加气灌溉对部分土壤生境因子的影响

通过温室小区试验,研究了加气灌溉对土壤生境因子的影响。结果表明:与对照处理相比,加气灌溉降低了4.0%的平均土壤含水量,增加了1.5%的平均土壤O_2含量、3.4%的平均土壤温度、3.7%的平均土壤NO_3~-—N含量及1.0%的平均土壤NH_4~+—N含量。加气灌溉对试验中观测的土壤生境因子的影响不显著(p0.05),但土壤生境因子的微小改变可能会大幅改变土壤的环境效应和作物产量及品质,值得进一步研究。该研究对深入研究和客观评价加气灌溉技术具有重要意义。     

Sustainability of Natural and Mechanized Aerated Ponds for Domestic and Municipal Wastewater Treatment in Palestine

Abstract

More than half of the current wastewater treatment facilities constructed in Palestine are waste stabilization ponds (WSP) and have several problems in their operation. This article evaluates three selected case studies on the various pond systems including WSP, algae- and duckweed-based ponds (ABP and DBP, respectively) and one mechanically aerated lagoon (AL) system. The effects of various design and operating parameters on the pond system' performance, with special emphasis on nitrogen removal, are discussed. The effluent quality of WSP and AL complies only with BOD limits, but not with microbiological limits prescribed for agricultural purposes, as determined by national standards. ABP and DBP achieved nitrogen removal only under high surface area demand (5-7 m2capita-1). Suitable plans for modifying existing aerated lagoons or for upgrading natural lagoons are suggested in order to comply with microbiological standards for effluent use in restricted irrigation. Finally, the suggested sustainability criteria for the evaluated pond systems may help the decision makers, as well as their designers and donor countries, to better select and design low-cost treatment options for sustainable wastewater management in developing countries.     

谈粉煤灰加气混凝土砌块墙体裂缝的防治问题

一种轻质墙体材料,具有良好的隔热性能,施工较为简便这是粉煤灰加气混凝土砌块的优点,反之由于砌块强度等级低、吸水率高、收缩变形大,墙体裂缝引起渗漏、开裂现象经常发生。希望通过本文分析粉煤灰加气混凝土砌块墙体裂缝的产生原因及特征,针对其防治措施,以某住宅小区为例进行探讨,能有效根治墙体开裂的质量通病。     

宽尾墩与消力墩在班多水电站的应用

结合班多水电站整体水工模型试验,提出了利用宽尾墩能够收缩水流、抬高闸室内水面的特点,改善了泄洪闸堰面上出现的负压;针对下游河床冲刷偏深的问题,通过在混凝土护坦上设置消力墩,极大地减轻了下游冲刷.试验推荐的修改体型已经被工程采用.     

砼加气块墙体及抹灰裂缝控制

混凝土加气块作为粘土砖的替代产品已广泛的应用在施工中,而且应用中也产生了相应的负面影响,最具代表性的就是墙体开裂。本文结合实际的项目建设的工作,对控制砼加气块墙体表面裂缝进行了具体的分析。     

基于迁钢连退机组工程浅谈对炉压控制系统D7档板的更改方案

本文基于迁钢连退机组工程,针对目前应用的炉压控制系统的D7档板在其构成和控制方式方面进行了分析和介绍,针对其存在的缺点,提出了能够代替该系统且满足工艺要求的新方案。     

掺气水流相间作用力模型分析

本文分析了掺气水流内部结构形态及水、气两相间速度滑移的特征，得到如下结论：在掺气水流中，宏观的相间速度滑移不会很大；水、气两相间动量的传递以惯性推动作用为主，并给出了虚质量力的具体表达式。     

某办公楼填充墙裂缝的分析与处理

夏热冬冷地区,粉煤灰加气混凝土砌块在框架结构中运用普遍.文章对加气混凝土砌块墙体裂缝形成的原因进行了分析,并结合工程实例对裂缝进行处理,同时提出了防治裂缝的措施.     

Efficiency of operation of a T-250/300–240 turbine without moving blades of last stages of the low-pressure cylinder

The results of detailed computations performed for actual electric and heat loads, pressure in the condenser, and other operating parameters are used to consider the changes in the efficiency of operation of a T-250/300–240 turbine after the removal of moving blades of the last stages of the low-pressure cylinder. It is shown that the expediency of running the turbine with removed blades should be determined proceeding from the expected modes of operation of the cogeneration plant in question for the whole year. __________ Translated from élektricheskie Stantsii, No. 11, November 2005, pp. 47–52.     

掺气水舌运动微分方程及其数值解法

在重力、浮力和阻力作用下建立了掺气水舌运动微分方程，并应用四阶龙格-库塔(Runge-Kutta)法得到其数值解；最后将挑流水舌外缘挑距计算值与原观值作了对比，其最大相对误差为3．4％．