起重机制动器试验台检测系统软件设计

数据的采集和处理是制动器试验台检测系统的关键,是制动器性能试验和质量检测的基础.根据某起重机制动器试验台的特点及检测项目需求,本文设计了基于虚拟仪器技术的起重机制动器试验台检测系统,详细阐述了该系统软件部分的结构、功能及其实现,并对其数据处理方法进行了具体说明.     

Detection Probabilities for Log-Normally Distributed Signals

The amplitude and power of a large family of radio signals are observed to have log-normal probability density functions. Among these are signals propagated through random inhomogeneous media, a notable example being low frequency atmospheric radio noise. Of greater importance are certain radar targets that have been observed to have essentially log-normal density functions. Both ships and space vehicles may fall into this category. Curves of probability of detection vs. signal-to-noise ratio for the case of log-normal signals in Gaussian noise have been computed and are presented in this paper. The curves apply for square-law detection with varying degrees of postdetection linear integration. Both fully correlated and completely uncorrelated fluctuating signals are considered. It is shown that for log-normal signal distributions having large variances, the probability of detection differs significantly from that obtained using curves based on an assumed Rayleigh signal distribution.     

Signal Detection Using Bit-Slice Microprocessors

A bit-slice microprocessor configuration is presented which is applicable to implementation of real-time signal detection algorithms. The general hardware configuration and appropriate software functions are described. General algorithms which are of wide utility in signal detection applications are discussed in the context of the defined hardware configuration. To facilitate the presentation and indicate the practicality of this system configuration, the application of the hardware configuration and software techniques to target detection for passively received signals using multiple receive beams is discussed.     

动态神经网络在液体火箭发动机故障检测与分离中的应用

应用动态神经网络在线辨识方法，提出了一种液体火箭发动机故障实时检测与分离基本系统。检测逻辑通过度量包含发动机故障信息的辨识残差信号实现火箭发动机故障检测，故障分离通过分析辨识误差相关函数的不同空间特征来实现。仿真研究表明动态神经网络可成功地应用于泵压式液体火箭发动机故障检测与分离。     

Filter Selection for Receivers Using Square-Law Detection

A numerical method is described for predicting the detection probability performance of a pulse receiver which uses square-law detection. The method is useful for receivers where the ratio of RF bandwidth to video bandwidth is in the range from 2 to 40; a range where numerical results have previously been hard to obtain. A key feature of the approach is that it takes into account the actual filter transfer functions, pulse envelope shape, and pulse frequency.     

Sidelobe blanking with integration and target fluctuation

In radar systems, sidelobe blanking (SLB) is used to mitigate impulsive interference that enters the radar through sidelobes of the main antenna. SLB employs an auxiliary antenna channel with the output being compared with that of the main antenna channel and a decision is then made as to whether or not to blank the main channel output. SLB performance determination involves the evaluation of several probability functions. Based on the classical Maisel SLB architecture, this work extends previous performance results, in which detection was limited to the case of a single radar pulse with either Marcum or Swerling I target fluctuation. Probability expressions have been generalized to include both an arbitrary number of integrated pulses and target fluctuation models based on the gamma distribution. The Swerling fluctuation models are all special cases of the gamma distribution. Results are derived in terms of two generalized probability functions, one for detection and the other for blanking. With these generalized probability functions, the SLB design and performance results can be determined. Examples are presented and discussed.     

前视探测和多传感器综合视景系统在民机上的应用

简述了前视探测及其视景系统的功能和类别,包括前视探测传感器的类别、视景系统综合方法上的类别。着重介绍了多传感器综合视景系统在民机上的开发应用,列举各种传感器的性能,以及20世纪末欧美国家一些研究试验项目的成果和应用前景。     

Pade approximations of probability density functions

The analysis of radar detection systems often requires extensive knowledge of the special functions of applied mathematics, and their computation. Yet, the moments of the detection random variable are often easily obtained. We demonstrate here how to employ a limited number of exactly specified moments to approximate the probability density and distribution functions of various random variables. The approach is to use the technique of Pade approximations (PA) which creates a pole-zero model of the moment generating function (mgf). This mgf is inverted using residues to obtain the densities     

Optimal Target t Designation Techniques

Studies of signal processing techniques are presented for achieving optimal autonomous acquisition of stationary targets located in a moderately intense nonhomogeneous radar ground clutter background. The process of target acquisition comprises three basic functions: 1) target detection, 2) target selection or designation, and 3) reacquiring the target for tracking. It is the second of these functions, i.e., autonomous designation of a target, that is the subject of this discussion. Theoretical analyses and predictions of the probability of correct target designation for two acquisition search methods are presented and compared with results achieved using real radar imagery.     

Pade approximations to matched-filter amplitude probabilityfunctions: Rayleigh mixtures and multiple observations

Techniques are presented for deriving approximations to the statistical functions that characterize linear sums of matched-filter outputs. They are derived using two techniques: (1) Pade approximations to the multidimensional characteristic function (CF), and (2) discrete Rayleigh mixtures based on an exact or approximate form of the Rayleigh parameter probability density function. The Pade-based approximations are used for modeling the "clutter-only" case and computing detection thresholds, whereas the Rayleigh mixtures are best suited for modeling the "target-plus-clutter" case and computing target detection probabilities     

基于多层激励函数量子神经网络的入侵检测研究

为解决传统入侵检测模型所存在的检测效率低,对未知的入侵行为检测困难等问题,对神经网路隐层激励函数进行了研究,利用多层激励函数的量子神经网络模型进行入侵检测,该量子神经网络借鉴量子理论中量子态叠加的思想,使得隐层神经元能表示更多地状态或量级,从而很好的对入侵类型进行分类,增加隐层神经元的处理速度和检测性能法。实验表明,叠加的每个sigmoid函数较传统的sigmoid函数不仅对已知的入侵具有较好的识别能力,而且能较好的识别未知入侵行为,从而实现入侵检测的智能化。     

Determination of Failure Thresholds in Hybrid Navigation

A systematic approach for the determination of failure thresholds for hybrid navigation systems is described. Cost functions which reflect the importance assigned to the consequences of false and missed alarms are minimized. The false alarm probability is obtained as a function of the threshold magnitude by observing the statistical behavior of the instrument outputs in the normal operating mode. The missed alarm probability is obtained by determining the sensitivity of navigation error performance to instrument error sources. Two cost functions are considered. To illustrate this method, failure detection and identification (FDI) thresholds are determined for the Space Shuttle Approach and Landing Test flight.     

故障检测的智能决策

 根据Schank的动态记忆理论,研究了信息系统的分类,给出了具有智能性质的决策算法。动态系统的故障检测可归结为系统有故障和无故障,由此给出了故障检测的智能决策算法。许多复杂的故障检测算法可归结为简捷的线性函数正、负的判断,因而可有效降低算法的复杂性。实例验证了故障检测的智能决策算法的有效性。     

在轨服务中非合作目标空间圆检测方法研究

为自主完成空间服务任务,需要满足各种功能需求、突破多种关键技术。针对在轨服务中具有圆特征的非合作目标空间圆（星箭对接环、发动机喷管等）,首先分析了非合作目标空间圆检测技术在在轨服务系统中的主要应用;然后提出了一种非合作目标空间圆的检测方法,通过Canny算子检测边缘,并用Freeman链码法对边缘进行提取分类,再利用RED算法进行非合作目标空间圆检测;最后给出仿真结果,在保证检测精度的前提下,较传统的RED算法明显降低了算法的耗时量。     

Generalized input-estimation technique for tracking maneuveringtargets

A new input estimation technique for target tracking problem is proposed. Conventional input estimation techniques assume that the target maneuver level is constant within the detection window, which has been the major drawback of the techniques. The proposed technique is developed to overcome this drawback by modeling the target maneuver as a linear combination of some basic time functions. The resulting algorithm has a generalized formulation including earlier works on input estimation. A detection performance of the proposed algorithm is analyzed by investigating the detection sensitivity according to the selection of maneuver models and other design parameters such as the detection window size, measurement noise level, and sampling step size. A computer simulation study shows that the estimation performance of the proposed algorithm is comparable to Bogler's input estimation method while the computation time is greatly reduced     

复合材料蜂窝板积水的脉冲热像检测的研究

 用数值模拟和实验研究了飞机蜂窝板积水的脉冲热像检测的规律。提出了蜂窝板积水检测的新型三维传热模型;用有限元法分析了近水检测、远水检测和立放检测3种检测模式下信息参数与积水量的关系;用脉冲热像实验验证了近水检测的基本规律。结果表明:在这3种检测模式下,最大温差和最大对比度与积水高度均呈非线性关系,随着积水高度的增加而增大。近水检测灵敏度最高,其次是蜂窝板立放检测,远水检测灵敏度最低。积水和富胶对表面温度的影响趋势一致,利用温差曲线或最大温差信息无法区分积水和富胶状态。根据可检信息参数与积水高度的关系曲线可以反向估计积水高度。这些研究结果为飞机蜂窝板积水的脉冲热像检测及评估提供了技术支持。     

国外机载海面监视雷达发展现状与趋势

首先对目前西方国家装备的较先进的机载海面监视雷达进行了介绍,总结了它们的技术特点。现役机载海面监视雷达具有多功能和多工作模式的特点,除增强了对高海况下的小目标检测能力外,还新增了气象探测、SAR/ISAR和HRRP等先进功能。最后指出了机载海面监视雷达未来发展趋势。     

Analysis of Detection Probability for the Acoustooptic Receiver

A numerical method is described for analyzing the performance of an acoustooptic receiver. The method provides output waveforms, probability density functions for samples of the output, and detection probabilities for output samples. The approach is general in that input pulse envelope shapes, pulse offset frequencies, and output rilter magnitude responses are arbitrary. The basic analysis is also independent of the shape of the optical beam and of the photodiode windows.     

An Algorithm for Tracking a Maneuvering Target in Clutter

We consider the problem of tracking a maneuvering target in clutter. In such an environment, missed detections and false alarms make it impossible to decide, with certainty, the origin of received echoes. Processing radar returns in cluttered environments consists of three functions: 1) target detection and plot formation, 2) plot-to-track association, and 3) track updating. Two inadequacies of the present approaches are 1) Optimization of detection characteristics have not been considered and 2) features that can be used in the plot-to-track correlation process are restricted to a specific class. This paper presents a new approach to overcome these limitations. This approach facilitates tracking of a maneuvering target in clutter and improves tracking performance for weak targets.     

MSK and Offset QPSK Modulation with Bandlimiting Filters

It is considered by some that minimum shift keying (MSK) is spectrally more efficient than quaternary phase-shift keying/offset quadrature phase-shift keying (QPSK/OQPSK). An analytical method is presented here for determining the detection efficiencies of MSK and QPSK/OQPSK when the constant-envelope signal is passed through a set of filters and when the resulting signal is corrupted by Gaussian noise. The detection efficiency of MSK is compared with that of QPSK/OQPSK when a four-pole Butterworth filter is used as a transmit filter and for two different receive filter functions. When the two-sided 3-dB bandwidth of the transmit filter is between approximately 1.00/T and 1.50/T, it is shown that the detection efficiency of MSK is not substantially different from that of QPSK/OQPSK. For more severe bandlimiting of the signal, the performance of MSK is shown to be inferior to that of QPSK/OQPSK. It is, therefore, concluded that MSK does not have significantly better detection efficiency when the effect of bandlimiting filters is taken into account.