基于小信号电桥法的换能器测试方法

针对目前测深仪、声呐及多普勒计程仪保障维修过程中对换能器技术状态鉴定所面临的困境,研制了基于小信号电桥法的换能器测量仪器,通过单片机、信号发生器、电桥电路法、电压测量法测量换能器的动态等效电容、等效电阻、谐振频率等技术指标,并通过软、硬件予以实现,经实践检验,有效地提高了对换能器技术状态鉴定的效率。在日常修理中有很强的实用性。该方法已在回声测深仪修理调试检测设备中得到应用。     

多频回声测深仪在黄河小浪底库区水深测量的应用

随着科学技术的不断发展和提高,多频回声测深仪在水深测量、航道勘测等各个领域得到了广泛的应用。本文从多频回声测深仪的工作原理出发,分析了多频回声测深仪的工作特点、影响因素以及多频回声测深仪的具体应用,为使用多频回声测深仪进行测量提供一定帮助。     

测深仪在城市河道测绘中的应用

混本文首先通过对测深仪工作原理的分析,进行了测深仪在城市河道测绘中的测绘技术要求的分析,并且分析了测深中的关键误差,为城市河道的测绘工作提供了支持。     

测深仪在城市河道测绘中的应用

本文首先通过对测深仪工作原理的分析,进行了测深仪在城市河道测绘中的测绘技术要求的分析,并且分析了测深中的关键误差,为城市河道的测绘工作提供了支持。     

条带测深仪的信号特征及其动态范围压缩

条带测深仪又称多波束地形测绘声呐。９０年代以来，由于海洋测绘事业的需要，我国已向国外引进并开始自行研制这类声呐。本文首先介绍了它的基本工作原理。第２节分析进入接收机的海底反向散射信号的特征，说明了这一信号有很大的幅值动态范围的原因。第３节讨论了两种不同性质动态范围压缩方法，并给出了实现的硬件框图，软件流程图和部分试验结果。     

新型数字化测深仪设计

本文介绍了某新型数字化回声测深仪的研制，包括系统的组成和软硬件设计等内容。     

GPS卫星可见性预测与接收机的快速定位

为了解决GPS接收机快速捕星问题,提高接收机定位速度,利用历书信息进行GPS卫星预报,提出了一种GPS卫星可见性预测的改进算法.在星历信息基础之上,用此算法对卫星的可见性及概略多普勒频移进行预测,并在GPS信号模拟器和GPS接收机组建的实验平台上,利用此种方法进行捕星定位实验.实验结果显示:该方法定位时间为原定位时间的39.5%.     

船用测深仪的原理与安装使用

船用回声式测深仪的工作原理、安装要求，故障与检修。     

高温超导磁体的一种失超判别方法

高温超导同步电动机转子上的Bi2223／Ag带高温超导磁体，其结构特殊，且工作在旋转状态，必然给其失超信号的检测提出新的问题。试验表明，为快速、准确检测到失超信号，仅用经验失超判据Ec=1μV／cm是不够的。为此，通过对试验数据的分析提出dv／dt失超判别方法。此方法从磁体的电压一电流特性入手，根据每个励磁阶段的电压变化情况，设置相应的电压变化率的阈值。     

温度变化对压力式测深仪测量结果的影响初探

提出了日常校准工作中两台海洋压力式测深仪在实验室校准后应用于现场测量中所得测量差异过大的现象,为了探寻其产生原因,在实验室条件下设计了一系列校准和测量实验,最终确定了测量差异是由于压力传感器受温度变化导致的。实验人员通过复现现场测量环境温度,对仪器进行了重新校准,利用新参数修正现场测量值,结果表明两台测深仪修正后的测量结果一致性良好。通过对数据的分析,初步发现了温度变化对海水压力测量仪器测量结果的影响规律。     

基于振动信号的汽车纵梁腹面冲漏孔智能在线检测技术

目的 针对传统汽车纵梁腹面冲孔过程中产生的加工孔漏冲现象,提出一种基于振动信号的智能漏孔在线检测技术。方法 在纵梁冲孔设备上合理布置加速度传感器,对采集的振动信号进行时域和频域特性分析,构建归一化的压缩混合域特性指标矩阵,提取正常冲孔和漏冲信号的可靠评价指标,并进一步建立漏孔的智能在线检测方案。结果 在时域上,漏冲信号的平均值和有效值要比正常冲信号的低,同时具有明显冲击峰的波峰个数要少;在频域上,漏冲信号的频率幅值最大值、频率幅值平均值以及能量要比正常冲信号的低,但是其变异系数要比正常冲信号的高。结论 提出了一种智能漏孔检测方案,可以通过对采集的信号进行预判断、处理、特征提取、检测判断等,分离出漏冲信号和正常冲信号。     

基于CPS信号评价内燃机怠速燃烧稳定性的方法

提出利用CPS信号计算曲轴角加速度参数评价内燃机怠速燃烧稳定性的方法。识别CPS信号的缺齿位置并对缺齿处的零点进行补充,利用CPS信号计算曲轴的角速度和角加速度;选择小波阈值去噪方法对角速度和角加速度进行滤波;分析角加速度参数和相应气缸压力参数之间的线性相关性。角加速度参数和相应的气缸压参数之间为高度正相关,说明应用CPS信号计算角加速度参数评价内燃机怠速燃烧稳定性的方法是可行的。     

A programmable self-adaptive digital frequency multiplier

Existing self-adaptive frequency multipliers work well if the master clock frequency is an integral multiple of the input signal frequency; otherwise they lose an output pulse after a certain interval of time. The frequency of this missing pulse could be as high as half of the input frequency. Since existing self-adaptive frequency multipliers are not programmable, the multiplication factor can not be changed without doing some major changes in the hardware. The reason for missing an output pulse is explained, and design and implementation of a programmable self-adaptive digital frequency multiplier, that does not have this missing pulse problem are presented. The errors associated with the multiplier are discussed     

阵元失效对克罗内克积波束形成性能的影响

对于一类规则阵型,可以引入克罗内克积提高最小方差无失真响应波束形成器的鲁棒性,同时降低其运算复杂度;然而,对于阵元数较多的规则阵列,阵元失效的可能性大幅增加,当某些阵元失效时,规则阵列不满足克罗内克分解。针对常见阵元失效问题,文章研究了阵元失效的三种情况对最小方差无失真响应波束形成器与克罗内克积自适应波束形成的性能影响。仿真与实验结果证明,信号完全缺失的通道对自适应波束形成器的影响最大,信号重复的通道对自适应波束形成器的影响最小。文章据此提出了一种低复杂度的信号恢复方法,通过使用相邻通道的信号代替信号缺失通道,提升阵元失效情况下的波束形成性能。     

A comparative evaluation of several algorithms for phase aberrationcorrection

A common framework is presented to classify several phase correction techniques. A subset of these techniques are evaluated through simulations which utilize 2-D phase aberration profiles measured in the breast. The techniques are compared based on their ability to reduce phase errors, stability, and sensitivity to noise and missing elements in the transducer array. Significant differences are observed in these measures of performance when the size and location of the aperture area used to generate a phase reference signal are varied. Techniques that utilize a small correction reference region are more susceptible to noise and missing elements than techniques which use larger reference regions. The algorithms encounter problems in 2-D phase correction when making the transition from one row to the next, due to the low interelement correlation at the transition points. It is shown that the magnitude of the interelement correlation is the key parameter governing phase correction performance     

红外测角仪抗红外干扰的信息处理方法

简要介绍了反坦克导弹红外测角仪的信息处理系统组成原理，讨论了红外测角仪抗红外干扰的信息处理方法，导弹目标信号的确定要通过真假红外信号的模式识别和航迹判别处理等才能最终确定，同时对由于大气红外衰减造成的红外信号闪烁以及其它干扰造成的导弹目标丢失情况，设计了信号数据溢出处理模块。这些信息处理方法使红外测角仪的抗红外干扰能力明显提高。试验表明，当坦克目标上有一个探照灯时，红外测角仪能正常工作，当横向偏离坦克目标或弹道10m以外有2个红外干扰时，红外测角仪也能正常工作。     

多线程VC++和Matlab混编在信号采集和处理中的应用

在信号采集和处理过程中,Visual C 存在数据处理和结果显示方面的不足,Matlab存在可视化和数据采集方面的不足,本文在Visual C 环境下调用Matlab Engine函数,有效地解决了这两方面的问题;采用多线程编程技术,同时采集和显示信号,有效地防止了采样过程中的掉点。利用本方法对UA302型采集卡采集到的信号进行处理,得到了满意的结果。     

Direct fast method for time-limited signal reconstruction

We consider reconstruction of signals by a direct method for the solution of the discrete Fourier system. We note that the reconstruction of a time-limited signal can be simply realized by using only either the real part or the imaginary part of the discrete Fourier transform (DFT) matrix. Therefore, based on the study of the special structure of the real and imaginary parts of the discrete Fourier matrix, we propose a fast direct method for the signal reconstruction problem, which utilizes the numerically truncated singular value decomposition. The method enables us to recover the original signal in a stable way from the frequency information, which may be corrupted by noise and/or some missing data. The classical inverse Fourier transform cannot be applied directly in the latter situation. The pivotal point of the reconstruction is the explicit computation of the singular value decomposition of the real part of the DFT for any order. Numerical experiments for 1D and 2D signal reconstruction and image restoration are given.     

Textural singularities in superfluid3He-B

The absorption signal occasionally found missing in the middle of resonance absorption lines in NMR is explained on the basis of a textural singularity of the anisotropy axis in the B phase of ³ He. The singularity combines with the field gradient present to give rise to an asymmetric hole in the signal with a singularity on the high-frequency side. The line shapes and temperature dependence are predicted and agree well with experiment. Spin waves are found to be trapped by the potential well formed by the texture and the field gradient. The frequency intervals predicted for the spin waves also agree well with experiment.Work supported in part by National Science Foundation Grant No. NSF DMR 74-18030.     

Scalable tensor factorizations for incomplete data

The problem of incomplete data - i.e., data with missing or unknown values - in multi-way arrays is ubiquitous in biomedical signal processing, network traffic analysis, bibliometrics, social network analysis, chemometrics, computer vision, communication networks, etc. We consider the problem of how to factorize data sets with missing values with the goal of capturing the underlying latent structure of the data and possibly reconstructing missing values (i.e., tensor completion). We focus on one of the most well-known tensor factorizations that captures multi-linear structure, CANDECOMP/PARAFAC (CP). In the presence of missing data, CP can be formulated as a weighted least squares problem that models only the known entries. We develop an algorithm called CP-WOPT (CP Weighted OPTimization) that uses a first-order optimization approach to solve the weighted least squares problem. Based on extensive numerical experiments, our algorithm is shown to successfully factorize tensors with noise and up to 99% missing data. A unique aspect of our approach is that it scales to sparse large-scale data, e.g., 1000 × 1000 × 1000 with five million known entries (0.5% dense). We further demonstrate the usefulness of CP-WOPT on two real-world applications: a novel EEG (electroencephalogram) application where missing data is frequently encountered due to disconnections of electrodes and the problem of modeling computer network traffic where data may be absent due to the expense of the data collection process.