652 publications from this institution
This paper addresses the problem of detecting points on or near the boundary of a dataset sampled, potentially with noise, from a compact manifold with boundary. We extend recent advances in doubly stochastic scaling of the Gaussian heat kernel via Sinkhorn iterations to this setting. Our main contributions are: (a) deriving a characterization of the scaling factors for manifolds with boundary, (b) developing a boundary direction estimator, aimed at identifying boundary points, based on doubly stochastic kernel and local principal component analysis, and (c) demonstrating through simulations that the resulting estimates of the boundary points outperform the standard Gaussian kernel-based approach, particularly under noisy conditions.
No abstract is provided for this article.
Mechanical property is one of the most important properties of nanofiber membranes. Electrospinning is widely used in the preparation of nanofibers due to its advantages such as good stability and easy operation. Compared with some nature silk, the mechanical properties of nanofibers prepared by electrospinning are poor. Based on the principle of vortex spinning and DNA structure, this paper designed an air vortex electrospinning device that can control the structure of macromolecular chains in nanofibers. When a weak air vortex is generated in the electrospinning process, the macromolecule chains will entangle with each other and form a DNA-like structure so as to improve the mechanical property. In addition, when a strong air vortex is generated during the electrospinning process, the nanofibers will adhere to each other, thereby enhancing the mechanical property and enlarging the pore size.
Copper-1,3,5-benzoic acid (Cu-BTC) was synthesized by the hydrothermal method, which had regular octahedral morphology. The Cu-BTC particles were used as additives in the polyacrylonitrile (PAN) solution fabricate Cu-BTC/PAN membrane by the electrostatic spinning method, its good filtration performance was witnessed experimentally.
No abstract is provided for this article.
Zirconia nanocomposite nanofibres were prepared from several different as-spun fibre polymers fabricated by the bubble spinning, a novel spinning method for mass production of nanofibres. To obtain various zirconia nanocomposites, several polymers were used as zirconia powder carriers for a bubble spinning. The morphology, the thermal/mechanical property and pore-size distribution of the obtained nanofibres were characterised and the theoretical fluid mechanics analyses were described, then a comparative and verified study drew a conclusion on the distinctions of their principle structural diagrams, resulting in different properties. Among all these nanocomposites, PAN-based zirconia nanocomposite was found to outperform all the rest nanocomposites, which had the best thermal stability, the most uniform pore structure and the highest strength.
In this Letter, we propose to use the Cantor-type cylindrical-coordinate method in order to investigate a family of local fractional differential operators on Cantor sets. Some testing examples are given to illustrate the capability of the proposed method for the heat-conduction equation on a Cantor set and the damped wave equation in fractal strings. It is seen to be a powerful tool to convert differential equations on Cantor sets from Cantorian-coordinate systems to Cantor-type cylindrical-coordinate systems.
This paper aims to present the significance of the Hall current and Joule heating impacts on a peristaltic flow of a Rabinowitsch fluid through tapered tube. The Darcy–Forchheimer scheme is used for a porous medium; a mild stenosis is considered to study the impacts of radiative heat transfer and chemical reactions. Convective conditions are postulated for heat and mass transfer. In the meantime, the slip conditions are presumed for the velocity distribution. Soret and Dufour features bring the coupled differential systems. The hypotheses of a long wavelength and low Reynolds number are employed to approximate the governing equations of motion, and finally the homotopy perturbation method is adopted for numerical study. Pumping characteristics are revealed and the trapping procedure correlated with peristaltic transport is elucidated. The present study is very important in many medical applications, such as the gastric juice motion in the small intestine and the flow of blood in arteries. The mechanism of peristaltic transport with mild stenosis has been exploited for industrial applications like sanitary fluid transport and blood pumps in heart-lung machine. The influences of various physical parameters of the problem are debated and graphically drawn across a set of figures. It is noted that the axial velocity is reduced with the increase of the Hartmann number. However, enhancing both the Rabinowitsch parameter and the Forchheimer parameter gives rise to the fluid velocity. As well, it is debated that Rabinowitsch fluid produces a cubic term of pressure gradient. Therefore, the relation between mean flow rate and the pressure rise does not stay linear. It is recognized that the temperature rises with the enhancement of both Dufour number and Soret number. Furthermore, it is illustrated that the concentration impedes with the increase of the mass transfer Biot number. Also, it is revealed that the trapped bolus contracts in size by enlarging the maximum height of stenosis.
In the present paper an asymptotic gas magnetohydrodynamic system is formulated in variational principles for the first time via the semi-inverse method proposed by He. Thus, a new theoretical basis for the finite element method is founded and a new versatile way to deal with discontinuity (shock) is suggested.
No abstract is provided for this article.
Wool fiber has a complex hierarchic structure. The multi-scale fibrils are assembled to form a tree-like channel net in wool fiber, providing an efficient heat transfer property. The optimal inner configuration of wool fiber can also be invited to biomimic design of textile fabrics to improve the thermal comfort of cloth. A heat transfer model of biomimic multi-scale fabric using the fractal derivative is established. Theoretical analysis indicates that the heat flux efficiency in the biomimic fabric can be 2 orders of magnitude comparing with that of the continuous medium.
