融合词袋连通图的图像检索特征选择

目的 随着图像检索所依赖的特征愈发精细化,在提高检索精度的同时,也不可避免地产生众多非相关和冗余的特征。针对在大规模图像检索和分类中高维度特征所带来的时间和空间挑战,从减少特征数量这一简单思路出发,提出了一种有效的连通图特征点选择方法,探寻图像检索精度和特征选择间的平衡。方法 基于词袋模型（bag of words,BOW）的图像检索机制,结合最近邻单词交叉核、特征距离和特征尺度等属性,构建包含若干个连通分支和平凡图的像素级特征分离图,利用子图特征点的逆文本频率修正边权值,从各连通分量的节点数量和孤立点最近邻单词相关性两个方面开展特征选择,将问题转化为在保证图像匹配精度情况下,最小化特征分离图的阶。结果 实验采用Oxford和Paris公开数据集,在特征存储容量、时间复杂度集和检索精度等方面进行评估,并对不同特征抽取和选择方法进行了对比。实验结果表明选择后的特征数量和存储容量有效约简50%以上;100 k词典的KD-Tree查询时间减少近58%;相对于其他编码方法和全连接层特征,Oxford数据集检索精度平均提升近7.5%;Paris数据集中检索精度平均高于其他编码方法4%,但检索效果不如全连接层特征。大量实验表明了大连通域的冗余性和孤立点的可选择性。结论 通过构建特征分离图,摒弃大连通域的冗余特征点,保留具有最近邻单词相关性的孤立特征点,最终形成图像的精简特征点集。整体检索效果稳定,其检索精度基本与原始特征点集持平,且部分类别效果优于原始特征和其他方法。同时,选择后特征的重用性好,方便进一步聚合集成。     

计及风电场侧谐波阻抗影响的谐波发射水平评估

风机滤波器和无功补偿装置导致风电场侧谐波阻抗并非远大于系统侧谐波阻抗,因此在计算风电场侧谐波电压发射值时,不可忽略风电场侧谐波阻抗的影响。提出一种基于改进复线性回归方程的风电场谐波发射水平评估方法。从公共连接点(PCC)谐波电压中分解出与回归方程系数无关的风电场谐波电流分量,据此建立复线性回归方程,采用复最小二乘法计算系统侧谐波阻抗,计及风电场侧谐波阻抗计算风电场侧谐波发射水平。针对风电场集电网络拓扑结构的多变性,提出一种集电网络聚合等值方法,将混联结构的集电网络聚合为T形结构的网络计算风电场侧谐波阻抗,并利用分散参数的误差边际效应对误差进行分析。仿真和实测数据验证了所提方法的有效性。     

Synthesis and characterization of Sb-doped SnO2 with high near-infrared shielding property for energy-efficient windows by a facile dual-titration co-precipitation method

Sb-doped SnO₂ (ATO) powders were favorably synthesized using a dual-titration co-precipitation method for the application of energy-efficient windows. A dual-titration co-precipitation method can effectively inhibit the aggregation of primary nanoparticles, which is conducive to prepare stable dispersion applied to glazing materials for blocking part of solar radiation. Various annealing temperatures, doping molar ratios and ethanol content of precursor solution were used to investigate the influence on the morphology and phase composition of the as-synthesized ATO powders. The results illustrated that the reasonable reaction conditions to prepare ATO powders with near-infrared shielding property should be: the doping molar ratio of 10%, the content of ethanol in precursor solution of 100% and the annealing temperature of 1000 °C. Besides, ATO primary nanoparticles were gained ranging from 45 to 55 nm with a low aggregated degree. The ATO coating prepared by the ATO dispersion with 20 wt% demonstrated the optimal selective transmitted spectra, which simultaneously achieved the average visible transmittance of 80.15% but average near-infrared transmittance of 23.31%. In addition, a simulated experiment demonstrated that ATO coated glass exhibited a better near-infrared shielding property than ITO (Sn-doped In₂O₃) coated glass.     

Titania-silica composites with less aggregated particles

Less aggregated titania-silica composite was developed by a versatile and reproducible method using relatively cheap precursors. The final product has more suitable properties than the conventional materials. The composite was synthesized by using sodium silicate, as a silica precursor, and freshly prepared TiOCl₂ as a titania source. The final product was obtained after subsequent calcination for 5 h at 300 to 1000 °C. The primary particles of the composite, as examined by SEM technique, are generally less aggregated. The XRD patterns for the calcined samples indicate the presence of TiO₂ and there is a significant increase of peak intensity as the calcination temperature increases. EDS and XPS analyses confirmed the formation of pure composite rich in Ti, Si, and O. Nitrogen physisorption studies reveal that the composite is mesoporous and have large BET surface area (~ 375 m²/g). A simple experiment of photoreduction of methyl orange under solar radiation was attempted to demonstrate the reliability and improvement of titania-silica composite in practice. It was found out that its efficiency is high as compared to P-25 TiO₂ under solar light. The results demonstrate that composite with desirable properties for various applications can be obtained via the present route.     

基于多agent的聚合级CGF系统的体系结构研究

文章在简要分析CGF系统一般原理的基础上,构建了一种基于多agent的聚合级CGF系统的体系结构,对a gent的结构、各agent的功能、agent间的通讯、agent的工作过程等问题进行了较为详细的阐述。     

Aggregated Markov-based reliability analysis of multi-state systems under combined dynamic environments

Reliability of a system may differ greatly when operating under different environments. However, the existing works have either neglected the environment factor in system reliability analysis or considered this factor for binary systems or systems subject to a single environment (parameter). In this paper, we make contributions by modeling a multi-state system operating under hybrid dynamic environments affected by multiple environmental parameters. Different Markov chains with finite states are used to represent the random system behavior and dynamic environments, leading to an aggregated Markov process that models the overall system behavior. An effective approach based on state partitions and aggregations is suggested for assessing the system reliability indexes, including reliability, availability, multi-point availability, and environment-based reliability. A high-pressure homogenizer system is analyzed to demonstrate the proposed model and show the comparison of the reliability of system under fixed and dynamic environment.     

冶金工业主题词表词间等级关系的研究

介绍了《冶金工业主题词表》编制过程中叙词等级关系的种类，提出了等级关系的构建原则，重点分析了等级关系的构建方法及典型案例。得出如下结论：正确理解等级关系的构建原则是建立等级关系的前提条件；对专业知识的准确把握对于建立叙词等级关系至关重要；对于不甚熟悉的概念，需要参考有关工具书；对于原有专业叙词表，要采取批判的态度进行继承。