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Double linear strain distribution assumption of RC beam strengthened with external-bonded or near-surface mounted fiber reinforced plastic 被引量:4
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作者 任振华 刘汉龙 周丰峻 《Journal of Central South University》 SCIE EI CAS 2012年第12期3582-3594,共13页
Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain... Rehabilitation of existing structures with fiber reinforced plastic(FRP)has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high specific stiffness.The strain coordination results of 34 reinforced concrete beams(four groups)strengthened with different methods were presented including external-bonded or near-surface mounted glass or carbon FRP or helical rib bar in order to study the strain coordination of the strengthening materials and steel rebar of RC beam.Because there is relative slipping between concrete and strengthening materials(SM),the strain of SM and steel rebar of RC beam satisfies the double linear strain distribution assumption,that is,the strain of longitudinal fiber parallel to the neutral axis of plated beam within the scope of effective height(h0)of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of SM and steel rebar satisfies the equation εGCH=βεsteel,where the value of β is equal to 1.1-1.3 according to the test results. 展开更多
关键词 double linear strain distribution assumption external-bonded structure near-surface mounted structure fiber reinforced plastic strengthening concrete beam
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Estimation of the Maximum Output Power of Double-Clad Photonic Crystal Fiber Laser 被引量:1
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作者 CHEN Yue-E WANG Yong QU Xi-Long 《Chinese Physics Letters》 SCIE CAS CSCD 2012年第7期146-148,共3页
Compared with traditional optical fiber lasers,double-clad photonic crystal fiber (PCF) lasers have larger surfacearea-to-volume ratios.With an increase of output power,thermal effects may severely restrict output pow... Compared with traditional optical fiber lasers,double-clad photonic crystal fiber (PCF) lasers have larger surfacearea-to-volume ratios.With an increase of output power,thermal effects may severely restrict output power and deteriorate beam quality of fiber lasers.We utilize the heat-conduction equations to estimate the maximum output power of a double-clad PCF laser under natural-convection,air-cooling,and water-cooling conditions in terms of a certain surface-volume heat ratio of the PCF.The thermal effects hence define an upper power limit of double-clad PCF lasers when scaling output power. 展开更多
关键词 fiber CRYSTAL double
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Amplified Spontaneous Emission in Single Frequency Double-Clad Fiber Power Amplifiers
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作者 杨苏辉 孙鑫鹏 +2 位作者 杨春香 赵长明 李卓 《Journal of Beijing Institute of Technology》 EI CAS 2008年第2期198-201,共4页
Amplified spontaneous emission (ASE) in diode laser pumped double-clad fiber power amplifiers is studied experimentally, The dependences of ASE on fiber length and cross section of active core are discussed and the ... Amplified spontaneous emission (ASE) in diode laser pumped double-clad fiber power amplifiers is studied experimentally, The dependences of ASE on fiber length and cross section of active core are discussed and the variations of ASE power as the function of pumping and signal power are investigated. There are indications that long fibers with large mode area need stronger input signals to suppress ASE. It is shown that a 150 mW input signal can suppress the ASE by 40 dB in a 4 m large mode area fiber, while to efficiently suppress the ASE in a 10 m fiber, stronger input signal is needed. 12.5 W and 16.1 W single frequency CW output power are obtained from 4 m fiber and 10 m fiber respectively. No stimulated Brillouin scattering (SBS) was observed 展开更多
关键词 fiber laser double cladding fiber single frequency power amplifier
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Double Clad Er-doped Fiber Amplifier
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作者 FU Yong-jun MAO Xiang-qiao WEI Huai LI jian 《Semiconductor Photonics and Technology》 CAS 2007年第4期289-293,共5页
Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have d... Presented is a theoretical study of double-clad Er-doped fiber power amplifier(EDFA). Two kinds of double clad fibers(DCF) with rectangular and "flower" inner clad shapes are studied, and these fibers have different coupling constants and propagation losses. We calculate the effective pump power absorption ratio along the fiber with different coupling constants from the first cladding to the doped core and with different propagation losses for the power in the inner cladding. Then the gains of the double clad Er-doped fiber amplifiers versus fiber lengths are calculated using the EDFA model based on propagation and rate equations of a homogeneous, two-level medium. 展开更多
关键词 double clad fiber(DCF) Er-doped fiber amplifier(EDFA) pump power absorption ration gain rate equations
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New Pyrometer with Double Y-type Optical Fibers
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作者 SHI Weidong, LI Zhiquan, TANG Xuhui, JIANG Wanlu(Yanshan University, Qinhuangdao 066004, CHN) 《Semiconductor Photonics and Technology》 CAS 1997年第1期40-43,49,共5页
Abstract: A new pyrometer, which can solve the affection of emissivity change in temperature measuring, has been developed by double Y - type optical fibers. The mathematical model of the new pyrometer is presented an... Abstract: A new pyrometer, which can solve the affection of emissivity change in temperature measuring, has been developed by double Y - type optical fibers. The mathematical model of the new pyrometer is presented and the errors of the new pyrometer are analyzed. 展开更多
关键词 EMISSIVITY double Y - type Optical fibers PYROMETER
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Absorption efficiency of graded-index double-clad fiber lasers
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作者 王子华 张辉 肖中银 《Journal of Shanghai University(English Edition)》 CAS 2006年第1期44-47,共4页
Absorption efficiency of graded-index double-clad fiber lasers or amplifiers is analyzed. As ray optics method is no longer valid for graded-index case, the mode analysis method is used. Calculated results show that a... Absorption efficiency of graded-index double-clad fiber lasers or amplifiers is analyzed. As ray optics method is no longer valid for graded-index case, the mode analysis method is used. Calculated results show that absorption efficiency for a graded-index is higher than that for a step-index in symmetric case. In offset core case, the graded-index can achieve the same absorption efficiency with much smaller offset distance. Absorption efficiencies for different graded-index profiles of the inner cladding are compared. 展开更多
关键词 pump absorption double-clad fibers graded-index multimode fibers.
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The Formation of Fringes of Equal Chromatic Order across Double Clad Fiber in the Presence of High Power Lasers
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作者 Mona F. Omar Rania H. Abd El-Maksoud 《Optics and Photonics Journal》 2016年第2期29-38,共10页
Multiple-beam fringes of equal chromatic order interferometry is a powerful technique to extract optical properties over a continuous range of spectrum. In this paper we develop a theory for the spectral shape of the ... Multiple-beam fringes of equal chromatic order interferometry is a powerful technique to extract optical properties over a continuous range of spectrum. In this paper we develop a theory for the spectral shape of the fringes of equal chromatic order (FECO) that are formed across a double-clad fiber. The modified single term Sellmeier dispersion formula is used to construct the refractive index dispersion curves for the liquid, claddings, and core. Expressions for the paraxial optical path length for several rays passing through the fiber and the liquid are developed. The condition of bright fringe is applied to get an analytical expression for the spectral shape of the FECO across a double-clad fiber with an elliptical/circular inner cladding. A potential application of this theory is to determine the dispersion of Kerr constant of the claddings and the core of the fiber. To illustrate the theory and its application, simulation examples are provided and discussed. 展开更多
关键词 INTERFERENCE Physical Optics DISPERSION Nonlinear Optics Fringes of Equal Chromatic Order double-Clad fibers
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抑光载波双边带Radio over Fiber双工通信系统设计 被引量:8
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作者 李广 黄旭光 《光子学报》 EI CAS CSCD 北大核心 2009年第5期1153-1157,共5页
提出并模拟证明了基于两个电光相位调制器实现抑光载波双边带(Radio on Fiber,RoF)双工传输系统设计方案.通过改变电光相位调制器的最大相偏量,实现了抑光载波双边带信号传输——使通信带宽加倍,而且很好地控制上下行传输信号的误码率.... 提出并模拟证明了基于两个电光相位调制器实现抑光载波双边带(Radio on Fiber,RoF)双工传输系统设计方案.通过改变电光相位调制器的最大相偏量,实现了抑光载波双边带信号传输——使通信带宽加倍,而且很好地控制上下行传输信号的误码率.仿真模拟结果表明,发射功率为3dBm的光信号在无放大、色散系数为20ps/(nm.km)、衰减系数为0.25dB/km的SMF-28单模光纤中传输时,其超高频RF调制信号的频率可达24GHz,数据码元传输速率可达2.5Gbit/s,传输距离40km以上. 展开更多
关键词 电光相位调制 抑光载波双边带调制 光学毫米波 ROF 无线通信网络
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Fabrication of arbitrarily apodized fiber Bragg gratings with narrow bandwidth
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作者 吕昌贵 恽斌峰 崔一平 《Journal of Southeast University(English Edition)》 EI CAS 2009年第1期23-25,共3页
A double-exposure fabrication method without any intensity shadow mask to fabricate arbitrarily apodized fiber Bragg gratings( FBGs) with narrow bandwidth is demonstrated by controlling the total ultra violet (UV)... A double-exposure fabrication method without any intensity shadow mask to fabricate arbitrarily apodized fiber Bragg gratings( FBGs) with narrow bandwidth is demonstrated by controlling the total ultra violet (UV) irradiation along the grating by varying the speed of a translation stage. The UV source used is a stable continuous intracavity frequency-doubled argonion laser. The parameters (such as length, apodization profile, average index change)of FBGs can be easily changed with this method. The total UV irradiation is kept constant in the doubleexposure process because of the precise control of the exposure time, which ensures that the apodized FBG's bandwidth can be extremely narrow. The full width at half maximum (FWHM) bandwidth of the 2-cm-long apodized FBG fabricated by this method is 0. 15 nm with a maximum reflectivity of more than 95%. 展开更多
关键词 fiber Bragg grating APODIZATION double exposure
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通过光电相位调制和光纤光栅滤波实现Radio over Fiber传输系统设计
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作者 李广 黄旭光 杨旭生 《华南师范大学学报(自然科学版)》 CAS 北大核心 2011年第4期67-70,共4页
提出并模拟证明了基于电光相位调制(PM)和布拉格光纤光栅(FBG)实现受抑光载波的双边带(DSBOCS,Double-Sideband with Optical Carrier Suppression)的双向Radio over Fiber(RoF)传输系统网络设计方案.激光光源置于中心站,载有信息的光... 提出并模拟证明了基于电光相位调制(PM)和布拉格光纤光栅(FBG)实现受抑光载波的双边带(DSBOCS,Double-Sideband with Optical Carrier Suppression)的双向Radio over Fiber(RoF)传输系统网络设计方案.激光光源置于中心站,载有信息的光信号通过光纤到达基站后经FBG分成两路,其中一路是被接收的下行信号,另一路作为上行信号调制后返回中心站.通过FBG,其下行信号不但实现了受抑光载波的双边带———使通信带宽加倍,上行信号作为光源通过电光强度调制,有效地实现信息的上载.仿真结果表明,光源发射功率为3 dBm,无光放大,在色散系数为20 ps/(nm.km),衰减系数为0.25 dB/km的单模光纤中传输,超高频RF信号的频率可达24 GHz,系统码元传输速率可达2.5 Gbit/s、传输距离50 km以上. 展开更多
关键词 电光相位调制 FBG 受抑光载波的双边带 光学毫米波 ROF 光纤通信系统 无线通信网络
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与真核生物DSBs修复有关的NHEJ途径研究进展 被引量:3
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作者 虞海燕 梁锋 杨志伟 《生物技术通报》 CAS CSCD 北大核心 2009年第10期55-59,共5页
DNA双链断裂是真核生物最严重的DNA损伤形式。如果断裂的DNA双链无法及时修复,将可能导致细胞死亡。非同源末端连接途径在真核生物DSBs修复中起重要作用。综述了真核生物NHEJ途径中核心蛋白质Ku、DNA-PKcs、DNA连接酶IV、XRCC4、ARTEMIS... DNA双链断裂是真核生物最严重的DNA损伤形式。如果断裂的DNA双链无法及时修复,将可能导致细胞死亡。非同源末端连接途径在真核生物DSBs修复中起重要作用。综述了真核生物NHEJ途径中核心蛋白质Ku、DNA-PKcs、DNA连接酶IV、XRCC4、ARTEMIS和XIF等因子的结构和功能,并简要介绍了NHEJ修复途径的分子机制,其中涉及到DSBs位点蛋白复合体组装的两种模型。 展开更多
关键词 DNA双链断裂(dsbs) 非同源重组连接 KU蛋白
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BRCA1与DSB修复路径取向 被引量:4
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作者 吴晓丹 刘江琴 李莉萍 《中国生物化学与分子生物学报》 CAS CSCD 北大核心 2015年第1期28-33,共6页
乳腺癌易感基因1(BRCA1)是一个肿瘤抑制基因.BRCA1参与DNA末端切除、细胞周期调控以及染色体修饰等来维护基因组的稳定性.有研究表明,它能够促进正确的DNA双链断裂(DSBs)修复,如同源重组修复(HDR)和经典的非同源末端连接(C-NHEJ);而抑... 乳腺癌易感基因1(BRCA1)是一个肿瘤抑制基因.BRCA1参与DNA末端切除、细胞周期调控以及染色体修饰等来维护基因组的稳定性.有研究表明,它能够促进正确的DNA双链断裂(DSBs)修复,如同源重组修复(HDR)和经典的非同源末端连接(C-NHEJ);而抑制错误性的DSB修复,如单链退火修复(SSA)和非经典的末端连接(A-EJ);其机制是通过与某些DNA修复相关蛋白质的相互作用来引导DSB修复.目前,BRCA1在DSB修复通路中的作用机制尚未完全明确,仍有待进一步的研究.本文主要阐述BRCA1在DSB各修复通路中是如何发挥其引导作用的. 展开更多
关键词 乳腺癌易感基因1 DNA双链断裂 同源重组 非同源末端连接
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The effect of fiber orientation on fracture response of metallic fiber-reinforced adhesive thin films 被引量:1
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作者 S.M.J.Razavi L.Sandnes +1 位作者 J.Torgersen F.Berto 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2018年第1期43-47,共5页
Incorporation of metallic fibers into the adhesive layer can significantly improve the mechanical behavior of the adhesive joint. This paper aims to assess the fracture behavior of an epoxy adhesive reinforced by long... Incorporation of metallic fibers into the adhesive layer can significantly improve the mechanical behavior of the adhesive joint. This paper aims to assess the fracture behavior of an epoxy adhesive reinforced by longitudinal and lateral metallic fibers. Double cantilever beam(DCB) specimens were used to obtain the fracture energy of both non-reinforced and reinforced adhesives under mode I loading condition. In addition to the fiber orientation, the distance between the metal fibers was considered as the second key parameter in the experiments. It was concluded that although incorporation of metallic fibers in the adhesive layer improves the fracture behavior of neat adhesive, however, higher improvements were observed for the adhesive reinforced with longitudinal fibers. Furthermore, reducing the fiber distances resulted in higher values of fracture energy. 展开更多
关键词 double CANTILEVER beam(DCB) FRACTURE energy Metal fibers THIN film Toughened ADHESIVE
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Experimental Research on Erbium-doped Superfluorescent Fiber Source 被引量:2
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作者 CHENSheng-ping LUKe-cheng LIYi-gang LIJia-fang ZHUJian-ping FENGMing LIJing 《Semiconductor Photonics and Technology》 CAS 2004年第2期122-126,共5页
The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The inf... The effects of the variations in fiber length,fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs).The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated.By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port,the pump power dependent on MWS becomes independent of pumped EDF length.This is a novel phenomenon that hasn’t been reported up to now,and should be helpful to SFS fabrication and theory analysis.By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ~20 channels (from 1 542 nm to 1 559 nm) is got.The MWFS has a channel spacing of ~0.8 nm which satisfies ITU-standard.The intensity fluctuation among channels is less than 0.5 dB,and the extinction ratio of all channels is above 14 dB.This kind of MWFS should be useful to wavelength division multiplexing systems. 展开更多
关键词 Superfluorescent fiber source Erbium-doped fiber double pass backward configuration Mean wavelength stability Multi-wavelength fiber source
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Double pull specimen more suitable for measuring bond-slip relationship of FRP-to-concrete interface 被引量:1
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作者 杨奇飞 陆小华 熊光晶 《Journal of Central South University》 SCIE EI CAS 2010年第2期400-405,共6页
A new "conceptual" design named "double pull" specimen was proposed in order to measure the bond-slip(δ-τ) relationship of fiber reinforced polymer(FRP)-to-concrete interface more accurately.A fi... A new "conceptual" design named "double pull" specimen was proposed in order to measure the bond-slip(δ-τ) relationship of fiber reinforced polymer(FRP)-to-concrete interface more accurately.A finite element analysis(FEA) was performed for preliminarily evaluating the suitability of the proposed conceptual double pull specimen.Through the FEA,it was indicated that the FRP-to-concrete interface of the proposed conceptual specimen might subject to a much higher load level than that of the most commonly used simple shear specimen,showing a great potential for measuring δ-τ relationship more accurately.In the light of the conceptual specimen,a kind of "practical" double pull specimen was developed and proved to be more suitable for measuring δ-τ relationship through an exploratory experimental study with 20 specimens.Consequently,an experimental program with 10 double pull specimens was performed for measuring the ultimate slip δu which was difficult to capture by using the existing specimens.It is shown that the range of δu is 0.31-0.52 mm based on the test results.The suggestion for improving the measure method is also put forward. 展开更多
关键词 fiber reinforced polymer (FRP) concrete BOND-SLIP ultimate slip double pull specimen EXTENSOMETER
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Liquid Level Measurement in Oil Tanks Based on Double-differential Pressure Technique 被引量:1
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作者 WEN Shu hui, DUAN Hui fang (School of Electr. Eng., Yanshan University, Qinhuangdao 066004, CHN) 《Semiconductor Photonics and Technology》 CAS 2001年第3期168-171,176,共5页
The system principle and configuration of the double differential pressure method for measuring oil tank level are presented. The fundamental method and circuit of fiber optic transmission are analyzed .The accuracy a... The system principle and configuration of the double differential pressure method for measuring oil tank level are presented. The fundamental method and circuit of fiber optic transmission are analyzed .The accuracy and security of level measurement in the oil tanks have been greatly improved. 展开更多
关键词 double differential pressure technique Level measurement fiber optic transmission
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Influence of double Rayleigh backscatter in CATV systems with Raman amplifiers
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作者 王春华 李力 +1 位作者 王佳世 范为杰 《Journal of Shanghai University(English Edition)》 CAS 2011年第1期49-53,共5页
The double Rayleigh backscatter (DRB) effect in long distance CATV systems using fiber Raman amplifiers (FRAs) is investigated theoretically in the paper. As a comparison, performance of a system with erbium doped... The double Rayleigh backscatter (DRB) effect in long distance CATV systems using fiber Raman amplifiers (FRAs) is investigated theoretically in the paper. As a comparison, performance of a system with erbium doped fiber amplifier (EDFA) is also evaluated. According to the simulation results, it is found that, in case of FRA, the increase of carrier-to-noise ratio (CNR) due to the DRB effect will not impair the performance more than that using EDFA. 展开更多
关键词 fiber Raman amplifier (FRA) double Rayleigh backscatter (DRB) carrier-to-noise ratio (CNR)
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Fiber core mode leakage induced by refractive index variation in high-power fiber laser 被引量:1
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作者 闫平 王雪娇 +5 位作者 黄昱升 付晨 孙骏逸 肖起榕 李丹 巩马理 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第3期336-343,共8页
This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the... This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results. 展开更多
关键词 double-clad fiber laser and amplifier Core loss cladding mode mode coupling theory
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Tensile Properties of 3-Dimension-4-directional Braided C_f/Si C Composite based on Double-scale Model 被引量:1
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作者 牛序铭 SUN Zhigang +1 位作者 宋迎东 GAO Xiguang 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2017年第6期1271-1279,共9页
The longitude tensile properties of 3-Dimension-4-directional(3D-4d) braided C/Si C composites(CMCs) were investigated with the help of a double scale model. This model involves micro-scale and unit-cell scale. In... The longitude tensile properties of 3-Dimension-4-directional(3D-4d) braided C/Si C composites(CMCs) were investigated with the help of a double scale model. This model involves micro-scale and unit-cell scale. In micro-scale, the tensile properties of fiber tows which involves matrix cracking, interfacial debonding, and fiber failure are studied. The unit-cell scale model can reflect the braided structure and simulate the tensile properties of 3D-4d CMCs by introducing the tensile properties of fiber tows into it. Quasi-static tensile tests of 3D-4d braided CMCs were performed on a PWS-100 test system. The predicted tensile stressstrain curve by the double scale model is in good agreement with that of the experimental results. 展开更多
关键词 3D-4d braided C/SiC composites double-scale model stress-strain curve fiber tows
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Occurrence of Features of Fiber Bragg Grating Spectra Having a Wavelength Corresponding to the Phase Mask Periodicity
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作者 Sui P. Yam Zourab Brodzeli +2 位作者 Scott A. Wade Greg W. Baxter Stephen F. Collins 《Journal of Electronic Science and Technology of China》 2008年第4期458-461,共4页
The use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, twice the Bragg wavelength, ... The use of a phase mask with 536 nm uniform pitch allowed the fabrication of a fiber Bragg grating for use at a Bragg wavelength of 785 nm. Reflection and transmission features at 1552 nm, twice the Bragg wavelength, associated with the phase mask periodicity were observed. However, when phase mask orders other than +1 were absent during fabrication the features at 1552 nm were not evident. 展开更多
关键词 double of the Bragg wavelength fiber Bragg grating phase mask Talbot interferometer.
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