Assessment of chemical and microbiological parameters of indoor swimming pool atmosphere using multiple comparisons

The aim of this study was to evaluate the air quality of an indoor swimming pool, analyzing diurnal and seasonal variations in microbiological counts and chemical parameters. The results indicated that yeast and bacteria counts, as well as carbon dioxide (CO₂), nitrogen oxides (NO_x) and O₃ concentrations, showed significant diurnal difference. On the other hand, temperature, relative humidity (R.H.), yeast counts and concentrations of CO₂, particles, O₃, toluene, and benzene showed seasonal differences. In addition, the relationship between indoor and outdoor air and the degree of correlation between the different parameters have been calculated, suggesting that CO₂, fine particles and NO_x would have indoor origin due to the human activity and secondary reactions favored by the chemical and environmental conditions of the swimming pool; while O₃, benzene and toluene, would come from outside, mainly. The overall results indicated that indoor air quality (IAQ) in the swimming pool building was deficient by the high levels of CO₂ and microorganisms, low temperatures, and high R.H., because frequently the limits established by the legislation were exceeded. This fact could be due to the poor ventilation and the inadequate operation of heating, ventilation, and air‐conditioning systems.     

Hydrodynamic drag constrains head enlargement for mouthbrooding in cichlids

Presumably as an adaptation for mouthbrooding, many cichlid fish species have evolved a prominent sexual dimorphism in the adult head. Since the head of fishes serves as a bow during locomotion, an evolutionary increase in head volume to brood more eggs can trade-off with the hydrodynamic efficiency of swimming. Here, the differences between males and females in three-dimensional shape and size of the external head surfaces and the effect thereof on drag force during locomotion was analysed for the Nile tilapia (Oreochromis niloticus), a maternal mouthbrooder. To do so, three-dimensional body surface reconstructions from laser scans and computational fluid dynamics simulations were performed. After scaling the scanned specimens to post-cranial body volume, in order to theoretically equalize propulsive power, the external volume of the head of females was 27% larger than that of males (head length + 14%; head width + 9%). These differences resulted in an approximate 15% increase in drag force. Yet, hydrodynamics imposed important constraints on the adaptation for mouthbrooding as a much more drastic drop in swimming efficiency seems avoided by mainly enlarging the head along the swimming direction.     

空气源热泵热水机组在游泳池水加热中的应用

以某文体活动中心为例,从耗热量计算、空气源热泵的选型、空气源热泵的能耗计算三方面阐述了空气源热泵技术在游泳池水加热中的应用,并将其与燃油锅炉的能耗费用进行了比较,以说明空气源热泵技术的优越性。     

小型游泳池池水消毒——臭氧消毒

本文通过臭氧消毒系统的工程实例,对其进行介绍、分析和总结,以供参考。     

ETFE薄膜在游泳馆中应用的防结露分析

通过分析围护结构不同部位发生结露的主要原因,有针对性地给出了防结露的解决方案,保证了游泳馆的正常使用。为双层薄膜围护结构系统的防结露设计提供了理论参考。     

Simulated Cryptosporidium removal under swimming pool filtration conditions

There has been no information available on the removal of Cryptosporidium oocysts or oocyst‐sized particles under the sand filtration conditions normally used for swimming pool water treatment. A pilot sand filtration plant has therefore been constructed at The University of Wales Swansea and operated under swimming pool conditions (25 m/h downflow, 30°C, 1.5 mg/L free chlorine, pH 7.3 to 7.5, alkalinity 120–150 mg/L as calcium carbonate). Removal of fluorescent polystyrene particles of a size range (1–7 μm) similar to the size of Cryptosporidium oocysts (about 5 μm) without added coagulant was less than 50%. Removal of the particles under the operating conditions above but with the addition of either of the coagulants polyaluminium chloride (PAC) or aluminium sulphate was capable of giving better than 99% removal of the particles.     

浅谈游泳池设计

本文就游泳池设计中水源预处理、水循环处理、恒温手段等三个方面进行比较, 讲述了现在游泳池设计中的主要作法以及各自的优缺点。     

一种应用于自行武器系统的固态功率控制器

为满足新一代自行武器供配电系统可靠性、维修性、机动作战下持续供电的需求,提出一种应用于自行武器系统的固态功率控制器(solid-state power controller,SSPC).以自行武器供配系统为背景,通过对配电技术现状及常规SSPC设计的分析,提出一直流二路输出固态功率控制器,从硬件和软件2方面进行设计研究.研究结果表明:应用软件实现原理和方法能够得到SSPC状态信号,为上位机实现针对负载的自动化管理和设计提供参考.     

基于跟踪微分器的自行高炮分数阶控制

针对自行高炮位置伺服系统跟踪速度要求高、射击时干扰强、跟踪精度对信号噪声敏感的特点,提出了一种基于跟踪微分器的分数阶控制律的改进方案。通过合理的假设和近似,建立了自行高炮位置伺服系统的饱和非线性模型;在此基础上设计了主令和反馈通道上的跟踪微分器,以滤除信号噪声得到工程实用的微分信号;再经由分数阶 PID 控制器得到控制量,以增加系统带宽。比较分析了设计的控制律与传统整数阶 PID 控制器在伺服跟踪和冲击力矩干扰下的控制效果。仿真结果表明,采用提出的方法能提高自行高炮响应速度和增加系统带宽,有效抑制噪声信号和外部力矩干扰。     

北京室内游乐馆结构设计

介绍了北京室内游乐馆的结构体系、结构规则性、荷载分项系数、材料等内容,并进行了多遇地震内力分析、性能化分析和设计以及基础分析,结果表明:该设计满足规范要求,达到了预期目标。