MULTI-EPIPOLAR LINES MATCHING-BASED RAY-SPACE INTERPOLATION FOR FREE VIEWPOINT VIDEO SYSTEM

Ray-space based arbitrary viewpoint rendering without complex object segmentation or model construction is the main technology to realize Free Viewpoint Video(FVV) system for complex scenes. Ray-space interpolation and compression are two key techniques for the solution. In this paper,correlation among multiple epipolar lines in ray-space data is analyzed,and a new method of ray-space interpolation with multi-epipolar lines matching is proposed. Comparing with the pixel-based matching interpolation method and the block-based matching interpolation method,the proposed method can achieve higher Peak Signal to Noise Ratio(PSNR) in interpolating rayspace data and rendering arbitrary viewpoint images.

A Fingerprint Minutiae Matching Method Based on Line Segment Vector

Minutiae-based fingerprint matching is the most commonly used in an automatic fingerprint identification system. In this paper, we propose a minutia matching method based on line segment vector. This method uses all the detected minutiae （the ridge ending and the ridge bifurcation） in a fingerprint image to create a set of new vectors （line segment vector）. Using these vectors, we can determine a truer reference point more efficiently. In addition, this new minutiae vector can also increase the accuracy of the minutiae matching. By experiment on the public domain collections of fingerprint images fvc2004 DID set A and DB4 set A, the result shows that our algorithm can obtain an improved verification performance.

Sonar Image Registration and Mosaic Based on Line Detection and Triangle Matching

Image registration is an important research topic in the field of computer vision,in which the registration and mosaic of side-scan sonar images is the keypoints of underwater navigation.However,the image registration method of keypoints is not suitable for sonar images which do not have obvious feature points.Therefore,a method of sonar-image registration and mosaic based on line segment extraction and triangle matching is proposed in this paper.Firstly,in order to extract features from sonar image,the LSD method is introduced to detect line feature from images,and line segments are filtered by the principle of attention;after that,triangles are formed from line segments,an image transformation matrix can be calculated through the heuristic greedy algorithm from these triangles;finally,images are merged based on the transformation information.On the basis of practical tests,it is found that,the feature extraction method used in this paper can better describe the outline of underwater terrain,and there is no obvious stitching gap between the result of sonar images stitched.Experimental results show that the proposed method is effective than the keypoints method of the registration and mosaic of sonar images.

Modelling of Impedance Matching Circuit with Digital Capacitor in Narrowband Power Line Communication

Power line communication technology is used in various applications, from high voltage network to the low voltage network, as it is the only wired communication technology that is comparable with wireless communication network. It works by injecting a modulated carrier wave into the electric cables from one transceiver to another. But still, the noise level and impedance mismatch are still the main concern of this technology, particularly in the low voltage network in residential area. Power line has additive non-white noise and extremely harsh environment for communication. At the same time, there is signal attenuation along the power line caused by the impedance mismatch in the power line network. Even though these problems can be controlled using a band-pass filter and an impedance matching circuit respectively, but the impedances in the power line are time and location variant and it is rather difficult to design a circuit that allows maximum power transfer in the system all the time. Thus in this paper, a new adaptive impedance matching circuits is proposed for narrowband power line communication. This methodology is derived based on the RLC band-pass filter circuit. This concept is designed to achieve simpler configuration and higher matching resolution.

Geometrical-Analysis-Based Algorithm for Stereo Matching of Single-Lens Binocular and Multi-Ocular Stereovision System

A geometrical analysis based algorithm is proposed to achieve the stereo matching of a single-lens prism based stereovision system. By setting the multi- face prism in frontal position of the static CCD （CM-140MCL） camera, equivalent stereo images with different orientations are captured synchronously by virtual cameras which are defined by two boundary lines： the optical axis and CCD camera field of view boundary. Subsequently, the geometrical relationship between the 2D stereo images and corresponding 3D scene is established by employing two fundamentals： ray sketching in which all the pertinent points, lines, and planes are expressed in the 3D camera coordinates and the rule of refraction. Landing on this relationship, the epipolar geometry is thus obtained by fitting a set of corresponding candidate points and thereafter, stereo matching of the prism based stereovision system is obtained. Moreover, the unique geometrical properties of the imaging system allow the proposed method free from the complicated camera calibration procedures and to be easily generalized from binocular and tri-oeular to multi-ocular stereovision systems. The performance of the algorithm is presented through the experiments on the binocular imaging system and the comparison with a conventional projection method demonstrates the efficient assessment of our novel contributions.

Doppler radar by using single multicarrier pulse based on optical fibre delay lines

The proposed Doppler measurement technique shows that the Doppler measurements can be accomplished by a single pulse with multiple frequency components through optical fibre delay lines.Range and velocity ambiguity can be removed,and the velocity resolution can be improved dramatically by using long optical fibre delay lines.Furthermore,the velocity resolution can be modified by adjusting the length of optical fibre delay lines.In addition,the proposed radar can achieve high range resolution by using a single wideband pulse.As a result,the new approach can improve radar performance significantly.

Matching characteristics of magnetic field configuration and chamfered channel wall in a magnetically shielded Hall thruster

To date, the selection of the magnetic field line used to match the chamfered inner and outer channel walls in a magnetically shielded Hall thruster has not been quantitatively studied. Hence, an experimental study was conducted on a 1.35 k W magnetically shielded Hall thruster with a xenon propellant. Different magnetic field lines were chosen, and corresponding tangentially matched channel walls were manufactured and utilized. The results demonstrate that high performance and a qualified anti-sputtering effect cannot be achieved simultaneously. When the magnetic field lines that match the chamfered wall have a strength at the channel centerline of less than 12% of the maximum field strength, the channel wall can be adequately protected from ion sputtering. When the magnetic field lines have a strength ratio of 12%–20%, the thruster performance is high. These findings provide the first significant quantitative design reference for the match between the magnetic field line and chamfered channel wall in magnetically shielded Hall thrusters.

Magnet lattice design of the SSRF electron-beam transfer lines

Under three-dimensional plane geometrical constraints ( X,Y,θ ), with two asymmetric achromatic sections, the combined three-section structural FODO-like magnet lattice design is adopted and finely optimized in the SSRF electron-beam transfer lines. The magnet lattice has high flexibility and robustness, and the Courant–Snyder parameters can be easily adjusted within a wide range to meet the requirements of transmission and injection for different operation modes of the linear accelerator, booster synchrotron, and storage ring. In this article, the main parameters of the linear optics design of the SSRF electron-beam transfer lines are described, involving the physical design criteria, the total geometrical layout, the magnet lattice, and the beam Courant–Snyder parameters matching. The studies of the variant beam dynamic simulation program calculations show that the design purpose of the efficient beam transmission and injection will be basically achieved.

AN ANALYSIS OF PROPELLER LIFTING－LINE THEORY BY MATCHED ASYMPTOTIC EXPANSIONS

Lifting-line model is developed for a propeller of large aspect ratio inblade-attached noninertial system. In the analysis of the method of matched asymptoticexpansions, a fictitious velocity potential is introduced. Control equation, boundarycondition and Bernoulli equation are derived in blade- attached system. The analysis ofthe matched asymptotic expansions shows that if the advance ratio of propeller is notvery small, lifting-line theory is still valid in blade-attached noninertial system for propeller.

Improvement of Binocular Reconstruction Algorithm for Measuring 3D Pavement Texture Using a Single Laser Line Scanning Constraint

The dense and accurate measurement of 3D texture is helpful in evaluating the pavement function.To form dense mandatory constraints and improve matching accuracy,the traditional binocular reconstruction technology was improved threefold.First,a single moving laser line was introduced to carry out global scanning constraints on the target,which would well overcome the difficulty of installing and recognizing excessive laser lines.Second,four kinds of improved algorithms,namely,disparity replacement,superposition synthesis,subregion segmentation,and subregion segmentation centroid enhancement,were established based on different constraint mechanism.Last,the improved binocular reconstruction test device was developed to realize the dual functions of 3D texture measurement and precision self-evaluation.Results show that compared with traditional algorithms,the introduction of a single laser line scanning constraint is helpful in improving the measurement’s accuracy.Among various improved algorithms,the improvement effect of the subregion segmentation centroid enhancement method is the best.It has a good effect on both overall measurement and single pointmeasurement,which can be considered to be used in pavement function evaluation.

Content Addressable Memory Using Automatic Charge Balancing with Self-Control Mechanism and Master-Slave Match Line Design

Content Addressable Memory (CAM) is a type of memory used for high-speed search applications. Due to parallel comparison feature, the CAM memory leads to large power consumption which is caused by frequent pre-charge or discharge of match line. In this paper, CAM for automatic charge balancing with self-control mechanism is proposed to control the voltage swing of ML for reducing the power consumption of CAM. Another technique to reduce the power dissipation is to use MSML, it combines the master-slave architecture with charge minimization technique. Unlike the conventional design, only one match line (ML) is used, whereas in Master-Slave Match Line (MSML) one master ML and several slave MLs are used to reduce the power dissipation in CAM caused by match lines (MLs). Theoretically, the match line (ML) reduces the power consumption up to 50% which is independent of search and match case. The simulation results using Cadence tool of MSML show the reduced power consumption in CAM and modified CAM cell.

基于深度强化学习的Π型阻抗匹配网络多参数最优求解方法

针对电力线信道阻抗变化复杂、负载阻抗不匹配造成通信质量差等问题,提出一种基于深度强化学习的Π型阻抗匹配网络多参数最优求解方法,并验证分析了深度强化学习对于寻找最优匹配参数的可行性。首先,建立Π型网络结构,推导窄带匹配和宽带匹配场景下的最优匹配目标函数。其次,采用深度强化学习,利用智能体的移动模拟实际匹配网络的元件参数变化,设置含有理论值与最优匹配值参数的公式作为奖励,构建寻优匹配模型。然后,分别仿真验证了窄带匹配和宽带匹配两种应用场景并优化模型的网络参数。最后,仿真结果证明,经过训练后的最优模型运行时间较短且准确度较高,能够较好地自动匹配电力线载波通信负载阻抗变化,改善和提高电力线载波通信质量。

城市轨道交通全自动运行线路多专业速度控制与匹配设计研究

城市轨道交通多专业间的协调性是决定能否充分实现预期能力、发挥投资效益的关键环节,列车运行速度是其中一个重要方面,是城市轨道交通技术装备、技术标准、运营管理水平的重要标志。针对不同专业速度控制存在的重叠防护问题,通过剖析通信、信号、车辆、线路、环境等对全自动运行(FAO)线路列车运行速度的限制,提出列车自动运行(ATO)模式、列车自动防护(ATP)模式、蠕动模式和洗车模式4种典型运行模式下的速度匹配控制方案,讨论了根据线路等级速度拟定正线区间结构设计速度、车辆构造速度、车辆超速防护触发速度、车辆最大动态包络线计算速度、最高ATP顶篷速度、最高ATO目标速度的方法,并给出多专业匹配设计关键速度建议值。同时借助仿真手段,结合不同站间距设置与最短时间速度曲线计算,进一步针对速度等级为80,100 km/h以及120 km/h的线路分别讨论了站间距的匹配设计,建议三者站间距分别不少于1.0,1.4 km以及2.5 km。开展多专业速度控制与匹配设计的优化,有助于最大化发挥系统和设备性能,保证线路整体运营水平。

基于直线段检测和LT描述符的矿井图像线特征匹配算法

图像匹配是同步定位与地图构建(SLAM)技术中极为重要的一环,用于根据图像之间的变换关系确定相机位姿。基于线特征的图像匹配方法具有较强的鲁棒性和抗噪能力,更加适用于井下图像匹配,基于深度学习的线描述符对线段遮挡等场景具有较高的鲁棒性,性能优于传统描述符,但卷积神经网络架构的描述符将可变长度线段抽象为固定维进行描述,不利于线段长度及视差变化较大图像的匹配。针对上述问题,提出一种基于直线段检测和线描述符的矿井图像线特征匹配算法。在频域利用单参数同态滤波降低图像的照射分量,并增强反射分量,提升亮度及对比度;在YUV空间利用对比度受限的自适应直方图均衡化(CLAHE)算法对亮度分量进行均衡,使亮度分布更加均匀;变换至RGB空间提取直线段检测(LSD)线,引入一种基于Transformer架构的LT描述符构建LSD线的特征向量,最后完成线特征匹配。实验结果表明:该算法结合了同态滤波和CLAHE算法的优点,增强后图像的亮度适中,对比度良好,灰度分布均匀,增强效果优于单参数同态滤波算法、EnlightenGAN算法;该算法提取的线特征数较原图平均提升了32.92%,在不同相似纹理占比、不同程度旋转与平移变化的井下图像匹配中鲁棒性好,平均正确匹配数为61.75对,平均精度为86.83%,优于线二进制描述符(LBD)算法、LBD_NNDR算法、LT算法,能够满足矿井图像稳健匹配的需求。

基于倾斜摄影的多回输电线路实景三维模型构建系统设计

为了使改进多回输电线路三维模型更加符合实际情况,该文将倾斜摄影技术引入多回输电线路实景三维模型构建系统中,提升数据获取的精准性。硬件方面,微处理器作为指令核心处理结构,负责读取并解析指令;设计多回输电线路数据采集模块和EP3SE110F1152C4数据存储器,并利用数据存储器对系统运行过程中的多项数据进行存储;软件方面,借助倾斜摄影技术,获取多回输电线路数据,并计算其对应的比例尺和航高,再对获取的数据进行优化,消除数据中的误差,并对其进行配准处理和特征匹配以及纹理映射和归一化处理,由此完成对多回输电线路实景三维模型的构建。经过实验验证,和以往的多回输电线路实景三维模型构建系统相比,设计的基于倾斜摄影的多回输电线路实景三维模型构建系统在实际应用中模型构建完整度为95.6%,构建效果更好。

面向环境射频能量收集的宽频整流电路

整流电路是射频能量回收系统的核心,能够将射频能量转换为直流。但由于整流电路中使用的二极管具有非线性特性,导致整流效率会随频率变化而降低。为解决这一问题,本文提出一种具有宽频带的整流电路,它通过采用与二极管串联的短路线、与二极管并联的开路线以及多级微带线结构来调整阻抗匹配,实现了在宽频带范围内的高转换效率。设计的整流电路在0 dBm的输入功率下,从1.7~2.7 GHz,均达到50%的整流转换效率,最高整流转换效率为63.3%。该宽带整流电路可以运用在无线能量收集系统中。

基于PSA的中压电力线载波通信自适应阻抗匹配

在中压电力线通信中,针对复杂电器元件的种类、数量不断变化等因素导致线路阻抗不匹配而影响通信质量的问题,提出了一种中压电力线载波通信自适应阻抗匹配方法。首先,建立了中压阻抗匹配系统模型,在该模型的基础上提出了一种π型自适应阻抗匹配电路。然后,根据该电路设计了符合阻抗共轭匹配原理的目标函数,通过PID搜索算法(PID-based search algorithm, PSA)寻找最优元件参数,实现目标函数最优。最后,在此模型基础上仿真分析了PSA算法、粒子群算法(particle swarm optimization, PSO)和遗传算法(genetic algorithm, GA)的优劣性。结果表明,PSA算法在收敛速度和寻优精度方面优于PSO和GA算法,能够有效实现阻抗匹配进而改善载波通信质量,为中压电力线通信进一步研究提供了可行性方案。

基于几何约束的倾斜影像特征匹配方法

针对倾斜影像视角变换较大、重复纹理导致匹配数量少、匹配精度不高的问题,提出一种适用于倾斜影像的特征点、线分级匹配方法.首先,用直线提取(检测)算法(LSD)获取影像直线特征,并将直线特征以一定约束进行直线组对,构建直线对区域与改进的SIFT(scale-invariant feature transform)特征描述符进行匹配,使用RANSAC算法剔除误匹配,获得初始匹配结果后再进行核线约束;然后,利用已获得直线对区域进行影像局部纠正,在纠正后的局部影像上采用SIFT匹配并反算回原始影像,利用得到的同名点全局纠正倾斜影像,并进行特征点匹配与采用基于方格的运动统计算法(GMS)剔除误匹配,仍将匹配结果反算回原始影像上;最后,将仿射尺度不变特征变化结果与点拓展匹配结果进行合并,得到最终匹配结果.试验结果表明:本文方法匹配正确率与经典的仿射不变匹算法(ASIFT)的正确率相差不大,但匹配数量却是ASIFT算法的1倍~3倍.