入侵检测系统

通过分析当前流行的入侵检测系统（Intrusion Detection Systems，IDS），详细地讨论了入侵检测系统的体系结构及其相关技术，主要包括系统的体系结构、数据采集方法、数据处理方式和具体的评价标准。研究结果表明，未来关于IDS的研究焦点应该是开发新的方法，它能以很低的误报率来检测新型攻击；未来工作的方向应该是扩展IDS和评价系统。     

The Phaeodactylum genome reveals the evolutionary history of diatom genomes

Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one-fifth of the primary productivity on Earth. The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology. Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes ( approximately 40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.     

The genome of the choanoflagellate Monosiga brevicollis and the origin of metazoans

Choanoflagellates are the closest known relatives of metazoans. To discover potential molecular mechanisms underlying the evolution of metazoan multicellularity, we sequenced and analysed the genome of the unicellular choanoflagellate Monosiga brevicollis. The genome contains approximately 9,200 intron-rich genes, including a number that encode cell adhesion and signalling protein domains that are otherwise restricted to metazoans. Here we show that the physical linkages among protein domains often differ between M. brevicollis and metazoans, suggesting that abundant domain shuffling followed the separation of the choanoflagellate and metazoan lineages. The completion of the M. brevicollis genome allows us to reconstruct with increasing resolution the genomic changes that accompanied the origin of metazoans.     

基于分级策略的自动人眼检测与定位

针对小波阈值法中的小波变换只能将图像分解到有限方向, 而不能较好地表征图像多方向性的问题, 用改进混合小波 方向滤波器组（HWD:Hybrid Wavelet Directional filter banks)变换代替单纯小波变换, 使在图像分解过程中更好地表征图像的多方向性, 保存更多的图像信息; 在分析小波阈值去噪原理的基础上,改变隶属度函数, 构建HWD隶属度的权系数, 从而避免因小波系数间存在幅值交叉使小波阈值法的应用受到限制。改进的HWD在损失最少图像小波系数的前提下, 能最大限度地置零噪声小波系数。实际工程图纸去噪研究表明, 改进的小波阈值法可在去除一定噪声的前提下, 保留更多的工程图纸细节信息。     

进展性动脉粥样硬化兔模型的建立方法

目的探究快速、有效地建立进展性动脉粥样硬化兔模型的方法。方法15只新西兰大耳白兔随机分为颈总动脉球囊损伤组（n=8）和假手术组（n=7）,两组均饲喂高脂饮食,14周后结束实验,对颈总动脉和其他血管节段（胸主动脉、主动脉根部和腹主动脉）作病理观察,计算内膜增生面积／内弹力膜围绕面积（％）、平均内膜厚度／内弹力膜围绕面积半径（％）和最大内膜厚度／内弹力膜围绕面积半径（％）,以评价斑块大小;确定病变组织形态学分型（美国心脏协会推荐）以评价斑块病变严重程度。测定实验前后的动物血脂水平。结果高脂喂养14周,在兔主动脉各血管节段中,斑块尺寸由大到小顺序：胸主动脉〉主动脉根部〉腹主动脉。胸主动脉虽在单纯高脂作用的各血管节段中斑块尺寸最大、病变进展最快,但仍主要停留在以内膜细胞外脂质池出现为特点的过渡性病变,较少发展至以脂质核心形成为特征的进展性病变。球囊损伤术使病变最轻微、进展最缓慢的颈总动脉斑块尺寸明显超过胸主动脉（P〈0．01）,并使其发展为进展性动脉粥样硬化病。结论在高脂饮食基础上,球囊损伤法能够快速、有效地建立以脂质核心形成为特征的进展性动脉粥样硬化病变兔模型,为进一步探究不稳定性斑块的形成机制及干预措施提供了适用的动物疾病模型。     

一种改进的基于能量控制并支持实时业务传输的ERT-AODV路由协议

AODV协议在建立路径时没有考虑节点能量,会导致网络中某些节点能量消耗过快而失效。提出一种改进的路由协议ERT-AODV,选择平均能量最大且节点最小残余能量高于门限值的路径进行通信,以平衡网络中的节点能量消耗、降低节点失效率,延长网络的生存时间;同时考虑到实时业务对延时的敏感性,通过设置定时器和扩大传输半径,可以有效的降低延时,仿真结果表明ERT-AODV在节点失效率和平均端到端延时方面比AODV更具优势。     

新型三分支环腔式自适应流入控制装置设计及数值模拟

水平井作为一种先进的钻井技术,已广泛应用在各种复杂的油气藏中,但水平井在开采底水油藏时面临着底水脊进的主要问题,早期的流入控制装置(ICD)和现在的自适应流入控制装置(AICD)通过均衡流入剖面控制底水脊进对水平井开采的影响,但都存在一定的局限性。本文在前人研究的流道型AICD的基础上,设计了一种三分支环腔式新型AICD控水装置并进行相应的优化设计,该装置结构简单,能够自动识别油和水,并能够根据油水性质差异对油和水产生不同的压降;利用ANSYS数模软件,对该装置进行仿真模拟和结构优化,优化结果为分支角为60°,入口个数为3时最优。最后进行敏感性分析,结果表明水流过该装置的压降远远大于油流过该装置时的压降;流体密度,黏度和含水率等参数对压降都有不同的影响,其中黏度的影响最大,密度的影响最小。     

曲线连续箱梁桥的偏心距及其对支座反力的影响

讨论圆弧曲线箱梁桥的偏心距及其对支座反力的影响.结果表明:内支座采用单支座布置的曲线连续箱梁桥可以通过改变支座的偏心距来调整支座的反力差.不同的支座布置形式合适的偏心距不同,并随着圆心角的增大而增大,边跨端部布置固定支座时偏心距较大,中间内支座采用墩梁固结时偏心距较小.