Propagation of solitary waves in inhomogeneous erbium-doped fibers with third-order dispersion,self-steepening and gain/loss

We propose a generalized inhomogeneous Hirota–Maxwell–Bloch system which explains ultrashort optical pulse propagation in an inhomogeneous nonlinear, dispersive fiber doped with two-level resonant atoms. For this system, higher order effects like third-order dispersion and self-steepening are considered, which are assumed to be inhomogeneous together with group velocity dispersion and self-phase modulation. We have obtained a general solitary wave solution by using Lax pair and Bäcklund transformation techniques. We have analyzed various solitary wave forms like snaking solitons, classic solitons and compressed pulses by controlling the physical parameters and inhomogeneous functions.     

Color separation for colored fiber blends based on the fuzzy C‐means cluster

Colored fibers can be blended in a certain proportion to achieve a specific color. It is a very hard task for the colorist to find a good recipe to meet the final product without the aid of computer. In this article, a color separation method for the colored fiber blends is discussed to substitute for some manual work. The fuzzy C‐means cluster is a way to group the color in the colored fiber blends image. The distance index, which is a key factor during the fuzzy C‐means cluster process, is calculated in the RGB color space and the HSV color space with some transformation. The final experiment result proved that the colors of each pixel in the blends' image can be replaced by corresponding cluster center associating colors in the HSV color space, and the main texture as well as the main color information about the fibers in the image is preserved. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012     

3D-SWiM: 3D vision based seam width measurement for industrial composite fiber layup in-situ inspection

Industrial composite fiber has been widely used in the high-end manufacturing because of its superior stiffness and strength. To ensure the quality of composite fiber placement in making high-end and lightweight aerospace products, it needs reliable composite fiber layup in-situ inspection. An accurate seam width measurement is an indispensable procedure during the layup inspection. However, the traditional seam measurements may fail in presence of surface curvature variance, curved edges between sheets, to name a few. This paper intentionally designs a novel 3D vision based Seam Width Measurement for Industrial Composite Fiber Layup In-situ Inspection (called 3D-SWiM). It aims to address three major challenges in measuring the seam width between the composite fiber sheets, namely, seam region over-segmentation, failures on region of interests (ROI) seam detection, seam width measurement inconsistency. Firstly, the region growing with semantic refinement is designed for 3D point cloud clustering, to overcome over-segmentation on seam regions. Afterwards, the gridding model with edge discrimination is applied to extract the 3D potential candidates in the edge areas. Eventually, we use the cubic B-spline fitting model to describe the seam region curves and the improved particle swarm optimization model to estimate the minimum and maximum distance between the seam edges. 3D-SWiM has been evaluated extensively on the developed composite fiber layup platform. The comparisons with the state-of-the-art methods (such as HT and GFM) on the region-of-interest segmentation, seam extraction and seam width measurement have been performed and the experimental results prove the competitive performance in composite fiber layup in-situ inspections.     

Wavelength switchable L-band erbium-doped fiber laser employing C-band EDFA as gain medium

A new structure for the L-band multiwavelength switchable erbium-doped fiber laser is proposed. Overlapping laser cavities are formed by cascading fiber Bragg gratings as reflectors in a ring structure with a C-band EDFA as a common gain medium. The proposed laser is made to be wavelength-switchable by individually adjusting the loss of each overlapping cavity. Instead of using an L-band EDFA as the gain medium in the L-band fiber laser, we have experimentally demonstrated that by tailoring the gain of the C-band EDFA to have a significant gain tilt in the L-band, a lasing power efficiency of 26% can be achieved over a wide range of switchable lasing wavelengths. Following this optimal design, the side-mode suppression ratio and the minimal separation between two switchable lasing wavelengths were found to be over 42 dB and 0.33 nm, respectively.     

The Effect of Size and Shape of Austenite Grains on the Mechanical Properties of a Low‐Alloyed TRIP Steel

The effects of size and shape of austenite grains on the extraordinary hardening of steels with transformation induced plasticity (TRIP) have been studied. The deformation and transformation of austenite was followed by interrupted ex situ bending tests using electron backscatter diffraction (EBSD) in a scanning electron microscope (SEM). A finite element model (FEM) was used to relate the EBSD based results obtained in the bending experiments to the hardening behavior obtained from tensile experiments. The results are interpreted using a simple rule of mixture for stress partitioning and a short fiber reinforced composite model. It is found that both, the martensite transformation rate and the flow stress difference between austenite and martensite significantly influence the hardening rate. At the initial stage of deformation mainly larger grains deform, however, they do not reach the same strain level as the smaller grains because they transform into martensite at an early stage of deformation. A composite model was used to investigate the effect of grain shape on load partitioning. The results of the composite model show that higher stresses develop in more elongated grains. These grains tend to transform earlier as it is confirmed by the EBSD observations.     

Obtaining sugars from coconut husk,defatted grape seed,and pressed palm fiber by hydrolysis with subcritical water

In this work, three residues from the food industry (coconut husk, defatted grape seed and pressed palm fiber) were subjected to subcritical water hydrolysis with the aim of producing fermentable sugars. Hydrolysis kinetics were determined using a semi-batch unit equipped with a 50 mL reactor. The process was conducted at 208 °C and 257 °C for 30 min, with water flow rate of 33 mL/min and under 20 MPa. The liquefaction degree of the raw materials increased with temperature. The total reducing sugars recovered also increased with temperature. Maximum total reducing sugars recovered for coconut husk, defatted grape seed and pressed palm fiber using SWH were 11.7%, 6.4% and 11.9% from total raw material, respectively. Coconut husk presented the highest amount of monosaccharides (3.4%), followed by pressed palm fiber (2.4%) and defatted grape seeds (0.7%). On the other hand, the degradation products that are also fermentation inhibitors increased with temperature as well. Each raw material presented a different monosaccharides and inhibitors profile, which indicates that SWH should be evaluated and optimized individually for each case.     

Enhanced microwave-absorbing properties of FeCo magnetic film-functionalized silicon carbide fibers fabricated by a radio frequency magnetron method

Silicon carbide (SiC) fibers have potential application in microwave absorption materials in recent years. In this study, we provide a new method for improving the microwave-absorbing properties of SiC fibers. Magnetic FeCo films were fabricated on SiC fibers at low temperature and high vacuum by a radio frequency magnetron sputtering method. The properties of FeCo film/SiC fiber (FeCo/SiC_f) composites were investigated. When compared with SiC fiber, the FeCo/SiC_f composites exhibit excellent microwave-absorbing properties in the microwave range, with enhancements in the optimal reflectivity loss from −5.03 to −25.51 dB. This excellent performance may be because of the magnetic loss due to ferromagnetic resonance and interfacial polarization, thus inducing dielectric relaxation. In addition, the magnetic properties of FeCo/SiC_f composites are significantly improved: the value of saturation magnetization reaches up to 41.45 emu/g and the coercivity is 116.27 Oe. In addition, the strength of SiC fiber remains at 99.17% after the fabrication process. The method provided in this study for enhancing the microwave-absorbing properties of FeCo/SiC_f composites will pave a new way for the development of SiC microwave-absorbing materials.     

基于PLC的缠绕机低成本控制系统设计与应用

本文利用可编程控制器的多轴插补、高速定位功能,将继电-接触器控制的普通缠绕机,改造成为PLC控制的数控缠绕机,采用玻璃纤维预浸胶带分别进行纵、环向缠绕成型,并对纵向外移量、环向缠绕长度、排纱精度、缠绕张力及表面温度等参数进行测量与分析,并对利用该缠绕机缠绕成型的6台150容器进行水压爆破实验,得到水压爆破压强均略高于设计值,且离散较小,表明:利用PLC控制的缠绕机能够满足工艺要求,可以进行纤维缠绕制品的稳定生产。改造后的PLC控制数控缠绕机具有缠绕精度高、产品性能稳定、成本低、操作界面友好、设备运行稳定及可维护性好等优点,本文方法适合于机械式缠绕机的技术升级。     

高山无线发射台防雷经验与思考

摘要：论述了高山发射台在防雷方面采取的综合防雷技术措施，光缆在信号防雷方面的优点以及使用避雷针弊大于利。