Imaging marine geophysical environments with vector acoustics

Using vector acoustic sensors for marine geoacoustic surveys instead of the usual scalar hydrophones enables one to acquire three-dimensional (3D) survey data with instrumentation and logistics similar to current 2D surveys. Vector acoustic sensors measure the sound wave direction directly without the cumbersome arrays that hydrophones require. This concept was tested by a scaled experiment in an acoustic water tank that had a well-controlled environment with a few targets. Using vector acoustic data from a single line of sources, the three-dimensional tank environment was imaged by directly locating the source and all reflectors.     

TEMPERATURE PROFILES WITHIN A MOVING PLATE IN A COOLING FLUID USING A HEAT FLUX CLAMP ASSOCIATED TO AN INVERSE ALGORITHM

An original apparatus including two heat flux sensors installed in a clamp is developed to analyze heat transfer during the cooling of a moving plate in a water tank. Heat flux recordings are processed following an inverse methodology to determine non-symmetrical spatial temperature profile in the plate thickness. This method is non-intrusive and specially suitable for low conductivity materials like polymers.     

多移动机器人的目标跟踪研究

本文主要对低温真空球罐三维可视化温度在线监测系统进行介绍,在真空球罐外罐内壁、内罐外壁、夹层、垂直支架等部位安装温度传感器,通过LabVIEW数据采集板卡实时采集温度信号,在Pro－E中建立球罐三维模型,划分网格后导入到LabVIEW环境中,将采集到的温度信号通过空间插值算法映射到模型中,直观显示真空球罐的整体温度信息,同时,通过LabVIEW三维模型场景对象属性节点和方法节点开发了模型隐藏、剖分、透视以及拾取传感器点等多样化功能,该套在线监测系统已经投入使用,整体性能表现优异,尤其是直观新颖的三维可视化操作界面受到操作人员的一致好评。     

直升机驾驶员夜间飞行观察导航系统

 根据直升机驾驶员夜间飞行观察系统（NVPS)的特点,对NVPS的环境适应性设计、光电传感器选取以及控制系统设计等问题进行仿真分析与计算。在系统热设计中热像仪传感器通过传导、对流或辐射将热传递到壳体上,由系统采取统一的散热措施,给出NVPS中伺服系统的2个主要工作模式,即随动与锁定的控制回路原理。仿真和计算结果表明：设计的NVPS系统中光学系统焦距为14mm,f/#为1.9,瞬时视场为2.13mrad,透射比≥80%;NVPS稳定性能可达到0.1mrad,转弯速度为30°/s,机动飞行期间的锁定误差不超过0.1mrad,对头盔的位置随动误差不超过1.5mrad,系统随动速度可达到250°/s,角加速度可达到500°/s2。     

Detector Systems for Medical Diagnostics

Medical systems are reviewed, which are suitable to image x-ray patterns obtained for medical diagnosis. Semiconductor sensors are utilized for detection of x-rays in the range from 5 to 150 keV. The applications range from mammography to dental and full body exposures. Silicon-, GaAs, and CdTe sensors as the basic choices for room temperature operation are being compared. Processing techniques for different substrates are essential to facilitate a reliable sensor system. Pixel, 3D and CCD systems will be compared. Readout systems like the novel photon counting technique will be presented and compared to integrating methods. Finally methods for comparing the different sensor systems will be shown.     

Acoustic emission transducers--development of a facility for traceable out-of-plane displacement calibration

Acoustic emission (AE) is a widely used technique that has been employed for the integrity testing of a range of vessels and structures for many years. The last decade has seen advances in signal processing, such that the reliability of AE technology is now being recognised by a wider range of industries. Furthermore, the need for quality control at the manufacturing stage, and requirements of in-service testing, is encouraging the issue of traceable measurements to be addressed. Currently, no independent calibration service for acoustic emission transducers is available within Europe. The UKs National Physical Laboratory (NPL) is undertaking work to develop a measurement facility for the traceable calibration of AE sensors. Such calibrations can contribute to greater acceptance of AE techniques in general, by meeting quality system and other traceability requirements. In this paper the key issues surrounding the development of such a facility are reviewed, including the need to establish repeatable AE sources, select suitable test blocks and to understand the limitations imposed by AE sensors themselves. To provide an absolute measurement of the displacement on the surface of a test block, laser interferometry is employed. In this way the output voltage of an AE sensor can be directly related to the displacement detected at the block surface. A possible calibration methodology is discussed and preliminary calibration results are presented for a commercially available AE sensor, showing its response to longitudinal wave modes.     

Proximal and remote sensing techniques for mapping of soil contamination with heavy metals

Heavy metal soil contamination is a severe environmental problem globally, and its mapping is vital for environmental managers and policymakers to determine its distributions and hotspots. This paper reviewed multiple proximal and remote sensing spectroscopy for convenient and inexpensive method of obtaining soil reflectance spectroscopy or environmental covariates, which can be used for mapping heavy metal soil contamination. Furthermore, spatial prediction using proximal remote-sensed data and environmental covariates was discussed. We suggested that mapping of the spatial distributions of metal species may be important due to the different bioavailabilities and toxicities of various species. The assimilation of multiple proximal/remote-sensed sensors may promote the horizontal and vertical mapping of soil heavy metals. Moreover, combining the advantages of satellite and unmanned aerial vehicle-based hyperspectral imaging systems will facilitate the development of a space–aeronautic incorporation hyperspectral observation technology that can monitor soil environment rapidly and accurately at a large scale.     

连续搅拌反应器中自催化化学反应的同步与控制

讨论了由两个连续搅拌反应器组成的化学反应体系的同步问题. 基于Lyapunov稳定性理论,提出了设计控制函数的方法,分别探讨了入料溶液的流速恒定和存在周期微扰两种情况下使反应实现同步的耦合强度范围. 用数值模拟验证了方法的有效性. 结果表明该方法不仅适用于自治系统,同时也适用于具有周期扰动的非自治系统. 关键词： 同步与控制 化学反应 连续搅拌反应器 周期扰动     

新型分布式光纤拉曼光子温度传感器系统

讨论了2kmFGC-W2，10kmFGC-W10和30kmFGC-W30分布式光纤拉曼光子温度传感器系统的工作原理和系统的结构，介绍了国内外分布式光纤拉曼光子温度传感系统的研究现状，提出了分布式光纤拉曼光子温度传感器系统的发展方向。     

Microcavity plasmonics: strong coupling of photonic cavities and plasmons

The understanding of light‐matter interactions at the nanoscale lays the groundwork for many future technologies, applications and materials. The scope of this article is the investigation of coupled photonic‐plasmonic systems consisting of a combination of photonic microcavities and metallic nanostructures. In such systems, it is possible to observe an exceptionally strong coupling between electromagnetic light modes of a resonator and collective electron oscillations (plasmons) in the metal. Furthermore, the results have shown that coupled photonic‐plasmonic structures possess a considerably higher sensitivity to changes in their environment than conventional localized plasmon sensors due to a plasmon excitation phase shift that depends on the environment.     

非本征F-P局部放电光纤传感器设计及灵敏度分析

为解决超声波法检测电力设备局部放电灵敏度低问题,提出一种采用石英膜片的全电介质结构的光纤法 珀超声传感器设计方法。为获得适于局放检测频响特性的法 珀传感器,根据弹性力学原理分析法 珀传感器固有频率随膜片尺寸参数变化规律,利用ANSYS有限元仿真方法设计3种不同结构尺寸的法 珀传感器。在绝缘油箱中采用信号发生器驱动压电陶瓷传感器发射50 kHz~250 kHz超声波,获得F P传感器的幅频特性曲线。F P1~F P3对板 板电极局放声信号检测实验表明,设计传感器一阶固有频率在150 kHz处可有效检测局放,且相同固有频率下F P传感器灵敏度随膜片厚度减小而显著提高。相同结构参数下腔长为130 m和100 m的F P传感器检测灵敏度前者是后者的2.47倍,实验结果表明增加F P腔长可提高传感器局放检测灵敏度。     

Low-cost active optical system for fire surveillance

Detection of smoke plumes using active optical sensors provides many advantages with respect to passive methods of fire surveillance. However, the price of these sensors is often too high as compared to passive fire detection instruments, such as infrared and video cameras. This article describes robust and cost effective diode-laser optical sensor for automatic fire surveillance in industrial environment. Physical aspects of the sensing process allowing to simplify the hardware and software design, eventually leading to significant reduction of manufacturing and maintenance costs, are discussed. The article is published in the original.     

Optical fibre sensors for earth sciences: : from basic concepts to optimising glass composition for high temperature applications

This paper reviews the technical evolution of optical fibre sensors relevant to earth sciences with particular reference to high temperature measurements. Optimisation of fibre composition and system design to fully realise the potential of these sensors has led to the substantial advances in both distributed and point sensor systems. Applications of these sensors in the field of earth sciences are discussed to provide a deeper understanding of the potential for monitoring geodynamical and chemical processes in areas of high seismic and volcanic risk.     

火控性能参数静态测试系统

为提高武器火控静态性能指标的测试精度,设计了火控性能参数静态测试系统,用于对火炮炮身松动量、过渡过程品质、刚性、漂移速度及最大调炮速度等参数进行测试。通过相对测试的方法,运用光学测量头拍摄炮口在坐标靶上的相对运动图像,计算出相关参数。采用弹性胀套的连接方式,实现了静态测量头的可靠安装及方便拆卸。结果表明:在-30℃～+50℃环境温度下,光学系统的MTF值可达0.6以上,接近系统的衍射极限;当2=9.15,f＝50 mm时,静态测角精度0.2 mil。安装夹具适应100 mm、105 mm、125 mm火炮的固联安装,测试系统可对某型坦克炮管的相关指标进行实测,也可广泛应用于高炮、装甲车辆、舰载火控系统、坦克等多种武器装备。     

Cosmic Ray Spectrum and Composition from Three Years of IceTop and IceCube

Physics of Atomic Nuclei - The IceCube Observatory includes both a deep in-ice array of 86 strings of sensors, and a surface array of 81 stations of frozen water tank detectors (IceTop). These...     

航天太阳敏感器的应用与发展

综述了当前广泛应用的数字太阳敏感器的原理、系统设计、应用领域和发展现状。首先,叙述了太阳敏感器的工作原理;数字太阳敏感器一般采用小孔成像的原理,包括光学系统、光电探测器和信息处理单元3个部分。其次,介绍了太阳敏感器的光学系统,包括单光孔、单狭缝、多光孔和多狭缝等多种入光形式。然后,从常规光电探测器件和集成了光学系统、图像传感器和信息处理单元的探测器两个层面,说明了太阳敏感器涉及的光电探测器的发展,并介绍了相应的太阳像点中心提取算法。最后,给出了航天太阳敏感器的现有产品及应用现状,讨论了未来航天太阳敏感器面临的挑战和发展趋势。     

Silicon detector systems in high energy physics

Silicon sensors have been used in High Energy Physics for about 25 years. They have been continuously improved to meet new requirements and challenges. Based on a simple detection principle many different types of silicon sensors have been developed. This article gives an introduction to the basic properties of silicon sensors and the related readout electronics. Then several silicon sensor types are described, which are the building blocks of detectors for tracking and scintillator readout. Besides reviewing state of the art sensor types some new developments will be discussed. This includes extremely radiation hard sensors, novel sensors for photon counting and especially trends to integrate sensor and readout electronics into monolithic devices. Finally some selected examples of large detector systems in existing or planned experiments will be reviewed.     

Electromechanical properties of metallic,quasimetallic, and semiconducting carbon nanotubes under stretching

An electromechanical system is constructed to explore the electrical properties of various types of suspended single-walled carbon nanotubes under the influence of tensile stretching. Small band-gap semiconducting (or quasimetallic) nanotubes exhibit the largest resistance changes and piezoresistive gauge factors ( approximately 600 to 1000) under axial strains. Metallic nanotubes exhibit much weaker but nonzero sensitivity. Comparison between experiments and theoretical predictions and potential applications of nanotube electromechanical systems for physical sensors (e.g., strain gauges, pressure sensors, etc.) are discussed.     

Toward a Comparison of Classical and New Privacy Mechanism

In the last decades, the development of interconnectivity, pervasive systems, citizen sensors, and Big Data technologies allowed us to gather many data from different sources worldwide. This phenomenon has raised privacy concerns around the globe, compelling states to enforce data protection laws. In parallel, privacy-enhancing techniques have emerged to meet regulation requirements allowing companies and researchers to exploit individual data in a privacy-aware way. Thus, data curators need to find the most suitable algorithms to meet a required trade-off between utility and privacy. This crucial task could take a lot of time since there is a lack of benchmarks on privacy techniques. To fill this gap, we compare classical approaches of privacy techniques like Statistical Disclosure Control and Differential Privacy techniques to more recent techniques such as Generative Adversarial Networks and Machine Learning Copies using an entire commercial database in the current effort. The obtained results allow us to show the evolution of privacy techniques and depict new uses of the privacy-aware Machine Learning techniques.     

An Approximate Theoretical Model of Surface Plasmon Resonance Optical Waveguide and Fibre-optic Sensors

Optical surface plasmon resonance (SPR) excitation can be theoretically depicted and discussed using Fresnel’s equations. However, Fresnel’s equations cannot explicitly give expressions to reflect the characteristics of SPR systems, especially in SPR optical waveguide and fibre-optic sensors. In this paper a mathematical model based on the approximation proposed by Kretschmann in bulk optics is presented to describe the characteristics of SPR optical waveguide and fibre-optic sensors. The results show that the model keeps high accuracy when used in the area close to the minimum reflection, at which the resonance condition is achieved. This model can be used to analytically estimate the performance of SPR optical waveguide sensors, and SPR fibre-optic sensors in meridional rays approximation.