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scaling,optimisation,and application of vegetation canopy radiative transfer model at microclimate scale

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Building Simulation 2024年第10期17卷 1805-1821页

作者： Junru Yan Lihua Zhao Xiufeng Sun Huihui Zhao Haichao Zheng Yu Wang Key Laboratory of Agricultural Biosafety and Green Production of Upper Yangtze River(Ministry of Education) College of Horticulture and Landscape ArchitectureSouthwest UniversityChongqing 400715China State Key Laboratory of Subtropical Building and Urban Science School of ArchitectureSouth China University of TechnologyGuangzhou 510640China School of Architecture and Urban Planning Shandong Jianzhu UniversityJinan 250100China School of Advanced Agriculture and Bioengineering Yangtze Normal UniversityChongqing 408100China

Urban greenery is widely recognised as a strategy to mitigate urban overheating,and its shading capacity is crucial for improving microclimate and thermal ***,research on modelling the vegetation canopy radiation transfer(VCRT)process for the microscale is lacking,and most existing VCRT models are taken out from mesoscale *** this study,we used canopy morphology and structure as an entry point to construct a VCRT model for the microscale,from the mesoscale ***,100 m and 1000 m were defined as the critical scales by scaling,and the effect of leaf distribution on VCRT was *** VCRT model was made applicable to the microscale by introducing a scattered radiation source term and 6 leaf inclination distribution(LID)functions,and the results showed that the proposed model could improve the accuracy of canopy radiation absorptivity by about 11%.In addition,both leaf area index(LAI)and LID had significant effects on VCRT,and vegetation with LAI above 2 and spreading leaves had better shading *** is worth noting that urban greenery has an exciting potential for thermal comfort improvement,with the potential to regulate even extremely hot weather from near"very hot"(148 W/m^(2))to almost"comfortable"(69 W/m^(2)).This study is a catalyst for improving the predictability of the VCRT process for microclimate and thermal comfort,providing theoretical support and implications for mitigating urban overheating and enhancing urban thermal resilience.

关键词： vegetation canopy radiative transfer scaling microclimate thermal comfort

scaling and Removal of Calcium. Carbonate on Electroless Plating Surface

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Chinese Journal of Chemical Engineering 2001年第2期9卷 150-155页

作者：杨庆峰丁洁沈自求 InstituteofRefrigerationandCryogenicEngineering ShanghaiJiaotongUniversityShanghai200030China InstituteofChemicalEngineering DalianUniversityofTechnologyDalian116012China

The scaling process of calcium carbonate on a low-energy heat transfer surface－electroless plating surface was investigated in a simulated cooling water system. Owing to the very low surface energy, the electroless plating surface exhibited less scaling susceptibility. A longer induction period and a lower scaling rate were obtained on the low-energy surface compared to copper surface under identical conditions. The calcite particles obtained on the electroless plating surface during the induction period were larger in size than those on copper surface because fewer crystals formed and grew at the same time on the low-energy surface. With increasing surface temperature, the induction period reduced and the scaling rate increased for the low-energy surface. When initial surface temperature was fixed, an increase in fluid velocity would reduce the induction period and increase the scaling rate due to the diffusion effect. However, when the heat flux was fixed, an increase in fluid velocity would decrease the surfacetemperature, and lead to a longer induction period and a lower scaling rate. The removal experiments of calcium carbonate scale indicated that during post induction period, the detachment was not obvious, while during the induction period, apparent removal of crystal particles was obtained on the electroless plating surface owing to the weak adhesion force. The more frequently the transient high hydrodynamic force acted, the more the detached crystal particles were.

关键词： scaling induction period removal electroless plating surface

scaling analysis of current influence on Hastelloy surface roughness in electro-polishing process

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Rare Metals 2019年第2期38卷 142-150页

作者： Feng Feng Xiang-Song Zhang Ti-Ming Qu Yan-Yi Zhang Xiang Qian Bin-Bin Liu Jun-Long Huang Ping-Fa Feng Division of Advanced Manufacturing Graduate School at Shenzhen Tsinghua University The State Key Laboratory of Tribology Department of Mechanical Engineering Tsinghua University Department of Physics Tsinghua University

In this study, a series of Hastelloy tapes were electro-polished, and the dividing method was used to carry out a detailed investigation on the influence of polishing current(I) on root mean square(R_q) at various image scales(L). The electro-polishing is found to be effective mainly at L smaller than 10μm, where the R_q–I relationship could be fitted by an exponential decay function with a residual roughness value. An approximate model of electro-polishing process was established to interpret the exponential decay function. This study provides a quantified insight into the electro-polishing process, which could help to obtain more understanding of its mechanism.

关键词： Surface roughness scaling analysis Root mean square Atomic force microscopy Electro-polishing

scaling of the flowfield in a combustion chamber with a gas-gas injector

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Chinese Physics B 2010年第1期19卷 575-588页

作者：汪小卫蔡国飙金平 School of Astronautics Beijing University of Aeronautics and Astronautics

The scaling of the flowfield in a gas gas combustion chamber is investigated theoretically, numerically and experimentally. To obtain the scaling criterion of the gas-gas combustion flowfield, formulation analysis of the threedimensional （3D） Navier-Stokes equations for a gaseous multi-component mixing reaction flow is conducted and dimensional analysis on the gas gas combustion phenomena is also carried out. The criterion implies that the size and the pressure of the gas gas combustion chamber can be changed. Based on the criterion, multi-element injector chambers with different geometric sizes and at different chamber pressures ranging from 3 MPa to 20 MPa are numerically simulated. A multi-element injector chamber is designed and hot-fire tested at five chamber pressures from 1.64 MPa to 3.68 MPa. Wall temperature measurements are used to understand the similarity of combustion flowfields in the tests. The results have verified the similarities between combustion flowfields under different chamber pressures and geometries, with the criterion applied.

关键词： scaling similarity gas gas combustion experiment

scaling properties of Navier-Stokes turbulence

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第3期10卷 392-397页

作者： Zhao-cun LIU School of Environment and Planning Henan University Kaifeng 475001 China

The property of the velocity field and the cascade process of the fluid flow are key problems in turbulence research. This study presents the scaling property of the turbulent velocity field and a mathematical description of the cascade process, using the following methods: (1) a discussion of the general self-similarity and scaling invariance of fluid flow from the viewpoint of the physical mechanism of turbulent flow; (2) the development of the relationship between the scaling indices and the key parameters of the She and Leveque (SL) model in the inertial range; (3) an investigation of the basis of the fractal model and the multi-fractal model of turbulence; (4) a demonstration of the physical meaning of the flowing field scaling that is related to the real flowing vortex. The results illustrate that the SL model could be regarded as an approximate mathematical solution of Navier-Stokes (N-S) equations, and that the phenomena of normal scaling and anomalous scaling is the result of the mutual interactions among the physical factors of nonlinearity, dissipation, and dispersion. Finally, a simple turbulent movement conceptional description model is developed to show the local properties and the instantaneous properties of turbulence.

关键词： Transformation equations scaling Spiral structure Cascade Turbulence

scaling of maximum probability density function of velocity increments in turbulent Rayleigh-Bénard convection

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Journal of Hydrodynamics 2014年第3期26卷 351-362页

作者：邱翔黄永祥周全孙超 School of Science Shanghai Institute of Technology Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Physics of Fluids Group University of Twente

In this paper, we apply a scaling analysis of the maximum of the probability density function（pdf） of velocity increments, i.e., max（） = max（）up p u, for a velocity field of turbulent Rayleigh-Bénard convection obtained at the Taylor-microscale Reynolds number Re60. The scaling exponent is comparable with that of the first-order velocity structure function, （1）, in which the large-scale effect might be constrained, showing the background fluctuations of the velocity field. It is found that the integral time T（x/ D） scales as T（x/ D）（x/ D）, with a scaling exponent =0.25 0.01, suggesting the large-scale inhomogeneity of the flow. Moreover, the pdf scaling exponent （x, z） is strongly inhomogeneous in the x（horizontal） direction. The vertical-direction-averaged pdf scaling exponent （x） obeys a logarithm law with respect to x, the distance from the cell sidewall, with a scaling exponent 0.22 within the velocity boundary layer and 0.28 near the cell sidewall. In the cell＇s central region, （x, z） fluctuates around 0.37, which agrees well with （1） obtained in high-Reynolds-number turbulent flows, implying the same intermittent correction. Moreover, the length of the inertial range represented in decade（）IT x is found to be linearly increasing with the wall distance x with an exponent 0.65 0.05.

关键词： Rayleigh-Bénard convection scaling probability density function(pdf)

scaling study of the combustion performance of gas gas rocket injectors

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Chinese Physics B 2011年第6期20卷 293-304页

作者：汪小卫蔡国飙金平 School of Astronautics Beijing University of Aeronautics and Astronautics

To obtain the key subelements that may influence the scaling of gas-as injector combustor performance, the combustion performance subelements in a liquid propellant rocket engine combustor are initially analysed based on the results of a previous study on the scaling of a gas gas combustion fiowfield. Analysis indicates that inner wall friction loss and heat-flux loss are two key issues in gaining the scaling criterion of the combustion performance. The similarity conditions of the inner wall friction loss and heat-flux loss in a gas-gas combustion chamber are obtained by theoretical analyses. Then the theoretical scaling criterion was obtained for the combustion performance, but it proved to be impractical. The criterion conditions, the wall friction and the heat flux are further analysed in detail to obtain the specific engineering scaling criterion of the combustion performance. The results indicate that when the inner fiowfields in the combustors are similar, the combustor wall shear stress will have similar distributions qualitatively and will be directly proportional to pc0.8dt-0.2 quantitatively. In addition, the combustion peformance will remain unchanged. Furthermore, multi-element injector chambers with different geometric sizes and at different pressures are numerically simulated and the wall shear stress and combustion efficiencies are solved and compared with each other. A multi- element injector chamber is designed and hot-fire tested at several chamber pressures and the combustion performances are measured in a total of nine hot-fire tests. The numerical and experimental results verified the similarities among combustor wall shear stress and combustion performances at different chamber pressures and geometries, with the criterion applied.

关键词： scaling combustion performance subscale combustor wall friction gas-gas combustion

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scaling Behavior and Magnetic Properties for Sm_x Co_5 Films

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Journal of Rare Earths 2006年第z2期24卷 266-269页

作者：李加新王锋赖恒郑卫峰贾翠红盖荣权黄志高 Department of Physics Fujian Normal University Department of Physics Quanzhou Normal College

SmxCo5(x = 1.3, 0.7, 0.4) thin films were prepared by magnetron co-sputtering technique. The samples were annealed at 723 K under Ar atmosphere. The annealed time was chosen as 30 min. The hysteresis loops of the samples were measured under the ac applied magnetic field with the period Tp(2πω) , H(t) = H0sin(ωt), by vibrating sample magnetometer (VSM). The experimental results indicate that, (1) the average hysteresis loop areas as functions of the values of H0 andωdisplay a power scaling law with the exponents, A = A0 + H0αωβ; (2) the x composition of SmxCo5 film has evident effect on the scaling behavior and magnetic properties; (3) the anisotropy scaling exponents exist clearly in the anisotropy SmxCo5 thin films. Moreover, the scaling behavior of the anisotropy magnetic film was also simulated with Monte Carlo method. The simulated results are consistent with the experimental fact.

关键词： SmCo films hysteresis scaling rare earths

scaling Laws of Heat Flux Width in the HL-2A Closed Divertor Tokamak

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Chinese Physics Letters 2022年第11期39卷 37-41页

作者： Longwen Yan Jinming Gao Xianggan Miao Zhihui Huang Na Wu Wenjin Chen Ting Wu Weice Wang Liang Liu Xiaoxue He Kaiyang Yi Yu He Lin Nie Zhongbing Shi Wulv Zhong Southwestern Institute of Physics Chengdu 610225China

The scaling law of divertor heat flux width is one of the key topics of magnetic confinement fusion,which is almost inversely proportional to the poloidal magnetic field on some opened divertor *** work focuses on the scaling laws of the closed divertor heat flux width in the HL-2 A tokamak under different discharge conditions,such as the Ohmic,L-and *** results indicate that there are basic similarities of the scaling laws of the heat flux width between the opened and closed ***,a larger spreading width in the private flux region is found,which is relevant to a small expansion factor of the magnetic flux in the closed divertor.

关键词： tokamak magnetic scaling