Engineering design approaches for minimum fouling in submerged MBR

A contributor to success in managing membrane operations is to be able to identify suitable engineering design approaches to slow down the membrane fouling rate. Two such approaches were discussed in this study, namely: (1) offsite chemical and mechanical cleaning, and (2) air scouring. A longer subsequent operation time was observed after a membrane was cleaned chemically compared with mechanically. For air scouring during membrane operation, the investigation aimed at determining the crossflow velocity induced by coarse and fine bubble diffusers. Higher crossflow velocities were obtained with the latter. Uniformly distributed fine air bubbling might possibly have caused less uplift resistance and induced higher crossflow velocities. Such air scouring, at critical aeration intensity, was able to prolong the membrane operation for up to 8 months without needing chemical or mechanical cleaning.     

A case study of long-term RO plant operation without chemical pretreatment

Described herein is a case study of long-term reverse osmosis (RO) plant operation without applying chemical pretreatments to the feed water. This project was undertaken with the financial support from the Department of Bio-Technology, New Delhi, and the work was carried out by a research team from Central Salt and Marine Chemicals Research Institute (CSMCRI), Bhavnagar (Gujarat), India. A prototype plant with a 30,000 L/d capacity was designed, manufactured, installed and operated at the village of Mocha-Gorsar, located in the Porbandar district, to provide drinking water. The village was to be developed as a model Bio-Village where other projects related to village problems are also operated by other research institutes. Thin-film composite (TFC) membrane-based RO technology was indigenously developed by the institute for treatment of brackish water and waste water for the first time in India; it was used successfully in this plant, which gave a typical NaCl rejection of about 95%. This is a typical case study of RO plant installation where physical methods of pretreatment such as sand and micron cartridge filters were used; no chemical pretreatment of feed was employed for long-term brackish water desalination study. The idea was to avoid the usage of chemicals, which concentrate in the effluent water, might affect the environment and may not suit the village community. Plant performance during 24 months of continuous operation with respect to variable feed salinity, membrane cleaning and regenerations is discussed.     

Cleaning of viscous drops on a flat inclined surface using gravity-driven film flows

We investigate the fluid mechanics of cleaning viscous drops attached to a flat inclined surface using thin gravity-driven film flows. We focus on the case where the drop cannot be detached either partially or completely from the surface by the mechanical forces exerted by the cleaning fluid on the drop surface. Instead a convective mass transfer establishes across the drop–film interface and the fluid in the drop dissolves into the cleaning film flow, which then transports it away. The characteristic time scale of dissolution is much longer than the advection time scale in the film flow. Thus, the shape and size of the drop can be considered as quasi-steady. To assess the impact of the shape and size of the drop on the velocity of the cleaning fluid, we have developed a novel experimental technique based on particle image velocimetry. We show the velocity distribution at the film surface in the situations both where the film is flowing over a smooth surface, and where it is perturbed by a solid obstacle representing a very viscous drop. We find that at intermediate Reynolds numbers the acceleration of the starting film is overestimated by a plane model using the lubrication approximation. In the perturbed case, the streamwise velocity is strongly affected by the presence of the obstacle. The upstream propagation of the disturbance is limited, but the disturbance extends downstream for distances larger than 10 obstacle diameters. Laterally, we observe small disturbances in both the streamwise and lateral velocities, owing to stationary capillary waves. The flow also exhibits a complex three-dimensional converging pattern immediately below the obstacle.     

旋液流态化流体阻力与传热的试验研究

摘要对某公司换热器的运行情况。采用旋液流态化技术设计了模拟试验方案。首先在φ57mm×3．5mm×2000mmPVC管内进行旋液流态化清洗试验,然后在碳钢管上内置不同螺距的钢丝螺旋线进行流体阻力测试,并进行旋液流态化与空管的对比传热试验。结果表明：旋液流态化技术清洗管道中人工污垢只需时间145s,没有发生粒子沉积和堵塞的现象,安全可靠性好;旋液流态化流体阻力△p随着Re的增大而增大,摩擦系数随着Re的增大而减小,流体总阻力48．7kPa低于供水压力,总传热系数平均提高幅度13．3％,强化传热效果好。     

一种不确定RFID数据流清洗策略

原始RFID数据流含有大量噪声且具有不确定性,必须在使用之前对其进行数据清洗,而清洗策略是清洗质量的保证。提出一种适合不确定RFID数据流的清洗策略。该清洗策略引入了最大熵原理,对待清洗的RFID元组的特征属性进行权重选择,并根据清洗节点的时间消耗以及误差进行清洗成本分析,决策出最佳的清洗方法。仿真实验结果表明,该清洗策略提高了不确定RFID数据流的清洗效率与精度。     

不停车清洗预膜在2号高炉净循环水系统的应用

循环冷却水系统长期运行过程中，由于多种因素影响，管道、阀门、水泵等设备产生结垢和腐蚀，为使水系统保持长期正常运行，减缓腐蚀结垢速度，需投加杀菌剂和阻垢缓蚀剂，2a进行一次清洗和预膜。主要介绍了2号高炉净循环水系统不停车清洗预膜的步骤、效果，并推荐在工况相似循环水系统中参考应用。     

Olfactory coordinated area coverage

This paper proposes an olfaction based methodology to automatically cover an unknown area enabling the decoupled cooperation of a group of floor cleaning mobile robots. This method is based on the utilisation of low cost chemical sensors in cleaning mobile robots, in order to differentiate clean from dirty areas. The experimental results show that the use of olfactory capabilities allows to efficiently cover and clean a certain area, and demonstrate the possibility of coordinating several mobile robots without the need of expensive sensing capabilities, map building or complex algorithms for task scheduling.     

交互式数据清理系统的研究

当今数据清理方案需要反复进行数据质量分析以查找错误，为修复它们而进行的转换需要运行很长的时间。用户需要忍受长时间的等待，而且经常需要撰写复杂的转换脚本。我们所探讨的交互式数据清理系统，它能紧密地将转换和偏差检测集成在一起，只要发现偏差，用户就可以交互式地使用简单的图表操作、实例描述逐渐建立一个转换，无需书写复杂的程序或忍受很长的延时。     

基于ARM的小型湖面漂浮物清扫机器人设计

结合当前机器人技术和嵌入式技术的融合发展,采用嵌入式Linux操作系统、WIFI和ARM11等,提出、研究并设计出了小型湖面漂浮物清扫机器人系统,详细阐述和给出了总体方案设计、硬件设计、软件设计等系统设计过程.该系统经实践验证:机器人能够顺利的实现前进、后退、转向和作业操作;系统具有操作简单、安全平稳、经济环保、适应性强等特点.     

Cleaning for Improved Indoor Air Quality: an Initial Assessment of Effectiveness

Abstract A study was conducted to characterize the indoor environment of a multifloor, multiuse, nonproblem, noncompliant building through long-term monitoring for biological, chemical, and particulate pollutants. The study also assessed the effects of cleaning on indoor air quality by providing a program to monitor baseline levels, providing a rigorous (deep) cleaning of the building, and then continuing to monitor after implementation of a standardized, improved, cleaning program. To assess the effectiveness of the cleaning program, air, surface, and dust data from monitoring prior to the cleaning program were compared with those obtained while the improved housekeeping program was in place. Correlations between pollutants and other environmental factors were studied. The data suggest that the improved cleaning program contributed to indoor air quality through the reduction of airborne dust mass, total volatile organic compounds, and culturable bacteria and fungi.