scholarly journals Intercomparação de sensores de temperatura e umidade relativa para uso em campanha micrometeorológica

2020 ◽  
Vol 42 ◽  
pp. e18
Author(s):  
Lucas Emilio B. Hoeltgebaum ◽  
André Luís Diniz ◽  
Nelson Luís da Costa Dias
Keyword(s):  
Relative Humidity ◽  
Sonic Anemometer ◽  
Vapor Concentration ◽  
Gas Analyzer ◽  
Humidity Standard ◽  
Air Temperatures ◽  
Standard Linear ◽  
Intercomparison Study ◽  
Linear Correlations ◽  
Good Agreement

In this work we present results from an intercomparison study between two CS500 temperature-relative humidity sensors and a brand new sonic anemometer/gas analyzer (Campbell Scientific Instruments – CSI IRGASON). The objective of the intercomparison was an upcoming micrometeorological experiment. For the intercomparison, all sensors were positioned at the same height over the water surface, at the Rio Verde reservoir, in the vicinity of Curitiba, PR, Brazil. The compared variables were air temperature and relative humidity. The CS500 air temperatures were compared to those from a CSI 107 temperature sensor operates with the IRGASON; for the relative humidity comparisons, water vapor concentration measured by the IRGASON was converted to an equivalent relative humidity. Standard linear correlations were calculated. The CS500s displayed good agreement with the IRGASON-derived values.

scholarly journals Quantifying the Independent Influences of Land Cover and Humidity on Microscale Urban Air Temperature Variation in Hot Summer: Methods of Path Analysis and Genetic SVR

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1377
Author(s):  
Weifang Shi ◽  
Nan Wang ◽  
Aixuan Xin ◽  
Linglan Liu ◽  
Jiaqi Hou ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Land Cover ◽  
Path Analysis ◽  
Temperature Variation ◽  
Direct Effect ◽  
Air Temperature ◽  
Urban Areas ◽  
Support Vector ◽  
Urban Air ◽  
Air Temperatures

Mitigating high air temperatures and heat waves is vital for decreasing air pollution and protecting public health. To improve understanding of microscale urban air temperature variation, this paper performed measurements of air temperature and relative humidity in a field of Wuhan City in the afternoon of hot summer days, and used path analysis and genetic support vector regression (SVR) to quantify the independent influences of land cover and humidity on air temperature variation. The path analysis shows that most effect of the land cover is mediated through relative humidity difference, more than four times as much as the direct effect, and that the direct effect of relative humidity difference is nearly six times that of land cover, even larger than the total effect of the land cover. The SVR simulation illustrates that land cover and relative humidity independently contribute 16.3% and 83.7%, on average, to the rise of the air temperature over the land without vegetation in the study site. An alternative strategy of increasing the humidity artificially is proposed to reduce high air temperatures in urban areas. The study would provide scientific support for the regulation of the microclimate and the mitigation of the high air temperature in urban areas.

On the Use of Monolayers to Reduce Evaporation From Stationary Water Pools

1993 ◽  
Vol 115 (1) ◽  
pp. 209-214 ◽  
Author(s):  
T. D. Tang ◽  
M. T. Pauken ◽  
S. M. Jeter ◽  
S. I. Abdel-Khalik
Keyword(s):  
Experimental Investigation ◽  
Relative Humidity ◽  
Water Surface ◽  
Surface Film ◽  
Free Water ◽  
Vapor Concentration ◽  
Controlled Environment ◽  
Stearyl Alcohol ◽  
Water Pool ◽  
Evaporation Suppression

An experimental investigation has been conducted to quantify the extent by which monolayers of fatty alcohols can reduce evaporation from a deep stationary water pool within a controlled environment. Octadecanol (stearyl alcohol), C17H35–CH2–OH, was chosen as the surface film and ethanol was selected to be the spreading agent. Evaporation suppression of 60 percent was achieved at a water temperature of 25°C with an air temperature of 20°C and a relative humidity of 70 percent. The experimental techniques and data have been validated by comparing the measured evaporation rates for film-free water with earlier data published by other investigators. Data for the evaporation rates of water covered by octadecanol films were correlated as a function of vapor concentration differences between the water surface and air.

scholarly journals Using Waveguides to Model the Dynamic Stiffness of Pre-Compressed Natural Rubber Vibration Isolators

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1703
Author(s):  
Michael Coja ◽  
Leif Kari
Keyword(s):  
Natural Rubber ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Complex Problem ◽  
Wide Frequency Range ◽  
Vibration Isolators ◽  
Standard Linear Solid ◽  
Standard Linear ◽  
Frequency Magnitude ◽  
Good Agreement

A waveguide model for a pre-compressed cylindrical natural rubber vibration isolator is developed within a wide frequency range—20 to 2000 Hz—and for a wide pre-compression domain—from vanishing to the maximum in service, that is 20%. The problems of simultaneously modeling the pre-compression and frequency dependence are solved by applying a transformation of the pre-compressed isolator into a globally equivalent linearized, homogeneous, and isotropic form, thereby reducing the original, mathematically arduous, and complex problem into a vastly simpler assignment while using a straightforward waveguide approach to satisfy the boundary conditions by mode-matching. A fractional standard linear solid is applied as the visco-elastic natural rubber model while using a Mittag–Leffler function as the stress relaxation function. The dynamic stiffness is found to depend strongly on the frequency and pre-compression. The former is resulting in resonance phenomena such as peaks and troughs, while the latter exhibits a low-frequency magnitude stiffness increase in addition to peak and trough shifts with increased pre-compressions. Good agreement with nonlinear finite element results is obtained for the considered frequency and pre-compression range in contrast to the results of standard waveguide approaches.

scholarly journals Wind Estimation in the Lower Atmosphere Using Multirotor Aircraft

2017 ◽  
Vol 34 (5) ◽  
pp. 1183-1191 ◽  
Author(s):  
Ross T. Palomaki ◽  
Nathan T. Rose ◽  
Michael van den Bossche ◽  
Thomas J. Sherman ◽  
Stephan F. J. De Wekker
Keyword(s):  
Wind Speed ◽  
Sonic Anemometer ◽  
Unmanned Aircraft ◽  
Lower Atmosphere ◽  
Promising Alternative ◽  
Atmospheric Structure ◽  
Structure And Dynamics ◽  
Sonic Anemometers ◽  
Vertical Profiling ◽  
Good Agreement

AbstractUnmanned aerial vehicles are increasingly used to study atmospheric structure and dynamics. While much emphasis has been on the development of fixed-wing unmanned aircraft for atmospheric investigations, the use of multirotor aircraft is relatively unexplored, especially for capturing atmospheric winds. The purpose of this article is to demonstrate the efficacy of estimating wind speed and direction with 1) a direct approach using a sonic anemometer mounted on top of a hexacopter and 2) an indirect approach using attitude data from a quadcopter. The data are collected by the multirotor aircraft hovering 10 m above ground adjacent to one or more sonic anemometers. Wind speed and direction show good agreement with sonic anemometer measurements in the initial experiments. Typical errors in wind speed and direction are smaller than 0.5 and 30°, respectively. Multirotor aircraft provide a promising alternative to traditional platforms for vertical profiling in the atmospheric boundary layer, especially in conditions where a tethered balloon system is typically deployed.

scholarly journals Drying characteristics and kinetics of fluidized bed dried potato

2008 ◽  
Vol 19 (2) ◽  
pp. 127 ◽  
Author(s):  
S.B. BAKAL ◽  
K.H. GEDAM ◽  
G.P. SHARMA
Keyword(s):  
Activation Energy ◽  
Developed Countries ◽  
Moisture Diffusivity ◽  
Drying Characteristics ◽  
Effective Moisture ◽  
Air Temperatures ◽  
Processed Products ◽  
Drying Conditions ◽  
Kinetics Of ◽  
Good Agreement

In developed countries, more than 50% potatoes are consumed as processed products. As drying is the vital phenomenon in processing, it is necessary to investigate the drying characteristics and its kinetics. In this experimental study, drying kinetics of Potato in two different shape of cuboidal & cylindrical with three aspect ratio was investigated as a function of drying conditions. Experiments were conducted using air temperatures of 50, 60 and 70 ºC, at velocity of 7 ms-1. The experimental moisture data were fitted to Page and simple models available in the literature, and a good agreement was observed. The Page model gave better fit than simple model. In the ranges covered, the values of the effective moisture diffusivity, Deff were obtained between 2.278 × 10-9 to 3.314 × 10-8 m2s-1 from the Fick's diffusion model. Using Deff, the value of activation energy (Ea) was determined assuming the Arrhenius-type temperature relationship.

Modelling the Natural Evaporation of the Concentrated Seawater after Desalinized

2015 ◽  
Vol 713-715 ◽  
pp. 2989-2992
Author(s):  
Xue Kui Wang ◽  
Ying Zhou ◽  
Ling Li ◽  
Tian Cheng Gao ◽  
Na Tang
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Artificial Neural Network ◽  
Relative Humidity ◽  
Evaporation Rate ◽  
Evaporation Model ◽  
Irradiation Intensity ◽  
Artificial Neural ◽  
Good Agreement

The influence of natural evaporation factors (the irradiation intensity, speed of the wind, temperature of the brine, temperature and relative humidity of the air) on the desalinated seawater evaporation rate was measured experimentally. A natural evaporation model was built by correlating the experimental data using the artificial neural network. This model was well correlated with the influence of natural evaporation factors, and it showed a good agreement of the results and evaporation theory.

Characterization of KIM LIPI’s Relative Humidity Standard

MAPAN ◽  
2013 ◽  
Vol 29 (1) ◽  
pp. 51-55 ◽  
Author(s):  
Arfan Sindhu Tistomo ◽  
Aditya Achmadi ◽  
Iip Ahmad Rifai
Keyword(s):  
Relative Humidity ◽  
Humidity Standard

Applying the Passivhaus standard to a terraced house in a hot and humid tropical climate – Evaluation of comfort and energy performance

2020 ◽  
Vol 41 (3) ◽  
pp. 247-260
Author(s):  
Roy Candra Sigalingging ◽  
David Chow ◽  
Steve Sharples
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Best Practice ◽  
Natural Ventilation ◽  
Tropical Climate ◽  
Energy Performance ◽  
Tropical Region ◽  
Humid Tropical Climate ◽  
Air Temperatures

In a hot and humid tropical climate, natural ventilation brings high levels of moisture into dwellings that, together with occupant activity, can result in very elevated internal relative humidity levels. Coupling these high relative humidities with high internal air temperatures creates occupant thermal discomfort, which is typically ameliorated in the tropics using energy-intensive air conditioning systems. This paper has investigated the potential benefits for thermal comfort and energy usage of applying the German Passivhaus standard to tropical dwellings. By creating a super insulated and air-tight envelope, the Passivhaus standard reduces fabric heat transfer, controls air infiltration and provides low-energy comfort. Applying this approach to a tropical terraced house might be effective but could, potentially, have an adverse impact on mechanical cooling demand. This study took an actual terraced property in Jakarta, Indonesia and thermally modelled its performance as insulation and airtightness levels were incrementally improved up to the Passivhaus standard. Field measurements in the dwelling of air temperature and relative humidity were used to validate the thermal model of the existing house. The validated model then tested the feasibility of meeting the Passivhaus energy standard for cooling in the modified tropical house. Simulation allowed the effects of air conditioning (AC) and dehumidifiers on thermal comfort and cooling loads to be investigated. The research develop the Passivhaus building model that had the floor insulation removed to let the ground floor act as a thermal sink and potentially provide radiant cooling. Analysis revealed that the building’s predicted air temperatures were affected in a beneficial way by having the Passivhaus without floor insulation. Practical application: Cooling in hot and humid tropical region is an energy-intensive approach. Design approaches that can bring comfort and save energy for the occupant are essential. The success of Passivhaus standard in mild climate might be transferable to bring comfort in tropical housing. Best practice can be developed by analysing the Passivhaus building performance in hot and humid tropical region.

scholarly journals Numerical and experimental investigation on the thermal behaviour of the building integrating occupant thermal comfort

2020 ◽  
Vol 307 ◽  
pp. 01025 ◽  
Author(s):  
Abed Al Waheed Hawila ◽  
Abdelatif Merabtine ◽  
Nadège Troussier
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Thermal Behaviour ◽  
Room Temperature ◽  
Maximum Error ◽  
Measured Data ◽  
Influential Factor ◽  
Simulation Tools ◽  
Good Agreement

Simulation tools are widely used to model buildings in order to predict their indoor air quality and energy consumption. The prediction capability of the model is an influential factor in determining the ability of the building to be energy efficient and thermally comfortable. Thus, the validation of the developed models is crucial. In this context, this paper presents a numerical model developed using an object-oriented modelling tool based on the Modelica approach and a case study validation of this model. Then the thermal behaviour of the building and the occupants’ thermal comfort in the considered case study are investigated. The objective is to validate the developed model firstly by comparing predicted results with measured data regarding room temperature and relative humidity, and secondly by comparing the calculated thermal comfort indices (PMV and PPD) based on predicted results and measured data. The results show good agreement between simulations and experiments, with a maximum error in room temperature and relative humidity of 1.7 °C and 4.5%, respectively, and only 1% and 1.5% difference between averaged values of PMV and PPD, respectively.

The Capillary Force Between an AFM Tip and a Surface at Different Humidity

2008 ◽  
Author(s):  
Sheng Chau Chen ◽  
Jen Fin Lin
Keyword(s):  
Relative Humidity ◽  
Capillary Force ◽  
Present Model ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Hydrophilic Surface ◽  
Solid Bodies ◽  
Force Equilibrium ◽  
Good Agreement

In the present study, the meniscus profiles of water bridges formed at different relative humidity are determined using the geometric relationships including the Kelvin equation and the force equilibrium formula established for the meniscus. The pull-off forces predicted by the present model show good agreement with the experimental results reported in the literatures. When the contact angles at two solid bodies are equal, the pull-off force is slightly elevated by an increase of the relative humidity of air, and is significantly elevated by an increase of the asperity radius. Furthermore, two hydrophobic surfaces with equally large contact angles lower the pull-off force. If a difference exists between the contact angles of two solid surfaces, the asperity with a hydrophilic surface incorporating with a smooth flat plate with a hydrophobic surface reduces the pull-off force.

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