最新刊期

    27 4 2019

      Modern Applied Optics

    • 最新科技动态,科研人员成功提出一种基于保偏3×3光纤耦合器的激光器相位解调测量系统。该系统通过光电转换和微分交叉乘法实现相位解调,简化结构并提升解调稳定性。仿真和实验结果表明,该系统解调结果与预设值吻合度高,相位波动功率谱密度一致,满足测量系统稳定可靠要求,为激光器相位测量领域带来重要突破。
      Yan BAI,Wen-guo HAN,Lu-na ZHANG,Dan CHENG,Zhuo-ya BAI,Xiao-dong WEN
      Vol. 27, Issue 4, Pages: 739-746(2019) DOI: 10.3788/OPE.20192704.0739
      摘要:To realize accurate phase measurements of a laser, a laser phase demodulation system based on 3×3 polarization maintaining (PM) fiber coupler was proposed and demonstrated. The two output signals of the 3×3 PM fiber coupler were converted to electrical signals through photoelectric conversion, and the phase information was obtained through a phase demodulation calculation based on differential cross multiplication. Through adoption of the 3×3 PM fiber coupler and PM delayed fiber structure, the Faraday rota  
      关键词:fiber opitcs;3×3 coupler;phase demodulation;phase noise   
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    • 风云三号D星成功发射,搭载的红外高光谱大气探测仪实现高精度观测。专家开发了光谱定标技术,有效订正光谱位置偏差,保证辐射精度评估和后端遥感产品开发应用。在轨数据验证显示,光谱精度偏差和标准差均可达到高精度要求,为气象卫星技术体系建设奠定了基础。
      Cheng-li QI,Fang ZHOU,Chun-qiang WU,Xiu-qing HU,Ming-jian GU
      Vol. 27, Issue 4, Pages: 747-755(2019) DOI: 10.3788/OPE.20192704.0747
      摘要:The Fengyun 3D satellite is a second-generation polar orbit meteorological satellite that was launched by China on November 15th, 2017, with a novel High-Spectral Resolution Infrared Atmospheric Sounder (HIRAS), aiming to provide hyperspectral infrared observations. The infrared high-spectral sounder needs to perform spectral calibration for each channel owing to the direct influence of spectral frequency accuracy on radiometric calibration results. First, a rough spectral calibration result was obtained by  
      关键词:spectral calibration;High-spectral Resolution Infrared Atmospheric Sounder(HIRAS);off-axis effects;LBLRTM   
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    • 科技前沿动态,光伏面板中的盖板玻璃对光捕获和面板性能至关重要。研究团队通过光线追踪模拟,系统研究了表面抗反射涂层和微图案对盖板玻璃性能的影响。结果表明,玻璃内表面图案对光电性能影响微乎其微,而抗反射膜和前表面图案均有助于提升面板性能。其中,45°金字塔形图案的应用更是展现出显著优势。
      Xue-hao GU,Lin-feng LU,Min YIN,Shu-quan TIAN,Wei REN,Gao-fei LI,Li-you YANG,Yong-le LI,Dong-dong LI
      Vol. 27, Issue 4, Pages: 756-765(2019) DOI: 10.3788/OPE.20192704.0756
      摘要:Cover glass used in photovoltaic panels plays an important role in light harvesting and in turn panel performance. In this paper, the effects on panel performance of surface antireflection (AR) coating and of micropatterns on cover glass were systematically studied by ray tracing simulation. It was found that inner surface patterns of glass have negligible effects on the optical and electrical properties of panels. Both AR film and front surface patterns benefit panel performances. A 45° pyramidal pattern i  
      关键词:photovoltaic panels;cover glass;surface pattern;antireflection coating;equivalent photon current density   
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    • 科技新闻播报:针对环境测温需求,研究团队创新提出基于端面腐蚀的双法布里-珀罗光纤温度传感探头。通过特殊光纤熔接和氢氟酸刻蚀,实现小体积、低成本、抗干扰及高灵敏度的温度传感。测试表明,该传感器在28~81℃范围内性能良好,灵敏度达64.6 pm/℃。该研究成果为复杂环境中小范围温度测量提供了潜在应用价值。
      Wen-lin FENG,Jin PENG,Jia-hao YU,Shuang XIAN,Cui CHEN
      Vol. 27, Issue 4, Pages: 766-770(2019) DOI: 10.3788/OPE.20192704.0766
      摘要:To fulfill the requirements of small volume, low cost, anti-interference ability, high sensitivity, and real-time and accurate temperature measurement in a complex environment, a double Fabry-Pérot (F-P) fiber optical temperature sensor based on end-face corrosion was proposed. The sensor was fabricated by fusion Endlessly Photonic Crystal Fiber (EPCF) with a Multi-Mode Fiber (MMF). There are three F-P reflectors: one between the Single-Mode Fiber(SMF) and EPCF, one between EPCF and MMF, and one at the inte  
      关键词:fiber optic sensing;dual Fabry-Pérot interferometer;temperature measurement;fiber corrosion   
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    • 科技新闻快讯,最新研究表明,针对大空间域激光跟踪仪测量精度问题,专家提出了创新的转站误差模型和修正方法。通过深入分析测量误差来源和影响,建立了考虑随机和系统测量误差的模型,显著提高了转站精度。实验结果表明,转站精度提升显著,为高精度激光跟踪测量技术的发展提供了有力支持。
      Hui LI,Yang ZHANG,Ren-wei ZHANG,Zhi-long ZHOU,Zhen-yuan JIA
      Vol. 27, Issue 4, Pages: 771-783(2019) DOI: 10.3788/OPE.20192704.0771
      摘要:A station-transfer model was established in this study to improve the accuracy of laser tracker station-transfer measurement in larger-scale metrology. The accuracy of the laser tracker is related to the measurement errors, such as random and system measurement errors. First, the source and precise form of measurement error of the laser tracker system was analyzed according to the measurement principle of the laser tracker. Moreover, a spatial point measurement model containing the laser tracker measurement  
      关键词:large-scale metrology;laser tracker;random measurement error;systematic measurement error;station-transfer error;Monte Carlo simulation   
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    • 最新研究在数字全息显微术领域取得突破,专家深入分析了记录距离对再现像质量的影响。他们不仅考虑了采样定理和频谱分离条件,还创新性地研究了光学传递函数离散条件和尺寸关系。实验证明,综合考虑再现条件和记录条件时,可获得高质量的再现像,横向分辨力达到2.19μm。这一成果为数字全息显微术提供了更精确的记录距离设置方法,有望推动显微成像技术的进一步发展。
      Jian-su LI,Chang-ying DANG
      Vol. 27, Issue 4, Pages: 784-794(2019) DOI: 10.3788/OPE.20192704.0784
      摘要:A reasonable recording distance sets the premise to obtain a reconstructed image with no overlap and high-quality pre-magnification digital holography. Herein, a comprehensive analysis and design of the recording distance were proposed, which combines the conditions of recording and numerical reconstruction. In addition, not only were the sampling theorem and the spectrum separation theorem considered, but the relationship between the sizes of reconstructed and amplified images, and the sampling requirement  
      关键词:digital holography;recording distance;reconstructed image;amplified image;optical transfer function   
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    • 科技新闻播报:最新研究表明,科研人员通过激光沉积技术,成功在铝合金表面制备了AlCrFeCoNiCu高熵合金涂层,显著提高了表面力学性能。他们采用田口分析与TOPSIS方法优化了工艺参数,使最佳工艺参数得以确定。涂层展现出FCC和BCC相结构,显微硬度达到509 HV0.2,是基材的5倍。这一成果为铝合金表面强化提供了新的有效途径。
      Yan-zhou LI,Yan SHI
      Vol. 27, Issue 4, Pages: 795-806(2019) DOI: 10.3788/OPE.20192704.0795
      摘要:To improve the mechanical properties of an aluminum alloy surface, high-purity Cr, Fe, Co, Ni, and Cu powders were laser deposited on the alloy by using a coaxial powder feeder to form an AlCrFeCoNiCu High-Entropy Alloy (HEA) coating. With laser power, scanning speed, and powder feeding rate selected as the factors and the wetting angle and dilution taken as the responses, a multi-objective optimization of the process parameters of laser deposition was conducted by combining the Taguchi method and the techn  
      关键词:laser technology;laser deposition;high-entropy alloy;TOPSIS;aluminum alloy   
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      Micro/Nano Technology and Fine Mechanics

    • 科技新闻播报,最近,科研人员提出了含有冗余支链的3-RPS/3n-SPS并联机构,并对其进行了深入的运动学和动力学分析。通过构建动力学补充方程,成功求解出机构中所有运动副的约束反力和机构分支作用力。此研究成果不仅为该机构的进一步研究和应用提供了理论基础,也为其他含有冗余支链的并联机构逆动力学建模提供了新思路。
      Yu-ming ZHAO
      Vol. 27, Issue 4, Pages: 807-819(2019) DOI: 10.3788/OPE.20192704.0807
      摘要:In this study, a wave 3-RPS/3n-SPS parallel mechanism with redundant limbs was proposed. To solve the inverse dynamics of the mechanism, the kinematics of the mechanism were first analyzed. The velocity and acceleration mapping relationships between the branch chains and center of the moving platform were established. Then, the kinematics model was verified by simulation, and a force analysis of the 3-RPS/3n-SPS mechanism was performed. Dynamics supplementary equations were constructed based on the coordina  
      关键词:parallel mechanism;dynamics;simulation;redundant limbs;supplementary equations   
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    • 最新科技报道,研究人员在电加热玻璃制造领域取得重大突破。他们成功开发了一种复合工艺,利用电场驱动熔融喷射沉积3D打印和UV辅助微转印技术,实现高性能电加热玻璃的批量化制造。该工艺不仅提高了透光率和导电性,还增强了附着力。实验结果表明,制得的电加热玻璃透光率高达88%,方阻低且附着力强。这一创新工艺为低成本、高性能电加热玻璃的制造提供了全新解决方案。
      Jian-jun YANG,Hong-ke LI,Xiao-yang ZHU,Quan XU,Fei WANG,Hong-bo LAN
      Vol. 27, Issue 4, Pages: 820-831(2019) DOI: 10.3788/OPE.20192704.0820
      摘要:In order to produce transparent glass heaters with high light transmittance, conductivity, and adhesion of the heating wire, a novel method that combines the advantages of electric-field-driven melt-jet-deposition 3D printing technology and UV-assisted micro-transfer technology was developed. This method can enable the low-cost, batch-based manufacture of high-performance glass heaters. First, the material for 3D printing, media for the UV-assisted micro-transfer and material for the heating wire were selec  
      关键词:transparent glass heater;composite manufacturing;electric-field-driven-melt-jet deposition 3D printing;UV-assisted micro-transfer   
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    • 科技新闻讯,研究人员成功提出一种双向压电直线作动器,该作动器采用双向螺旋箝位原理,实现双向大推力作动。通过精心设计,作动器在受到拉力和压力负载时表现出色,最大输出力可达190 N,最高速度可达2.58 mm/s,行程为60 mm。这一成果为压电直线作动器的研究和应用提供了有力支持,有望推动相关领域的快速发展。
      Ding-ji CHENG,Jun ZHANG,Fu-gang WANG
      Vol. 27, Issue 4, Pages: 832-841(2019) DOI: 10.3788/OPE.20192704.0832
      摘要:A bidirectional piezoelectric linear actuator was proposed to solve the issue of the piezoelectric linear actuator being incapable of functioning under tension and pressure load. The actuator mainly adopted the principle of the two-way screw clamping to realize two-way large-thrust actuation. Structurally, the two piezoelectric stacks were symmetrically arranged, and the trapezoidal screw nut constituted a screw clamp. By matching the driving timing of the piezoelectric stack and screw clamp, the actuator c  
      关键词:piezoelectric linear actuator;large thrust;piezoelectric stack;screw clamp;inchworm   
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    • 新闻播报:在微机电系统领域,研究人员成功提出了一种新型电容式环形微机电振动陀螺。该陀螺具备结构对称、模态特性参数相同及抗干扰性强的特点。研究团队设计了硅基敏感结构,并建立了电学参数与角速度敏感模型。实验结果显示,该陀螺谐振频率稳定,品质因数高,为高性能硅基微机电陀螺的研制提供了可行的方案。
      Zhi-wei KOU,Hui-liang CAO,Yun-bo SHI,Ying-jie ZHANG
      Vol. 27, Issue 4, Pages: 842-848(2019) DOI: 10.3788/OPE.20192704.0842
      摘要:A novel MEMS capacitive vibrating ring gyroscope was proposed in this paper based on the advantageous of the ring gyroscope: symmetric resonator, identical mode parameters and excellent anti-interference ability. The sensitive structure of silicon-based capacitive vibrating ring gyroscope with S-shaped elastic supporting beams was designed, and the operating mode and amplitude-frequency response characteristics of the gyroscope were simulated and analyzed. The electromechanical interface and the silicon ele  
      关键词:Micro-electro-mechanical System(MEMS);vibrating ring gyroscope;sensitive structure;capacitor electrode;manufacturing process   
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    • 柔顺桥式位移放大机构在精密工程领域备受关注。最新研究针对其设计分析进行了非线性建模与优化,通过能量法、有限单元法与数值拟合,实现了输入输出关系的半解析建模,预测非线性结果更快速。同时,提出了机构尺寸与厚度的综合优化策略,旨在最大化输出位移并抑制几何非线性。ANSYS仿真显示,建模误差在5%以内,优化结果有效。该研究对其他复杂柔顺机构的非线性预测与优化具有参考价值。
      Wei-lin CHEN,Qing-hua LU,Jian QIAO,Chui-wang KONG,Lu-feng LUO
      Vol. 27, Issue 4, Pages: 849-859(2019) DOI: 10.3788/OPE.20192704.0849
      摘要:Due to the advantages of compact structure and large displacement amplification ratio, compliant bridge-type displacement amplification mechanism (DAM) has increasingly gained attention in the field of precision engineering. In previous reports, the design and analysis of bridge-type DAM have been limited to the linear range. In this work, nonlinear modeling and optimization of a typical lumped bridge-type DAM were investigated. Considering the shearing effect and geometrical nonlinearity, the output-input   
      关键词:compliant mechanism;displacement amplification mechanism;shearing effect;geometrical nonlinearity;optimization   
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    • 在计量型扫描电镜位移系统领域,专家通过仿真分析,深入研究了机械位移台的振动参数。通过静力及模态分析,获取了机械位移台的结构振动特性;进一步进行谐响应分析,揭示了外界载荷频率与位移台应力、应变、变形及加速度的关系。研究结果显示,机械位移台在特定频率下存在危险振动,需在后续改进中避免并进行位移补偿。
      Chen-hui DU,Liang GONG,Xiao-yong CAI,Bo-hua YIN,Chao JIANG
      Vol. 27, Issue 4, Pages: 860-867(2019) DOI: 10.3788/OPE.20192704.0860
      摘要:To improve the stability and measurement accuracy of the positioning system of a metrological scanning electron microscope, the mechanical displacement platform in the positioning system was simulated and analyzed, and vibration parameter values were obtained. A model of the mechanical displacement platform was established according to its working conditions, and the structural vibration parameter values of the platform were acquired by conducting static and modal analysis using the finite element method. T  
      关键词:metrological scanning electron microscope;micro-displacement platform;vibration;coupling displacement;finite element analysis   
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    • 科技新闻前沿播报,双框架磁悬浮控制力矩陀螺(DGMSCMG)框架系统研究取得重要突破。专家团队成功提出基于扰动观测器和自适应反步的复合解耦控制方法,有效应对内外框架耦合力矩和谐波减速器非线性传输力矩等干扰,实现高精度角速率伺服控制。仿真和实验结果显示,扰动估计误差降低至3%以内,角速率跟踪精度高达99.2%,为DGMSCMG框架系统提供了强大的抗干扰能力和高精度控制能力。
      Lin HOU,Bang-cheng HAN
      Vol. 27, Issue 4, Pages: 868-878(2019) DOI: 10.3788/OPE.20192704.0868
      摘要:Coupling moments and nonlinear transmission torques are the main factors that influence the precise angular speed control for a gimbal system of double-gimbal magnetically suspended control moment gyro with harmonic drives. Therefore, a composite decoupling control method based on a disturbance observer and adaptive backstepping control was presented to address this problem and to achieve high precision angular speed servo control of the gimbal system. Disturbances were estimated by the designed disturbance  
      关键词:Double-Gimbals Magnetically Suspended Control Moment Gyro (DGMSCMG);gimbal system angular speed servo control;harmonic drive;disturbance observer;adaptive backstepping   
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    • 最新研究显示,针对三维椭圆振动切削过程中的颤振问题,科研人员提出了一种改进的人工蜂群算法。通过优化切削参数,有效抑制了颤振现象,使刀尖点振动幅值显著降低,工件表面粗糙度降低达70%。这一成果为精密光学元件加工提供了有力支持,展示了科技在提升加工质量方面的巨大潜力。
      Ming-ming LU,Jian-zhong CHEN,Jia-kang ZHOU,Jie-qiong LIN,Yan GU
      Vol. 27, Issue 4, Pages: 879-888(2019) DOI: 10.3788/OPE.20192704.0879
      摘要:Aiming at the problem that the chatter of the Three-Dimensional Elliptical Vibration Cutting (3D-EVC) will reduce the quality of optical components. Therefore, the chatter phenomenon in 3D-EVC process need be suppressed. The chatter problem can be regarded as an optimization problem of cutting parameters. In other words, an intelligent optimization algorithm must be used to obtain the optimal cutting parameters to meet the requirements of the chatter suppression parameters. Therefore, a Particle-Artificial   
      关键词:three-dimensional elliptical vibration cutting;chatter;Artificial Bee Colony(ABC) algorithm;parameter optimization   
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    • 科技界传来新突破,直线电机动子位置检测精度再提升。专家团队成功构造非周期正弦条纹图像,并引入梯度法亚像素测量方法,实现高精度测量。该方案通过改变条纹周期、优选强鲁棒性图像,再计算亚像素位移,最终获得动子实际位移。实验显示,相比非周期栅栏图像,新方案鲁棒性更强,测量精度高达0.02 pixel,为电机位置检测带来革命性进展。
      Jing ZHAO,Hui WANG,Xu JIANG
      Vol. 27, Issue 4, Pages: 889-900(2019) DOI: 10.3788/OPE.20192704.0889
      摘要:To improve the accuracy and anti-interference of the position detection of a linear motor mover from a target shooting source, an aperiodic sinusoidal stripe image was constructed and a sub-pixel measurement method based on the gradient method was introduced to achieve high-precision measurement of the mover position. First, by changing the stripe cycle of the sinusoidal stripe, an aperiodic sinusoidal stripe image was generated. Second, an aperiodic sinusoidal stripe image with strong robustness was selected by using the Pnatt entropy of the image. Finally, the subpixel displacement of the adjacent target image was calculated using the gradient method based on the Barron operator, and the actual displacement of the linear motor mover was obtained by combining the calibration coefficients of the calibration system. Simulation and experimental results show that when compared to the aperiodic fence image, the aperiodic sinusoidal stripe image has strong robustness and a measurement accuracy of 0.02 pixels.  
      关键词:linear motor;position measurement;aperiodic sinusoidal stripe image;fence image;gradient method   
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    • 科技新闻播报:专家在垫圈式压电六维力传感器领域取得重要进展。通过深入研究传感器的结构特点和工作原理,建立了静态灵敏度解析数学模型。该模型经过与数值模型对比验证,综合相关系数高达0.988。实验原型的平均载荷传递系数与模型相近,显示模型的有效性。该研究为传感器的多参数主动设计和优选提供了有力支持,推动了传感器技术的发展。
      Jun LIU,Jun-ling XU,Min LI,Lan QIN,Jing-cheng LIU,Deng-zhuo ZHANG
      Vol. 27, Issue 4, Pages: 901-910(2019) DOI: 10.3788/OPE.20192704.0901
      摘要:To achieve a multi-structure parameter design and optimization based on the sensitivity index of a washer-type piezoelectric six-axis force sensor, an analytical mathematical model of the static sensitivity of the sensor must be studied. First, the structural characteristics and working principle of the sensor are analyzed, and a static sensitivity analytical mathematical model is derived based on the load transfer path inside the sensor. Then, an analytical mathematical model and a mathematical model based  
      关键词:six-axis force sensor;sensitivity;analytic mathematical model;orthogonal experiment   
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      Information Sciences

    • 海上智能监测技术取得新突破,科研人员针对海上船只目标跟踪问题,提出了改进核相关滤波器的船只目标跟踪算法。该算法通过引入船只目标跟踪临界概率、卡尔曼滤波模块和目标跟踪异常处理模块,有效提升了跟踪准确率和速率。实验表明,该算法在复杂海况下表现优异,满足了海上目标跟踪的精度、实时性和适用性要求。
      Chao DONG,Bing ZHENG,Bin LI,Wei LIU
      Vol. 27, Issue 4, Pages: 911-921(2019) DOI: 10.3788/OPE.20192704.0911
      摘要:To achieve tracking of marine vessel targets and improve maritime intelligence monitoring levels, this study proposed a target tracking algorithm with improved kernelized correlation filters (KCF). First, per the characteristics of a KCF algorithm, the concept of ship target tracking critical probability was proposed for evaluating whether target tracking was abnormal. A Kalman filter module was added to the algorithm to predict the position of the tracking target at the next moment. A target tracking excep  
      关键词:ship target tracking;kernelized correlation filters;kalman filtering;tracking anomaly;complex sea conditions   
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    • 科技新闻播报:在微机电系统陀螺仪领域,专家提出了基于经验模态分解的模糊间隔阈值消噪方法。该方法通过分解信号为多个本征模函数,并针对性地进行消噪处理,最终重构得到消噪信号。实验验证表明,该方法有效去除了陀螺仪输出的噪声分量,提高了信号质量,为信号处理和有用信息提取提供了有效手段。
      Guang-wu CHEN,Wen-yuan LI,Yue YU
      Vol. 27, Issue 4, Pages: 922-931(2019) DOI: 10.3788/OPE.20192704.0922
      摘要:To reduce noise in the output of a low-cost Micro-Electro-Mechanical System (MEMS) gyroscope, an Empirical Mode Decomposition (EMD) fuzzy interval threshold denoising method was proposed. The signal was first decomposed into multiple eigenmode functions/intrinsic mode functions (IMFs) using EMD. Then the IMFs were classified into three categories in terms of their IMF characteristics: noise dominated IMF, mixed noise and information IMF, information-dominated IMF. For the mixed noise and information IMF, th  
      关键词:Micro-electro-mechanical System(MEMS);gyro denoising;Empirical Mode Decomposition(EMD);fuzzy interval threshold;Allan variance   
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    • 最新科技动态,金属材料超声检测领域取得突破。专家通过递归分析方法,成功识别出超声检测信号中的微小缺陷回波。该方法通过建模分析超声波背散射信号,发现缺陷回波信号对系统递归特性的影响。实验证明,递归图能明显显示缺陷信号的特征,且特定特征量对缺陷信号敏感。这一研究为金属材料超声检测提供了有效手段,推动了相关领域的技术进步。
      Chen-long YANG,Wei FENG,Cheng-liang BIAN,Xiao-jun ZHOU,Jing-yun CHAI
      Vol. 27, Issue 4, Pages: 932-944(2019) DOI: 10.3788/OPE.20192704.0932
      摘要:To recognize minor defect echoes from metallic material ultrasonic testing signals, the recurrence analysis method was used to analyze ultrasonic detecting signals. By modeling the backscattering signal, we describe its components. In the ultrasonic detection signal, the defect echo signal will affect the recurrence characteristics of the system. In this study, we employ the recurrence analysis method to study the backscattering defect and defect-free signals of a low carbon steel testing specimen with a di  
      关键词:metallic material;backscattered signal;recurrence analysis;recurrence plot;recurrence quantification analysis   
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    • 最新科技动态报道,图像处理领域取得突破。研究人员为解决缺少描述目标信号显著程度物理量的问题,引入光谱学中信背比概念,计算目标信号与背景平均灰度值之比,直观展示对比度。同时,针对视频低速暗弱目标检测难题,提出增强方法,通过叠加差分运算与灰度变换迭代,显著提高目标信号信背比。实验结果显示,暗弱目标显著程度大幅提升,为视频低速暗弱目标检测提供了有力支持。
      Liu ZHANG,Hao-chen ZHANG,Fu-cheng LIU,Yi-yun MAN,Jun SUN,Guan-yu ZHANG
      Vol. 27, Issue 4, Pages: 945-952(2019) DOI: 10.3788/OPE.20192704.0945
      摘要:Previous studies have used signal-to-background ratio in spectroscopy to address the lack of physical quantities that describe target signal saliency in image processing. Similar to the signal-to-noise ratio calculation method, the ratio of the average gray value of the target signal to the average gray value of the background was obtained, therefore, the contrast between the target signal and the background was visually demonstrated. However, a video enhancement method was proposed for low-speed dim target  
      关键词:image processing;signal-to-background ratio;target enhancement;low-speed dim targets   
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    • 科技新闻快报,针对存在噪声、非均匀采样等缺陷的曲面样本,最新研究提出了一种基于有界泊松曲面逼近的样点法向加权估计算法。该算法通过优化处理曲面局部样本,建立样点邻域的曲面约束,实现了样点法向的稳健估计。实验证明,在噪声水平不高于20%时,该算法可将法向计算误差控制在π/18以内,且法向过渡光滑。这为处理复杂曲面样本的样点法向估计问题提供了有效解决方案。
      Dian-zhu SUN,Zeng-kai LIANG,Jiang-hua SHEN,Wei LIN
      Vol. 27, Issue 4, Pages: 953-962(2019) DOI: 10.3788/OPE.20192704.0953
      摘要:For each point of the surface obtained from organized point cloud, the normal can be estimated by fitting a local surface approximation to the surface local sample. However, for a surface sample with defects, it is difficult to robustly approximate the local area. Therefore, it is difficult to accurately estimate the normal of the sample points. To suppress the influence of sample defects on the normal estimation of sample points, a weighted normal estimation algorithm was presented for sample points, which  
      关键词:robust normal estimation;bounded Poisson surface;surface local sample;vertex normal estimation;gain optimization   
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    • 最新研究报道,在人脸表情识别领域取得了重要突破。研究者通过构建多模深度卷积神经网络,有效融合了空间和时间特征,显著提升了视频中的人脸表情识别性能。该方法不仅克服了传统方法中手工特征和主观情感相关性小的缺陷,还在公共数据集的测试中展现出了优秀的表现,为视频人脸表情识别技术的发展提供了新的思路和方法。
      Xian-zhang PAN,Shi-qing ZHANG,Wen-ping GUO
      Vol. 27, Issue 4, Pages: 963-970(2019) DOI: 10.3788/OPE.20192704.0963
      摘要:Recognizing facial expressions in video sequences is challenging because of the difficulty in distinguishing between hand-crafted features and subjective emotions. To solve this problem, we aim to improve the performance of facial expression recognition in videos. Our method used two deep convolutional neural networks (DCNNs) (i.e., spatial and temporal convolutional neural networks) to learn the temporal-spatial expression features in videos. The spatial convolutional neural network was used to extract the spatial features of static expression images from each video frame, where as the temporal convolutional neural network was used to extract dynamic features from optical flow information hidden in multi-frame expression images of a video. The temporal-spatial features were then fused using a deep belief network. Finally, support vector machines were employed to perform facial expression classification. Based on experimental results on public RML and BAUM-1s video-based emotional datasets, our method achieved an accuracy of 71.06% and 52.18%, respectively, which is clearly better than the results of existing studies. This study thus showed that our multimodal DCNN can improve the performance of facial expression recognition in videos.  
        
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    • 科技界传来新突破,针对增材制造、逆向工程中的三角网格模型简化问题,专家提出了特征保持的混合折叠算法。该算法精准计算新顶点曲度,高效计算折叠代价,对特征区域采用边折叠,对非特征区域则三角形折叠,实现高效简化。简化后模型细节特征保持良好,变形小且效率适中,为网格模型处理提供了新的有效手段。
      Zeng-huan CAO,Chang-biao HUANG,hong ZHENG
      Vol. 27, Issue 4, Pages: 971-983(2019) DOI: 10.3788/OPE.20192704.0971
      摘要:In additive manufacturing, reverse engineering, and other fields, many triangular mesh models were used to process big data. To facilitate storage and improve processing efficiency, simplifying the mesh model was necessary. However, conflicts existed among feature preservation, simplification rate, and simplification efficiency in mesh simplification. For improved balancing of results and efficiency of simplification, a method based on curvedness was proposed to compute new vertices more precisely. In addit  
      关键词:triangle mesh;mesh simplification;hybrid collapse;feature-preserving   
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    • 科技新闻快报,最近研究揭示了相机参数在轨标定的新方法。针对“天绘一号”卫星,专家采用基于LMCCD影像的EFP光束法平差技术,有效提高了无地面控制点条件下的定位精度。经过标定,卫星定位精度上下视差显著缩小,整体定位精度提升,高程精度也大幅提高。这一成果为卫星遥感领域的研究与应用提供了有力支持。
      Jian-rong WANG,Ren-xiang WANG,Xin HU
      Vol. 27, Issue 4, Pages: 984-989(2019) DOI: 10.3788/OPE.20192704.0984
      摘要:On-orbit calibration of camera parameters is a key step in the process of enhancing positioning accuracy without the need of ground control points. Triangulation-based bundle adjustment is an efficient method for calibrating the geometric parameters of a camera by incorporating stereo imagery. However, it is necessary that the established strip model should not cause system deformation owing to the rate of attitude variation. In this study, characteristics of the payloads present in the TH-1 satellite were   
      关键词:satellite photogrammetry;on-orbit calibration;Line-Matrix Charge-Coupled Device(LMCCD) camera;bundle adjustment   
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    • 科技新闻播报:在视频编码领域,最新研究提出了联合多特征快速编码算法,针对未来视频编码标准的二叉树加四叉树结构进行了优化。该算法通过联合多个编码特征的后验概率信息,有效节省了编码时间,同时提升了分类算法的准确度。实验表明,该算法在多种配置下均可显著减少编码复杂度,同时保持视频主观质量。这一创新为视频编码技术的发展注入了新动力。
      Xin CUI,Zong-ju PENG,Fen CHEN
      Vol. 27, Issue 4, Pages: 990-999(2019) DOI: 10.3788/OPE.20192704.0990
      摘要:Future video coding considerably improves compression efficiency over that of the previous high-efficiency video coding standard. The quadtree plus binary tree structure of future video coding is more consistent with the texture of high-definition video but at the cost of tremendous computational complexity. In this study, a joint multi-feature classification algorithm was proposed to reduce the complexity of the quadtree plus binary tree block structure in future video coding. The partition mode of the cur  
      关键词:future video coding;joint multi-feature classification algorithm;quadtree plus binary tree block structure;fast coding technique   
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