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A Study of the Use and Translation of Archaic Functional Vocabulary in the Berne Convention
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作者 HU Hong-ling 《Journal of Literature and Art Studies》 2024年第1期85-91,共7页
The archaic functional vocabulary is highly with the legal features of formality and conservativeness and still holding a place in legal English.The Berne Convention is a good example to study the use and translation ... The archaic functional vocabulary is highly with the legal features of formality and conservativeness and still holding a place in legal English.The Berne Convention is a good example to study the use and translation of the archaic functional vocabulary.By studying what archaic functional words or phrases are used in the Berne Convention,their meanings and the different use frequencies of them between the Berne Convention and the Copy Right Law of PRC,it has been found that arhcaic adverbs are used of low frequency,while some adjectives or adjectival groups as well as some prepositions or prepositional phrases are used of high frequencies.The use frequencies of the archaic functional vocabulary is higher in the Berne Convention than those in the Copy Right law of PRC.Some suggestions can be put forward to help improve translating Chinese legal documents into English or writing English legal documents. 展开更多
关键词 archaic functional vocabulary the Berne Convention use frequency translation
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Recent progress in integrated electro-optic frequency comb generation 被引量:2
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作者 Hao Sun Mostafa K.halil +1 位作者 Zifei Wang Lawrence R.Chen 《Journal of Semiconductors》 EI CAS CSCD 2021年第4期5-16,共12页
Optical frequency combs have emerged as an important tool enabling diverse applications from test-and-measurement,including spectroscopy,metrology,precision distance measurement,sensing,as well as optical and microwav... Optical frequency combs have emerged as an important tool enabling diverse applications from test-and-measurement,including spectroscopy,metrology,precision distance measurement,sensing,as well as optical and microwave waveform synthesis,signal processing,and communications.Several techniques exist to generate optical frequency combs,such as mode-locked lasers,Kerr micro-resonators,and electro-optic modulation.Important characteristics of optical frequency combs include the number of comb lines,their spacing,spectral shape and/or flatness,and intensity noise.While mode-locked lasers and Kerr micro-resonators can be used to obtain a large number of comb lines compared to electro-optic modulation,the latter provides increased flexibility in tuning the comb spacing.For some applications in optical communications and microwave photonics,a high degree of integration may be more desirable over a very large number of comb lines.In this paper,we review recent progress on integrated electro-optic frequency comb generators,including those based on indium phosphide,lithium niobate,and silicon photonics. 展开更多
关键词 electro-optic frequency comb generation integrated photonics silicon photonics integrated lithium niobate indium phosphide
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Measurement of Frequency Shift Characteristics Based on LiNbO_3 Waveguide Electro-Optic Intensity Modulator 被引量:1
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作者 Zhou Meng Hui-Juan Zhou Yi Liao Qiong Yao 《Journal of Electronic Science and Technology of China》 2008年第4期449-452,共4页
High-speed and wide-band LiNbO3 waveguide electro-optic intensity modulator has drawn great attention in the field of optical fiber communication and sensor. This paper reports the research results on the measurement ... High-speed and wide-band LiNbO3 waveguide electro-optic intensity modulator has drawn great attention in the field of optical fiber communication and sensor. This paper reports the research results on the measurement of frequency shift characteristics of Mach-Zehnder electro-optic intensity modulator. Two measurement methods of frequency shift characteristics for high and low frequency modulations are studied in theory and experiment and demonstrate different results. The realization of a multi-wavelength optical source based on Mach-Zehnder electro-optic intensity modulator has been introduced. The technique to reach the maximum intensity for interesting shift frequency, particularly for heterodyne detection of Brillouin distributed optical fiber sensing, has been given. 展开更多
关键词 BRILLOUIN electro-optic intensity modulator frequency shift LiNbO3.
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Modulation Depth Based on Frequency-shift Characteristic of LiNbO3 Waveguide Electro-optic Intensity Modulator
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作者 周会娟 孟洲 廖毅 《Journal of Measurement Science and Instrumentation》 CAS 2010年第2期125-128,共4页
The modulation depth, defined according to practical modulation results, which changes with the microwave power and its frequency, is significant for systems utilizing the frequency-shift characteristic of the LiNbO3 ... The modulation depth, defined according to practical modulation results, which changes with the microwave power and its frequency, is significant for systems utilizing the frequency-shift characteristic of the LiNbO3 waveguide Electro-Optic Intensity Modulator (EOIM). By analyzing the impedance mismatch between the microwave source and the EOIM, the effective voltage applied to the RF port of the EOIM is deprived from the microwave power and its frequency. Associating with analyses of the phase velocity mismatch between the microwave and the optical wave, the theoretical modulation depth has been obtained, which is verified by experimental results. We provide a method to choose the appropriate modulation depth to optimize the desired sideband through proper transmission bias for the system based on the frequency-shift characteristic of the EOIM. 展开更多
关键词 waveguide electro-optic intensity modulator modulation depth frequency shift distributedBriiouin optical fiber sensing
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Natural vibration and critical velocity of translating Timoshenko beam with non-homogeneous boundaries
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作者 Yanan LI Jieyu DING +1 位作者 Hu DING Liqun CHEN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2024年第9期1523-1538,共16页
In most practical engineering applications,the translating belt wraps around two fixed wheels.The boundary conditions of the dynamic model are typically specified as simply supported or fixed boundaries.In this paper,... In most practical engineering applications,the translating belt wraps around two fixed wheels.The boundary conditions of the dynamic model are typically specified as simply supported or fixed boundaries.In this paper,non-homogeneous boundaries are introduced by the support wheels.Utilizing the translating belt as the mechanical prototype,the vibration characteristics of translating Timoshenko beam models with nonhomogeneous boundaries are investigated for the first time.The governing equations of Timoshenko beam are deduced by employing the generalized Hamilton's principle.The effects of parameters such as the radius of wheel and the length of belt on vibration characteristics including the equilibrium deformations,critical velocities,natural frequencies,and modes,are numerically calculated and analyzed.The numerical results indicate that the beam experiences deformation characterized by varying curvatures near the wheels.The radii of the wheels play a pivotal role in determining the change in trend of the relative difference between two beam models.Comparing the results unearths that the relative difference in equilibrium deformations between the two beam models is more pronounced with smaller-sized wheels.When the two wheels are of equal size,the critical velocities of both beam models reach their respective minima.In addition,the relative difference in natural frequencies between the two beam models exhibits nonlinear variation and can easily exceed 50%.Furthermore,as the axial velocities increase,the impact of non-homogeneous boundaries on modal shape of translating beam becomes more significant.Although dealing with non-homogeneous boundaries is challenging,beam models with non-homogeneous boundaries are more sensitive to parameters,and the differences between the two types of beams undergo some interesting variations under the influence of non-homogeneous boundaries. 展开更多
关键词 translating beam Timoshenko beam non-homogeneous boundary natural frequency critical velocity
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Dual Frequency Transformer for Efficient SDR-to-HDR Translation
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作者 Gang Xu Qibin Hou Ming-Ming Cheng 《Machine Intelligence Research》 EI CSCD 2024年第3期538-548,共11页
The SDR-to-HDR translation technique can convert the abundant standard-dynamic-range (SDR) media resources to high-dynamic-range (HDR) ones, which can represent high-contrast scenes, providing more realistic visual ex... The SDR-to-HDR translation technique can convert the abundant standard-dynamic-range (SDR) media resources to high-dynamic-range (HDR) ones, which can represent high-contrast scenes, providing more realistic visual experiences. While recent vision Transformers have achieved promising performance in many low-level vision tasks, there are few works attempting to leverage Transformers for SDR-to-HDR translation. In this paper, we are among the first to investigate the performance of Transformers for SDR-to-HDR translation. We find that directly using the self-attention mechanism may involve artifacts in the results due to the inappropriate way to model long-range dependencies between the low-frequency and high-frequency components. Taking this into account, we advance the self-attention mechanism and present a dual frequency attention (DFA), which leverages the self-attention mechanism to separately encode the low-frequency structural information and high-frequency detail information. Based on the proposed DFA, we further design a multi-scale feature fusion network, named dual frequency Transformer (DFT), for efficient SDR-to-HDR translation. Extensive experiments on the HDRTV1K dataset demonstrate that our DFT can achieve better quantitative and qualitative performance than the recent state-of-the-art methods. The code of our DFT is made publicly available at https://github.com/CS-GangXu/DFT. 展开更多
关键词 Standard-dynamic-range to high-dynamic-range(SDR-to-HDR)translation TRANSFORMER dual frequency attention(DFA) frequency-aware feature decomposition efficient model
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Nonlinearity-Compensation-Free Optical Frequency Domain Reflectometry Based on Electrically-Controlled Optical Frequency Sweep 被引量:1
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作者 Fan Yang Ling-Jie Zhang +2 位作者 Zhi-Yao Zhang Xiao-Jun Zhou Yong Liu 《Journal of Electronic Science and Technology》 CAS CSCD 2021年第1期89-96,共8页
A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the l... A nonlinearity-compensation-free optical frequency domain reflectometry(OFDR)scheme is proposed and experimentally demonstrated based on the electrically-controlled optical frequency sweep.In the proposed scheme,the linear frequency sweep light is generated by propagating an ultra-narrow-linewidth continuous-wave(CW)light through an electro-optic frequency shifter which consists of a dual-parallel Mach-Zehnder modulator(DPMZM)and an electronic 90°hybrid,where the electro-optic frequency shifter is driven by a linear frequency modulated signal generated by a direct digital synthesizer(DDS).Experimental results show that the spatial resolution and signal-to-noise ratio(SNR)of the proposed OFDR scheme without the nonlinear phase compensation are comparable to those of OFDR employing a commercial tunable laser source(TLS),an auxiliary interferometer,and a software-based nonlinear phase compensation method.The proposed OFDR scheme is helpful to reduce the complexity of the optical structure and eliminate the difficulty of developing the nonlinear phase compensation algorithm. 展开更多
关键词 Dual-parallel Mach-Zehnder modulator(DPMZM) electro-optic frequency shifter optical fiber sensor optical frequency domain reflectometry(OFDR)
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Electro-optic Properties of DR1 Doped SiO_2 Organic/inorganic Guest-host Films
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作者 LIU Shao-lin YANG Han JIN Ru-long YAN Zhao-xu YI Mao-bin 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2009年第5期726-732,共7页
We made a comprehensive investigation on the electro-optic(EO) properties of hybrid sol-gel silica film doped with Dispersed Red 1 dye(DR1/SiO2). An important finding is that the dipoles which don't orient along ... We made a comprehensive investigation on the electro-optic(EO) properties of hybrid sol-gel silica film doped with Dispersed Red 1 dye(DR1/SiO2). An important finding is that the dipoles which don't orient along the direction of corona poling field in the films can be instantaneously poled by alternate modulation electrical field. This instant poling effect results in the EO coefficients dependent on the frequency and intensity of alternate modulation electric field, and some experiments have proved it. We also investigated the electro-optic coefficients and thickness of films at different stir temperatures(Ts) of start solution and at different number densities of DR1. Experimentally the DR1 number density was optimized to an order of 1021/cm^3 and a large EO coefficient of γ33= 37 pm/V for DR1/SiO2 film was measured by simple reflection technique at 1 kHz frequencies of modulation electric field. These findings may benefit the practical application of DR1/SiO2 films in the field of EO modulator and EO probing. 展开更多
关键词 electro-optic DR1/SiO2 Instant poling Number density frequency
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基于语料库的网络流行语翻译--以“人设崩塌”为例 被引量:1
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作者 王安民 《兰州交通大学学报》 CAS 2023年第1期151-157,共7页
网络流行语“人设崩塌”目前尚无准确译法。初步分析表明,“人设”可在上下文中译作“image”或“persona”,“崩塌”可译作“destroy”。我们据此推测“destroy”及其常用同、近义词都可与“image”和“persona”搭配,表达“人设崩塌... 网络流行语“人设崩塌”目前尚无准确译法。初步分析表明,“人设”可在上下文中译作“image”或“persona”,“崩塌”可译作“destroy”。我们据此推测“destroy”及其常用同、近义词都可与“image”和“persona”搭配,表达“人设崩塌”之义。对英国国家语料库(BNC)与当代美国英语语料库(COCA)检索结果的分析表明,“damage/destroy/spoil/ruin/wreck+image”在两个语料库中都可表达“人设崩塌”之义,虽然其使用频率不同,有些表达似仅限英国或美国英语。以上动词与“persona”在两个语料库中少有搭配,故忽略不计。同时,虽然“tarnish”与“persona”很少搭配,但其与“image”的搭配频率在BNC与COCA中都极高,符合“人设崩塌”的语义表达要求。2017年的新词“milkshake duck”也可用于翻译“人设崩塌”,但其内涵与具体用法值得注意。 展开更多
关键词 人设崩塌 翻译 语料库 搭配 频率差异
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移动凸轮变阻尼隔振装置动态性能研究
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作者 王兰 邢海军 吕书锋 《振动与冲击》 EI CSCD 北大核心 2023年第19期110-116,171,共8页
针对线性隔振器在共振区需要大阻尼才能抑制共振峰,但在高频区大阻尼不利于隔振的问题,提出了基于移动凸轮的变阻尼隔振装置,该装置主要由水平对称布置的线性阻尼器及移动凸轮组成。将该变阻尼装置用于消极隔振系统,推导了变阻尼装置的... 针对线性隔振器在共振区需要大阻尼才能抑制共振峰,但在高频区大阻尼不利于隔振的问题,提出了基于移动凸轮的变阻尼隔振装置,该装置主要由水平对称布置的线性阻尼器及移动凸轮组成。将该变阻尼装置用于消极隔振系统,推导了变阻尼装置的等效阻尼系数,建立了隔振系统的动力学方程,采用谐波平衡法得到了方程的近似解析解;通过盛金法及数值仿真得到了其位移传递率曲线,分析了主要参数对系统隔振性能的影响。与传统的线性隔振器相比,选取合适的设计参数的变阻尼隔振系统,能更有效地抑制共振峰,同时还可以在中、高频区取得很好的隔振效果,最后以车辆为例,验证了前述结论。 展开更多
关键词 移动凸轮 变阻尼隔振 共振 频率比 位移传递率
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分段阻尼隔振系统的动力学特性分析
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作者 阮子悦 邢海军 卢学礼 《动力学与控制学报》 2023年第5期44-52,共9页
针对传统线性隔振器在降低共振峰值的同时会牺牲隔振性能的矛盾,设计了一种含分段阻尼的隔振器.首先,采用移动凸轮变阻尼装置,通过凸轮廓线的设计使系统的垂向阻尼系数的受振动位移大小控制并呈现分段线性特征,分析了该装置的阻尼特性.... 针对传统线性隔振器在降低共振峰值的同时会牺牲隔振性能的矛盾,设计了一种含分段阻尼的隔振器.首先,采用移动凸轮变阻尼装置,通过凸轮廓线的设计使系统的垂向阻尼系数的受振动位移大小控制并呈现分段线性特征,分析了该装置的阻尼特性.然后将分段阻尼装置应用于隔振器中,建立了含分段阻尼的积极隔振系统模型及其动力学方程,通过能量等效原理求出了分段阻尼系统的等效线性阻尼系数,求解了简谐力激励下系统响应的理论解,并用四阶龙格-库塔法数值仿真验证了理论解的正确性.最后研究了分段阻尼隔振系统的动态特性,分析了主要参数对幅频响应特性与力传递率特性的影响.结果表明,通过合理的参数选择,分段阻尼隔振器可兼顾无阻尼隔振器与线性阻尼隔振器的优点,既能有效降低系统的共振峰值,又能保证高频区域的优秀隔振性能,为新型非线性隔振器的设计提供了理论依据. 展开更多
关键词 移动凸轮 分段阻尼 能量等效 积极隔振 幅频响应 力传递率
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通过显微图像特征抽取获得微操作目标纵向信息 被引量:9
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作者 张建勋 薛大庆 +1 位作者 卢桂章 李彬 《机器人》 EI CSCD 北大核心 2001年第1期73-77,共5页
工作于生物显微镜下的微操作机器人系统 ,是完成对生物细胞显微操作的专用操作系统 .由于各种原因 ,常规的反馈定位控制难以实现 .系统中惟一可以利用的信息是由 CCD摄像机获得的显微平面图像 ,目标的纵向信息难以获得 .本文提出了一种... 工作于生物显微镜下的微操作机器人系统 ,是完成对生物细胞显微操作的专用操作系统 .由于各种原因 ,常规的反馈定位控制难以实现 .系统中惟一可以利用的信息是由 CCD摄像机获得的显微平面图像 ,目标的纵向信息难以获得 .本文提出了一种基于系列显微图像频率特性比较的分析方法 ,完成对微操作系统中各目标体的纵向位置信息的获取 ,为本系统的标定工作和位置控制的实现奠定了基础 . 展开更多
关键词 显微图像 特征抽取 微操作系统 机器人
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BOTDR分布式光纤传感器研究进展 被引量:5
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作者 岳慧敏 代志勇 +2 位作者 刘永智 欧中华 伍波 《激光杂志》 CAS CSCD 北大核心 2007年第4期4-5,共2页
基于布里渊光时域反射(BOTDR)的分布式光纤传感器无论是在军用系统还是大型民用工程方面都具有广泛的应用前景。在给出BOTDR分布式光纤应力传感器的基本原理的基础上,详细介绍了国内外目前几种不同的BOTDR,并对其优劣进行了分析与比较... 基于布里渊光时域反射(BOTDR)的分布式光纤传感器无论是在军用系统还是大型民用工程方面都具有广泛的应用前景。在给出BOTDR分布式光纤应力传感器的基本原理的基础上,详细介绍了国内外目前几种不同的BOTDR,并对其优劣进行了分析与比较。分析表明采用微波外差检测技术的BOTDR不仅具有较高的灵敏度,还具有更低的造价。 展开更多
关键词 BOTDR 声光移频 电光移频 微波外差检测
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弹道目标中段平动补偿与微多普勒提取 被引量:19
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作者 杨有春 童宁宁 +2 位作者 冯存前 贺泽维 贺思三 《宇航学报》 EI CAS CSCD 北大核心 2011年第10期2235-2241,共7页
弹道目标高速平动会使微多普勒产生平移、倾斜和折叠,必须进行补偿处理。针对弹道目标中段平动补偿问题,本文提出了一种基于多普勒极值点信息的平动参数提取和平动补偿方法。通过将平动近似为多项式描述,将微动等效为锥旋运动,推导了瞬... 弹道目标高速平动会使微多普勒产生平移、倾斜和折叠,必须进行补偿处理。针对弹道目标中段平动补偿问题,本文提出了一种基于多普勒极值点信息的平动参数提取和平动补偿方法。通过将平动近似为多项式描述,将微动等效为锥旋运动,推导了瞬时多普勒极值点与多项式参数和微动参数的关系。在此基础上,利用最小二乘参数辨识方法估计了平动参数,实现了平动补偿和微多普勒的高精度实时提取。仿真实验验证了本文算法的有效性。 展开更多
关键词 弹道目标 微多普勒 平动补偿 时频分析 最小二乘参数辨识
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基于PLC的立体车库自动控制系统 被引量:11
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作者 姜艳华 张连勇 《计算机系统应用》 2011年第5期21-24,共4页
设计了一种升降横移式立体车库的自动控制系统。系统利用PLC与变频器,完成了升降和横移的精确定位控制,并通过MCGS组态软件技术建立了PLC和上位机之间的通信连接,实现了现场设备的实时监视、数据管理和远程控制。系统运行稳定可靠、适... 设计了一种升降横移式立体车库的自动控制系统。系统利用PLC与变频器,完成了升降和横移的精确定位控制,并通过MCGS组态软件技术建立了PLC和上位机之间的通信连接,实现了现场设备的实时监视、数据管理和远程控制。系统运行稳定可靠、适应性强、性价比高,具有广阔的应用前景。 展开更多
关键词 PLC 变频 升降横移 立体车库 控制
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基于介电响应的油纸绝缘寿命预测方法 被引量:5
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作者 刘骥 吕佳璐 +3 位作者 张明泽 池明赫 齐朋帅 陈昕 《电机与控制学报》 EI CSCD 北大核心 2021年第2期82-89,共8页
油纸绝缘是油浸式电力变压器的重要组成部分,其绝缘寿命受热老化因素影响很大。因此,针对不同温度、不同含水率下的油浸纸板的寿命预测问题进行分析,提出一种应用平移因子和纤维素反应二阶动力学方程预测不同温度、不同含水率下的油浸... 油纸绝缘是油浸式电力变压器的重要组成部分,其绝缘寿命受热老化因素影响很大。因此,针对不同温度、不同含水率下的油浸纸板的寿命预测问题进行分析,提出一种应用平移因子和纤维素反应二阶动力学方程预测不同温度、不同含水率下的油浸纸板寿命的方法。首先,针对不同含水率的油浸纸板进行变温介电谱测试和130℃条件下的加速老化试验;其次,依据频温叠加的基本原理,将所测的介电损耗曲线进行计算平移,得到相应含水率油浸纸板的平移因子,根据平移因子计算相应油浸纸板的活化能,并得出油浸纸板含水率与活化能的关系式,重新构造平移因子表达式;最后,将130℃下测得的老化试验数据和平移因子代入纤维素反应二阶动力学方程,使得该模型可以计算不同温度、不同含水率下的油纸绝缘老化寿命。 展开更多
关键词 油纸绝缘 含水率 二阶动力学方程 频温平移 寿命预测
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白光数字图象频域分析法在CCD摄象机标定中的应用 被引量:3
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作者 杨新伟 满洪高 孙海珍 《机械强度》 CAS CSCD 北大核心 2010年第1期48-52,共5页
结合标定算法和平移实验,提出利用白光数字图象频域分析法标定CCD(charge coupled device,电荷耦合图象传感器)摄象机的实验方法。采用具有随机斑点特征的平板作为标定板。利用三维精密调节架以已知位移平移标定板,借助CCD摄象机记录下... 结合标定算法和平移实验,提出利用白光数字图象频域分析法标定CCD(charge coupled device,电荷耦合图象传感器)摄象机的实验方法。采用具有随机斑点特征的平板作为标定板。利用三维精密调节架以已知位移平移标定板,借助CCD摄象机记录下平移前后的标定板图象。标定点的空间坐标由平移位移确定,其对应的象素坐标由白光数字图象频域分析法求得。最后根据标定点的空间坐标和象素坐标,利用标定算法求出CCD摄象机的内外参数。将实验结果与预设值相比较,验证该方法的正确性。 展开更多
关键词 摄象机标定 白光数字图象频域分析法 平移 随机斑点
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油纸绝缘频域介电谱归算方法研究 被引量:4
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作者 张明泽 刘骥 +4 位作者 吕佳璐 陈庆国 孙宇飞 齐朋帅 陈昕 《电机与控制学报》 EI CSCD 北大核心 2020年第12期27-34,共8页
变压器油浸纸板是其油纸绝缘系统的重要组成部分,其频域介电响应曲线受测试温度、纸板内部含水率的严重影响,为研究不同因素对其归算准确性的影响,首先,在实验室条件下制备多组不同含水率的油浸纸板试样,并针对不同含水率试样进行变温... 变压器油浸纸板是其油纸绝缘系统的重要组成部分,其频域介电响应曲线受测试温度、纸板内部含水率的严重影响,为研究不同因素对其归算准确性的影响,首先,在实验室条件下制备多组不同含水率的油浸纸板试样,并针对不同含水率试样进行变温介电谱测试;其次,通过上述测试试验结果,提出基于特征频率点的频谱平移方法,并对不同含水试样的温度介电谱进行平移归算;最后,通过不同含水率油浸纸板频域介电谱平移归算结果发现,不同水分含量油浸纸板的弛豫时间活化能会影响温度介电谱的平移趋势,随着含水率的增加,油浸纸板弛豫时间活化能呈指数增加,因此,为更好地将频谱归算方法与含水率影响激活能量的关系相结合,根据试验结果对油浸纸板的激活能量与含水率进行了定量表征,对提出的平移归算模型进行了进一步完善,并验证了不同含水率下频谱曲线频率归算方法的有效性。 展开更多
关键词 油纸绝缘 含水率 弛豫活化能 平移归算 频域介电响应
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EMD时频分析拉曼光谱和近红外光谱 被引量:2
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作者 赵肖宇 方一鸣 +2 位作者 谭峰 佟亮 翟哲 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2016年第2期424-429,共6页
用时频方法分析拉曼光谱和近红外光谱。经验模态分解光谱成为特征模态分量,模态分量比重计算显示拉曼光谱能量均匀分布于各个分量,而近红外光谱的低阶特征模态分量只承载了较少的原光谱有效信息。真实光谱和数值实验均显示,经验模态分... 用时频方法分析拉曼光谱和近红外光谱。经验模态分解光谱成为特征模态分量,模态分量比重计算显示拉曼光谱能量均匀分布于各个分量,而近红外光谱的低阶特征模态分量只承载了较少的原光谱有效信息。真实光谱和数值实验均显示,经验模态分解视拉曼光谱为调幅信号,具有高频能量吸附特性;视近红外光谱为调频信号,在一阶特征模态分量中可以较好实现高频窄带解调。一阶特征模态分量希尔伯特变换显示,经验模态分解拉曼光谱时易出现模态混叠现象。进一步在时频域分析玉米叶片近红外光谱,经验模态分解后截掉低能量的一、二阶分量,用剩余特征模态分量重构光谱信号,均方根误差为1.001 1,相关系数为0.981 3,两个指标反映出重构精度较高;分解趋势项表明在近红外光波段,吸光度随着波长的减小呈现递增趋势;特征模态分量的希尔伯特变换显示,657cm^(-1)是碱胁迫光谱特有频率,可作为碱胁迫光谱特征频率来辨识。 展开更多
关键词 时频分析 经验模态分解 希尔伯特变换 近红外光谱 拉曼光谱
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基于三维辐射能量法的船舶波浪增阻计算分析 被引量:2
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作者 洪亮 朱仁传 +1 位作者 缪国平 董国祥 《船舶力学》 EI CSCD 北大核心 2018年第7期807-817,共11页
船体辐射运动是航行船舶波浪增阻的主要原因。文章基于频域势流理论推导出三维有航速船体辐射能量的具体表达式,其中流体运动速度势的计算采用了移动脉动源格林函数法,进一步根据获得的船体水动力系数和运动计算出航行船舶辐射运动引起... 船体辐射运动是航行船舶波浪增阻的主要原因。文章基于频域势流理论推导出三维有航速船体辐射能量的具体表达式,其中流体运动速度势的计算采用了移动脉动源格林函数法,进一步根据获得的船体水动力系数和运动计算出航行船舶辐射运动引起的波阻增加,并与基于切片理论的现有方法进行了比较。对Wigley III、S175集装箱船及某型油船三类不同船型在不同航行工况下的波阻增加进行了详细的计算分析。研究表明三维辐射能量法相较于基于切片理论的方法具有更好的准确性和适用性,为船舶波阻增加的预报提供了快速有效的手段。 展开更多
关键词 移动脉动源 三维辐射能量法 阻力增加 频域
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