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Search Results: 1 - 10 of 26772 matches for " Yingzi Jin "
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Numerical Investigation on Vortex Structure and Aerodynamic Noise Performance of Small Axial Flow Fan  [PDF]
Li Zhang, Yingzi Jin
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A046
Abstract: The details of unsteady flow field in small axial fans are described and the relationship between the internal flow char- acteristics and aerodynamic noise of small axial flow fans are explored in the manuscript. Firstly, the broadband noise model is introduced to calculate the distributions of broadband noise sources in fan’s internal flow field, and further fan’s internal flow characteristics affecting broadband noise sources are analyzed by the main distributions of broad- band noise sources. Secondly, the unsteady characteristics of vortex structure in fan’s internal flow field are analyzed by large eddy simulation, and FH-W acoustic model is introduced to calculate aerodynamic noise affected by the unsteady characteristics of vortex structure. Finally, Monitoring points are set up near and far field of small axial fans, at which sound pressure level and spectral characteristics are analyzed. The results show that broadband noise sources are mainly distributed at the tip clearance close to blade trailing edge and one third of chord length of blade trailing edge of small axial fans. The maximum sound power of broadband noise sources at the tip clearance is greater than that at blade trail- ing edge. Sound power level of broadband noise near one third of blade chord length of blade trailing edge is first in- creasing and then decreasing when the distance between radial planes and the center of fan hub increases. Fan’s internal flow characteristics affecting broadband noise sources are the tip leakage vortex and the trailing edge vortex shedding. The tip leakage vortices at the leading edge of blade tip first integrate and then break down, while vortex cores of the trailing edge vortex shedding gradually move from blade hub to one-third of blade chord
Effect of Hub-Ratio on Performance of Asymmetric Dual-Rotor Small Axial Fan  [PDF]
Yongmin Wu, Yingzi Jin, Yuzhen Jin, Yanping Wang, Li Zhang
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32A013
Abstract: Currently, domestic and abroad scholars put more attention on contra-rotating dual-rotor axial fan. But there is less scholars study on asymmetric dual-rotor small axial fan, which is one of the contra-rotating dual-rotor axial fans. Like axial fan, many factors have influence on the performance of the asymmetric dual-rotor small axial flow fan, such as the wheel hub ratio, blade shape, blade number, stagger angle and the tip clearance. Because wheel hub ratio has great impact on the performance of the fan, we choose the size of wheel hub ratio as a variable factor to study the model change. There is a different wheel hub ratio between front stage impeller and rear stage of asymmetric dual-rotor small axial fan, so it is very beneficial to select the greater wind area that the fan area of external diameter minuses the area occupied by the blades and the hub as front stage impeller. In this paper, the hub-ratio of front stage impeller is 0.72, and that of rear stage is 0.72, 0.67 and 0.62 respectively along with the front stage impeller. Three kinds of models with different hub ratio of rear stage are simulated using the CFD software and the static characteristics are obtained. Based on the experimental test results, the internal flow field of the asymmetric dual-rotor small axial fan is analyzed in detail, the impact trends of different hub-ratio on the performance of asymmetric dual-rotor small axial fan are obtained and the argument of structure optimization for dual-rotor small axial fan is provided.
Numerical Study on Internal Flow of Small Axial Flow Fan with Splitter Blades  [PDF]
Lifu Zhu, Yingzi Jin, Yanping Wang, Li Zhang, Yuzhen Jin
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32A012
Abstract: The splitter blades are widely used in axial compressors and play an active role in the improvement of the overall performance of compressors. However, little research on the application of splitter blades to small axial flow fans is conducted. This paper designs a splitter blade small axial flow fan (model B) with a small axial flow fan as the prototype fan (model A) by adding short blades at the second half part of the passageway among long blades of model A. The steady simulation for the two models was conducted with the help of RNG k-ε turbulence model provided by software Fluent, and static characteristics and internal flow characteristics of the two models were compared and analyzed. Results show that splitter blades can improve the unsteady flow in the small flow rate region and also have a positive role to increase static pressure rise and efficiency in the higher flow rate region. The variation of static pressure gradient on the meridian plane in model B is well-distributed. The static pressure on the blade surface of model B distributes more uniformly. Splitter blades can suppress the secondary flow from pressure side to suction side in the leading edge because the pressure difference between suction side and pressure side in model B is generally lower than that of model A. And it also can restrain the vortex shedding and flow separation, and further it may be able to get the aerodynamic noise lower because static pressure gradient on the blade surface is well-distributed and the vortex shedding is not developed. Therefore, the performance of the fan with splitter blades is better than that of the prototype fan. The findings of this paper can be a basis for the design of high performance small axial flow fans.
Transient Hydraulic Performance and Numerical Simulation of a Centrifugal Pump with an Open Impeller during Shutting Down  [PDF]
Yuliang Zhang, Zuchao Zhu, Yingzi Jin, Baoling Cui
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A044
Abstract: In this paper, the transient behavior of a low specific speed centrifugal pump with straight blades during shutting down is studied through the experimental test, theoretical calculation, and numerical simulation. The variations of the rota- tional speed, flow rate, and head with time are obtained in experiment. Based on the experimental results of the rota- tional speed and flow rate, the additional theoretical heads are quantitatively calculated and analyzed. The experimental results of the rotational speed and flow rate are worked as the boundary conditions to accurately accomplish the nu- merical simulation of the transient flow during shutting down. The experimental results show that the decrease history of the flow rate evidently lags behind that of the rotational speed, while the rotational speed slightly lags behind the head. Theoretical analysis shows that there exists a clear negative head impact phenomenon in the process of stopping. The transient behavior of the centrifugal pump with straight blades mainly comes from the rotation deceleration of im- peller, and has nothing to do with the fluid deceleration. The numerical simulations show that a large area backflow can be seen when the rotational speed decreases to zero due to the flowing inertia. In conclusion, the numerical simulation of the flow field is in good agreement with the internal flow theory of centrifugal pumps.
Influence of Additional Device on Performance of the Marine Current Turbine  [PDF]
Baoling Cui, Zhiwei Song, Yuliang Zhang, Yingzi Jin, Yonggang Lin
Open Journal of Fluid Dynamics (OJFD) , 2012, DOI: 10.4236/ojfd.2012.24A037
Abstract: To investigate the influence of additional device on the flow in marine current turbine, two additional devices for ma- rine current turbine including short diffuser and long diffuser types are studied based on the test data of original marine current turbine. The results of numerical simulation show that the additional device with flange structure, compared to marine current turbine without additional device, can obtain more output power. However, it brings the inhomogeneity of additional device force as the increasing of effective output power. At same time, due to existence of the flange, two karman vortices are found behind the flange. The low pressure region produced by additional device and flange struc- ture can speed up the flow around the marine current turbine, so as to improve the output power.
Design of Half-Ducted Axial Flow Fan Considering Radial Inflow and Outflow  [PDF]
Pin Liu, Yusuke Oka, Yoichi Kinoue, Norimasa Shiomi, Toshiaki Setoguchi, Yingzi Jin
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32A001
Abstract:

Half-ducted fan and ducted fan have been designed and numerically analyzed for investigating the radial flow effect on the overall performance and the three dimensional flow field in design. Based on quasi-three dimensional flow theory, the meridional flow was calculated by adopting the radial balance equations, while the calculation of the blade to blade flow was obtained by 2D cascade data with the correction by a potential flow theory. Two types of axial flow fan were designed. One is the full ducted case as if it was in the straight pipe and another is the half-ducted case with the radial inflow and outflow. The previous experimental results of authors were used to decide the inclinations of both the inflow and outflow. And the circular arc blade with equal thickness was adopted. The numerical results indicate that both of the designed fans can reach the specified efficiency and also the efficiency surpasses more than 11%. Furthermore, the static pressure characteristic of half-ducted fan is much better than that of ducted fan. In comparison of the three dimensional internal flow of these two fans, the improvement of the flow angle at inlet and outlet, the distributions of velocity in the flow field and the pressure distributions on the blade surfaces can be achieved more successfully in accordance with the design intension on consideration of flow angle in design. The conclusion that half-ducted design with considering radial inflow and outflow is feasible and valid in comparison with ducted design for axial flow fans has been obtained at the end of the paper.

The Study on the Status and the Countermeasures of Low-carbon Financial System of China  [PDF]
Yuechun Wen, Yingzi Wu
Low Carbon Economy (LCE) , 2010, DOI: 10.4236/lce.2010.12009
Abstract: Low-carbon economy has become the inevitable choice for the future development of human society, and can not de-velop without the strong support from financing system. Based on foreign low-carbon finance development experience, through studying on the status and the existing problem of the development of the domestic low-carbon finance, it is found that it is very important to improve and perfect a low-carbon financial system for China, including the low-carbon financial institutions and products system, the low-carbon financial market system, the low-carbon finan-cial environment system and the supporting policies and measures system.
Advanced Image Processing for Defense and Security Applications
Eliza Yingzi Du,Robert Ives,Alan van Nevel,Jin-Hua She
EURASIP Journal on Advances in Signal Processing , 2010, DOI: 10.1155/2010/432972
Abstract:
Wnt signaling in development and disease
Yingzi Yang
Cell & Bioscience , 2012, DOI: 10.1186/2045-3701-2-14
Abstract: One of the most remarkable biological processes is the formation of a morphologically complex and functional diverse multicellular organism such as a human being from a single fertilized egg within a short period of time. During this tightly regulated process of embryonic morphogenesis, functional tissues and organs are formed and they have to be properly maintained during adult lives. Because cell-cell signaling plays essential and pivotal roles in both embryonic development and adult physiology, understanding the function and the underlying molecular mechanism of key cell signaling pathways in both development and diseases has been a major focus of our lab. Here we primarily focus on Wnt signaling in major developmental events of the skeletal system.Wnts are evolutionarily conserved major regulatory factors in both development and disease. Wnt signaling is required in most embryonic developmental processes in both invertebrates and vertebrates. Abnormal Wnt signaling causes many types of tumors [1-3]. For instance, ectopic activation of Wnt1 gene expression in the mouse mammary gland leads to tumor formation [4]. Mutations in Wnt signaling components have also been found to cause other human diseases. Weakened Wnt/β-catenin signaling leads to osteoporosis-pseudoglioma syndrome due to reduced bone mass [5] whereas enhanced Wnt/β-catenin signaling causes thick bone syndrome due to increased bone mass [6,7]. In addition, Robinow syndrome and Brachydactyly Type B1 that are characterized by shortened skeletal elements are caused by mutations in the Wnt/planar cell polarity pathway components [8-11].Wnts are a large family of secreted molecules that can signal through several distinct pathways (Figure?1). The β-catenin mediated Wnt/β-catenin pathway is also called the canonical pathway. This pathway is best understood and mainly controls cell proliferation and differentiation. Central to this pathway is the control of β-catenin stability. In the absence of Wnt signaling
Key Incorporation Scheme for Cancelable Biometrics  [PDF]
Eliza Yingzi Du, Kai Yang, Zhi Zhou
Journal of Information Security (JIS) , 2011, DOI: 10.4236/jis.2011.24018
Abstract: Biometrics is becoming an important method for human identification. However, once a biometric pattern is stolen, the user will quickly run out of alternatives and all the applications where the associated biometric pattern is used become insecure. Cancelable biometrics is a solution. However, traditional cancelable biometric methods treat the transformation process and feature extraction process independently. As a result, this kind of cancelable biometric approach would reduce the recognition accuracy. In this paper, we first analyzed the limitations of traditional cancelable biometric methods, and proposed the Key Incorporation Scheme for Cancelable Biometrics approach that could increase the recognition accuracy while achieving “cancelability”. Then we designed the Gabor Descriptor based Cancelable Iris Recognition method that is a practical implementation of the proposed Key Incorporation Scheme. The experimental results demonstrate that our proposed method can significantly improve the iris recognition accuracy while achieving “cancelability”.
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