Seasonal temperature and stress distributions in concrete gravity dams. Part 2: behaviour

1993 ◽  
Vol 20 (6) ◽  
pp. 1018-1029 ◽  
Author(s):  
P. Léger ◽  
J. Venturelli ◽  
S. S. Bhattacharjee
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Thermal Stresses ◽  
Thermal Response ◽  
Structural Safety ◽  
Seasonal Temperature ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Frost Penetration ◽  
Parametric Analyses

The thermal response of a typical dam–foundation–reservoir system, using the methodology described in part 1, is presented. Extensive parametric analyses are performed to determine the relative influence, on the thermal and stress–strain responses of the system, due to (i) the geometrical, thermal, and mechanical properties of the dam, (ii) the reservoir, foundation, and air temperature distributions, and (iii) the heat supply from solar radiation. Temperature states to define critical stress conditions for structural safety analyses are determined. Significant thermal stresses occur in the vicinity of the exposed surface of the dam, with a typical depth of frost penetration of about 6 m. The parameters that affect the surface stresses most are the air temperature distribution and the height of the dam, while for frost penetration they are the solar radiation, convection coefficient, and conduction coefficient. Key words: gravity dams, thermal analysis, finite element method.

Seasonal temperature and stress distributions in concrete gravity dams. Part 1: modelling

1993 ◽  
Vol 20 (6) ◽  
pp. 999-1017 ◽  
Author(s):  
P. Léger ◽  
J. Venturelli ◽  
S. S. Bhattacharjee
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Thermal Response ◽  
Companion Paper ◽  
Seasonal Temperature ◽  
Gravity Dams ◽  
Dam Foundation ◽  
Temperature Variations ◽  
Concrete Gravity Dams ◽  
Northern Regions

Seasonal thermal stresses have been found to contribute significantly to the long-term degradation of strength and stiffness of concrete dams located in northern regions. Temperature variations and the associated thermal stress and strain must be evaluated to define the initial loading conditions for safety analyses and develop defensive measures to ensure the durability of the exposed surfaces. This paper presents a finite element modelling procedure to determine the thermal response of concrete gravity dams. Heat transfer and structural analysis models of a typical dam–foundation–reservoir system are developed. The reservoir, foundation, and air temperature variations, as well as solar radiation, are evaluated from data collected from different sources. The rate of convergence of the numerical solution is examined, and a methodology to identify the critical temperature states and to compute the related stresses is presented. The results of extensive parametric analyses describing the thermal behaviour of concrete gravity dams located in northern regions are presented in a companion paper. Key words: gravity dams, thermal analysis, finite element method.

Temperature Annual Cycle Variation and Response to Solar Radiation during 1960 to 2016 in China

2020 ◽  
Author(s):  
Runze Zhao ◽  
Kaicun Wang ◽  
Guocan Wu ◽  
Chunlue Zhou
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Annual Cycle ◽  
Surface Air Temperature ◽  
Seasonal Temperature ◽  
Surface Solar Radiation ◽  
Seasonal Temperature Variation ◽  
Phase Amplitude ◽  
Original Time ◽  
Effect Of Surface

<p>The change of its annual cycle is extremely important due to global warming. A widely used method to analyze the changes of temperature annual cycle is based on the decomposition to phase, amplitude and baseline terms. Solar radiation as the leading energy source of temperature changes can directly influence temperature annual cycle. In this study, we investigate the phase, amplitude and baseline of temperature and solar radiation annual cycle after Fourier transform during 1960-2016 in China. The results show that annual cycle of maximum, minimum and mean surface air temperature are advancing in time (-0.08, -0.27 and -0.33 days per ten years), decreasing in range (-0.07, -0.25 and -0.18 degrees per ten years) and rising in baseline (0.20, 0.34 and 0.25 degrees per ten years). To further quantify the effect of surface solar radiation to temperature, we remove the effect from its original time series of maximum and mean temperature, based on a linear regression. The compare of raw and adjusted temperature shows that surface solar radiation advancing the time by 0.19 and 0.19 days per ten years, reduces the range by 0.14 and 0.13 degrees per ten years, and reduces the baseline by 0.08 and 0.04 degrees per ten years, for surface maximum and mean daily air temperature. The result can explain parts of seasonal temperature variation. Effect of surface solar radiation is most obvious Yunnan-Guizhou Plateau for maximum phase. The low phase value in this area is corrected and well-match with other same latitude area after adjusted.</p>

Climatic controls on active layer dynamics: Amsler Island, Antarctica

2016 ◽  
Vol 29 (2) ◽  
pp. 173-182 ◽  
Author(s):  
Kelly R. Wilhelm ◽  
James G. Bockheim
Keyword(s):  
Solar Radiation ◽  
Snow Cover ◽  
Active Layer ◽  
Air Temperature ◽  
Ground Surface ◽  
Ground Temperature ◽  
Seasonal Temperature ◽  
Atmospheric Conditions ◽  
Temperature Variations ◽  
Ground Temperatures

AbstractVariations in atmospheric conditions can be important factors influencing temperature dynamics within the active layer of a soil. Solar radiation and air temperature can directly alter ground surface temperatures, while variations in wind and precipitation can control how quickly heat is carried through soil pores. The presence of seasonal snow cover can also create a thermal barrier between the atmosphere and ground surface. This study examines the relation between atmospheric conditions and ground temperature variations on a deglaciated island along the Western Antarctic Peninsula. Ground temperatures were most significantly influenced by incoming solar radiation, followed by air temperature variations. When winter months were included in the comparison, the influence of air temperature increased while solar radiation became less influential, indicating that snow cover reflected solar radiation inputs, but was not thick enough to insulate the ground. When ground temperatures were compared to atmospheric conditions of preceding weeks, seasonal temperature peaks 1.6 m below ground were best related to seasonal air temperature peaks from the previous two weeks. The same ground temperature peaks were best related to seasonal solar radiation peaks of seven weeks prior. This difference was a result of temperature lags within the atmosphere.

scholarly journals Detrended Multiple Cross-Correlation Coefficient applied to solar radiation, air temperature and relative humidity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea de Almeida Brito ◽  
Heráclio Alves de Araújo ◽  
Gilney Figueira Zebende
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Solar Energy ◽  
Correlation Coefficient ◽  
Air Temperature ◽  
Cross Correlation ◽  
Global Solar Radiation ◽  
Meteorological Variables ◽  
Hourly Data ◽  
Cross Correlations

AbstractDue to the importance of generating energy sustainably, with the Sun being a large solar power plant for the Earth, we study the cross-correlations between the main meteorological variables (global solar radiation, air temperature, and relative air humidity) from a global cross-correlation perspective to efficiently capture solar energy. This is done initially between pairs of these variables, with the Detrended Cross-Correlation Coefficient, ρDCCA, and subsequently with the recently developed Multiple Detrended Cross-Correlation Coefficient, $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2. We use the hourly data from three meteorological stations of the Brazilian Institute of Meteorology located in the state of Bahia (Brazil). Initially, with the original data, we set up a color map for each variable to show the time dynamics. After, ρDCCA was calculated, thus obtaining a positive value between the global solar radiation and air temperature, and a negative value between the global solar radiation and air relative humidity, for all time scales. Finally, for the first time, was applied $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}$$DMCx2 to analyze cross-correlations between three meteorological variables at the same time. On taking the global radiation as the dependent variable, and assuming that $${\boldsymbol{DM}}{{\boldsymbol{C}}}_{{\bf{x}}}^{{\bf{2}}}={\bf{1}}$$DMCx2=1 (which varies from 0 to 1) is the ideal value for the capture of solar energy, our analysis finds some patterns (differences) involving these meteorological stations with a high intensity of annual solar radiation.

scholarly journals Solar Radiation, Air Temperature, Relative Humidity, and Dew Point Study: Damak, Jhapa, Nepal

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Arun Kumar Shrestha ◽  
Arati Thapa ◽  
Hima Gautam
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Gaussian Function ◽  
Great Influence ◽  
Dew Point ◽  
Upward Trend ◽  
Summer Maximum ◽  
Online Calculator ◽  
Climatic Phenomenon

Monitoring and prediction of the climatic phenomenon are of keen interest in recent years because it has great influence in the lives of people and their environments. This paper is aimed at reporting the variation of daily and monthly solar radiation, air temperature, relative humidity (RH), and dew point over the year of 2013 based on the data obtained from the weather station situated in Damak, Nepal. The result shows that on a clear day, the variation of solar radiation and RH follows the Gaussian function in which the first one has an upward trend and the second one has a downward trend. However, the change in air temperature satisfies the sine function. The dew point temperature shows somewhat complex behavior. Monthly variation of solar radiation, air temperature, and dew point shows a similar pattern, lower at winter and higher in summer. Maximum solar radiation (331 Wm-2) was observed in May and minimum (170 Wm-2) in December. Air temperature and dew point had the highest value from June to September nearly at 29°C and 25°C, respectively. The lowest value of the relative humidity (55.4%) in April indicates the driest month of the year. Dew point was also calculated from the actual readings of air temperature and relative humidity using the online calculator, and the calculated value showed the exact linear relationship with the observed value. The diurnal and nocturnal temperature of each month showed that temperature difference was relatively lower (less than 10°C) at summer rather than in winter.

scholarly journals Transmission of solar radiation through clouds on melting glaciers: a comparison of parameterizations and their impact on melt modelling

2011 ◽  
Vol 57 (202) ◽  
pp. 367-381 ◽  
Author(s):  
Francesca Pellicciotti ◽  
Thomas Raschle ◽  
Thomas Huerlimann ◽  
Marco Carenzo ◽  
Paolo Burlando
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Radiative Forcing ◽  
Model Performance ◽  
Horizontal Resolution ◽  
Swiss Alps ◽  
Cloud Radiative Forcing ◽  
Correct Definition ◽  
Diurnal Range ◽  
The Impact

AbstractWe explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the Swiss Alps. We also look at the rationale behind some of the most commonly used approaches, and explore the relationship between cloud transmittance and several standard meteorological variables. The 2 m air-temperature diurnal range is the best predictor of variations in cloud transmittance. However, linear and exponential parameterizations can only explain 30–50% of the observed variance in computed cloud transmittance factors. We examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature-index model. The melt model performance decreases when modelled radiation is used, the reduction being due to an underestimation of incoming solar radiation on clear-sky days. The model works well under overcast conditions. We also seek alternatives to the use of in situ ground data. However, outputs from an atmospheric model (2.2 km horizontal resolution) do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations. Conversely, the correct definition of overcast conditions is important.

A reflexion on the environmental effect on the transmission of COVID-19

2021 ◽  
Author(s):  
Victor L Barradas ◽  
Monica Ballinas
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Low Temperatures ◽  
Minimum Distance ◽  
Vapor Pressure Deficit ◽  
Environmental Parameters ◽  
Air Humidity ◽  
Evaporative Demand ◽  
Small Water ◽  
The Hours

<p>This research is a general reflection of the possible transmission not only of COVID-19 but of any influenza disease depending on environmental parameters such as solar radiation, air humidity and air temperature (vapor pressure deficit), evoking the Penman-Monteith model regarding the evaporation of the water that constitutes the small water droplets (aerosols) that carry the virus. In this case the evapotranspiration demand of the atmosphere with which it can be deduced that the spread of the disease will be higher in those places with less evaporative demand, that is, high air humidity and / or low temperatures, and / or low radiation intensities, and vice versa. It can also be deduced that the hours of greatest potential contagion are the night hours, while those with the lowest risk are between 2:00 p.m. and 4:00 p.m. On the other hand, in those rooms with low temperatures the contagion would be more effective. So, considering that the drops produced by a sneeze, by speaking or breathing can go beyond two meters away, it is roughly explained that the use of face masks and keeping a safe minimum distance of two meters can limit transmission of viruses and / or infections. However, this practice is not entirely safe as the environment can play an important role. What is recommended to reduce the spread of these pathogens is to produce high evaporative demands: increasing solar radiation, and increasing air temperature and reducing air humidity, which is practice that can be effective in closed rooms.</p>

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