中波红外制冷型光学系统消热差设计

对比了典型消热差方法的优劣,探讨光学被动式消热差的基本理论。在此基础上,根据系统要求的温度范围 60℃～90℃,在常温初始结构的基础上,利用Zemax软件的多重结构和自动热分析功能增加其他温度结构,运用光学被动式消热差方法进行热平衡和像差平衡,最终设计出一套中波制冷型消热差光学系统。光学设计时以探测器冷阑作为系统孔径光阑,实现了100%冷阑匹配。结构材料使用铝,光学材料为硅、锗和硒化锌,将它们组合消热差。系统在-60℃～90℃温度范围内,最大离焦量小于1倍焦深,空间分辨率17 lp/mm处,光学调制传递函数(MTF)值均大于0.74,接近衍射极限,点列图弥散斑均未超出单像元尺寸范围。     

气相色谱-三重四极杆串联质谱稳定同位素稀释法测定被动吸烟儿童尿液中的可丁宁

建立了被动吸烟儿童尿液中可丁宁的气相色谱-三重四极杆串联质谱（GC-MS/MS）稳定同位素稀释测定方法。尿液经过三氯甲烷提取、净化,采用气相色谱-三重四极杆串联质谱多反应监测（MRM）模式测定,以可丁宁-d₃稳定同位素为内标,定量测定和确证被动吸烟儿童尿液中的可丁宁;在0.1~10 μg/L可丁宁质量浓度范围内方法的线性关系良好,相关系数r>0.998;空白尿液中添加可丁宁0.1、1.0和10 μg/L,回收率为79.2%~112.8%,相对标准偏差在2.1%~5.8%之间;方法定量限达到0.1 μg/L。该方法准确、灵敏、快速,适用于家庭被动吸烟儿童尿液中可丁宁的测定。     

Effect of passive plates on vertical instability in the EAST tokamak

The effect of passive plates on vertical displacement control in the EAST tokamak is investigated by open loop experiments and numerical simulations based on a rigid displacement model.The experiments and simulations indicate that the vertical instability growth rate is reduced by a factor of about 2 in the presence of the passive plates,where the adjacent segments are not connected to each other.The simulations also show that the vertical instability growth rate is reduced by a factor of about 10 if all adjacent segments on each passive plate loop are connected to each other.The operational window is greatly enlarged with the passive plates.     

基于动态混沌映射的三维加密正交频分复用无源光网络

提出了一种基于混沌映射的三维加密正交频分复用无源光网络保密通信系统.该系统通过相关性检测锁定收发端混沌系统参数,实现收发双方混沌系统同步;并利用同步混沌系统生成密钥,实现符号扰动以及二重子载波加密.该加密方案的密钥空间超过10~(86),能够有效对抗穷举攻击.实验实现了13.3 Gb/s基于64进制正交幅度调制的加密正交频分复用信号在25 km标准单模光纤中的传输,并完成了信息的有效解密.     

Performance of low-power RFID tags based on modulated backscattering

Ultra Wideband (UWB) modulated backscattering (MBS) passive Radio-Frequency IDentification (RFID) systems provide a promising solution to overcome many limitations of current narrowband RFID devices. This work addresses the performance of such systems from the point of view of the radio channel between the readers and the tags. Such systems will likely combine several readers, in order to provide both the detection and localization of tags operating in MBS. Two successive measurements campaigns have been carried out in an indoor reference scenario environment. The first is intended to verify the methods and serves as a way to validate the RFID backscattering measurement setup. The second represents a real use case for RFID application and allows one to quantitatively analyze the path loss of the backscattering propagation channel.     

Effective transport of passive particles induced by chiral-active particles in microchannel

Transport of passive particles induced by chiral-active particles in microchannel is investigated by using the overdamped Langevin dynamics simulation in a two-dimensional model system. Due to the chirality of active particles and special structure of microchannel, effective ratchet transport of passive particles is achieved. Effective transport of passive particles depends on the width of microchannel(d), the density(ρ), and the angular velocity(ω) of chiral-active particles.There exist optimal parameters for d and ω at which the transport efficiency for passive particles takes its maximal value.This investigation can help us understand the necessity of active motion for living systems to maintain a number of vital processes such as materials transport inside cells and the foraging dynamics of mobile organisms.     

MoEDAL – a new light on the high-energy frontier

In 2010, the MoEDAL (MOnopole and Exotics Detector at the LHC) experiment at the Large Hadron Collider (LHC) was unanimously approved by European Centre for Nuclear Research’s Research Board to start data taking in 2015. MoEDAL is a pioneering experiment designed to search for highly ionising manifestations of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles. Its groundbreaking physics programme defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; does magnetic charge exist; what is the nature of dark matter; and, how did the Big Bang develop. MoEDAL’s purpose is to meet such far-reaching challenges at the frontier of the field. The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors – analysed offline by ultra fast scanning microscopes – sensitive only to new physics. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL’s radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array. A new MoEDAL sub-detector designed to extend MoEDAL reach to mini-charged, minimally ionising particles is under study.     

采用3×3耦合器的分布反馈式光纤激光传感器解调技术

为了实现分布反馈式光纤激光传感器(DFB FL)大动态范围、稳定解调,建立了基于3×3耦合器的迈克尔逊干涉仪解调系统。对该系统所采用的对称解调算法(NPS)和反正切解调算法进行了深入研究。首先,介绍了基于3×3耦合器解调算法的原理及耦合器不对称时的调校方法。接着,对干涉仪所需最小非平衡路径长度的选取与系统强度噪声、激光器频率噪声的关系进行了分析。最后,针对NPS算法与反正切算法最大可解调信号幅度进行了分析对比,并研究了微分器对对称解调方法解调范围的影响。实验结果表明:NPS算法动态范围高于反正切算法,微分器的幅频特性不理想会减小解调动态范围。在采样频率为125 k Hz、信号频率为1 k Hz、干涉仪非平衡路径为100 m时,NPS算法与反正切算法的动态范围分别达到96 d B和90 d B。用解调前调校的方法,基于3×3耦合的解调方法动态范围大,能够实现稳定解调,满足工程应用要求。     

Passive Tracking of Multiple Underwater Targets in Incomplete Detection and Clutter Environment

A major advantage of the use of passive sonar in the tracking multiple underwater targets is that they can be kept covert, which reduces the risk of being attacked. However, the nonlinearity of the passive Doppler and bearing measurements, the range unobservability problem, and the complexity of data association between measurements and targets make the problem of underwater passive multiple target tracking challenging. To deal with these problems, the cardinalized probability hypothesis density (CPHD) recursion, which is based on Bayesian information theory, is developed to handle the data association uncertainty, and to acquire existing targets’ numbers and states (e.g., position and velocity). The key idea of the CPHD recursion is to simultaneously estimate the targets’ intensity and the probability distribution of the number of targets. The CPHD recursion is the first moment approximation of the Bayesian multiple targets filter, which avoids the data association procedure between the targets and measurements including clutter. The Bayesian-filter-based extended Kalman filter (EKF) is applied to deal with the nonlinear bearing and Doppler measurements. The experimental results show that the EKF-based CPHD recursion works well in the underwater passive multiple target tracking system in cluttered and noisy environments.     

基于LabVIEW的高分辨率光谱测试系统(英文)

提出了一种基于LabVIEW的无源器件光谱测试方案.通过LabVIEW编程控制可调谐激光器、可编程光滤波器、光功率计和数据采集平台,获得了具有不同传递函数的光谱特性.实验中激光器的扫描速度为10nm/s,扫描范围为10nm,数据采集卡的采样速率为1MS/s,结果表明:单个器件的光谱测试可以在1s内完成,光谱分辨率可达1pm;与利用宽带光源和光谱分析仪的传统光谱测试方法相比,所提方案的测试性能可达到传统方案水平,且能显示更精细的光谱细节.该方案能应用于有高分辨率、快速和高效要求的光谱测试中.