城市合流管道污水截流性能研究

本文通过大量实验研究,证明现况合流管道中截流井,由于没有考虑它特有的水流状态及各种损失,而按明渠均匀等速流计算、设计,造成污水截流效率较低,大量污水入河的现象。实验研究说明,影响槽式截流井截流效率的主要因素是槽深、槽长;影响堰式截流井的主要因素是堰高。并提出了有关小管径槽式、堰式截流井主要尺寸的计算经验式。     

溢流堰面水流的数值模拟

针对传统堰面设计方法中的不足,利用数值模拟方法,对三种不同典型堰剖面的过堰水流进行模拟,分析了不同剖面形状对堰面动水压强的影响,可为溢流堰剖面曲线的科学设计提供参考。     

某溢洪道堰闸段静力和抗震性能三维有限元分析

运用ANSYS软件对某溢洪道堰闸段静力及抗震性能进行了三维有限元分析,并采用振型分解反应谱法探讨了顺水流向和横水流向两种地震作用效应,为堰闸段的结构设计提供了依据。     

检查井内污水跌落充氧试验研究

检查井是污水管道内水流与外界空气接触的重要场所,管内氧含量对污水自净能力有明显影响。对西安市城区部分检查井内氧含量的调查发现,井内氧组分稀缺现象较普遍,而跌落水流可有效改善此现象。利用竖桶试验模拟研究检查井内跌水充氧的影响因素,结果表明:增大竖桶顶部孔径时,跌落水流的复氧效率和顶部小孔卷吸气量均增加,但随着孔径的增大此影响逐渐变小;随着跌水流量的增加,水垫层复氧效率与小孔卷吸气量缓慢增加;当水流跌落高度为0.6 m时,复氧效率约为0.4 m时的2倍;顶部小孔位置在跌落水流正上方且水平距离入口最远时,水垫层复氧效率最大,当小孔在桶盖边缘处时,水垫层复氧效率均低于小孔在水流正上方的复氧效率。     

应力状态下混凝土结构的盐雾侵蚀试验研究

预应力混凝土结构的盐雾侵蚀试验研究在国内外很少见。根据盐雾环境下应力状态混凝土试件的耐久性试验研究成果 ,阐述了在应力和盐雾共同作用下的结构破损规律 ,为制定预应力混凝土结构的耐久性设计规程提供建议。     

盐雾侵蚀条件下玄武岩纤维布加固混凝土构件的耐久性试验

国内外学者对纤维复合材料(FRP)加固混凝土梁的整体性能及其耐久性都做了大量的试验和理论研究,但是以往对FRP的研究大多集中在碳纤维复合材料(CFRP)及玻璃纤维复合材料(GFRP)等上面,而对性价比良好的玄武岩纤维(BFRP)加固混凝土结构的试验研究却很少。基于以上因素,通过对18个梁在不同的初始荷载水平情况下分别在自然环境和盐雾环境下的老化试验研究,结果表明:不同初始荷载水平对BFRP加固混凝土梁的影响较小;盐雾环境与自然环境下对比发现,BFRP加固混凝土梁具有较好的耐盐雾侵蚀能力。     

盐雾环境下氯离子在混凝土中扩散系数的研究

通过综合盐雾腐蚀箱模拟汕头地区大气盐雾环境,采用不同水灰比、不同比例粉煤灰掺合料、不同腐蚀时间的混凝土试件,提出了环境系数与粉煤灰影响系数,对Fick第二扩散定律进行了修正,并对修正后的扩散模型计算进行了简化处理.     

盐雾环境下混凝土中氯离子侵蚀加速试验的综述

盐雾环境下,氯离子侵蚀是混凝土结构耐久性退化的主要原因.在简述混凝土中氯离子侵蚀机理的基础上,分析了实际盐雾环境的形成、特征参数以及相应的影响因素.通过我国沿海地区的环境温湿度与盐雾加速试验设备控制参数进行的比较,发现现有盐雾箱加速试验规范参数变化范围小,不能有效模拟真实盐雾环境下混凝土中氯离子侵蚀规律,应对现有的盐雾箱试验设备进行改进,通过变化环境参数开展混凝土中盐雾侵蚀加速试验的相似性研究.     

广东省质量技术监督局9种产品监督抽查结果(二)

卫浴产品本次抽查了广州、佛山、中山、顺德等4个地区的卫浴产品60批次,经检验,合格51批次,产品抽样批次合格率为85.0%。不合格项目包括:盐雾试验、密封性能。据了解,盐雾试验不合格的配件在使用一段时间后,表     

将韧性作为设计的驱动力

金华白沙堤三十六堰灌区在2020年成功入选世界灌溉工程遗产名录,是浙江省现存最古老的堰坝引水灌溉工程,始建于27年.灌溉农田达1.86万hm2,从最上游沙贩堰到最下游中济堰,横跨45 km,水位落差 168 m.三十六堰的建设依循"阶梯–深潭"山区河流自然发育的地貌特征,在每个深潭的下游修筑堰坝,利用深潭对水流的消能作...     

新型电气火灾消烟剂的研制

针对电气火灾中产生的大量有毒烟雾，研制一种细水雾型消烟剂，能够通过润湿、凝并、粘结等物理作用以及化学反应沉降烟尘，去除有毒气体，达到快速消烟目的，平均消烟效率达85％以上。该消烟剂为绿色无污染产品，不会造成消烟范围内设备、装置的短路和腐蚀，火灾现场容易清洁。     

The Hydraulic Analysis of Side-Channel Spillways as Reservoir Outlets

This paper presents a simple computer-based methodology for analyzing the hydraulics of side-channel spillways, and concentrates on the performance of the spillway when the overflow weir is subject to heavy submergence - as may be the case when passing extreme floods as stipulated by the Reservoirs Act 1975. Published data, which define the relationship between the degree of submergence of a weir and the reduction in the weir's coefficient of discharge, is used to match the water profile in the receiving channel with that of the induced distribution of flow over the weir. Results are compared with those obtained from scale physical models.     

Hydraulic experiments on spillway weir profiles

Spillway weirs are the system for regulating the flow in open channel flow passages. Weirs are commonly used to alter the flow of rivers to prevent floods, measure discharge and also in nuclear reactors for uniform cooling purposes. This paper describes the hydraulic experiments conducted for finding the air entrainment on water under laminar flow conditions in open channel flow passage with various profiles of spillway at flow rates in the range of 100–650?lpm. The concept of the spillway system allows stabilisation of the free level of water and avoids variation in the free level of water along the flow passage as a function of flow rate. The main problem in the spillway is the profiling of weir crest. The criteria that need to be satisfied are: (i) there should be no flow separation from the crest and (ii) there should be a uniform circumferential flow to avoid flow asymmetry in the passage. Separation of flow leads to large impact velocity of the falling water, which would lead to large-scale entrainment of air. When flow adheres to the weir crest and upstream, the impact velocity of water with the free surface would be less and hence entrainment would also be less.     

细雾水灭火临界水滴粒径和用水量计算

本文分析了细雾水滴与浮升火焰羽流的相互作用,推导出雾滴在火场下降过程中的运动方程、热量衡算和汽化速率方程。通过龙格一库塔差分方法数值求解,得到不同火场条件下细雾水灭火的临界水滴粒径,临界灭火用水量。     

Interaction of water mists with a diffusion flame in a confined space

This paper describes the study of the interaction of water mists with a diffusion flame in a confined space with proper ventilation control. Water mist was generated by a single pressure nozzle and diffusion flames were produced from ethanol and pine samples, respectively. The LDV/APV system was employed to determine the water mist characteristics. The Cone Calorimeter was used to measure the heat release rate, oxygen and carbon monoxide concentrations and other important parameters of the interaction under various conditions. The test results showed that water mist suppressed the diffusion flame in the confined space through oxygen displacement, evaporative cooling and heat radiant attenuation, and enhanced the combustion through expansion of the mixture and chain reaction as well. Suppression played the dominating role when the water mists with enough volume flux were applied to the diffusion flame in confined space. The poorer was the ventilation, the easier the suppression. The water mists had a more complex effect on the solid sample than the liquid, and affected the smoke release rate and movement.     

浙中灌区景观中的风土建成遗产识别与 解析

将浙中地区风土建成遗产作为景观要素,基于民间 文献中的图文史料,运用“景观图谱法”分析2种灌区景观的 结构性特征。根据水利设施的不同,灌区景观可被分为陂塘景 观和堰坝景观,陂塘灌区的中心聚落多位于渠系上游,水利多 由单一宗族控制;而堰坝灌区水利由多宗族分享,且中心聚落 在渠系末端。通过深入调查其中宗族聚落发生的历史及水利社 会的变迁,揭示灌区景观体系的营建过程,解析水利社会的治 理机制。最后,归纳浙中灌区景观的总体特征,以期为日后建 成遗产的保护提供价值判断的依据。     

Aeration Performance of Triangular-Notch Weirs

Hydraulic structures have an impact on the concentration of dissolved oxygen in a river system, even though the water is in contact with the structure for only a short period of time. The same oxygen transfer that would normally occur over several kilometres in a river can occur at a single hydraulic structure, because the flow over a structure is typically highly turbulent, resulting in increased interfacial renewal. Plunging overfall jets from weirs are a good example of this fact, and the aeration properties of such structures have been studied widely in the laboratory and field over a number of years. This technical note (a) describes triangular-notch weirs having a different weir angle α and how they affect aeration performance, and (b) demonstrates that aeration efficiency decreases with increasing weir angle.     

The influence of drought-induced low freshwater flow on an upper-estuarine macroinvertebrate community

Severe drought in the Thames catchment during 1989 and 1990 resulted in increased water abstraction from the river Thames, reducing the amount of freshwater flowing into the Thames estuary over Teddington weir. Increased salinity levels were recorded in the upper estuary, related to the decrease in flow, which in turn affected the community of freshwater invertebrates inhabiting a site below Teddington weir. A large decrease in BMWP score was recorded following increased abstraction in both 1989 and 1990. However, the disappearance of taxa was not directly related to their perceived sensitivity to organic pollution, with Asellidae, Caenidae and Unionidae being amongst the first families to be affected. Multidimensional scaling ordination indicated that the community demonstrated a cyclical pattern of disturbance and recovery related to variations in salinity and flow-dependent influx of organisms via invertebrate drift. The study indicates that reducing freshwater flow below a critical level can have detrimental effects on the diversity of macroinvertebrate communities in certain sections of tidal rivers.     

钢板桩围堰在潮汐河流中的设计和施工

针对东莞市某输水工程位于潮汐河流的情况,采用了钢板桩围堰方案施工,文中对钢板围堰的设计、施工进行了分析,提出了围堰施工中应注意的事项,并比较了水中围堰与土中基坑设计的不同之处,为其他类似工程提供参考、借鉴。     

Predication of discharge coefficient of cylindrical weir-gate using adaptive neuro fuzzy inference systems (ANFIS)

Settlement of sediments behind weirs and accumulation of materials floating on water behind gates decreases the performance of these structures. Weir-gate is a combination of weir and gate structures which solves them Infirmities. Proposing a circular shape for crest of weirs to improve their performance, investigators have proposed cylindrical shape to improve the performance of weir-gate structure and call it cylindrical weir-gate. In this research, discharge coefficient of weir-gate was predicated using adaptive neuro fuzzy inference systems (ANFIS). To compare the performance of ANFIS with other types of soft computing techniques, multilayer perceptron neural network (MLP) was prepared as well. Results of MLP and ANFIS showed that both models have high ability for modeling and predicting discharge coefficient; however, ANFIS is a bit more accurate. The sensitivity analysis of MLP and ANFIS showed that Froude number of flow at upstream of weir and ratio of gate opening height to the diameter of weir are the most effective parameters on discharge coefficient.