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Open access

Zhongjian Li, Fei Yu, Ning Zhang, Yichen Lu, Ruru Pan and Weidong Gao

Abstract

In this article, a computerized method is proposed for simulating digital woven fabric (DWF) based on sequential yarn images captured from a moving yarn. A mathematical model of woven fabric structure is established by assuming that the crimped shape of yarns in weave structure is elastica, and the cross-sections of yarn in sequence image and fabric are circular and ellipse, respectively. The sequential yarn images, which are preprocessed and stitched first by image processing methods, are resized based on the mathematical model. Then a light intensity curve, which consists of radial curve model and axial curve model, is used to simulate the gray texture distribution of interlacing points in radial and axial directions. Finally, a Boole Matrix model is used to control the woven pattern. In the experiment, a slub yarn and a normal yarn samples with same count are applied to simulate gray texture fabrics. Then the gray fabrics are transformed to color fabrics based on three color maps. The fabric simulations are confined to single fabrics of plain, 2/2 matt, and 1/3 twill weaves.

Open access

Weikai He, Jianxiong Feng, Li Gao, Zhiwei Zhang and Hongwang Lu

Abstract

The Aselliscus Stoliczkanus bat, studied here, has intricately shaped structures surrounding the nostrils. These structures are hypothesised to have influence on animals’ acoustic radiation patterns. Using micro-tomography scanning technique, a 3D digital model of the noseleaf is reconstructed and biosonar beam pattern is analysed using a finite element method based on the 3D noseleaf model. The present research focuses on the conspicuous furrows in noseleaf, and our analysis allows to conclude the followings: a) structural details in noseleaf of Aselliscus Stoliczkanus bat can produce acoustic effects even if it is not adjacent to the nostrils, b) the furrows possess frequency-selective characteristics, c) the furrows have the function to manipulate the direction and width of the outgoing ultrasound wave.

Open access

Bo Zhu, Zhongjian Li, Xinwei Cao, Jianli Liu and Weidong Gao

Abstract

Unlike the normal sizing method, the foam sizing had been proven to be a low-add-on technology. To investigate the effect of foam sizing, film thickness, sized-yarn evenness, and size penetration rate were necessary to evaluate the performances of foam-sized yarns. However, the conventional image analysis of sized-yarn cross sections primarily relied on artificial testing with a low efficiency. This paper proposed a novel dynamic method to measure the sized-yarn properties including film thickness, sized-yarn evenness, and size penetration rate based on yarn sequence images captured from a moving yarn. A method of dynamic threshold module was adopted to obtain threshold for segmenting yarns in the sequence images. K-means clustering algorithm was applied to segment pixels of the images into yarn and background. To further remove burrs and noise in the images, two judgment templates were carried out to extract the information of yarn core. The film thickness, sized-yarn evenness, and size penetration rate were measured based on the yarn core of each frame in sequence images. In order to compare with the experimental results of the dynamic method, the yarn properties of the same samples were tested by static and artificial testing. Results revealed that the proposed method could efficiently and accurately detect the film thickness, sized-yarn evenness, and size penetration rate.

Open access

Dawei Gao, Zhenqian Lu, Chunxia Wang, Weiwei Li and Pengyu Dong

Abstract

Highly ordered TiO2 nanotube (TiO2 NT) arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT) arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT) arrays were obtained by successive ionic layer adsorption and reaction (SILAR) technique. The samples were characterized by the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) emission spectra, ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS). The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO) under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

Open access

Xiaoying Li, Gaoming Jiang, Xiaolin Nie, Pibo Ma and Zhe Gao

Abstract

This paper introduces a knitting technique for making innovative curved three-dimensional (3D) spacer fabrics by the computer flat-knitting machine. During manufacturing, a number of reinforcement yarns made of aramid fibres are inserted into 3D spacer fabrics along the weft direction to enhance the fabric tensile properties. Curved, flat-knitted 3D spacer fabrics with different angles (in the warp direction) were also developed. Tensile tests were carried out in the weft and warp directions for the two spacer fabrics (with and without reinforcement yarns), and their stress–strain curves were compared. The results showed that the reinforcement yarns can reduce the fabric deformation and improve tensile stress and dimensional stability of 3D spacer fabrics. This research can help the further study of 3D spacer fabric when applied to composites.

Open access

Zengke Li, Yifei Yao, Jian Wang and Jingxiang Gao

Abstract

A robust Kalman filter improved with IGG (Institute of Geodesy and Geophysics) scheme is proposed and used to resist the harmful effect of gross error from GPS observation in PPP/INS (precise point positioning/inertial navigation system) tightly coupled positioning. A new robust filter factor is constructed as a three-section function to increase the computational efficiency based on the IGG principle. The results of simulation analysis show that the robust Kalman filter with IGG scheme is able to reduce the filter iteration number and increase efficiency. The effectiveness of new robust filter is demonstrated by a real experiment. The results support our conclusion that the improved robust Kalman filter with IGG scheme used in PPP/INS tightly coupled positioning is able to remove the ill effect of gross error in GPS pseudorange observation. It clearly illustrates that the improved robust Kalman filter is very effective, and all simulated gross errors added to GPS pseudorange observation are successfully detected and modified.