Sha Y.,Zhejiang University of Science and Technology
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011
In order to research the performances and internal flow characteristics of vortex pump, the vortex pump suction, head and cavitation principles were illustrated, and the fact that q v-NPSH performance curve is falling parabolic was obtained after experiment on the vortex pump (32WB8-12) prototype and measurement of flow field in chamber with 5-hole spherical probe. Based on the simulation of the three-dimensional internal flow within vortex pump utilizing RNG k-ε turbulence model, the certain fidelity and accuracy of the numerical simulation results were verified by comparing between simulation and experiment. From these results, the conclusion is that the internal flow in vortex pump mainly consists of through flow, and the forced vortex is the main flow characteristics in the impeller region, and the flow in volute is similar to the combined vortex with backflow, circular flow and free vortex, which is non-axisymmetric unsteady flow with quite high turbulence intensity, and all these lead to the relative low efficiency of the vortex pump.
Ye C.-L.,Zhejiang University of Science and Technology |
Huang Q.,Zhejiang University of Science and Technology
Carbohydrate Polymers | Year: 2012
The response surface methodology was employed to study the extraction of polysaccharides from Scutellaria barbata D. Don. The quantitative effects of extraction temperature, time, number and ratio of water to raw material on yield of polysaccharides were investigated with Box-Behnken design. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and also analyzed using the appropriate statistical methods. By solving the regression equation and analyzing 3D plots, the optimum condition was at extraction temperature 70°C, time 3 h, numbers 3 and ratio of water to raw material 18.5 mL/g. Under these conditions, the experimental polysaccharides yield was 2.43 ± 0.11%, which was in good agreement with the predicted value. The antioxidant activities of the polysaccharides were evaluated in vitro. A potential antioxidant activity of S. barbata polysaccharides provides a scientific basis for the use of this herb in traditional medicine as an antioxidant. © 2012 Elsevier Ltd. All rights reserved.
Ge Z.,Zhejiang University of Science and Technology
Chemometrics and Intelligent Laboratory Systems | Year: 2014
In modern industries, the plant-wide process has become more and more popular, which always consists of various operation units, equipments, workshops and even factories. Therefore, it is more difficult to monitor those processes, and the monitoring complexity is also much higher. While the traditional multivariate statistical analysis provides satisfactory monitoring results within a single part, e.g. operation unit, it may fail to catch the detailed cross-information among different parts of the process. In this paper, an improved two-level monitoring system is formulated for plant-wide processes. In the first level, the latent variable information is extracted by the principal component analysis (PCA) model, based on which a global latent variable matrix is generated by combining latent variables from different parts of the process. In order to characterize the cross-data information of the plant-wide process, an efficient support vector data description (SVDD) method is employed for modeling the relationships among the global latent variable matrices. Based on the results of the Tennessee Eastman (TE) process, an enhanced performance is obtained by the improved two-level monitoring system. Compared to the traditional PCA based monitoring strategy, the new method is useful to describe the cross-data information of the plant-wide process, based on which more accurate monitoring results can be obtained. © 2014 Elsevier B.V.
Ye C.-L.,Zhejiang University of Science and Technology |
Jiang C.-J.,Zhejiang University of Science and Technology
Carbohydrate Polymers | Year: 2011
Polysaccharide production from the aerial parts of Plantaoo asiatica L. was carried out using water decoction. Response surface methodology (RSM), based on a five level, four variable central composite design (CCD), was employed to obtain the best possible combination of extraction time (X 1: 1-5 h), extraction temperature (X 2: 60-100 °C), number of extraction (X 3: 1-5), and ratio of water to raw material (X 4: 10-30) for maximum polysaccharide production. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis and also analyzed by appropriate statistical methods (ANOVA). The optimum extraction conditions were as follows: extraction time of 3.9 h, extraction temperature of 91 °C, number of extraction of 4, and ratio of water to raw material of 24. Under these conditions, the experimental yield was 4.37 ± 0.13%, which is well in close agreement with value predicted by the model. © 2010 Elsevier Ltd. All rights reserved.
Ye Y.,Zhejiang University of Science and Technology
Nonlinear Analysis: Real World Applications | Year: 2013
This paper deals with the initial-boundary value problem for a class of nonlinear higher-order Kirchhoff-type equation with dissipative term u tt+|A1/2u|2pAu+a|ut| q-2ut=b|u|r-2u, x∈Ω,t>0 in a bounded domain, where A=(-Δ)m, m>1 is a positive integer, a,b,p>0 and q,r>2 are constants. We obtain the global existence of solutions by constructing a stable set in H0m(Ω) and show the energy decay estimate by applying a lemma of V. Komornik. © 2013 Elsevier Ltd. All rights reserved.
Ge Z.,Zhejiang University of Science and Technology |
Song Z.,Zhejiang University of Science and Technology
Chemometrics and Intelligent Laboratory Systems | Year: 2013
Although successful application studies of independent component analysis (ICA) have been reported for non-Gaussian process monitoring, there are several drawbacks of this method, which make it cumbersome for practical utilization. First, due to the random initialization of the ICA algorithm, the monitoring performance of the ICA-based method is unstable, which may confuse the result. Second, the number selection of retained independent components (ICs) is still an open problem. Third, how to measure the importance of each IC for process monitoring purpose is also a difficult task so far. To address these issues, this paper intends to improve the ICA statistical monitoring method by incorporating the ensemble learning approach and the Bayesian inference strategy. Besides, a new performance-driven approach for IC number selection is also proposed. As a result, the stability of the non-Gaussian process monitoring result is greatly improved. Meanwhile, the monitoring performance is also boosted up, which is illustrated through the Tennessee Eastman (TE) benchmark case study. © 2013 Elsevier B.V.
Gu J.,Zhejiang University of Science and Technology
Energy Procedia | Year: 2011
In recent years, China's energy saving and emission reduction has achieved some success, But compared with the expected emission reduction targets, situation is still grim, In particular, there are still large deficiencies in standardized system, tax policy and government green procurement. China should commit to promote establishment of long-term mechanism of energy saving and emission reduction in the future, improve the work of standard system construction, tax policy innovation and strengthening to monitor government green procurement, in order to ensure the final realization of energy saving and emission reduction targets. © 2011 Published by Elsevier Ltd.
Guo S.H.,Zhejiang University of Science and Technology
Acta Mechanica | Year: 2011
The Maxwell's equation and stress equilibrium equation of anisotropic media, coupled to the heat conduction equation, are studied here based on the eigen theory of physical presentation, in which a new thermo-piezoelectric constitutive model is induced. The complete sets of uncoupled thermo-electromagnetic wave equations for piezoelectric solids are deduced. The results show that the equations of electromagnetic waves in anisotropic media subjected to heat become fourth order differential ones, and from them, a new phenomenon of thermo-electromagnetic waves with low propagation speed is obtained. In the final part of this paper, we discuss the propagation behavior of the new thermo-electromagnetic waves in the piezoelectric material of class 6 mm. © 2011 Springer-Verlag.
Wang R.,Zhejiang University of Science and Technology
Journal of Nanoparticle Research | Year: 2013
Droplet formation in the presence of nanoparticles was studied in a T-shaped microfluidic device numerically. Nanoparticles in continuous phase did not influence droplet formation dynamics obviously. Contrarily, the presence of nanoparticles in dispersed phase will influence evidently droplet formation dynamics, likely reasons are the accumulation of nanoparticles at the liquid-liquid interface leading to the variation of interfacial tension and the anisotropy of nanoparticles' movement at interface. The droplet size decreases almost linearly with increasing of the volume fraction of nanoparticles in dispersed phase when the volume fraction of nanoparticles not exceeding a critical value (about 0.2%), because very high concentration of nanoparticles results in particle aggregation so as to not decrease interfacial tension so obviously any more. A complicated mechanism of temperature influences on droplet formation may exist combining the variations of effective viscosity and interfacial tension. Discussions on microscopic mechanism of droplet formation in the presence of nanoparticles were carried out. © The Author(s) 2013.
Zhejiang University of Science and Technology | Date: 2014-09-01
The present disclosure discloses a device for biaxially-oriented stretching polytetrafluoroethylene hollow fiber membranes and the method thereof. The device may include a lubricant removing oven and a tube blank heating oven mounted at the outlet end of the push-compression mould, a core extension extending from the core into the lubricant removing oven and the tube blank heating oven, and a speed regulating guide wheel mounted at the outlet of the tube blank heating oven. A tube blank is extruded from a push-compression machine, inserted on the core extension for removal of lubricant in the lubricant removing oven, heated in the tube blank heating oven, transversely stretched by means of the bulked core, and then wound onto the speed regulating guide wheel for longitudinal stretching. Both transverse and longitudinal stretching can be realized for polytetrafluoroethylene tube blanks, overcoming disadvantages of traditional processing devices that can merely perform longitudinal stretching.