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Zhang X.,Tianjin Polytechnic University | Li W.,Tianjin Institute of Urban Construction
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

Based on parametric asymmetric blunt trailing-edge airfoil, the effects of trailing-edge thickness and its distribution ratio on aerodynamic performance of wind turbine airfoil were studied. The parametric expressions of asymmetric blunt trailing-edge modification profiles of S834 airfoil were established using the spline function. The lift and drag coefficients, lift-drag ratio, and airfoil surface pressure coefficient were calculated by XFOIL. The results show that when trailing-edge thickness increases, the lift coefficient increases after certain attack angle, and it is more obvious that the drag coefficients of modified airfoils are higher than that of original airfoil, and the lift-drag ratio increases first and then decreases. The lift coefficient in certain range of attack angle and the lift-drag ratio increase with the increasing of the trailing-edge thickness distribution ratio of the lower surface. The best trailing-edge thickness and distribution ratio are 2%c and 1 3, respectively. The research provides significant guidance for designing and optimizing blunt trailing-edge airfoil of wind turbine blade. Source

Wang A.,Tohoku University | Wang A.,CAS Research Center for Eco Environmental Sciences | Li Y.-Y.,Tohoku University | Li Y.-Y.,Tianjin Institute of Urban Construction | Estrada A.L.,Tohoku University
Applied Catalysis B: Environmental

The mineralization of antibiotic sulfamethoxazole (SMX) of concentrations up to 300mgL-1 was examined by photoelectro-Fenton (PEF) using an activated carbon fiber (ACF) cathode with UVA (365nm) irradiation. Comparative mineralization has been studied by different methods: RuO2/Ti anodic oxidation (AO), AO in the presence of electrogenerated H2O2 (AO-H2O2), AO-H2O2 in the presence of UVA (AO-H2O2-UVA), and both the electro-Fenton (EF) and PEF processes. PEF treatment at a low applied current of 0.36A yields a faster and more complete depollution with 80% of the TOC removed after 6h of electrolysis. The higher oxidative ability of the PEF process can be attributed to the additional hydroxyl radicals (·OH) produced by the photo-Fenton reaction. The 63% mineralization in the case of EF treatment was due to the formation of short intermediates, such as carboxylic acids, which were difficult to oxidise with ·OH. In the AO-H2O2-UVA process, about 36% of the TOC was removed after 6h electrolysis, while 28% of the TOC was removed in the AO-H2O2 process. SMX is only slightly mineralized by the AO process, with only 25% of the TOC removed. HPLC-MS analysis allowed for up to six aromatic reaction products to be identified during the SMX degradation in the PEF process, mainly formed from the hydroxylation of the aromatic ring or/and isoxazole ring, accompanied by the substitution of the amine group (on aromatic cycle) or methyl group (on isoxazole ring) by ·OH. The carboxylic acids generated, including oxalic, maleic, oxamic, formic and acetic acids, were detected by ion-exclusion chromatography. The initial organic nitrogen was mainly converted into NH4 + along with a very small proportion of NO3 - ion. Considering all the oxidation intermediates and end products for SMX degradation in the PEF process, a general mineralization mechanism by ·OH and UVA was proposed. © 2010 Elsevier B.V. Source

Zhang H.D.,Tianjin Institute of Urban Construction | Wang Y.F.,Beijing Jiaotong University
Steel and Composite Structures

As an alternative to current conventional force-based assessment methods, the energy-based seismic performance of a code-designed 20-storey high-rise steel building is evaluated in this paper. Using 3D nonlinear dynamic time-history method with consideration of additional material damping effect, the influences of different restoring force models and P-Δ /δ effects on energy components are investigated. By combining equivalent viscous damping and hysteretic damping ratios of the structure subjected to strong ground motions, a new damping model, which is amplitude-dependent, is discussed in detail. According to the analytical results, all energy components are affected to various extents by P-Δ /δ effects and a difference of less than 10% is observed; the energy values of the structure without consideration of P-Δ /δ effects are larger, while the restoring force models have a minor effect on seismic input energy with a difference of less than 5%, but they have a certain effect on both viscous damping energy and hysteretic energy with a difference of about 5~15%. The paper shows that the use of the hysteretic energy at its ultimate state as a seismic design parameter has more advantages than seismic input energy since it presents a more stable value. The total damping ratio of a structure consists of viscous damping ratio and hysteretic damping ratio and it is found that the equivalent viscous damping ratio is a constant for the structure, while the equivalent hysteretic damping ratio approximately increases linearly with structural response in elasto-plastic stage. Source

Pan L.,Tianjin Institute of Urban Construction
International Journal of Engineering, Transactions B: Applications

This paper proposes a novel analysis method for inner resistances of photovoltaic (PV) module. The main objectives are to obtain the resistance parameters of PV modules by adjusting I-V equation and voltage equation of diode and to find the relationship between resistance parameters and power. Firstly, values of serial and parallel resistance at maximum power point are concluded. Secondly, the curves of serial and parallel resistance are obtained when load increased from zero to infinity. Thirdly, the relationship between parallel resistance and power is obtained and the influence caused by ignorance of resistances is analyzed. Finally, simulation and experimental results of photovoltaic module show that the method is correct and feasible. Source

Chen J.,Tianjin Institute of Urban Construction
Journal of Theoretical and Applied Information Technology

It is well known that solutions of k-means algorithm depend on the initialization of cluster centers and the final solution converges to local minima. In this paper, we introduce a clustering approach that combines ideas from modified particle swarm optimization (PSO) and k-means. The potential benefits of this technique are investigated by incorporating the multidimensional asynchronism and stochastic disturbance method to the velocity in the particle swarm optimizer to create new modifications of the clustering for k-means algorithmic model, which could keep populations diversity and ability of search global optimum as well as solve the problem of the curse of dimensionality. The simulation results of web log dataset show that the proposed algorithm, compared with the five previous developed PSO techniques, provides enhanced performance and maintains more diversity in the swarm. © 2005 - 2012 JATIT & LLS. All rights reserved. Source

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