A new image fusion performance metric based on visual information fidelity

Because subjective evaluation is not adequate for assessing work in an automatic system, using an objective image fusion performance metric is a common approach to evaluate the quality of different fusion schemes. In this paper, a multi-resolution image fusion metric using visual information fidelity (VIF) is presented to assess fusion performance objectively. This method has four stages: (1) Source and fused images are filtered and divided into blocks. (2) Visual information is evaluated with and without distortion information in each block. (3) The visual information fidelity for fusion (VIFF) of each sub-band is calculated. (4) The overall quality measure is determined by weighting the VIFF of each sub-band. In our experiment, the proposed fusion assessment method is compared with several existing fusion metrics using the subjective test dataset provided by Petrovic. We found that VIFF performs better in terms of both human perception matching and computational complexity.     

Sampled-data output feedback control of a class of uncertain nonlinear systems

In this paper, we study the problem of sampled-data output feedback control for a class of uncertain nonlinear systems. The main contributions of this work are two-fold: (i) we develop a systematic design procedure of sampled-data output feedback controller; and (ii) we provide a theoretical analysis of the sampled-data closed-loop system, which shows that the state of the plant can be regulated into any given neighborhood of the origin by an appropriate choice of design parameters and sampling period. Furthermore, the bound of the neighborhood is proportionally dependent on the sampling period. Finally, an illustrative example is given to demonstrate the effectiveness of the presented method.     

Application mobility in pervasive computing: A survey

Pervasive computing applications often need to maintain uninterrupted computing experiences when users move across devices. This advanced feature, recognized as application mobility, brings many challenges to the pervasive computing community. For a better understanding of the challenges and existing approaches to application mobility, this paper surveys related work with a classification and comparison framework established along four dimensions of design concerns in application migration: temporal, spatial, entity and other concerns. Through this survey this paper attempts to provide a systematic reference for developers to leverage off among different migration strategies for seamless application mobility. Moreover, it sheds some light on future work directions.     

Improved concentration and separation of particles in a 3D dielectrophoretic chip integrating focusing, aligning and trapping

This article presents a dielectrophoresis (DEP)-based microfluidic device with the three-dimensional (3D) microelectrode configuration for concentrating and separating particles in a continuous throughflow. The 3D electrode structure, where microelectrode array are patterned on both the top and bottom surfaces of the microchannel, is composed of three units: focusing, aligning and trapping. As particles flowing through the microfluidic channel, they are firstly focused and aligned by the funnel-shaped and parallel electrode array, respectively, before being captured at the trapping unit due to negative DEP force. For a mixture of two particle populations of different sizes or dielectric properties, with a careful selection of suspending medium and applied field, the population exhibits stronger negative DEP manipulated by the microelectrode array and, therefore, separated from the other population which is easily carried away toward the outlet due to hydrodynamic force. The functionality of the proposed microdevice was verified by concentrating different-sized polystyrene (PS) microparticles and yeast cells dynamically flowing in the microchannel. Moreover, separation based on size and dielectric properties was achieved by sorting PS microparticles, and isolating 5 μm PS particles from yeast cells, respectively. The performance of the proposed micro-concentrator and separator was also studied, including the threshold voltage at which particles begin to be trapped, variation of cell-trapping efficiency with respect to the applied voltage and flow rate, and the efficiency of separation experiments. The proposed microdevice has various advantages, including multi-functionality, improved manipulation efficiency and throughput, easy fabrication and operation, etc., which shows a great potential for biological, chemical and medical applications.     

A novel method to construct 3D electrodes at the sidewall of microfluidic channel

We report a simple, low-cost and novel method for constructing three-dimensional (3D) microelectrodes in microfluidic system by utilizing low melting point metal alloy. Three-dimensional electrodes have unique properties in application of cell lysis, electro-osmosis, electroporation and dielectrophoresis. The fabrication process involves conventional photolithography and sputtering techniques to fabricate planar electrodes, positioning bismuth (Bi) alloy microspheres at the sidewall of PDMS channel, plasma bonding and low temperature annealing to improve electrical connection between metal microspheres and planar electrodes. Compared to other fabrication methods for 3D electrodes, the presented one does not require rigorous experimental conditions, cumbersome processes and expensive equipments. Numerical analysis on electric field distribution with different electrode configurations was presented to verify the unique field distribution of arc-shaped electrodes. The application of 3D electrode configuration with high-conductive alloy microspheres was confirmed by particle manipulation based on dielectrophoresis. The proposed technique offers alternatives to construct 3D electrodes from 2D electrodes. More importantly, the simplicity of the fabrication process provides easy ways to fabricate electrodes fast with arc-shaped geometry at the sidewall of microchannel.     

On the security and improvement of a two-factor user authentication scheme in wireless sensor networks

User authentication is a basic security requirement during the deployment of the wireless sensor network (WSN), because it may operate in a rather hostile environment, such as a military battlefield. In 2010, Khan and Alghathbar (KA) found out that Das’s two-factor user authentication scheme for WSNs is vulnerable to the gateway node (GW-node) bypassing attack and the privileged-insider attack. They further presented an improved scheme to overcome the security flaws of Das’s scheme. However, in this paper, we show that KA’s scheme still suffers from the GW-node impersonation attack, the GW-node bypassing attack, and the privileged-insider attack. Hence, to fix the security flaws in KA’s scheme, we propose a new user authentication scheme for WSNs. The security of the user authentication session in the proposed scheme is reduced by the model of Bellare and Rogaway. The security of partial compromise of secrets in the proposed scheme is reduced and analyzed by our adversarial model. Based on the performance evaluation, the overall cost of the proposed scheme is less than that of KA’s scheme. Hence, we believe that the proposed scheme is more suitable for real security applications than KA’s scheme.     

深覆盖层河道闸坝电站防沙布置试验研究

某闸坝式水电站坝址覆盖层深厚,河道欠宽阔,发电引用流量比例较高,受调节库容限制,库区泥沙将很快输移到达坝前,引水防沙问题突出。本文对施工围堰作为其电站枢纽引水防沙体系的效果进行了水工模型试验研究和分析。对四种挡沙坎布置型式进行了对比试验研究。表明,利用原有挡水围堰,结合纵向挡沙坎与排沙底孔联合作用既有利于施工方便,拉沙效果又较好,可达到电站＂门前清＂,较好的解决了大流量闸坝式电站的引水与防沙之间的矛盾。本研究成果的成功实施可减少工程投资,缩短工期,尤其对于在低水头、大单宽的多沙河流上修建的闸坝工程具有较好的借鉴意义。     

基于PLC的沙集闸自动化远程监控系统设计

介绍了采用可编程逻辑控制器(PLC)技术的沙集闸自动化远程监控系统基本结构、设计方案、监控系统控制策略、监测内容、辅助功能、PLC的技术特点以及节制闸闸门升、降流程.     

生态流域建设理念与发展模式探讨

建设生态流域、协调流域生态环境保护与社会经济发展间的关系已成为当前流域研究的重点.对生态流域的概念及内涵进行了探讨,阐述了生态城市和生态乡村建设示范的规划目标,提出开展生态流域建设应重点开展流域分区与保护、城市群发展规划、生态产业规划、人工系统结构与功能调整四个方面的研究,以流域人工系统物质流和能量流的生态化为核心,深...     

环境评估在加强水电建设项目生态保护中的作用——以安谷水电站为例

随着水电开发强度增大,公众环保意识增强,水电建设项目环境管理要求不断提高,水电工程建设和运营中生态保护措施也得到不断加强,在此过程中,环境影响技术评估工作发挥了积极的推动作用。以安谷水电站为例,阐述了两次技术评估时安谷水电站所采取的主要生态保护措施及环保投资内容,通过对措施及水电站建设投资的对比,说明了水电建设项目环境影响技术评估严格把关的作用。