A new method for sampled fiber Bragg grating fabrication by use of both femtosecond laser

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《JournalofLightwaveTechnology》期刊第2页50条数据

《JournalofLightwaveTechnology》期刊第2页50条数据《Journal of Lightwave Technology》期刊第2页50条数据https:///doc/8514081923.html,academic-journal-foreign_journal-lightwave-technology_info_11_1/1.《Dynamic Provisioning of Self-Organized Consumer Grid Services Over Integrated OBS/WSON Networks》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417921.html2.《Experimental Demonstration of Highly Resilient Wavelength-Switched Optical Networks With a Multivendor Interoperable GMPLS Control Plane》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417922.html3.《Overlapped-Subcarrier Multiplexing for WDM Passive Optical Networks: Experimental Verification and Mathematical Analysis》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417923.html4.《A Highly Efficient Computational Model for FDTD Simulations of Ultrafast Electromagnetic Interactions With Semiconductor Media With CarrierHeating/Cooling Dynamics》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417924.html5.《Demonstration of Wireless Backhauling Over Long-Reach PONs》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417925.html6.《All Single-Mode Fiber Mach–Zehnder Interferometer Based on Two Peanut-Shape Structures》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020417926.html7.《Cross-Diabolo Nanoantenna for Localizing and Enhancing Magnetic Field With Arbitrary Polarization》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418029.html8.《A 25 Gbit/s Transmitter Optical Sub-Assembly Package Employing Cost-Effective TO-CAN Materials and Processes》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418030.html9.《Reconfigurable All-Optical OTDM-to-WDM ConversionUsing a Multiwavelength Ultrashort Pulse Source Based on Raman Compression》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418031.html10.《A General Characterizing Method for Ring Resonators Based on Low Coherence Measurement》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418032.html11.《Network-Coding-Based Energy Management for Next-Generation Passive Optical Networks》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418033.html12.《Green Packet Optical Transport Networks (P-OTNs) Based on Photonic PBB-TE Switches and Minimized EEE Overhead》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418034.html13.《PMD Vector Estimation Through Time-Resolved Waveform Analysis Basedon Ultrafast xy-Field Sampling》原文链接:https:///doc/8514081923.html,/academic-technology_thesis/020418035.html14.《End-to-End Multicore Multimode Fiber Optic Link Operating up to 120 Gb/s》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418036.html15.《Modal Birefringence Analysis of Strained Buried-Core Waveguides》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418037.html16.《Investigation on the Phase Noise and EVM of Digitally Modulated Millimeter Wave Signal in WDM Optical Heterodyning System》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418038.html17.《Mode Classification and Calculation in All-Solid Photonic Bandgap Fibers》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418039.html18.《Synergetic Effects of Humidity and Temperature on PMMA Based Fiber Bragg Gratings》原文链接:https:///doc/8514081923.html,/academic-technology_thesis/020418040.html19.《Broadband Chromium-Doped Fiber Amplifiers for Next-Generation Optical Communication Systems》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418041.html20.《Resonant Fiber Optic Gyroscope Using an Air-Core Fiber》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418091.html21.《Auto Bias Control Technique Based on Asymmetric Bias Dithering for Optical QPSK Modulation》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418092.html22.《Broadband Mach–Zehnder Switch for Photonic Networks on Chip》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418093.html23.《Ferroelectric Liquid Crystal Mixture Integrated Into Optical Waveguides》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418094.html24.《Fabrication of High Glass Transition Temperature Graded-Index Plastic Optical Fiber: Part 2—Fiber Fabrication and Characterizations》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418095.html25.《Demonstration of a Remotely Dual-Pumped Long-Reach PON for Flexible Deployment》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418096.html26.《Performance Analysis for Optical OFDM Transmission in Short-Range IM/DD Systems》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418097.html27.《Simultaneous Measurement of Strain and Temperature by Using a Micro-T apered Fiber Grating》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418145.html28.《Extending the Sensing Range of Brillouin Optical Time-Domain Analysis Combining Frequency-Division Multiplexing and In-Line EDFAs》原文链journal-foreign_journal-lightwave-technology_thesis/020418146.html29.《Experimental Research of an All-Polarization-Maintaining Optical Fiber Vector Hydrophone》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418147.html30.《Photonic Crystal Fiber Interferometer for Dew Detection》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418148.html31.《Impact of Loss Variations on Double-Ended Distributed Temperature Sensors Based on Raman Anti-Stokes Signal Only》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418149.html32.《Brillouin Spectrum in LEAF and Simultaneous Temperature and Strain Measurement》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418150.html33.《Reduction in the Number of Averages Required in BOTDA Sensors Using Wavelet Denoising Techniques》原文链journal-foreign_journal-lightwave-technology_thesis/020418151.html34.《Raman-Assisted Brillouin Distributed Temperature Sensor Over 100 km Featuring 2 m Resolution and 1.2 C Uncertainty》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418152.html35.《Lab-on-a-Fiber Device for Trace Vapor TNT Explosive Detection: Comprehensive Performance Evaluation》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418153.html36.《Hybrid TDM/WDM-Based Fiber-Optic Sensor Network for Perimeter Intrusion Detection》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418154.html37.《The Use of a Fiber Comb Filter Fabricated by a CO Laser Irradiation to Improve the Resolution of a Ratiometric Wavelength Measurement System》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418155.html38.《Index Guiding Photonic Liquid Crystal Fibers forPractical Applications》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418156.html39.《Etched-Core Fiber Bragg Grating Sensors Integrated With Microfluidic Channels》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418157.html40.《Superstructure Fiber Gratings Via Single Step Femtosecond Laser Inscription》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418158.html41.《Inspection T echnique for Cleaved Optical Fiber Ends Based on Fabry–Perot Interferometer》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418159.html42.《Temperature Fiber Laser Sensor Based on a Hybrid Cavity and a Random Mirror》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418160.html43.《High-Sensitivity Coherent Optical Time DomainReflectometry Employing Frequency-Division Multiplexing》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418161.html44.《Refractive-Index Sensing With Inline Core-Cladding Intermodal Interferometer Based on Silicon Nitride Nano-Coated Photonic Crystal Fiber》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418162.html45.《Miniaturized Long-Period Fiber Grating Assisted Surface Plasmon Resonance Sensor》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418163.html46.《Polarization-Dependent In-Line Mach–Zehnder Interferometer for Discrimination of Temperature and Ambient Index Sensitivities》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418164.html47.《Long-Range Coherent OFDR With Light Source Phase Noise Compensation》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418165.html48.《Polarization Mode Coupling Involved in a Capillary Optical Fiber Sensor: Modeling and Experimental Validation》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418166.html49.《Metrological Evaluation of Optical Fiber Grating-Based Sensors: An Approach Towards the Standardization》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418167.html50.《Optical Intensity-Type Refractometer for Remote Measurements Via Fiber-Optic Cables》原文链接:https:///doc/8514081923.html,/academic-journal-foreign_journal-lightwave-technology_thesis/020418168.html。

第二章光纤光栅用于检测冲击动力学...

单位代码：１０３５９学号：全ＱＱ！鱼鲤！分类号：ＴＮ２５３夺肛工学犬警ＨｅｆｅｉＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ硕士学位论文ＭＡＳＴＥＲ，ＳＤＩＳＳＥＲＴＡＴＩｏＮ论文题目：基王迸红光翅的鲑枉泣圭塾力堂挂丝堡究学位类别：堂压亟士专业名称：测试计量撞苤及邀器作者姓名：篚航导师姓名：金直蕉教援完成时间：２Ｑ！垒生垒昱学位论文独创性声明本人郑重声明：所呈交的学位论文是本人在导＿ＩＩ币指导下进行独立研究工作所取得的成果。

据我所知，除了文中特别加以标注和致谢的内容外，论文中不包含其他人已经发表或撰写过的研究成果，也不包含为获得金壁兰些太堂或其他教育机构的学位或证书而使用过的材料。

对本文成果做出贡献豹个人和集体，本人已在论文中作了明确的说明，并表示谢意。

学位论文中表达的观点纯属作者本人观点，与合肥工业大学无关。

学位论文作者签名：薛航签名日期：≯／午年牛月巧日学位论文版权使用授权书本学位论文作者完全了解金ｇ墨工些盔堂有关保留、使用学位论文的规定，即：除保密期内的涉密学位论文外，学校有权保存并向国家有关部门或机构送交论文的复印件和电子光盘，允许论文被查阅或借阅。

本人授权金ｇ蒌互些太堂可以将本学位论文的全部或部分内容编入有关数据库，允许采用影印、缩印或扫描等复制手段保存、汇编学位论文。

（保密的学位论文在解密后适用本授权书）学位论文作者签名：替航签名日期：弘睁年午月习日论文作者毕业去向工作单位：联系电话：通讯地址：指导教师签名：签名日期：０。

ｆ￥年乒月拶日Ｅ．ｍａｉｌ：邮政编码：合肥ｊｌ：业大学硕士学位论文３．３．１钻具材料属性确定在网格划分前要先确定材料的属性。

固有频率是是结构本身固有的动态特性，与结构本身的材质、形状及约束条件相关。

在模态分析中必须给出的材料属性有弹性模量、密度和泊松比。

选用钻杆材质为合金钢，通过查阅机械设计手册可知合金钢钢的属性如表３．２所示。

表３．２钻杆材料属性表Ｔａｂ３．２Ｍａｔｅｒｉａｌｐｒｏｐｅｒｔｉｅｓｏｆ＆ｉｌｌｐｉｐｅ３．３．２单元选择和网格划分对于已经建立好的几何模型，需要对其网格划分，生成包含节点和单元的有限元模型。

FBG-FP阵列的高空间分辨率高精度分布式传感研究

摘要光纤传感技术以其独特的优势，成为目前智能结构健康监测技术中研究较为广泛的技术。

针对大型结构、复合材料内部裂纹、金属结构腐蚀等主要损伤类型，由于其具有隐蔽性强、结构失效机理复杂、结构破坏程度难以判断等特点，需进行超高空间分辨率、复用容量大、精度高的传感检测。

本文采用间距极小的超短弱反射的光纤光栅（Fiber Bragg Grating，FBG）构筑的光纤光栅法布里珀罗（Fiber Bragg Grating Fabry-Perot，FBG-FP）阵列搭建传感网络，基于光频域反射技术搭建传感光路，通过对解调原理、解调算法和实验验证等相关问题的研究，实现一种具有超高空间分辨率、超大容量、高精度的全分布式光纤传感新方法与新技术。

主要研究内容如下：（1）FBG-FP阵列的传感机理与复用容量研究。

以FBG的耦合模式方程为基础推导FBG-FP的光谱数学表达式，并分析其温度和应变的传感机理。

数值模拟多重反射效应和光谱阴影效应对FBG-FP传感阵列的复用极限的制约，证明降低反射率可抑制上述两种效应，并进一步提出采用光栅间隔不小于栅长和中心波长随机分布的传感阵列可分别抑制多径反射效应和光谱阴影效应，其中波长随机分布对传感没有坏的影响。

（2）FBG-FP阵列的分布式传感解调系统的研究。

提出基于光频域反射（Optical Frequency-domain Reflectometry，OFDR）技术的FBG-FP阵列的分布式解调系统。

一方面研究传感单元高空间分辨率的定位方法，通过对可调谐光源的非线性调谐效应进行补偿，在50m的传感距离内实现82μm内的超高空间分辨率；通过计算等效光频域调谐速率和可调谐光源的时间波长转换轴，提高系统的定位稳定度和波长解调精度。

另一方面研究传感单元的波长解调方法，推导FBG-FP光谱重构的数学表达式，提出FBG-FP阵列的分布式传感解调算法。

（3）裂纹尖端检测。

温度实验测试系统解调性能，实现8557个长度为400μm、间隔为440μm、反射率约为-42dB的FBG构成的超短弱反射的FBG-FP阵列传感，传感解调空间分辨率达到840μm，温度解调精度小于0.65℃。

色散线性度可调的大啁啾FBG色散补偿器

色散线性度可调的大啁啾FBG色散补偿器张昊;邱怡申;李晖;陈怀熹;陈书明;吴会松【摘要】Dispersion compensation is a vital factor in optical fiber communication. To the traditional problem of hard-to-control dispersion linearity in large chirped FBG, the relationship between relative chirp coefficient and dispersion linearity is studied. A design of a relay dispersion compensator is demonstrated based on large chirped FBG. The compensator can optimise dispersion linearity via adjusting the ratio of second order chirp coefficient to first order chirp coefficient, with big bandwidth and feasibility of relay dispersion compensation. A numerical simulated experiment of equipping the compensator in a 500 km long, 8 channeles WDM system proves the feasibility of this design.%针对传统大啁啾FBG色散补偿技术中色散曲线线性度难以控制的问题,分析了相对啁啾系数比值与色散线性度之间的关系,依此提出一种基于大啁啾FBG的中继色散补偿器设计方案.该补偿器通过调节一阶和二阶啁啾系数的比值,实现色散曲线线性度可调的功能,且具有补偿带宽范围大、适合WDM系统远程中继补偿的特点.将该设计作为中继补偿器配置在500 km、8通道WDM系统中进行模拟实验,论证了该补偿器的效果.【期刊名称】《桂林理工大学学报》【年(卷),期】2012(032)002【总页数】5页(P276-280)【关键词】大啁啾FBG;色散补偿器;色散线性度;相对啁啾系数【作者】张昊;邱怡申;李晖;陈怀熹;陈书明;吴会松【作者单位】福建师范大学物理与光电信息科技学院,福州350007;福建江夏学院实验与实训中心,福州350007;福建师范大学物理与光电信息科技学院,福州350007;福建师范大学物理与光电信息科技学院,福州350007;福建师范大学物理与光电信息科技学院,福州350007;福建江夏学院实验与实训中心,福州350007;福建江夏学院实验与实训中心,福州350007【正文语种】中文【中图分类】TN929.11色散是光纤通信中不可避免的问题，色散补偿作为通信中的关键技术受到关注。

三大检索有关资料

一、EI分类问题EI收录的论文以期刊论文和会议论文为主，还涉及部分专著和技术报告等少量文献，本校作者被EI收录的论文主要包括期刊和会议论文，主要说明如下：1、期刊论文（Journal article）期刊论文为在正式出版刊物上发表的论文，较好辨别，有明确的刊名、年、卷、期、页码等信息，在详细收录信息中，“Document type”字段为“Journal article (JA)”，此种情况可辨别为期刊论文，详细收录信息如下：Accession number: 20121314899822（收录号）Title: Water injection test in unconsolidated strata through deep boreholebased on fiber Bragg grating monitoring（论文题目）Authors: Chai, Jing1, 2 ; Qiu, Biao1, 3; Liu, Jin-Xuan4; Li, Yi1, 2; Dong, Liang1; Zhang,Guang-Wen5; Yang, Jian-Hua5; Wang, Zhen-Ping5（作者）Author affiliation: 1 School of Energy Engineering, Xi'an University of Science andTechnology, Xi'an 710054, China （作者单位）2 Key Laboratory of Western Mine Exploitation and Hazard Prevention, Xi'anUniversity of Science and Technology, Xi'an 710054, China （作者单位）3 Mining Engineering, West Virginia University, Morgantown WV 26505,United States（作者单位）4 School of Science, Xi'an University of Science and Technology, Xi'an710054, China （作者单位）5 Yanzhou Coal Mining Company Limited, Zoucheng 272100, China （作者单位）Corresponding author: Chai, J. (chaij@)（通讯作者）Source title: Meitan Xuebao/Journal of the China Coal Society（期刊刊名）Abbreviated source title: Meitan Xuebao（期刊简略刊名）Volume: 37（卷）Issue: 2（期）Issue date: February 2012（发行日期）Publication year: 2012（出版年份）Pages: 200-205（页码）Language: Chinese（收录论文原文语种）ISSN: 02539993（连续出版物编号）CODEN: MTHPDA （期刊编码）Document type: Journal article (JA) （期刊文章）Publisher: China Coal Society, Hepingli, Beijing, 100013, China（出版单位）Abstract: In order to explore the behavior of dewatered unconsolidated strata during the process of injecting water through a borehole from the surface, a new type offiber Bragg grating(FBG) sensing system was successfully used for thereal-time strain monitoring of unconsolidated strata during a water injectionprocess into a dewatered unconsolidated strata of a coal mine. Theunconsolidated strata water injection test was implemented through aborehole from the surface at a depth of +115.83 to +135.15 m. The employedfiber Bragg grating sensing system and monitoring change of the groundwater level were introduced at the depth in the unconsolidated strata wherethe water injection was conducted through two boreholes from the surface.Water injection pressures during the test were 0.1, 0.2, 0.3 MPa, and the totalwater injection volume was 4226.84 m3. The relationship between the waterinjection pressures, water injection volume and the strain change of theunconsolidated strata, the stress and strain conditions of the unconsolidatedstrata before and after water injection were analyzed. The results show thatthe dewatering compression of the unconsolidated strata is reduced withincreasing water injection pressures and water injection volumes. Whencomparing the conditions before and after water injection, it is found that thestress of the unconsolidated strata is in tension after the injections. The FBGmonitoring system is very sensitive and stable, and it can realize the real-timestrain monitoring of the water injection process within a deep unconsolidatedstrata through a surface borehole. This FBG monitoring system and the testresult presented are very important for understanding further treatment ofsettlement in unconsolidated strata.（摘要）Number of references: 18（参考文献数）Main heading: Water injection （主题词）Controlled terms: Boreholes - Coal mines - Fiber Bragggratings - Groundwater - Monitoring - Sensors - Testing - Waterlevels （EI控制词）Uncontrolled terms: Deep boreholes - Fiber Bragg grating (fbg) - Fiber Bragg grating sensingsystem - Injection pressures - Injection process - Injectionvolume - Monitoring change - Monitoring system - Real-timestrain - Sensing systems - Strain change - Stress andstrain - Unconsolidated strata （非控制词）Classification code: 943 Mechanical and Miscellaneous Measuring Instruments - 942 Electric and Electronic Measuring Instruments - 941 Acoustical and Optical MeasuringInstruments - 801 Chemistry - 741.3 Optical Devices and Systems - 944Moisture, Pressure and Temperature, and Radiation MeasuringInstruments - 614.2 Steam Power Plant Equipment and Operation - 511.1Oil Field Production Operations - 503.1 Coal Mines - 444.2Groundwater - 423.2 Non Mechanical Properties of Building Materials: TestMethods - 612.1 Internal Combustion Engines, General（分类码）Database: Compendex（来源数据库）Compilation and indexing terms, © 2012 Elsevier Inc.（数据库版权信息）2、会议论文（Conference article）会议论文均为在国际会议上投稿的论文，会后按一定的形式进行出版，一般以连续出版物（有ISSN号）和图书/专著（有ISBN号）两种形式出版，此种形式的连续出版物和图书/专著均主要以收录出版会议论文为主，在详细收录信息中，“Document type”字段为“Conference article (CA)”，此种情况一般可辨别为会议论文，大概有四种情况，详细收录信息分别如下：（1）既有ISSN，也有ISBNAccession number: 20114514502825（收录号）Title: Analysis of key safety factors mining large section working face tosteep seams（论文题目）Authors: Shao, Xiaoping1, 2 ; Shi, Pingwu2 ; Xia, Yucheng3（作者）Author affiliation: 1 Post-doctoral Mobile Research Center of Geological Resources andGeological Engineering, Xi'An University of Science and Technology,Xi'an 710054, China（作者单位）2 Dept.of Energy Engineering, Xi'an University of Science andTechnology, Xi'an 710054, China （作者单位）3 College of Geology and Environment, Xi'an University of Science andTechnology, Xi'an 710054, China （作者单位）Corresponding author: Shao, X. (shaoxp@) （通讯作者）Source title: Advanced Materials Research（出版物名称）Abbreviated source title: Adv. Mater. Res.（出版物简略名称）Volume: 361-363（卷）Monograph title: Natural Resources and Sustainable Development（专著名称）Issue date: 2012（发行日期）Publication year: 2012（出版年份）Pages: 246-249（页码）Language: English（收录论文原文语种）ISSN: 10226680 （连续出版物编号）ISBN-13: 9783037852682 （标准书号）Document type: Conference article (CA)（文章类型）Conference name: 2011 International Conference on Energy, Environment and SustainableDevelopment, ICEESD 2011（会议名称）Conference date: October 21, 2011 - October 23, 2011（会议时间）Conference location: Shanghai, China（会议地点）Conference code: 87168 （会议编码）Publisher: Trans Tech Publications, P.O. Box 1254, Clausthal-Zellerfeld, D-38670,Germany（出版机构）Abstract: As a scientific method, the mining method of horizontal section top coalcaving [1-3] has been widely used at Urumqi coal mine in Xinjiangautonomous region. At present, the section height remains at 18∼22m inUrumqi mining area, belonging to the large section mining [4] , and hasthe possibility to further improve section height. In this paper, the mainfactors affecting safety were analyzed to the large section working face,pointing out that safety mining of the large section working face mustfinish a good job selecting a reasonable section height to maximize therecovery ratio of top coal, filling surface to block air leakage channelsupplying oxygen after mining working face, blocking and extracting gasto reduce the gas content at working face, and equipping with modernsafety testing facilities to enhance safety of the detection sensitivity atworking face in four key measures, which would ensure safety mining forlarge section faces at steep seams. © (2012) Trans Tech Publications,Switzerland.（摘要）Number of references: 6（参考文献数）Main heading: Occupational risks （主题词）Controlled terms: Coal - Coal deposits - Coal mines - Metalrecovery - Mining - Planning - Safety factor - Safetytesting - Surface testing - Sustainable development （EI控制词）Uncontrolled terms: Air leakage - Blocking and extracting gas - Detectionsensitivity - Gas content - Horizontal section - Largesection - Mining areas - Mining methods - Recoveryratio - Safety mining - Scientific method - Steep seam - Testingfacility - Top-coal caving - Working face - Xinjiang （非控制词）Classification code: 914.1 Accidents and Accident Prevention - 911.2 IndustrialEconomics - 662.1 Automobiles - 531 Metallurgy andMetallography - 524 Solid Fuels - 503.1 Coal Mines - 503 Mines andMining, Coal - 502.1 Mine and Quarry Operations - 482Mineralogy - 423.2 Non Mechanical Properties of Building Materials:Test Methods - 403 Urban and Regional Planning and Development（分类码）DOI: 10.4028//AMR.361-363.246（数字对象唯一标识符）Database: Compendex（来源数据库）Compilation and indexing terms, © 2012 Elsevier Inc（数据库版权信息）（2）既有ISSN、E-ISSN 也有ISBNAccession number: 20123615405930（收录号）Title: An eigenvector-based kernel clustering approach to detectingcommunities in complex networksAuthors: Fu, Lidong1, 2 ; Gao, Lin2Author affiliation: 1 School of Computer, Xi'an University of Science and Technology,Xi'an 710054, China2 School of Computer Science and Technology, Xidian University, Xi'an710071, ChinaCorresponding author: Fu, L. (fulidong2005@)Source title: Lecture Notes in Electrical EngineeringAbbreviated source title: Lect. Notes Electr. Eng.Volume: 156 LNEEIssue: VOL. 1Monograph title: Recent Progress in Data Engineering and Internet Technology Issue date: 2013Publication year: 2013Pages: 23-28Language: EnglishISSN: 18761100E-ISSN: 18761119 （电子连续出版物编号）ISBN-13: 9783642288067 （标准书号）Document type: Conference article (CA)Conference name: International Conference on Data Engineering and Internet Technology,DEIT 2011Conference date: March 15, 2012 - March 17, 2012Conference location: Bali, IndonesiaConference code: 92428Publisher: Springer Verlag, Tiergartenstrasse 17, Heidelberg, D-69121, GermanyAbstract: To detect communities in complex networks, we generalize themodularity density(D) to weighted variants and show how optimizing theweighted function(WD) can be formulated as a spectral clusteringproblem, as well as a weighted kernel k-means clustering problem.Wealso prove equivalence of the both clustering approaches based on WD inmathematics. Using the equivalence, we propose a neweigenvector-based kernel clustering algorithms to detecting communitiesin complex networks, called two-layer approach. Experimental resultsindicate that it have better performance comparing with either directkernel k-means algorithm or direct spectral clustering algorithm in term ofquality. © 2013 Springer-Verlag GmbH.Number of references: 10Main heading: Clustering algorithmsControlled terms: Computer aided network analysis - Eigenvalues andeigenfunctions - Functions - Internet - Population dynamics Uncontrolled terms: Clustering approach - Complex networks - Kernelclustering - Kernel k-means - Spectral clustering - Two-layerapproach - Weighted functionClassification code: 971 Social Sciences - 921.1 Algebra - 921 Mathematics - 723.5Computer Applications - 723 Computer Software, Data Handling andApplications - 721 Computer Circuits and Logic Elements - 718Telephone Systems and Related Technologies; LineCommunications - 717 Optical Communication - 716Telecommunication; Radar, Radio and TelevisionDOI: 10.1007/978-3-642-28807-4_4Database: CompendexCompilation and indexing terms, © 2012 Elsevier Inc.（3）只有ISBNAccession number: 20120614755920（收录号）Title: Experimental study on the adsorption content of coalAuthors: Cheng, L.H.1, 2; Li, S.G.1, 2; Lin, H.F.1, 2; Zhang, T.J.3Author affiliation: 1 School of Energy Engineering, Xi'an University of Science andTechnology, Xi'an, China2 Key Laboratory of Western Mine Exploitation and Hazard Prevention ofthe Ministry of Education, Xi'an, China3 College of Science, Xi'an University of Science and Technology,Xi'an, ChinaCorresponding author: Cheng, L.H.Source title: Rock Mechanics: Achievements and Ambitions - Proceedings of the 2ndISRM International Young Scholars' Symposium on Rock Mechanics Abbreviated source title: Rock Mech.: Achiev. Ambitions - Proc. ISRM Int. Young Scholars' Symp.Rock Mech.Monograph title: Rock Mechanics: Achievements and Ambitions - Proceedings of the 2ndISRM International Young Scholars' Symposium on Rock Mechanics Issue date: 2012Publication year: 2012Pages: 87-89Language: EnglishISBN-13: 9780415620802 （标准书号）Document type: Conference article (CA)Conference name: 2nd ISRM International Young Scholars' Symposium on Rock Mechanics:Achievements and AmbitionsConference date: October 14, 2011 - October 16, 2011Conference location: Beijing, ChinaConference code: 88345Sponsor: International Society for Rock Mechanics (ISRM)Publisher: Taylor and Francis Inc., 325 Chestnut St, Suite 800, Philadelphia, PA19106, United StatesAbstract: In order to study the effect of temperature and particle size on theadsorption content of coal, the tests have been completed under differenttemperature and particle size conditions for the same coal sample usingthe WY-98B adsorption constant determining device. The tests show thatin the same condition of particle size and pressure, the adsorption contentand the Langmuir adsorption constant a decrease as the temperatureincreases. In the constant temperature condition, the adsorption contentof the coal is increases as the particle size decreases or the pressureincreases, but the adsorption content tends to stable as the pressurereaches to some value. © 2012 Taylor & Francis Group.Number of references: 7Main heading: Coal researchControlled terms: Adsorption - Coal - Particle size - Rock mechanics Uncontrolled terms: Adsorption constant - Coal sample - Constant temperature - Effectof temperature - Experimental studies - Langmuiradsorption - Pressure increase - Temperature increase Classification code: 502.1 Mine and Quarry Operations - 524 Solid Fuels - 802.3 ChemicalOperations - 943.2 Mechanical Variables MeasurementsDatabase: CompendexCompilation and indexing terms, © 2012 Elsevier Inc.（4）只有ISSNAccession number: 20121915010313（收录号）Title: Research on computer simulation of mining subsidence mechanismwith FLACAuthors: Ji, Hong1; Yu, Xueyi2Author affiliation: 1Network Center, Xi'an University of Science and Technology, Xi'an,China2School of Energy Engineering, Xi'an University of Science andTechnology, Xi'an, ChinaCorresponding author: Ji, H. (modena@)Source title: Advances in Intelligent and Soft ComputingAbbreviated source title: Adv. Intell. Soft Comput.Volume: 141 AISCMonograph title: Advances in Computer Science and EngineeringIssue date: 2012Publication year: 2012Pages: 249-254Language: EnglishISSN: 18675662 （连须出版物编号）Document type: Conference article (CA)Conference name: 2012 2nd International Conference on Advances in Computer Science andEngineering, CES 2012Conference date: January 13, 2012 - January 14, 2012Conference location: Sanya, ChinaConference code: 89618Sponsor: Huazhong University of Science and Technology; InternationalCommunication Sciences Association (ICSA)Publisher: Springer Verlag, Tiergartenstrasse 17, Heidelberg, D-69121, GermanyAbstract: This paper presents an analysis method of mining subsidencemechanisms of gob. The surface above gob appears displacement anddeformation with the process of coal mining. The building foundation isaffected seriously and the building is displaced, deformed and evendestroyed. A plenty of data on the displacement and deformation iscollected in Xinmi coalfield. By means of the data, the characteristics of thedisplacement and deformation and the effects on mining buildings aresimulated with FLAC. After analysis, this paper gives the preventivemeasures of mining subsidence of gob and the protection measures ofmining buildings. © 2012 Springer-Verlag GmbH.Number of references: 5Main heading: BuildingsControlled terms: Coal deposits - Coal mines - Computer science - Computer simulation -Deformation - SubsidenceUncontrolled terms: Analysis method - Building foundations - Coal fields - Coal mining - FLAC -Mining subsidence - Preventive measures - protechtion measures -Protection measuresClassification code: 723.5 Computer Applications - 723 Computer Software, Data Handling andApplications - 722 Computer Systems and Equipment - 721 ComputerCircuits and Logic Elements - 503.1 Coal Mines - 503 Mines and Mining,Coal - 482 Mineralogy - 422 Strength of Building Materials; T est Equipmentand Methods - 421 Strength of Building Materials; Mechanical Properties -405 Construction Equipment and Methods; Surveying - 402 Buildings andTowersDOI: 10.1007/978-3-642-27948-5_34Database: CompendexCompilation and indexing terms, © 2012 Elsevier Inc.3、在版文章（Article in Press）也称正在评论中的文章，此种文章一般为期刊文章，可解释为已经被确定接受的手稿，但未正式印刷出版，是先在网上供读者预览，然后根据读者的反馈再作调整，还没有给固定的卷期号，在详细收录信息中，“Document type”字段为“Article in Press”，一般正式收录后在EI中会有正式的收录号，详细收录信息如下：Accession number: IP52229809（收录号）Article in PressTitle: Electrodeposition fabrication of Co-based superhydrophobicpowder coatings in non-aqueous electrolyteAuthors: Chen, Zhi1 ; Hao, Limei2; Duan, Mengmeng1; Chen, Changle1 Author affiliation: 1 Department of Applied Physics, Northwestern Polytechnical University,Xi'an, 710129, China2 Department of Applied Physics, Xi'an University of Science andTechnology, Xi'an, 710054, ChinaCorresponding author: Chen, Z. (c2002z@)Source title: Applied Physics A: Materials Science and ProcessingAbbreviated source title: Appl Phys AIssue date: 2012Publication year: 2012Pages: 1-5Language: EnglishISSN: 09478396 （连续出版物编号）E-ISSN: 14320630 （电子连续出版物编号）CODEN: APAMFCDocument type: Article in PressAbstract: A rapid, facile, one-step process was developed to fabricate Co-basedsuperhydrophobic powder coatings on the stainless steel surfaces with anonaqueous electrolyte by the electrodeposition method. The structureand composition of the superhydrophobic surfaces were characterized bymeans of scanning electron microscopy (SEM), X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FTIR), and contact anglemeasurement. The results show that the special hierarchical structuresalong with the low surface energy lead to the high superhydrophobicity ofthe substrate surface. The shortest process of constructing thesuperhydrophobic surface is only 30 seconds, the high contact angle isgreater than 160°, and the rolling angle is less than 2°. The method canbe used to fabricate the superhydrophobic powder coatings at anyconductive cathodic surface, and the as-prepared superhydrophobicpowder coatings have advantages of transferability, repairability, anddurability. It is expected that this facile method will accelerate thelarge-scale production of superhydrophobic material. © 2012Springer-Verlag Berlin Heidelberg.Number of references: 28Main heading: HydrophobicityControlled terms: Contact angle - Electrodeposition - Electrolytes - Fourier transforminfrared spectroscopy - Powder coatings - Scanning electronmicroscopy - Surface properties - X ray diffraction Uncontrolled terms: Electrodeposition methods - Facile method - Hierarchicalstructures - Large-scale production - Low surfaceenergy - Non-aqueous electrolytes - One-stepprocess - Repairability - Stainless steel surface - Substratesurface - Superhydrophobic - Super-hydrophobicsurfaces - SuperhydrophobicityClassification code: 702 Electric Batteries and Fuel Cells - 801 Chemistry - 803 ChemicalAgents and Basic Industrial Chemicals - 804 Chemical ProductsGenerally - 813.1 Coating Techniques - 813.2 CoatingMaterials - 931.2 Physical Properties of Gases, Liquids andSolids - 931.3 Atomic and Molecular PhysicsDOI: 10.1007/s00339-012-7263-1Database: CompendexCompilation and indexing terms, © 2012 Elsevier Inc.二、2012年全校检索情况1、SCI本校没有购买SCI数据库，图书馆工作人员会定期到西安交通大学图书馆查询我校教师被SCI收录的论文信息，并发布在图书馆主页上（具体地址：http://202.200.59.7/xxfw/scisltb.htm或http://202.200.59.7/info/5617/2510.htm，数据更新至2012年11月9日），可自行在图书馆主页检索。

可调谐超稳定窄带宽光纤激光器

可调谐超稳定窄带宽光纤激光器李子强;吕辉【摘要】介绍了一种基于商用掺铒光纤放大器、光纤布拉格光栅和可变光衰减器的可调谐、超稳定、窄带宽光纤激光器的实现方案及性能。

研究结果表明，该光纤激光器的输出功率稳定性好(1 h之内的稳定度<0.92%)，线宽窄(<52 pm)，边模抑制比高(约30 dB)，调谐范围超过20 nm。

整个系统不仅可以用作窄带宽光纤激光器，还可以作为宽带自发辐射输出光源和掺铒光纤放大器，且该系统易于实现，很容易在普通实验室里搭建。

%This paper introduces the performances of an ultrastable tunable narrow-band fiber laser and its implementation scheme.Based on the commercially available Er-doped fiber amplifier,fiber Bragg grating and variable optical attenuator,this fiber laser has high output power stability (<0.92% within one hour),narrow linewidth (<52 pm),high sidemode suppres-sion ratio (~30 dB)and large tunable range (over 20 nm).The entire system can not only be used as a narrowband fiber laser but also as a wideband amplified spontaneous emission light source and an Er-doped fiber amplifier.Furthermore,this system can be easily realized in an ordinary laboratory.【期刊名称】《光通信研究》【年(卷),期】2014(000)004【总页数】3页(P61-63)【关键词】光纤激光器;特定激光系统设计;激光光谱学【作者】李子强;吕辉【作者单位】湖北工业大学理学院，武汉 430068;湖北工业大学理学院，武汉430068【正文语种】中文【中图分类】TN2560 引言窄带宽光纤激光器在连续太赫兹波生成、微波光子、光通信、高分辨率光谱学和光传感领域都有潜在的应用前景［1－5］，因此成为研究热点。

基于FBG传感器的铁路计轴系统

基于FBG传感器的铁路计轴系统摘要：光纤布拉格光栅传感器由于其抗电磁干扰、耐腐蚀和有效使用寿命长等优点，在铁路传感领域获得了广泛应用。

基于传统光纤布拉格光栅的原理，我们设计了两种计轴解调方法，一种是基于法布里-珀罗谐振腔的滤波解调法；另一种是基于匹配布拉格光栅的解调方法。

根据提出的两种方法和列车载荷对钢轨应力分布的影响，我们设计了能够检测轨道应力的轨道传感器。

F-P腔滤波器使用波长扫描法来获得中心波长，但是这种方法的采样率较低。

匹配光纤布拉格光栅方法能有效解决温度和应力的交叉敏感问题，结构简单，体积小，因此能够满足铁路系统的计轴要求。

Axle Counter for Railway Based on Fiber Bragg Grating Sensor Abstract:For the benefit of electrical isolation,corrosion resistance and quasi-distributed detecting,Fiber Bragg Grating Sensor has been studied for high-speed railway application progressively. Up to the principle of conventional Fiber Bragg Grating Sensors,we investigate a F-P filter and a matched-FBG based demodulation scheme that can be used as the track sensor.According to the proposed strain sensing method using a F-P filter or two matched FBGs and theoretical analysis of track strain distribution under load,we design a track sensor that can detect the local axial strain.The F-P filter uses wavelength scanning to obtain center wavelength,but the sampling frequency is low. The matched-FBG approach can effectively solve the temperature and strain induced cross sensitivity problem,therefor it can meet requirements of axle-counting in rail systems.Key word:Fiber Bragg Grating；Fabry-Perot Filter；Demodulation；Axle-Counting轨道交通是采取轮轨运输方式的快速大运量公共交通的总称，具有运量大、速度快、运营安全、环保、节约能源等优点，从而使它具备了缓解城市交通拥堵，优化城市布局结构，有利于节约资源、改善环境，促进国民经济发展等社会功能。

ASTM D1238-99melt flow rates

5.1.1The apparatus shall be a dead-weight piston plastom-eter consisting of a thermostatically controlled heated steelcylinder with a die at the lower end and a weighted pistonoperating within the cylinder.The essential features of theplastometer,illustrated in Figs.1and 2,are described in5.2-5.8.All dimensional measurements shall be made when thearticle being measured is at 2365°C.5.1.2Relatively minor changes in the design and arrange-ment of the component parts have been shown to causedifferences in results among laboratories.It is important,therefore,for the best interlaboratory agreement that the designadhere closely to the description herein;otherwise,it should bedetermined that modiﬁcations do not inﬂuence the results.5.2Cylinder —The steel cylinder shall be 50.8mm indiameter,162mm in length with a smooth,straight hole9.550460.0076mm in diameter,displaced 4.8mm from thecylinder axis.Wells for a thermal sensor (thermoregulator,thermistor,etc.)and thermometer shall be provided as shownin Fig.1.A 3.2-mm plate shall be attached to the bottom of thecylinder to retain the die.A hole in this plate,centered underthe die and countersunk from below,allows free passage of theextrudate.The cylinder may be supported by at least two6.4-mm high-strength screws at the top (radially positioned atright angles to the applied load)or by at least two 10-mmdiameter rods screwed into the side of the cylinder forattaching to a vertical support.The essential dimensions of a satisfactory cylinder of this type are shown in Fig.1(Note 4).The cylinder bore should be ﬁnished by techniques known to produce approximately 12rms or better in accordance with ANSI B46.1.N OTE 4—Cylinders made of SAE 52100or other equivalent steel heat-hardened to 60–65Rockwell Hardness Scale C give good service when used at temperatures below 200°C.Cylinder liners of cobalt-chromium-tungsten alloy are also satisfactory to 300°C.5.3Die —The outside of the steel die shall be such diameter that it will fall freely to the bottom of the 9.550460.0076mm diameter hole in the cylinder (Note 5).The die shall have a smooth straight bore 2.095560.0051mm in diameter and shall be 8.00060.025mm in length.The bore and its ﬁnish are critical.It shall have no visible drill or other tool marks and no detectable eccentricity.The die bore shall be ﬁnished by techniques known to produce approximately 12rms or better in accordance with ANSI B46.1.N OTE 5—Recommended die material is tungsten carbide.Also satisfac-tory are steel,synthetic sapphire,and cobalt-chromium-tungsten alloy.5.4Piston :5.4.1The piston shall be made of steel with an insulating bushing at the top as a barrier to heat transfer from the piston to the weight.The land of the piston shall be 9.474260.0076mm in diameter and 6.3560.13mm in length.The piston design may incorporate means for land replacement,for example,having threads and ﬂats immediately above the land.Above the land,the piston shall be no larger than 8.915mminFIG.1General Arrangement of ExtrusionPlastometer FIG.2Details of ExtrusionPlastometerdiameter (Note 6).The ﬁnish of the piston foot shall be 12rmsin accordance with ANSI B46.1.If wear or corrosion is aproblem,the piston should be of stainless steel and equippedwith a detachable foot for ease of replacement.N OTE 6—To improve standardization it is preferable that the piston beguided with a loose-ﬁtting metal sleeve at the top of the cylinder.N OTE 7—Pistons of SAE 52100steel with the bottom 25mm,includingthe foot,hardened to a Rockwell hardness,C scale,of 55to 59have beenfound to give good service when used at temperatures below 200°C.5.4.2The piston shall be scribed with two reference marks4mm apart in such fashion that when the lower mark coincideswith the top of the cylinder or other suitable reference point,the bottom of the piston is 48mm above the top of the die (seeFig.1).5.4.3The combined weight of piston and load shall bewithin a tolerance of 60.5%of the selected load.5.5Heater :5.5.1The equipment must have a heater capable of heatingthe apparatus so that the temperature at 10mm above the diecan be maintained within 60.2°C of the desired temperatureduring the test.The temperature of the barrel,from 10mm to75mm above the top of the die,must be maintained within61%of the set temperature (°C).N OTE 8—At temperatures higher than 200°C this degree of temperaturecontrol may be more difficult to obtain.5.5.2Calibrate the temperature-indicating device by meansof a light-gage probe-type thermocouple or a platinum-resistance temperature sensor having a short sensing length.5The thermocouple should be encased in a metallic sheath having a diameter of approximately 1.6mm with its hot junction grounded to the end of the sheath.Insert the tempera-ture sensor into the melt from the top of the cylinder so that it is 1061mm above the upper face of the die.The temperature sensors shall be used with a potentiometer having a sensitivity of at least 0.005mV ,or a temperature readout having a sensitivity of at least 0.1°C.Calibration should also be veriﬁed at 75mm above the upper face of the die.An alternate technique for calibration is to use a sheathed thermocouple or platinum-resistance temperature sensor with tip diameter of 9.460.1mm for insertion in the bore without material present.An example of this is shown in Fig.3.Calibration of the temperature-indicating device shall be veriﬁed at each run temperature.N OTE 9—The response of the temperature sensing device may be affected by immersion level.Take care to ensure adequate insulation of the device sensor and stabilization of the barrel temperature.5.5.3Heat shall be supplied by electric band heater(s)covering the entire length of the cylinder.The heater(s)may be single-or multi-element,depending upon the manufacturer’s control means.The heater(s)plus control system must be capable of maintaining the temperature within the required 60.2°C of the set point.The temperature sensor and readout equipment must be calibrated to a traceable national standard5Round-robin data showing ﬂow rate and corresponding temperature proﬁle ofthe melt obtained using probe-type thermocouples and platinum resistance tempera-ture sensors can be obtained from ASTM Headquarters.RequestRR:D20-1094.N OTE 1—Mineral glass insulation or equivalent spacer shall be bonded to tip and SS tube.Bond material shall be low conductivity type,400°C minimum rating.Insulation jacket material shall be low conductivity type (400°C minimum rating preferred,see Note 5).N OTE 2—RTD shall be inserted into bronze tip and bonded using high conductivity,400°C rated material.Tip of RTD element shall touch the bronze tip.Minimum insertion depth of 11.2mm clearance between RTD and tip wall shall be minimized.FIG.3Example of a Temperature CalibrationDevice(that is,NIST)at least once per year.The cylinder with the heater(s)shall be lagged with38mm of foamed-glass insula-tion.An insulating plate3.2mm in thickness shall be attached to the bottom of the cylinder to minimize heat loss at this point.5.6Temperature Controller—The type of controller and sensor must be capable of meeting the required control tolerance speciﬁed in5.5.1.5.7Thermometer—Thermometers having a range of4°C graduated in0.2°C divisions may be used to indicate tempera-ture.The temperature at this point may not necessarily be the temperature of the material10mm above the die.The thermometer may be used to monitor indirectly the temperature of the material10mm above the die and may be calibrated by reference to a thermocouple or platinum resistance temperature sensor inserted in the material10mm above the die.See5.5.2 for a description of a method for measuring temperature.N OTE10—Warning:Caution should be observed with the use of a mercury-ﬁlled thermometer.Mercury vaporization occurs if the thermom-eter is broken.Mercury thermometers are not to be used at or above the boiling point of mercury,which is357°C.5.8Level—Provision shall be made for vertical alignment of the bore of the extrusion plastometer.This is necessary to minimize subtractive loads resulting from rubbing or friction between the piston tip and sidewall.Means of alignment are discussed in Appendix X1.5.9Accessory Equipment—Necessary accessories include equipment for charging samples to the cylinder,a funnel,a die plug,a tool for cutting off the extruded sample,a timer or stop watch,cleaning equipment,go/no-go gages,a balance accurate to60.001g,and,when required,a weight or weight-piston support.N OTE11—Satisfactory operation of the apparatus for polyethylenes can be ascertained by making measurements on NIST Standard Reference Materials(SRMs)certiﬁed for meltﬂow rate.The four SRMs certiﬁed under condition190/2.16are SRM1473with aﬂow rate of1.29g/min, SRM1474with aﬂow rate of5.03g/10min,SRM1496with aﬂow rate of0.26g/10min,and SRM1497with aﬂow rate of0.19g/10min.SRM 1475a is certiﬁed under condition190/3.25with aﬂow rate of2.20g/10 min.66.Test Specimen6.1The test specimen may be in any form that can be introduced into the bore of the cylinder,for example,powder, granules,strips ofﬁlm,or molded slugs.It may be desirable to preform or pelletize a powder.7.Conditioning7.1Many thermoplastic materials do not require condition-ing prior to testing.Materials which contain volatile compo-nents,are chemically reactive,or have other special character-istics most probably require appropriate conditioning procedures.Moisture not only affects reproducibility ofﬂow rate measurement but,in some types of materials,degradation is accelerated by moisture at the high temperatures used in testing.Check the applicable material speciﬁcation for any conditioning requirements before using this test.See Practice D618for appropriate conditioning practices.8.Procedural Conditions8.1Standard conditions of test are given in Table1.Test conditions shall be shown as:Condition___/___,where the temperature in degrees Celsius is shownﬁrst,followed by the weight in kilograms.For example:Condition190/2.16.8.2The following conditions have been found satisfactory for the material listed:Material ConditionAcetals(copolymer and homopolymer)190/2.16190/1.05 Acrylics230/1.2230/3.8 Acrylonitrile-butadiene-styrene200/5.0230/3.8220/10Acrylonitrile/butadiene/styrene/polycarbonate230/3.8250/1.2 blends265/3.8265/5.0 Cellulose esters190/0.325190/2.16190/21.60210/2.16 Ethylene-chlorotriﬂuoroethylene copolymer271.5/2.16Ethylene-tetraﬂuoroethylene copolymer297/5.0Nylon275/0.325235/1.0235/2.16235/5.0275/5.0Perﬂuoro(ethylene-propylene)copolymer372/2.16Perﬂuoroalkoxyalkane372/5.0Polycaprolactone125/2.1680/2.16 Polychlorotriﬂuorethylene265/12.5Polyethylene125/0.325125/2.162.50/1.2190/0.325190/2.16190/21.60190/10310/12.5Polycarbonate300/1.2Polymonochlorotriﬂuoroethylene265/21.6265/31.6Polypropylene230/2.16Polystyrene200/5.0230/1.2230/3.8190/5.0 Polyterephthalate250/2.16210/2.16285/2.16Poly(vinyl acetal)150/21.6Poly(vinylideneﬂuoride)230/21.6230/5.0Poly(phenylene sulﬁde)315/5.0Styrene acrylonitrile220/10230/10230/3.8Styrenic Thermoplastic Elastomer190/2.16200/5.0 Thermoplastic Elastomer-Ether-Ester190/2.16220/2.16230/2.16240/2.16250/2.16 Thermoplastic elastomers(TEO)230/2.16Vinylideneﬂuoride copolymers230/21.6230/5.0for T m5100°use120/5.0or21.6 N OTE12—Some materials may require special materials of construc-tion or handling for performing this test.Please refer to the material speciﬁcation for appropriate recommendations.8.3If more than one condition is used and the material is polyethylene,the determination of Flow Rate Ratio(FRR)has been found to be useful.FRR is a dimensionless number derived by dividing theﬂow rate at Condition190/10by the ﬂow rate at Condition190/2.16.N OTE13—When determining such a ratio ofﬂow rates for a material at the same temperature under different loads,it has been found that precision is maximized when one operator uses one Procedure(A or B), the same plastometer,and the same die for both measurements(the die need not be removed from the plastometer between the two determina-tions).6These standard polyethylenes are available from the National Institute of Standards and Technology,Office of Standard Reference Materials,Washington,DC20234.9.Procedure A—Manual Operation9.1Select conditions of temperature and load from Table 1in accordance with material speciﬁcations such that ﬂow rateswill fall between 0.15to 50g/10min.9.2Ensure that the bore of the extrusion plastometer isproperly aligned in the vertical direction.(See Appendix X1.)9.3Inspect the apparatus and die for cleanliness.If it is notclean,see 9.11.N OTE 14—The degree of cleanliness can signiﬁcantly inﬂuence theﬂow rate results,therefore a thorough method of cleaning must beestablished.It has been found that three swabs of the barrel is satisfactoryfor most materials and that the die,barrel,and piston are more easilycleaned while hot.9.4Check the die bore diameter with appropriately sized no-go/go gages prior to testing.Make frequent checks to determine whether the die diameter (tested with die at 2365°C)is within the tolerances given in 5.3.N OTE 15—Cleaning and usage can result in a die diameter that is out of speciﬁcations.Data has shown that erroneous results will be obtained ifthe die diameter is not within the appropriate tolerances.9.5Verify that the temperature is stable and within 60.2°Cof the appropriate test temperature as speciﬁed in 5.5.1.9.6Insert the die and the piston.The temperature of thecylinder with the piston and die in place must be stable at theappropriate test temperature 15min before testing is begun.When equipment is used repetitiously,it should not be neces-sary to heat the piston and die for 15min.9.7Remove the piston and place it on an insulated surface.Charge the cylinder within 1min with a weighed portion of the sample according to the expected ﬂow rate,as given in Table 2.Reinsert the piston and add the appropriate weight.N OTE 16—Experience has shown that for the best reproducibility the piston should operate within the same part of the cylinder for each measurement.The piston is scribed so the starting point for each extrusion is roughly the same.Some excess of material over the minimum required for the actual ﬂow measurement portion of the test is provided by the charging weights shown in Table 2.This is necessary to achieve a void-free extrudate and ﬂow equilibrium before start of rate measure-ments.N OTE 17—It is frequently helpful to take interim cuts of the extrudateat uniform time intervals during the speciﬁed extrusion time.Weights ofthese individual cuts give an indication of the presence of bubbles whichmay be masked due to their size or to opacity of the sample.Thistechnique is particularly helpful in the case of highly pigmented materials.Forcing out some of the resin manually during the preheat period ofteneliminates bubbles in the test extrudate.9.8Allow time for the material to soften and begin to melt,and then purge some material to a position such that subse-quent travel of the piston will position the lower scribe mark at the reference start position 7.060.5min from the completion of the charge.Purge must be completed at least 2min prior toTABLE 1Standard Test Conditions,Temperature,and LoadConditionTemperature,°C Total Load Including Piston,kg Approximate Pressure Standard DesignationkPa psi 80/2.1680 2.16125/0.3251250.32544.8 6.5125/2.16125 2.16298.243.25150/2.16150 2.16298.243.25190/0.3251900.32544.8 6.5190/2.16190 2.16298.243.25190/21.6019021.602982.2432.5200/5.0200 5.0689.5100.0230/1.2230 1.2165.424.0230/3.8230 3.8524.076.0265/12.526512.51723.7250.0275/0.3252750.32544.8 6.5230/2.16230 2.16298.243.25190/1.05190 1.05144.721.0190/10.019010.01379.0200.0300/1.2300 1.2165.424.0190/5.0190 5.0689.5100.0235/1.0235 1.0138.220.05235/2.16235 2.16298.243.25235/5.0235 5.0689.5100.0250/2.16250 2.16298.243.25310/12.531012.51723.7250.0210/2.16210 2.16298.243.25285/2.16285 2.16298.243.25315/5.0315 5.0689.5100.0372/2.16372 2.16298.243.25372/5.0372 5.0689.5100297/5.0297 5.0689.5100230/21.623021.62982.2432.5230/5.0230 5.0689.5100265/21.626521.62982.2432.5265/31.626531.64361.2632.5271.5/2.16271.5 2.16298.243.25220/1022010.01379.0200.0250/1.2250 1.2165.424.0265/3.8265 3.8524.076.0265/5265 5.0689.5100.0start of the test for materials having melt ﬂow rates less than 10g/10min.N OTE 18—It has been found that purging within 60s of the start timewill result in higher variability in the data.N OTE 19—There may be cases where the 7.060.5min is too much ornot enough preheat time.For those materials,provisions must be in thematerial documents.It is necessary to refer to the appropriate materialdocument before beginning any test.N OTE 20—Additional care may be necessary to prevent thermal degra-dation in the extrusion plastometer.This is sometimes done by the additionof an appropriate antioxidant.For highly unstable materials,it may benecessary to use alternative techniques as an indication of ﬂow charac-teristics.9.9For materials with ﬂow rates greater than 10g/10min,a weight (and if needed,a piston)support must be used afterthe initial purge.The support shall be removed at such a timeas to allow the test to begin within 760.5min of thecompletion of the charge.The piston/weight support should beof such a length that the lower scribe mark of the supportedpiston/weight will be 25mm above the top of the guidebushing or other suitable reference mark.N OTE 21—It has been found that the effect of choosing plugging,weight support,or both,is signiﬁcant to the ﬂow rate results.The choiceof piston support was made to cover all conditions and ﬂow rates 10to 50g/10min.9.10For all tests,start collecting a timed extrudate whenrequirements for the piston position are met,provided this iswithin 7.060.5min from the end of charging;otherwise,discard the charge and repeat the test with readjusted pistonposition after the initial purge,or change weights.Require-ments are that the top scribed mark on the piston be visibleabove the cylinder or index and that the lower scribe mark bein the cylinder or below the index.As the lower scribed markapproaches the top of the cylinder or index,reset the timer tozero,then simultaneously start the timer and make the initialcut-off when the position requirements are met.Make the ﬁnal cut-off exactly when the time interval given in Table 2is reached.Collect the timed extrudate.If the extrudate contains visible bubbles,discard the complete charge and begin the test again.N OTE 22—The charge weight should only be increased if no material is being purged and there is still not enough material to complete the test.9.11Discharge the remainder of the specimen and push the die out through the top of the cylinder.Swab out the cylinder with cloth patches after the manner of cleaning a pistol barrel.The die may be cleaned by dissolving the residue in a solvent.A better method is pyrolytic decomposition of the residue in a nitrogen atmosphere.Place the die in a tubular combustion furnace or other device for heating to 550610°C and clean with a small nitrogen purge through the die.This method is preferable to ﬂame or solvent cleaning,being faster than solvent cleaning and less detrimental to the die than an open ﬂame.In certain cases where materials of a given class having similar ﬂow characteristics are being tested consecutively,interim die cleaning may be unnecessary.In such cases,however,the effect of cleaning upon ﬂow rate determination must be shown to be negligible if this step is avoided.9.12Once the extrudate is cool,weigh to the nearest 1mg.9.13Multiply the weight of the extrudate by the appropriate factor shown in Table 2to obtain the ﬂow rate in grams per 10min.N OTE 23—Frequently,errors in test technique,apparatus geometry,or test conditions,which defy all but the most careful scrutiny exist,causing discrepancy in ﬂow rate determinations.The existence of such errors is readily determined by periodically measuring a reference sample of known ﬂow rate.The ﬂow rate value and range to be tolerated can be determined using a statistically correct test program composed of multiple determinations with various instruments.Standard samples of polyethyl-ene,linear or branched,are available from the National Institute of Standards and Technology.9.14In case a specimen has a ﬂow rate at the borderline of the ranges in Table 2and slightly different values are obtained at different time intervals,the referee value shall be obtained at the longer time interval.10.Procedure B—Automatically Timed Flow Rate Measurement 10.1Apparatus :10.1.1Extrusion plastometer and auxiliary equipment are detailed in Section 4and below.10.1.2A timing device shall electrically,optically,or me-chanically time piston movement within the speciﬁed travel range.The requirements of the system are as follows:10.1.2.1Sense and indicate the piston travel time within 60.01s (see Note 1).10.1.2.2Measure piston travel within 60.4%of the nomi-nal preset value (see 10.1.2.4and 10.1.2.5)for use in the ﬂow rate calculations.10.1.2.3Any effects on the applied load must be included in the allowable tolerance given in 5.4.3.10.1.2.4It should be preset or be settable for measuring piston travel of 6.3560.25mm for ﬂow rates up to 10g/10min.10.1.2.5It should be preset or be adjustable for measuringTABLE 2Standard Test Conditions,Sample Mass,A and TestingTime BFlow Range,g/10min Suggested Mass of Sample in Cylinder,g Time Inter-val,min Factor forObtaining FlowRate in g/10min0.15to 1.0 2.5to 3.0 6.00 1.67>1.0to 3.5 3.0to 5.0 3.00 3.33>3.5to 10 4.0to 8.0 1.0010.00>10to 25 4.0to 8.00.5020.00>25 4.0to 8.00.2540.00A This is a suggested mass for materials with melt densities of about 0.7g/cm 3.Correspondingly,greater quantities are suggested for materials of greater meltdensities.Density of the molten resin (without ﬁller)may be obtained using theprocedure described by Terry,B.W.,and Yang,K.,“A New Method for DeterminingMelt Density as a Function of Pressure and Temperature,”SPE Journal ,SPEJA,Vol.20,No.6,June 1964,p.540or the procedure described by Zoller,Paul,“ThePressure-Volume-Temperature Properties of Polyoleﬁns,”Journal of Applied Poly-mer Science ,Vol 23,1979,p.1051.It may also be obtained from the weight of anextruded known volume of resin at the desired temperature.For example,25.4mm(1in.)of piston movement extrudes 1.804cm 3of resin.An estimate of the densityof the material can be calculated from the following equation:resin density at test temperature 5M /1.804where:M 5mass of extruded resin.B See9.14.piston travel of 25.460.25mm for ﬂow rates greater than 10g/10min.10.1.2.6To ensure high interlaboratory reproducibility,it isimportant that the timing device operates within a ﬁxed portionof the cylinder.This is deﬁned as the portion of the cylinderbetween 4662mm and 20.662mm above the top of the die.10.1.2.7Check die,cylinder,and position dimensions forconformance to 5.2-5.4and Figs.1and 2.10.2Procedure :10.2.1Refer to Table 1for selection of conditions oftemperature and load in accordance with the material speciﬁ-cation.10.2.2Check the die bore diameter with appropriately sizedno-go/go gages prior to testing.Make frequent checks todetermine whether the die diameter (tested with die at2365°C)is within the tolerances given in 5.3(see Note 15).10.2.3Ensure that the bore of the extrusion plastometer isproperly aligned in the vertical direction (see Appendix X1).10.2.4Inspect the apparatus and die for cleanliness.If it isnot clean,see 9.11and Note 14.10.2.5Check the die bore diameter with appropriately sizedno-go/go gages before beginning the test.Make frequentchecks to determine whether the die diameter is within thetolerances given in 5.3(see Note 15).10.2.6Verify that the temperature is stable and within60.2°C of the appropriate test temperature as speciﬁed in5.5.1.10.2.7Insert the die and the piston.The temperature of thecylinder with the piston and die in place must be stable at theappropriate test temperature 15min before testing is begun.When equipment is used repetitiously,it should not be neces-sary to heat the piston and die for 15min.10.2.8Adjust the travel arm to 6.3560.25mm for mea-suring materials with expected ﬂow rates of up to 10g/10minor 25.4060.25mm for measuring materials with expectedﬂow rates of 10g/10min or higher.N OTE 24—It has been found that for some materials the melt ﬂow ratesobtained on a material will be different depending on which timer lengthis chosen;therefore,it is important to adhere to the protocol in 10.2.8tocompare interlaboratory results.10.2.9Remove the piston and place it on an insulatedsurface.Charge the cylinder within 60s with a weightedportion of the sample according to the expected ﬂow rate,asgiven in Table 2.Reinsert the piston and add weight.10.2.10Allow time for the material to soften and begin tomelt,and then purge some material to a position such thatsubsequent travel of the piston will position the lower scribe mark at the reference start position 7.060.5min from the completion of the charge.Purge must be completed at least 2min prior to start of the test for materials having melt ﬂow rates less than 10g/10min (see Note 18).10.2.11Weight and piston support,if needed,must be used after the initial purge.The support will be removed at such a time as to allow the timer to activate within 7.060.5min after completion of the charge.If the timer is not activated within 760.5min after the completion of the charge,the test must be repeated with readjusted piston position after the initial purge,or change weights.The piston/weight support should be of such a length that the lower scribe mark of the supported piston/weight will be at least 25mm above the top of the cylinder.Only use piston support if there is excessive material ﬂow (see Notes 21and 22).10.2.12For materials greater than 50g/10min a die plug must be used in addition to the piston/weight support.The die plug is inserted before charge and is removed prior to removing the piston/weight support.The initial charge should be adjusted to reduce excess ﬂow.If the timer arm is not activated within 760.5min after the completion of the charge the test must be repeated with readjusted piston position,or change weights (see Notes 21and 22).N OTE 25—Warning:Rapid expulsion of material when die plug is removed may be hazardous.10.2.13If the timed extrudate contains visible bubbles,repeat the test (see Note 23).10.2.14Record the time to the nearest 0.01s for the piston to complete the calibrated distance of travel.10.2.15Discharge any remaining resin and clean the die,piston,and cylinder as detailed in 9.11.11.Calculation (Procedure B)11.1Calculate the ﬂow rate in grams per 10min or volume rate in cm 3per 10min as follows (see Note 23):Flow rate 5~4263L 3d !/t or V olume rate 54263L /t where:L 5length of calibrated piston travel,cm,d 5density of resin at test temperature,g/cm 3(see refer-ence under Table 2),t 5time of piston travel for length L,s,and 4265mean of areas of piston and cylinder 3600.N OTE 26—Factors that may be substituted in the following equation are given for some materials in Table 3.Flow rate,g/10min 5F /t where:F 5factor from Table 3,and t 5time of piston travel for length L,s.11.2Agreement between Procedures A and B may be optimized if an average melt density for a particular type of material is determined with the actual equipment used and that value is substituted into the equation given in 11.1.TABLE 3Factors for Calculation of Flow RateMaterial (Unpigmented)Tempera-ture,°C Piston Travel,L ,cm (in.)Factor forCalculation of FlowRate,F APolyethylene 190 2.54(1)826Polyethylene 1900.635(0.25)207Polypropylene 230 2.54(1)799Polypropylene 2300.635(0.25)200A Factors calculated using melt-density values of 0.7636g/cm 3for polyethyleneand 0.7386g/cm 3for polypropylene,as expressed in article by Zoller,Paul,“ThePressure-Volume-Temperature Properties of Polyoleﬁns,”Journal of Applied Poly-mer Science ,Vol 23,1979,P .1051.The base densities at 23°C for which the meltdensities are reported were 0.917g/dm 3for annealed low-density polyethyleneand polypropylenehomopolymer.。

天波超视距雷达非均匀采样信号频谱重构

第４６卷　第４期２０２４年４月系统工程与电子技术ＳｙｓｔｅｍｓＥｎｇｉｎｅｅｒｉｎｇａｎｄＥｌｅｃｔｒｏｎｉｃｓＶｏｌ．４６　Ｎｏ．４Ａｐｒｉｌ２０２４文章编号：１００１５０６Ｘ（２０２４）０４１２３６１１　网址：ｗｗｗ．ｓｙｓｅｌｅ．ｃｏｍ收稿日期：２０２２１２０６；修回日期：２０２３０４２６；网络优先出版日期：２０２３０７２５。

网络优先出版地址：ｈｔｔｐ：∥ｋｎｓ．ｃｎｋｉ．ｎｅｔ／ｋｃｍｓ／ｄｅｔａｉｌ／１１．２４２２．ＴＮ．２０２３０７２５．１８０７．００２．ｈｔｍｌ通讯作者．引用格式：陈子睿，陈阿磊，刘维建，等．天波超视距雷达非均匀采样信号频谱重构［Ｊ］．系统工程与电子技术，２０２４，４６（４）：１２３６１２４６．犚犲犳犲狉犲狀犮犲犳狅狉犿犪狋：ＣＨＥＮＺＲ，ＣＨＥＮＡＬ，ＬＩＵＷＪ，ｅｔａｌ．Ｓｐｅｃｔｒｕｍｒｅｃｏｎｓｔｒｕｃｔｉｏｎｏｆｎｏｎｕｎｉｆｏｒｍｌｙｓａｍｐｌｅｄｓｉｇｎａｌｓｆｏｒｏｖｅｒｔｈｅｈｏｒｉｚｏｎｒａｄａｒ［Ｊ］．ＳｙｓｔｅｍｓＥｎｇｉｎｅｅｒｉｎｇａｎｄＥｌｅｃｔｒｏｎｉｃｓ，２０２４，４６（４）：１２３６１２４６．天波超视距雷达非均匀采样信号频谱重构陈子睿，陈阿磊，刘维建，杨　军，陈文峰，马晓岩（空军预警学院，湖北武汉４３００１９）摘　要：受瞬态干扰影响和空海同时探测的需求，在长相参积累时间条件下，天波超视距雷达（ｏｖｅｒｔｈｅｈｏｒｉｚｏｎｒａｄａｒ，ＯＴＨＲ）回波信号的有效采样点往往缺损且非均匀，严重影响目标检测性能。

针对此问题，提出了一种基于压缩感知的ＯＴＨＲ频谱重构方法。

首先，建立了ＯＴＨＲ频域信号的稀疏模型；然后，提出了快速自适应复近似消息传递（ｆａｓｔａｄａｐｔｉｖｅｃｏｍｐｌｅｘａｐｐｒｏｘｉｍａｔｅｍｅｓｓａｇｅｐａｓｓｉｎｇ，ＦＡＣＡＭＰ）频谱重构算法并给出了算法实现步骤；最后，利用ＦＡＣＡＭＰ算法实现了ＯＴＨＲ频谱重构并分析了重构性能。

Fiber_Bragg_grating(FBG)-光纤光栅,chirp

Figure 1: A Fiber Bragg Grating structure, with refractive index profile and spectral responseFiber Bragg gratingFrom Wikipedia, the free encyclopediaA fiber Bragg grating (FBG ) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates awavelength specific dielectric mirror. A fiber Bragg grating can therefore be used as an inline optical filter to block certain wavelengths, or as a wavelength-specific reflector.Contents■1History■2Manufacture■2.1Interference■2.2Photomask■2.3Point-by-point■2.4Production■3Theory■4Types of gratings■4.1Standard, ortype I, gratings■4.2Type IAgratings■4.3Type IIA, ortype In, gratings■4.4Regeneratedgratings■4.5Type IIgratings■5Grating structure■5.1Apodizedgratings■5.2Chirped fiberBragg gratings■5.3Tilted fiberBragg gratings■5.4Long-periodgratings■6Applications■6.1Communications■6.2Fiber Bragggrating sensors■6.3Fiber bragggratings used infiber lasers■7See also■8References■9External linksHistoryThe first in-fiber Bragg grating was demonstrated by Ken Hill in 1978.[1]Initially, the gratings were fabricated using a visible laser propagating along the fiber core. In 1989, Gerald Meltz and colleagues demonstrated the much more flexible transverse holographic inscription technique where the laser illumination came from the side of the fiber. This technique uses the interference pattern of ultraviolet laser light[2]to create the periodic structure of the fiber Bragg grating. ManufactureFiber Bragg gratings are created by "inscribing" or "writing" systematic (periodic or aperiodic) variation of refractive index into the core of a special type of optical fiber using an intense ultraviolet (UV) source such as a UV laser. Two main processes are used: interference and masking. The method that is preferable depends on the type of grating to be manufactured. Normally a germanium-doped silica fiber is used in the manufacture of fiber Bragg gratings. The germanium-doped fiber is photosensitive, which means that the refractive index of the core changes with exposure to UV light. The amount of the change depends on the intensity and duration of the exposure as well as the photosensitivity of the fibre. To write a high reflectivity fiber Bragg grating directly in the fiber the level of doping with germanium needs to be high. However, standard fibers can be used if the photosensitivity is enhanced by pre-soaking the fiber in hydrogen. More recently, fiber Bragg gratings have also been written in polymer fibers, this is described in the PHOSFOS entry.[3] InterferenceThis was the first method used widely for the fabrication of fiber Bragg gratings and uses two-beam interference. Here the UV laser is split into two beams which interfere with each other creating a periodic intensity distribution along the interference pattern. The refractive index of the photosensitive fiber changes according to the intensity of light that it is exposed to. This method allows for quick and easy changes to the Bragg wavelength, which is directly related to the interference period and a function of the incident angle of the laser light.PhotomaskA photomask having the intended grating features may also be used in the manufacture of fiber Bragg gratings. The photomask is placed between the UV light source and the photosensitive fiber. The shadow of the photomask then determines the grating structure based on the transmitted intensity of light striking the fiber. Photomasks are specifically used in the manufacture of chirped Fiber Bragg gratings, which cannot be manufactured using an interference pattern.Point-by-pointA single UV laser beam may also be used to 'write' the grating into the fiber point-by-point. Here, the laser has a narrow beam that is equal to the grating period. This method is specifically applicable to the fabrication of long period fiber gratings. Point-by-point is also used in the fabrication of tilted gratings.ProductionFigure 2: FBGs reflected power as a function of wavelength Originally, the manufacture of the photosensitive optical fiber and the 'writing' of the fiber Bragg grating were done separately. Today, production lines typically draw the fiber from the preform and 'write' the grating, all in a single stage. As well as reducing associated costs and time, this also enables the mass production of fiber Bragg gratings. Mass production is in particular facilitating applications in smart structures utilizing large numbers (3000) of embedded fiber Bragg gratings along a single length of fiber.TheoryThe fundamental principlebehind the operation of a FBG, isFresnel reflection. Where lighttraveling between media ofdifferent refractive indices mayboth reflect and refract at theinterface.The refractive index willtypically alternate over a definedlength. The reflected wavelength (), called the Braggwavelength, is defined by therelationship,where is the effectiverefractive index of the grating in the fiber core and is the grating period. The effective refractive index quantifies the velocity of propagating light as compared to its velocity in vacuum. depends not only on the wavelength but also (for multimode waveguides) on the mode in which the light propagates. For this reason, it is also called modal index.The wavelength spacing between the first minima (nulls, see Fig. 2), or the bandwidth (), is (inthe strong grating limit) given by,where is the variation in the refractive index (), and is the fraction of power in the core. Note that this approximation does not apply to weak gratings where the grating length, , is not large compared to \ .The peak reflection () is approximately given by,where is the number of periodic variations. The full equation for the reflected power (), is given by,where,Types of gratingsThe term type in this context refers to the underlying photosensitivity mechanism by which grating fringes are produced in the fiber. The different methods of creating these fringes have a significant effect on physical attributes of the produced grating, particularly the temperature response and ability to withstand elevated temperatures. Thus far, five (or six) types of FBG have been reported with different underlying photosensitivity mechanisms.[4]These are summarized below:Standard, or type I, gratingsWritten in both hydrogenated and non-hydrogenated fiber of all types, type I gratings are usually known as standard gratings and are manufactured in fibers of all types under all hydrogenation conditions. Typically, the reflection spectra of a type I grating is equal to 1-T where T is the transmission spectra. This means that the reflection and transmission spectra are complementary and there is negligible loss of light by reflection into the cladding or by absorption. Type I gratings are the most commonly used of all grating types, and the only types of grating available off-the-shelf at the time of writing.Type IA gratings■Regenerated grating written after erasure of a type I grating in hydrogenated germanosilicate fiber of all typesType IA gratings were first observed in 2001[5]during experiments designed to determine the effects of hydrogen loading on the formation of IIA gratings in germanosilicate fiber. In contrast to the anticipated decrease (or 'blue shift') of the gratings' Bragg wavelength, a large increase (or 'red shift') was observed.Later work showed that the increase in Bragg wavelength began once an initial type I grating had reached peak reflectivity and begun to weaken. For this reason, it was labeled as a regenerated grating.Determination of the type IA gratings' temperature coefficient showed that it was lower than a standard grating written under similar conditions.The key difference between the inscriprion of type IA and IIA gratings is that IA gratings are written in hydrogenated fibres, whereas type IIA gratings are written in non-hydrogenated fibres.[6][7]Type IIA, or type In, gratings■These are gratings that form as the negative part of the induced index change overtakes the positive part. It is usually associated with gradual relaxation of induced stress along the axis and/or at the interface. It has been proposed that these gratings could be relabeled type In (for type 1 gratings with a negative index change; type II label could be reserved for those that are distinctly made above the damage threshold of the glass).[8]Later research by Xie et al. showed the existence of another type of grating with similar thermal stability properties to the type II grating. This grating exhibited a negative change in the mean index of the fiber and was termed type IIA. The gratings were formed in germanosilicate fibers with pulses from a frequency doubled XeCl pumped dye laser. It was shown that initial exposure formed a standard (type I) grating within the fiber which underwent a small red shift before being erased. Further exposure showed that a grating reformed which underwent a steady blue shift whilst growing in strength.[9][10]Regenerated gratingsThese are gratings that are reborn at higher temperatures after erasure of gratings, usually type I gratings and usually, though not always, in the presence of hydrogen. They have been interpreted in different ways including dopant diffusion (oxygen being the most popular current interpretation) and glass structural change. Recent work has shown that there exists a regeneration regime beyond diffusion where gratings can be made to operate at temperatures in excess of 1,295 °C, outperforming even type II femtosecond gratings.[11]These are extremely attractive for ultra high temperature applications.Type II gratings■Damage written gratings inscribed by multiphoton excitation with higher intensity lasers that exceed the damage threshold of the glass. Lasers employed are usually pulsed in order to reach these intensities. They include recent developments in multiphoton excitation usingfemtosecond pulses where the short timescales (commensurate on a timescale similar to local relaxation times) offer unprecedented spatial localization of the induced change. Theamorphous network of the glass is usually transformed via a different ionization and melting pathway to give either higher index changes or create, through micro-explosions, voidssurrounded by more dense glass.Archambault et al. showed that it was possible to inscribe gratings of ~100% (>99.8%) reflectance with a single UV pulse in fibers on the draw tower. The resulting gratings were shown to be stable at temperatures as high as 800 °C (up to 1,000 °C in some cases, and higher with femtosecond laser inscription). The gratings were inscribed using a single 40 mJ pulse from an excimer laser at 248 nm. It was further shown that a sharp threshold was evident at ~30 mJ; above this level the index modulation increased by more than two orders of magnitude, whereas below 30 mJ the index modulation grew linearly with pulse energy. For ease of identification, and in recognition of the distinct differences in thermal stability, they labeled gratings fabricated below the threshold as type I gratings and above the threshold as type II gratings. Microscopic examination of these gratings showed a periodic damage track at the grating’s site within the fiber [10]; hence type II gratings are also known as damage gratings. However, these cracks can be very localized so as to not play a major role in scattering loss if properly prepared [12][13]Grating structureFigure 3: Structure of the refractive index change in a uniform FBG (1), a chirped FBG (2), a tilted FBG(3), and a superstructure FBG (4).Figure 4: Refractive index profile in the core of, 1) a uniform positive-only FBG, 2) a Gaussian-apodized FBG, 3) a raised-cosine-apodized FBG with zero-dc change, and 4) a discrete phase shift FBG.The structure of the FBG can vary via therefractive index, or the grating period. Thegrating period can be uniform or graded, andeither localised or distributed in a superstructure.The refractive index has two primarycharacteristics, the refractive index profile, andthe offset. Typically, the refractive index profilecan be uniform or apodized, and the refractiveindex offset is positive or zero.There are six common structures for FBGs;[14]1.uniform positive-only index change,2.Gaussian apodized,3.raised-cosine apodized,4.chirped,5.discrete phase shift, and 6.superstructure.The first complex grating was made by J.Canning in 1994.[15][citation needed ]This supportedthe development of the first distributed feedback(DFB) fiber lasers, and also laid the groundworkfor most complex gratings that followed,including the sampled gratings first made byPeter Hill and colleagues in Australia.[citation needed ]Apodized gratingsThere are basically two quantities that controlthe properties of the FBG. These are the grating length,, given as and the grating strength, . There are,however, three properties that need to be controlled in a FBG. These are the reflectivity, the bandwidth, and the side-lobe strength. As shown above, in the strong grating limit (i.e., for large ) the bandwidth depends on the gratingstrength, and not the grating length. This meansthe grating strength can be used to set the bandwidth. The grating length, effectively , can then be used to set the peak reflectivity, which depends on both the grating strength and the grating length. The result of this is that the side-lobe strength cannot be controlled, and this simple optimisation results in significant side-lobes. A third quantity can be varied to help with side-lobe suppression. This is apodization of the refractive index change. The term apodization refers to the grading of the refractive index to approach zero at the endFigure 5: Optical add-drop multiplexer.of the grating. Apodized gratings offer significant improvement in side-lobe suppression whilemaintaining reflectivity and a narrow bandwidth. The two functions typically used to apodize a FBG are Gaussian and raised-cosine.Chirped fiber Bragg gratingsThe refractive index profile of the grating may be modified to add other features, such as a linear variation in the grating period, called a chirp. The reflected wavelength changes with the grating period, broadening the reflected spectrum. A grating possessing a chirp has the property of adding dispersion—namely, different wavelengths reflected from the grating will be subject to different delays. This property has been used in the development of phased-array antenna systems and polarization mode dispersion compensation, as well.Tilted fiber Bragg gratingsIn standard FBGs, the grading or variation of the refractive index is along the length of the fiber (the optical axis), and is typically uniform across the width of the fiber. In a tilted FBG (TFBG), the variation of the refractive index is at an angle to the optical axis. The angle of tilt in a TFBG has an effect on the reflected wavelength, and bandwidth.Long-period gratingsTypically the grating period is the same size as the Bragg wavelength, as shown above. For a grating that reflects at 1,500 nm, the grating period is 500 nm, using a refractive index of 1.5. Longerperiods can be used to achieve much broader responses than are possible with a standard FBG. These gratings are called long-period fiber grating. They typically have grating periods on the order of 100 micrometers, to a millimeter, and are therefore much easier to manufacture.ApplicationsCommunicationsThe primary application of fiberBragg gratings is in opticalcommunications systems. Theyare specifically used as notchfilters. They are also used inoptical multiplexers anddemultiplexers with an opticalcirculator, or optical add-dropmultiplexer (OADM). Figure 5 shows 4 channels, depicted as 4colours, impinging onto a FBGvia an optical circulator. The FBG is set to reflect one of the channels, here channel 4. The signal is reflected back to the circulator where it is directed down and dropped out of the system. Since the channel has been dropped, another signal on that channel can be added at the same point in the network.A demultiplexer can be achieved by cascading multiple drop sections of the OADM, where each drop element uses an FBG set to the wavelength to be demultiplexed. Conversely, a multiplexer can be achieved by cascading multiple add sections of the OADM. FBG demultiplexers and OADMs can also be tunable. In a tunable demultiplexer or OADM, the Bragg wavelength of the FBG can be tuned by strain applied by a piezoelectric transducer. The sensitivity of a FBG to strain is discussed below in fiber Bragg grating sensors.Fiber Bragg grating sensorsAs well as being sensitive to strain, the Bragg wavelength is also sensitive to temperature. This means that fiber Bragg gratings can be used as sensing elements in optical fiber sensors. In a FBG sensor, the measurand causes a shift in the Bragg wavelength, . The relative shift in the Bragg wavelength, , due to an applied strain () and a change in temperature () is approximately given by,or,Here, is the coefficient of strain, which is related to the strain optic coefficient. Also, is thecoefficient of temperature, which is made up of the thermal expansion coefficient of the optical fiber, , and the thermo-optic coefficient, .[16]Fiber Bragg gratings can then be used as direct sensing elements for strain and temperature. They can also be used as transduction elements, converting the output of another sensor, which generates a strain or temperature change from the measurand, for example fiber Bragg grating gas sensors use an absorbent coating, which in the presence of a gas expands generating a strain, which is measurable by the grating. Technically, the absorbent material is the sensing element, converting the amount of gas to a strain. The Bragg grating then transduces the strain to the change in wavelength. Specifically, fiber Bragg gratings are finding uses in instrumentation applications such as seismology,[17]pressure sensors for extremely harsh environments, and as downhole sensors in oil and gas wells for measurement of the effects of external pressure, temperature, seismic vibrations and inline flow measurement. As such they offer a significant advantage over traditional electronic gauges used for these applications in that they are less sensitive to vibration or heat and consequently are far more reliable. In the 1990s, investigations were conducted for measuring strain and temperature in composite materials for aircraft and helicopter structures.[18][19]Fiber bragg gratings used in fiber lasersRecently the development of high power fiber lasers has generated a new set of applications for fiber Bragg gratings (FBG’s), operating at power levels that were previously thought impossible. In the case of a simple fiber laser, the FBG’s can be used as the high reflector (HR) and output coupler (OC) to form the laser cavity. The gain for the laser is provided by a length of rare earth dopedoptical fiber, with the most common form using Yb3+ ions as the active lasing ion in the silica fiber. These Yb-doped fiber lasers first operated at the 1 kW CW power level in 2004 [20]based on free space cavities but were not shown to operate with fiber Bragg grating cavities until much later.[21] Such monolithic, all-fiber devices are produced by many companies worldwide and at power levels exceeding 1 kW. The major advantage of these all fiber systems, where the free space mirrors are replaced with a pair of fiber Bragg gratings (FBG’s), is the elimination of realignment during the life of the system, since the FBG is spliced directly to the doped fiber and never needs adjusting. The challenge is to operate these monolithic cavities at the kW CW power level in large mode area (LMA) fibers such as 20/400 (20 um diameter core and 400 um diameter inner cladding) without premature failures at the intra-cavity splice points and the gratings. Once optimized, these monolithic cavities do not need realignment during the life of the device, removing any cleaning and degradation of fiber surface from the maintenance schedule of the laser. However, the packaging and optimization of the splices and FBGs themselves are non-trivial at these power levels as are the matching of the various fibers, since the composition of the Yb-doped fiber and various passive and photosensitive fibers needs to be carefully matched across the entire fiber laser chain. Although the power handling capability of the fiber itself far exceeds this level, and is possibly as high as >30 kW CW, the practical limit is much lower due to component reliability and splice losses.[22]See also■Bragg's law■Diffraction■Diffraction grating■Dielectric mirror■Hydrogen sensor■Long-period fiber grating■Photonic crystal fiber■Distributed temperature sensing by fiber optics■PHOSFOS project -embedding FBGs in flexible skinsReferences1.^Hill, K.O.; Fujii, Y.; Johnson, D. C.; Kawasaki, B. S. (1978). "Photosensitivity in optical fiberwaveguides: application to reflection fiber fabrication". Appl. Phys. Lett.32(10): 647.Bibcode:1978ApPhL..32..647H(/abs/1978ApPhL..32..647H).doi:10.1063/1.89881(/10.1063%2F1.89881).2.^Meltz, G.; et al.(1989). "Formation of Bragg gratings in optical fibers by a transverse holographicmethod". Opt. Lett.14(15): 823. Bibcode:1989OptL...14..823M(/abs/1989OptL...14..823M). doi:10.1364/OL.14.000823(/10.1364%2FOL.14.000823). PMID19752980(///pubmed/19752980).3.^http://www.phosfos.eu/eng/Phosfos/Journals/Bragg-grating-in-polymer-optical-fibre-for-strain-bend-and-temperature-sensing4.^J. Canning, Fiber Gratings and Devices for Sensors and Lasers, Lasers and Photonics Reviews, 2 (4),275-289, Wiley, USA (2008)5.^Liu, Y. (2001). Advanced fiber gratings and their application. Ph.D. Thesis, Aston University.6.^Simpson, A. G. (2005). Optical Fibre Sensors and Their Interrogationdv. Ph.D. Thesis, AstonUniversity.7.^Simpson, A. G.; Kalli, K.; Zhou, K.; Zhang, L.; Bennion, I. (2003). "A method for the fabrication oftemperature compensating IA-I strain sensors". OFS16. Nara, Japan. pp. postdeadline paper PD4.8.^For a contemporary review, see J. Canning, Fiber Gratings and Devices for Sensors and Lasers, Lasersand Photonics Reviews, 2 (4), 275-289, Wiley, USA (2008)9.^Xie, W. X.; Niay, P.; Bernage, P.; Douay, M.; Bayon, J. F.; Georges, T.; Monerie, M.; Poumellec, B.(1993). "Experimental-Evidence of 2 Types of Photorefractive Effects Occurring During Photoinscriptions of Bragg Gratings Within Germanosilicate Fibres". Optics Communications104(1-3): 185–195. Bibcode:1993OptCo.104..185X(/abs/1993OptCo.104..185X).doi:10.1016/0030-4018(93)90127-Q(/10.1016%2F0030-4018%2893%2990127-Q). 10.^Niay, P.; Bernage, P.; Legoubin, S.; Douay, M.; Xie, W. X.; Bayon, J. F.; Georges, T.; Monerie, M.;Poumellec, B. (1994). "Behaviour of Spectral Transmissions of Bragg Gratings Written in Germania-Doped Fibres -Writing and Erasing Experiments Using Pulsed or CW UV Exposure". OpticsCommunications113(1-3): 176–192. Bibcode:1994OptCo.113..176N(/abs/1994OptCo.113..176N). doi:10.1016/0030-4018(94)90606-8(/10.1016%2F0030-4018%2894%2990606-8).11.^J. Canning, M. Stevenson, S. Bandyopadhyay, K. Cook, “Extreme silica optical fibre gratings”,Sensors, 8, pp.1-5, (2008)12.^Dong, L.; Archambault, J. L.; Reekie, L.; Russell, P. S. J.; Payne, D. N. (1993). "Single-Pulse BraggGratings Written During Fibre Drawing". Electronics Letters29(17): 1577–1578.doi:10.1049/el:19931051(/10.1049%2Fel%3A19931051).13.^Archambault, J. L.; Reekie, L.; Russell, P. S. J. (1993). "100-Percent Reflectivity Bragg ReflectorsProduced in Optical Fibres By Single Excimer-Laser Pulses". Electronics Letters29(5): 453–455.doi:10.1049/el:19930303(/10.1049%2Fel%3A19930303).14.^Erdogan, Turan (August 1997). "Fiber Grating Spectra"(/xpl/freeabs_all.jsp?tp=&arnumber=618322&isnumber=13456). Journal of Lightwave Technology15(8): 1277–1294.Bibcode:1997JLwT...15.1277E(/abs/1997JLwT...15.1277E).doi:10.1109/50.618322(/10.1109%2F50.618322).15.^J. Canning, M. G. Sceats, "p-phase-shifted periodic distributed structures in germanosilicate fibre byUV post-processing", Electron. Lett., 30, (16), 1344-1345, (1994)16.^Othonos, Andreas; Kalli, Kyriacos (1999). Fiber Bragg Gratings: Fundamentals and Applications inTelecommunications and Sensing. Artech House. ISBN0-89006-344-3.17.^P. Ferraro; G. De Natale (2002). "On the possible use of optical fiber Bragg gratings as strain sensorsfor geodynamical monitoring". Optics and Lasers in Engineering37(2-3): 115–130.Bibcode:2002OptLE..37..115F(/abs/2002OptLE..37..115F). doi:10.1016/S0143 -8166(01)00141-5(/10.1016%2FS0143-8166%2801%2900141-5).18.^US patent 5493390(/textdoc?DB=EPODOC&IDX=US5493390),"Integrated optical instrumentation for the diagnostics of parts by embedded or surface attached optical sensors", issued Feb. 20, 199619.^US patent 5399854(/textdoc?DB=EPODOC&IDX=US5399854), J.R.Dunphy & et al., "Embedded optical sensor capable of strain and temperature measurement using asingle diffraction grating", issued March 21, 199520.^Jeong, Y., Sahu, J.K., Payne,D.N. and Nilsson., J., “Ytterbium-doped large-core fiber laser with 1kWcontinuous-wave output power”, Electronics Letters, 40: 470-472, 200421.^2. Xiao, Y., Brunet, F., Kanskar, M., Faucher, M., Wetter, A., and Holehouse, N., “1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks”, Optics Express, 20: 3296-3301, 2012.22.^3. Dawson, J.W., Messerly, M.J., Beach, R.J., Shverdin, M.Y., Stappaerts, E.A., Sridharan, A.K., Pax,P.H., Heebner, J.E., Siders, C.W. and Barty, C.J.P.,“Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power” Optics Express, 16: 13240-13260, 2008External linksInternational Optical Sensor Societies■FOSNE(/index.php?option=com_content&view=category&id=11&Itemid=14)-Fibre Optic Sensing NetworkEuropeDevelopment Platforms■TFT (http://www.tft-fos.nl)-Technobis Fibre TechnologiesOther■Bragg grating as hydrogen detector (http://bit.or.at/irca/bbsshow8.php?ref1=OO/INTA/36&vQuelle=&bcc=)■/patent/7133582.html -Fiber -Optic filter with tunable grating Retrieved from "/w/index.php?title=Fiber_Bragg_grating&oldid=554086706"Categories: Optical fiber Diffraction■This page was last modified on 8 May 2013 at 06:43.■Text is available under the Creative Commons Attribution-ShareAlike License;additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy.Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profitorganization.页码，11/11Fiber Bragg grating -Wikipedia, the free encyclopedia 2013/5/18/wiki/Fiber_Bragg_grating。

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A new method for sampled fiber Bragg grating fabrication by use of both femtosecond laser and CO2 laser
Xia Fang, X. Y. He, C. R. Liao, Minwei Yang, D. N. Wang*, Ying Wang
Received 4 Nov 2009; revised 19 Jan 2010; accepted 19 Jan 2010; published 25 Jan 2010
#119555 - $15.00 USD
(C) 2010 OSA
1 February 2010 / Vol. 18, No. 3 / OPTICS EXPRESS 2646
©2010 Optical Society of America
OCIS codes: (060.3735) Fiber Bragg gratings; (230.4000) Microstructure fabrication; (320.7140) Ultrafast processes in fibers; (140.7090) Ultrafast lasers.
References and links
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Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, P. R. China *eednwang@.hk
Abstract: A new method for sample fiber Bragg grating fabrication by use of both femtosecond laser and CO2 laser has been proposed and demonstrated. Such a method exhibits the advantages of high fabrication flexibility, and good thermal stability. The sampling period and duty cycle can be easily varied by changing the CO2 laser beam scanning pattern during operation. The gratings produced have potential applications in optical communications, fiber lasers, and optical fiber sensors.