Relationship between types of surface shear stress profiles and membrane fouling

Shear stress has been recognized as an important parameter in controlling particle back-transport from membrane surfaces. However, little is known of the relationship between transient shear conditions induced by air sparging and fouling control near membrane surfaces. In this paper, the different types of surface shear stress profiles that had beneficial effects on minimizing reversible surface fouling were examined. The relationship between different statistical shear parameters (e.g. time-averaged shear, standard deviation of shear and amplitude of shear) and fouling control that have been used by others were examined as well. It was found that the fouling rate for membranes subjected to transient shear conditions was lower than for membranes subjected to constant shear conditions. The magnitude, duration and frequency of the shear conditions were found to have an impact on the fouling rate of membranes. It was also found that although some statistical shear parameters could generally be used to relate shear and fouling, they were inadequate to relate surface shear stress to fouling, for all transient shear conditions examined.     

An integrated model for the design of air-cooled chiller plants for commercial buildings

Cooling load calculation is the first step in designing the air-conditioning system of a building. The calculated cooling capacity with appropriate buffer is then used to select the number and size of chillers in the system. N + 1 is a common formula used by designers to size the chiller plants in Hong Kong buildings, where N is the actual number of chillers required and 1 is a redundant chiller provided to ensure reliability. This paper reviews the problem of excess capacity and discusses the risk exposure of chiller systems without redundant chillers. The cooling load profiles of the chiller plants of four medium-sized commercial buildings in Hong Kong are reviewed. The risk exposure of chiller systems without redundant chillers can be minimized by applying risk-based preventive maintenance. The just-in-demand design reduces capital cost of the building and frees up funds for continuous energy measurement and improving the energy efficiency of chiller plant systems. This paper presents a model for designing chiller plants that improves the energy efficiency of the plant in a cost effective and thoughtful manner. It is designed with consideration of the life cycle of the plant and real-time continuous commissioning, monitoring, measurement, comparison and execution for better energy management.     

Performance evaluation and design guidelines for stratum ventilation

This paper evaluates the performance of stratum ventilation systems for small to medium individual offices, open offices, classrooms, and retail shops operated under elevated room temperatures according to governmental guidelines. With proper design, stratum ventilation can maintain a thermally comfortable environment that has a horizontal airflow at head level, a small and reverse temperature gradient between the head and foot levels, and a high air distribution performance index.     

Capillary Network‐Like Organization of Endothelial Cells in PEGDA Scaffolds Encoded with Angiogenic Signals via Triple Helical Hybridization

Survival of tissue engineered constructs after implantation depends on proper vascularization. The differentiation of endothelial cells into mature microvasculature requires dynamic interactions between cells, scaffold, and growth factors, which are difficult to recapitulate in artificial systems. Previously, photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels displaying collagen mimetic peptides (CMPs), dubbed PEGDA‐CMP, that can be further conjugated with bioactive molecules via CMP‐CMP triple helix hybridization were reported. Here, it is shown that a bifunctional peptide featuring pro‐angiogenic domain mimicking vascular endothelial growth factor (VEGF) and a collagen mimetic domain that can fold into a triple helix conformation can hybridize with CMP side chains of the PEGDA‐CMP hydrogel, which results in presentation of insoluble VEGF‐like signals to endothelial cells. Presentation of VEGF‐like signals on the surface of micropatterned scaffolds in this way transforms cells from a quiescent state to elongated and aligned phenotype suggesting that this system could be used to engineer organized microvasculature. It is also shown that the pro‐angiogenic peptide, when applied topically in combination with modified dextran/PEGDA hydrogels, can enhance neovascularization of burn wounds in mice demonstrating the potential clinical use of CMP‐mediated matrix‐bound bioactive molecules for dermal injuries.     

A Colorimetric Hydrocarbon Sensor Employing a Swelling‐Induced Mechanochromic Polydiacetylene

Exceptional challenges have confronted the rational design of colorimetric sensors for saturated aliphatic hydrocarbons (SAHCs). The main reasons for this difficulty are the extremely nonpolar nature of these targets and their lack of functional groups that can interact with probes. By taking advantage of a mechanochromic conjugated polydiacetylene (PDA) and the hydrocarbon‐induced swelling properties of polydimethylsiloxane (PDMS), a sensor film that enables simple, colorimetric differentiation between a variety of C5 to C14 aliphatic hydrocarbons is fabricated. The unprecedented PDA–PDMS composite sensor undergoes a blue‐to‐red colorimetric transition on a timescale that is dependent on the chain length of the hydrocarbon target. In addition, the development of the red color is directly proportional to the swelling ratio of the film. This straightforward approach enables naked‐eye differentiation between n‐pentane and n‐heptane. The versatility of the sensor system is demonstrated by using it for the colorimetric determination of kerosene in adulterated diesel oil. Finally, the observation that a PDA microcrystal in the film undergoes significant expansion and tearing in concert with a blue‐to‐red colorimetric transition during the swelling process provides direct evidence for the mechanism for the mechanochromic behavior of the PDA.     

Personalized Healthcare System for Chronic Disease Care in Cloud Environment

The rapid increase in the number of patients with chronic diseases is an important public healthcare issue in many countries, which accelerates many studies on a healthcare system that can, whenever and wherever, extract and process patient data. A patient with a chronic disease conducts self‐management in an out‐of‐hospital environment, particularly in an at‐home environment, so it is important to provide integrated and personalized healthcare services for effective care. To help provide effective care for chronic disease patients, we propose a service flow and a new cloud‐based personalized healthcare system architecture supporting both at‐home and at‐hospital environments. The system considers the different characteristics of at‐hospital and at‐home environments, and it provides various chronic disease care services. A prototype implementation and a predicted cost model are provided to show the effectiveness of the system. The proposed personalized healthcare system can support cost‐effective disease care in an at‐hospital environment and personalized self‐management of chronic disease in an at‐home environment.     

HF RFID Reader Antenna with Loop Switch for Avoiding Magnetic Coupling

This paper studies the magnetic coupling between two adjacent loop antennas that are parallel to each other in a plane and presents a new practical method to avoid the resulting magnetic coupling interference. The study focuses on the high frequency radio‐frequency identification (RFID) system for casino applications, where several loop antennas are closely built into a game table to monitor gaming chips. In this case, neighboring loop antennas may severely interfere with each other by magnetic coupling, which leads to the malfunction of the RFID system. In this paper, we present a practical loop antenna with a new loop switch circuit for avoiding magnetic coupling. The loop switch circuit is integrated with a matching circuit and automatically operated by using an interrogating signal from a reader. We verified the validity of the proposed design by showing that an RFID reader with the proposed antenna can exactly and separately read the gaming chips placed on the different betting zones of a game table.     

Optimization of Photovoltaic Reflector System for Indoor Energy Harvesting

This study proposes a solution for optimizing the distance between a solar module and reflector for an indoor energy harvesting system. It is a process in which energy(ambient light) is captured and converted directly into electricity. Inside a building, this energy could be used to supply power to wide range of portable equipment or offset other electrical energy usage and associated costs. The proposed reflector element was designed and tested in a real indoor environment to confirm its effectiveness. A distance-optimization method for the placement of a polycrystalline photovoltaic (PV) module and a mirror was described, and the performance characteristics of the system were investigated qualitatively through visual observation and quantitatively through measuring voltage and ampere values. The solar PV system with a reflector element displayed a 10% increase in voltage when compared with that without. As the distance between PV module and the reflector increased, the voltage and ampere reading decreased, thus the distance was optimized to gain maximum readings. Various studies employing reflectors have also showed increases in voltage readings with different designs, suggesting that reflectors are economically viable optical elements that can boost the voltage output of a PV module. In practice, the distance-optimized PV module can be placed in buildings with extended indoor lighting duration away from disrupting building activity.     

一种基于颜色尺度不变和FANN搜索的图像匹配算法

针对彩色图像匹配大多数仅利用图像灰度特征,忽视彩色信息,在颜色相近区域易造成误匹配的问题,引入颜色不变量,提出一种用于彩色图像的颜色尺度不变匹配算法.该算法首先将图像的RGB 颜色模型转换到高斯颜色模型.随后,通过计算颜色不变量代替灰度信息作为输入,建立多尺度空间,并使用 SIFT 算法提取特征点,构建特征描述子.最后,选择其中一幅图的特征描述矢量为基准,利用FANN算法在另一幅图的特征描述矢量中,寻找基准图像特征矢量的最优解即匹配对,从而完成两幅图像的匹配.实验证明,相对于传统的SIFT图像匹配算法,本文的算法匹配正确率更高,图像匹配质量更好.     

广域复杂流体系统中基于无线传感网的数据保存关键技术研究进展

流体系统包括城市供水管网、天然气供给管网等,是具有经济和社会价值的重要基础设施。它们具有分布地域广、结构复杂、规模庞大、难以检测等特点,在出现泄漏、污染等异常时难以快速发现和准确定位。随着传感器技术、通信技术、微机电技术等的发展,利用无线传感网来对系统进行监测成为研究热点。由于在流体系统中通信困难,数据被监测到后很难实时传送给用户,只能暂时保存在传感器节点(简称节点)上,等待适当的时刻再进行上传。但是,节点具有体积微小、易损坏、存储容量小、通信能力弱、能量有限等特点,如何可靠地存储大量的数据是一个难点问题。目前,已有部分工作对这个问题进行了研究。为了解该领域研究的进展,文中对相关工作进行了细致地分析、对比、归纳和总结,介绍了它们的优缺点,并对未来的研究方向进行了探讨。