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Seasonal and Tissue Age Influences on Endophytic Fungi of Pinus tabulaeformis (Pinaceae) in the Dongling Mountains, Beijing

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Journal of Integrative Plant Biology 2008年第8期50卷 997-1003页

作者： Liang-Dong guo guo-Rui Huang yu wang Systematic Mycology and Lichenology Laboratory Institute of Microbiology the Chinese Academy of Sciences Beijing 100101 China

Endophytic fungi associated with Pinus tabulaeformis Carr. were investigated in the Dongling Mountains of Beijing. A total of 16200 tissue segments of P. tabulaeformis from four sample collections were processed, and 10659 fungal isolates were recovered. The overall colonization and isolation rates of endophytic fungi from high to low were spring〉winter〉autumn〉summer and in different tissues were bark〉needle〉xylem, irrespective of sampling seasons. The colonization rates of endophytic fungi of needles increased with age in the four sample collections. There were no significant differences of the colonization rates of endophytic fungi among 1-, 2-, and 3-year-old bark and xylem, except for significantly lower colonization rates in 1-year-old bark than in 2- and 3-year-old bark in summer. A similar trend of the isolation rates of endophytic fungi occurred. A total of 24 fungal taxa were recorded, of these five taxa Alternaria alternata, Leptostroma sp., Pestalotiopsis besseyi, Phoma lingam, and Phomopsis archeri, were consistently isolated as the common fungi in each sample collection. Our results suggest that some fungi show a certain degree of tissue recurrence or specificity, and the composition of endophytic assemblages is not conspicuously influenced by the seasonal factor.

关键词： colonization and isolation rates endophyte pine season tissue

Experimental Investigation of fluid-structure interaction of composite hydrofoils in cavitating flow

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Journal of Hydrodynamics 2022年第2期34卷 207-213页

作者： Hou-sheng Zhang Zhi-pu guo Qin Wu Han-zhe Zhang guo-yu wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China Aviation Engineering School Air Force Engineering UniversityXian710038China

This paper experimentally studies the cavitating fluid-structure interaction of composite hydrofoils with different ply *** synchronous measurement system with high-speed camera and for laser Doppler vibrometer(LDV),the feedback pressure regulation system,and the flow rate control system are *** experimental results of the cavitation evolution show that,compared with the rigid hydrofoil,the composite hydrofoils with+45°ply angle and 0°ply angle accelerate the cavitation inception,and the composite hydrofoil with−45°ply angle delays the cavitation *** the same cavitation number,the cloud cavitation of the+45°laminated hydrofoil is the most severe,followed by that of the 0°laminated hydrofoil,and that of the−45°laminated hydrofoil is relatively weak and close to that of the rigid *** analyses of the structural vibration of the composite hydrofoils in different cavitation stages show that the three composite hydrofoils have no significant vibration at the incipient cavitation and the supercavitation,but relatively significant vibration is observed in the sheet and cloud *** vibration amplitude of the composite hydrofoil with+45°ply angle is the largest,followed by those of the−45°,0°laminated *** the sheet cavitation,the dominant frequencies of the structural vibration velocity of the+45°laminated hydrofoil and the−45°laminated hydrofoil are the first and second modal frequencies,but no explicit dominant frequency is observed for the 0°laminated *** the cloud cavitation,the dominant frequencies of the three composite hydrofoils mainly include the first modal frequency,the second modal frequency,and the cavity shedding frequency.

关键词： Cavitation fluid-structure interaction composite hydrofoil cavity induced vibration

Experimental investigation of regular wave propagation over an idealized reef model

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Journal of Hydrodynamics 2020年第4期32卷 717-726页

作者： Gan-cheng Zhu Bing Ren Hong-jie Wen guo-yu wang Yong-xue wang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

The wave transformation over the deep-sea coral reefs is an essential issue in the analysis of the reef ecosystem and the design of large reef-top *** wave flume experiments are conducted to investigate the wave transformation processes over an idealized reef *** measurements of the wave height,the wave set-up and the wave-generated flow on the reef-top are made with and without the reef-top structure at various submerged depths and under different wave *** is found that the reef-top structure has a significant influence on the wave breaking,the wave set-up and the wave-generated *** wave set-up increases with the increasing wave height and the decreasing submergence ***,the relationship between the wave set-up and the wave period is complex,influenced by the reef-top structure.

关键词： Coral reef wave set-up reef-top structure wave breaking wave-generated flow

NUMERICAL SIMULATION OF HYDRODYNAMIC CHARACTERISTICS ON AN ARC CROWN WALL USING VOLUME OF FLUID METHOD BASED ON BFC

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Journal of Hydrodynamics 2011年第6期23卷 767-776页

作者： LI Xue-yan REN Bing wang guo yu wang Yong-xue State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116023China

In the present study, a new algorithm based on the Volume Of Fluid （VOF） method is developed to simulate the hydrodynamic characteristics on an arc crown wall. Structured grids are generated by the coordinate transform method in an arbitrary complex region. The Navier-Stokes equations for two-dimensional incompressible viscous flows are discretized in the Body Fitted Coordinate （BFC） system. The transformed SIMPLE algorithm is proposed to modify the pressure-velocity field and a transformed VOF method is used to trace the free surface. Hydrodynamic characteristics on an arc crown wall are obtained by the improved numerical model based on the BFC system （BFC model）. The velocity field, the pressure field and the time profiles of the water surface near the arc crown wall obtained by using the BFC model and the Cartesian model are compared. The BFC model is verified by experimental results.

关键词： Body Fitted Coordinate (BFC) SIMPLE scheme Volume Of Fluid (VOF) method arc crown wall staggered grid

Shape Descriptor with Morphology Method for Color-based Tracking

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International Journal of Automation and computing 2007年第1期4卷 101-108页

作者： Na wang guo-yu wang Information Science and Engineering School Ocean University of China Qingdao 266071 Shandong PRC

Tracking images using shape descriptor can be more accurate than using other existing methods and it is most useful when the environment is complex. However the existing methods with shape descriptor get more labeled parts to compare and detect the object in an image, which makes the computation more complicated. Thus, we need a trade-off between the accuracy and efficiency requirements. This paper aims to bridge this gap between the accuracy and efficiency requirements by using morphology method. To improve the original monochromatic object detecting system, we propose a new color descriptor to preprocess the image with polychromatic object. Experiments have been conducted and shown the proposed method has made a great improvement in the time complexity minimization comparing with the performances of the original detection algorithm.

关键词： Shape descriptor color descriptor morphology image tracking.

Enhanced thermoelectric performance of ternary compound Cu_(3)PSe_(4)by defect engineering

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Rare Metals 2020年第11期39卷 1256-1261页

作者： yu-Meng Zhang Xing-Chen Shen Yan-Ci Yan Gui-Wen wang guo-yu wang Jiang-yu Li Xu Lu Xiao-yuan Zhou Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials College of PhysicsChongqing UniversityChongqing401331China Chongqing Institute of Green and Intelligent Technology Chinese Academy of ScienceChongqing400714China University of Chinese Academy of Sciences Beijing100044China Analytical and Testing Center of Chongqing University Chongqing401331China Shenzhen Key Laboratory of Nanobiomechanics Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen518055China

The diamond-like compound Cu_(3)PSe_(4)with low lattice thermal conductivity is deemed to be a promising thermoelectric material,which can directly convert waste heat into electricity or vice versa with no moving parts and greenhouse ***,its performance is limited by its low electrical *** this study,we report an effective method to enhance thermoelectric performance of Cu_(3)PSe_(4)by defect *** is found that the carrier concentrations of Cu_(3-x)PSe_(4)(x=0,0.03,0.06,0.09,0.12)compounds are increased by two orders of magnitude as x>0.03,from 1×10^(17)to 1×10^(19)cm^(-3).Combined with the intrinsically low lattice thermal conductivities and enhanced electrical transport performance,a maximum zT value of 0.62 is obtained at 727 K for x=0.12 sample,revealing that Cu defect regulation can be an effective method for enhancing thermoelectric performance of Cu_(3)PSe_(4).

关键词： Cu_(3)PSe_(4) Thermal conductivity Defect engineering Electrical conductivity Thermoelectric performance

Cavitation vortex dynamics of unsteady sheet/cloud cavitating flows with shock wave using different vortex identification methods

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Journal of Hydrodynamics 2019年第3期31卷 475-494页

作者： Chang-chang wang Ying Liu Jie Chen Fu-yi Zhang Biao Huang guo-yu wang School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Cavitation is a complex multiphase flow phenomenon with an abrupt transient phase change between the liquid and the vapor, including multiscale vortical motions. The transient cavitation dynamics is closely associated with the evolution of the cavitation vortex structures. The present paper investigates the cavitation vortex dynamics using different vortex identification methods, including the vorticity method, the Q criterion method, the Omega method (Ω), the method and the Rortex method. The Q criterion is an eigenvalue-based criterion, and in the Ω method, the parameter is normalized, is independent of the threshold value and in most conditions Ω= 0.52 . The Rortex method is based on an eigenvector-based criterion. Numerical simulations are conducted using the implemented compressible cavitation solver in the open source software OpenFOAM for the sheet/cloud cavitating flows around a NACA66 (mod) hydrofoil fixed at a = 6°,= 1.25 and Re = 7.96 × 10^5 . The flow is characterized by the alternate interactions of the re-entrant flow and the collapse induced shock wave. Results include the vapor structures and the vortex dynamics in the unsteady sheet/cloud cavitating flows, with emphasis on the vortex structures in thecavitation region, the cavity interface, the cavity closure, the cavity wakes, and the foil wakes with the shedding cavity. The comparisons of the various methods, including that the vorticity method, the Q criterion method, the Ω method, the λ2 method and the Rortex method, show the performances of different methods in identifying the cavitation vortex structures. Generally, during the attached cavity growth stage, the Q criteria can well predict the vortex structures in the cavitation region and at the foil trailing edge in the pure liquid region, while with the Ω method and the Rortex method, the vortex structures outside the attached cavity and on the foil pressure side can also be predicted. The λ2 method can well predict the vortex structures in t

关键词： Cavitation vortex dynamics vortex identification sheet/cloud cavitating flow re-entrant jet shock wave OpenFOAM

On study of non-spherical bubble collapse near a rigid boundary

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Journal of Hydrodynamics 2020年第3期32卷 523-535页

作者： Xiao-jian Ma Xin Zhao Biao Huang Xiao-ying Fu guo-yu wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Department of Mechanics School of Aerospace EngineeringBeijing Institute of TechnologyBeijing100081China State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu 610065China

This paper applies numerical methods to investigate the non-spherical bubble collapse near a rigid boundary. A three-dimensional model, with the mass conservation equation reformulated for considering the compressibility effect, is built to deal with the coupling between the pressure and the flow velocity in the momentum and energy equations and to simulate the temporal evolution of the single bubble oscillation and its surrounding flow structure. The investigations focus on the global bubble patterns and its schlieren contours, as well as the high-speed jet accompanied when the bubble collapses and the counter jet is generated in the rebound stage. The results show that the robust pressure waves emitted due to the bubble collapse lead to substantial changes of the flow structures around the bubble, especially the formation of the counter jet generated in the rebound stage. Furthermore, compared with the high-speed jet when the bubble collapses, the counter jet in the rebound stage emits the momentum several times greater in the magnitude and in diametrically opposite direction at the monitoring point.

关键词： Bubble jet rigid boundary numerical simulation volume of fluid(VOF) pressure wave

Global cavitation and hydrodynamic characteristics of a composite propeller in non-uniform wake

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水动力学研究与进展B辑:英文版 2023年第3期35卷 498-515页

作者： Dan-dan Zhang Lu-lu Dong Qin Wu Jing Zhang guo-yu wang School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China China Academy of Launch Vehicle Technology Systems Engineering Division Beijing 100076China

The composite propeller has attracted much interest due to its excellent mechanical properties such as high specific stiffness and high specific strength,hence there is an increasing interest in utilizing the composite materials to improve the hydrodynamic and structural performance of marine *** objective of this paper is to study the cavitation performance of composite propellers based on the unsteady simulation method considering the cavitation-composite structure *** typical cavitation patterns around the composite propeller are studied,which include blade sheet cavitation and tip vortex *** unsteady flow characteristics of tip vortex cavitation and structural dynamic response of composite propeller are studied,and the mechanism of composite propeller for the cavitation suppression and efficiency improvement is *** results show that compared with rigid propellers,composite propellers have smaller cavity volume and higher propulsion efficiency under the same *** unsteady cavitating flow characteristics under non-uniform wake are periodic,and the phase lag of hydrodynamic coefficients of composite propeller can be observed compared with that of the rigid *** bending-torsional coupling deformation of the composite propeller makes the pressure pulsation of the flow field gentler,which reduces the influence of the cavitation load on the composite propeller.

关键词： Composite propeller unsteady cavitation hydrodynamic characteristics fluid-structure interaction(FSI)