Numerical analysis of flow-thermal coupling in micro-plasma welding pool of thin-wall part

The formed characteristics of thin-wall part is studied when it is in the process of MPAW. Finite element method is used to sinmlate the temperature field coupling flow field in the welding of thin-wall part. It is found that because of the obvious effect of heat accumution in cross-section, where the distribution of temperature field area presents trapezoidal inverted approximately in the molten pool and the non-molten pool area presents level. The surface tension, the electromagnetic force and buoyancy are considered for analyzing the effects on the fluid flow of welding-pool. It can be obtained that the surface tension is the main driving force in the welding pool, which is far greater than electromagnetic force and buoyancy.

Disinfection of swimming pools with chlorine and derivatives: formation of organochlorinated and organobrominated compounds and exposure of pool personnel and swimmers

Chlorination of pool water leads to the forma-tion of many by-products, chloroform usually being the most abundant. The paper reports the results of a study evaluating exposure of bath-ers and pool employees to trihalomethanes (chloroform, bromodichloromethane, dibromo-chloromethane, bromoform) in four indoor swimming pools with chlorinated water. Chlo-roform concentrations in environmental air samples when the pool was in use (about 9 h), in the range 1-182 μg/m3, were greater near the pool than in the change rooms, passageways and offices. Chloroform concentrations in per-sonal air samples of pool employees were in the range 18-138 μg/m3. Urinary concentrations of chloroform averaged (geometric means) 0.123 and 0.165 μg/l and 0.404 and 0.342 μg/l prior and at the end of exposure during in water and out of water activities, respectively. The significant increase in urinary excretion of chloroform confirms that the source of the contaminant was pool water. Absorption of chloroform, estimated from airborne and water concentrations, was significantly correlated with delta chloroform (after/before exposure) and urinary concentra-tions of chloroform at the end of exposure. As chloroform is a toxic and possibly carcinogenic substance, these observations pose a problem principally for the general population of pool users.

Bacteriological Quality of Swimming Pools Water in Port Harcourt Metropolis

The bacteriological quality of swimming pool water in Port Harcourt Metropolis was investigated. Ten (10) swimming pools were examined for microbial quality. Out of the 10 swimming pools, 4 (2, 4, 7 and 9) had bacterial isolates of 40 (100%). Swimming pools 2, 4, 7 and 9 had the bacterial isolates of 10 (25%), 8 (20%), 10 (25%) and 12 (30%), respectively. Of the forty (40) bacterial isolates identified, which represented 100 percent, 22 (55%) were identified as Staphylococcus epidermidis, 10 (25%) Bacillus cereus, 6 (16%) Micrococcus and 2 (5%) Staphylococcus aureus. Among the four swimming pools, 2 and 9 did not have the isolates of Staphylococcus aureus and Micrococcus, respectively. Based on the World Health Organisation (WHO) standard for recreational waters, the absence of coliform and fecal coliform bacteria (E. coli) revealed that the ten (10) swimming pools used for this study are considered to be within the acceptable limits for certifying microbiological water quality. However, there is a need for care and continuous maintenance of the swimming pools.

Influence of Swimming Pool Design on Hydraulic Behavior: A Numerical and Experimental Study

A swimming pool can be considered as a chemical reactor with specific hydraulic and macro-mixing characteristics. The nature of flow into the pool depends on various characteristics, such as water inlets and outlets (number and position), pool geometry, and flow rate. This study investigates how swimming pool design affects hydraulic behavior based on experimental and computational fluid dynamics studies (CFD). This paper does not describe the hydraulic behavior of all existing swimming pools, however the cases studied here are representative of pool designs widely used in Europe and the United States. The model developed, based on the principle of a stirred reactor, could be used as a first approach in describing the hydraulic behavior of regular pools. This model is suitable for the study of physical and chemical phenomena with long characteristic times. Other, more advanced, models were shown to be more suitable to the case of fast chemical processes.

Cancer risk assessment from exposure to trihalomethanes in tap water and swimming pool water

We investigated the concentration of trihalomethanes （THMs） in tap water and swimming pool water in the area of the Nakhon Path- om Municipality during the period April 2005-March 2006. The concentrations of total THMs, chloroform, bromodichloromethane, dibromochloromethane and bromoform in tap water were 12.70-41.74, 6.72-29.19, 1.12-11.75, 0.63-3.55 and 0.08-3.40 μg/L, respectively, whereas those in swimming pool water were 26.15-65.09, 9.50-36.97, 8.90-18.01, 5.19-22.78 and ND-6.56 μg/L, respectively. It implied that the concentration of THMs in swimming pool water was higher than those in tap water, particularly, brominated-THMs. Both tap water and swimming pool water contained concentrations of total THMs below the standards of the World Health Organization （WHO）, European Union （EU） and the United States Environmental Protection Agency （USEPA） phase Ⅰ, but 1 out of 60 tap water samples and 60 out of 72 swimming pool water samples contained those over the Standard of the USEPA phase Ⅱ. From the two cases of cancer risk assessment including Case Ⅰ Non-Swimmer and Case Ⅱ Swimmer, assessment of cancer risk of nonswimmers from exposure to THMs at the highest and the average concentrations was 4.43×10^-5 and 2.19×10^-5, respectively, which can be classified as acceptable risk according to the Standard of USEPA. Assessment of cancer risk of swimmers from exposure to THMs at the highest and the average concentrations was 1.47×10^-3 and 7.99×10^-4, respectively, which can be classified as unacceptable risk and needs to be improved. Risk of THMs exposure from swimming was 93.9%-94.2% of the total risk. Cancer risk of THMs concluded from various routes in descending order was： skin exposure while swimming, gastro-intestinal exposure from tap water intake, and skin exposure to tap water and gastro-intestinal exposure while swimming. Cancer risk from skin exposure while swimming was 94.18% of the total cancer risk.

Lesson 1: How Do I Get to the Swimming Pool

New Words找zhao v．speak to,look for别bie adv．don’t担心danxin v．worry游泳池youyongchi n．swimming pool怎么zenme pron．how走zou v．walk,get(to)向xiang prep．to,towards东dong n．east路口lukou n．crossing,junction,intersection右you n．right拐guai v．turn,change direction等deng v．wait(for) David is on the phone to Wang Jiaming．They are going for a swim．大卫:喂,我是大卫。我找王家明。

小熔池激光沉积制造薄壁件沉积宽度的模型预测及试验研究

将激光沉积制造的热物理过程与薄壁件的几何特性相结合,基于层间沉积过程中的能量守恒关系建立了可以适配于小熔池激光沉积制造薄壁件沉积宽度的预测模型。该模型详细阐述了沉积宽度与激光功率、扫描速度与送粉速率之间的关系。利用Ti–6Al–4V(TC4)粉末沉积制备了多组样品来进行预测模型的验证,结果表明,该模型可以准确地预测不同工艺参数下薄壁件的沉积宽度,提高了试验参数匹配的准确性与效率,并为小熔池激光沉积制造工艺成形精度控制奠定了理论基础。

Body fluid analog chlorination:Application to the determination of disinfection byproduct formation kinetics in swimming pool water

Disinfection by-products(DBPs)are formed in swimming pools by the reactions of bather inputs with the disinfectant.Although a wide range of molecules has been identified within DBPs,only few kinetic rates have been reported.This study investigates the kinetics of chlorine consumption,chloroform formation and dichloroacetonitrile formation caused by human releases.Since the flux and main components of human inputs have been determined and formalized through Body Fluid Analogs(BFAs),it is possible to model the DBPs formation kinetics by studying a limited number of precursor molecules.For each parameter the individual contributions of BFA components have been quantified and kinetic rates have been determined,based on reaction mechanisms proposed in the literature.With a molar consumption of 4 mol Cl2/mol,urea is confirmed as the major chlorine consumer in the BFA because of its high concentration in human releases.The higher reactivity of ammonia is however highlighted.Citric acid is responsible for most of the chloroform produced during BFA chlorination.Chloroform formation is relatively slow with a limiting rate constant determined at 5.50×10^-3 L/mol/sec.L-histidine is the only precursor for dichloroacetonitrile in the BFA.This DBP is rapidly formed and its degradation by hydrolysis and by reaction with hypochlorite shortens its lifetime in the basin.Reaction rates of dichloroacetonitrile formation by L-histidine chlorination have been established based on the latest chlorination mechanisms proposed.Moreover,this study shows that the reactivity toward chlorine differs whether L-histidine is isolated or mixed with BFA components.

Occurrence and formation of disinfection by-products in the swimming pool environment： A critical review

Disinfection of water for human use is essential to protect against microbial disease;however, disinfection also leads to formation of disinfection by-products（DBPs）, some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions（sweat, urine and saliva） and pharmaceuticals and personal care products（sunscreens, cosmetics, hair products and lotions） are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the disinfectant.Swimming pool air is also of concern as volatile DBPs partition into the air above the pool.The presence of bromine leads to the formation of a wide range of bromo-and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based disinfectant.This review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.

Swimming pool heating technology:A state-of-the-art review

A large amount of heat is needed to maintain the thermal comfort of both indoor and outdoor swimming pools in cold seasons.This motivates the development of various heating technologies aiming to reduce energy use,as well as operating and investment costs.Although their development can be traced back to the 1960s,a comprehensive review of these technologies is lacking.Therefore,this paper presents a comprehensive review of the development of heating technologies for swimming pools.This review firstly introduces available heat transfer models that can be used to calculate or predict heat loss and heat gain for swimming pools.Then,different passive and active technologies are summarized.The active heating technologies used for indoor swimming pools include solar collector,heat pump,waste heat recovery,geothermal energy,and congregation technologies.The active heating technologies used for outdoor swimming pools include solar collector,heat pump,PCM storage,geothermal energy,biomass heater,and waste heat recovery technologies.A discussion is presented on the practical and possible heating techniques for swimming pool applications.Finally,through the reviewed literature,future research opportunities are identified,to guide researchers to investigate swimming pool heating systems with suitable and relevant technologies.

Concentrations of disinfection by-products in swimming pool following modifications of the water treatment process:An exploratory study

The formation and concentration of disinfection by-products（DBPs） in pool water and the ambient air vary according to the type of water treatment process used. This exploratory study was aimed at investigating the short-term impact of modifications of the water treatment process on traditional DBP levels（e.g., trihalomethanes（THMs）, chloramines） and emerging DBPs（e.g., Halonitromethanes, Haloketones, NDMA） in swimming pool water and/or air. A sampling program was carried to understand the impact of the following changes made successively to the standard water treatment process： activation of ultraviolet（UV）photoreactor, halt of air stripping with continuation of air extraction from the buffer tank,halt of air stripping and suppression of air extraction from the buffer tank, suppression of the polyaluminium silicate sulfate（PASS） coagulant. UV caused a high increase of Halonitromethanes（8.4 fold）, Haloketones（2.1 fold）, and THMs in the water（1.7 fold） and, of THMs in the air（1.6 fold） and contributed to reducing the level of chloramines in the air（1.6fold） and NDMA in the water（2.1 fold）. The results highlight the positive impact of air stripping in reducing volatile contaminants. The PASS did not change the presence of DBPs, except for the THMs, which decrease slightly with the use of this coagulant. This study shows that modifications affecting the water treatment process can rapidly produce important and variable impacts on DBP levels in water and air and suggests that implementation of any water treatment process to reduce DBP levels should take into account the specific context of each swimming pool.

游泳池式轻水反应堆池壁池底及关键构件老化评估

核反应堆老化问题是决定反应堆安全运行的重要因素之一。中国原子能科学研究院游泳池式轻水反应堆(简称49-2堆)是一座典型的延寿运行的研究堆,也是中国目前运行时间最长的反应堆,开展老化研究对评估其继续延寿运行具有重要意义。本文主要以游泳池式轻水反应堆池底池壁(L03铝材)作为研究对象,对某些点缺陷的腐蚀情况进行分析,结果表明,49-2堆一次水水质条件引起铝合金的化学腐蚀较小,通过水下摄像机的检查,发现点缺陷无扩大和其他性质的变化,同时对池底地脚螺栓的检测,发现螺栓腐蚀程度轻微,X射线探伤表明内部无结构损伤情况,可侧面判定反应堆池壁池底的腐蚀情况较为良好,不会产生破口失水事故的发生。该结果对许可证延续申请具有重要参考价值。

49-2泳池堆低温供热全厂断电ATWS事故分析

针对49-2泳池式反应堆(简称49-2泳池堆)用于城市低温供热的工况,选取典型的全厂断电叠加紧急停堆系统失效(全厂断电ATWS)的超设计基准事故,使用RELAP5/MOD3.2程序对其热工水力参数瞬态特性进行分析。结果显示,49-2泳池堆具有很好的负温度反馈效应,事故后,由于燃料和冷却剂温度升高,从而引入一定的负反应性,使反应堆处于次临界状态;同时堆芯通过与堆水池建立自然循环,将衰变热带出,最终依靠自然循环方式将堆芯余热排出至上部大气环境热阱,验证了49-2泳池堆用于城市低温供热的固有安全性。

晋阳湖游泳场水HBsAg的污染及对水产养殖场水体的影响

本文对晋阳湖游泳场ＨＢｓＡｇ污染及其对水产养殖场水体的影响进行了调查。结果：游泳场水合计ＨＢｓＡｇ阳性率为４０％，且下层水ＨＢｓＡｇ阳性率明显高于中层水。整个湖水水体污染情况接近，湖水ＨＢｓＡｇ阳性率为５０％，淤泥为１００％，且淤泥中的ＨＢｓＡｇ约为水中的一万倍。结论为游泳场水ＨＢｓＡｇ的污染波及到整个湖水，间接证明淤泥是病毒聚积的场所，它的再悬浮对水体的污染有重大影响。

某钢筋混凝土水池角隅受力优化设计

为对钢筋混凝土水池进行优化设计,从现有水池设计方法的不足之处入手,结合某接触消毒池实际工程案例,通过有限元分析的方法,运用有限元软件midasGEN和ABAQUS研究了水池角隅受力情况,得出了池壁的应力分布情况,并给出了优化设计的方法和建议。结果表明:在布置加强筋时,高度和长度只需要达到池壁高度的1/5,就可以满足设计要求,同时在不显著增加钢筋应力的前提下减小了钢筋应力分布范围。可见传统配筋方式不够经济,对其进行优化是合理的。

基于单片机的游泳池水位控制系统设计

传统的游泳池水位控制采用人工的方式,依靠工作人员的经验进行水位的控制。该方式工作效率低、工作强度大。因此,有必要选择水位自动控制以节能、节约人力资源。该设计给出以AT89C51单片机为核心的游泳池水位控制系统设计的控制系统,将3个金属棒放置在需要测量的游泳池中,通过水的导电性实时测量当前水位变化,将检测信号实时与单片机交互,进而实现水位的控制。仿真环节通过Proteus搭建电路,合理设置实验对系统进行验证。实验表明文章设计的系统可靠、有效地检测并控制了目标水位。系统焊接了实物,实物也能够实现既定的功能。

二乙酰一肟-氨基硫脲法测定游泳池水中尿素实验条件的研究

本文拟建立二乙酰一肟-氨基硫脲测定游泳池中尿素的方法,从波长的选择、酸度的条件、试剂的加入量、温度的条件、加热时间来寻求最佳条件。结果表明:实验最理想条件是在酸性条件,线性方程结果良好,r=0.999 6,检测波长为480 nm,混合酸溶液加入量为5.00 m L,二乙酰一肟-氨基硫脲溶液加入量为2 m L,加热时间为20 min,线性范围为0~10 mg/L。该方法检测结果良好,可用于游泳池中的尿素测定。

室外泳池景观营造——以阿那亚柠檬泳池项目为例

室外泳池的设计是对园林景观多样性的补充,优质的室外泳池设计,是人工营造的亲水空间,也是增加园林景观互动性的要素之一。阿那亚柠檬泳池是本着“原生、融入”的设计理念,让柠檬泳池自身的设计特点,即从形式上,色彩上,植物配置上相互映衬,这即是本设计的最大亮点,又能让柠檬泳池犹若明珠一样镶嵌在周边环境中,与周边景观环境和谐统一,关键是做到了对当前景观的二次提升,为业主提供更深层次的娱乐休闲项目,从而达到改造的初衷。项目组通过对柠檬泳池完整统一设计,让景观更立体、设计更直观的展现在业主面前,其设计成果可以为今后类似项目提供借鉴。