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1.
介绍了近几年国外参量阵技术在浅海探测声纳、吊放声纳、鱼雷自导声纳、浅海水声通讯等方面的应用进展情况。针对频率为30kHz的线性小目标探测声纳,对原频90kHz、差频30kHz的非线性参量阵进行了性能估算,结果表明,参量阵声纳在高混响背景下探测小目标的性能优于线性声纳。文章还分析了参量阵声纳的新应用所面临的一些技术难点,给出了一种相对简单的宽带参量阵的实现方法。  相似文献   

2.
岳雷  姜春华 《声学技术》2016,35(4):325-330
为研究和分析用仿生信号及处理方法探测沉底小目标的可行性及探测性能,分别从时域频域波形、模糊度函数、抗混响性能方面分析了仿海豚声呐信号,并用计算机仿真了复杂背景下沉底小目标的探测。理论分析和仿真结果表明:在几种仿海豚声呐信号中,频率重叠较多的信号混响抑制效果最好;仿生探测方法的性能比标准声呐探测方法有了明显的提高。仿生信号及探测方法可作为一种新型的沉底小目标探测信号及处理方法。  相似文献   

3.
郭新毅  马力  吴国清 《声学技术》2007,26(5):781-786
根据地声界面波的相关理论,采用时域有限差分法建立浅海沉积层中界面波传播模型。以沉积层中掩埋小目标为例,计算界面波对空腔掩埋物和实心掩埋物的不同作用结果。根据运动方程和应力应变关系采用中心差分网格建立声场的有限差分模型,计算了声场瞬态情况和质点振动的时间序列结果,从不同角度比较分析了地声界面波对掩埋目标的作用。根据浅海沉积层的性质计算了界面波的传播损失和对掩埋物体的目标强度,由于界面波传播衰减主要由沉积层的能量耗散引起,其规律接近横波的传播衰减,在高频情况下界面波在沉积层中传播的距离不远。文章试图建立一种对浅海沉积层中掩埋小尺度目标的探测新方法。通过一些典型模型的分析,从理论角度证明地声界面波对目标探测的可行性。  相似文献   

4.
陈强  田杰  刘维  黄海宁  张春华 《声学技术》2013,32(4):273-276
随着成像声纳技术的发展,声纳图像的目标检测与识别逐渐成为数字图像处理领域的一个重要研究课题。合成孔径声纳图像含有丰富的纹理特征,而灰度共生矩阵具有丰富的特征参数,可以从不同的角度对纹理进行细致刻画。采用灰度共生矩阵可以描述合成孔径声纳图像纹理方面的特征,通过计算灰度共生矩阵在方位向和距离向的能量、相关性、对比度和熵值,并构造特征向量,可以对合成孔径声纳图像中的目标进行准确检测。从实验结果可以看出,基于纹理信息可以准确实现合成孔径声纳图像的目标检测。  相似文献   

5.
提出了一个新的水下声视觉图像预处理、分割和目标跟踪的处理系统框架.采用该系统框架,设计了一个基于前视声纳的智能水下机器人(AUV)声视觉目标探测跟踪系统,并描述了该系统的软、硬件体系结构.针对水下声视觉图像特点,分析了声纳图像的预处理方法,探讨了图像中特征信息的选取,构造了基于不变矩的仿射变换不变量,提出了基于组合特征...  相似文献   

6.
张宝华  赵梅 《声学技术》2013,32(1):24-28
在水声研究和海洋工程中,广泛地需要测量海水声速。纵观水声技术的发展历史,声速及其测量方法和手段一直是水声研究的基本问题。从水下声传播速度的物理特性出发,介绍了典型海洋声速剖面的特征,以声速剖面对声传播的影响为关注对象,示例说明了其对声纳最佳探测深度及声纳探测距离的影响,以及声速测量在大洋测温中的应用。在声速剖面测量方法方面,介绍总结了国内外的声速测量设备的原理、技术发展趋势以及主要产品。最后给出了海洋声速剖面测量的发展展望。  相似文献   

7.
提出了一个新的水下声视觉图像预处理、分割和目标跟踪的处理系统框架.采用该系统框架,设计了一个基于前视声纳的智能水下机器人(AUV)声视觉目标探测跟踪系统,并描述了该系统的软、硬件体系结构.针对水下声视觉图像特点,分析了声纳图像的预处理方法,探讨了图像中特征信息的选取,构造了基于不变矩的仿射变换不变量,提出了基于组合特征的粒子权重分配方法,阐述了改进后的高斯粒子滤波( GPF)跟踪实现过程.海上实验验证了所提方法的有效性,证明所构建的探测跟踪系统具有较高的准确性和鲁棒性.  相似文献   

8.
多波束图像声纳广泛应用于水下工程实施、浅海地貌测绘、蛙人和水雷等水下小目标的探测识别,高频弧形换能器是多波束图像声纳的重要组成部分,用于发射高频宽波束声波.通过理论公式计算了宽波束高频弧形换能器的指向性图,分析了指向性特征:主波束内存在连续的震荡起伏,震荡幅度由中心向两侧逐渐增大,在波束边缘处出现最大值,波束中心幅值比最大值减小1~2 dB左右.采用1-3型压电复合材料,研制了一款宽波束发射的高频弧形换能器,换能器谐振频率为440 kHz,最大发送电压响应为162 dB,-5 dB水平开角为107o,-3 dB垂直开角为26o,可应用于多波束图像声纳.  相似文献   

9.
陈敬军  傅寅锋 《声学技术》2012,31(2):147-151
目标识别是声纳的主要功能之一,其性能包括识别正确率、泛化能力和识别距离。由于数据样本的保密特性,声纳目标识别系统设计有其自身特色。在设计过程中,应首先降低对数据样本的依赖,把目标辐射噪声的机理分析、组成、运动规律等知识巧妙地运用到系统设计中;其次还应尽可能提高泛化率,以提高声纳目标识别系统对未见过的样本的正确识别能力。讨论了声纳目标识别流程、声纳目标识别系统的设计方法;在声纳目标识别系统的性能评估中,给出了目标识别距离的估算方法。  相似文献   

10.
被动声纳目标识别技术的现状与发展   总被引:6,自引:3,他引:6       下载免费PDF全文
丁玉薇 《声学技术》2004,23(4):253-257,260
在现代被动声纳系统中,水下目标的自动识别是关键技术之一。文章对被动声纳目标识别的特征提取、特征选择和分类器设计方面进行了回顾。对LOFAR,DEMON和小波变换等特征提取技术进行了讨论,分析了特征优化的重要性和专家系统和神经网络等分类器的优缺点,并简要分析了该领域的过去、现在和未来。  相似文献   

11.
真空混合漏孔示漏气体的延迟和保持特性研究   总被引:2,自引:1,他引:1  
真空混合漏孔 ,如漏孔通道内含有空腔、毛细管道等 ,示漏气体除存在超长反应时间外 ,还存在超长的延迟时间和保持时间。只有经该延迟时间后 ,检漏仪才能探得信号。为满足真空元件在生产中的快速检漏的要求 ,又避免常规质谱检漏法漏检混合漏孔的可能性 ,在真空室内对检漏元件集体充氦 ,然后在保持期内逐个检测氦气浓度来判断有无混合漏孔 ;也可用质谱计比较残余气质谱图中空气成分来确定  相似文献   

12.
Wu Z  Wang H  Guo M  Tang LJ  Yu RQ  Jiang JH 《Analytical chemistry》2011,83(8):3104-3111
Assays of small molecule-protein interactions are of tremendous importance in chemical genetics, molecular diagnostics, and drug development. This work reports a new finding of generalized terminal protection that small molecule-DNA chimeras are protected from degradation by various DNA exonucleases, when the small molecule moieties are bound to their protein targets. This generalization converts small molecule-protein interaction assays into the detection of DNA of various structures, affording a useful mechanism for the analytics of small molecules. On the basis of this mechanism, a label-free biosensor strategy has been developed for a homogeneous assay of protein-small molecule interactions based on the fluorescence staining detection. Also, a label-free SNP genotyping technique is proposed based on polymerase extension of a single nucleotide with a small molecule label. The developed techniques are demonstrated using a model protein-small molecule system of biotin/streptavidin and a model SNP system of human β-globin gene around the position of codon 39. The results revealed that the protein-small molecule interaction assay strategy shows dynamic responses in the concentration range from 0.5 to 100 nM with a detection limit of 0.1 nM, and the SNP typing technique gives dynamic responses in the concentration range from 0.1 to 200 nM with a detection limit of 0.02 nM. Besides desirable sensitivity, the developed strategies also offer high selectivity, excellent reproducibility, low cost, and simplified operations, implying that these techniques may hold considerable potential for molecular diagnostics and genomic research.  相似文献   

13.
综述了国内外拆除爆破发展和研究现状,并提出今后发展趋势和免于解决的问题。  相似文献   

14.
A High-Sensitivity Narrow-Band Time-Domain Reflectometer   总被引:1,自引:0,他引:1  
Time-domain reflectometer (TDR) techniques have been used to test transmission line systems for over fifteen years. The technique described in this paper is an extension to present-day techniques and is designed particularly to detect small changes in the reflection coefficient of distributed systems versus time. The instrument uses some of the techniques of narrow-band TDR to provide a waveform, related to the distributed reflection coefficient of the system under test, to a small computer. The computer can then perform any of a number of manipulations to the waveform, depending on the wishes of the operator. One particular program produces a waveform profile on a storage oscilloscope which displays small changes in the distributed reflection coefficient with time. This capability of being able to display very small changes in reflection coefficients has resulted in the development of an obstacle detection scheme using so called "leaky" coaxial cable to detect objects at some distance from the cable.  相似文献   

15.
《Advanced Powder Technology》2019,30(9):1989-1993
Determination of liberation spectrums by using MLA and QEMSCAN techniques require polished sections and fine particles. These techniques cannot be performed in-situ and for coarse particles. Thus, the focus of this technical note is to investigate whether the image analysis method can be used for the determination of liberation spectrum for coarse particles. Two methods were used to determine the liberation spectrum. In the first method, the liberation spectrum was obtained using the small and large diameter of particles. In the second method, the liberation spectrum was determined using the small and large diameter of particles as well as the shape correction diameter. The results showed that the image analysis can be used to successfully determine the liberation spectrum. The composition of composite particles was significantly improved when the stereological correction was used i.e. the square root of the mean square error for the particle composition using the method 1 was 1.25% while that using the method 2 was 0.60%. The proposed method might be used for the determination of liberation spectrum of high-grade real coarse particles. However, this requires a significant amount of future work.  相似文献   

16.
针对水性油墨黏度测量方法存在操作复杂、主观性强等问题,利用可见/近红外光谱分析技术结合化学计量学方法,建立水性油墨黏度预测模型,实现水性油墨黏度的快速无损检测。首先,利用微型光纤光谱仪采集水性油墨样本的反射光谱;再通过比较不同预处理方法对原始光谱数据的预处理效果,分别基于原始全光谱及预处理后的光谱数据构建水性油墨黏度的偏最小二乘回归(PLSR)和主成分回归(PCR)预测模型;最后,将预处理后的光谱数据采用连续投影算法(SPA)和竞争性自适应重加权算法(CARS)提取特征波长,并基于特征波长的光谱数据建立水性油墨黏度的PLS预测回归模型。结果表明,采用SPA算法从全光谱中只提取了4个特征波长,不仅显著简化了模型,提升了模型的运算效率,建立的SNV-SPA-PLS模型还具有最佳的预测性能(Rp2=0.9992, RMSEP=0.0732)。该研究结果表明应用光谱分析技术实现对水性油墨黏度检测是有效可行的,为进一步通过光谱分析技术进行水性油墨在线黏度检测提供了新方法,为提高印刷品质量稳定性提供了技术基础。  相似文献   

17.
This paper presents a practical methodology for the routine analysis of VLSI infant mortality data. Device families are modelled using established graphical parameter estimation techniques, and the model parameters are applied to individual device types within the family. Burn-in requirements are calculated to achieve a desired early life reliability level. A technical summary of the methods is presented, and a small data set is analysed as an example. The analysis results from three large device families are also presented.  相似文献   

18.
Image retrieval for food ingredients is important work, tremendously tiring, uninteresting, and expensive. Computer vision systems have extraordinary advancements in image retrieval with CNNs skills. But it is not feasible for small-size food datasets using convolutional neural networks directly. In this study, a novel image retrieval approach is presented for small and medium-scale food datasets, which both augments images utilizing image transformation techniques to enlarge the size of datasets, and promotes the average accuracy of food recognition with state-of-the-art deep learning technologies. First, typical image transformation techniques are used to augment food images. Then transfer learning technology based on deep learning is applied to extract image features. Finally, a food recognition algorithm is leveraged on extracted deep-feature vectors. The presented image-retrieval architecture is analyzed based on a small-scale food dataset which is composed of forty-one categories of food ingredients and one hundred pictures for each category. Extensive experimental results demonstrate the advantages of image-augmentation architecture for small and medium datasets using deep learning. The novel approach combines image augmentation, ResNet feature vectors, and SMO classification, and shows its superiority for food detection of small/medium-scale datasets with comprehensive experiments.  相似文献   

19.
This paper presents technical developments for the detection of formaldehyde (CH2O) using laser-induced fluorescence. The easily accessible third harmonic of the Nd:YAG laser at 355 nm was used for excitation of formaldehyde. In order to investigate potential background fluorescence, e.g., from large molecules such as polyaromatic hydrocarbons, special attention was paid to investigating the possibility of scanning the wavelength of a single-mode Nd:YAG laser under the gain profile, approximately 3 cm(-1), on and off resonance. Furthermore, a technique for simultaneous detection of formaldehyde and OH using one laser system is presented. The single-mode Nd: YAG laser at 355 nm in combination with an optical parametric oscillator (OPO) laser tuned to 283 nm was used for simultaneous two-dimensional imaging of both species using one charge-coupled device (CCD) detector equipped with a dual filter image separator. The techniques are demonstrated with measurements in laboratory flames and the combined measurements are also demonstrated in an engine.  相似文献   

20.
基于时域振动响应的结构损伤检测方法因其便于实现在线监测受到了越来越多的关注。该文回顾了两种利用时域响应相关函数建立的结构特征向量(即内积向量及互相关函数幅值向量)及其对应的损伤检测方法。为了从时域响应相关函数中提取更多的结构健康信息,通过利用不同的结构响应组合,将上述两种结构特征向量扩展到了多种结构特征向量,并进一步采用数据融合理论,提出了检测精度更高的结构损伤检测方法。针对8层框架结构损伤检测的试验研究结果表明,该文方法可以对框架结构上的微小损伤进行定位。  相似文献   

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