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Tianjin, China

Tianjin Polytechnic University is a university in Tianjin, China under the municipal government. It is also referred to as TJPU. The university was founded in 1912 and currently has fourteen colleges on two campuses in the city. The old campus is located in the Hedong District , and the new one is in the Xiqing District . Wikipedia.

Ni Y.-H.,Tianjin Polytechnic University | Li X.,Hong Kong Polytechnic University
Systems and Control Letters | Year: 2013

In this paper, the consensus problems of the continuous-time integrator systems under noisy measurements are considered. The measurement noises, which appear when agents measure their neighbors' states, are modeled to be multiplicative. By multiplication of the noises, here, the noise intensities are proportional to the absolute value of the relative states of an agent and its neighbor. By using known distributed protocols for integrator agent systems, the closed-loop system is described in the vector form by a singular stochastic differential equation. For the fixed and switching network topology cases, constant consensus gains are properly selected, such that mean square consensus and strong consensus can be achieved. Especially, exponential mean square convergence of agents' states to the common value is derived for the fixed topology case. In addition, asymptotic unbiased mean square average consensus and asymptotic unbiased strong average consensus are also studied. Simulations shed light on the effectiveness of the proposed theoretical results. © 2013 Elsevier B.V. All rights reserved. Source

A composite catalytic membrane applied to catalytic esterification and preparation method thereof are provided. The composite catalytic membrane is porous, and includes nonwoven fabric as base membrane and catalytic coating which is formed on the surface of nonwoven fabric and in the pores and gaps between the nonwoven fabric fibers. The catalytic coating uses solid acid as catalyst and polymer or modified sulfonated polymer as membrane-forming material. The membrane is formed by coating or immersion method, and the composite catalytic membrane is obtained by cross-linking after forming. The greenization and high efficiency of catalytic esterification and preparation of biodiesel can be achieved owing to the microporous structure and huge specific surface area of the composite catalytic membrane. The composite catalytic membrane has high mechanical strength, good reproducibility and stability and easily enables continuous repetitive production of catalytic esterification. The process is simple and easy to control and scale-up.

A composition for preparation of a hollow fiber porous membrane including 40-60 wt. % a polymer matrix, 20-30 wt. % an organic mixed solution, and 20-40 wt. % a water-soluble substance. The polymer matrix is a polymer capable of dissolving in an organic solvent and melt processing. The organic mixed solution is a mixture comprising 60-90 wt. % a first liquid soluble to the polymer matrix and 10-40 wt. % a second liquid insoluble to the polymer matrix. The water-soluble substance is a water-soluble polymer, a low molecular weight water-soluble particle, or a mixture thereof. A method for producing the hollow fiber porous membrane using the composition including a) preparing the organic mixed solution, b) mixing the components of the composition, c) applying melt spinning, d) drawing, and e) washing. The hollow fiber membrane has high strength, large flux, and low cost.

Tianjin Polytechnic University | Date: 2013-01-24

A preparation method of a homogeneous-reinforced PVDF hollow fiber membrane includes steps of: a) preparing a reinforced matrix membrane, wherein a PVDF hollow fiber membrane is utilized as the reinforced matrix membrane; b) preparing a PVDF casting solution, wherein mass fractions of the PVDF casting solution are: PVDF 620 wt %; hydrophilic polymers or hydrophilic inorganic particles 0.62 wt %; pore-forming agent 610 wt %; and solvent 6887.4 wt %; mixing the above solutes in a water bath with a temperature of 7090 C., dissolving for 34 h with stirring, then deaerating under vacuum for obtaining the uniform PVDF casting solution; and c) preparing the homogeneous-reinforced membrane; wherein the PVDF casting solution is uniformly coated on an outer surface of the reinforced matrix membrane through a spinning spinneret, then the reinforced matrix membrane is towed by a filament guide roller in such a manner that the hollow fiber forms a membrane, then the membrane passes through an air gap with a length of 520 cm and is immersed in ultrafiltered water for coagulation, in such a manner that the homogeneous-reinforced membrane is obtained; wherein a traction speed is 525 cm/(rmin).

Feng N.,Tianjin Polytechnic University | Li J.,Tianjin Polytechnic University
Journal of Computational Physics | Year: 2013

Based on the stretched coordinate perfectly matched layer (SC-PML) formulations and the auxiliary differential equation (ADE) method, an efficient and unsplit-field implementation of the higher-order PML scheme with more than one pole is proposed to truncate the finite-difference time-domain (FDTD) lattices. The higher-order PML has the advantages of both the conventional PML and the complex frequency shifted PML (CFS-PML) in terms of absorbing performances. The proposed algorithm is validated through two numerical tests carried out in three dimensional and two dimensional domains. It is shown in the numerical simulations that the proposed PML formulations with the higher-order scheme are efficient in terms of attenuating both the low-frequency propagating waves and evanescent waves and reducing late-time reflections, and also hold much better absorbing performances than the conventional SC-PML and the convolutional PML (CPML) with the CFS scheme. © 2012 Elsevier Inc. Source

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