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Spurious-free dynamic range improvement in a photonic time-stretched analog-to-digital converter based on third-order predistortion

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Photonics Research 2014年第5期2卷 97-101页

作者： Boyu Xu Wulue Lv Jiamu Ye Jinhai Zhou Xiaofeng Jin xianmin zhang Hao Chi Shilie Zheng Department of Information Science and Electronic Engineering Zhejiang UniversityHangzhou 310027China

Spurious-free dynamic range(SFDR)limited by intermodulation distortions is a usually accepted measure for dynamic performance of a photonic time-stretched analog-to-digital converter(ADC).In this paper,SFDR improvement in a photonic time-stretched ADC based on third-order predistortion is *** third-order predistortion is achieved optically within an integrated dual-parallel Mach–Zehnder modulator(DPMZM).The mechanism of SFDR improvement with third-order predistortion in the DPMZM is theoretically *** with a conventional scheme without predistortion,the experimental results show that the SFDR improvement of∼26 dB in the proposed scheme is proved.

关键词： converter modulator SFDR

Multi-objective Topology Optimization of Thermo-mechanical Compliant Mechanisms

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Chinese Journal of Mechanical Engineering 2011年第6期24卷 1123-1129页

作者： LI Dongmei zhang xianmin GUAN Yisheng zhang Hong WANG Nianfeng School of Mechanical andAutomotive Engineering South China University of Technology Guangzhou 510640 China Guangdong Polytechnic Normal University Guangzhou 510665 China School of Computing Science University of Alberta Edmonton AB Canada

The material characteristics of a structure will change with temperature variation,and will induce stress within the ***,the optimal design for the topology of compliant mechanisms is mainly performed in single physical ***,when compliant mechanisms work in high temperature environments,their displacement outputs are generated not only by mechanical load,but also by the temperature variation which may become the prominent ***,the influence of temperature must be considered in the *** this paper,a novel optimization method for multi-objective topology of thermo-mechanical compliant mechanisms is ***,the thermal field is analyzed with finite-element method,where the thermal strain is taken into account in the constitutive relation,and the equivalent nodal thermal load is derived with the principle of virtual *** the thermal load is converted into physical loads in elastic field,and the control equation of the thermo-mechanical compliant mechanism is ***,the mathematical model of the multi-objective topology optimization is built by incorporating both the flexibility and ***,the coupling sensitivity function and the sensitivity analysis equations of thermal steady-state response are ***,optimality criteria algorithm is employed to obtain numerical solution of the multi-objective topology *** examples show that the compliant mechanisms have better performance and are more applicable if the temperature effect is taken into account in the design *** presented modeling and analysis methods provide a new idea and an effective approach to topology optimization of compliant mechanisms in electrothermic coupling field and multiphysics fields.

关键词： compliant mechanisms topology optimization thermo-mechanical coupling multi-objective coupling sensitivity

Characterization of refractive index distribution of polymer optical fiber

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Chinese Science Bulletin 2002年第12期47卷 982-985页

作者： DAI Xinhua AI Xicheng LIU Zhimin YANG Mingjun YANG Guangying HAN Buxing XU Jian zhang xianmin WU Xin Center for Molecular Science Institute of ChemistryChinese Academy of SciencesBeijing 100080China Institute of Electronic Communication Zhejian UniversityHangzhou 310002China

A focusing method is developed to characterize the refractive index profile of polymer optical fiber (POF). Based on the refractive index profile the theoretical bandwidth and the core index exponent a (a > 0) of POF ... 详细信息

关键词： polymer optical fiber focusing method refractive index distribution bandwidth.

SPANNING TREE METHOD OF IDENTIFYING ISOMORPHISM AND TOPOLOGICAL SYMMETRY TO PLANAR KINEMATIC CHAIN WITH MULTIPLE JOINT

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Chinese Journal of Mechanical Engineering 2001年第1期14卷 27-31页

作者： Song Li Yang Jian Department of Mechanical Engingeering,Xiangtan University zhang xianmin Cao Weiqing Shantou University Xi’an University of Technology 湘潭大学机械工程学院湖南湘潭汕头大学广东西安理工大学陕西

The spanning tree method of identifying isomorphism and topological symmetry to planar kinematic chain with multiple joint is presented. Directly using the kinematic chain’s structural graph in the mechanism motion sketch or its inversion,the connected relations of components and joints can be presented through the spanning tree constructed by Depth First traversal the graph and the distribution of back edge. Then, whether two graph isomorphism and components’topological symmertry can be identified through comparing the structural characteristic of spanning tree and the distribution characteristic of back edge. The study shows that the method is effective, directly perceptible, simple and convenient, and easily dealt with by computer.

关键词： Structural graph of kinematic chain Multiple joint Isomorphism Topological symmetry Spanning tree

Nullification of GFTs fortifies bioactive folates in foxtail millet

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Journal of Integrative Plant Biology 2024年第8期66卷 1540-1543页

作者： Jianzhou Pang Wei zhang Yanyan zhang Shihui zhang Yannan Wang Hui Zhi Chunyi zhang Qiuju Liang xianmin Diao College of Life Science Hebei Normal UniversityShijiazhuang 050024China Dry Land Farming Institute of Hebei Academy of Agricultural and Forestry Sciences Key Laboratory of Crop Drought Tolerance Research of Hebei ProvinceHengshui 053000China Institute of Crop Sciences Chinese Academy of Agricultural SciencesState Key Laboratory of Crop Gene Resources and BreedingBeijing 100081China Biotechnology Research Institute Chinese Academy of Agricultural SciencesBeijing 100081China

Folates—tetrahydrofolate(THF)and its derivatives(also known collectively as vitamin B9)—are essential micronutrients for almost all living *** as carriers of one-carbon(C1)units,folates participate in the biosynthesis of numerous biomolecules and play central roles in cellular methylation reactions(Strobbe and Van Der Straeten,2017).

关键词： collective organisms vitamin

34km传感长度的布里渊光时域反射计的设计与实现

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仪器仪表学报 2005年第11期26卷 1155-1158页

作者：宋牟平章献民浙江大学信息与电子工程学系杭州310027

布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电... 详细信息

布里渊分布式光纤传感器是目前最具应用前景的分布式光纤传感技术之一,其关键是如何检测布里渊散射光信号,布里渊光时域反射计是其中较好的检测方式。针对布里渊散射光信号特点,应用光相干技术来检测布里渊散射光信号。具体采用微波电光调制产生频率可调的参考光,和散射光进行相干检测,根据散射光频移特性,应用电信号处理技术取出布里渊散射光电信号,并采用偏振控制技术来抑制相干检测的偏振相干性,再经过数字信号累加和平均处理,最后得到分布式传感信号。采用光相干检测设计方案实现了布里渊时域反射计分布式光纤传感器,并进行了34km光纤的分布式应变传感实验。

关键词：分布式光纤传感布里渊散射光相干检测传感长度

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基于泊松比的土石混填地基应力波测试研究

四川大学学报（工程科学版） 2015年第2期47卷 36-42页

作者：张宇辉张献民中国民航大学机场学院天津300300

设计土石混填料大型振动压实仪,对砂土、粉土、低液限黏性土3种土石混合材料进行不同含水量、不同含石量下振动压实实验。采集相关土压力,计算混填料试件压实过程中的动泊松比,研究不同压实状态下混填料各向变形性能。研究土石混填料动... 详细信息

设计土石混填料大型振动压实仪,对砂土、粉土、低液限黏性土3种土石混合材料进行不同含水量、不同含石量下振动压实实验。采集相关土压力,计算混填料试件压实过程中的动泊松比,研究不同压实状态下混填料各向变形性能。研究土石混填料动泊松比变化规律,建立密实状态下混填料泊松比相关性分析模型。对工程中动泊松比参数变化引发的混填料剪切波速变化进行敏感性影响分析,结果表明,工程中测试土石混填地基剪切波速时,混填料动泊松比对剪切波速影响较小,可直接采用混填料在固定含水率、固定含石量下最密实状态泊松比对现场混填材料进行相关参数标定。在此基础上建立土石混填料面波-剪切波相关性模型,并开展现场试验对模型进行验证,取得了较好效果。

关键词：土石混填料动泊松比剪切波速振动压实

整体式空间3自由度精密定位平台的优化设计与试验

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机械工程学报 2007年第3期43卷 66-71页

作者：王华张宪民华南理工大学机械工程学院广州510640

根据柔顺薄板的弹性变形原理,设计一种整体式空间三自由度柔顺并联微动平台。分析该平台的输入耦合特性,对三种输入耦合形式对定位精度的影响进行讨论。基于有限元法,给出平台的刚度模型,对平台的结构尺寸进行优化设计,并通过ANSYS仿真... 详细信息

根据柔顺薄板的弹性变形原理,设计一种整体式空间三自由度柔顺并联微动平台。分析该平台的输入耦合特性,对三种输入耦合形式对定位精度的影响进行讨论。基于有限元法,给出平台的刚度模型,对平台的结构尺寸进行优化设计,并通过ANSYS仿真分析验证优化结果的正确性。在此基础上进一步建立平台的位置正解和位置逆解方程,对平台的定位精度进行试验研究,提出一种基于理论分析模型的试验修正方法,该方法能有效提高平台的定位精度,研究表明该平台具有亚微米级的定位精度。

关键词：定位平台输入耦合优化设计位置正解

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基于路表应变和基频的基顶当量回弹模量研究

振动．测试与诊断 2021年第6期41卷 1182-1189,1241,1242页

作者：张献民刘小兰南京航空航天大学民航学院南京210016 中国民航大学机场学院天津300300 天津城建大学土木工程学院天津300384

基于全车模型与弹性层状体系道路模型的动态响应,首先,确定了道路动态检测区域为距离轮胎-路面接触点0.4~0.8 m处;其次,分析该测试区域内面层模量、面层厚度和基顶当量回弹模量对路表应变和基频的影响规律,发现路表应变随着面层模量、... 详细信息

基于全车模型与弹性层状体系道路模型的动态响应,首先,确定了道路动态检测区域为距离轮胎-路面接触点0.4~0.8 m处;其次,分析该测试区域内面层模量、面层厚度和基顶当量回弹模量对路表应变和基频的影响规律,发现路表应变随着面层模量、面层厚度和基顶当量回弹模量的增加而减小,但基频随面层厚度的增加而降低,随面层模量和基顶当量回弹模量的增加而增长;然后,借助大量的数值模型建立了距离车轮不同位置处的路表应变拟合公式、道路基频拟合公式、基顶当量回弹模量拟合公式;最后,借助现场测试结果验证了本研究方法的适用性和可靠性,为道路工程的检测维护提供依据与参考。

关键词：路表应变基频面层模量面层厚度基顶当量回弹模量