分布式架构下的新型入侵检测系统研究

入侵检测(Intrusion Detection System,简称IDS)作为一个新兴的技术,成为原有的计算机安全体系很好的补充,正吸引越来越多的人参与到其研究中来.本文对分布式入侵检测系统进行了介绍,提出了一种基于数据挖掘以及分布式系统架构的入侵检测系统.并给出系统各个组件的设计,并对系统的实现框架进行了详细的阐述.最后指出本系统的特点.     

乙醇辅助碳氢燃料催化吸热反应

先进飞行器对燃料的冷却能力提出了苛刻的要求,迫切需要开发高性能吸热燃料和反应技术。基于醇类可以促进重油裂解提高低碳烯烃选择性的特性,提出乙醇辅助碳氢燃料催化吸热反应的研究设想。采用浆液涂敷法在高温合金管上制备了多种涂层催化剂,在电加热单管反应装置上评价了乙醇辅助碳氢燃料催化吸热反应性能。研究发现,在400~600℃的中低温条件下,乙醇可以在镍修饰的ZSM-5分子筛涂层催化剂作用下脱水生成乙烯,510℃时热沉提高约20%;在更高温度时,乙醇脱除的水可以参与蒸汽重整反应促进燃料吸热;而均相添加剂可以进一步与涂层催化剂协同作用,抑制结焦生成,将体系工作温度提升至791℃,获得3.71 MJ·kg^-1的热沉。     

基于早龄期超声测试的堆石混凝土工程质量检测EI北大核心CSCD

从早龄期开始采用超声波对大尺寸自密实混凝土和堆石混凝土进行了对比测试,并基于黏弹性介质波动理论从纵波波速测量结果中分离出材料的黏性特征参数,用于分析堆石混凝土的浇筑状态,评价堆石混凝土的施工质量.结果表明:由于堆石混凝土内部结构复杂,仅依靠代表性体积单元的超声波速均值和变异系数难以对堆石混凝土的浇筑质量做出可靠的评价,因而需要进行高密度的分层检测;应用材料的黏性特征参数进行分析判断时,有可能采用较少的测线完成检测,这在工程实践中是更具有应用价值的方法.应用早龄期超声测试的方法有助于克服由于代表性单元尺寸过大给堆石混凝土工程质量评价带来的困难.     

Effect of Cone Angle on the Hydraulic Characteristics of Globe Control Valve

Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle(β). However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient(Cv) when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.     

基于STM32的嵌入式光纤束微位移传感器设计

为了满足当前位移测量系统对于微小位移进行稳定可靠和精确测量的需求,文中提出了一种基于STM32的嵌入式光纤束微位移传感器的设计方案。该光纤束位移传感器主要利用了光强调制型的工作原理,以STM32F103ZET6为核心,采用设计的光纤束微位移传感探头对微位移进行准确测量,软件部分实现了两路检测信号相除、线性化处理和温度补偿等工作,同时将采集的位移数据通过串口实时发送至上位机,实现了对温度数据的动态显示,查询、储存等功能。该传感器具有成本低、测量精度高、操作简单等优点,可以在各种复杂的工业现场高效而准确地对各种微位移进行精确测量。     

自动原理对某型重机枪射击精度的影响研究

针对某型重机枪配用不同枪弹射击精度差异较大的问题,文中首先对该武器的自动原理及其优缺点进行了分析,以建立的某型重机枪枪身系统的动力学仿真模型为平台,对两种自动原理对武器射击频率及枪弹适配性问题进行了仿真研究,并通过与其它同口径机枪的试验结果对比分析,探讨了自动原理对武器动态稳定性的影响情况,为同类武器的结构设计提供参考。     

磷和超稳Y分子筛在深度脱硫过程中增强效应的研究

采用等体积浸渍法分别制备了由磷单独改性、超稳Y分子筛单独改性、以及磷和超稳Y分子筛共同改性的Ni Mo型催化剂。以胜华催化裂化柴油为原料,对催化剂的催化性能进行评价,并采用Py-IR、HRTEM等方法对催化剂进行了表征。结果表明:由磷和超稳Y分子筛共改性的催化剂总酸量、B酸、L酸最多,所形成活性相较多,催化性能最好。从而证实二者在深度脱硫过程中确实存在催化活性上的增强效应。     

Fe_3O_4/羧甲基壳聚糖磁性载药微球的制备及释药性能

通过乳化交联法制备了负载有抗癌药物5-氟尿嘧啶的Fe3O4/羧甲基壳聚糖磁性载药微球。利用红外光谱(IR)和扫描电镜(SEM)对载药微球的结构与形貌进行了表征,研究了影响载药微球载药和释药性能的因素。IR测试显示载药微球中含有磁性Fe3O4;SEM照片显示载药微球尺寸均一,表面光滑。确定制备磁性载药微球的最佳条件为:5-氟尿嘧啶0.5g、磁性Fe3O40.2g、戊二醛8mL;磁性载药微球在温度为35~40℃、pH值为5.2的缓冲溶液中释药量达到峰值,适用于人体十二指肠肿瘤的治疗。     

电火花修锐对金属结合剂CBN砂轮表面形貌的影响

采用电火花修锐方法对青铜结合剂锯齿形CBN砂轮在平面磨床上进行修锐实验,对修锐前后的砂轮表面形貌进行观测,修锐后砂轮的有效磨粒数、磨粒凸出高度明显增加,修锐时间以4~6h为宜;采用修锐后的砂轮对材料2T8/SK5进行了锯齿磨削加工实验,经测量,锯齿角度轮廓精度有较大提高。电火花修锐方法适合于金属基CBN砂轮的修锐。     

Effects of Sr incorporation on surface structure and corrosion resistance of hydroxyapatite coated Mg-4Zn alloy for biomedical applications

Hydroxyapatite (HA) and strontium (Sr) incorporated HA coatings with different Sr contents were prepared on Mg-4Zn substrates by electrochemical deposition method. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electrochemical workstation were applied for the composition, phase constitution, morphology analyses and corrosion tests. The results reveal that the incorporation of Sr in coatings does not lead to dramatical change of functional groups and the crystal structure of the HA phase, but the crystal size and crystallinity decrease with increasing Sr content, which should be attributed to the lattice distortion and different occupancies of Sr and Ca ions. The 10SrHA@Mg-4Zn samples show the lowest corrosion current density and the highest corrosion potential, and also exhibit the lowest amount of hydrogen evolution among all coated samples.