五自由度机械臂的运动学分析

为分析机械臂的运动情况,建立基于D-H法机械臂正运动学模型并进行仿真,得到其灵活工作域。进一步采用ADAMS进行逆运动学分析,代替代数反解计算,可方便获得指定路径对应的各关节转角曲线。结果表明基于Matlab和ADAMS的运动仿真分析可为实际物理样机的研制提供技术依据。     

Multivariable wavelet finite element for flexible skew thin plate analysis

Flexible skew thin plate is widely used in mechanical engineering, architectural engineering and structural engineering. High-precision analysis is very important for structural design and improvement. In this paper, the multivariable wavelet finite element (MWFE) based on B-spline wavelet on the interval (BSWI) is constructed for flexible skew thin plate analysis. First, the finite element formulation is derived from multivariable generalized potential energy function. Then the generalized field variables are interpolated and calculated by BSWI. Different from the traditional wavelet finite element, the analysis precision can be improved because the generalized displacement and stress field variables are interpolated and calculated independently, the secondary calculation and the computational error are avoided. In order to verify the effectiveness of the constructed MWFE, several numerical examples are given in the end.     

Preparation and adsorption property of phenyltriethoxysilane modified SiO2 aerogel

The hydrophobic silica aerogel (SiO₂ aerogel) was prepared by in situ polymerization sol-gel method and ethanol supercritical drying, with tetraethoxysilane (TEOS) as silica source, phenyltriethoxysilane (PTES) as modifier, ethanol as solvent and ammonia as catalyst. The effects of n(PTES)/n(TOES) were investigated on gel time, structure, and hydrophobicity. The SiO₂ aerogel was measured by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of n(PTES)/n(TOES) were also studied on adsorption property of pentane, hexane, heptane, octane, benzene, toluene, o-xylene, nitromethane, nitroethane, and nitrobenzene. The adsorption intensity of SiO₂ aerogel was compared with that of activated carbon. The results show, with the increasing of n(PTES)/n(TOES), the surface area, pore volume, and pore size of SiO₂ aerogel decreased, gel time and hydrophobicity increased, and the contact angle could be 154° with n(PTES)/n(TOES)=0.7. The adsorption intensity of SiO2 aerogel with n(PTES)/n(TOES)=0.5 was bigger than that of activated carbon with an average 5.84 times of 10 organic liquid. The adsorption intensity of aerogel with n(PTES)/n(TOES) =0.1 was the best one in all samples with the average 8.33 times compared with that of activated carbon.     

Degradation mechanism of lacquered tinplate in energy drink by in-situ EIS and EN

The corrosion process of phenolic epoxy coated tinplate in energy drink was investigated by in-situ electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) techniques. The experimental results indicate that the degradation process of novolac epoxy coated tinplate in energy drink can be divided into three main stages: organic coating wetted by the beverage; corrosion initiation beneath the organic coating; and corrosion extension process. It was proposed that the tin coating and carbon steel were mainly corroded by organic acids in energy drink through the pores of the organic coating. After the tin coating was corroded, the carbon steel started to corrode due to its higher electrochemical activity and became to be the dominated corrosion reaction.     

中国股票市场定期定额投资策略实证分析

从定期定额投资的定义出发,对定期定额投资策略进行了数理分析,得到其收益率公式,总结了影响定期定额投资策略收益率的因素.通过对案例的实证分析,归纳出定期定额投资方式下确保获利的投资策略:寻找成长性良好的公司、按内在价值选择低成本股票、在跟踪公司成长性动态的基础上坚持长期投资.一般情况下定期定额投资方式不一定能确保获利,本...     

数字博物馆中的图像版权保护研究

随着数字博物馆的不断发展,关于数字博物馆中的图像版权保护越来越受到人们的重视。首先对数字水印技术和数字博物馆进行介绍,然后就数字水印技术用于解决数字博物馆中图像版权保护问题进行探讨,提出一种新的基于奇异值分解的盲数字图像水印算法。利用Arnold混沌映射将水印进行预处理,并按水印的大小把原始图像分成若干个子块,利用矩阵的奇异分解方法分解每个子块,通过比较调整相邻图像块最大奇异值来完成水印的嵌入。实验结果表明,该算法对于JPEG有损压缩、剪切、加噪声等攻击具有很强的鲁棒性。     

Android下OpenMax IL框架的研究和应用

由于Android系统多媒体引擎使用的是OpenMax软件解码组件,出现了播放分辨率较高视频不流畅的问题。为此,提出在Android系统上设计一OpenMax硬件解码组件,并将其放在嵌入式开发平台上进行测试。该组件是在对Android系统自带Open-Max IL层进行研究的基础上,以SamSung S3C6410为嵌入式核心处理器,针对MPEG-4视频流而设计。实验结果表明,设计的硬件解码组件优于系统自带的软件解码组件,表明该方案切实可行。     

面向数值模拟数据的HDF5性能优化

大规模数值模拟数据对可视化分析提出了挑战,I/O是影响可视化交互性能的重要因素.HDF5是科学计算领域广泛采用的存储格式,介绍了HDF5的抽象数据模型、数据读写流程,并使用典型数值模拟数据测试了HDF5的读性能.测试发现HDF5的数据集定位开销较大.根据数值模拟数据的数据块以整数有规律编号的特点,通过在HDF5中增加数据块视图对象来提高读性能.测试表明,该方法可显著加速数据的读取性能.     

一种基于模糊关联分类的遥感图像分类方法

遥感图像分类是遥感领域的研究热点之一.提出了一种基于自适应区间划分的模糊关联遥感图像分类方法(fuzzy associative remote sensing classification,FARSC).算法根据遥感图像分类的特点,利用模糊C均值聚类算法自适应地建立连续型属性模糊区间,使用新的剪枝策略对项集进行筛选从而避免生成无用规则,采用一种新的规则重要性度量方法对多模糊分类规则进行融合,从而有效地提高分类效率和精确度.在UCI数据和遥感图像上所作实验结果表明,算法具有较高的分类精度以及对样本数量变化的不敏感性,对于解决遥感图像分类问题,FARSC算法具有较高的实用性,是一种有效的遥感图像分类方法.     

基于B/S模式的交通卡口管理平台

采用B/S模式设计了一个交通卡口管理平台,依托卡口系统现有数据网络对监控图像进行网络传送,采用视频监控技术实现信息共享、远程监控和管理,能够为远端监控人员掌握第一手现场资料、做出正确决策提供强大的支持。