UWB Perimeter Surveillance

This program will develop an automated and unmanned ultra-wide band (UWB) perimeter surveillance sensor designed to provide detection and tracking of personnel and vehicles at the perimeter of critical areas such as military installations and other such facilities. This effort describes the work being done for the protection of high value assets using a compact system which incorporates two technologies to enhance the probability of detection in stressing environments     

Intelli-FIELDTM: the next generation electrostatic fielddisturbance sensor

Outdoor perimeter volumetric field disturbance sensors must reliably detect perturbations to the field caused by an intruder, while rejecting noise and environmental changes that may be orders of magnitude greater than the target response. Currently, E-Field(R) systems are widely deployed in nuclear, correctional, and industrial sites to provide perimeter security. These systems are effective in rejecting the majority of noise and environmental stimuli through combined fixed attribute threshold comparison techniques. However, some environmental stimuli closely mimic target stimuli, so improved discrimination techniques have been sought. We describe the results of current studies and investigations of electrostatic sensor system response to targets and to various environmental changes. Fundamental principles in the character of sensor response to these varied stimuli are discussed. Techniques and methods that may be used to exploit the difference between intruder and environmental responses, while using cost-effective discrimination methods, are described. We show how the new Intelli-FIELD system was created, using currently available technologies, to provide both excellent detection properties, and an extremely low nuisance alarm rate, while, at the same time, greatly simplifying installation, calibration, and maintenance. The details of the new system hardware components and test results from initial field installations are described. A comparison of field performance with the previous E-Field product is provided to indicate the advantages of this new sensor technology     

Fence vibrations [intruder detection]

Many Perimeter Intrusion Detection Systems (PIDS) use microphonic sensors mounted on fences to detect intruder attacks. Vibrations in the fence are detected and analysed to determine whether they represent an intrusion attempt. The signals from the fence are processed to filter out as many false alarms as possible. It is important that the output from the sensors is linear along the fence, to ensure that there is no point on the perimeter less sensitive to intruder attack. The investigation reported in this paper aims to discover whether the performance of acoustic detection systems could be improved through research into fence acoustics. Using models of fence vibrations, sensors could be positioned to obtain a more linear response. In addition, through knowledge of the fence vibrations produced by both real attacks and the typical causes of false alarms, a system could be designed which could better distinguish between them, giving a lower false alarm rate and increased detection performance. Characteristic profiles were found for the different forms of attack to the fence. Although the investigation is still in its early stages, these attack profiles suggest that a new type of detection system could be designed based on profile recognition     

热障涂层在线/离线磷光温度测量技术研究进展

精确测量涡轮叶片表面热障涂层温度对航空发动机和地面燃气轮机设计和研制具有极其重要的意义。近年来,基于热像磷光材料磷光特性的热障传感涂层在线测温技术与热历史磷光涂层离线测温技术得到了迅猛发展。前者通过在线测量高温下磷光信号来获取实时温度信息,后者通过离线测量经高温服役后的磷光材料不可逆磷光信号变化来获取服役温度信息。这两项技术都适用于高温、高腐蚀环境下热障涂层非干涉、非接触式和高精度温度测量,具有广阔的应用前景。从热障涂层在线/离线测温原理与方法、磷光材料与制备及应用3个方面详细介绍了热障涂层在线/离线测温技术的研究现状与技术特点,并对这两种技术的发展进行了展望。     

An alternative to traditional software rehosting

This paper describes one alternative to rehosting TPS software to newer computer platforms. It describes the solution that Southwest Research Institute (SwRI) used to solve a problem with re-engineering legacy software into a modern object-oriented language. The advantages gained by this method are more advanced instruction to the operator (such as pictures and movies), flexible reporting scheme to diagnose system problems, and ease of software maintenance. This solution uses commercially available products including National Instruments/spl trade/ TestStand/spl trade/ and LabVIEW/spl trade/ and Microsoft/spl reg/ Visual Basic/spl reg/. The system is a four-tiered architecture to drive all test execution. The user interface is written in Visual Basic and allows the user to interact with the test execution when needed. This user interface in turn calls tests that are written in TestStand, and finally the individual tests call driver functions written in LabVIEW. A database serves as a repository for all test results, displays, and test limits. The use of this database allows for easy querying of measurement data to analyze trends in failures that help diagnose specific problems. By using this database, all test limits and test displays are contained in one central location that enables engineers to change these displays and limits on the fly without needing to change or even understand any test code. One other benefit of this data containment is that all Government classified data is separated out of the code and stored as one file, instead of in various locations as it was in the original source code.     

Leaky Coaxial Cable Resource Protection Sensor Performance Analysis

The performance of an RF intrusion detection system which uses a leaky coaxial cable sensor is analyzed. A simple cable sensor field model is assumed which gives good agreement between the computed response and observation. Expressions that describe the performance of several deployment configurations and receiver types are developed. The probability of detection and the zone of containment are computed and their uniformity is examined as a function of cable propagation constants.     

Sensor fusion for intelligent alarm analysis

The purpose of an intelligent alarm analysis system is to provide complete and manageable information to a central alarm station operator by applying alarm processing and fusion techniques to sensor information. This paper discusses the sensor fusion approach taken to perform intelligent alarm analysis for the Advanced Exterior Sensor (AES). The AES is an intrusion detection and assessment system designed for wide-area coverage, quick deployment, low false/nuisance alarm operation, and immediate visual assessment. It combines three sensor technologies (visible, infrared, and millimeter wave radar) collocated on a compact and portable remote sensor module. The remote sensor module rotates at a rate of 1 revolution per second to detect and track motion and provide assessment in a continuous 360° field-of-regard. Sensor fusion techniques are used to correlate and integrate the track data from these three sensors into a single track for operator observation. Additional inputs to the fusion process include environmental data, knowledge of sensor performance under certain weather conditions, sensor priority, and recent operator feedback. A confidence value is assigned to the track as a result of the fusion process. This helps to reduce nuisance alarms and to increase operator confidence in the system while reducing the workload of the operator     

Brightness-independent start-up routine for star trackers

Initial attitude acquisition by a modern star tracker is investigated here. Criteria for efficient organization of the on-board database are discussed with reference to a brightness-independent initial acquisition algorithm. Star catalog generation preprocessing is described, with emphasis on the identification of minimum star brightness for detection by a sensor based on a charge coupled device (CCD) photodetector. This is a crucial step for proper evaluation of the attainable sky coverage when selecting the stars to be included in the on-board catalog. Test results are also reported, both for reliability and accuracy, even if the former is considered to be the primary target. Probability of erroneous solution is 0.2% in the case of single runs of the procedure, while attitude determination accuracy is in the order of 0.02/spl deg/ in the average for the computation of the inertial pointing of the boresight axis.     

翼刀附面层控制二次流技术的研究现状及发展前景

翼刀技术是附面层控制技术的一种，主要是通过有效阻断端壁附面层或叶片吸力面附面层近端壁处低能流体的横向迁移或径向迁移以及反向翼刀涡的影响来控制二次流。国外对此项研究起步较早，重点集中在对汽轮机叶栅的实验研究上；而国内在近几年，才开始了对压气机叶栅中应用翼刀技术的实验和计算研究工作。     

Synthetic Vision-a view in the fog

A program called the Synthetic Vision Technology Demonstration Program, which is aimed at evaluating and demonstrating technologies permitting aircraft to land in very low visibilities over a wide range of airports, is described. The idea is to provide an electronic image of the runway to the pilot on a head-up display with an overlay on the display of symbology providing all the navigation and performance information needed to fly and land the aircraft. Millimeter-wave radar, infrared sensor, head-up display, and airborne computer processing technologies are being tested. The theoretical performance of the system concept at 35 GHz is compared to the actual performance of the 35-GHz experimental demonstration system for typical approach and runway intrusion detection conditions     

光纤传感器在测量领域的发展与应用

光纤传感器是近年来发展起来的一种新型传感器的技术，本文介绍了两种不同类型的新型光纤传感器的结构原理及在不同领域的应用，并介绍了光纤传感器在测量领域广阔的应用前景。     

发展单兵星敏导航装备的必要性及技术特点

星光导航不受电磁干扰、能提供绝对姿态信息，具有重大战略意义。目前的星敏主要是为空天基导航而发展的，将其应用于单兵导航是否必要、需克服哪些技术难点、能达到怎样的效果等，都是值得探索的问题。为此，首先论述了发展单兵星敏导航装备的必要性，包括：不受电磁干扰破坏，是其他单兵导航装备失效时的保底装备；定向精度高，能弥补单兵卫星导航装备无法定向的缺陷；已突破部分气象因素限制，具备了全天时导航条件等。然后探讨了单兵星敏导航与空天基星敏导航、卫星导航、天文大地测量等比较所具有的不同技术特点。提出了发展单兵星敏导航装备需解决的关键技术问题，包括：气象因素影响的消减、时间基准和电源的长期维持、系统探测性能与系统小型化的平衡等。研究结果可为发展单兵星敏导航技术、设计研制单兵星敏导航系统提供参考。     

New assignment-based data association for tracking move-stop-move targets

We present a new assignment-based algorithm for data association in tracking ground targets employing evasive move-stop-move maneuvers using ground moving target indicator (GMTI) reports obtained from an airborne sensor. To avoid detection by the GMTI sensor, the targets deliberately stop for some time before moving again. The sensor does not detect a target when the latter's radial velocity (along the line-of-sight from the sensor) falls below a certain minimum detectable velocity (MDV). Even in the absence of move-stop-move maneuvers, the detection has a less-than-unity probability (P/sub D/<1) due to obscuration and thresholding. Then, it is of interest, when a target is not detected, to develop a systematic technique that can distinguish between lack of detection due to P/sub D/<1 and lack of detection due to a stop (or a near stop). Previously, this problem was solved using a variable structure interacting multiple model (VS-IMM) estimator with a stopped target model (VS-IMM-ST) without explicitly addressing data association. We develop a novel "two-dummy" assignment approach for move-stop-move targets that considers both the problem of data association as well as filtering. Typically, in assignment-based data association a "dummy" measurement is used to denote the nondetection event. The use of the standard single-dummy assignment, which does not handle move-stop-move motion explicitly, can result in broken tracks. The new algorithm proposed here handles the evasive move-stop-move motion by introducing a second dummy measurement to represent nondetection due to the MDV. We also present a likelihood-ratio-based track deletion scheme for move-stop-move targets. Using this two-dummy data association algorithm, the track corresponding to a move-stop-move target is kept "alive' during missed detections both due to MDV and due to P/sub D/<1. In addition, one can obtain reductions in both rms estimation errors as well as the total number of track breakages.     

Explicit formulas for two state Kalman, H/sub 2/ and H/sub /spl infin// target tracking filters

The continuous time, two state, target tracking problem is considered from the Kalman, H/sub 2/, and H/sub /spl infin// filter viewpoint. While previous treatments were numerical in nature, analytic transient responses and infinite horizon solutions with analytic performance expressions are presented here. Tracking indices, involving the maneuver and measurement uncertainties, are shown to have a role for both the steady state and transient responses. In addition, the H/sub /spl infin// tracker has a sensor index involving the performance bound and measurement uncertainty, which, along with the tracking index, plays a significant role in the H/sub /spl infin// tracker expressions. Analytical expressions for the probability of target escape, the probability that the target position will be outside the radar beamwidth (BW), are developed not only to compare the performance of various trackers, but also as a design tool to meet tracking specifications. Examples illustrate the performance of the target trackers as a function of the error gain upper bound.     

Integrating VISA, IVI and ATEasy to migrate legacy test systems

New software technologies, such as VISA and IVI, continue to bring the industry toward greater standardization. The benefit to the integrator is reduced costs through reuse of the same hardware and software. The benefit to the customer end-user is lower costs by reducing modification and support through the life-cycle to the test station. However, while we position ourselves for the future with PXI and these software technologies, we must still provide support for VXI, GPIB, and instrument drivers that use current software technologies. Using a number of additional tools such as National Instrument's Measurement and Automation Explorer and Geotest's ATEasy, we can have the power of these tools today while waiting for wider acceptance and support of the newer VISA and IVI technologies. We are just now seeing the development of IVI drivers and the ink is still wet on the VISA specification for PXI. ATEasy provided the structure necessary to use these technologies with the current technology. This paper explores the process of implementing and integrating the system driver and instrument drivers for a PXI-based test station for the TOW2 optical sight sensor.     

Use of laser scanning technology for perimeter protection

The Police Scientific Branch (PSDB) is part of the Crime Reduction and Community Safety Group (CRCSG) of the Home Office. Part of PSDB's work includes evaluating and assessing new technologies for perimeter intrusion detection. Laser scanning technology has been used for some time in a range of industrial and commercial applications. These span from detecting hands when they are close to dangerous machinery to preventing collisions at container ports and monitoring manufacturing processes. Laser scanners are non-contact measurement systems and scan their surroundings two-dimensionally. This describes the application of laser scanning to physical security, including modifications to such systems for their use as perimeter intrusion detection systems (PIDS). In these systems, motion detection is provided by a pulsed laser beam by measuring the propagation time for the reflected beam to return to its source. Using this information, a contour plot of the surrounding area is built up. Once this contour information has been obtained, the detector can recognise the addition of an object to its field of view through a change in the programmed surroundings. Consequently, the size, shape, and direction of targets moving in the frame can be assessed and an alarm output given, if required. This explains the main operating principles of the systems, including mechanisms for the detection of a potential intruder and the handling of false alarms. Detection capabilities and the potential for low false alarm rates will be described, along with configurations for operational deployment.     

Nullifying ACF grating lobes in stepped-frequency train of LFM pulses

An effective way to increase the bandwidth of a coherent pulse-train is to add a frequency step /spl Delta/f between consecutive pulses. A large /spl Delta/f implies a large total bandwidth, hence improved range resolution. However, when the product of the frequency step times the pulse-duration t/sub p/, is larger than one (t/sub p/ /spl Delta/f > 1), the autocorrelation function (ACF) of the stepped-frequency pulse-train suffers from ambiguous peaks, known as "grating lobes." It is well known that replacing the fixed-frequency pulses with linear FM (LFM) pulses of bandwidth B can reduce those grating lobes. We present a simple analytic expression for the ambiguity function (AF) and ACF of such a signal and derive from it very simple relationships between /spl Delta/f, B, and t/sub p/ that will place s exactly where the grating lobes are located, and thus remove them completely.     

防风网对煤堆遮风效果的风洞实验研究

为了考察防风网对堆场煤堆的遮风效果,进行了防风网与煤堆之间区域的流场可视化实验。使用风洞模拟大气边界层条件,并将开孔率为38．5％的防风网模型布置在煤堆模型前方。实验中采用粒子成像测速（PIV）系统测量了防风网和堆场区域的平均风速分布,并且获得了煤堆表面的摩擦风速分布,进一步估算煤堆起尘量的变化情况。实验发现,防风网可有效降低煤堆表面迎风区域的摩擦风速,而对背风面的流场分布影响较小。研究结果可为防风网的遮护作用提供一定的实验支持。     

不同高度端壁翼刀对压气机叶栅二次流影响的数值模拟

对CDA常规直叶栅和三种具有不同高度端壁翼刀压气机叶栅内三维粘性流场进行了数值模拟。计算结果表明,翼刀偏向吸力面一侧上方有反向翼刀涡产生;随着翼刀高度增加,对横向流动的阻断作用增强的同时,翼刀周围损失有所增加;1/3附面层厚度为加装翼刀的最佳翼刀高度,可使叶栅损失降低9%。实验与计算结果吻合较好。