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水下目标检测与识别是声呐系统的主要任务之一,但就目前而言,由于水下目标检测与识别技术还不够成熟,因而水下目标检测与识别技术也是声呐技术领域最迫切需要解决的难题之一。本文在基于亮点模型的前提下,运用Matlab软件对潜艇、鱼雷和水雷这三种常见水下目标的回声信号进行了模拟与仿真,并对模拟仿真所得到的目标回声信号以及真实实验数据进行了相关处理。研究了目标回声信号的相关特性,总结得出相应的规律与结论,为进而运用到实际的目标识别技术中提供了可能. 相似文献
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针对浅海随机噪声与混响背景下蛙人等弱回波强度、慢速小目标的检测问题,提出一种基于声呐历程累积图像的目标检测方法。首先根据声呐图像时域、空域相关性,采用背景空时归一化处理技术,抑制声呐背景中的静态混响、突发性噪声等强回波干扰。声呐历程累积图像集成了多帧声呐图像的信息,目标回波亮点由于运动连续性形成亮线特征,利用该特征,采用Radon恒虚警率(Radon Constant False Alarm Rate,Radon-CFAR)检测声呐历程累积图像中的目标短时运动轨迹,能够检测到低信噪比的目标。分析了空时归一化处理和检测算法的性能,并通过海试数据验证了该算法的有效性,可以检测到低信噪比的蛙人目标回波。 相似文献
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主动声呐信号处理中一般采用匹配滤波和背景均衡等算法检测回波信号,为提高信号的检测性能,还需利用信号与混响和环境噪声在时间、空间上的统计特征差异。文章在对信号的时、空特征算法进行简单描述的基础上,提出了频率能量统计特征和方位能量统计特征,将两种特征检测器的输出进行融合处理构成时、空联合检测器。仿真和试验数据处理结果证明,此方法可有效提高机动小目标在混响及环境噪声中的检测性能。 相似文献
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探测高速小目标的声纳信号波形设计 总被引:3,自引:0,他引:3
针对用主动声纳探测水下高速运动的小目标存在的主要干扰,海面,海底混响和接收信号的起伏,讨论了宜采用的声纳信号形式,在混响信道中,对高多普勒目标采用加窗的长CW脉冲是合适的,而根据多途信道中回波存在的起伏的特点,需要采用多频脉冲,最后给出了用探测高速小目标的声纳最佳发射信号形式和频率编码方案。 相似文献
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提出了一种基于Gram-Schmidt正变化算法的水下目标回波检测方法.该方法利用Gram—Schmidt正变化算法实现对干扰背景的预白化,通过归一化匹配滤波器可完成对水下目标回渡的检测.对仿真数据和实验数据的处理验证了该方法的有效性. 相似文献
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海洋混响仿真技术研究 总被引:11,自引:0,他引:11
本文研究了海洋混响的仿真实现技术,解决了混响仿真中窄带滤波器设计和混响包络曲线确定等技术难点。用该仿真方法产生的海洋混响的仿真信号无论是在形式上还是在统计特性上都与海洋混响的实测信号和理论分析的结果具有较好的一致性,对近程水下跟踪声探测系统的仿真研究具有重要的意义。 相似文献
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复杂背景下多目标提取的高灵敏度方法 总被引:1,自引:0,他引:1
对电视经纬仪拍摄到的飞行小目标图像进行了归一化高斯模板相关。传统的模板相关方法不能将真假目标集合充分分离,导致真目标的漏检或引入虚假目标。基于模板相关的高斯函数拟合方法(Gaussian Function Fitting Method, GFFM),对模板相关所得到的目标集(含有真目标和假目标)中的每一个元素进行高斯函数拟合,并引入了一个更为灵敏的检验量—高斯函数拟合误差,可以将真假目标集合明显区分开,减小阈值确定的难度。实验表明:当相关系数阈值rth=0.8时,传统模板相关方法漏检率20%,虚警率40%;而GFFM方法则检出了所有真目标,且无虚假目标。 相似文献
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Prof. Dr. D. A. Kouremenos Assist. Prof. Dr. K. A. Antonopoulos 《Acta Mechanica》1989,76(3-4):223-233
Summary The calculation of the normal shock wave of real gases poses serious difficulties either because of the complexity of the
exact thermal and caloric equations of state of the real gas considered, or because of the total lack of these equations.
The present work describes a method for the prediction of the normal shock wave of real gases, which is based on the Redlich-Kwong
generalized equation of state. The method involves iterative solution of the energy conservation equation for one of the state
variables, while all the other variables are calculated explicitly. The method is applicable to real gases for which no detailed
thermodynamic data are available, as the only gas-dependent information required is the values of pressure and temperature
at the critical point and the heat capacity in the ideal gas state (pressure approaching zero). Because of the short computational
time, the method is recommended even in the case of real gases for which the exact thermal and caloric equations of state
are available. Applications have been made in the case of real air, for which exact shock wave values are available for comparison
with the present method. The agreement is very good in a wide range of conditions.
With 3 Figures 相似文献
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高帧频大视场多目标实时检测方法研究 总被引:1,自引:0,他引:1
针对高帧频大视场电视跟踪系统中多目标检测的实际需要研究了一种简单的目标检测方法──自适应邻域均值门限检测方法;通过分析,证明该方法能够在信噪比较低和背景干扰较强的情况下对全视场中多个弱小目标进行实时检测,并建立了该算法的实时处理系统;结果表明该方法是完全可行的。 相似文献
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Real‐time ballistocardiographic artifact reduction using the k‐teager energy operator detector and multi‐channel referenced adaptive noise cancelling 下载免费PDF全文
Xiaotong Wen Mingxuan Kang Li Yao Xiaojie Zhao 《International journal of imaging systems and technology》2016,26(3):209-215
The simultaneous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) recording technique has recently received considerable attention and has been used in many studies on cognition and neurological disease. EEG‐fMRI simultaneous recording has the advantage of enabling the monitoring of brain activity with both high temporal resolution and high spatial resolution in real time. The successful removal of the ballistocardiographic (BCG) artifact from the EEG signal recorded during an MRI is an important prerequisite for real‐time EEG‐fMRI joint analysis. We have developed a new framework dedicated to BCG artifact removal in real‐time. This framework includes a new real‐time R‐peak detection method combining a k‐Teager energy operator, a thresholding detector, and a correlation detector, as well as a real‐time BCG artifact reduction procedure combining average artifact template subtraction and a new multi‐channel referenced adaptive noise cancelling method. Our results demonstrate that this new framework is efficient in the real‐time removal of the BCG artifact. The multi‐channel adaptive noise cancellation (mANC) method performs better than the traditional ANC method in eliminating the BCG residual artifact. In addition, the computational speed of the mANC method fulfills the requirements of real‐time EEG‐fMRI analysis. © 2016 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 26, 209–215, 2016 相似文献
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飞机颤振试飞试验信号的广义时频滤波 总被引:1,自引:0,他引:1
针对飞机颤振试飞试验信号噪声过大的问题,提出了一种广义时频域滤波算法。算法采用分数阶傅里叶变换对线性扫频激励及其响应信号进行广义时频分析,利用该类信号在分数阶傅里叶域内的聚焦特性,有效提取真实响应信号,达到信噪分离的目的。给出了具体的滤波算法,并将其应用于仿真算例和实际试飞数据,结果表明该方法可显著提高信号的信噪比。 相似文献
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用VxD编写Windows95中断处理程序的方法 总被引:4,自引:0,他引:4
Windows95操作系统下的实时控制程序,分得用其孤图形界面等许多特性,但由于系统统一管理资源,利用Windows系统作实时控制的很少见。探讨利用虚拟设备驱动程序(VxD)技术提高Windows中断响应速度的方法,并提供有关测试数据,用此方法可在一定程度上实现了Windows95下的实时控制。 相似文献
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为实现机载合成孔径雷达(Synthetic Aperture Radar,简称SAR)实际回波数据中的运动目标聚焦成像,本文在用前置滤波法检测出运动目标的基础上,提出了利用目标子图像匹配方法来估计动目标的方位向速度,得到相应的运动目标聚焦参考函数,然后对运动目标进行聚焦成像,并给出了利用该方法得到的运动目标聚焦图像.成像结果表明,目标子图像匹配方法对动目标成像是有效的,易于工程实现,有实际应用价值. 相似文献
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A. A. Antanovich G. Ya. Savel'ev M. A. Plotnikov 《Journal of Engineering Physics and Thermophysics》1968,15(2):758-760
An analysis is presented of the contemporary methods of calculating the thermodynamic properties of real gases at pressures up to 12 kbar. We propose a semiempirical method of calculating the parameters of real gases in the range of temperatures from 700 to 1200° K. The method is illustrated with calculations for nitrogen. 相似文献
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In this paper, the limitations and shortcomings of the existing methods for solving fuzzy solid transportation problem are pointed out and to overcome these shortcomings, a new method is proposed for solving fuzzy solid transportation problem. The advantages of the proposed method over the existing methods are discussed. To illustrate the proposed method, an existing fuzzy solid transportation problem is solved. Also, to show the application of the proposed method in real life problems an existing real life fuzzy solid transportation problem is solved by the proposed method. 相似文献