离散小波变换Haar-LL的行人检测研究

提出一种基于二维离散Haar小波变换的局部二值模式(LBP)与局部梯度模式(LGP)的特征融合方法。对图像进行二维离散Haar小波变换,得到4个不同频率的子图像,对低频部分子图像提取LBP特征,对3个高频部分子图像提取LGP特征,将3个LGP特征并接融合后与LBP特征串接融合进行行人检测。在Matlab环境下利用支持向量机(SVM)对INRIA数据集进行5组实验,分别将该方法与梯度方向直方图(HOG)、金字塔梯度方向直方图(PHOG)、LBP、LGP进行检测率、检测时间、光照鲁棒性以及噪声鲁棒性对比。综合各项实验数据表明,该方法在光照鲁棒性以及噪声鲁棒性方面都能取得更好的效果。     

结合小波变换的梯度场图像渐进融合算法

基于梯度场的图像融合算法只适用于尺度差异不大于1∶4的多光谱图像与全色图像。针对尺度差异为1∶8的北京一号卫星多光谱图像及高分辨率全色图像的融合问题,提出一种结合小波变换的梯度场图像尺度渐进融合算法。利用小波变换方法将多光谱图像与高分辨率全色图像尺度差异倍数缩小,得到基于小波变换的初级融合,再进行基于梯度场的Poisson图像融合。实验结果表明,渐进融合图像与多光谱图像的平均颜色差异值为23.5,与高分辨率全色图像的平均梯度差异值为2.1,多尺度纹理特征值差异值分别为3.98、10.2、18.9,渐进融合图像与高分辨率全色图像的空间细节和纹理细节吻合程度更好。     

钛酸铝材料研究进展及应用

钛酸铝是一种优异的高熔点、低膨胀无机非金属材料。主要阐述了钛酸铝材料的微观结构，以及热分解、热膨胀及其影响因素。简述了钛酸铝材料的制备方法。讨论了合成的工艺条件及添加剂对钛酸铝材料性能的影响，并对其应用作了简单介绍。最后提出了改善钛酸铝材料性能的技术途径。     

1,4-二硝基咪唑的合成及其热分解

用二步反应合成1,4-二硝基咪唑(1,4-DN I),即先用乙酸酐对4-硝基咪唑3位上的N进行N-酰化,再通过硫酸-乙酸酐-硝酸钠混合液对酰化产物进行硝化合成1,4-二硝基咪唑,通过正交实验对合成工艺进行了优化,得到了较优的工艺条件:4-硝基咪唑、浓硫酸、硝酸钠、乙酸酐的摩尔比为2∶3∶8∶15,反应温度30~40℃,反应时间3 h。用DSC研究了1,4-DN I的热分解。     

Catalytic characteristics of various rubber-reinforcing carbon blacks in decomposition of methane for hydrogen production

Carbon black has recently been reported to act as an effective catalyst for methane decomposition and to exhibit stable catalytic behavior despite carbon deposition, and thus it can be used for CO₂-free production of hydrogen from natural gas. In this work, various carbon blacks with different primary particle size were investigated with respect to methane decomposition under atmospheric pressure from 1123 to 1223 K. Catalytic characteristics, such as activity, activation energy and reaction order, were investigated and compared. It was observed that with decreasing primary particle size (or increasing specific surface area), the specific activity increased and the activation energy decreased. The reaction orders for various pelletized, rubber-reinforcing carbon blacks were 0.6–0.7, about the same regardless of the primary particle size, while they were near 1 for fluffy carbon blacks. Fluffy carbon black showed higher activity and activation energy than the pelletized carbon black of the same primary particle size. Changes of the surface morphology during carbon deposition were observed by TEM. Variations of the number of active sites were discussed in regard of the primary particle size, carbon deposition and binder. The presence of different types of active sites was also suggested.     

C207铜基催化剂常压甲醇分解反应动力学(Ⅰ)本征动力学模型

在直流流动积分反应器中常压下研究了C207催化剂甲醇分解反应本征动力学。实验温度、气体组成与甲醇合成工业条件相接近。以实验測定数据应用改进高斯-牛顿法对动力学模型参数进行估值,获得甲醇分解反应本征动力学方程。     

交替惩罚三线性分解二阶校正荧光分析法快速测定牛奶中洛美沙星含量

笔者利用化学计量学交替惩罚三线性分解二阶校正算法结合荧光分析,在有干扰药物及牛奶中干扰组分共存下,对牛奶中的洛美沙星进行快速分析测定。当三维荧光数据的预估组分数取4时,所得平均回收率达到99.4%±1.3%,预测方差均方根(RMSP)为2.97nmol/L,预测结果良好。实验结果表明,此法可用于干扰组分共存下牛奶中洛美沙星的快速定量测定。     

Textural properties evolution of Ir and Ru supported on alumina catalysts during hydrazine decomposition in satellite thruster

Ir/Al₂O₃, Ru/Al₂O₃, and Ir-Ru/Al₂O₃ catalysts with total metallic contents of 30% in mass were prepared by an incipient wetness method. The characterization of these materials, before and after their use for hydrazine decomposition in a satellite thruster, was performed by measurement techniques of specific surface area, volume and pores size distribution, H₂ chemisorption, TEM and basic chemical analysis. An average decrease of 11% in the BET surface area was observed, independent of the catalyst composition. The total specific pore volume remained unchanged because the volume reduction in the size range diameters between 1.0 and 10 nm was compensated by the increase in the diameters size range between 10 and 100 nm. A reduction of the H₂ quantity adsorbed on the Ir/Al₂O₃ catalyst can be explained by the metal loss through erosion as well as by its partial occlusion within the pores of the alumina support. On the other hand, catalysts containing Ru showed an increase of H₂ chemisorbed amount, attributed to a more complete reduction of this material after hydrazine decomposition, in spite of the erosion and occlusion losses. Such observations were confirmed by TEM, which showed a great stability of the distributions of the metallic particle sizes in all catalysts.     

Thermal stability of morpholine additive in the steam-water cycle of CANDU-PHW nuclear power plants

The thermal decomposition of morpholine, an additive used in the steam-water cycles of nuclear power plants, was studied using a laboratory high-pressure reactor. The measured decomposition rate constants are 2.67, 8.73 and 21.25 × 10^?7 s^?1 at 260, 280 and 300°C respectively. The kinetics were found to be first-order and the activation energy was 131.9 kJ/mol. Ammonia, ethanolamine, 2-(2-aminoethoxy) ethanol, methylamine, ethylamine, ethylene glycol, and acetic and glycolic acids were identified as the major breakdown products. The decomposition route proposed was validated in the field by tracking these breakdown products in water samples taken at Gentilly 2 power plant.     

一种结合主题模型的推荐算法

针对传统协同过滤推荐算法存在的冷启动、数据稀疏以及相似度度量的准确性问题,基于LDA主题模型对文本隐式主题挖掘的有效性和KL散度在主题分布相似性度量的准确性,提出了结合LDA主题模型的矩阵分解推荐算法。首先,利用改进的LDA算法输出项目-主题分布,并用困惑度作为主题数设置的修正函数;然后分别基于余弦相似度和KL散度计算得到项目相似度矩阵,将得到的相似度矩阵结合原评分训练集输出预评分,再将预评分填充到训练集;最后将训练集输入ALS矩阵分解算法得到推荐结果。通过MovieLens数据集的实验结果表明,该算法在不同隐式参数设定下均能得到比ALS推荐算法以及更小的预测误差,并且最优预测误差小于传统推荐算法。该实验说明了通过集成LDA主题模型的ALS算法效果要优于其他推荐算法。