Variation of biological and hydrological parameters and nitrogen removal optimization of modified Carrousel oxidation ditch process

To enhance the nitrogen removal, a systemic monitoring of the biological and hydrological parameters of Carrousel oxidation ditch in Chongqing Jingkou Wastewater Treatment Plant was carried out to study the feasibility of simultaneous nitrification and denitrification (SND). The variation and distribution of parameters such as flow velocity, concentration of dissolved oxygen (DO) and mixed liquor suspended solids (MLSS) in oxidation ditch were monitored and analyzed, which were major control factors for SND. The results showed that, the dimensional distribution of flow velocity, DO and MLSS were affected significantly by the operation condition of the aeration wheels. With all the four aeration wheels being in operation, DO and flow velocity were higher and the mixing of MLSS was sufficient. With three aeration wheels being in operation, the flow velocity in most of the bottom areas was enough to meet the basic requirements of no deposition, and the anaerobic region and aerobic region could exist simultaneously in one oxidation ditch, which was helpful to the process of SND. According to spatial distribution characteristics of the flow velocity, DO and soluble components under optimized condition, different functional zones of biochemical reaction in the Carrousel oxidation ditch system were defined, which might contribute to the optimization control and SND of Carrousel oxidation ditch.     

洛惠渠二支渠灌区末级渠系工程改造与管理

末级渠系改造是灌区节水改造的重要组成部分,加强改造工程管理是保障其发挥工程效益的关键。文中客观介绍洛惠渠灌区二支末级渠系工程现状和存在问题,探索其改造措施和加强管理途径,总结了工程改造效益。     

基于LS-DYNA的减震沟减震效应研究

为了研究减震沟的减震作用,运用大型动力分析软件LS-DYNA,基于具体工况分别对有减震沟和无减震沟的露天矿台阶爆破进行数值模拟.结果表明,减震沟距离爆源越近,减震效果越好,减震率最高可达77%,为减震沟的减震效应研究和类似工况提供了理论支持.     

Flow structure and channel change in a sinuous grass‐lined stream within an agricultural drainage ditch: Implications for ditch stability and aquatic habitat

Many drainage ditches in the Midwest have developed a geomorphological configuration characterized by vegetated bars, or benches, on the bottom of the ditch and a stream flowing within a channel inset into these bars or benches. Past work has focused on the sedimentology of the benches and the depositional processes involved in bench development. This study investigates the three‐dimensional flow structure and short‐term channel change in a small grass‐lined stream flanked by benches at the bottom of an agricultural drainage ditch in east central Illinois, USA. In particular, it focuses on the influence of channel curvature and bank vegetation on flow through the inset channel at two different stages and explores how the structure of the flow is related to documented patterns of channel change. Results indicate that the mean flow is characterized by a submerged high‐velocity core that mainly is confined to the centre of the channel by near‐bank zones of flow stagnation/separation induced by abrupt changes in channel alignment and by strong frictional effects of grasses extending into the flow along the channel margins. Where the high‐velocity core is close to the channel margins, minor erosional adjustments of the inset channel can occur in the form of bank erosion. Patterns of turbulence kinetic energy reflect the development of shear layers near the channel margins and surrounding the submerged high‐velocity core. Locations with strong turbulence also correspond to locations of minor bank erosion. The results indicate that the inset channel is a relatively stable feature, especially where the alignment of this channel is straight, but that erosion‐control treatments may be necessary locally where the inset channel impinges on the ditch bank. Although the development of benches, a geomorphic response to ditch maintenance, is commonly viewed as a threat to drainage efficacy, preserving or constructing benches and associated inset channels in drainage ditches can enhance aquatic habitat and water quality. Copyright © 2010 John Wiley & Sons, Ltd.     

利用HEC—RAS软件计算山洪沟水面线

本文以桦甸市某山洪沟为例,采用HEC—RAS软件,模拟分析了山洪沟在设计频率洪水下的水面线,为山洪沟治理工程的规模确定提供科学依据。计算结果表明,HEC—RAS软件在分析计算山区急流水面线时有较好的适用性,计算结果对工程有利,在山区河道及山洪沟治理工程中推荐使用该软件。     

基于简易吸水法的喷灌施肥冬小麦冠层截留量

喷灌施肥时的冠层截留会增加叶片灼伤风险,影响肥料利用效率。为了定量评估喷灌施肥时冬小麦冠层的肥液截留特性,以尿素为研究对象,采用简易吸水法测定了冬小麦拔节-灌浆期不同尿素溶液浓度的冠层截留肥液量和附着肥液当量厚度。结果表明:冬小麦拔节-灌浆期冠层截留肥液量随冬小麦生长显著增加,冠层截留肥液量与植株生态指标显著线性相关,相关程度依次为株高鲜重植株表面积叶面积指数;附着肥液当量厚度在拔节-灌浆期变化相对较小,变化范围为0.051～0.080 mm,均值为0.067 mm。在冬小麦抽穗期和拔节期,不同尿素溶液浓度的冠层截留肥液量和附着肥液当量厚度在p0.05水平上差异显著。研究提出的冬小麦生育期内冠层截留肥液量与株高的回归方程可用以估算冬小麦生育期内喷灌施肥时的冠层截留肥液量。     

拦截高速机动目标的非线性自抗扰制导律

为实现导弹对目标的高精度拦截, 本文提出了基于加权齐次函数的非线性自抗扰拦截制导设计方法. 首先, 提出了基于加权齐次函数的非线性扩张状态观测器在线估计视线角速率和由目标加速度等内外不确定性因素构成的总扰动. 其次, 设计了基于非线性扩张状态观测器的非线性自抗扰三维制导律对总扰动进行补偿, 该制导律克服了高阶非线性项与强耦合项等不利因素的影响, 提高了拦截制导精度. 本文通过分析误差系统的动力学行为证明了闭环制导系统的稳定性和收敛性. 本文提出的方法在拦截精度等方面优于已有的基于线性扩张状态观测器和基于fal函数的扩张状态观测器的自抗扰制导方法. 仿真结果验证了本文所提出方法的有效性和优越性.     

平原漏斗区高效生态含水层补给技术研究

针对中国黄泛平原井灌地区地下水超采引起的大面积地下水漏斗问题,选择山东省临清市项目区,利用土壤水动力学、水力学和地下水动力学等相关理论,实施了地下水回灌工程对技术方案和参数进行设计,计算其回灌效果。通过计算结果可知,该回灌工程在7 d的引水过程中,增加了52 310.82 m~3的地下水补给量,占地下水补给总量的60.7%。野外回灌系统流速监测和示踪试验表明,该工程设计方案可行。在原沟渠渗入补给的基础上,该种明沟—暗管—竖井回灌补源工程增加了地下水补给量,对地下水漏斗恢复和旱涝碱综合治理具有重要作用。     

福寿沟建设理念对于现代海绵城市建设的启示

近年来,传统灰色基础设施带来的"城市病"越发凸显。突发罕见的暴雨所导致的城市内涝给我国多地造成了重大的人员伤亡和财产损失。海绵城市建设是防治城市内涝的主要技术措施之一,其核心理念是将排水功能归还于自然。福寿沟是我国宋代时期建成的地下排水系统,是世界上早期最杰出的排水系统之一。福寿沟通过利用自然本身进行雨洪调蓄,其精妙的设计思想、工作原理对于现代海绵城市建设具有极强的指导意义。从国内外海绵城市的研究现状入手,充分挖掘海绵城市的深层含义,探究海绵城市构建的哲学思想,再引入福寿沟的建设理念,通过剖析福寿沟结构、工作原理、建设思想,结合《海绵城市建设技术指南》中海绵城市建设的五大基本原则,最终得出福寿沟建设理念对于现代海绵城市建设的三大启示,即规划引领,因地制宜,核心是"天人合一";生态优先,统筹建设,关键是"以人为本";根除病根,城镇转型,方法是"绿色先行"。     

动能拦截器逆轨拦截时攻击区的一种估算方法

为了解决逆轨拦截攻击方式下动能拦截器攻击区的估算问题,文章提出了一种攻击区的估算方法.首先给出了攻击区的一种简洁的表示方法,分析了初始横向速度偏差对攻击区的影响;接着对拦截器与目标之间不同初始相对距离对应的攻击区的特点进行了推导分析,得到了攻击区随初始相对距离的增加而演变的3种典型形态,给出了相应的估算方法;最后对所给出的估算方法进行了仿真验证.仿真结果说明所给出的估算方法是比较准确的.