一种基于危险信号的拒绝服务入侵检测方法

针对拒绝服务(Denial of Service,DoS)攻击的特点,提出了一种基于免疫危险理论的新型入侵检测方法,设计、实现了检测算法和抗体变异、进化算法。引入血亲类方法分类抗原/抗体,定义了抗原凋亡和坏死的过程,定量计算抗原危险信号和网络危险度,并以此检测DoS攻击。仿真实验表明该方法不仅具有基于传统人工免疫理论的入侵检测自学习、自适应的优点,而且误警率降低87.5%,检测效率更高。     

P2P网络中基于RDF/S的数据库语义查询系统设计*

提出一种P2P网络环境下基于RDF/S 数据模型的数据库语义查询原型系统,可以有效地对各种基于ODBC的异构数据源进行语义查询。首先数据内容经RDF/S描述成RDF/S schema片断形式,然后对片段进行编码,再把编码杂凑到DHT中,就可以使用Chord协议定位目标节点。     

导磁体在汽车零件感应加热中的应用技术

本文简单介绍了导磁体工作的基本原理，并给出在汽车零件大规模生产中所积累的导磁体应用的一些经验，以阐明如何更有效地使用导磁体。     

螺旋埋弧焊管全管体扩径工艺与性能研究

随着管道建设对管材性能一致性要求的提高,以及全位置自动焊工艺对管材几何尺寸精度更高的要求,需要研究改进螺旋焊管制备工艺。开展了X80钢级Φ1 219 mm×22 mm螺旋埋弧焊管全管体扩径工艺试验,对比分析了扩径前后管体的几何尺寸、残余应力及力学性能变化。结果显示,随着扩径量的增加,管体尺寸精度大幅提高,在扩径率为0.75%时,管体不圆度降低了20%,周长一致性提高了71%,噘嘴量减少35.4%,管体切断后对应的两个管端直径差值在1 mm之内;扩径可以进一步降低管材成型焊接形成的整体内应力以及表面应力,使得螺旋埋弧焊管残余应力一定程度减小;扩径后管材强度和屈强比略有上升,韧性略有下降,管材强度的一致性大幅提高,管材相关性能指标优于设计及施工标准要求。结果表明,X80钢级Φ1 219 mm×22 mm螺旋埋弧焊管扩径工艺技术是可行的。     

浮式风电装备动态响应敏感性参数分析

为研究各参数对浮式风电装备动态响应的影响程度,寻找响应变化规律和设计优化方向,根据海装6.2 MW浮式风电装备参数进行一体化仿真。结合规范要求、设计经验和环境条件特点,针对不同环境条件的重现期、风谱类型、波浪谱类型、极端阵风周期进行参数敏感性分析,得到浮式风电装备不同部分动态响应结果。结果表明：不同环境条件的重现期和组合方式对运动响应和锚链张力影响十分明显,对机组载荷的影响则与机组所处状态相关;风谱类型主要影响机组载荷,对平台运动和锚链张力影响不大,考虑空间相干性的湍流风谱结果最危险;波浪谱类型对运动幅值和锚链张力极值影响较大,在发电工况下对机组载荷的影响较小,但在空转工况下对机组载荷的影响较大;阵风周期对运动响应、塔筒载荷、机舱加速度影响相对明显,但对轮毂载荷、锚链张力影响不大。     

凝胶法制备Cu-BTC块体及其吸附脱除二甲基二硫醚性能

金属有机骨架材料Cu-BTC具有高孔隙率、易调控的骨架结构以及含过渡金属等特点,是吸附脱除硫化物的优异材料。采用凝胶法在常温条件下制备块状样品Cu-BTC-g,并通过X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(FT-IR)、拉曼光谱(Raman)、X射线光电子能谱(XPS)、N₂吸附-脱附等手段对其进行分析表征,同时测定Cu-BTC-g样品对模型硫化物二甲基二硫醚(DMDS)的静态吸附容量、吸附热力学和动力学特性。结果表明：凝胶法制备的Cu-BTC-g样品晶体平均尺寸约为0.2μm、比表面积为901 m²/g、孔体积为0.40 cm³/g,晶体尺寸、比表面积和孔体积均小于溶剂热法合成的样品Cu-BTC-s;在吸附温度298 K下,Cu-BTC-g样品的DMDS吸附容量为110.8 mg/g,比Cu-BTC-s样品提高12%。     

海上油田多元热流体吞吐气窜调剖实验研究及应用北大核心CSCD

目的多元热流体吞吐技术是海上稠油开发的一种经济、有效的技术,但随着吞吐轮次的增加,暴露出易发生“气窜”的问题,即N_(2)、CO_(2)等非凝析气体容易突破到周边生产井,导致其电泵气锁关井影响生产。方法以渤海NB稠油油田为研究对象,采用可视化实验方法,研究防止气窜的治理策略。结果筛选出适合油田的磺酸基泡沫调堵体系,命名为QGQ-4,优化研究出最佳注入参数为质量分数0.4%、泡沫干度在60%以上、地面预制泡沫注入方式。与单纯多元热流体驱相比,泡沫辅助多元热流体驱可提高油藏波及,有效封堵气窜通道,提高平面波及系数37%。结论研究成果现场应用后,受益井初期高峰日产油增加到措施前的1.5倍,日产油由措施前的50.5 m^(3)增至措施后的高峰日产油75.7 m^(3),取得了较好的增产效果。     

High efficient separation of olefin from fluid catalytic cracking naphtha: Separation mechanism and universal simulation method

The fluid catalytic cracking (FCC) naphtha critical component-oriented separation process is an efficient method to produce ultra-low-sulfur (<10 μg/g) gasoline with minimal loss of octane number (<1 RON). However, the product quality is highly dependent on the structure of the components of FCC naphtha. Aromatics and thiophene sulfides without a methyl side chain favor the separation of olefin. The major impulse of olefin separation is the solvent-induced dipole of aromatics or thiophene sulfides, leading to a “Plane-to-Plane” combination between the solvent and aromatics or thiophene sulfides, accompanied by a steric hindrance due to their side chains. This condition resulted in 2–3 times greater θ of benzene and thiophene compared with that of toluene and 3-methylthiophene. In addition, an improved non-random two-liquid model was proposed based on the above results, and a simulation method for FCC naphtha solvent extraction process was established. The calculation results accorded well with industry data.     

Systematic study of structure and piezoelectric properties of Pb(Ni1/3Nb2/3)O3-PbTiO3 by in situ synchrotron diffraction

Lead-based ferroelectric materials are extensively employed in industrial applications and everyday life due to their excellent ferroelectric and piezoelectric performance. Pb(Ni_1/3Nb_2/3)O₃-PbTiO₃ (PNN-PT) is a typical binary relaxor ferroelectric system, whose refined structure and piezoelectric properties have not been systematically investigated. In this study, evolution of electric field-based crystal structure and variation of ferroelectric, piezoelectric, as well as dielectric properties with composition and temperature of (1 − x)PNN-xPT (0.32 ≤ x ≤ 0.36) ceramics were studied in full detail. The optimal performance is obtained at 0.66PNN-0.34PT with maximum piezoelectric coefficient d₃₃ of 560 pC/N and large dielectric constant of 28 684. In situ high-energy synchrotron diffraction was employed to determine structural origins of enhanced properties of 0.66PNN-0.34PT. Interestingly, crystal structure of poled 0.66PNN-0.34PT ceramic is determined to be single monoclinic phase. Furthermore, both its lattice parameters and volume variation present butterfly shape under electric field. It is demonstrated that macroscopic strain of 0.66PNN-0.34PT stems mainly from intrinsic structure. The present study provides evidence for the relationship between microstructure and macroscopic properties, which is beneficial to the design of new materials with piezoelectric properties.