Optimization of Conditions for Preparation of Carbon Origin Solid Electrodes Modified with Carbon Nanotubes

A multi-walled carbon nanotubes (MWCNTs) were used for modification of two solid electrode types, glassy carbon electrode (GC), which is widely used for modification in electroanalysis, and, for the first time, paraffin impregnated graphite electrode (PIGE). The optimization of MWCNT/PIGE and MWCNT/GC electrodes was carried out by altering ultrasonication parameters (ultrasonication time, ultrasound generator performance, and dispersing agent). The preparation of modified electrodes was investigated. The most electrochemically sensitive MWCNT/GC electrode was prepared with nanotubes sonicated for 30 min and the most sensitive MWCNT/PIGE for 20 min, both using ethanol/water solution as dispersing agent and 500 W ultrasound generator performance. Both electrodes were successfully used for analysis of lead performed by DC voltammetry. Current responses were measured for the concentration of lead (II) in range from 1 × 10^?5 to 5 × 10^?5 mol dm^?3 for MWCNT/PIGE and also MWCNT/GC electrode.     

石蜡填充型丙烯酸酯吸油性树脂的合成及性能

以过氧化苯甲酰(BPO)为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,甲基丙烯酸丁酯为单体,聚乙烯醇为分散剂,石蜡为填充剂,采用悬浮聚合法合成了填充型吸油树脂。通过对产物的吸油率、保油率和脱油性能的测试研究了各反应物用量对树脂性能的影响,用正交实验法确定了最佳工艺。结果表明:石蜡、引发剂、交联剂和分散剂的质量分数分别为1.0%、0.4%、1.6%和1.0%(基于单体质量),反应温度80℃,反应时间5 h,水与单体质量比8∶1时,合成的树脂在48 h饱和吸油率为23.80 g/g。与未添加填充剂的吸油树脂比较,石蜡填充型丙烯酸酯吸油性树脂的吸油率、保油率提高,脱油性能更好,但凝胶分率变化不大。     

A secure and robust information hiding technique for covert communication

The unprecedented advancement of multimedia and growth of the internet has made it possible to reproduce and distribute digital media easier and faster. This has given birth to information security issues, especially when the information pertains to national security, e-banking transactions, etc. The disguised form of encrypted data makes an adversary suspicious and increases the chance of attack. Information hiding overcomes this inherent problem of cryptographic systems and is emerging as an effective means of securing sensitive data being transmitted over insecure channels. In this paper, a secure and robust information hiding technique referred to as Intermediate Significant Bit Plane Embedding (ISBPE) is presented. The data to be embedded is scrambled and embedding is carried out using the concept of Pseudorandom Address Vector (PAV) and Complementary Address Vector (CAV) to enhance the security of the embedded data. The proposed ISBPE technique is fully immune to Least Significant Bit (LSB) removal/replacement attack. Experimental investigations reveal that the proposed technique is more robust to various image processing attacks like JPEG compression, Additive White Gaussian Noise (AWGN), low pass filtering, etc. compared to conventional LSB techniques. The various advantages offered by ISBPE technique make it a good candidate for covert communication.     

乳液型清蜡剂的研究及效果评价

本文结合油井结蜡的特点和清蜡剂的研究进展,综合考虑清蜡剂使用的安全性和环保性,通过有机溶剂和表面活性剂复配的方法,制备出毒性低、不易燃、密度较大、清蜡速率高的乳液型清蜡剂。     

Centralized embedding hypersphere feature learning for person re-identification

ABSTRACT

Deep metric learning has become a general method for person re-identification (ReID) recently. Existing methods train ReID model with various loss functions to learn feature representation and identify pedestrian. However, the interaction between person features and classification vectors in the training process is rarely concerned. Distribution of pedestrian features will greatly affect convergence of the model and the pedestrian similarity computing in the test phase. In this paper, we formulate improved softmax function to learn pedestrian features and classification vectors. Our method applies pedestrian feature representation to be scattered across the coordinate space and embedding hypersphere to solve the classification problem. Then, we propose an end-to-end convolutional neural network (CNN) framework with improved softmax function to improve the performance of pedestrian features. Finally, experiments are performed on four challenging datasets. The results demonstrate that our work is competitive compared to the state-of-the-art.     

石蜡/膨胀石墨复合相变储热材料的研究

以膨胀石墨为基体,石蜡为相变储热介质,利用膨胀石墨对石蜡良好的吸附性能,制备出了石蜡／膨胀 石墨复合相变储热材料。由于毛细作用力和表面张力的作用,石蜡在固-液相变时,很难从膨胀石墨的微孔中渗 透出来。实验结果表明,石蜡/膨胀石墨复合相变储热材料没有改变膨胀石墨的结构和石蜡的固-液相变温度, 且其结合了石墨高的导热系数和石蜡大的相变潜热,因而储热密度较高,导热性能好。其相变潜热与对应质量 分率下的石蜡相当,储/放热时间比石蜡明显减少。     

石蜡/膨胀珍珠岩复合相变储能材料的研究

以膨胀珍珠岩为吸附材料,石蜡为相变储能材料,制备了石蜡/膨胀珍珠岩复合相变储能材料;运用扩散-渗出圈法确定了膨胀珍珠岩的最佳吸附量为65%（质量分数,下同）;采用DSC及SEM对最佳吸附量的石蜡/膨胀珍珠岩复合相变储能材料的相转变过程及微观结构进行研究。结果表明：膨胀珍珠岩的内部孔隙基本被石蜡完全填充,其自身成为了密实颗粒;复合相变储能材料的相变温度与石蜡的相变温度基本一致,其相变潜热与对应质量分数下石蜡的相变潜热相当。     

石蜡蓄热太阳能炕在北方农村住宅中的应用

本文针对北方农村地区的生活习惯设计了一套采用石蜡蓄热的太阳能采暖炕系统,不仅很好的利用太阳能这种清洁能源解决了炕的采暖问题,还可以在夏季提供部分生活热水。该太阳能炕系统中封装的石蜡由于其良好相变特性和较高的相变潜热,冬季供暖时段白天可在太阳能炕中续存一定的热量,晚上利用相变潜热释放的热量有效保证炕面温度,达到节能和提高舒适性的目的。对实际搭建的太阳能炕系统进行四个连续周期的测量表明,太阳辐照良好的情况下太阳能炕面平均温度可保证30~40℃的人体舒适性温度,具有很好的实际使用价值。     

表面张力估算低芳浅色矿物油的溶解度参数

通过表面张力估算法测定低芳浅色矿物油的溶解度参数。以溶解度参数定义为基础,结合溶解度参数实验经验公式和表面张力与液滴大小的关系,推导出表面张力与溶解度参数的拟合关系式。通过与11种含弱极性键的有机溶剂溶解度参数的文献值进行对比计算,得到溶解度参数的表面张力表达式的各个系数。利用溶解度参数表面张力表达式,计算29种常见的低芳浅色矿物油的溶解度参数。计算结果表明,29种低芳浅色矿物油的溶解度参数计算值为14.40~16.07(J/cm~3)~(1/2),经与文献值对比证明了拟合公式的准确性。     

脑组织双重免疫荧光标记方法介绍

应用光学技术对荧光标记的组织切片样品进行成像观察是生物学研究的常规手段。本文主要介绍如何制备用于荧光显微镜和激光共聚焦显微镜成像的脑组织石蜡切片免疫荧光双重标记技术。