Advanced Materials Research Vols. 301-303

Abstract: We present a novel single-polarization single-mode photonic crystal fiber (SPSM-PCF) design with four lines of small elliptical air-holes in order to obtain wider bandwidth for SPSM operation. The characteristics of the proposed SPSM-PCF are studied by using a full-vector finite element method (FEM) with perfect matched layer (PML) boundary conditions. At the wavelength of 1.55 µm, the confinement loss of the x-polarized mode is lower than 0.5 dB/km, whereas the loss of the y-polarized mode is larger than 50 dB/km. Compared with the case of x-polarized mode, the y-polarized mode can be suppressed in the PCF. Then, the SPSM operation is obtained. The proposed PCF can perform SPSM operation with broadband of 600 nm for considering the confinement loss ratio and the loss difference.

Abstract: PVA/ zinc acetate sol–gel were fabricated into thin PVA/ zinc acetate composited fibers films by using electrospinning technique. After annealing of the above precursor fibers, ZnO:Al nanofibers with a diameter of 100-700 nm and high length-diameter ratio were obtained successfully. The ZnO:Al nanofibers were characterized by XRD, SEM, and PL, respectively. The XRD results show that Al-doped ZnO nanofibers present ZnO hexagonal structure. PL spectra display that the ZnO: Al nano-fibers have a strong UV emission properties.

Abstract: This paper compares capacitive and photoelectric method for measuring yarn evenness, and presents a new yarn unevenness on-line measurement system to detecting accurately yarn appearance diameter. By means of researching coefficient of diameter variation and mass variation, the relation model of variation coefficient is established, and the experimental data shows excellent correlation between coefficient of diameter variation and coefficient of mass variation and approximate linear relationship. The laser on-line measurement system of yarn evenness can accurately measure yarn diameter and calculate the coefficient of variation, which is suitable for the production field measurement.

Abstract: Hemodialysis is the main treatment of acute and chronic renal failure, and the selection of hemodialysis membrane materials is the key factor that determines the curative possibilities. By changing the membrane forming conditions, we have spun polyvinylidene fluoride (PVDF) hollow fiber membranes with the same inner diameters but different wall thicknesses. Via centrifugal moulding, we have also made membranes into dialyzers to study the mechanical performance of the membranes and the dialysis performance of the dialyzers. The results show that the mechanical performance meets the demand of dialysis. For the dialyzers with 30μm fiber walls, the clearance rates of urea and lysozyme are 90% and 75% respectively, and the rejection rate of bovine serum albumin (BSA) comes to 90% plus. The increase of the mass content of the dope solution polyethylene glycol (PEG) from 19% to 22% decreases the rejection rate of BSA.

Abstract: Random forest has demonstrated excellent performance to deal with many problems of computer vision, such as image classification and keypoint recognition. This paper proposes an approach to classify materials, which combines random forest with MR8 filter bank. Firstly, we employ MR8 filter bank to filter the texture image. These filter responses are taken as texture feature. Secondly, Random forest grows on sub-window patches which are randomly extracted from these filter responses, then we use this trained forest to classify a given image (under unknown viewpoint and illumination) into texture classes. We carry out experiments on Columbia-Utrecht database. The experimental results show that our method successfully solves plain texture classification problem with high computational efficiency.

Abstract: Understanding of the prosperities of the carbon nanotubes (CNTs) probes is crucial when measuring surface using atomic force microscopy (AFM). In this paper, we investigate the deformation of CNTs by adding lateral forces based on molecular dynamics (MD) simulation. In the simulation, Tersoff many-body potential function is used to describe the interaction between atoms. The movement of CNTs is periodic vibration, which is different from traditional material. We analyzed the vibration of different CNTs including single-walled carbon nanotubes (SWCNTs) and sharpened CNTs. Similarities and differences between different CNTs during the deformation are illustrated. It is shown that sharpened CNTs have better stiffness without declining the resolution of AFM. By analyzing the results obtained from the MD simulation, it is found that the sharpened CNTs may be more suitable as AFM probes.

Abstract: Titanium alloys which exhibit excellent material properties like a high strength to weight ratio and good corrosion resistance have become the important structural materials in the applications of the aerospace. However, it’s quite difficult to repair the damages of the titanium alloy parts such as fatigue crack and erosion resulted from poor working environment using the traditional manufacturing technology while the problem can be easily solved with the help of laser cladding technology. For the excellent quality of the fixed parts, it is extraordinarily significant to obtain the rule of the temperature and thermal stress distribution in the cladding process. To investigate the influencing rule of cladding coating's temperature and stress on laser cladding process parameters, the model of laser cladding based on TC4 titanium alloy is built by the way of finite element method (FEM). This model encompasses the effects of the temperature-dependent thermal conduction and radiation as well as the latent heat of fusion. Different laser processing parameters are chosen to calculate the temperature and stress of cladding layer.The result shows that the temperature of the clad coating is positive correlation with the raise of laser power and the depth of the powder layer, and negative correlation with the raise of scanning speed and the laser spot diameter. In addition, the transient stress of clad coating is augmented with the increase of laser scanning velocity, laser spot diameter and the depth of the clad coating while it’s negative correlation with the raise of laser power. The numerical results provide the theoretical guidance for optimization of the laser cladding parameters on TC4 titanium alloy.

Abstract: The thermal conductivity of polyacryonitrile-based carbon fiber/pitch-based carbon/carbon composites was simulated by the finite element analysis. After the density, thermal capacity and thermal conductivity of graphite and carbon fiber were given for known parameters, the geometric grid figure) was generated after the Gambit software processed the unit geometric model grids and the thermal conductivities of carbon/carbon composites were simulated by the Fluent software.

Abstract: This paper pay attention to the Carbon Nanotubes Threads (CNTs) in the 3D Braided Composite Material . CNTs as a piezoelectricity sensor, can be braided in the 3D Braided Composite Material. The resistance of the sensor will be changed with the correspondent stress and strain on the 3D Braided Composite Material. The resistance of the Carbon Nanotubes Threads can be detected by computer. So, the stress and strain on the 3D Braided Composite Material can be obtained betimes.

Abstract: This study investigated the structures and properties of cationic dyeable poly(ethylene terephthalate) (CDP) and easy cationic dyeable poly(ethylene terephthalate) (ECDP) by FTIR, X-ray diffraction, mechanical test, and DSC. The results showed that the FTIR spectrums of CDP and ester-type ECDP fibers were similar to the that of PET. It suggested that the adding of the third monomer and the fourth monomer had good compatible with the original structure unit of PET. the position of X-ray diffraction peak of CDP and ester-type ECDP were the same as which of PET, the third monomer and the fourth monomer did not pack into the original polyester unit cell but concentrated at the polyester crystalline surface and the amorphous regions.With adding the third monmome and the fourth monmomer, the initial modulus of the CDP and ester-type ECDP fibers became inferior. But the breaking elongation of them increased. The DSC suggested that The melting range of CDP and ECDP finished fiber were wider than that of PET fiber, but the melting point and crystallinity were less than them of PET fiber.