微震定位系统中拾震器布阵研究

对微震监测中拾震器阵列进行科学有效的布置是保证微震定位系统能有效运行的一个关键条件,设计了4种拾震器阵列布设方案,使煤矿中微震定位监测系统运行得更加科学有效.首先建立复杂地质模型,利用微变网格射线追踪正演模拟出微震源起震到拾震器阵列接收信号的过程,然后在施加随机扰动的情况下,利用粒子群-神经网络算法(PSO-BP)反演推算出震源位置,最后通过震源位置的误差来分析各个布阵方案的特点,同时分析了阵列中拾震器数量的合理值.研究结果表明,在微震监测系统中拾震器利用率最高的情况下,可以给出准确、合理、有效的拾震器布阵方案.     

Pure spatial rich model features for digital image steganalysis

The SRM (Spatial Rich Model) is a very effective steganalysis method. It uses statistics of neighboring noise residual samples as features to capture the dependency changes caused by embedding. Because the noise residuals are the high-frequency components of image and closely tied to image content, the residuals of different types of image regions have different statistical properties and effectiveness for steganalysis. In this paper, the effectiveness of the residuals is investigated. Then the effectiveness of the statistics collected from different types of neighboring residual samples is investigated from the FLD (Fisher Linear Discriminant) viewpoint, and ineffective, effective and high-effective neighboring residual samples are defined. The ineffective neighboring residual samples are not likely to change during embedding, and if they are counted in statistics, they may mix the features with noise and make the features impure. Pure SRM features are extracted based on neighboring noise residual sample selection strategy. Furthermore, multi-order statistical features are proposed to increase the statistical diversity. Steganalysis performances of the statistical features collected from different types of neighboring residual samples are investigated on three content adaptive steganographic algorithms. Experimental results demonstrate that the proposed method can achieve a more accurate detection than SRM.     

Complex-query web image search with concept-based relevance estimation

Complex queries are widely used in current Web applications. They express highly specific information needs, but simply aggregating the meanings of primitive visual concepts does not perform well. To facilitate image search of complex queries, we propose a new image reranking scheme based on concept relevance estimation, which consists of Concept-Query and Concept-Image probabilistic models. Each model comprises visual, web and text relevance estimation. Our work performs weighted sum of the underlying relevance scores, a new ranking list is obtained. Considering the Web semantic context, we involve concepts by leveraging lexical and corpus-dependent knowledge, such as Wordnet and Wikipedia, with co-occurrence statistics of tags in our Flickr corpus. The experimental results showed that our scheme is significantly better than the other existing state-of-the-art approaches.     

光伏微逆变器电流传感器和功率管开路故障诊断

当电流传感器出现性能蜕化、故障或失效时,光伏微逆变器系统的输出会受到严重影响,甚至微逆变器系统其他部件有可能被直接损坏而导致整个系统永久失效;微逆变器系统中反激式变换器功率管的开路故障会引起2个交错支路电流不平衡,导致输出电流波形畸变率变大.为此,提出一种基于状态观测器的光伏微逆变器电流传感器和功率管开路故障诊断方法.建立两路反激式变换器的数学模型;构建状态观测器以实现对两路反激式变换器原边电流的在线估计,并生成残差;将残差与阈值进行比较,实现对微逆变器系统中电流传感器与功率管的实时故障诊断.仿真结果验证该方法可行且有效.     

核酸适体靶向红荧烯有机纳米探针用于肿瘤成像研究

近二十年来,肿瘤在我国的发生率和死亡率呈现不断增高的趋势。若能早期发现癌变位点并及时对其进行靶向治疗,将有助于提高癌症的治愈率。伴随着纳米技术的发展,用于癌症早期诊断成像和治疗的纳米材料的开发也得到了人们的广泛关注。文章介绍了一种基于核酸适体靶向肿瘤细胞的有机荧光纳米探针,其制备过程快速简便,所制得的纳米颗粒不仅表现出优异的靶向能力,而且具有良好的生物相容性和稳定性,该研究为肿瘤的靶向诊疗提供了有力工具。     

盲分离中LMS和RLS两种算法的比较

盲源分离试图从给定的一组混合观察数据中恢复未知的独立信源：本文简要阐述LMS和RLS两种自适应算法,用Matlab对一组混合通信信号进行分离实验,考察算法的特性和效果,并进行比较分析。结果表明：LMS算法与RLS算法相比,RLS算法的收敛性能更好一些,而在RLS算法中,自然梯度RLS法又是最优的。     

浅谈云计算的安全

从云计算出现,相关云计算的服务纷纷出现,伴随而来的就是云计算的安全问题。云计算安全的策略构想是:使用者越多,每个使用者就越安全,因为庞大的用户群体,足以覆盖互联网的每个角落,这要某个网站被木马病毒概念股及,就立刻会被捕获。云安全发展迅速,工信部和国家发改委在2010年在北京,上海深圳,杭州,无锡等五个城市先行开战云计算服务创新发展的试点工作。     

面向微小型机器人的5.8GHz微波能量传输系统

提出了面向微小型机器人的5.8 GHz 微波能量传输系统,采用Ritz-Galerkin（RG）方法建立了微波能 量传输系统射频整流电路模型,分析了整流二极管的整流性能,得到了输入功率与输出电压、整流效率与负载比之 间的关系．设计了八木振子天线,提高了能量接收的定向性．最后搭建了微小型机器人微波能量传输实验系统,开 展了利用微波传输能量驱动微机器人的实验,验证了利用微波能量传输系统为微小型机器人供能的可行性．     

数据挖掘在移动通信中的应用

简单介绍了数据挖掘技术,数据挖掘所需要的条件、数据仓库的建立,以及移动通信中经常用的两种算法：决策树算法和K最近邻算法,并较为详尽地阐述了它们的工作原理。     

新型复合FRP锚杆的延展性及协调性数值分析

针对岩土锚固系统中单一材料纤维增强复合材料（Fiber Reinforced Polymer,FRP）锚杆固有的脆性特征以及延展性较差的问题,提出新型复合FRP锚杆——MFRP（Metal FRP）锚杆.该锚杆由中心的高延展性金属材料、外层的FRP以及连接金属材料和FRP的钢纤维层构成.根据复合材料混合法理论分析MFRP锚杆的延展性,并用MSC Marc模拟分析其协调性.MFRP的应力应变曲线及锚杆受拉力情况下界面剪应力表明：MFRP的延伸率比普通的FRP提高大约15倍;通过添加钢纤维层,MFRP的界面平均剪应力比未添加钢纤维层的材料减小一半左右,从而使界面间的变形更加协调.