Stress and modal birefringence of single-mode specialty optical fibers with three-stress regions

Stress-induced birefringence and modal birefringence of single-mode specialty optical fibers with three stress regions are numerically analyzed by the vector finite element method. Stress distribution and stress-induced birefringence distribution of three kinds of optical fibers with different cross structures are presented and compared, and the influence on the stress-induced birefringence by temperature change are analyzed as well. The results show that the fibers with three-stress regions have a lower linear birefringence, which is very important for the fabrication of the circular polarization-maintaining fiber with high performance drawn from the same fiber preform by using the spinning method.

The stress-microstructure relationship in an evolving mixing layer of fiber suspensions

The equations for fiber suspensions in an evolving mixing layer were solved by the spectral method, and the trajectory and orientation of fibers were calculated based on the slender body theory. The calculated spatial and orientation distributions of fibers are consistent with the experimental ones that were performed in this paper. The relationship between the microstructure of fibers and additional stress was examined. The results show that the spatial and orientation distributions of fibers are heterogeneous because of the influence of coherent vortices in the flow, which leads to the heterogeneity of the additional stress. The degree of heterogeneity increases with the increasing of St number and fiber aspect ratio. The fibers in the flow make the momentum loss thickness of the mixing layer thicker and accelerate the vorticity dispersion.

Resistance Responses of Carbon Fiber Cement to Cycled Compressive Stresses

The stress-resistance relationship of carbon fiber cement was studied. Attention has been paid to explore the improvement of the stress-resistance sensitivity under cycled stress restriction. The prismy carbon fiber cement sensors were pre-fabricated. The factors such as contents of carbon fibers, silica fume, dispersant and the w/c were taken into account. The electrical resistance variations with the dynamic and static loads were simulated using a strain-controlled test machine. The test results show that there is an optimal fiber content, with which the compression-sensitivity achieves a high level. The addition of silica fume can improve the sensitivity. Under the optimal test conditions, the measured resistances can greatly correspond with the changes of the load.

Interfacial stress transfer behavior in a specially-shaped fiber/matrix pullout test

因为特殊设计的形状能帮助改进纤维和接口的结合的力量，特殊设计的纤维广泛地在设计实践被使用。在这篇论文学习了界面砍特殊设计的纤维的双方上的压力转移行为当它正在被拔出时；在哪个三维的光弹性的自动分析被采用，有限元素方法被采用。压力转移主要在这个区域发生在纤维鈥檚 附近的结果表演嵌入压力到达它的批评的点的结束，导致接口的 debonding。在 debonding 前，作为撤退，装载增加，山峰价值砍应力从嵌入的结束沿着纤维转到矩阵的内部，然后因为它的妨碍，在纤维的钩的部分停止。当接口作为负担增加开始到 debond 时， shear 压力能被转移到钩的部分。关键词增强纤维的 composites - 特殊塑造的纤维 - 界面的压力转移 - 光弹性 - 女性工程被中国(10662005 ) 的国家自然科学基础支持。

Stress Sensing by an Optical Fiber Sensor: Method and Process for the Characterization of the Sensor Response Depending on Several Designs

In this paper we propose an analyzing of the response of a stress optical fiber sensor of which we proposed several design. We show that an optical fiber sensor with these designs can covenanting allow the measuring the force/stress applied to a mechanical structure or which it is linked, by optimizing the uses of appropriate materials for constituting the sensor support. The experiment that we introduce to validate our approach based in principles includes design with a support bearing a multimode optical fiber organized in such a way that the transmitted light is attenuated when the fiber-bending angle coming from stitching in holes of the support is modified by the effects of the force/stress applied to the optical fiber sensor realized in this way. The tests realized concern the most relevant parameters that define the performances of the stress sensor that we propose. We present the problems that we to solved for the optimization of the sensor for selecting the more efficient material for the optical fiber sensor support related to a relevant choice of optical fibers.

Characterization of the 19 Novel Cotton FLA Genes and Their Expression Profiling in Fiber Development and in Response to Phytohormones and Salt Stress

Fasciclin-like arabinogalactan proteins(FLAs),a subclass of arabinogalactan proteins(AGPs),are usually involved in cell development in plants.To investigate the expression profiling as well

Some Further Considerations about the Theory of Elastic Stress Transfer from Partially Embedded Axially Loaded Fiber to Matrix

In this paper the elastic stress transfer from the fiber to the matrix is analysed for fiber-reinforcedcomposites when the fiber is loaded axially.The dependence of the elastic stress transfer on the as-pect ratio of the fiber,the volume fraction of the fiber,the fiber-to-matrix elastic modulus ratio andthe Poisson’s ratio of the fiber and the matrix has been shown in detail.

Effects of Fiber Supplementation for Four Weeks on Athletic Performance in Japanese College Athletes: A Case Study—Measurement of the Athletic Performance, Salivary Biomarkers of Stress, and Mood, Affect Balance

Aim: In this study, we explored the effects of dietary fiber on athletic performance. Methods: Twenty healthy college athletes (male/female, 1/1) consumed 6 grams of dietary fiber (Fiberpro, Taiyo Lab Inc., Tokyo) daily for four weeks and were evaluated for their athletic performance, salivary biomarkers of stress (α-amylase activity pre-post exercise, cortisol, melatonin, and secretory immunoglobulin A (SIgA) levels), and mood/affect using the Profile of Mood State 2nd edition (POMS 2®). Measurements were taken at baseline (before supplementation), at Week 4 (after 4 weeks of supplementation), and at Week 8 (4 weeks after the completion of supplementation). Results: Results showed that athletic performance and exercise-induced elevation in salivary α-amylase activity improved with Fiberpro supplementation in both men and women. Further, the Anger-Hostility scale in POMS was significantly elevated in men;in women, an increase in Vigor-Activity score, a single index of positive mood, was noted. These findings suggest that Fiberpro may induce differential affective responses in men and women. Meanwhile, Fiberpro did not affect the normal diurnal changes in salivary melatonin and SIgA levels, but it appeared to augment the normal circadian patterns of cortisol, an effect that persisted for a month without Fiberpro intake. We propose that boosting fiber intake in young, healthy athletes may improve gut microbiota and confer resilience against stress.

Effect of fiber distribution on residual thermal stress in titanium matrix composite

Residual thermal stresses (RTS) of SCS-6 SiC/Ti-24Al-11Nb composite were analyzed by using finite element method (FEM). Three models of fiber array in the composite and the effect of fiber distance on the RTS were discussed. In all the three models compressive stress was found in the radial direction and tensile stress in the tangential direction. It is pointed out that, in real composite system, hexagonal fiber geometry is superior because the distribution and the magnitude of the residual stress are similar to those in single fiber model. In square fiber geometry, it is easier to make the matrix crack due to the larger residual tangential stress. RTS becomes very large and changes violently when the fiber distance is less than 15 μm or so, therefore too high fiber volume is apt to result in matrix crack.

Fatigue tests of composite beam by steel fiber reinforced self-stressing concrete in the hogging bending

Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete (SFRSC) as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar's stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.

Effects of Matrix Features on Stress Transfer of Short Fiber Composites

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Polymyxin B Alleviates Angiotensin II-Induced Stress Fiber Formation and Cellular Hypertrophy

Polymyxin B is widely used antibiotic in the clinic for resistant Gram-negative infections. In addition, polymyxin B-immobilized hemoperfusion cartridge has been used for endotoxin removal therapy in patients with septic shock. The aim of this study was to investigate the anti-fibrotic and anti-cellular hypertrophic effects of polymyxin B, and further to explore its possible mechanism. Polymyxin B (3, 10 μM) significantly inhibited stress fiber formation induced by angiotensin II (Ang II) in rat heart-derived H9c2 cells. Furthermore, polymyxin B (1 - 10 μM) showed a potent inhibitory effect on Ang II-induced cellular hypertrophy in H9c2 cells. Under the mechanism study, the inhibitory activities of polymyxin B against kinases involved in cellular hypertrophy such as AKT1, CAMK, GRK5, GSK3β, MLCK, PKC, PKD2, AMPK, ROCK2, p70S6K, SGK1were evaluated. Polymyxin B possesses a potent G protein related kinase 5 (GKR5) inhibitory activity with IC50 value of 1.1 μM, and has an ATP non-competitive inhibitory mode. Taken together, these results indicate that polymyxin B alleviates Ang II-induced stress fiber formation and cellular hypertrophy, and propose that one mechanism underlying these effects involves inhibition of the GRK5 pathway.

Landslide Monitoring Based on High-Resolution Distributed Fiber Optic Stress Sensor

A landslide monitoring application is presented by using a high-resolution distributed fiber optic stress sensor. The sensor is used to monitor the intra-stress distribution and variations in landslide bodies, and can be used for the early warning of the occurrence of the landslides. The principle of distributed fiber optic stress sensing and the intra-stress monitoring method for landslides are described in detail. By measuring the distributed polarization mode coupling in the polarization-maintaining fiber, the distributed fiber stress sensor with stress measuring range 0 to 15 MPa, spatial resolution 10 cm and measuring range 0.5 km, is designed. The warning system is also investigated experimentally in the field trial.

Thermomechanical Stress in the Evolution of Shear of Fiber-Matrix Interface Composite Material

This work aims to describe the behavior of the interface using the method of load transfer between fiber and matrix in a composite material. Our contribution is to track the Evolution of the thermomechanical behavior by establishing a new mathematical model that describes the variation of shear stress along the interface. This model has been implemented in code in C++. The results revealed that the shear of the interface increases with temperature. This increase is partly due to the difference in expansion coefficient between fiber and matrix. The composite studied is T300/914;Carbon-Epoxy.

Susceptible time window and endurable duration of cotton fiber development to high temperature stress

The development of the cotton fiber is very sensitive to temperature variation, and high temperature stress often causes reduced fiber yield and fiber quality. Short-term high temperature stress often occurs during cotton production, but little is known about the specific timing and duration of stress that affects fiber development. To make this clear, pot experiments were carried in 2014 and 2015 in a climate chamber using cotton cultivars HY370WR(less sensitive variety) and Sumian 15(heat sensitive variety), which present different temperature sensitivities. Changes of the most important fiber quality indices(i.e., fiber length, fiber strength and marcironaire) and three very important fiber development components(i.e., cellulose, sucrose and callose) were analyzed to define the time window and critical duration to the high temperature stress at 34°C(max38°C/min30°C). When developing bolls were subjected to 5 days of high temperature stress at different days post-anthesis(DPA), the changes(Δ%) of fiber length, strength and micronire, as a function of imposed time followed square polynomial eq. as y=a+bx+cx^2, and the time around 15 DPA was the most sensitive period for fiber quality development in response to heat stress. When 15 DPA bolls were heat-stressed for different durations(2, 3, 4, 5, 6, 7 days), the changes(Δ%) of fiber length, strength and micronire, as a function of stress duration followed logistic equations y=A_1-A_2/1+(x/x_0)~p+A_2. Referred to that 5, 10 and 15% are usually used as criteria to decide whether techniques are effective or changes are significant in crop culture practice and reguard to the fiber quality indices change range, we suggested that 5% changes of the major fiber quality indices(fiber length, fiber strength and micronaire) and 10% changes of fiber development components(cellulose, sucrose and callose) could be taken as criteria to judge whether fiber development and fiber quality have been significantly affected by high temperature stress. The key time window for cotton fiber development in response to the high temperature stress was 13–19 DPA, and the critical duration was about 5 days.

3D-SiO_(2)-fiber中间层对SiC与Nb真空钎焊的影响

缓解异种材料钎焊接头残余应力过程中,针对颗粒增强相添加量少、团聚等问题,引入一种新型三维SiO_(2)短纤维编织,呈疏松、多孔结构的复合材料中间层(3D-SiO_(2)-fiber)辅助SiC陶瓷与Nb钎焊连接.采用SEM,XRD和电子万能试验机等对活性钎料在3D-SiO_(2)-fiber中间层表面润湿性、接头微观组织和力学性能进行表征与分析.结果表明,当Ti元素含量从4.5%增加到6.0%,AgCu-Ti活性钎料在3D-SiO_(2)-fiber中间层表面润湿角从90°降低到3°,润湿性得到显著改善,且AgCu-Ti活性钎料浸入3D-SiO_(2)-fiber中间层深度不断增加;随着钎焊温度的提高(950~980℃)及保温时间(10~25 min)的延长,SiO_(2)短纤维与AgCu-6.0Ti活性钎料反应逐渐充分.该方法不仅保证SiO_(2)短纤维能够大量添加到合金钎料中,而且形成Cu_(3)Si,TiSi,α-Ti及Ti_(2)Cu颗粒相弥散分布于焊缝中,从而有效缓解钎焊接头残余应力,提高接头力学性能,实现陶瓷与金属复合构件的可靠连接.

Fiber Bragg grating monitors for thermal and stress of the composite insulators in transmission lines

Running composite insulators are prone to failure due to their harsh surrounding work environment, which directly affects the safe operation of transmission lines. This paper puts forward the method of using fiber Bragg grating(FBG) as the monitors to parameters correlated with thermal and stress of the composite insulators in transmission lines at working status. Firstly, monitoring points are found out by the mechanical test on composite insulator samples. Secondly, based on the monitoring theory, this paper introduces the feasibility design frame of the composite insulator with FBG implanted in the rod and the online monitor system. At last, it describes applications of this monitor system in the field of transmission lines.

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical

光纤光栅温度应力传感教学实验装置

针对目前市场上可直接用于光纤光栅传感实验教学的装置较少,前沿科研技术和本科实验教学相脱节现状,设计了基于光纤光栅的温度应力传感教学装置。该装置包括光纤激光器、光谱仪和上位机控制软件3部分。光纤激光器实现了1 550 nm左右的激光输出,利用光谱仪测量光纤光栅中心波长的改变,并采集数据输入计算机,上位机控制软件用于图形显示和数据存储等。该实验装置操作简单、组装灵活、重复性和稳定性好,可用于本科实验教学。将前沿科学技术引入本科实验教学,促进了科学研究与本科实验教学相融合,实现了科研教学水平的同步提高。

Charactersitics of Stress-strain Curve of High Strength Steel Fiber Reinforced Concrete under Uniaxial Tension

A whole of 110 specimens divided into 22 groups were tested with varying the volume fraction of steel fibers and the matrix strength of these specimens. The stress-strain behaviors of four types of steel fiber reinforced concrete (SFRC) under uniaxial tension were studied experimentally. When the matrix strength and the fiber content increase, the tensile stress and tensile strain vary differently according to the fiber type. The mechanisms of reinforcing effect for different types of fiber were analyzed and the stress-strain curves of the specimens were plotted. Some experimental factors for stress or strain of SFRC were given. A tensile toughness modulus Re_ 0.5 was introduced to evaluate the toughness characters of SFRC under uniaxial tension. Moreover, the formula of the tensile stress-strain curve of SFRC was regressed. The theoretical curve and the experimental ones fit well, which can be used for references in construction.