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Search Results: 1 - 10 of 18713 matches for " Guangcai Gao "
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Composition and spatial distribution pattern of ground-dwelling beetle communities in Yeyahu Wetland,Beiiing

Yu Wang,Guangcai Gao,Biqian Fu,Zhuan Wu,

生物多样性 , 2009,
Abstract: 2007年4–10月在北京野鸭湖湿地两种保存较好的湿地植被类型和3种主要的退化植被类型中设立了32个样地, 采用陷阱法调查地表甲虫群落的组成, 并在科级水平上探讨了湿地退化及植被类型变化对地表甲虫群落组成的影响。整个采样周期共采集甲虫标本42科, 其中步甲科和隐翅虫科为优势科, 蚁形甲科、肖叶甲科和薪甲科为亚优势科。在所研究的5种植被类型中, 湿地景观保存较好的芦苇(Phragmites communis)带与球穗莎草(Cyperus glomeratus)带的甲虫群落活动密度、科丰富度和Shannon-Wiener多样性指数(H’)均无显著差异, 而上述两种植被类型的甲虫活动密度以及球穗莎草带的甲虫科丰富度均显著高于3种退化的植被类型。对地表甲虫群落组成与9个环境因子进行的典范对应分析(CCA)表明, 32个样地在CCA排序图中的分布与植被类型之间存在明显的对应关系, 土壤含水量、植物盖度、植物生物量和枯落物盖度是影响地表甲虫群落组成及空间分布的主要环境因子。相关和回归分析结果也显示, 甲虫群落的活动密度与土壤含水量、植物生物量和植物盖度均极显著或显著正相关, 科丰富度与植物生物量显著正相关, 多样性指数(H’)与植物盖度极显著负相关; 其中土壤含水量的变化能够解释甲虫群落活动密度总方差的57%。此外, 通过主成分分析获得了反映土壤含水量、植物生物量和植物盖度综合作用的环境变量WBC (Water-Biomass-Coverage)。依据地表甲虫活动密度与WBC的关系, 可将5种植被类型分为彼此差异极显著的3组。研究结果表明保持良好的湿地景观对于保护湿地甲虫具有重要意义。
Thermodynamic Simulation of CCP in Air-Cooled Heat Pump Unit with HFCs and CO2 Trans-Critical  [PDF]
Feihu Chen, Shuguang Liao, Guangcai Gong
Journal of Power and Energy Engineering (JPEE) , 2018, DOI: 10.4236/jpee.2018.69012
Abstract: The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.

Cao Guangcai,

生态学报 , 1989,
Abstract: The ecological experiments of wheat in the hot summer was being carried out during 1982-1984 in Beijing. The date of sowing is in the first ten days of July every yaer. The strong springness wheat could get ears and ripeness with rapid growth and development. The plant is dwarfism with low 1000 seed Weight. Higher temperature and longer day-length could ensure and promote the growth and development of plant. The early stage of growth and development does not require low temperature and the vernalization does not occur in this ecotype of varieties. Sowing in the summer has great significance both in production and scientific research work.
Combined Natural Convection and Radiation Heat Transfer of Various Absorbing-Emitting-Scattering Media in a Square Cavity
Xianglong Liu,Guangcai Gong,Hengsheng Cheng
Advances in Mechanical Engineering , 2014, DOI: 10.1155/2014/403690
Abstract: A numerical model is developed to simulate combined natural convection and radiation heat transfer of various anisotropic absorbing-emitting-scattering media in a 2D square cavity based on the discrete ordinate (DO) method and Boussinesq assumption. The effects of Rayleigh number, optical thickness, scattering ratio, scattering phase function, and aspect ratio of square cavity on the behaviors of heat transfer are studied. The results show that the heat transfer of absorbing-emitting-scattering media is the combined results of radiation and natural convection, which depends on the physical properties and the aspect ratio of the cavity. When the natural convection becomes significant, the convection heat transfer is enhanced, and the distributions of and along the walls are obviously distorted. As the optical thickness increases, along the hot wall decreases. As the scattering ratio decreases, the along the walls decreases. At the higher aspect ratio, the more intensive thermal radiation and natural convection are formed, which increase the radiation and convection heat fluxes. This paper provides the theoretical research for the optimal thermal design and practical operation of the high temperature industrial equipments. 1. Introduction The combined heat transfer of the radiation and natural convection in the participating (absorbing-emitting-scattering) media is an important problem in the many fields of building and industry, including the boiler, furnace, building thermal comfort, and solar reactor. In the recent decades, the combined natural convection and radiation heat transfer has received the prominent interest and wide-spread research due to the wide industrial applications. Research on the numerical solution of heat transfer and fluid flow phenomena, where radiative heat transfer has an essential contribution, becomes a key aspect for the employment of CFD simulation, which always involve the solution of the Navier-Stokes equations (NSE) and the radiative transfer equation (RTE). Saravanan and Sivaraj [1] made a fundamental theoretical study to understand the interaction of surface radiation and natural convection in an air-filled cavity with a centrally placed thin heated plate. Sun et al. [2] studied the effects of radiation interchanges amongst surfaces on the transition from steady, symmetric flows about the cavity centerline to complex periodic flows. Mondal and Li [3] theoretically studied the effect of volumetric radiation on natural convection in a square cavity by using lattice Boltzmann method (LBM) with nonuniform lattices. Hou and
Discrete Boltzmann model of compressible flows with spherical or cylindrical symmetry
Aiguo Xu,Guangcai Zhang,Chuandong Lin
Physics , 2014,
Abstract: To study simultaneously the hydrodynamic and thermodynamic behaviors in compressible flow systems with spherical or cylindrical symmetry, we present a theoretical framework for constructing Discrete Boltzmann Model(DBM) with spherical or cylindrical symmetry in spherical or cylindrical coordinates. To this aim, a key technique is to use \emph{local} Cartesian coordinates to describe the particle velocity in the kinetic model. Thus, the geometric effects, like the divergence and convergence, are described as a \textquotedblleft force term\textquotedblright . Even though the hydrodynamic models are one- or two-dimensional, the DBM needs a Discrete Velocity Model(DVM) with 3 dimensions. We use a DVM with 26 velocities to formulate the DBM which recovers the Navier-Stokes equations with spherical or cylindrical symmetry in the hydrodynamic limit. For the system with \emph{global} cylindrical symmetry, we formulated also a DBM based on a DVM with 2 dimensions and 16 velocities. In terms of the nonconserved moments, we define two sets of measures for the deviations of the system from its thermodynamic equilibrium state. The extension of current model to the multiple-relaxation-time version is straightforward.
Discrete Boltzmann modeling of liquid-vapor system
Aiguo Xu,Guangcai Zhang,Yanbiao Gan
Physics , 2014,
Abstract: We further probe the Discrete Boltzmann Modeling(DBM) of the single-component two phase flows or the liquid-vapor system. There are two kinds of nonequilibrium effects in the system. The first is the Mechanical NonEquilibrium(MNE). The second is the Thermodynamic NonEquilibrium(TNE). The MNE is well described in the traditional fluid dynamic theory. The description of TNE resorts to the gas kinetic theory. Since based on the Boltzmann equation, the DBM makes possible to analyze both the MNE and TNE. The TNE is the main discussion of this work. A major purpose of this work is to show that the DBM results can be used to confirm and/or improve the macroscopic modeling of complex system.
地质学报 , 2013,
Discussion on Role of Forest to Control Agricultural Non-Point Source Pollution in Taihu Lake Basin-Based on Source-Sink Analysis  [PDF]
Jianfeng ZHANG, Jingmin JIANG, Zhijian ZHANG, Qihua SHAN, Guangcai CHEN, Ying WANG, Yonghui XU, Harry WU, Aljoy ABARQUEZ
Journal of Water Resource and Protection (JWARP) , 2009, DOI: 10.4236/jwarp.2009.15041
Abstract: Taihu Lake is located at the center of Changjiang delta region, the Lake and its effluent rivers are important water sources for 40 million around inhabitants and rapidly increasing industrial factories in Shanghai, Ji-angsu and Zhejiang. The pollutants originate mainly from acidy rain, home sewage of the vast number of inhabitants, livestock manure, agricultural fertilizers & pesticides applied over fields in the drainage basin, and the industrial sewage. Due to the kinds of pollutants, the Lake water is getting highly eutrophic, with frequent blooms of blue-green algae. Compared with point-source pollutants, diffuse pollution is much com-plicated and difficult to control. Thus combating non-point pollution (NPP) is paid much great attention. Based on analysis on source-sink of NPP in Taihu Lake basin, it is concluded that the function of forests on NPP control is multiple and important by both source reduction and sink expansion. The primary objective of planting trees through constructing forested wetlands and establishing riparian forest buffers is to control soil & water erosion, decrease agrochemicals application, and improve farming conditions in the region of Taihu Lake basin. Moreover forests help to intercept acidy rain, protect streambanks, uptake nutrients, hold up pollutants and provide habitat for wildlife.
Time Series Analysis of Hand-Foot-Mouth Disease Hospitalization in Zhengzhou: Establishment of Forecasting Models Using Climate Variables as Predictors
Huifen Feng, Guangcai Duan, Rongguang Zhang, Weidong Zhang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087916
Abstract: Background Large-scale outbreaks of hand-foot-mouth disease (HFMD) have occurred frequently and caused neurological sequelae in mainland China since 2008. Prediction of the activity of HFMD epidemics a few weeks ahead is useful in taking preventive measures for efficient HFMD control. Methods Samples obtained from children hospitalized with HFMD in Zhengzhou, Henan, China, were examined for the existence of pathogens with reverse-transcriptase polymerase chain reaction (RT-PCR) from 2008 to 2012. Seasonal Autoregressive Integrated Moving Average (SARIMA) models for the weekly number of HFMD, Human enterovirs 71(HEV71) and CoxsackievirusA16 (CoxA16) associated HFMD were developed and validated. Cross correlation between the number of HFMD hospitalizations and climatic variables was computed to identify significant variables to be included as external factors. Time series modeling was carried out using multivariate SARIMA models when there was significant predictor meteorological variable. Results 2932 samples from the patients hospitalized with HFMD, 748 were detected with HEV71, 527 with CoxA16 and 787 with other enterovirus (other EV) from January 2008 to June 2012. Average atmospheric temperature (T{avg}) lagged at 2 or 3 weeks were identified as significant predictors for the number of HFMD and the pathogens. SARIMA(0,1,0)(1,0,0)52 associated with T{avg} at lag 2 (T{avg}-Lag 2) weeks, SARIMA(0,1,2)(1,0,0)52 with T{avg}-Lag 2 weeks and SARIMA(0,1,1)(1,1,0)52 with T{avg}-Lag 3 weeks were developed and validated for description and predication the weekly number of HFMD, HEV71-associated HFMD, and Cox A16-associated HFMD hospitalizations. Conclusion Seasonal pattern of certain HFMD pathogens can be associated by meteorological factors. The SARIMA model including climatic variables could be used as an early and reliable monitoring system to predict annual HFMD epidemics.
Multiple-relaxation-time lattice Boltzmann model for compressible fluids
Feng Chen,Aiguo Xu,Guangcai Zhang,Yingjun Li
Physics , 2009, DOI: 10.1016/j.physleta.2011.04.013
Abstract: We present an energy-conserving multiple-relaxation-time finite difference lattice Boltzmann model for compressible flows. This model is based on a 16-discrete-velocity model. The collision step is first calculated in the moment space and then mapped back to the velocity space. The moment space and corresponding transformation matrix are constructed according to the group representation theory. Equilibria of the nonconserved moments are chosen according to the need of recovering compressible Navier-Stokes equations through the Chapman-Enskog expansion. Numerical experiments showed that compressible flows with strong shocks can be well simulated by the present model. The used benchmark tests include (i) shock tubes, such as the Sod, Lax, Sjogreen, Colella explosion wave and collision of two strong shocks, (ii) regular and Mach shock reflections, and (iii) shock wave reaction on cylindrical bubble problems. The new model works for both low and high speeds compressible flows. It contains more physical information and has better numerical stability and accuracy than its single-relaxation-time version.
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