高性能局域网监测软件的设计

研究设计了一种利用遵循SNMP协议的高效软件MRTG来获取局域网网络节点状态信息的有效方法,并将流量负载以包括PNG格式图像的HTML文档方式提供给用户,以非常直观的形式显示流量负载,以便查明设备和网络的性能问题。     

DM3故障恢复技术研究

故障恢复是DBMS的重要组成部分。提出了一种基于Redo日志、Undo日志和检查点的系统故障恢复技术,并详细介绍了它在数据库系统DM3中的设计和实现,最后还给出了相应的恢复算法。     

一种无冗余的Web日志挖掘算法

Web日志挖掘是Web数据挖掘的一个重要研究领域。Web日志挖掘通过发现Web日志中用户的访问规律和模式,可以提取出其中潜在的规律和信息,人们对这个领域的研究也日益重视。然而,传统的基于关联规则的Web日志挖掘算法都是基于所有关联规则的。这种方式往往挖掘产生大量的候选规则,而且存在大量冗余的规则。提出了一种新的无冗余的Web日志挖掘算法,该算法通过引入频繁闭项集合最小关联规则的概念,从而解决了以往基于所有关联规则挖掘算法中出现的上述问题。     

Inverse resistivity problem: Geoelectric uncertainty principle and numerical reconstruction method

Mathematical model of vertical electrical sounding by using resistivity method is studied. The model leads to an inverse problem of determination of the unknown leading coefficient (conductivity) of the elliptic equation in R²$R^2$ in a slab. The direct problem is obtained in the form of mixed BVP in axisymmetric cylindrical coordinates. The additional (available measured) data is given on the upper boundary of the slab, in the form of tangential derivative. Due to ill-conditionedness of the considered inverse problem the logarithmic transformation is applied to the unknown coefficient and the inverse problem is studied as a minimization problem for the cost functional, with respect to the reflection coefficient. The Conjugate Gradient method (CGM) is applied for the numerical solution of this problem. Computational experiments were performed with noise free and random noisy data.     

面向数据挖掘的教学系统的设计与实现

由于数据挖掘技术具备从大量数据中提取特定数据模型的优势,已得到广泛的认可和应用。目前,数据挖掘在教育领域中应用的主要热点之一是如何构建面向数据挖掘的教学系统的研究。介绍一种面向数据挖掘技术的教学网站的设计思想和实现方法。该网站实现传统教学系统的通用模块,并增加对教学日志的支持功能。该功能为数据挖掘研究提供实验数据和实践平台。     

基于极坐标Log Gabor小波的纹理分析方法

提出一种基于极坐标Log Gabor小波的纹理分析方法,该方法突破了Gabor小波的带宽限制,仅采用较少的极坐标Log Gabor滤波器,即实现了准确地纹理分割.实验表明,在频谱覆盖相同的情况下,极坐标Log Gabor小波具有较Gabor小波更好的性能和更高的效率;此外,实验中针对多通道滤波方法对最小距离判别方法的改进,也取得了较好的效果,这为基于小波分解的分类问题提供了一个新的思路.     

日志审计系统设计与实现

根据目前的网络环境现状，提出了一个日志审计系统的设计，介绍了该系统的重要性以及它的作用，从总体上描述了系统的框架设计，同时对系统中大的功能模块进行了阐述，并利用伪代码给出了一些关键技术的实现细节，预见了日志审计系统在网络发展中的潜力。     

Evaluation of water content gradient using a new configuration of linear array four-point probe for electrical resistivity measurement

Electrical resistivity is used in this study to assess the moisture content of concrete, because of their good correlation. A new process using four point probes to measure the electrical resistivity of concrete is described in this paper. It is based on the exploitation of the short circuit induced by the reinforcement in the concrete structure. A numerical model is also made to simulate the resistivity measurements on concrete by taking into account the electrochemical parameters of the reinforcement. The obtained results have shown the ability of the new measurement process to assess the gradient of the moisture content of the concrete cover.     

Effect of Si substrate on ethanol gas sensing properties of ZnO films

We prepared ZnO/n-Si heterojunctions by depositing ZnO films on n-Si substrates with different resistivities by radio-frequency magnetron sputtering. The microstructure of ZnO film was analyzed by X-ray diffraction and scanning electron microscopy. The current-voltage characteristics and ethanol gas sensing properties of the junctions were investigated at room temperature. It is found that optimization of n-Si substrate resistivity is critical to enhance the ethanol gas sensitivity of ZnO/n-Si heterojunction. The ZnO/n-Si heterojunction with n-Si substrate of 2-3 Ω cm exhibits the best ethanol gas sensing property. The junction shows the sensitivity of 29.41% to 0.24 g/L ethanol gas under + 0.52 V forward bias voltage.