机载预警雷达天线发展趋势及关键技术

综合性预警探测多功能一体化系统是下一代机载预警雷达的一种必然趋势,它要求天线阵面具备多功能、与平台一体化的特征,实现超宽带、多频段性能,并能在硬件资源上支撑数字智能化的系统体系架构。文中首先分析了机载预警雷达天线阵面的发展趋势和国内外研究现状,继而分析了目前机载预警雷达天线系统的关键技术,阐述了相应的技术实施途径和核心问题,提出部分解决方案。     

基于Haar-like和肤色特征的驾驶员脸部检测融合算法

对驾驶员面部疲劳状态进行视觉监测的前提是脸部区域的准确、快速检测。采用改进的基于Haar-like特征的人脸检测算法检测出可能存在的初始人脸区域,然后适当扩大初始人脸区域范围,并在此基础上利用肤色特征和区域连通算法在YCbCr和rgb颜色空间上对人脸区域进行二次定位,最后根据定义的脸部区域重合度和人脸几何特征,实现脸部区域的融合检测。实验结果验证了该算法的准确性和可靠性。     

All‐Fiber Structured Electronic Skin with High Elasticity and Breathability

With the rapid advancement in artificial intelligence, wearable electronic skins have attracted substantial attention. However, the fabrication of such devices with high elasticity and breathability is still a challenge and highly desired. Here, a route to develop an all‐fiber structured electronic skin with a scalable electrospinning fabrication technique is reported. The fabricated electronic skin is demonstrated to exhibit high pressure sensing with a sensitivity of 0.18 V kPa^?1 in the detection range of 0–175 kPa. This wearable device could maintain prominent sensing performance and mechanical stability in the presence of large deformation, even when the elastic deformation is up to 50%. The electronic skin is easily conformable on different desired objects for real‐time spatial mapping and long‐term tactile sensing. Besides, it possesses high gas permeability with a water vapor transmittance rate of 10.26 kg m^?2 d^?1. More importantly, the electronic skin is capable of working in a self‐powered manner and even serves as a reliable power source to effectively drive small electronics. Possessing several compelling features, such as high sensitivity, high elasticity, high breathability as well as being self‐powered and scalable in fabrication, the presented device paves a pathway for smart electronic skins.     

Thermally Controlled,Active Imperceptible Artificial Skin in Visible‐to‐Infrared Range

Cephalopods’ extraordinary ability to hide into any background has inspired researchers to reproduce the intriguing ability to readily camouflage in the infrared (IR) and visible spectrum but this still remains as a conundrum. In this study, a multispectral imperceptible skin that enables human skin to actively blend into the background both in the IR‐visible integrated spectrum only by simple temperature control with a flexible bi‐functional device (active cooling and heating) is developed. The thermochromic layer on the outer surface of the device, which produces various colors based on device surface temperature, expands the cloaking range to the visible spectrum (thus visible‐to‐IR) and ultimately completes day‐and‐night stealth platform simply by controlling device temperature. In addition, the scalable pixelization of the device allows localized control of each autonomous pixel, enabling the artificial skin surface to adapt to the background of the sophisticated pattern with higher resolution and eventually heightening the level of imperceptibility. As this proof‐of‐concept can be directly worn and conceals the human skin in multispectral ranges, the work is expected to contribute to the development of next‐generation soft covert military wearables and perhaps a multispectral cloak that belongs to cephalopods or futuristic camouflage gadgets in the movies.     

CoFe涂层对非晶薄带GMI效应的影响

上制备不同厚度的CoFe薄膜层,观察其巨磁阻抗(GMI)效应在120 kHz~3 MHz频率范围内随外加磁场的变化。实验结果显示,在Co基非晶薄带上涂覆CoFe薄膜,可提高薄带的GMI效应。研究发现,当趋肤效应显著时材料表面粗糙度对GMI效应有较大影响。通过在Co基非晶薄带表面镀膜的方式降低样品表面粗糙度,减小表面退磁场的影响,并闭合样品磁通回路,从而提高样品GMI效应。     

银屑病患者皮损中角蛋白10、14、17及丝聚蛋白表达与分布

目的：研究银屑病患者皮损中角蛋白10、14、17及丝聚蛋白的分布、表达与皮肤屏障功能受损的相关性。方法以20例银屑病患者皮损及10例正常人皮肤为研究对象,运用免疫组化及westerm blot测定两组角蛋白10、14、17及丝聚蛋白的分布与表达。结果：与正常人皮肤相比,银屑病患者的皮损组织中角蛋白10表达和丝聚蛋白表达下调;角蛋白14及17表达上调,但表达程度及部位不同,其差异均具有统计学意义。结论银屑病患者的皮肤屏障功能有受损,可能是银屑病持续发病机制之一。     

一种新的基于直接最小二乘椭圆拟合的肤色检测方法

肤色检测是计算机视觉中的一个重要问题,本文提出了一种新的基于直接最小二乘椭圆拟合的肤色检测方法,其基本思想是根据肤色样本分布区域的边界数据点采用曲线拟合的方法得到肤色分布区域的边界方程。在实现时,为了解决直接在笛卡儿坐标系中提取肤色样本分布区域边界数据的困难,算法采用了一种新的解决思路,即首先把训练肤色样本在色度空间的统计分布转化为图像的形式,然后再利用边缘检测方法得到肤色分布区域的边界数据。根据所得的边界数据点用直接最小二乘椭圆拟合方法便可得到肤色分布区域的椭圆边界,方法简单直观。实践表明,该算法能完成对各种不同环境条件下所拍摄图像的肤色分割,效果理想,其性能明显优于常用的域值界定法和单高斯模型法。     

基于图像内容及底层特征的敏感图像检测方法

内容安全是信息安全领域中的一个新兴且重要的研究方向.敏感图像分析与监控是该方向的一个重要研究分支,近年来愈来愈受到关注.然而,由于其研究起步较晚且图像本身所具有的复杂多样性,相对来说,目前已有的研究成果还比较少且性能上也有待于进一步提升,为此,本文提出了一种新的敏感图像分析检测方法.该方法从基于图像内容分析和基于图像底层特征分析两个方面进行综合分析检测,在基于内容分析方面,通过分析图像是否含有大量的皮肤区域来初步检测敏感图像;在基于图像底层特征分析方面,通过颜色直方图矢量和颜色聚合矢量提取图像的颜色及空间信息,并在此基础上利用SVM进行分类,从而实现敏感图像的初步检测;最后,对上述两方面的初步检测结果进行综合判决,实现敏感图像的最终检测.仿真实验结果出示了该新方法的有效性.     

Double‐Twisted Conductive Smart Threads Comprising a Homogeneously and a Gradient‐Coated Thread for Multidimensional Flexible Pressure‐Sensing Devices

Fiber‐based, flexible pressure‐sensing systems have attracted attention recently due to their promising application as electronic skins. Here, a new kind of flexible pressure‐sensing device based on a polydimethylsiloxane membrane instrumented with double‐twisted smart threads (DTSTs) is reported. DTSTs are made of two conductive threads obtained by coating cotton threads with carbon nanotubes. One thread is coated with a homogeneous thickness of single‐walled carbon nanotubes (SWCNTs) to detect the intensity of an applied load and the other is coated with a graded thickness of SWCNTs to identify the position of the load along the thread. The mechanism and capacity of DTSTs to accurately sense an applied load are systematically analyzed. Results demonstrate that the fabricated 1D, 2D, and 3D sensing devices can be used to predict both the intensity and the position of an applied load. The sensors feature high sensitivity (between ≈0.1% and 1.56% kPa) and tunable resolution, good cycling resilience (>104 cycles), and a short response time (minimum 2.5 Hz). The presented strategy is a viable alternative for the design of simple, low‐cost pressure sensors.