二层交换机的攻击分析与防范技术的研究

本文通过OSI模型的第二层的特点,分析了二层交换机存在的安全隐患,提出了相应的解决办法。     

融合改进 YOLOv7 与 UNet 的编码点定位方法

针对编码点的定位存在误检率高和精准度差的问题,提出了一种融合改进 YOLOv7 与 UNet 的圆形编码点定位方 法。第1阶段使用改进的 YOLOv7 检测编码点的位置,改进的 YOLOv7 首先将DCN-v2 可变形卷积引入 ELAN 模块,提升 特征提取能力;其次把卷积块注意力模块(CBAM) 机制嵌入骨干网络使网络更关注目标特征;然后使用Focal-EloU Loss 提高 收敛速度;最后构建 OD-Cat 模块替换 ConCat 模块以提升网络检测精度。提取出每个圆形编码点的 ROI 后,第2阶段通过 UNet 分割出编码点的中心轮廓后,使用最小二乘法拟合出编码点的中心。实验结果表明,改进后的模型比原 YOLOv7 的精 确率提高了6.33%,平均精度均值(mAP) 提升了5.76%;提出的定位方法验证了在噪声、亮度不足或曝光等复杂环境下可以 准确定位出编码点的中心椭圆轮廓,在实际工业视觉测量中具备鲁棒性。     

Hydrogen plasma treatment of very thin p-type nanocrystalline Si films grown by RF-PECVD in the presence of B(CH3)3

Abstract

We have characterized the structure and electrical properties of p-type nanocrystalline silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition and explored optimization methods of such layers for potential applications in thin-film solar cells. Particular attention was paid to the characterization of very thin (～20 nm) films. The cross-sectional morphology of the layers was studied by fitting the ellipsometry spectra using a multilayer model. The results suggest that the crystallization process in a high-pressure growth regime is mostly realized through a subsurface mechanism in the absence of the incubation layer at the substrate-film interface. Hydrogen plasma treatment of a 22-nm-thick film improved its electrical properties (conductivity increased more than ten times) owing to hydrogen insertion and Si structure rearrangements throughout the entire thickness of the film.     

Atomic layer deposition of thin films of ZnSe—structural and optical characterization

Thin films of sphalerite-type ZnSe were grown by atomic layer deposition (ALD) from elemental Zn and Se precursors. These films, grown on various substrates, show bright blue ‘edge’ emission accompanied by donor-acceptor pair emissions in the blue, green and red spectral regions. Red, green and blue emissions mixed together give a white color, with a color temperature between 2400 and 4500 K depending on a layer thickness and temperature. ZnSe grown by ALD is in consequence a promising material for the fabrication of semiconductor-based white light emitting thin film electroluminescence displays.     

Neutrophils Mediate Pulmonary Artery Thrombosis In Situ

Pulmonary embolism is a life-threatening condition, which can result in respiratory insufficiency and death. Blood clots occluding branches of the pulmonary artery (PA) are traditionally considered to originate from thrombi in deep veins (usually in legs). However, growing evidence suggests that occlusion of the vessels in the lungs can develop without preceding deep vein thrombosis (DVT). In this work, we used an inferior vena cava (IVC) complete ligation model of DVT in Wistar rats to explore the possibility and mechanisms of PA thrombosis under the conditions where all routes of thrombotic mass migration from peripheral veins are blocked. We demonstrate that rats both with normal and reduced neutrophil counts developed thrombi in the IVC, although, neutropenia caused a substantial decrease in thrombus size and a shift from fresh fibrin toward mature fibrin and connective tissue inside the thrombus. Massive fibrin deposition was found in the PA branches in the majority of DVT rats with normal neutrophil counts, but in none of the neutropenic animals. Neutrophil ablation also abolished macroscopic signs of lung damage. Altogether, the results demonstrate that thrombi in the lung vasculature can form in situ by mechanisms that require local neutrophil recruitment taking place in the DVT setting.     

中厚板矫直过程中中性层偏移动态研究

研究中性层偏移对矫直力的影响,以提高矫直力精度。通过对矫直件三维弹塑性变形进行分析,提出中性层偏移理论,利用数值模拟和实验讨论中性层偏移的动态变化规律,说明中性层偏移是影响矫直力精度的重要因素之一,并验证了理论推导公式与数值计算结果之间的误差,为建立更为准确的矫直力模型提供理论基础和数据。     

30.4 nm Si/C多层膜反射镜的制备与测量

采用离子束溅射镀膜装置制备了一种新的材料组合Si/C多层膜 ,用于 30 4nm波段的正入射多层膜反射镜。并用软X射线反射率计测得其反射比最大值为 0 14。有效地抑制了 15 0nm处的二级衍射峰。     

Growth of calcium carbonate by the atomic layer chemical vapour deposition technique

Thin films of CaCO₃ (calcite) have been grown with the atomic layer chemical vapour deposition (ALCVD) technique, using Ca(thd)₂ (Hthd=2,2,6,6-tetramethylheptan-3,5-dione), CO₂, and ozone as precursors. Pulse parameters for the ALCVD-type growth are found and self-limiting reaction conditions are established between 200 and 400 °C. Calcium carbonate films have been deposited on soda-lime glass, Si(100), -Al₂O₃(001), -Al₂O₃(012), -SiO₂(001), and MgO(100) substrates. The observed textures were: in-plane oriented films with [100](001)CaCO₃ [100](001)Al₂O₃ and [100](001)CaCO₃[110](001)Al₂O₃ on -Al₂O₃(001), amorphous films on -Al₂O₃(012) when grown at 250 °C, and columnar oriented films on soda-lime glass, Si(001), -SiO₂(001), and MgO(100) substrates with (00l) and (104) parallel to the substrate plane at 250 and 350 °C, respectively. The film topography was studied by atomic force microscopy and AC impedance characteristics were measured on as-deposited films at room temperature. The films were found to be insulating with a dielectric constant (_r) typically approximately 8. Thin films of CaO were obtained by heat treatment of the carbonate films at 670 °C in a CO₂-free atmosphere, but the thermal decomposition led to a significant increase in surface roughness.     

Effect of Seed Layer on the Orientation of Zinc Oxide Film on Silicon Substrate

1. IntroductionZinc oxide films have been attracting more and moreattention because of their high diffractive index, low resis-tance, and photoluminescence properties, and are beingused as transparent electrodes, basis material for opti-cal wave guide devices, gas sensors and so on. Manymethods have been developed to prepare ZnO films, suchas chemical vapor deposition[1], reactive evaporation[2],pulsed laser ablation[3], sputtering[4], spray pyrolysis[5]and hydrothermal method[6]. There are a…     

综合航电开放式软件设计技术

综合航电开放式软件设计技术是新一代航电系统支持平台机载实时容错分布式计算机系统的重点,它的设计直接或间接地关系到新一代综合航电系统的性能和成本.针对先进综合航电系统的特点、性能要求,对目前机载计算机软件系统存在的可靠性、安全性低,不易移植,成本高,层次分割不清晰,功能独立性差,对系统容错支持能力弱等缺陷,提出了"三层栈结构"的软件设计新思想,通过标准接口(物理接口和逻辑接口)使得层与层,模块与模块之间得以分开,实现了功能模块化、软硬件隔离性、软件的再利用性、可剪裁性、易维护性,以适应不断增长的航空电子系统任务能力需求,为新一代航电系统支持平台机载实时容错分布式计算机系统的开发、研制提供了可靠的保证.