地方时与区时在电离层研究中的差异

本文指出混淆地时与区时两个时间概念在电离层研究中带来的差异的严重性，建议使用地方与区时这两个名词，而抛弃“本地时”和“当地时”等容易引起混淆的名词。     

A low distortion image enhancement scheme based on multi-resolutions analysis in next generation network

With the advent of Next Generation Network (NGN), services that are currently provided by multiple specific network-centric architectures. NGN provides AAA (Anytime, Anywhere and Always on) access to users from different service providers with consistent and ubiquitous provision of services as necessary. This special issue of NGN includes pervasive, grid, and peer-to-peer computing to provide computing and communication services at anytime and anywhere. In fact, the application of NGN includes digital image processing, multimedia systems/services, and so on. Here we focus on the digital image processing technology in NGN environments. Low-contrast structure and heavy noise in NGN environments can be found in many kinds of digital images, which makes the images vague and uncertainly, especially in x-ray images. As result, some useful tiny characteristic are weakened—which are difficult to distinguish even by naked eyes. Based on the combination of no-linear grad-contrast operator and multi-resolution wavelet analysis, a kind of image enhancement processing algorithm for useful tiny characters is presented. The algorithm can enhance the tiny characters while confine amplifying noise. The analysis of the results shows that local regions of the image are enhanced by using the concept of the grad contrast to make image clearer adaptively. Experiments were conducted on real pictures, and the results show that the algorithm is flexible and convenient.     

IETM技术在便携式工卡系统中的应用研究

从飞机制造的角度出发,以IETM技术为基础,以带Windows 7操作系统的便携式终端为硬件平台,研究开发应用于某机机载机电设备装配指导的交互式电子工卡系统。文中主要介绍了系统设计的背景知识、开发架构和软硬件实现方法,结合XML和SQL数据库技术创作符合GJB6600标准的应用系统。该系统的成功研制和投入使用可将电子信息技术的最新研究成果用于生产实践,既可有效地减轻生产一线工作人员的劳动强度,又能极大地提高飞机数字化制造效率。     

一种检测单晶炉热场温度的新方法

为去除单晶炉热场温度测量信号中的低频干扰、提高温度信号的估计精度,本文提出了一种基于跨维模拟退火(trans dimensional simulated annealing,TDSA)的单晶炉热场温度检测方法.该方法首先将AIC(Akaike information criterion)信号个数判断准则纳入采样机制中以便对干扰个数采样估计,进而利用所设计的基于信号频谱和轮盘赌思想的Metropolis Hastings机制对相应个数的干扰频率进行采样,最后设计了混合均匀和高斯采样机制对单晶炉热场温度进行采样估计.仿真和单晶炉工程实验结果表明,该方法在干扰个数未知的情况下,能够有效地抑制低频干扰、准确检测单晶炉热场的温度.     

分流叶片对离心泵内部固液两相流的影响

为了研究分流叶片对离心泵内部固液两相流的影响,建立固液两相流模型,对无分流叶片离心泵和3种带分流叶片的离心泵进行全流道非定常数值模拟。重点分析了添加分流叶片对离心泵外特性、叶片表面压力脉动、叶片表面颗粒体积分数分布、叶片表面颗粒滑移速度的影响。分析结果表明:添加分流叶片以后,离心泵的扬程和效率均有显著的提高,叶片表面的颗粒分布更加均匀,叶片表面颗粒的滑移速度有不同程度的下降,使颗粒对叶片表面的磨损程度得以降低;当分流叶片的进口直径为0.65D2时,叶片出水边处的压力脉动幅值最小,减小了离心泵在运行过程中的振动和噪声。     

Laplacian group sparse modeling of human actions

Recently, many local-feature based methods have been proposed for feature learning to obtain a better high-level representation of human behavior. Most of the previous research ignores the structural information existing among local features in the same video sequences, while it is an important clue to distinguish ambiguous actions. To address this issue, we propose a Laplacian group sparse coding for human behavior representation. Unlike traditional methods such as sparse coding, our approach prefers to encode a group of relevant features simultaneously and meanwhile allow as less atoms as possible to participate in the approximation so that video-level sparsity is guaranteed. By incorporating Laplacian regularization the method is capable to ensure the similar approximation of closely related local features and the structural information is successfully preserved. Thus, a compact but discriminative human behavior representation is achieved. Besides, the objective of our model is solved with a closed-form solution, which reduces the computational cost significantly. Promising results on several popular benchmark datasets prove the efficiency and effectiveness of our approach.     

Detecting changes of the Yellow River Estuary via SAR images based on a local fit-search model and kernel-induced graph cuts

The Yellow River Estuary area of China is under great pressure from both human intervention and natural processes. For analysis of the changes in this area, this article presents a novel change-detection method based on a local fit-search model and kernel-induced graph cuts in multitemporal synthetic aperture radar images. Change detection involves assigning a label to every pixel. This task is naturally formulated in terms of energy minimization, which can be effectively solved by graph cuts. The difference image is transformed implicitly by a kernel function so that an alternative to complex modelling of the original data makes the piecewise constant model become applicable for graph cuts formulation. An issue is that graph cuts are sensitive to the initial estimate. The local fit-search model is proposed to approximate to the local histogram while selecting an optimal threshold for the initial labelling, which leads to an effective constraint for graph cuts and computational benefits as well. Visual and quantitative analyses obtained on the Yellow River Estuary data set confirm the effectiveness of the proposed method and that it outperforms the other state-of-the-art methods of change detection.     

高水头混流式水轮机内部固液两相流数值分析

针对泥沙直径对混流式水轮机蜗壳和导水机构内部流场产生影响的问题进行了初步研究,采用固液两相流模型对某电站的高水头混流式水轮机进行了全流道数值模拟,通过单一变量法来研究不同来流泥沙的直径对蜗壳和导水机构内部压力及泥沙分布产生的影响。研究结果表明:与清水相比,含沙水流会不同程度地使蜗壳和导水机构内部的水压力载荷增加,在相同工况下,蜗壳底部、蜗壳鼻端、固定导叶和活动导叶头部的泥沙浓度较大;小直径下泥沙分布均匀,随着泥沙直径的增加,泥沙浓度的梯度变大,泥沙分布更加集中,从而会使磨损加剧。该研究成果可为在含沙水流中运行的水轮机设计提供参考。     

基于逐次散射法的海洋-大气矢量辐射传输模式

首先推导了粗糙洋面双向偏振反射模型pBRDF(Bidirectional Polarized Reflectance Distribution Function),并将其与SOSVRT(Successive Order of Scattering Radiative Transfer)矢量辐射传输模式耦合,建立了海洋-大气耦合的矢量辐射传输模式,并对该耦合模式的模拟结果与前人模拟结果进行对比,验证了该耦合模式的可靠性与有效性。不同大气和洋面状态、不同高度的主平面内辐射强度和偏振度的模拟结果表明:pBRDF模型可以很好地模拟不同风速下洋面的偏振反射分布特征;洋面在特定角度具有很高的偏振度,并对大气顶的偏振辐射有很大影响。因此,该耦合模式可以更准确地处理辐射光谱在海洋-大气两种介质间的传输问题,对矢量辐射传输、大气遥感问题的研究有重要意义。     

浅谈多媒体教学以信息管理中心为例

高职教育的特点就是以适应社会需要为目标、以培养技术应用能力为主线设计学生的知识、能力、素质结构和培养方案,毕业生应具有基础理论知识适度、技术应用能力强、知识面较宽、素质高等特点.以“应用”为主旨来构建课程和教学内容体系.