Distortion Identification Technique Based on Hilbert-Huang Transform in Video Stabilization

A distortion identification technique is presented based on Hilbert-Huang transform to identify distortion model and distortion frequency of distorted real-world image sequences. The distortion model is identified simply based on Hilbert marginal spectral analysis after empirical mode decomposing. And distortion frequency is identified by analyzing the occurrence frequency of instantaneous frequency components of every intrinsic mode functions. Rational digital frequency filter with suitable cutoff frequency is designed to remove undesired fluctuations based on identification results. Experimental results show that this technique can identify distortion model and distortion frequency of displacement sequence accurately and efficiently. Based on identification results, distorted image sequence can be stabilized effectively.

FEM Simulation of Distortion and Residual Stress Generated by High Energy Beam Welding with Considering Phase Transformation

A series of experiments was carried out so as to elucidate the effect of the phase transformation in the cooling process on welding distortion and residual stress generated by laser beam welding (LBW) and laser-arc hybrid welding (HYBW) on the high strength steel (HT780). Then, the experiments were simulated by 3D thermal elasticplastic analysis with FEM (Finite Element Method) which was performed with using the idealized mechanical properties considering the transformation superplasticity. From the results, the effects of the phase transformation on welding distortion and residual stress generated by LBW and HYBW were elucidated. Furthermore, the generality of the idealization of the mechanical properties was verified.

SOLID-STATE PHASE TRANSFORMATION OF WELDED METAL IN CONTROL OF WELDING DISTORTION PROCESS

Based on the tests of a build-up welding at plate edge (BWPE) and amulti-layer build-up welding on plate (MBWP), the article studies on the solid-state phasetransformations which affect welding distortion process and on the influence rule of transformationstarting temperature (TST) of welded metal to the welding residual distortion. The weldingdistortion can be decreased or controlled by the transformation volume expansion caused bysolid-state phase transformation of welded metal during the cooling. The test results of BWPE showthat when TST is at about 190 deg C, the bending distortion of welded specimen is the smallest, andits displacements at free end are decreased to 58 percent and 67 percent compared with those ofconventional welding electrodes A102 and E5015, which TST are less than room temperature and equalto 758 deg C respectively. The test results of MBWP show that when TST were at 100 approx 250 deg C.the welded specimen would appear reversible bending distortion compared with those of A102 andE5015. The maximum deflection value of reversible bending distortion in 8 mm thick plate is -2.94 mmat about 170 deg C of TST. The test results provide a valuable method to decrease or to controlwelding residual distortion.

Relation between martensitic transformation temperature range and lattice distortion ratio of NiMnGaCoCu Heusler alloys

In order to study the relation between martensitic transformation temperature range AT （where AT is the difference between martensitic transformation start and finish temperature） and lattice distortion ratio （c/a） of martensitic transforma~ tion, a series of Ni46Mnz8_xGa22Co4Cux （x = 2-5） Heusler alloys is prepared by arc melting method. The vibration sample magnetometer （VSM） experiment results show that AT increases when x 〉 4 and decreases when x 〈 4 with x increasing, and the minimal AT （about 1 K） is found at x = 4. Ambient X-ray diffraction （XRD） results show that AT is proportional to c/a for non-modulated Ni46Mn28_xGa22Co4Cux （x = 2-5） martensites. The relation between AT and c/a is in agreement with the analysis result obtained from crystal lattice mismatch model. About 1000-ppm strain is found for the sample at x = 4 when heating temperature increases from 323 K to 324 K. These properties, which allow a modulation of AT and temperature-induced strain during martensitic transformation, suggest Ni46Mn24Ga22Co4Cu4 can be a promising actuator and sensor.

Uzbekistan's coordinate system transformation from CS42 to WGS84 using distortion grid model

Currently,a non-geocentric geodetic coordinate system introduced in 1942(CS42),based on the Krasovsky ellipsoid and the Baltic system of normal heights introduced in 1977,is used for geodetic works in the Republic of Uzbekistan.The development of the GNSS network proposes a task of transition to a new geocentric system based on the World Geodetic System 1984(WGS84)ellipsoid.Many software products adopt 3-or 7-parameter conversions,which can cause errors up to several meters and are not suitable for many applications.In this case,local transformations using a grid of differences between observation points with known coordinates in both datums would give the best accuracy.In this paper,we discuss various interpolation methods(Kriging,Minimum Curvature,Inverse Distance to a Power and Radial Basis Function)to solve the distortion modeling between CS42 and WGS84 systems for national datum improvement.The results show that the distortion models share a common tendency for all interpolation methods:the maximum horizontal displacements are concentrated along the West Tien Shan lineament,which is the boundary of the relief lowering.The discrepancies between the grid-based(calculated)and GPS-measured coordinates are evaluated.Statistical and spatial analysis has confirmed that for the co-ordinate transformation from CS42 to WGS84 and vice versa,grid-based transformation with Radial Basis Function interpolation has a high accuracy transformation.Analysis of the available data across the eastern part of the country shows that some positional distortions existed between the CS42 and WGS84 datums.For the best RBF method,the magnitude of these distortions is about 0.019-0.755 m with a standard deviation of 0.015 m.

A novel image encryption scheme based on Keplers third law and random Hadamard transform

In this paper, a novel image encryption scheme based on Keplers third law and random Hadamard transform is proposed to ensure the security of a digital image. First, a set of Kepler periodic sequences is generated to permutate image data, which is characteristic of the plain-image and the Keplers third law. Then, a random Hadamard matrix is constructed by combining the standard Hadamard matrix with the hyper-Chen chaotic system, which is used to further scramble the image coefficients when the image is transformed through random Hadamard transform. In the end, the permuted image presents interweaving diffusion based on two special matrices, which are constructed by Kepler periodic sequence and chaos system. The experimental results and performance analysis show that the proposed encrypted scheme is highly sensitive to the plain-image and external keys, and has a high security and speed, which are very suitable for secure real-time communication of image data.

Walsh Hadamard Transform Based Transceiver Design for SC-FDMA with Discrete Wavelet Transform

This article proposes a new transceiver design for Single carrier frequency division multiple access(SCFDMA)system based on discrete wavelet transform(DWT). SCFDMA offers almost same structure as Orthogonal frequency division multiple access(OFDMA)with extra advantage of low Peak to Average Power Ratio(PAPR). Moreover,this article also suggests the application of Walsh Hadamard transform(WHT)for linear precoding(LP)to improve the PAPR performance of the system. Supremacy of the proposed transceiver over conventional Fast Fourier transform(FFT)based SCFDMA is shown through simulated results in terms of PAPR,spectral efficiency(SE)and bit error rate(BER).

Blind reconstruction of convolutional code based on segmented Walsh-Hadamard transform

Walsh-Hadamard transform （WriT） can solve linear error equations on Field F2, and the method can be used to recover the parameters of convolutional code. However, solving the equations with many unknowns needs enormous computer memory which limits the application of WriT. In order to solve this problem, a method based on segmented WriT is proposed in this paper. The coefficient vector of high dimension is reshaped and two vectors of lower dimension are obtained. Then the WriT is operated and the requirement for computer memory is much reduced. The code rate and the constraint length of convolutional code are detected from the Walsh spectrum. And the check vector is recovered from the peak position. The validity of the method is verified by the simulation result, and the performance is proved to be optimal.

Implementing Classical Hadamard Transform Algorithm by Continuous Variable Cluster State

Measurement-based one-way quantum computation, which uses cluster states as resources, provides an efficient model to perforrn computation. However, few of the continuous variable （CV） quantum algorithms and classical algorithms based on one-way quantum computation were proposed. In this work, we propose a method to implement the classical Hadamard transform algorithm utilizing the CV cluster state. Compared with classical computation, only half operations are required when it is operated in the one-way CV quantum computer. As an example, we present a concrete scheme of four-mode classical Hadamard transform algorithm with a four-partite CV cluster state. This method connects the quantum computer and the classical algorithms, which shows the feasibility of running classical algorithms in a quantum computer efficiently.

A generalized Hadamard transformation from new entangled state

A new entangled state ｜η 0） is proposed by the technique of integral within an ordered product. A generalized Hadamaxd transformation is derived by virtue of η; θ）, which plays a role of Hadamard transformation for （a1 sinθ - a2 cosθ） and （a1 cosθ ＋ a2 sin θ）.

Studies on Hadamard Transform Fluorimetry

Hadamard transform spectroscopy has been investigated since the later 1960’s and early 1970’s. It was demonstrated that the application of Hadamard transform technique to spectroscopy can facilitate multichannel detection of weak signal. It can be appplied not only to component analysis, but to image analysis. Now, it has been widely used in infrared spectrometry, Raman spectrometry and photothermal deflection analysis. But its application to molecular fluorimetry has not been reported up to now.

A Watermarking Algorithm Based on Wavelet and Hadamard Transform for Color Image

Digital image watermarking is a useful solution to the problem of information security, copyright and network security. In this paper, we propose a watermarking algorithm for color image based HT and DWT. A binary image as watermark is embedded into green component or blue component of color image. The algorithm can satisfy the transparence and robustness of the watermarking system very well. The experiment based on this algorithm demonstrates that the watermarking is robust to the common signal processing techniques including JPEG compressing, adding noise, low pass filter, and mosaic.

基于图像小波域自适应干扰的GAN生成人脸反取证

针对现有生成对抗网络(GAN)生成人脸反取证方法攻击迁移性不强的问题,提出了一个基于图像小波域自适应干扰的GAN生成人脸反取证方法以提升攻击迁移性.该方法通过对GAN生成人脸图像的小波域信息(即图像经过小波分解后的频率分量)施加扰动以实现其对取证模型的抵抗,并且分别在空域和频域上基于最小可觉察误差(JND)设计自适应扰动阈值,对图像不同像素点位置设置不同的扰动强度,从而增强扰动的人眼不可感知性.此外,还设计了一种数据增强方式对反取证人脸进行数据分布多样性扩充,以进一步提升攻击迁移性.实验结果表明,与6种基线方法相比,所提方法生成的反取证人脸在保证扰动对人眼不可感知前提下具有更强的攻击迁移性.

基于NDT配准与轮式里程计的激光雷达运动畸变补偿算法

激光雷达是广泛应用于同时定位与地图构建(SLAM)的测距传感器,普遍基于旋转机制收集周围环境的几何信息。当扫描期间激光雷达发生移动时,生成的点云会产生运动畸变,降低SLAM系统的准确性。在激光雷达SLAM算法设计中,为使雷达运动的估计结果更为精确,文中提出一种基于正态分布变换(NDT)和轮式里程计的激光雷达运动畸变补偿算法。首先,使用轮式里程计以高频测量方式对雷达运动进行估计,可补偿部分运动畸变。其次,设计一种基于NDT配准算法的误差处理方法,通过对点云的精准匹配降低里程计漂移的影响,实现雷达运动精确估计,进而精准补偿运动畸变。文中采用数据集以及真实场景实验对提出算法进行测试。实验结果表明,与传统里程计辅助方法相比,提出的算法能够优化运动畸变补偿效果,降低轨迹累积误差并生成全局一致地图。

基于Walsh-Hadamard变换的单像素遥感成像

本文提出了基于Walsh-Hadamard变换的单像素成像方案,并从理论分析、模拟仿真和实验验证三方面分别验证了该方案的可行性.实验上实现了350—900 nm波段对距离500 m和5000 m自然目标的128×128像素成像,成像速度0.5帧/秒.研究并讨论了单像素相机方案与计算量子成像方案的差异与共性,在此基础上分析了基于Walsh-Hadamard变换的单像素成像方案的优势与局限性.研究表明本方案同时适用于单像素相机和计算量子成像.由于单像素成像适用于应用在如红外热成像、微波成像等波段,因此在阵列探测器灵敏度或工艺达不到要求时存在优势.本文所提出的方案使得单像素成像技术向实际应用迈进了一步.

基于2^(n)-1长m序列的FHT运算及FPGA实现

在地面4G/5G移动通信中辅同步信号(Secondary Synchronization Signal,SSS)都由长为31和127的小m序列组成,在求最大相关值运算中通常都采用快速哈达码变换(Fast Hadamard Transform,FHT)来减少计算量、降低运算资源的使用,但是对于任意长序列的FHT推导没有扩展描述。文章针对基于2^(n)-1任意长度的小m序列到FHT运算的行列变换过程给出了完整的矩阵推导,并利用长为3的小m序列进行仿真验证结论的正确性,最后以5G标准中长度为127的SSS序列完成FHT的FPGA实现。

一种改进的基于Hadamard变换的快速码字搜索算法

提出了一种矢量量化码字搜索的快速算法。该算法是在Hadamard变换域内进行的。匹配码字的判决过程首先根据Chebyshev误差测度,在码书中找出一定数量Chebyshev误差最小的码字;然后运用部分失真搜索算法(PDS),在上述码字中找出其中最匹配的码字。从理论分析和模拟实验结果表明,该算法在保证较好的性能指标和视觉效果前提下,明显减少码字搜索时间。

DFSMN-T:结合强语言模型Transformer的中文语音识别

自动语音识别系统由声学模型和语言模型两部分构成,但传统语言模型N-gram存在忽略词条语义相似性、参数过大等问题,限制了语音识别字符错误率的进一步降低。针对上述问题,提出一种新型的语音识别系统,以中文音节(拼音)作为中间字符,以深度前馈序列记忆神经网络DFSMN作为声学模型,执行语音转中文音节任务,进而将拼音转汉字理解成翻译任务,引入Transformer作为语言模型;同时提出一种减少Transformer计算复杂度的简易方法,在计算注意力权值时引入Hadamard矩阵进行滤波,对低于阈值的参数进行丢弃,使得模型解码速度更快。在Aishell-1、Thchs30等数据集上的实验表明,相较于DFSMN结合3-gram模型,基于DFSMN和改进Transformer的语音识别系统在最优模型上的字符错误率相对下降了3.2%,达到了11.8%的字符错误率;相较于BLSTM模型语音识别系统,其字符错误率相对下降了7.1%。

基于DMD的光谱分辨率自适应Hadamard变换成像光谱仪

数字微镜器件(DMD)可以灵活高效地实现各阶Hadamard编码模板,设计了一种基于DMD的光谱分辨率自适应的Hadamard变换成像光谱仪,分析了仪器的结构和工作原理及实现光谱分辨率自适应的方法。它可以根据目标景物和观测要求的不同而自适应地调整光谱成像的光谱分辨率,从而在光谱准确度和数据计算量之间做出合理的折衷,既满足了对目标分类识别的要求,又提高了数据传输和处理的速度。

基于DMD的Hadamard编码模板改进设计与光谱数据修正方法研究

介绍了一种基于DMD的Hadamard变换成像光谱仪的物理模型。以7阶S矩阵为例进行论述,通过改进编码模板的设计方案,使所有色散光谱都能被严格编码为7段。提出了一种针对复原后光谱图像的修正方法,以7阶的S矩阵编码,最终可以获得6幅质量较高的光谱图像。如以n阶的S矩阵编码,最终可以获得n-1幅质量较高的光谱图像。实验结果证明了该方案的可行性和有效性。