面向公众的道路交通综合信息服务平台研究

目前,公众对道路交通信息需求日益强烈,希望主管部门提供更多的交通资源运行状况信息实时发布.本文主要描述了以整合现有的交通信息资源为基础,利用视频监控、GIS技术,以"信息采集、信息处理、信息展示、信息提醒"为基本架构,构建面向公众的道路交通综合信息服务平台.     

A high sensitive 66 dB linear dynamic range receiver for 3-D laser radar

This study presents a CMOS receiver chip realized in 0.18 μm standard CMOS technology and intended for high precision 3-D laser radar. The chip includes an adjustable gain transimpedance pre-amplifier, a post-amplifier and two timing comparators. An additional feedback is employed in the regulated cascode transimpedance amplifier to decrease the input impedance, and a variable gain transimpedance amplifier controlled by digital switches and analog multiplexer is utilized to realize four gain modes, extending the input dynamic range. The measurement shows that the highest transimpedance of the channel is 50 kΩ, the uncompensated walk error is 1.44 ns in a wide linear dynamic range of 66 dB (1:2000), and the input referred noise current is 2.3 pA/√Hz (rms), resulting in a very low detectable input current of 1 μ A with SNR=5.     

对称非线性包层平板多量子阱波导TE模的传播特性

分别用精确计算和方均根近似方法得到了包层及衬底均为非线性Ｋｅｒｒ型介质、芯区为多量子阱的对称平板波导中ＴＥ模的传播特性。数值计算表明,当芯区多量子阱的层数较多时,方均根近似方法得到的结果与用精确方法得到的结果一致,此时多量子阱波导可以等效为均匀介质。对于自聚焦情况,在合适的光功率下,当分界面处包层（及衬底）的有效折射率与芯区折射率相等时,芯区的场分布呈均匀分布而两侧的场呈指数式衰减;功率继续增大时,场分布的极值进入芯区两侧,而芯区场分布呈下凹形。对于自散焦情况,波导对导波场有较强干线性波导的束缚作用,且随光功率的增大而增强。     

High‐Strength Laminated Copper Matrix Nanocomposites Developed from a Single‐Walled Carbon Nanotube Film with Continuous Reticulate Architecture

A critical challenge in nanocomposite fabrication by adding SWCNTs as reinforcement is to realize an effective transfer of the excellent mechanical properties of the SWCNTs to the macroscale mechanical properties of the matrix. Using directly grown SWCNT films with continuous reticulate structure as the template, Cu/SWCNTs/Cu laminated nanocomposites are fabricated by an electrodepositing process. The resulting Cu/SWCNTs/Cu laminated nanocomposites exhibit extremely high strength and Young's modulus. The estimated Young's modulus of the SWCNT bundles in the composite are between 860 and 960 GPa. Such a high strength and an effective load‐transfer capacity are ascribed to the unique continuous reticulate architecture of SWCNT films and the strong interfacial strength between the SWCNTs and Cu matrix. Raman spectroscopy is used to characterize the loading status of the SWCNTs in the strained composite. It provides a route to investigate the load transfer of SWCNTs in the metal matrix composites.     

基于支持向量机算法的多环芳烃表面增强拉曼光谱的定量分析

以硫氰化钾(KSCN)为内标物,利用主成分分析(PCA)降维,利用支持向量机(SVM)算法建立定量分析模型——支持向量回归(SVR),并结合网格搜索(GS)、遗传算法(GA)和粒子群优化算法(PSO)三种参数优化方法,实现了芘、菲单一溶液和混合溶液的定量分析。研究结果表明:以KSCN为内标物,提高了定量分析结果的准确性;利用PCA降维提高了建模速度;三种优化模型对芘预测的平均相对误差(ARE)在7.6%以内,对菲预测的ARE在11.3%以内;三种参数优化方法对同一物质的预测结果相近,但GS的运算速度最快;综合考虑误差和分析速度后,采用GS-SVR模型获得了菲、芘混合溶液的最佳结果。表面增强拉曼光谱(SERS)技术结合SVM算法有望实现多环芳烃的定量分析。     

基于改进RGB-N的图像操纵检测算法

如何准确地检测出图像中的操纵痕迹是数字图像被动取证领域的研究重点.传统方法利用人工构造的特征进行检测,鲁棒性不强,而基于深度学习的方法虽具有较强的检测能力,但较少关注在正常图像上出现误检的情况.提出了一种改进的RGB-N图像操纵检测算法,该算法在使用F1分数评价操纵目标检测性能的同时,引入了在正常图像上的误检率指标来评价算法的实用性.设计了自适应空域富模型滤波器,构造多尺度融合的特征提取网络,并接入自注意力模块,增强了模型获取图像全局信息的能力,提高检测性能;为降低误检率,设计了真实性判断模块,输出的热图用于判断检测到的目标是否为误检,并通过从操纵目标来源图像选择负样本的训练策略进一步提高模型的分辨能力.实验结果表明,改进的RGB-N模型在含目标拼接与擦除两种操纵手段的数据集上的F1分数为0.759,在未操纵图像数据集上的误检率为0.2％,并在JPEG压缩攻击下具有较好的鲁棒性.     

半导体激光器单管准直实验研究

利用高斯光束的ABCD传输矩阵理论分析了LD与自聚焦透镜之间的距离与出射光束远场光斑尺寸之间的关系.通过理论计算可以方便地得到最佳距离,获得较高亮度输出,并进行了实验验证.对平面自聚焦透镜、球面自聚焦透镜和圆柱透镜的准直效果进行了实验比较,最后将自聚焦透镜与LD固定,制做了实用的器件,该器件可以将LD椭圆形光斑转变成线形光斑,快轴、慢轴远场发散角分别为0.1°和2.50°耦合效率86%.     

无热阵列波导光栅的新颖制作方法

提出了一种制作无热AWG的新颖方法,采用了专利设计的ITU-T中心波长调节装置、简单的方法来耦合被切开两部分、以及毛细渗透的点胶方式。波长调节精度达到1pm。这种无热实现方案没有带来任何光谱恶化,其光谱几乎同原始芯片一样。这种40通道100GHz通道间隔平顶型无热AWG,在-40 to 85℃范围内,中心波长漂移±22pm,插损变化小于±0.11dB。     

Neurotoxicity of Chronic Co-Exposure of Lead and Ionic Liquid in Common Carp: Synergistic or Antagonistic?

Previous studies have indicated that the harmful heavy metal lead (Pb) contamination in aquatic systems has caused intelligence development disorders and nervous system function abnormalities in juveniles due to the increased permeability of the blood–brain barrier. Ionic liquids (ILs) are considered “green” organic solvents that can replace traditional organic solvents. Studies have found the presence of ILs in soil and water due to chemical applications or unintentional leakage. Therefore, what would happen if Pb interacted with ILs in a body of water? Could ILs enable Pb to more easily cross the blood–brain barrier? Therefore, we examined the combined exposure of Pb and ILs in common carp at low concentration (18.3 mg L⁻¹ of Pb(CH₃COO)₂•3 H₂O and 11 mg L⁻¹ of the IL 1-methyl-3-octylimidazolium chloride, 5% of their LC₅₀) for 28 days in the present study. The result of a neurobehavioral assay showed that chronic exposure of lead at lower concentrations significantly altered fish movement and neurobehaviors, indicating that lead exposure caused neurotoxicity in the carp. Increases in the neurotransmitter dopamine levels and injuries in the fish brain accounted for neurobehavioral abnormalities induced by lead exposure. Moreover, we also found that lead could easily cross the blood–brain barrier and caused significant bioaccumulation in the brain. Particularly, our study indicated that the ionic liquid could not synergistically promote blood–brain barrier permeability and hence failed to increase the absorption of lead in the fish brain, suggesting that the combined exposure of lead and ILs was not a synergistic effect but antagonism to the neurotoxicity. The results of this study suggested that ILs could recede the Pb induced neurotoxicity in fish.