Low threshold particle arrays

While atmospheric Cherenkov telescopes have a small field of view and a small duty fraction, arrays of particle detectors on ground have a 1 sr field of view and a 100% duty fraction. On the other hand, particle detector arrays have a much higher energy threshold and an inferior hadron rejection as compared to Cherenkov telescopes. Low threshold particle detector arrays would have potential advantages over Cherenkov telescopes in the search for episodic or unexpected sources of gamma rays in the multi-TeV energy range. Ways to improve the threshold and hadron rejection of arrays are shown, based on existing technology for the timing method (with scintillator or water Cherenkov counters) and the tracking method (with tracking detectors). The performance that could be achieved is shown by examples for both methods. At mountain altitude (about 4000 m or above) an energy threshold close to 1 TeV could be achieved. For any significant reduction of the hadronic background by selecting muon-poor showers a muon detection area of at least 1000 m² is required, even for a compact array.     

Wide angle air Cerenkov detectors

For a number of important questions in VHE/UHE cosmic ray physics wide angle air Cerenkov detectors offer superior performance compared to scintillator arrays or air Cerenkov telescopes. On hand of the HEGRA air Cerenkov detector AIROBICC the general principle and performance will be discussed. Ideas and prospects for a detector with an energy threshold around 1 to 3 TeV will be presented.     

Infrared detection,review of existing and future devices

I present the current status of arrays of detectors operating in the 1–200 micron range, restricted to mature devices, and two recent concepts of infrared detection which could lead to future developments.     

GCr15钢离子注入表面改性研究

对航空轴承用钢ＧＣｒ１５进行了硼离子、氮离子及其复合注入试验。利用扫描电镜和Ｘ射线衍射仪对注入层的组织结构进行了分析，并测试了注入层的硬度、耐磨性、耐蚀性。结果表明：ＧＣｒ１５离子注入层形成了多种弥散相和非晶相，表层的残余奥氏体含量也有所减少。表层的硬度、耐磨性以及耐蚀性经离子注入后明显增加。     

Residual Stress Measurement for Ion-implanted NiTi Alloy by Using Moiré Interferometry and Hole-drilling Combined Method

Residual stresses in ion-implanted NiTi alloy are measured by a combined method of Moiré interferometry and hole-drilling. Oxygen ions are implanted into the NiTi alloy under a voltage of 30 kV by a dose of 1.0×1017 ions/cm2 for one hour. Subsequently, in order to avoid dimensional error, a hole is drilled exactly in the center of the sample. The distribution of residual stresses around the hole is measured. It is indicated that the method which combines the Moiré interferometry with hole-drilling is able to be used to measure residual stresses produced by ion implantation.     

轴承钢等离子体基离子注碳复合改性层化学结构的研究

通过激光Ｒａｍａｎ光谱、Ｘ射线光电子谱以及电阻和显微硬度的测试，研究了ＧＣｒ１５钢及镀钛ＧＣｒ１５钢试样经乙等离子基离子注入所得表面改性层的化学结构。     

Privacy algorithm for cylindrical holographic weapons surveillancesystem

A novel personnel surveillance system has been developed to detect and identify threatening objects, which are undetectable by metal detectors, concealed on the human body. This new system can detect threats which are fabricated with plastic, liquid, metal, or ceramic. It uses millimeter-wave array technology and a cylindrical holographic imaging algorithm to provide full-body, 360-degree coverage of a person in near real-time. This system is ideally suited for mass transportation centers such as airport checkpoints that require high throughput rates and full coverage. Research and development efforts are underway to produce a privacy algorithm that removes the human features from the images while identifying the potential threats. This algorithm locates and segments the threats and places them on a wire-frame humanoid representation. The research areas for this algorithm development include artificial neural networks, image processing, edge detection, and dielectric measurements. This system is operational and results from this test and the privacy algorithm will be discussed in this paper     

离子注入抑制摩擦温升的研究

 离子注入抑制摩擦表面的温升,是减少粘着磨损、提高摩擦副耐磨性的新途径。本文采用离子注入技术抑制航空柱塞泵配流副试件摩擦表面的温升,获得显著的效果。当逐级改变负载时,离子注入试件摩擦表面的温度平均下降３５℃；当逐级改变润滑油流率时,试件表面温度平均下降４６℃。并初步探讨了离子注入抑制摩擦温升的机理。     

离子注入提高铜合金耐磨性的初步研究

 本文对ZQSn10-2-3锡青铜表面状态为镀银和未镀银的两种样品,分别采用N₂⁺离子注入及（Ag+N₂⁺）离子束混合技术,进行表面改性,提高其耐磨性。并且用背散射装置、离子探针和扫描电镜对离子注入层进行了测试与分析。试验结果表明,离子注入及离子束混合样品,抗磨损能刀明显提高。     

Two-Stage CFAR Detectors for Multiple-Range-Bin Radars

Two-stage detectors using generalized sign and four-level conditional statistics for signal detection in multiple-range-bin radars are described. The resulting detectors are of constant false-alarm rate (CFAR). Performances are evaluated and compared with singlestage versions. If the a priori probability of either the no-target case or the target-presence case is large (close to 1), a two-stage test can be designed to have the advantage of reducing the average number of samples required without sacrificing detection probability. With the proper choices of parameters, significant improvement in the efficiency can be achieved. Asymptotic relative efficiency of two-stage detectors with respect to single-stage detectors is derived and some numerical results are evaluated.     

Detection of Target Maneuver Onset

A classical maneuvering target tracking (MTT) problem (detection of the onset of a target maneuver) is presented in two parts. The first part reviews most traditional maneuver onset detectors and presents results from a comprehensive simulation study and comparison of their performance. Six algorithms for maneuver onset detection are examined: measurement residual chi-square, input estimate chi-square, input estimate significance test, generalized likelihood ratio (GLR), cumulative sum, and marginalized likelihood ratio (MLR) detectors. The second part proposes two novel maneuver onset detectors based on sequential statistical tests. Cumulative sums (CUSUM) type and Shiryayev sequential probability ratio (SSPRT) maneuver onset detectors are developed by using a likelihood marginalization technique to cope with the difficulty that the target maneuver accelerations are unknown. The proposed technique gives explicit solutions for Gaussian-mixture prior distributions, and can be applied to arbitrary prior distributions through Gaussian-mixture approximations. The approach essentially utilizes a~priori information about the maneuver accelerations in typical tracking engagements and thus allows to improve detection performance as compared with traditional maneuver detectors. Simulation results demonstrating the improved capabilities of the proposed onset maneuver detectors are presented.     

Design of nonparametric truncated sequential detectors withparallel linear boundaries

A design method is proposed for a class of nonparametric truncated sequential detectors. These detectors test nonparametric statistics against two parallel linear boundaries with an abrupt truncation at some sample size. The proposed method obtains the asymptotic relative efficiencies (ARE) of these tests with respect to their corresponding fixed-sample-size (FSS) tests in terms of some parameters of the tests. There parameters are then chosen to optimize the ARE. This (asymptotically) optimal set of parameters is used to design the thresholds of the sequential tests. Numerical results are obtained and design examples are presented, using the sum of the signs of the observations as the test statistic. The method can be used for nonparametric sequential detectors and for robust and parametric sequential detectors as well     

On cross-ambiguity properties of Welch-Costas arrays

We discuss cross-ambiguity properties of a specific family of Costas arrays called Welch-Costas (W-C) arrays. These properties are of interest in multiuser radar and sonar system, especially since Costas arrays are known to possess ideal auto-ambiguity functions. The theory of W-C arrays is reviewed. It is then proved that only pairs of W-C arrays can have at most two hits in their cross-ambiguity function (best possible case). The maximum number of hits in the cross-ambiguity functions of a family of W-C arrays is shown to be a function of the number of W-C arrays in the family. The upper bound on the number of hits in the cross ambiguity functions for a family of W-C arrays is also derived. Specific examples of how reducing the number of W-C arrays improves the cross-ambiguity properties are given for various types of prime numbers     

湿热环境下K-cor夹层复合材料的力学性能

K-cor夹层结构是应用Z-pin技术增强的一种新型高性能夹层结构,本文研究了Z-pin不同植入密度对K-cor夹层结构试样吸湿特性的影响规律,在此基础上对不同Z-pin植入参数对试样湿热前后三点弯曲性能和压缩性能的影响规律进行了深入研究。研究结果表明：夹层结构中Z-pin的植入能提高试样的尺寸稳定性,且不会对其吸湿率造成明显影响;Z-pin植入密度的增加能明显提高湿热前后试样三点弯曲强度和压缩强度,且具有较高的强度保持率,Z-pin密度为12 mm×12 mm的K-cor夹层结构湿热处理试样的三点弯曲强度比未湿热处理空白试样的要高11.1%,8 mm×8 mm湿热处理K-cor试样的芯部压缩强度比未湿热处理空白夹层结构试样要高17.5%,体现出K-cor夹层结构优异的抗湿热性能;而Z-pin植入角度的减小能明显提高试样湿热处理前后的压缩强度,0°植入K-cor试样湿热处理后的芯部压缩强度与40°植入K-cor试样未湿热处理的基本相同,但植入角度对三点弯曲强度影响较小。     

人工免疫木马检测中动态克隆选择算法的改进

针对人工免疫木马检测中检测器的冗余,检测过程中成熟检测器和记忆检测器在检测到自我抗原或年龄过大时,被直接删除造成的非我信息资源丢弃等问题,引入限次变异对检测器的生成进行改进,提出将随机生成的检测器在自我耐受后,再与已有合格检测器匹配,对与已有合格检测器匹配的检测器进行限次变异;而检测到自我抗原或年龄过大的检测器同样进行限次变异的方法。实验结果表明,这种方法能准确而快速地检测已知和未知木马。     

Product Device Analysis for Radar Applications

By applying the theory of two-dimensional Fourier transforms to the response of a product device, results are developed that may be applied to tracking radar range gates, phase detectors, and angle-error detectors. These responses are general in that noises that are present can be nonstationary with arbitrary power spectrum while the radar signal, a pulse stream, can have any envelope shape.     

A new clutter rejection method using a robust polarimetricCFAR-detector

Two methods for constructing robust polarimetric constant-false-alarm-rate (CFAR) detectors that use elements of the scattering matrix are discussed. Both methods use robust estimators to recognize outliers and exclude them from further calculations. The first method weighs each sample of the surrounding vectors, and vectors that appear to be outliers are weighted with lower values than the others. The second method uses cluster algorithms to arrange the data in different clusters; some clusters contain the outliers, and others contain observations assumed to come from the main body of the data. The detectors are intended to be used in multitarget and nonhomogeneous-clutter environments     

Modified Savage and Modified Rank Squared Nonparametric Detectors

A modified form of the basic Savage statistic is considered and the performance of a modified Savage (MS) nonparametric detector using this modified statistic is derived. Also, a detector using a modified rank squared statistic (MRS) is introduced. The asymptotic relative efficiency (ARE) of the detectors is determined for chisquare, Rician, and log-normal signal fluctuations when the background noise is assumed Gaussian. The ARE performance of the generalized sign (GS) and Mann-Whitney (MW) detectors is also determined for these families of fluctuations. The ARE performance of the various detectors is then compared, and the results of a computer simulation are presented in which, for a finite number of samples, the performance of the modified detectors is compared with the performance of the GS and MW detectors. It is shown that when using a large number of reference noise samples, the ARE of the GS and MW detectors, the MRS and RS detectors, and the MS and Savage detectors are 0.75, 0.868, and 1, respectively. It is also shown that when using a finite number of reference noise samples the MS and MRS detectors can give a superior performance to that obtained with the MW detector, and that this is particularly true in the cases in which the degree of signal fluctuation is high.     

基于免疫理论的航空发动机磨损故障智能诊断

针对航空发动机磨损故障诊断技术智能化、精确化的发展要求,以传统油液监测技术为基础,结合人工免疫系统(AIS)具有的自适应特性、学习记忆特性及识别特性等优点,提出了一种航空发动机磨损故障的智能诊断方法。该方法首先利用人工免疫理论的反面选择原理生成检测器,优化后的检测器生成算法提高了初始检测器的代表性及覆盖性;然后利用故障样本训练出成熟的检测器,使航空发动机典型的磨损状态信息存储在检测器中,实现对故障模式的有效学习和记忆;最后通过检测器的激活发现航空发动机的磨损故障。对油样数据的实例分析结果表明,该方法对航空发动机磨损故障具有较强的识别能力,对磨损状态有很好的监测效果。     

Cross-correlation properties of algebraically constructed Costasarrays

The problem of determining the cross-correlation properties of signals based on algebraically constructed Costas arrays is addressed by examining the discrete cross-correlation of the algebraically constructed Costas arrays for a given construction and dimension. Finding two arrays that minimally correlate implies that the signals based on these arrays also minimally correlate. The properties of finite fields are reviewed, and the major algebraic constructions for Costas arrays are presented, i.e. the Welch construction and the Golomb construction. The discrete cross-correlation properties of the Costas arrays are derived for arrays of the same dimension derived from the same construction. The use of Costas arrays in the signal design problem is discussed, and examples are given to show the cross-correlation of the signals based on the algebraically constructed arrays