Treatment of linear alkylbenzene sulfonate (LAS) wastewater by internal electrolysis--biological contact oxidation process

Surfactant wastewater is usually difficult to treat due to its toxicity and poor biodegradability. A separate physico-chemical or biochemical treatment method achieves a satisfactory effect with difficulty. In this study, treatment of the wastewater collected from a daily chemical plant by the combination processes of Fe/C internal electrolysis and biological contact oxidation was investigated. For the internal electrolysis process, the optimal conditions were: pH = 4-5, Fe/C = (10-15):1, air-water ratio = (10-20):1 and hydraulic retention time (HRT)= 2 h. For the biological contact oxidation process, the optimal conditions were: HRT = 12 h, DO = 4.0-5.0 mg/L. Treated by the above combined processes, the effluent could meet the I-grade criteria specified in Integrated Wastewater Discharge Standard of China (GB 8978-1996). The results provide valuable information for full-scale linear alkylbenzene sulfonate wastewater treatment.     

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.     

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.     

交互式白板在教学中的应用

交互式白板实现了与计算机的交互控制,是一种集软硬件技术于一体的媒体技术。不同于其他媒体,其对教学的影响是多方面的,内容的呈现、互动环境的营造、课堂的生成、教学设计等等。随着交互式白板在教学中的应用,广大师生将对其进行更加深入的研究。     

基于无线通信技术的便携式血糖实时监测系统设计

本文采用植入式血糖传感器,结合智能手机和3G网络技术,对糖尿病人的血糖水平进行实时监测,并自动将数据通过手机网络传送到医院的监护中心保存。当血糖水平低于或高于设定的阀值,手机会发出声音报警,并向设定的号码发送短信息显示病人当前情况和所在位置或向医院监护中心报告。     

光学薄膜元器件外观特性机器视觉检测系统

本系统利用工业级摄像头及开发包的机器视觉功能与计算软件编程控制技术相结合,通过与输入控制系统中的标准膜片模板外观品质进行对比,实现高速高效、准确识别检测光学薄膜器件中滤光片的外观缺陷。可在生产线上根据外观品质标准模板中设定的类别进行自动分类装盒。     

一种嵌入式大量数据处理技术的研究

在检测、监控过程中常会遇到嵌入式系统采集和处理大量数据的问题,本文以复合光路膜厚监控仪为例,从系统结构组成、运算量的优化等方面对上述问题进行了探讨。