Atmospheric Transmission of Ultraviolet and Total Solar Radiation by Clouds, Aerosols, and Ozone in Seoul, Korea: a Comparison of Semi-Empirical Model Predictions with Observations

2018 ◽  
Vol 55 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Hana Lee ◽  
Woogyung Kim ◽  
Yun Gon Lee ◽  
Jhoon Kim ◽  
Hi Ku Cho
Keyword(s):  
Solar Radiation ◽  
Empirical Model ◽  
Total Solar Radiation ◽  
Atmospheric Transmission ◽  
Model Predictions ◽  
Semi Empirical

scholarly journals Outdoor Air Temperature Measurement: A Semi-Empirical Model to Characterize Shelter Performance

Climate ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 26
Author(s):  
Jérémy Bernard ◽  
Pascal Kéravec ◽  
Benjamin Morille ◽  
Erwan Bocher ◽  
Marjorie Musy ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Response Time ◽  
Air Temperature ◽  
Empirical Model ◽  
Regression Coefficient ◽  
Radiation Sensitivity ◽  
Temperature Sensors ◽  
Outdoor Air ◽  
The One ◽  
Semi Empirical

Shelters used to protect air temperature sensors from solar radiation induce a measurement error. This work presents a semi-empirical model based on meteorological variables to evaluate this error. The model equation is based on the analytical solution of a simplified energy balance performed on a naturally ventilated shelter. Two main physical error causes are identified from this equation: one is due to the shelter response time and the other is due to its solar radiation sensitivity. A shelter intercomparison measurement campaign performed by the World Meteorological Organization (WMO) is used to perform a non-linear regression of the model coefficients. The regression coefficient values obtained for each shelter are found to be consistent with their expected physical behavior. They are then used to simply classify shelters according to their response time and radiation sensitivity characteristics. Finally, the ability of the model to estimate the temperature error within a given shelter is assessed and compared to the one of two existing models (proposed by Cheng and by Nakamura). For low-response-time shelters, our results reduce the root mean square error by about 15% (0.07 K) on average when compared with other compensation schemes.

scholarly journals Computational simulation of flocculent sedimentation based on experimental results

2012 ◽  
Vol 65 (6) ◽  
pp. 1007-1013 ◽  
Author(s):  
Mafeni S. Ramatsoma ◽  
Evans M. N. Chirwa
Keyword(s):  
Empirical Model ◽  
Mechanistic Model ◽  
Computational Simulation ◽  
Data Sets ◽  
Random Errors ◽  
Wide Range ◽  
Model Predictions ◽  
Sedimentation Basins ◽  
Semi Empirical ◽  
Better Than

Computerised interpolation algorithms as well as the empirical model for analysing the flocculent settling data were developed. A mechanistic semi-empirical model developed from fundamental physical principles of a falling particle in a viscous fluid was tested against actual flocculation column data. The accuracy of the mechanistic model was evaluated using the sum of the squared errors between the interpolated values (real values) and the model predictions. Its fitting capabilities were compared with Özer's model using nine flocculent data sets of which four were obtained from literature and the rest were actual data from the performed experiments. The developed model consistently simulated the flocculation behaviour of particles in settling columns better than Özer's model in eight of the nine data sets considered. It is recommended that the model's performance be further compared with other models like the Rule based and San's model. The errors due to the use of interpolated values when determining the performance of the empirical models need to be investigated. Furthermore, a three-way rather than two-way interpolation should now be achievable using the interpolation algorithm developed in this study thereby reducing the effects of interpolation bias. The above work opens the way to full automation of design of flocculation sedimentation basins and other gravitational particle separation systems which at present are designed manually and are susceptible to a wide range of human and random errors.

scholarly journals A semi-empirical model for estimating surface solar radiation from satellite data

2013 ◽  
Author(s):  
Serm Janjai ◽  
Somjet Pattarapanitchai ◽  
Rungrat Wattan ◽  
Itsara Masiri ◽  
Sumaman Buntoung ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Satellite Data ◽  
Empirical Model ◽  
Surface Solar Radiation ◽  
Semi Empirical

scholarly journals A Semi-Empirical Model for Predicting Frost Properties

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 412
Author(s):  
Shao-Ming Li ◽  
Kai-Shing Yang ◽  
Chi-Chuan Wang
Keyword(s):  
Thermal Conductivity ◽  
Linear Programming ◽  
Numerical Model ◽  
Empirical Model ◽  
Quantitative Method ◽  
Predictive Ability ◽  
Dimensionless Temperature ◽  
Crystal Shape ◽  
Proposed Model ◽  
Semi Empirical

In this study, a quantitative method for classifying the frost geometry is first proposed to substantiate a numerical model in predicting frost properties like density, thickness, and thermal conductivity. This method can recognize the crystal shape via linear programming of the existing map for frost morphology. By using this method, the frost conditions can be taken into account in a model to obtain the corresponding frost properties like thermal conductivity, frost thickness, and density for specific frost crystal. It is found that the developed model can predict the frost properties more accurately than the existing correlations. Specifically, the proposed model can identify the corresponding frost shape by a dimensionless temperature and the surface temperature. Moreover, by adopting the frost identification into the numerical model, the frost thickness can also be predicted satisfactorily. The proposed calculation method not only shows better predictive ability with thermal conductivities, but also gives good predictions for density and is especially accurate when the frost density is lower than 125 kg/m3. Yet, the predictive ability for frost density is improved by 24% when compared to the most accurate correlation available.

scholarly journals Extrapolability and limitations of a semi-empirical model for the simulation of volumetric expanders

2017 ◽  
Vol 129 ◽  
pp. 315-322 ◽  
Author(s):  
Olivier Dumont ◽  
Rémi Dickes ◽  
Vincent Lemort
Keyword(s):  
Empirical Model ◽  
Semi Empirical

scholarly journals Trees as a solar control measure for southern-oriented street frontages. Analysis of a selected street model for a humid continental climate

2021 ◽  
Author(s):  
Katarzyna Zielonko-Jung ◽  
Justyna Janiak
Keyword(s):  
Numerical Simulation ◽  
Solar Radiation ◽  
Control Measure ◽  
Total Solar Radiation ◽  
Single Row ◽  
Ground Floor ◽  
Radical Reduction ◽  
Solar Control ◽  
Sycamore Maple ◽  
Continental Climate

AbstractThe present study is aimed at the analysis of possibilities for shading southern frontage of street oriented along the E-W axis by the single row of trees, parallel to the southern elevations. The effectiveness of solar control shading was tested depending on the geometric relationships between trees and buildings. Numerical simulation analyses were conducted in Rhinoceros® program for the street located in humid continental climate in city Płock, Poland (52°32′50 “N 19°42’00 “E), for the day of the highest degree of total solar radiation in the year i.e. June 7th, during hours: 8.00a.m - 5.00 p.m. The analysis has proved that a row of 20–25 year old Sycamore Maple ‘Rotterdam’ in the street 30 m wide and 18 m high (H/W = 0.6), can provide solar protection for the southern frontage, especially when trees are located no more than 4 m away. Location of greenery within the range of 4 to 5 m from the buildings leads to a radical reduction in the possibility of shading the wall surfaces (at 5 m to 0%). Over 90% of the shading area of the ground floor façade walls was found when trees were within the distance 2 and 3 m away from the building.

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