Radar Testing of the Relative Velocity of Light in Space

Published interplanetary radar do to presents evidence that the relative velocity of light in space is c+v and not c.     

Design and Validation of Rugged Microwave Photonic Network for Phased-Array Radar

Abstract

Military radar has the requirement of 24 × 7 operation in harsh environments with a high level of safety and integrity built in for equipment and personnel working with it. This article presents an application of a microwave photonic network for phased-array military radar. The design challenge is to realize faithful reproduction of the input microwave signals over extreme temperature and frequency ranges. Environmental testing has been carried out to validate the performance of the proposed microwave photonic network over 2–4 GHz and a temperature range of –20°C to +55°C. The result shows that the photonic network can be successfully utilized for phased-array radar.     

Detection of Target Embedded in Sea Clutter by Means of Millimeter Wave Radar

Sea clutter was measured using a millimeter wave radar with a frequency of 34.86GHz and pulse length of 30ns. A car carrier ship target was embedded in sea clutter. It has been discovered that target pulse-to-pulse fluctuations obey a Weibull distribution and sea clutter obey a Rayleigh distribution. We obtained target to clutter ratio improvement of 23.8dB by applying the cell average LOG/CFAR techniques. The computer simulation has been made to evaluate the detection probability and the false alarm probability. The simulation result was in good agreement with the observed data.     

超导滤波器、超导卫星接收机和超导气象雷达的研究进展

近年来，国际上高温超导微波器件的应用取得了重大突破，国内的高温超导微波应用也取得了重要进展．文章回顾了中国科学院物理研究所在探索具有高性能的高温超导滤波器以及同一芯片上不同类型超导滤波器的集成等方面的一些进展，其中部分滤波器分别在相对带宽（优于0．25％）、返回损耗（优于-22．5dB）、带边陡度（例如大于140dB／MHz）、指定频段的抑制（超过110dB）等方面显示了优异的性能．对于在国内进行的首次高温超导滤波器空间环境模拟试验、首次使用高温超导滤波器子系统的卫星接收机前端地面试验和首次使用高温超导微波子系统的气象雷达的现场试验，文章也做了介绍．     

Sea Clutter Suppression and Target Detection Algorithm of Marine Radar Image Sequence Based on Spatio-Temporal Domain Joint Filtering

In marine radar target detection, sea clutter will cause a large number of missed alarms and false alarms, which will affect the accuracy of target detection. In order to suppress sea clutter effectively, a sea clutter suppression and target detection algorithm of marine radar image sequence based on spatio-temporal domain joint filtering is proposed in this paper. The proposed method is to add a sea clutter suppression link before detecting the target. Firstly, the marine radar image sequence is transformed into three-dimensional frequency wavenumber domain by three-dimensional fast Fourier transform (3D-FFT), and then the three-dimensional image spectrum is obtained. According to the fact that the sea clutter spectrum obtained from the image spectrum satisfies the dispersion relation of linear wave theory in the three-dimensional frequency wavenumber domain, a sea clutter model is established. Then, through the established sea clutter model, a spatio-temporal domain joint sea clutter suppressor is designed to filter the image spectrum. After that, the filtered image spectrum is transformed by three-dimensional inverse fast Fourier transform (3D-IFFT) to obtain the image sequence in which sea clutter is suppressed. Finally, target detection is carried out for sea clutter suppressed image sequence. The method is validated by using the real data of X-band marine radar. Compared with the classical Empirical mode decomposition (EMD) method, the improvement of signal-to-noise ratio (SNR) is more obvious, and SNR can be increased by 15.3 db at most. In addition, compared with target detection on original images directly, the proposed method has excellent detection rate and can increase detection rates by at least 8%.     

太赫兹时域光谱技术及激光雷达光谱探测误差分析与实验验证

太赫兹波是指频率介于0.1～10 THz之间的电磁辐射,在电磁波谱上位于微波和远红外光之间。大多数生物战剂爆炸物在此波段有特征吸收。与在公共安全领域检测武器、生物战剂等危险品的传统方法相比,太赫兹辐射能量低,不会产生电离辐射,对物质可以做到高灵敏、无损伤和远距离检测。介绍了国内外太赫兹时域光谱技术在在生物战剂爆炸物检测方面的研究最新进展,并设计了一种激光雷达光谱探测与实时测量装置,以傅里叶光学与光信号处理为基础,使用楔形标准具作为分光镜,实现背景噪声去除、激光探测和光谱测量。测试结果表明,可探测激光雷达脉冲宽度为10 ns,并初步探讨了影响实验结果的几种因素,提出将激光雷达光谱探测技术与太赫兹时域光谱技术相结合,并采用现代模式识别、信号处理技术是生物化学战剂爆炸物实时光谱检测技术的发展趋势。     

Einstein,de Sitter and the beginning of relativistic cosmology in 1917

In 1917, both Einstein and de Sitter proposed a new interpretation of the universe as a whole: the structure of the universe could be described in terms of relativistic field equations. Their contributions marked the beginning of the modern scientific comprehension of the origin and evolution of the universe. Our aim is to propose a critical review paper, based on references in primary sources, on the formulation in 1917 of Einstein’s and de Sitter’s models of the universe, which represents a fundamental chapter in the history of relativistic Cosmology.     

太赫兹技术用于关节软骨检测的研究进展

骨关节炎是主要由软骨组织损伤与退化引起的常见关节疾病,是影响人类健康的重大疾病之一,对于关节软骨组织早期病变的检测可以大大提高疾病的治愈率,然而相关的临床诊断技术尚未发现。近年来,太赫兹技术在医学领域日益受到关注。与传统方法相比,太赫兹辐射能量低,不会产生电离辐射,可高灵敏、无损伤地对生物组织进行成像检测,因此在关节软骨诊断方面具有较大的应用潜力。本文简要介绍了关节软骨的生理与病理情况以及目前关节软骨检测的主要方法,重点总结了太赫兹技术应用于关节软骨检测方面的相关研究工作,分别包括对动物与人类关节软骨的检测,探讨了太赫兹技术在关节软骨检测中所面临的挑战与未来研究展望。     

拉曼光谱技术在病原微生物检测中的应用

病原微生物是指可侵犯人体,引起感染的微生物,临床上由病原微生物感染引发的疾病极为常见。传统的临床病原菌诊断主要依赖于细菌培养,但此方法耗时长,往往需要2～5 d才能得到检测结果,并且存在部分细菌培养困难甚至无法培养的问题。在无法鉴别菌种以及药物敏感性的情况下医生凭借经验使用广谱抗生素,加速了细菌耐药性的产生。因此,病原微生物的高灵敏快速检测方法研究成为重要研究方向。拉曼光谱技术是一种对待测样品进行原位、非侵入性检测的技术,可在单细胞水平上提供微生物细胞中不同生物分子的指纹图谱信息,通过这些信息可以确定微生物的种类、生理特征和突变表型等,实现对微生物样品的快速检测。随着激光光谱学的快速发展以及临床需求的不断增加,促使了以拉曼光谱检测技术为核心的亚技术诞生（如：表面增强拉曼光谱技术、傅里叶变换拉曼光谱技术、激光共振拉曼光谱技术、共聚焦显微拉曼光谱技术、相干反斯托克斯拉曼光谱以及受激拉曼光谱等相关技术）,同时改善了以往拉曼光谱技术信号强度弱的不足,以实现对微生物高精度的快速检测分析。凭借着其具有对样本的状态没有限制以及能够检测物质成分微小变化的优势,近年来对拉曼光谱在病原微生物领域的研究日渐增多。对微生物检测的研究现状进行了调查和分析,围绕着拉曼光谱技术原理对其在微生物检测中的应用进行了具体阐述,其中主要对该技术在病原微生物鉴定以及药敏检测中的研究进展展开讨论,并就其与传统检测技术之间的差别和优势进行分析,展示了拉曼光谱技术作为病原微生物的快速检测新方法的前景。     

A note on conserved charges of asymptotically flat and anti-de Sitter spaces in arbitrary dimensions

The calculation of conserved charges of black holes is a rich problem, for which many methods are known. Until recently, there was some controversy on the proper definition of conserved charges in asymptotically anti-de Sitter (AdS) spaces in arbitrary dimensions. This paper provides a systematic and explicit Hamiltonian derivation of the energy and the angular momenta of both asymptotically flat and asymptotically AdS spacetimes in any dimension D  ≥  4. This requires as a first step a precise determination of the asymptotic conditions of the metric and of its conjugate momentum. These conditions happen to be achieved in ellipsoidal coordinates adapted to the rotating solutions. The asymptotic symmetry algebra is found to be isomorphic either to the Poincaré algebra or to the so(D − 1,2) algebra, as expected. In the asymptotically flat case, the boundary conditions involve a generalization of the parity conditions, introduced by Regge and Teitelboim, which are necessary to make the angular momenta finite. The charges are explicitly computed for Kerr and Kerr–AdS black holes for arbitrary D and they are shown to be in agreement with thermodynamical arguments. The author is a FRIA-FNRS bursar (National Fund for Scientific Research, Belgium).     

中国原子光谱技术及应用发展近况

原子光谱（atomic spectrometry,AS）技术作为分析领域一个重要的组成部分,是尖端科学快速发展的助推器。随着国家对高新技术的愈加重视,国内的分析检测技术也在飞速发展,原子光谱技术作的发展则成为了极其重要的推动力。对中国原子光谱近4年（2015年-2018年）的研究成果与应用进展做了一个综述,内容主要分为六大部分：原子发射光谱（atomic emission spectrometry, AES）包括电感耦合等离子体发射光谱（inductively coupled plasma optical emission spectrometry, ICP-OES）,辉光放电发射光谱（glow discharge optical emission spectrometry, GD-OES）,介质阻挡放电发射光谱（dielectric barrier discharge optical emission spectrometry, DBD-OES）和激光诱导击穿光谱（laser induced breakdown spectrometry, LIBS）;原子吸收光谱（atomic absorption spectrometry, AAS）包括火焰原子化吸收光谱（flame atomic absorption spectrometry, FAAS）,石墨炉原子化吸收光谱（graphite furnace atomic absorption spectrometry, GFAAS）和氢化物发生原子吸收光谱（hydride generation atomic absorption spectrometry, HGAAS）;原子荧光光谱（atomic fluorescence spectrometry, AFS）;X射线荧光光谱（X-ray fluorescence spectrometry, XRF）;元素质谱（elemental mass spectrometry, EMS）包括电感耦合等离子体质谱（inductively coupled plasma mass spectrometry, ICP-MS）,辉光放电质谱（glow discharge mass spectrometry, GDMS）,激光电离源质谱（laser ionization mass spectrometry, LIMS）和原子探针层析成像（atom probe tomography, APT）;原子光谱分析的联用技术。主要关注了各个技术及各种联用技术在仪器设备、检测方法、检测性能上的突破和创新,并简要介绍它们在电子、冶金、地质、环境、制药、食品、生命科学等多种领域中的应用。     

逐线积分气体吸收模型及其在NDIR气体检测中的应用

介绍了一种精确的逐线积分痕量气体吸收模型,模型适用于中红外波段大气环境中痕量气体、污染气体检测的理论研究和工程应用。首先介绍了气体辐射特性的理论计算方法和现有逐线积分大气模 型,比较了各自的优劣性,其次详述了逐线积分计算的理论: 吸收系数是温度、波长、气体浓度和相关吸收线参数的函数,单条谱线的平均吸收系数是积分线强与谱线线型的卷积,在不同的大气条件下选 择不同的线型。最后,详细描述了模型的算法细节,并给出了模型计算的结果与傅里叶变换光谱仪实测数据的对比,举例介绍了吸收模型在NDIR气体探测技术中的实际应用,并使用该模型模拟了NDIR探 测器两个通道的信号强度随尾气中CO₂,CO浓度变化的关系,通过计算确定了NDIR探测器合适的工作范围。所述模型利用HITRAN光谱数据库,考虑了展宽、线翼截断、温度修正、光谱分辨 率变化等情况,可以有效的模拟大气环境中多种气体的红外吸收特征。     

Detection and Location of Multi-Period Phenomena in Chaotic Binary Sequences

Due to the influence of finite calculation accuracy and binary quantization method, the performance of chaotic binary sequences has been degraded in varying degrees, and some sequences emerge as multi-period phenomena. Aiming at the problem that it is difficult to accurately detect this phenomenon, this paper proposes a multi-period positioning algorithm (MPPA), which can accurately detect and locate the accurate period and local period phenomena contained in chaotic binary sequences. In order to test the effectiveness and correctness of the algorithm, the multi-period characteristics of logistic binary sequences with different calculation accuracy are analyzed. MPPA evaluates the randomness of binary sequences from a new perspective, which provides a new idea for the analysis of cryptographic security of chaotic sequences.     

舰炮武器系统光电传感器与雷达数据融合及应用

目标参数的质量直接影响武器系统的命中概率,因此,光电、雷达传感器数据的选优尤为重要,数据融合解决了这一问题。针对舰炮武器系统雷达及光电传感器的数据融合,建立了数学模型,并根据所建立的模型提出工程实践,提高了武器系统的命中率。     

X射线光谱技术在生物与生态环境中的应用进展

环境样品中元素的浓度、空间分布和赋存形态等是认识元素的生物功能和环境行为的关键。本文对近年来X射线光谱技术在生物与生态环境中的应用研究进展进行了评述,发现X射线荧光光谱技术可以提供活体植物中元素迁移与分布的定量数据,且微区X射线荧光光谱和X射线吸收谱技术的联用可深入认识生物与元素的相互作用,尤其是生物对元素的吸收、转运、贮存和细胞解毒机制,同时也能够揭示典型环境样品中元素的来源、演化和归趋等环境行为。然而,由于生物和环境样品基质的复杂性和多样性,仍存在一些技术难点与挑战,如X射线荧光自吸收效应的克服、低丰度(5%～10%)的元素形态的准确鉴定,以及对活体细胞中短暂的元素氧化还原反应的捕捉等。     

某型相控阵雷达信号处理系统故障诊断系统设计与应用

针对某型相控阵雷达信号处理分系统故障部位难以定位,严重影响雷达工作能力这一难题,本文通过对故障现象进行分类,建立相应的故障匹配文件库,采用精确单模式串匹配算法,设计开发了一套故障诊断软件。该软件实现了故障部位准确定位功能,为快速、及时排除故障提供了技术支持,并在实际应用中验证了其正确性。     

基于特征线理论的辨识法在激波装配中的应用

准确地给出激波位置信息对于激波装配极为重要.但是,在使用计算流体力学（computational fluid dyna-mics,CFD）方法模拟复杂流动时很难准确地给出激波的位置.根据激波捕捉得到的流场信息确定的激波位置往往带有极大误差,在定常问题的模拟中,这种误差可以随着迭代逐渐消除,然而在非定常问题的模拟中,这种误差往往会积累甚至导致计算崩溃.文章将基于特征线理论的激波辨识技术应用到激波装配中,根据已有流场信息准确判断激波的位置.对于定常问题,该方法的应用加速了收敛速度;对于非定常问题,该方法的应用可以极大地避免初始误差的产生.      

面向虚拟试验的可视化应用生成工具研究与实现

虚拟试验能够很好的辅助实物试验,缩短型号研制周期,降低研制费用。虚拟试验应用工程是开展虚拟试验的基础,本文基于GEF图形编辑器,研究并实现了一种面向虚拟试验可视化应用生成工具,具有可视化应用工程编辑、应用工程框架代码生成等功能。支持在可视化界面中定义VOM图元和APP图元之间的发布、订阅关系,最终生成应用工程框架,并通过应用实例验证了该可视化应用生成工具的实用性,较好的提高了虚拟试验应用工程的开发效率。     

A Highly Selective Fluorescent Probe for Detection of Biological Samples Thiol and Its Application in Living Cells

Probe 1 was designed and synthesized as a new fluorescent molecular probe for thiols in PBS buffer at physiological condition. This fluorescent molecular probe consists of a thiol reaction moiety bound to a coumarin fluorophore. Its fluorescence quantum yield is low, but a drastic enhancement of fluorescence intensity was observed in the presence of thiols. Possible interference with other analytes was examined. Probe 1 displays a highly selective fluorescent enhancement with thiols, and the probe was successfully applied to thiols determination in intracellular, in human urine and blood samples.     

太赫兹光谱法和GA-BP在甲醇浓度检测的应用

在常温常压下,利用光电导天线式太赫兹时域光谱仪和自行设计的气室,在0.1~3.0 THz范围内对甲醇气体进行太赫兹时域光谱测试,测试结果表明,甲醇气体在1.0~3.0 THz没有明显的吸收峰,但是在0.1~1.0 THz波段存在明显的吸收峰。为了准确测定甲醇气体的浓度,根据甲醇气体在0.1~1.0 THz范围内的15处不同的位置处的特征吸收峰强度和甲醇气体浓度的关系,对十五组不同浓度的甲醇气体进行检测,获得了在特征吸收峰处的差异曲线。基于误差反向传播(BP)神经网络的函数逼近特点,并利用遗传算法(GA)收敛速度较快,不宜陷入局部极值的优点,采用GA优化BP神经网络的初始的权值和阈值,构建了以预测甲醇浓度为目的的数学模型。结果表明,该网络模型适用于体积浓度范围为0.028 3~0.424 6 m3·L-1的甲醇的浓度预测,两组样本的平均相对标准误差为1.7%,平均回收率为98%,神经网络误差精度10-1,实测值与期望值的相关系数为0.996 77,基本达到理想预测结果。本成果不仅获得了甲醇气体在太赫兹频段的实验数据,而且发现太赫兹时域光谱法和GA-BP神经网络相结合的方法能有效地检测甲醇气体的体积浓度,为检测甲醇气体浓度提供新的方法。