、知识图、可视化的综合集成决策服务系统。在SOA,J2EE服务体系和规范的平台技术架构的基础上,利用网格、中间件等技术,构建防汛会商综合集成平台。采用Web Service技术实现各类水文模型与方法的组件化并发布;通过知识图快速关联、组织防汛会商信息,描述防汛应用主题及业务关系,实现防汛会商信息的综合集成及统一管理,为会商者提供全面的数据、信息和决策服务。通过在陕西省防汛会商中的应用,突显了本决策服务系统的通用和灵活性等优点,最大限度地提高了决策服务效率。