scholarly journals Introduction of Fractal-Based Tree Digitalization and Accurate In-Canopy Radiation Transfer Modelling to the Microclimate Model ENVI-met

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 869
Author(s):  
Helge Simon ◽  
Tim Sinsel ◽  
Michael Bruse

While complex urban morphologies including different materials, wall structures, etc., are rather adequately represented in microclimate models, replication of actual plant geometry is—so far—rather crudely handled. However, plant geometry greatly differs within species and locations while strongly determining a plant’s microclimate performance. To improve the plants representation in numerical models, a new method to describe plant skeletons using the so-called Lindenmayer-System has been implemented in the microclimate model ENVI-met. The new model allows describing much more realistic plants including the position and alignment of leaf clusters, a hierarchical description of the branching system and the calculation of the plant’s biomechanics. Additionally, a new canopy radiation transfer module is introduced that allows not only the simulation of diffuse radiation extinction but also secondary sources of diffuse radiation due to scattering of direct radiation within plant canopies. Intercomparisons between model runs with and without the advancements showed large differences for various plant parameters due to the introduction of the Lindenmayer-System and the advanced radiation scheme. The combination of the two developments represents a sophisticated approach to accurately digitize plants, model radiative transfer in crown canopies, and thus achieve more realistic microclimate results.

2019 ◽  
Author(s):  
Hou Jiang ◽  
Ning Lu ◽  
Jun Qin ◽  
Ling Yao

Abstract. Surface solar radiation drives the water cycle and energy exchange on the earth's surface, being an indispensable parameter for many numerical models to estimate soil moisture, evapotranspiration and plant photosynthesis, and its diffuse component can promote carbon uptake in ecosystems as a result of improvements of plant productivity by enhancing canopy light use efficiency. To reproduce the spatial distribution and spatiotemporal variations of solar radiation over China, we generate the high-accuracy radiation datasets, including global solar radiation (GSR) and the diffuse radiation (DIF) with spatial resolution of 1/20 degree, based on the observations from the China Meteorology Administration (CMA) and Multi-functional Transport Satellite (MTSAT) satellite data, after tackling the integration of spatial pattern and the simulation of complex radiation transfer that the existing algorithms puzzle about by means of the combination of convolutional neural network (CNN) and multi-layer perceptron (MLP). All data cover a period from 2007 to 2018 in hourly, daily total and monthly total scales. The validation in 2008 shows that the root mean square error (RMSE) between our datasets and in-situ measurements approximates 73.79 W/m2 (0.27 MJ/m2) and 58.22 W/m2 (0.21 MJ/m2) for GSR and DIF, respectively. Besides, the spatially continuous hourly estimates properly reflect the regional differences and restore the diurnal cycles of solar radiation in fine scales. Such accurate knowledge is useful for the prediction of agricultural yield, carbon dynamics of terrestrial ecosystems, research on regional climate changes, and site selection of solar power plants etc. The datasets are freely available from Pangaea at https://doi.org/10.1594/PANGAEA.904136 (Jiang and Lu, 2019).


1995 ◽  
Vol 43 (10-11) ◽  
pp. 1479-1483 ◽  
Author(s):  
A. Jurewicz ◽  
V. Orofino ◽  
A. Blanco ◽  
S. Fonti

Author(s):  
German Malikov ◽  
Alexandr Titaev ◽  
Vladimir Lisienko ◽  
Raymond Viskanta

A new and simple expression for the calculation of the total gas emittance of H2O-CO2 mixtures for modeling radiation transfer in combustion furnaces is presented. Its accuracy is established by comparing the predictions with those based on the well established exponential wide band model. The computational time was found to be reduced by a factor of 10–30 in comparison to other methods for computing the total emittance of combustion gas mixtures.


2015 ◽  
Author(s):  
C. Louise Campbell ◽  
Craig Christison ◽  
C. Tom A. Brown ◽  
Kenneth Wood ◽  
Ronan M. Valentine ◽  
...  

2015 ◽  
Vol 67 (4) ◽  
pp. 62 ◽  
Author(s):  
Satoshi Tanaka ◽  
Kohji Yoshikawa ◽  
Takashi Okamoto ◽  
Kenji Hasegawa

Author(s):  
Minjuan He ◽  
Xiaofeng Sun ◽  
Zheng Li

This paper presents the direct displacement-based design (DDD) procedure, structural modelling method, and structural performance calibration for post-tensioned CLT shear wall structures (PT-CLTstrs). Numerical models of the post-tensioned (PT) CLT shear walls were developed and calibrated with the experimental results. Based on the developed shear wall models, parametric analysis were conducted to investigate the lateral performance influencing factors. Then, a DDD procedure was developed and demonstrated by the design examples of a set of 8-, 12-, and 16-storey PT-CLTStrs. The corresponding simplified structural models were developed, and then a series of pushover and time-history dynamic analysis were conducted to calibrate the calculated structural performance objectives with the design targets of the DDD procedure. Finally, the empirical cumulative distribution functions (CDFs) of the maximum inter-storey drift (MaxISDR) were constructed. It is found that when the width of the PT CLT shear walls increases from 1.8 m to 3.0 m, the base shear at the drift of 2.0 % increases by twice accordingly. When the diameter of the PT strand increases from 15.2 mm to 34.6 mm, the base shear at the drift of 2.0 % increases by up to five times. Additionally, the MaxISDR limitation of the PT-CLTStrs is recommended as 2.2 % under the collapse prevention (CP) hazard level. The study results can serve as guidelines for the development of engineering design methods for the PT-CLTStrs.


Sign in / Sign up

Export Citation Format

Share Document