基于Top-K项频繁模式挖掘的研究及实现

频繁模式挖掘是关联规则、序列分析等数据挖掘任务的关键步骤,我们知道,当给定的最小支持度阈值非常小,将产生大量的频繁模式,反之,可能产生很少的模式或根本没有结果。用户有时仅对其中的部分项的频繁度感兴趣,这属于部分频繁模式挖掘问题。文章通过有效设置挖掘区间,讨论一种top—k项频繁模式挖掘问题,进而扩展到连续区间上的情况,最后将给出实验结果。     

一个基于误用检测的数据库安全审计系统

数据库审计是数据库安全的重要组成部分,包括日志记录和日志分析两部分。在SQL Server数据库中,使用审计功能只能获取审计跟踪的信息,并不具备日志分析的能力。针对SQL Server数据库审计功能的不足,给出了一个数据库安全审计系统MyAudit的设计和实现。MyAudit系统使用误用检测方法进行审计分析,能够检测出攻击企图、伪装攻击两种类型的数据库攻击。     

高速可配置Rijndael算法的设计与实现

针对网络通信的安全要求,给出了在集成电路设计中实现Rijndael算法的高吞吐率解决方案。对算法实现进行了优化,具有支持密钥长度和数据长度的可变选择与组合配置,加密和解密工作通道完全独立,全双工安全高速通信等特点。已通过了FPGA的验证与电路实现。通过对比分析综合仿真结果,该实现相对于目前已知的实现方案在性能和速度上具有很大的优势。     

Windows平台下的文件夹美化程序设计

在Windows平台下文件夹可以在以下四个方面实现美化：文件夹提示语;文件夹图标;背景图片;文件名的颜色。给文件夹加上系统属性,在其下建立名为desktop.ini文件,存放设置参数,即可实现。     

Proteomic analysis of sera of asymptomatic,early‐stage patients with Wilson's disease

Wilson's disease (WD) is characterized by excessive accumulation of intracellular copper in liver and extrahepatic tissues, leading to significant oxidative stress and tissue damage. To date, several diagnostic biomarkers for WD such as serum ceruloplasmin, serum or urine copper levels and copper content in liver have been identified. However, these biomarkers may not be convincing for the diagnosis in some WD patients. To identify additional novel diagnostic biomarkers, we compared the serum protein profiles of asymptomatic childhood WD patients (n=20), without neurologic manifestation or liver cirrhosis, with normal controls (n=13). Fourteen spots, five up‐regulated and nine down‐regulated (>2‐fold), were differentially expressed in WD patients in comparison to normal control on 2‐DE. Among them, three spots were down‐regulated in both male and female WD. MS/MS analysis revealed that the three spots were complement component C3, complement factor B and alpha‐2 macroglobulin. By comparative proteome analysis, complement component C3, complement factor B and alpha‐2 macroglobulin, which are related to oxidative stress and inflammation, turned out to be good candidates for novel diagnostic biomarkers for early stages of WD.     

Cytotoxicity of aggregated fullerene C60 particles on CHO and MDCK cells

The cytotoxicity of fullerene C60 particles on two mammalian cell lines, i.e. the Chinese hamster ovary (CHO) cells and the Madin-Darby canine kidney (MDCK) cells, has been investigated. Although innate fullerene particles have a very low solubility in deionized (DI) water, these particles can be dissolved in the tetrahydrofuran (THF) solvent at a great value. Further, the dissolved fullerene particles in the THF solvent could be extracted into a DI water solution at a significantly increased solubility. The formation of fullerene particle aggregates is believed to be the cause of the increased solubility. Results presented here show that once the concentration of the fullerene aggregates reaches a certain level, the cells start to die. The lethal dosage LD50, which is defined as the lowest fullerene concentration that results in a 50% cell death within 24 h, has been determined. Furthermore, the percentage of cell mortality increased with increasing fullerene concentration and incubation time yielding a negative effect on cell viability. These results, illustrated by atomic force microscopy (AFM), dynamic light scattering (DLS) and other microscopic techniques, will help to better understand the side effects of fullerene particles in mammalian cells.     

嵌入式技术在河水含沙量测量校准系统中的应用

针对河水含沙量测量校准设备的特点,基于ARM7嵌入式平台,本文设计了一种具有自适应能力的智能含沙量测量校准系统,经仿真、实践表明,其在一定的模型误差范围内具有良好的测量品质和鲁棒性.该系统有效地改善了含沙量测试设备的测量精度和稳定度,可为河流的治理及防灾、水处理工程等领域提供可靠的信息支持.     

PowerPC计算机系统级速度影响因素的研究

PowerPC处理器是目前使用最广泛的RISC处理器,设计基于PowerPC处理器高性能计算机的要求十分迫切。计算机系统结构中影响系统级速度的最主要因素为Cache状态、硬件等待数、编译系统以及操作系统。通过在基于PowerPC处理器的被测系统上使用典型算例,针对以上四个因素进行测试和研究,得到了硬件等待数、Cache状态、编译系统以及操作系统对系统级速度影响的数据,并给出测试结论和系统架构的设计建议。     

组合逻辑中瞬时错误传播的频域分析方法

提出一种新颖的频率分析方法来计算瞬时错误在组合逻辑电路中的传播．通过对输入信号进行傅里叶变换,分析组合逻辑电路的频率特性,并通过频域计算方法得到组合逻辑电路的输出．为了解决组合逻辑电路有时会工作在信号非线性区的问题,提出一种数学模型来精确描述瞬时错误在组合逻辑电路中传播过程．实验结果表明,该方法能保证在93％的平均精确度（和HSPICE相比）前提下,大幅提高评估速度．     

噪声测试平台的软硬件实现

为了提高噪声测试仪器使用效率,缩短测试周期,给出了一种噪声测试硬件平台的具体搭建方式及其配套软件的编写过程。硬件平台包括Agilent346C,HP8970B,HP8971C,HP8341B,Agilent82357A及GPIB连接线等。软件平台用Microsoft Visual C++6.0编程实现,通过GPIB接口对测试仪器进行控制,执行仪器校准、测量数据、将数据读入计算机,并能够将测试结果以文本和图形化方式显示出来,实现自动化测试。该噪声测试平台能够测量的最高频率为20 GHz。