An image encryption scheme based on precision limited chaotic system

Multimedia Tools and Applications - In recent years, various chaotic maps have been used for image encryption. However, most of these image encryption algorithms entail a lot of floating-point...     

析湿工况下翅片管式换热器表面粉尘沉积过程的数值模型

空调器采用翅片管式换热器作为蒸发器，在制冷工况下换热器表面发生析湿及粉尘沉积，导致性能衰减。建立湿翅片表面粉尘颗粒物沉积过程的数学模型，模拟冷凝水捕集颗粒物以及湿积灰层黏附颗粒物的过程。被冷凝水捕集的颗粒物数量等于运动轨迹与水表面轮廓会出现相交的入射颗粒物的数量；后续的入射颗粒物与湿积灰层碰撞时，部分入射颗粒物会发生沉积且部分被碰撞的已沉积湿颗粒物会发生移除，这两部分的颗粒物数量相减即为被湿积灰层黏附的颗粒物数量。模拟与实验结果的对比表明，预测的湿积灰层形状与实验照片的吻合度较好，预测的单位面积颗粒物沉积质量与91%的实验数据之间的误差在±20%之间，平均误差为11.8%。     

Formation of a protective layer against corrosion on Mg alloy via alkali pretreatment followed by vanillic acid treatment

Although Mg alloy possesses high specific strength, low density, and good biocompatibility, poor corrosion resistance hinders its further applications. In the present study, an innovative protective layer against corrosion was prepared on the AZ31 Mg alloy via alkali pretreatment followed by vanillic acid treatment. The alkali pretreatment supplied –OH for the AZ31 Mg alloy surface to react with vanillic acid. The vanillic acid treatment played a crucial role in enhancing the corrosion resistance due to the excellent ability to act as a barrier and retard aqueous solution penetration, which effectively isolated the underlying Mg alloy from the corrosive environment. The corrosion current density of alkali and vanillic acid-treated Mg alloy (AZ31V) almost showed two orders of magnitude lower values in comparison with that of the AZ31 Mg alloy, and the corrosion potential of AZ31V Mg alloy increased from −1.41 to −1.25 V. The immersion tests proved that there was no occurrence of severe corrosion. Hence, the alkali pretreatment and vanillic acid treatment may represent a promising method to improve the corrosion resistance of Mg alloy.     

智能变电站设备管控大数据分析系统研究

结合数据挖掘、大数据技术在电力系统中的应用现状，分析和设计了一种智能变电站设备管控大数据分析系统。对变电站设备运行状态的大数据特征及基本框架进行了分析，并重点阐述了变电站设备运行状态大数据分析系统的数据集成与预处理、数据存储与处理、设备状态评估模型以及数据可视化展示。实验结果表明，所设计的大数据分析系统能够大幅度提升变电站设备数据分析智能化水平，为变电站管控稳定运行提供更加有效和实用性的技术支撑。     

Effect of ultrasonic vibration on thermal and material flow behavior,microstructure and mechanical properties of friction stir welded Al/Cu joints

Al/Cu dissimilar joint has been widely produced by using friction stir welding (FSW), but the weld quality remains limited. A recently developed ultrasonic     

某露天矿山边坡结构参数优化与支护设计

某露天矿山东帮边坡稳定性较差,已有12个区域出现大面积滑坡或垮塌,导致东帮边坡部分平台不连通,给矿山生产造成了严重的安全隐患。基于此,以边坡安全系数控制值为边坡稳定评判标准,采用极限平衡法、Geo-Slope软件计算边坡安全系数,分析边坡整体与局部的稳定性,并对不稳定区域进行参数优化研究,结果表明:东帮边坡整体滑坡的概率较低,但局部稳定性较差,需采取防护措施;边坡结构参数经优化后,边坡整体处于稳定状态。     

Tensor Q-rank: new data dependent definition of tensor rank

Machine Learning - Recently, the $${ Tensor}~{ Nuclear}~{ Norm}~{ (TNN)}$$ regularization based on t-SVD has been widely used in various low tubal-rank tensor recovery tasks. However, these models...     

Transformation of the reabsorption characteristics of lignite treated by low and high temperature drying process

Abstract

The reabsorption characteristics of the lignite treated by low and high temperature drying process were addressed in the paper. The information about the moisture form, functional groups, effective water-filled porosities and equilibrium moisture content of the lignite before and after the drying process was investigated using Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and a self-made reabsorption device, respectively. The results show that the low drying temperature (140, 190, 230?°C, 10?min, N₂) has little impact on the effective water-filled porosities of the resulted samples, whereas it has a great influence on the main oxygen-containing functional groups, which amount firstly decreases and then increases with the drying temperature increasing. In the case of the lignite samples dried under high-temperature (600, 700, 800?°C, 30?s, N₂), the amount of the effective water-filled porosity of the sample decreases and the amount of oxygen-containing functional groups increases as the temperature increasing. The reabsorption capability of the high temperature dried sample is much lower than that of the sample treated under low drying temperature. The reabsorption characteristics of the low-temperature dried samples are affected by the amount of the oxygen-containing functional groups, while the effective water-filled porosity is main factor for the lignite samples derived from high temperature drying process. Moreover, the work gives a good evidence that the high-temperature drying process is an effective choose for lignite upgrading.