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Lei, Chu-Zhao,Zhang, Wei,Chen, Hong,Lu, Fan,Ge, Qing-Lan,Liu, Ruo-Yu,Dang, Rui-Hua,Yao, Yun-Yi,Yao, Li-Bo,Lu, Zi-Fan,Zhao, Zhong-liang Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.4
Little is known about the origin and genetic diversity of swamp buffaloes in China. To obtain more knowledge on genetics of the water buffalo in China, the complete mitochondrial D-loop sequences of 30 samples from 6 native types were investigated. The results revealed 12 mitochondrial haplotypes with 50 polymorphic sites. Among these polymorphic sites, there were 49 transitions and 1 transversion. The average nucleotide diversity and haplotype diversity estimated from mtDNA D-loop region in 6 Chinese water buffalo types were 0.00684 and 0.798, respectively, showing rather abundant mitochondrial genetic diversity. The Neighbor-Joining (NJ) tree of mtDNA of Chinese water buffaloes was constructed according to the 12 haplotypes. The NJ tree indicated two lineages being designated lineage A and lineage B, in which lineage A was predominant, and lineage B was at low frequency. The new lineage B was first discovered and defined in 6 Chinese water buffalo types. These results showed that two different maternal lineages were involved in the origin of domestic swamp buffaloes in China and the lineage B was probably an introgression from Southeast Asian buffaloes.
A design of transmission-type multi-target X-ray tube based on electric field modulation
Zhao, Lei,Jia, Wenbao,Jin, Limin,Shan, Qing,Cheng, Can,Zhu, Hongkui,Hei, Daqian Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.9
Multi-target X-ray tube is a new type X-ray source, and can be applied in many fields such as sensitive X-ray fluorescence analysis and medical imaging. In this work, we report an electric field modulation multi-target X-ray tube, which contains four targets (Cr, Ni, Au, Mo) coated on a Beryllium (Be) window. A four-valve electric field deflector was developed to deflect the electron beam to bombard the corresponding targets. Particle dynamics analysis software was employed to simulate the particle tracking of electron beam. The results show that the 30 keV electron beam could get a 6.7 mm displacement on the target plane by 10<sup>5</sup> V/m electric field. The focus areas are about 2 mm × 5 mm and 4 mm × 2.5 mm after deflection in two directions. Thermal behavior calculated by ANSYS shows that the designed target assembly could withstand a 10 W continuous power. The optimum target thicknesses and emission spectra were obtained by Geant4 when the thickness of Be window was 300 mm and the electron beam incident angle was 0.141 rad. The results indicate that this multi-target X-ray tube could provide different X-ray sources effectively.
CFD-DEM modeling of snowdrifts on stepped flat roofs
Lei Zhao,Zhixiang Yu,Fu Zhu,Xin Qi,Shichun Zhao 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.23 No.6
Snowdrift formation on roofs should be considered in snowy and windy areas to ensure the safety of buildings. Presently, the prediction of snowdrifts on roofs relies heavily on field measurements, wind tunnel tests and numerical simulations. In this paper, a new snowdrift modeling method by using CFD (Computational Fluid Dynamics) coupled with DEM (Discrete Element Method) is presented, including material parameters and particle size, collision parameters, particle numbers and input modes, boundary conditions of CFD, simulation time and inlet velocity, and coupling calculation process. Not only is the two-way coupling between wind and snow particles which includes the transient changes in snow surface topography, but also the cohesion and collision between snow particles are taken into account. The numerical method is applied to simulate the snowdrift on a typical stepped flat roof. The feasibility of using coupled CFD with DEM to study snowdrift is verified by comparing the simulation results with field measurement results on the snow depth distribution of the lower roof.
Zhao Lei,Wang Jianhua,Li Xiaofeng 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.6
The traditional Snake model and GVF-Snake model set high requirements on noise and initial contour in wood cell contour extraction. To solve this problem, on the premise of considering the image texture and gray-scale information, the area information is directly introduced into the active contour extraction model through force equilibrium equation. Experiments show that the contour extracted with this method is not only more close to real cell contour, but also improved in anti-noise property. In particular, in the convergence of high noise and deep sunken areas, it has some advantages not found in other traditional methods.
Research on Wood Cell Shape Analysis Methods based on Fourier Descriptors
Lei Zhao,Jian Hua Wang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.2
The shape parameter of wood microscopic cell is one of the important parameters in the identification of wood species. Fourier Descriptors is often used to describe the boundaries of closed areas. The paper analyzes the slice images of five kinds of common wood cells, extracting the mathematical parameters of the cells, obtaining the average value and simulating the benchmark cell shape of the five wood species to provide data support for subsequent recognition experiments.
Guided waves of porous FG nanoplates with four edges clamped
Zhao, Jing-Lei,She, Gui-Lin,Wu, Fei,Yuan, Shu-Jin,Bai, Ru-Qing,Pu, Hua-Yan,Wang, Shilong,Luo, Jun Techno-Press 2022 Advances in nano research Vol.13 No.5
Based on the nonlocal strain gradient (NSG) theory and considering the influence of moment of inertia, the governing equations of motion of porous functionally graded (FG) nanoplates with four edges clamped are established; The Galerkin method is applied to eliminate the spatial variables of the partial differential equation, and the partial differential governing equation is transformed into an ordinary differential equation with time variables. By satisfying the boundary conditions and solving the characteristic equation, the dispersion relations of the porous FG strain gradient nanoplates with four edges fixed are obtained. It is found that when the wave number is very small, the influences of nonlocal parameters and strain gradient parameters on the dispersion relation is very small. However, when the wave number is large, it has a great influence on the group velocity and phase velocity. The nonlocal parameter represents the effect of stiffness softening, and the strain gradient parameter represents the effect of stiffness strengthening. In addition, we also study the influence of power law index parameter and porosity on guided wave propagation.
Lei Zhao,Changqing Yuan,Ling Gao,Chengxi Zhang 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.2
The aim of this paper is to analyze dynamic characteristics and stability of magnetic sail-based planetary displaced orbits, and the feasibility of using a magnetic sail as an advanced propellantless control technology for formation flying around elliptic planetary displaced orbits (EPDOs). The thrust can be obtained from the momentum exchange between solar wind and an artificial magnetic field. First, the requirements of a magnetic sail for generating and maintaining a planetary circular displaced orbit is discussed including the value of attitude angles and characteristic acceleration. Based on different orbital periods, the circular displaced orbits are divided into three types and their linear stability is analyzed. For elliptical orbits, the conditions required to maintain an EPDO are investigated and the dynamical models of magnetic sail formation system are established. A finite time coordinated control algorithms relying on the protocols formulated on an undirected communication graph is proposed to achieve synchronized formation tracking rapidly while enhancing the robustness of formation system due to information interaction between spacecraft. Several numerical simulations are conducted to demonstrate that spacecraft formation can be effectively controlled by the proposed propellantless propulsion system.
An approach for failure analysis of composite bridge deck systems with openings
Zhao, Lei,Karbhari, Vistasp M. Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.1
Design details pertaining to the connection between some recently developed fiber reinforced polymer (FRP) composite deck systems and the supporting girders require openings through cells of the deck. This significantly changes the stress distribution in these components. As a result, the conventional assumptions that deck designs are controlled by their stiffness, and not strength, needs a closer examination. This paper proposes an analytical method to investigate the stress states and failure mechanisms using a type of "global-local" modeling perspective, incorporating classical lamination theory and first ply failure criterion with use of appropriate stress concentration factors around the cutouts. The use of a "smeared-stress" approach is presented as a potential means of simplifying certain FRP specific complexities, while still enabling prediction of overall failure.
African Maternal Origin and Genetic Diversity of Chinese Domestic Donkeys
Lei, Chu-Zhao,Ge, Qing-Lan,Zhang, Hu-Cai,Liu, Ruo-Yu,Zhang, Wei,Jiang, Yong-Qing,Dang, Rui-Hua,Zheng, Hui-Ling,Hou, Wen-Tong,Chen, Hong Asian Australasian Association of Animal Productio 2007 Animal Bioscience Vol.20 No.5
The origin of domestic donkeys in China has been controversial. To clarify the origin of Chinese domestic donkeys, we investigated the partial mitochondrial D-loop sequences of 126 samples from 12 native breeds. The results revealed two mitochondrial origins, lineage Somali and lineage Nubian of African wild ass detected in Chinese domestic donkeys. Lineage Somali was predominant in Chinese domestic donkey breeds. The pattern of genetic variation in ass mtDNA D-loop sequences indicated that the two lineages Somali and Nubian from China had undergone population expansion events. In a combined analysis of lineages Somali and Nubian between previously published sequences from other countries/regions and sequences of Chinese domestic donkeys, the results indicated that the two lineages of Chinese domestic donkeys were from Africa and supported the African maternal origins of Chinese domestic donkeys. There was no obvious geographical structure in Chinese domestic donkey breeds, but the population showed abundant mtDNA diversity. The spread routes of Chinese domestic donkeys were also discussed.