在柠檬酸中制备大孔径阳极氧化铝模板的方法

现有的报道普遍认为柠檬酸作为阳极氧化铝的反应溶液只能制备出致密型的氧化铝膜。笔者发现柠檬酸作为反应溶液在350V直流电压下可制备出孔径600nm左右的多孔型的阳极氧化铝模板(AAO)模板.通过与以往研究结果比较发现要想获得较大孔径的AAO模板需要选择较小电离常数的酸液.在去除阻挡层时,磷酸腐蚀了模板的反面,导致模板反面的孔径大约是正面孔径的一倍.     

大型钢管沉管施工技术分析

沉管法作为管道穿越河流的一种方法,具有适用面宽、不影响通航、施工周期短及工程造价合理等优点,但拼管、吊管、沉管难度大;本文结合某实际沉管工程探讨了大直径（D3 680 mm×40 mm）钢管沉管的施工技术要点,特别对成型管段的平移、管段的水面对接和管道的整体沉放等施工工序进行了详细的论述,为类似工程提供施工经验.     

大电流智能型测量仪表的设计思路

提出了用磁位计作为传感器、配以智能化的电路来完成测量任务的方案,说明了这一方案的电磁原理,设计了智能化测量电路,同时也分析了产生测量误差的各种原因,并给出了相应的解决措施。采用该方案设计而成的电流表,可测量上千安培的交流大电流。     

一种自适应入位固持装置及试验研究

为解决飞机数字化装配中难以对机身大部件增加辅助固持并保持大部件位姿不变的技术难题,提出一种基于气浮和万向球座的大部件位姿跟随固持方法,并设计制造称之为随动定位器的专用柔性工装.结合某工程,进行定位器关键参数的分析计算和相关工艺试验研究,并对油压波动、相关零件磨损对锁紧力的影响以及芯轴自由端关键参数选择与入位可靠性问题进行了研究.结果表明,在芯轴角度偏差较小时,随动定位器可以在确保大部件位姿不被破坏的情况下,实现芯轴的小阻力自适应入位,并可以根据选定的工作油压和配合间隙可靠固持大部件,其性能可以满足工程要求.     

绳系卫星系绳参数的实时估计方法

研究了绳系卫星在轨运动中系绳参数的实时估计方法.分析了现有的估计方法所存在的问题,引入三轴张力计的测量信息和扩展Kalman滤波方法,提出了系绳摆角在大角度变化时系绳参数的实时估计方法,并进行了详细的推导与论证.最后,通过仿真验证了上述估计方案和算法的有效性,且获得了较好的估计精度.     

大口径纹影系统主反射镜装调结构分析与设计

研制纹影测试系统中大口径主球面反射镜的装调结构.利用有限元法,对有效通光口径直径为800 mm的主镜进行应力和面变形分析.采用断裂几率预测法校核玻璃机械强度,通过优化得出反射镜面变形的均方根(rootmean square,RMS),以此为依据,设计出满足系统技术要求的主镜装调结构.     

Modeling large reversible electric-field-induced strain in ferroelectric materials using 90° orientation switching

Reversible large electric-field-induced strain caused by reversible orientation switchings in BaTiO3 is modeled using the Landau's theory of phase transition. A triple well free energy function is constructed. Each of its minima is associated with one of the polarization orientations involved. Nonlinear constitu- tive laws accounting for reversible orientation switchings and electrostriction effects are obtained by using thermodynamic equilibrium conditions. Hysteretic dynamics of one-dimensional structures is described by coupled nonlinear differential equations. Double hysteretic loops in the electric and me- chanic fields are both successfully modeled. Giant reversible electrostriction is modeled as a conse-quence of reversible orientation switchings via electro-mechanical couplings. Comparisons with ex-perimental results reported in literatures are presented.     

光照变化条件下的光流估计

目的 为了提高光流法在处理光照变化和大位移方面的稳健性。提出一种结合结构纹理分解预处理和加权中值滤波的光流场模型。方法 该方法数据项采用灰度守恒假设和梯度守恒假设相结合、局部约束与全局约束相结合的思想。同时采用结构纹理分解、加权中值滤波、金字塔结构等高效的光流估计技术,进一步增强了光流算法的精确性与实用性。结果 分别通过Middlebury光流数据库图像和真实场景图像对提出的光流估计算法进行了大量实验验证。实验结果表明,改进的光流估计法在处理光照变化方面表现不错,不仅获得稠密的光流场,而且提高了光流场准确提取目标边缘的能力。结论 和传统光流方法相比,所提方法在光照变化情况下能获得更加理想的结果,降低了实际场景中光线变化的干扰,能更好地适用于实际场景中。     

HTTP-SoLDiER: An HTTP-flooding attack detection scheme with the large deviation principle

HTTP-flooding attack is a much stealthier distributed denial of service （DDoS） attack, challenging the survivability of the web services seriously. Observing the web access behavior, we find that the surfing preference of normal users is much more consistent with the webpage popularity than that of malicious users. Based on this observation, this paper proposes a novel detection scheme for HTTP-flooding （HTTP-SoLDiER）. Specifically, HTTP-SoLDiER first quantifies the consistency between web users surfing preference and the web- page popularity with large-deviation principle. Then HTTP-SoLDiER distinguishes the malicious users from normal ones according to the large-deviation probability. In practice, the webpage popularity plays a key role in attack detection of HTTP-SoLDiER. Due to the never-ending updating of the webpage content and the disturbance induced by attackers, the webpage popularity often varies over time. Thus, it is critical for HTTP-SoLDiER to dynamically update the webpage popularity. We design a reversible exponentially weighted moving average （EWMA） algorithm to solve the problem. Finally, we evaluate the effectiveness of this scheme in terms of true positive （TF） and false positive （FP） probabilities with NS-3 simulations. The simulation results show that HTTP-SoLDiER can detect all random HTTP-flooding attackers and most of the perfect-knowledge HTTP-flooding attackers at little false positive.     

大型泵站自动化控制系统组成及管理

介绍大型泵站自动化系统的结构及组成,分析其微机自动化管理过程中出现的问题．并提出处理措施及注意事项。